WO2005119262A2 - Methods, compositions and compound assays for inhibiting amyloid-beta protein production - Google Patents

Abstract

A method for identifying compounds that inhibit amyloid-beta precursor protein processing in cells, comprising contacting a test compound with a HIT polypeptide, or fragment thereof, and measuring a compound-HIT property related to the production of amyloid-beta peptide. Cellular assays of the method measure indicators including cleaved protease substrates, phosphorylated kinase substrate, second messenger levels and/or amyloid beta peptide levels. Therapeutic methods, and pharmaceutical compositions including effective amyloid-beta precursor processing-inhibiting amounts of HIT expression inhibitors, are useful for treating conditions involving cognitive impairment such as Alzheimer's disease.

Description

METHODS, COMPOSITIONS AND COMPOUND ASSAYS FOR INHIBITING AMYLOID-BETA PROTEIN PRODUCTION

Field of the Invention This invention relates to the field of mammalian neuronal cell disorders, and in particular, to methods for identifying effective compounds, and therapies and compositions using such compounds, useful for the prevention and treatment of diseases associated with progressive loss of intellectual capacities in humans. The neurological disorder that is most widely known for its progressive loss of intellectual capacities is Alzheimer's disease (AD). Worldwide, about 20 million people suffer from Alzheimer's disease. AD is clinically characterized by the initial loss of memory, followed by disorientation, impairment of judgment and reasoning, which is commonly referred to as cognitive impairment, and ultimately by full dementia. AD patients finally lapse into a severely debilitated, immobile state between four and twelve years after onset of the disease. The key pathological evidence for AD is the presence of extracellular amyloid plaques and mtracellular tau tangles in the brain, which are associated with neuronal degeneration (Ritchie and Lovestone (2002)). The extracellular amyloid plaques are believed to result from an increase in the insoluble amyloid beta peptide 1-42 produced by the metabolism of amyloid-beta precursor protein (APP). Following secretion, these amyloid beta 1-42 peptides form amyloid fibrils more readily than the amyloid beta 1-40 peptides, which are predominantly produced in healthy people. It appears that the amyloid beta peptide is on top of the neurotoxic cascade: experiments show that amyloid beta fibrils, when injected into the brains of P301L tau transgenic mice, enhance the formation of neurofibrillary tangles (Gotz et al. (2001)). In fact, a variety of amyloid beta peptides have been identified as amyloid beta peptides 1-42, 1-40, 1-39, 1-38, 1-37, which can be found in plaques and are often seen in cerebral spinal fluid. The amyloid beta peptides are generated (or processed) from the membrane anchored

APP, after cleavage by beta secretase and gamma secretase at position 1 and 40 or 42, respectively (Figure 1 A)(Annaert and De Strooper (2002)). In addition, high activity of beta secretase results in a shift of the cleavage at position 1 to position 11. Cleavage of amyloid- beta precursor protein by alpha secretase activity at position 17 and gamma secretase activity at 40 or 42 generates the non-pathological p3 peptide. Beta secretase is identified as the membrane anchored aspartyl protease BACE, while gamma secretase is a protein complex comprising presenilin 1 (PSI) or presenilin 2 (PS2), nicastrin, Anterior Pharynx Defective 1 (APHl) and Presenilin Enhancer 2 (PEN2). Of these proteins, the presenilins are widely thought to constitute the catalytic activity of the gamma secretase, while the other components play a role in the maturation and localization of the complex. The identity of the alpha secretase is still illustrious, although some results point towards the proteins ADAM 10 and TACE, which could have redundant functions. A small fraction of AD cases (mostly early onset AD) are caused by autosomal dominant mutations in the genes encoding presenilin 1 and 2 (PSI; PS2) and the amyloid- beta precursor protein (APP), and it has been shown that mutations in APP, PSI and PS2 alter the metabolism of amyloid-beta precursor protein leading to such increased levels of amyloid beta 1-42 produced in the brain. Although no mutations in PSI, PS2 and amyloid- beta precursor protein have been identified in late onset AD patients, the pathological characteristics are highly similar to the early onset AD patients. These increased levels of amyloid beta peptide could originate progressively with age from disturbed amyloid-beta precursor protein processing (e.g. high cholesterol levels enhance amyloid beta peptide production) or from decreased amyloid beta peptide catabolism. Therefore, it is generally accepted that AD in late onset AD patients is also caused by aberrant increased amyloid peptide levels in the brains. The level of these amyloid beta peptides, and more particularly amyloid-beta peptide 1-42, is increased in Alzheimer patients compared to the levels of these peptides in healthy persons. Thus, reducing the levels of these amyloid beta peptides is likely to be beneficial for patients with cognitive impairment. Reported Developments The major current AD therapies are limited to delaying progressive memory loss by inhibiting the acetylcholinesterase enzyme, which increases acetylcholine neurotransmitter levels, which fall because the cholinergic neurons are the first neurons to degenerate during AD. This therapy does not halt the progression of the disease. Therapies aimed at decreasing the levels of amyloid beta peptides in the brain, are increasingly being investigated and focus on the perturbed amyloid-beta precursor protein processing involving the beta- or gamma secretase enzymes. The present invention is based on the discovery that certain known polypeptides are factors in the up-regulation and/or induction of amyloid beta precursor processing in neuronal cells, and that the inhibition of the function of such polypeptides are effective in reducing levels of amyloid beta peptides. Summary of the Invention The present invention relates to the relationship between the function of selected proteins ("HITS") and amyloid-beta precursor protein processing in mammalian cells. One aspect of the present invention is a method for identifying a compound that inhibits the processing of amyloid-beta precursor protein in a mammalian cell, comprising (a) contacting a compound with a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732, 801-937; and (b) measuring a compound-polypeptide property related to the production of amyloid-beta peptide. Aspects of the present method include the in vitro assay of compounds using polypeptide of a HIT, and cellular assays wherein HIT inhibition is followed by observing indicators of efficacy, including cleaved protease substrate levels, phosphorylated kinase substrates, second messenger levels and/or amyloid beta peptide levels. Another aspect of the invention is a method of treatment or prevention of a condition involving cognitive impairment, or a susceptibility to the condition, in a subject suffering or susceptible thereto, by administering a pharmaceutical composition comprising an effective amyloid-beta precursor processing-inhibiting amount of a HIT inhibitor. A further aspect of the present invention is a pharmaceutical composition for use in said method wherein said inhibitor comprises a polynucleotide selected from the group of an antisense polynucleotide, a ribozyme, and a small interfering RNA (siRNA), wherein said agent comprises a nucleic acid sequence complementary to, or engineered from, a naturally occurring polynucleotide sequence encoding a polypeptide, comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732, or a fragment thereof , preferably comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 801-937. Another further aspect of the present invention is a pharmaceutical composition comprising a therapeutically effective amyloid-beta precursor processing-inhibiting amount of a HIT inhibitor or its pharmaceutically acceptable salt, hydrate, solvate, or prodrug thereof in admixture with a pharmaceutically acceptable carrier. The present polynucleotides and HIT inhibitor compounds are also useful for the manufacturing of a medicament for the treatment of Alzheimer's disease. Brief Description of the Drawings Figure 1: APP processing: The membrane anchored amyloid precursor protein (APP) is processed by two pathways: the amyloidogenic and non amyloidogenic pathway. In the latter pathway, APP is cleaved first by alpha secretase and then by gamma secretase, yielding the p3 peptides (17-40 or 17-42). The amyloidogenic pathway generates the pathogenic amyloid beta peptides (A beta) after cleavage by beta- and gamma-secretase respectively. The numbers depicted are the positions of the amino acids comprising the A beta sequences.

Figure 2: Evaluation of the APP processing assay: Adenoviruses harboring the APPsw cDNA, BACE1 KD, ALPL KD and RunX2 KD sequences are infected in SH- SY5Y at MOI 2000 and 500. Viruses are washed away and amyloid beta 1-42 levels are determined. Data are represented as pM of amyloid beta 1 -42.

Figure 3: Evaluation of the APP processing assay: Control adenoviruses harboring knock down sequences for BACE1, PSEN1, APH1B, GL2 and ALPL and eGFP are infected in SH-SY5Y. Viruses are washed away and amyloid beta 1-42 levels are determined using the amyloid beta 1-42 ELISA. Amyloid beta 1-42 levels are represented as rlu values. The cut off value is shown as a line.

Figure 4: Adenoviruses expressing siRNA coding for the GL2 KD, eGFP KD, BACE1 KD, EPHA7 KD, DAPK2 KD, DKFZp761P1010 KD and RunX2 KD sequences are transfected in HEK 293APPwt Cells at lOOnM. Viruses are washed away and amyloid beta 1-42 levels are determined by ELISA. Data are represented as pM of amyloid beta 1-42.

Figure 5: Adenoviruses expressing siRNA coding for the GL2 KD, eGFP KD, BACE1 KD and PEK4CA KD sequences are transfected in HEK 293APPwt Cells at lOOnM. Viruses are washed away and amyloid beta 1-42 levels are determined by ELISA. Data are represented as pM of amyloid beta 1-42. Detailed Description The following terms are intended to have the meanings presented therewith below and are useful in understanding the description of and intended scope of the present invention.

Definitions: The term "amyloid beta peptide" means amyloid beta peptides processed from the amyloid beta precursor protein (APP). The most common peptides include amyloid beta peptides 1-40, 1-42, 11-40 and 11-42. Other less prevalent amyloid beta peptide species are included in the subgenus of amyloid beta peptides described as x-42, whereby x ranges from 2-10 and 12-17, and 1-y whereby y ranges from 24-39 and 41. For descriptive and technical purposes hereinbelow, "x" has a value of 2-17, and "y" has a value of 24 to 41. The term "carrier" means a non-toxic material used in the formulation of pharmaceutical compositions to provide a medium, bulk and/or useable form to a pharmaceutical composition. A carrier may comprise one or more of such materials such as an excipient, stabilizer, or an aqueous pH buffered solution. Examples of physiologically acceptable carriers include aqueous or solid buffer ingredients including phosphate, citrate, and other organic acids; antioxidants including ascorbic acid; low molecular weight (less than about 10 residues) polypeptide; proteins, such as serum bumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counter ions such as sodium; and or nonionic surfactants such as TWEEN™, polyethylene glycol (PEG), and PLURONICS™. The term "compound" is used herein in the context of a "test compound" or a "drug candidate compound" described in connection with the assays of the present invention. As such, these compounds comprise organic or inorganic compounds, derived synthetically or from natural sources. The compounds include inorganic or organic compounds such as polynucleotides, lipids or hormone analogs that are characterized by relatively low molecular weights. Other biopolymeric organic test compounds include peptides comprising from about 2 to about 40 amino acids and larger polypeptides comprising from about 40 to about 500 amino acids, such as antibodies or antibody conjugates. The term "contact" or "contacting" means bringing at least two moieties together, whether in an in vitro system or an in vivo system. The term "condition" or "disease" means the overt presentation of symptoms (i.e., illness) or the manifestation of abnormal clinical indicators (e.g., biochemical indicators), resulting from defects in one amyloid beta protein precursor processing. Alternatively, the term "disease" refers to a genetic or environmental risk of or propensity for developing such symptoms or abnormal clinical indicators. The term "endogenous" shall mean a material that a mammal naturally produces.

Endogenous in reference to the term "protease", "kinase", or G-Protein Coupled Receptor ("GPCR") shall mean that which is naturally produced by a mammal (for example, and not limitation, a human). In contrast, the term non-endogenous in this context shall mean that which is not naturally produced by a mammal (for example, and not limitation, a human).

Both terms can be utilized to describe both "in vivo" and "in vitro" systems. For example, and not a limitation, in a screening approach, the endogenous or non-endogenous HIT may be in reference to an in vitro screening system. As a further example and not limitation, where the genome of a mammal has been manipulated to include a non-endogenous HIT, screening of a candidate compound by means of an in vivo system is viable. The term "expression" comprises both endogenous expression and overexpression by transduction. The term "expressible nucleic acid" means a nucleic acid coding for a proteinaceous molecule, an RNA molecule, or a DNA molecule. The term "hybridization" means any process by which a strand of nucleic acid binds with a complementary strand through base pairing. The term "hybridization complex" refers to a complex formed between two nucleic acid sequences by virtue of the formation of hydrogen bonds between complementary bases. A hybridization complex may be formed in solution (e.g., Cot or Rot analysis) or formed between one nucleic acid sequence present in solution and another nucleic acid sequence immobiHzed on a solid support (e.g., paper, membranes, filters, chips, pins or glass slides, or any other appropriate substrate to which cells or their nucleic acids have been fixed). The term "stringent conditions" refers to conditions that permit hybridization between polynucleotides and the claimed polynucleotides. Stringent conditions can be defined by salt concentration, the concentration of organic solvent, e.g., formamide, temperature, and other conditions well known in the art. In particular, reducing the concentration of salt, increasing the concentration of formamide, or raising the hybridization temperature can increase stringency. The term "inhibit" or "inhibiting", in relationship to the term "response" means that a response is decreased or prevented in the presence of a compound as opposed to in the absence of the compound. The term "HIT" or "HITS" means the proteins identified in accordance with the present amyloid peptide assay to be involved in the induction of amyloid beta peptide levels. •*> The preferred HITS are identified in Table 1. The more preferred HITS are the kinases, proteases and G-Protein Coupled Receptors (GPCR's) identified in Table 1. The term "ligand" means an endogenous, naturally occurring molecule specific for an endogenous, naturally occurring receptor. The term "pharmaceutically acceptable prodrugs" as used herein means the prodrugs of the compounds useful in the present invention, which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of patients with undue toxicity, irritation, allergic response commensurate with a reasonable benefit/risk ratio, and effective for their intended use of the compounds of the invention. The term "prodrug" means a compound that is transformed in vivo to yield an effective compound useful in the present invention or a pharmaceutically acceptable salt, hydrate or solvate thereof. The transformation may occur by various mechanisms, such as through hydrolysis in blood. The compounds bearing metabolically cleavable groups have the advantage that they may exhibit improved bioavailability as a result of enhanced solubility and or rate of absorption conferred upon the parent compound by virtue of the presence of the metabolically cleavable group, thus, such compounds act as pro-drugs. A thorough discussion is provided in Design of Prodrugs, H. Bundgaard, ed., Elsevier (1985); Methods in Enzymology; K. Widder et al, Ed., Academic Press, 42, 309-396 (1985); A Textbook of Drug Design and Development, Krogsgaard-Larsen and H. Bandaged, ed., Chapter 5; "Design and Applications of Prodrugs" 113-191 (1991); Advanced Drag Delivery Reviews, H. Bundgard, 8 , 1-38, (1992); J. Pharm. Sci., 77,285 (1988); Chem. Pharm. Bull., N. Nakeya et al, 32, 692 (1984); Pro-drugs as Novel Delivery Systems, T. Higuchi and V. Stella, 14 A.C.S. Symposium Series, and Bioreversible Carriers in Drag Design, E.B. Roche, ed., American Pharmaceutical Association and Pergamon Press, 1987, which are incorporated herein by reference. An example of the prodrugs is an ester prodrug. "Ester prodrug" means a compound that is convertible in vivo by metabolic means (e.g., by hydrolysis) to an inhibitor compound according to the present invention. For example an ester prodrug of a compound containing a carboxy group may be convertible by hydrolysis in vivo to the corresponding carboxy group. The term "pharmaceutically acceptable salts" refers to the non-toxic, inorganic and organic acid addition salts, and base addition salts, of compounds of the present invention. These salts can be prepared in situ during the final isolation and purification of compounds useful in the present invention. . The term "polynucleotide" means a polynucleic acid, in single or double stranded form, and in the sense or antisense orientation, complementary polynucleic acids that hybridize to a particular polynucleic acid under stringent conditions, and polynucleotides that are homologous in at least about 60 percent of its base pairs, and more preferably 70 percent of its base pairs are in common, most preferably 90 per cent, and in a special embodiment 100 percent of its base pairs. The polynucleotides include polyribonucleic acids, polydeoxyribonucleic acids, and synthetic analogues thereof. The polynucleotides are described by sequences that vary in length, that range from about 10 to about 5000 bases, preferably about 100 to about 4000 bases, more preferably about 250 to about 2500 bases. A preferred polynucleotide embodiment comprises from about 10 to about 30 bases in length. A special embodiment of polynucleotide is the polyribonucleotide of from about 10 to about 22 nucleotides, more commonly described as small interfering RNAs (siRNAs). Another special embodiment are nucleic acids with modified backbones such as peptide nucleic acid (PNA), polysiloxane, and 2'-O-(2-methoxy)ethylphosphorothioate, or including non-naturally occurring nucleic acid residues, or one or more nucleic acid substituents, such as methyl-, thio-, sulphate, benzoyl-, phenyl-, amino-, propyl-, chloro-, and methanocarbanucleosides, or a reporter molecule to facilitate its detection. The term "polypeptide" relates to proteins (such as HITS), proteinaceous molecules, fractions of proteins peptides and oligopeptides. The term "solvate" means a physical association of a compound useful in this invention with one or more solvent molecules. This physical association includes hydrogen bonding. In certain instances the solvate will be capable of isolation, for example when one or more solvent molecules are incorporated in the crystal lattice of the crystalline solid. "Solvate" encompasses both solution-phase and isolable solvates. Representative solvates include hydrates, ethanolates and methanolates. The term "subject" includes humans and other mammals. The term "effective amount" or "therapeutically effective amount" means that amount of a compound or agent that will elicit the biological or medical response of a subject that is being sought by a medical doctor or other clinician. In particular, with regard to treating an neuronal disorder, the term "effective amount" is intended to mean that effective amyloid- beta precursor processing inhibiting amount of an compound or agent that will bring about a biologically meaningful decrease in the levels of amyloid beta peptide in the subject's brain tissue. The term "treating" means an intervention performed with the intention of preventing the development or altering the pathology of, and thereby alleviating a disorder, disease or condition, mcluding one or more symptoms of such disorder or condition. Accordingly, "treating" refers to both therapeutic treatment and prophylactic or preventative measures. Those in need of treating include those already with the disorder as well as those in which the disorder is to be prevented. The related term "treatment," as used herein, refers to the act of treating a disorder, symptom, disease or condition, as the term "treating" is defined above.

Applicants' Invention Based on HIT Relationship to Amyloid Beta Peptides As noted above, the present invention is based on the present inventors' discovery that HITS are factors in the up-regulation and/or induction of amyloid beta precursor processing in mammalian, and principally, neuronal cells, and that the inhibition of the function of such polypeptides is effective in reducing levels of amyloid beta protein peptides. Table 1 below identifies the cDNA, transcript variants of the target gene, protein, and knock-down ("KD") SEQ ID NOs. for the HITS identified in the screening assay of the present invention as modulators of amyloid beta 1-42. The sequences of the cDNA and proteins are found at the end of the specification, and are also available through the listed Genbank accession numbers.

Table 1-1 below identifies the SEQ ID NOs. for protein domain fragments of selected transmembrane proteins of the HITS along with the corresponding Genbank accession numbers. Table 1-1

k< ccession Name Protein Segment Seq ID protein segment

NM_018423 protein kinase STYKl Intracellular domain 801 NM_018423 protein kinase STYKl Transmembrane domain 802 NM_018423 protein kinase STYKl Extracellular domain 803

NM 030770TMPRSS5 Intracellular domain 804

NM 030770TMPRSS5 Transmembrane domain 805

NM 030770TMPRSS5 Extracellular domain 806

NM_002206ITGA7 Intracellular domain 807 NM_002206ITGA7 Transmembrane domain 808 NM_002206ITGA7 Extracellular domain 809 NM_002206ITGA7 Transmembrane domain 810 NM 002206ITGA7 Intracellular domain 811

NM 004440EPHA7 Extracellular domain 812

NM 004440EPHA7 Transmembrane domain 813

NM 004440EPHA7 Intracellular domain 814

NM_002821PTK7 Intracellular domain 815 NM_002821PTK7 Transmembrane domain 816 NM_002821PTK7 Extracellular domain 817 NM_002821PTK7 Transmembrane domain 818 NM 002821 PTK7 Intracellular domain 819

NM_152883PTK7 Intracellular domain 820 NM_152883PTK7 Transmembrane domain 821 NM_152883 PTK7 Extracellular domain 822 NM_152883PTK7 Transmembrane domain 823 NM 152883 PTK7 Intracellular domain 824

NM_152880PTK7 Intracellular domain 825 NM_152880PTK7 Transmembrane domain 826 NM_152880PTK7 Extracellular domain 827 NM_152880PTK7 Transmembrane domain 828 NM 152880PTK7 Intracellular domain 829

NMJ.52881PTK7 Intracellular domain 830 NM_152881PTK7 Transmembrane domain 831 NM 52881PTK7 Extracellular domain 832 NM_152881PTK7 Transmembrane domain 833 NM 152881 PTK7 Intracellular domain 834

NM_152882PTK7 Intracellular domain 835 NM_152882PTK7 Transmembrane domain 836 NM_152882PTK7 Extracellular domain 837 NM_152882PTK7 Transmembrane domain 838 NM 152882PTK7 Intracellular domain 839

NM 006182DDR2 Extracellular domain 840

NM 006182DDR2 Transmembrane domain 841

NM 006182DDR2 Intracellular domain 842

XM_036383ADCY2 Intracellular domain 843 XM 036383ADCY2 Transmembrane domain 844 XM_036383ADCY2 Extracellular domain 845 XM_036383ADCY2 Transmembrane domain 846 XM_036383ADCY2 Intracellular domain 847 XM_036383ADCY2 Transmembrane domain 848 XM_036383ADCY2 Extracellular domain 849 XM_036383ADCY2 Transmembrane domain 850 XM_036383ADCY2 Intracellular domain 851 XM_036383ADCY2 Transmembrane domain 852 XM_036383ADCY2 Extracellular domain 853 XM_036383ADCY2 Transmembrane domain 854 XM 036383 ADCY2 Intracellular domain 855

NM_020546ADCY2 Intracellular domain 856

NM_020546ADCY2 Transmembrane domain 857

NM_020546ADCY2 Extracellular domain 858

NM_020546ADCY2 Transmembrane domain 859

NM_020546ADCY2 Intracellular domain 860

NM_020546ADCY2 Transmembrane domain 861

NM_020546ADCY2 Extracellular domain 862

NM_020546ADCY2 Transmembrane domain 863

NM_020546ADCY2 Intracellular domain 864

NM_020546ADCY2 Transmembrane domain 865

NM_020546ADCY2. Extracellular domain 866

NM_020546ADCY2 Transmembrane domain 867

NM_020546ADCY2 Intracellular domain 868

NM_020546ADCY2 Transmembrane domain 869

NM_020546ADCY2 Extracellular domain 870

NM_020546ADCY2 Transmembrane domain 871

NM_020546ADCY2 Intracellular domain 872

NM_020546ADCY2 Transmembrane domain 873

NM_020546ADCY2 Extracellular domain 874

NM_020546ADCY2 Transmembrane domain 875

NM_020546ADCY2 Intracellular domain 876

NM_020546ADCY2 Transmembrane domain 877

NM_020546ADCY2 Extracellular domain 878

NM_020546ADCY2 Transmembrane domain 879

NM 020546ADCY2 Intracellular domain 880

XM_166593 ADCYl Intracellular domain 881 XM_166593 ADCY1 Transmembrane domain 882 XM_166593 ADCYl Extracellular domain 883 XM_166593 ADCYl Transmembrane domain 884 XM_166593 ADCYl Intracellular domain 885 XM 66593 ADCYl Transmembrane domain 886 XM 166593 ADCYl Extracellular domain 887

NM_021116ADCY1 Intracellular domain 888 NM_021116 ADCYl Transmembrane domain 889 NM_021116 ADCYl Extracellular domain 890 NM_021116ADCY1 Transmembrane domain 891 NM_021116ADCY1 Intracellular domain 892 NM_021116 ADCYl Transmembrane domain 893 NM 021116ADCY1 Extracellular domain 894 NM_021116ADCY1 Transmembrane domain 895 NM_021116ADCY1 Intracellular domain 896 NM_021116ADCY1 Transmembrane domain 897 NM_021116 ADCYl Extracellular domain 898 NM_021116 ADCYl Transmembrane domain 899 NM_021116 ADCYl Intracellular domain 900 NM_021116 ADCYl Transmembrane domain 901 NM_021116 ADCYl Extracellular domain 902 NM_021116ADCY1 Transmembrane domain 903 NM_021116 ADCYl Intracellular domain 904 NM_021116ADCY1 Transmembrane domain 905 NM 021116ADCY1 Extracellular domain 906

NM 002828PTPN2 Extracellular domain 907

NM 002828PTPN2 Transmembrane domain 908

NM 002828PTPN2 Intracellular domain 909

NM_018646TRPV6 Extracellular domain 910 NM_018646TRPV6 Transmembrane domain 911 NM_018646TRPV6 Intracellular domain 912 NM_018646TRPV6 Transmembrane domain 913 NM_018646TRPV6 Extracellular domain 914 NM_018646TRPV6 Transmembrane domain 915 NMJH8646TRPV6 Intracellular domain 916 NM_018646TRPV6 Transmembrane domain 917 NM_018646TRPV6 Extracellular domain 918 NM_018646TRPV6 Transmembrane domain 919 NM_018646TRPV6 Intracellular domain 920 NM H8646TRPV6 Transmembrane domain 921 NM_018646TRPV6 Extracellular domain 922 NM_018646TRPV6 Transmembrane domain 923 NM 018646TRPV6 Intracellular domain 924

NM_014274TRPV6 Intracellular domain 925 NM_014274TRPV6 Transmembrane domain 926 NM H4274TRPV6 Extracellular domain 927 NM_014274TRPV6 Transmembrane domain 928 NM_014274TRPV6 Intracellular domain 929 NM_014274TRPV6 Transmembrane domain 930 NM_014274TRPV6 Extracellular domain 931 NM_014274TRPV6 Transmembrane domain 932 NM_014274TRPV6 Intracellular domain 933 NM H4274TRPV6 Transmembrane domain 934 NM H4274TRPV6 Extracellular domain 935 NM_014274TRPV6 Transmembrane domain 936 NM 014274TRPV6 Intracellular domain 937

As discussed in more detail in the Experimental section below, the present inventors demonstrate that the knockdown of the HITS reduces amyloid beta 1-42 in the conditioned medium of transduced cells. The present invention is based on these findings and the recognition that the HITS are putative drug targets for Alzheimer's disease. One aspect of the present invention is a method based on the aforesaid discovery for identifying a compound that inhibits the processing of amyloid-beta precursor protein in a mammalian cell, and may therefore be useful in reducing amyloid beta peptide levels in a subject. The present method comprises contacting a drug candidate compound with a HIT polypeptide, or a fragment of said polypeptide, and measuring a compound-polypeptide property related to the production of amyloid-beta protein. The "compound-polypeptide property" is a measurable phenomenon chosen by the person of ordinary skill in the art, and based on the recognition that HIT activation and deactivation is a causative factor in the activation and deactivation, respectively, of amyloid beta protein precursor processing, and an increase and decrease, respectively, of amyloid beta peptide levels. The measurable property may range from the binding affinity for a peptide domain of the HIT polypeptide, to the level of any one of a number of cleaved protease substrate levels resulting from the activation or deactivation of the HIT, to a reporter molecule property directly linked to the aforesaid cleaved substrate, and finally to the level of amyloid beta peptide secreted by the mammalian cell contacted with the compound. Depending on the choice of the skilled artisan, the present assay method may be designed to function as a series of measurements, each of which is designed to determine whether the drug candidate compound is indeed acting on HIT to thereby facilitate the amyloid beta peptide pathway. For example, an assay designed to determine the binding affinity of a compound to HIT, or fragment thereof, may be necessary, but not sufficient, to ascertain whether the test compound would be useful for reducing amyloid beta peptide levels when administered to a subject. Nonetheless, such binding information would be useful in identifying a set of test compounds for use in an assay that would measure a different property, further down the biochemical pathway. Such second assay may be designed to confirm that the test compound, having binding affinity for a HIT peptide, actually down-regulates or inhibits HIT function in a mammalian cell. This further assay may measure a cleaved HIT substrate that is a direct consequence of the activation or deactivation of the HIT, or a synthetic reporter system responding thereto. Measuring a different substrate, and/or confirming that the assay system itself is not being affected directly in contrast to the HIT pathway may further validate the assay. In this latter regard, suitable controls should always be in place to insure against false positive readings. The order of taking these measurements is not believed to be critical to the practice of the present invention, which may be practiced in any order. For example, one may first perform a screening assay of a set of compounds for which no information is known respecting the compounds' binding affinity for HIT. Alternatively, one may screen a set of compounds identified as having binding affinity for a HIT peptide domain, or a class of compounds identified as being an inhibitor of a HIT. However, for the present assay to be meaningful to the ultimate use of the drug candidate compounds, a measurement of the cleaved protease substrate(s), the phosphorylated kinase substrate(s), second messenger levels, or the ultimate amyloid beta peptide levels, is necessary. Validation studies including controls, and measurements of binding affinity to HIT are nonetheless useful in identifying a compound useful in any therapeutic or diagnostic application. The present assay method may be practiced in vitro, using one or more of the HIT proteins, or fragments thereof. The amino acid sequences of the preferred HITS, are found in SEQ ID NO: 501-732. The amino acid sequences of exemplary protem domain fragments of selected HITS are SEQ ID NO: 801-937. The binding affinity of the compound with the polypeptide can be measured by methods known in the art, such as using surface plasmon resonance biosensors (Biacore), by saturation binding analysis with a labeled compound (e.g. Scatchard and Lindmo analysis), by differential UV spectre-photometer, fluorescence polarization assay, Fluorometric

Imaging Plate Reader (FLIPR^®) system, Fluorescence resonance energy transfer, and

Bioluminescence resonance energy transfer. The binding affinity of compounds can also be expressed in dissociation constant (Kd) or as IC50 or EC50. The IC50 represents the concentration of a compound that is required for 50% inhibition of binding of another ligand to the polypeptide. The EC50 represents the concentration required for obtaining 50% of the maximum effect in any assay that measures HIT function. The dissociation constant, Kd, is a measure of how well a ligand binds to the polypeptide, it is equivalent to the ligand concentration required to saturate exactly half of the binding-sites on the polypeptide.

Compounds with a high affinity binding have low Kd, IC50 and EC50 values, i.e. in the range of 100 nM to 1 pM; a moderate to low affinity binding relates to a high Kd, IC50 and

EC50 values, i.e. in the micromolar range. The present assay method may also be practiced in a cellular assay, A host cell expressing HIT can be a cell with endogenous expression or a cell over-expressing the HIT e.g. by transduction. hen the endogenous expression of the polypeptide is not sufficient to determine a baseline that can easily be measured, one may use using host cells that over- express HIT. Over-expression has the advantage that the level of the HIT substrate end products is higher than the activity level by endogenous expression. Accordingly, measuring such levels using presently available techniques is easier. In such cellular assay, the biological activity of HIT may be measured by following the production of a cleaved protease substrate, the phosphorylated kinase substrate(s), a second messenger level, each of which measured level depends on the actual HIT being expressed, or the ultimate amyloid beta peptide levels. Such levels may be measured by several different techniques, either directly by ELISA, radioactive or fluorescent technologies. Increased presence of HIT in a cell increases the level of secreted amyloid beta peptides. Conversely, as demonstrated by the present inventors HIT inhibition by siRNA reduces the level of secreted amyloid beta peptides. The present invention further relates to a method for identifying a compound that inhibits amyloid-beta precursor protein processing in a mammalian cell comprising: (a) contacting a compound with a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732, 801-937, (b) determining the binding affinity of the compound to the polypeptide, (c) contacting a population of mammalian cells expressing said polypeptide with the compound that exhibits a binding affinity of at least 10 micromolar, and (d) identifying the compound that inhibits the amyloid-beta precursor protein processing in the cells. A further embodiment of the present invention relates a method to identify a compound that inhibits the amyloid-beta precursor protein processing in a cell, wherein the activity level of the HIT polypeptide is measured by determining the level of amyloid beta peptides. The levels of these peptides may be measured with specific ELISAs using antibodies specifically recognizing the amyloid beta peptide species 1-42 (see e.g. EXAMPLE 1). Secretion of the various amyloid beta peptides may also be measured using antibodies that bind all peptides. Levels of amyloid beta peptides can also be measured by Mass spectrometry analysis. For high-throughput purposes, libraries of compounds may be used such as antibody fragment libraries, peptide phage display libraries, peptide libraries (e.g. LOPAP™, Sigma Aldrich), lipid libraries (BioMol), synthetic compound libraries (e.g. LOPAC™, Sigma Aldrich) or natural compound libraries (Specs, TimTec). Preferred drug candidate compounds are low molecular weight compounds. Low molecular weight compounds, i.e. with a molecular weight of 500 Dalton or less, are likely to have good absorption and permeation in biological systems and are consequently more likely to be successful drug candidates than compounds with a molecular weight above 500 Dalton (Lipinski et al. (1997)). Peptides comprise another preferred class of drug candidate compounds. Peptides may be excellent drug candidates and there are multiple examples of commercially valuable peptides such as fertility hormones and platelet aggregation inhibitors. Natural compounds are another preferred class of drug candidate compound. Such compounds are found in and extracted from natural sources, and which may thereafter be synthesized. The lipids are another preferred class of drug candidate compound. Another preferred class of drug candidate compounds is an antibody. The present invention also provides antibodies directed against HIT. These antibodies may be endogenously produced to bind to the HIT within the cell, or added to the tissue to bind to HIT polypeptide present outside the cell. These antibodies may be monoclonal antibodies or polyclonal antibodies. The present invention includes chimeric, single chain, and humanized antibodies, as well as FAb fragments and the products of a FAb expression library, and Fv fragments and the products of an Fv expression library. In certain embodiments, polyclonal antibodies may be used in the practice of the invention. The skilled artisan knows methods of preparing polyclonal antibodies. Polyclonal antibodies can be raised in a mammal, for example, by one or more injections of an immunizing agent and, if desired, an adjuvant. Typically, the immunizing agent and/or adjuvant will be injected in the mammal by multiple subcutaneous or intraperitoneal injections. Antibodies may also be generated against the intact HIT protein or polypeptide, or against a fragment, derivatives including conjugates, or other epitope of the HIT protein or polypeptide, such as the HIT embedded in a cellular membrane, or a library of antibody variable regions, such as a phage display library. It may be useful to conjugate the immunizing agent to a protein known to be immunogenic in the mammal being immunized. Examples of such immunogenic proteins include but are not limited to keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, and soybean trypsin inhibitor. Examples of adjuvants that may be employed include Freund's complete adjuvant and MPL-TDM adjuvant (monophosphoryl Lipid A, synthetic trehalose dicorynomycolate). One skilled in the art without undue experimentation may select the immunization protocol. In some embodiments, the antibodies may be monoclonal antibodies. Monoclonal antibodies may be prepared using methods known in the art. The monoclonal antibodies of the present invention may be "humanized" to prevent the host from mounting an immune response to the antibodies. A "humanized antibody" is one in which the complementarity determining regions (CDRs) and/or other portions of the light and/or heavy variable domain framework are derived from a non-human immunoglobulin, but the remaining portions of the molecule are derived from one or more human immunoglobulins. Humanized antibodies also include antibodies characterized by a humanized heavy chain associated with a donor or acceptor unmodified light chain or a chimeric light chain, or vice versa. The humanization of antibodies may be accomplished by methods known in the art (see, e.g. Mark and Padlan, (1994) "Chapter 4. Humanization of Monoclonal Antibodies", The Handbook of Experimental Pharmacology Vol. 113, Springer- Verlag, New York). Transgenic animals may be used to express humanized antibodies. Human antibodies can also be produced using various techniques known in the art, including phage display libraries (Hoogenboom and Winter, (1991) J. Mol. Biol. 227:381- 8; Marks et al. (1991). J. Mol. Biol. 222:581-97). The techniques of Cole, et al. and Boerner, et al. are also available for the preparation of human monoclonal antibodies (Cole, et al. (1985) Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77; Boerner, et al (1991). J. Immunol., 147(l):86-95). Techniques known in the art for the production of single chain antibodies can be adapted to produce single chain antibodies to the HIT polypeptides and proteins of the present invention. The antibodies may be monovalent antibodies. Methods for preparing monovalent antibodies are well known in the art. For example, one method involves recombinant expression of immunoglobulin light chain and modified heavy chain. The heavy chain is truncated generally at any point in the Fc region so as to prevent heavy chain cross-linking. Alternatively; the relevant cysteine residues are substituted with another amino acid residue or are deleted so as to prevent cross-linking. Bispecific antibodies are monoclonal, preferably human or humanized, antibodies that have binding specificities for at least two different antigens and preferably for a cell-surface protein or receptor or receptor subunit. In the present case, one of the binding specificities is for one domain of the HIT; the other one is for another domain of the same or different HIT. Methods for making bispecific antibodies are known in the art. Traditionally, the recombinant production of bispecific antibodies is based on the co-expression of two immunoglobulin heavy-chain/light-chain pairs, where the two heavy chains have different specificities (Milstein and Cuello, (1983) Nature 305:537-9). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of ten different antibody molecules, of which only one has the correct bispecific structure. Affinity chromatography steps usually accomplish the purification of the correct molecule. Similar procedures are disclosed in Trauneeker, et al. (1991) EMBO J. 10:3655-9. According to another preferred embodiment, the assay method uses a drug candidate compound identified as having a binding affinity for HITS, and/or has already been identified as having down-regulating activity such as antagonist activity vis-a-vis one or more HIT. Another aspect of the present invention relates to a method for reducing amyloid-beta precursor protein processing in a mammalian cell, comprising by contacting said cell with an expression-inhibiting agent that inhibits the translation in the cell of a polyribonucleotide encoding a HIT polypeptide. A particular embodiment relates to a composition comprising a polynucleotide including at least one antisense strand that functions to pair the agent with the target HIT mRNA, and thereby down-regulate or block the expression of HIT polypeptide. The inhibitory agent preferably comprises antisense polynucleotide, a ribozyme, and a small interfering RNA (siRNA), wherein said agent comprises a nucleic acid sequence complementary to, or engineered from, a naturally-occurring polynucleotide sequence encoding a portion of a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732. A special embodiment of the present invention relates to a method wherein the expression-inhibiting agent is selected from the group consisting of antisense RNA, antisense oligodeoxynucleotide (ODN), a ribozyme that cleaves the polyribonucleotide coding for SEQ ID NO: 501-732, a small interfering RNA (siRNA, preferably shRNA,) that is sufficiently homologous to a portion of the polyribonucleotide coding for SEQ ID NO: 501-732 such that the siRNA, preferably shRNA, interferes with the translation of the HIT polyribonucleotide to the HIT polypeptide. Another embodiment of the present invention relates to a method wherein the expression-inhibiting agent is a nucleic acid expressing the antisense RNA, antisense oligodeoxynucleotide (ODN), a ribozyme that cleaves the polyribonucleotide coding for SEQ ED NO: 501-732, a small interfering RNA (siRNA, preferably shRNA,) that is sufficiently homologous to a portion of the polyribonucleotide coding for SEQ ID NO: 501-732 such that the siRNA, preferably shRNA, interferes with the translation of the HIT polyribonucleotide to the HIT polypeptide. Preferably the expression-inhibiting agent is an antisense RNA, ribozyme, antisense oligodeoxynucleotide, or siRNA, preferably shRNA, comprising a nucleotide sequence complementary to 17-25 contiguous nucleotides of a nucleic acid sequence selected from the group consisting of SEQ ID NO: 201-432. The down regulation of gene expression using antisense nucleic acids can be achieved at the translational or transcriptional level. Antisense nucleic acids of the invention are preferably nucleic acid fragments capable of specifically hybridizing with all or part of a nucleic acid encoding a HIT polypeptide or the corresponding messenger RNA. In addition, antisense nucleic acids may be designed which decrease expression of the nucleic acid sequence capable of encoding a HIT polypeptide by inhibiting splicing of its primary transcript. Any length of antisense sequence is suitable for practice of the invention so long as it is capable of down-regulating or blocking expression of a nucleic acid coding for a HIT. Preferably, the antisense sequence is at least about 17 nucleotides in length. The preparation and use of antisense nucleic acids, DNA encoding antisense RNAs and the use of oligo and genetic antisense is known in the art. _>sι One embodiment of expression-inhibitory agent is a nucleic acid that is antisense to a nucleic acid comprising SEQ ID NO: 201-432. For example, an antisense nucleic acid (e.g. DNA) may be introduced into cells in vitro, or administered to a subject in vivo, as gene therapy to inhibit cellular expression of nucleic acids comprising SEQ ID NO: 201-432. Antisense oligonucleotides preferably comprise a sequence containing from about 17 to about 100 nucleotides and more preferably the antisense oligonucleotides comprise from about 18 to about 30 nucleotides. Antisense nucleic acids may be prepared from about 10 to about 30 contiguous nucleotides selected from the sequences of SEQ ID NO: 201-432, expressed in the opposite orientation. The antisense nucleic acids are preferably oligonucleotides and may consist entirely of deoxyribo-nucleotides, modified deoxyribonucleotides, or some combination of both. The antisense nucleic acids can be synthetic oligonucleotides. The oligonucleotides may be chemically modified, if desired, to improve stability and/or selectivity. Since oligonucleotides are susceptible to degradation by intracellular nucleases, the modifications can include, for example, the use of a sulfur group to replace the free oxygen of the phosphodiester bond. This modification is called a phosphorothioate linkage. Phosphorothioate antisense oligonucleotides are water soluble, polyanionic, and resistant to endogenous nucleases. In addition, when a phosphorothioate antisense oligonucleotide hybridizes to its target site, the RNA-DNA duplex activates the endogenous enzyme ribonuclease (RNase) H, which cleaves the mRNA component of the hybrid molecule. In addition, antisense oligonucleotides with phosphoramidite and polyamide (peptide) linkages can be synthesized. These molecules should be very resistant to nuclease degradation. Furthermore, chemical groups can be added to the 2' carbon of the sugar moiety and the 5 carbon (C-5) of pyrimidines to enhance stabihty and facilitate the binding of the antisense oligonucleotide to its target site. Modifications may include 2'-deoxy, O-pentoxy, O-propoxy, O-methoxy, fluoro, methoxyefhoxy phosphorothioates, modified bases, as well as other modifications known to those of skill in the art. Another type of expression-inhibitory agent that reduces the levels of HITS is ribozymes. Ribozymes are catalytic RNA molecules (RNA enzymes) that have separate catalytic and substrate binding domains. The substrate binding sequence combines by nucleotide complementarity and, possibly, non-hydrogen bond interactions with its target sequence. The catalytic portion cleaves the target RNA at a specific site. The substrate domain of a ribozyme can be engineered to direct it to a specified mRNA sequence. The ribozyme recognizes and then binds a target mRNA through complementary base pairing. Once it is bound to the correct target site, the ribozyme acts enzymatically to cut the target mRNA. Cleavage of the mRNA by a ribozyme destroys its ability to direct synthesis of the corresponding polypeptide. Once the ribozyme has cleaved its target sequence, it is released and can repeatedly bind and cleave at other mRNAs. Ribozyme forms include a hammerhead motif, a hairpin motif, a hepatitis delta virus, group I intron or RNaseP RNA (in association with an RNA guide sequence) motif or Neurospora VS RNA motif. Ribozymes possessing a hammerhead or hairpin structure are readily prepared since these catalytic RNA molecules can be expressed within cells from eukaryotic promoters (Chen, et al. (1992) Nucleic Acids Res. 20:4581-9). A ribozyme of the present invention can be expressed in eukaryotic cells from the appropriate DNA vector. If desired, the activity of the ribozyme may be augmented by its release from the primary transcript by a second ribozyme (Ventura, et al. (1993) Nucleic Acids Res. 21 :3249-55). Ribozymes may be chemically synthesized by combining an oligodeoxyribonucleotide with a ribozyme catalytic domain (20 nucleotides) flanked by sequences that hybridize to the target mRNA after transcription. The oligodeoxyribonucleotide is amplified by using the substrate binding sequences as primers. The amplification product is cloned into a eukaryotic expression vector. Ribozymes are expressed from transcription units inserted into DNA, RNA, or viral vectors. Transcription of the ribozyme sequences are driven from a promoter for eukaryotic RNA polymerase I (pol (I), RNA polymerase II (pol II), or RNA polymerase IH (pol DI). Transcripts from pol II or pol HI promoters will be expressed at high levels in all cells; the levels of a given pol II promoter in a given cell type will depend on nearby gene regulatory sequences. Prokaryotic RNA polymerase promoters are also used, providing that the prokaryotic RNA polymerase enzyme is expressed in the appropriate cells (Gao and Huang, (1993) Nucleic Acids Res. 21:2867-72). It has been demonstrated that ribozymes expressed from these promoters can function in mammalian cells (Kashani-Sabet, et al. (1992) Antisense Res. Dev. 2:3-15). A particularly preferred inhibitory agent is a small interfering RNA (siRNA, preferably shRNA,). siRNA, preferably shRNA, mediate the post-transcriptional process of gene silencing by double stranded RNA (dsRNA) that is homologous in sequence to the silenced RNA. siRNA according to the present invention comprise a sense strand of 1 *25 nucleotides selected from the group of sequences described in SEQ ID NO: 201-432 and an antisense strand of 17-25 nucleotides complementary to the sense strand. Exemplary sense strand sequences are described as the KD target sequences of SEQ ID NO: 1-141. The most preferred siRNA comprises sense and anti-sense strands that are 100 per cent complementary to each other and the target polynucleotide sequence. Preferably the siRNA further comprises a loop region linking the sense and the antisense strand. A self-complementing single stranded siRNA molecule polynucleotide according to the present invention comprises a sense portion and an antisense portion connected by a loop region linker. Preferably, the loop region sequence is 4-30 nucleotides long, more preferably 5-15 nucleotides long and most preferably 8 nucleotides long. In a most preferred embodiment the linker sequence is UUGCUAU (SEQ ID NO: 142). Self-complementary single stranded siRNAs form hairpin loops and are more stable than ordinary dsRNA. In addition, they are more easily produced from vectors. Analogous to antisense RNA, the siRNA can be modified to confirm resistance to nucleolytic degradation, or to enhance activity, or to enhance cellular distribution, or to enhance cellular uptake, such modifications may consist of modified internucleoside linkages, modified nucleic acid bases, modified sugars and or chemical linkage the siRNA to one or more moieties or conjugates. The nucleotide sequences are selected according to siRNA designing rules that give an improved reduction of the target sequences compared to nucleotide sequences that do not comply with these siRNA designing rules (For a discussion of these rules and examples of the preparation of siRNA, WO2004094636, published November 4, 2004, and UA20030198627, are hereby incorporated by reference). The present invention also relates to compositions, and methods using said compositions, comprising a DNA expression vector capable of expressing a polynucleotide capable of inhibiting amyloid beta protein precursor processing and described hereinabove as an expression inhibition agent. A special aspect of these compositions and methods relates to the down-regulation or blocking of the expression of a HIT polypeptide by the induced expression of a polynucleotide encoding an intracellular binding protein that is capable of selectively interacting with the HIT polypeptide. An intracellular binding protein includes any protein capable of selectively interacting, or binding, with the polypeptide in the cell in which it is expressed and neutralizing the function of the polypeptide. Preferably, the intracellular binding protein is a neutralizing antibody or a fragment of a neutralizing antibody having binding affinity to an epitope of the polypeptide of SEQ ID NO: 501-732, 801-937. More preferably^ the intracellular binding protein is a single chain antibody. A special embodiment of this composition comprises the expression-inhibiting agent selected from the group consisting of antisense RNA, antisense oligodeoxynucleotide (ODN), a ribozyme that cleaves the polyribonucleotide coding for SEQ ID NO: 501-732, and a small interfering RNA (siRNA) that is sufficiently homologous to a portion of the polyribonucleotide coding for SEQ ID NO: 501-732 such that the siRNA interferes with the translation of the HIT polyribonucleotide to the HIT polypeptide, The polynucleotide expressing the expression-inhibiting agent is preferably included within a vector. The polynucleic acid is operably linked to signals enabling expression of the nucleic acid sequence and is introduced into a cell utilizing, preferably, recombinant vector constructs, which will express the antisense nucleic acid once the vector is introduced into the cell. A variety of viral-based systems are available, including adenoviral, retroviral, adeno-associated viral, lentiviral, herpes simplex viral or a sendaviral vector systems, and all may be used to introduce and express polynucleotide sequence for the expression-inhibiting agents in target cells. Preferably, the viral vectors used in the methods of the present invention are replication defective. Such replication defective vectors will usually pack at least one region that is necessary for the replication of the virus in the infected cell. These regions can either be eliminated (in whole or in part), or be rendered non-functional by any technique known to a person skilled in the art. These techniques include the total removal, substitution, partial deletion or addition of one or more bases to an essential (for replication) region. Such techniques may be performed in vitro (on the isolated DNA) or in situ, using the techniques of genetic manipulation or by treatment with mutagenic agents. Preferably, the replication defective virus retains the sequences of its genome, which are necessary for encapsidating, the viral particles. In a preferred embodiment, the viral element is derived from an adenovirus.

Preferably, the vehicle includes an adenoviral vector packaged into an adenoviral capsid, or a functional part, derivative, and/or analogue thereof. Adenovirus biology is also comparatively well known on the molecular level. Many tools for adenoviral vectors have been and continue to be developed, thus making an adenoviral capsid a preferred vehicle for incorporating in a library of the invention. An adenovirus is capable of infecting a wide variety of cells. However, different adenoviral serotypes have different preferences for cells. To combine and widen the target cell population that an adenoviral capsid of the invention can enter in a preferred embodiment, the vehicle includes adenoviral fiber proteins from at least two adenoviruses. Preferred adenoviral fiber protein sequences are serotype 17, 45 and 51. Techniques or construction and expression of these chimeric vectors are disclosed in US Published Patent Applications 20030180258 and 20040071660, hereby incorporated by reference. In a preferred embodiment, the nucleic acid derived from an adenovirus includes the nucleic acid encoding an adenoviral late protein or a functional part, derivative, and/or analogue thereof. An adenoviral late protein, for instance an adenoviral fiber protein, may be favorably used to target the vehicle to a certain cell or to induce enhanced delivery of the vehicle to the cell. Preferably, the nucleic acid derived from an adenovirus encodes for essentially all adenoviral late proteins, enabling the formation of entire adenoviral capsids or functional parts, analogues, and/or derivatives thereof. Preferably, the nucleic acid derived from an adenovirus includes the nucleic acid encoding adenovirus E2A or a functional part, derivative, and/or analogue thereof. Preferably, the nucleic acid derived from an adenovirus includes the nucleic acid encoding at least one E4-region protein or a functional part, derivative, and/or analogue thereof^ which facilitates, at least in part, replication of an adenoviral derived nucleic acid in a cell. The adenoviral vectors used in the examples of this application are exemplary of the vectors useful in the present method of treatment invention. Certain embodiments of the present invention use retroviral vector systems. Retroviruses are integrating viruses that infect dividing cells, and their construction is known in the art. Retroviral vectors can be constructed from different types of retrovirus, such as, MoMuLV ("murine Moloney leukemia virus" MSV ("murine Moloney sarcoma virus"), HaSV ("Harvey sarcoma virus"); SNV ("spleen necrosis virus"); RSV ("Rous sarcoma virus") and Friend virus. Lentiviral vector systems may also be used in the practice of the present invention. Retroviral systems and herpes virus system may be preferred vehicles for transfection of neuronal cells. In other embodiments of the present invention, adeno-associated viruses ("AAV") are utilized. The AAV viruses are DNA viruses of relatively small size that integrate, in a stable and site-specific manner, into the genome of the infected cells. They are able to infect a wide spectrum⁵' of cells without inducing any effects on cellular growth, morphology or differentiation, and they do not appear to be involved in human pathologies. In the vector construction, the polynucleotide agents of the present invention may be linked to one or more regulatory regions. Selection of the appropriate regulatory region or regions is a routine matter, wimin the level of ordinary skill in the art. Regulatory regions include promoters, and may include enhancers, suppressors, etc. Promoters that may be used in the expression vectors of the present invention include both constitutive promoters and regulated (inducible) promoters. The promoters may be prokaryotic or eukaryotic depending on the host. Among the prokaryotic (including bacteriophage) promoters useful for practice of this invention are lac, lacZ, T3, T7, lambda P.sub.r, P.sub.l, and trp promoters. Among the eukaryotic (including viral) promoters useful for practice of this invention are ubiquitous promoters (e.g. HPRT, vimentin, actin, tubulin), intermediate filament promoters (e.g. desmin, neurofilaments, keratin, GFAP), therapeutic gene promoters (e.g. MDR type, CFTR, factor Vπi), tissue-specific promoters (e.g. actin promoter in smooth muscle cells, or Fit and Flk promoters active in endothelial cells), including animal transcriptional control regions, which exhibit tissue specificity and have been utilized in transgenic animals: elastase I gene control region which is active in pancreatic acinar cells (Swift, et al. (1984) Cell 38:639-46; Ornitz, et al. (1986) Cold Spring Harbor Symp. Quant. Biol. 50:399-409; MacDonald, (1987) Hepatology 7:425-515); insulin gene control region which is active in pancreatic beta cells (Hanahan, (1985) Nature 315:115-22), immunoglobulin gene control region which is active in lymphoid cells (Grosschedl, et al. (1984) Cell 38:647-58; Adames, et al. (1985) Nature 318:533-8; Alexander, et al. (1987) Mol. Cell. Biol. 7:1436-44), mouse mammary tumor virus control region which is active in testicular, breast, lymphoid and mast cells (Leder, et al. (1986) Cell 45:485-95), albumin gene control region which is active in liver (Pinkert, et al. (1987) Genes and Devel. 1:268-76), alpha-fetoprotein gene control region which is active in liver (Krumlauf, et al. (1985) Mol. Cell. Biol., 5:1639-48; Hammer, et al. (1987) Science 235:53-8), alpha 1-antitrypsin gene control region which is active in the liver (Kelsey, et al. (1987) Genes and Devel., 1: 161-71), beta-globin gene control region which is active in myeloid cells (Mogram, et al. (1985) Nature 315:338-40; Kollias, et al. (1986) Cell 46:89- 94), myelin basic protein gene control region which is active in oligodendrocyte cells in the brain (Readhead, et al. (1987) Cell 48:703-12), myosin light chain-2 gene control region which is active in skeletal muscle (Sani, (1985) Nature 314.283-6), and gonadotropic releasing hormone gene control region which is active in the hypothalamus (Mason, et al. (1986) Science 234:1372-8). Other promoters which may be used in the practice of the invention include promoters which are preferentially activated in dividing cells, promoters which respond to a stimulus

(e.g. steroid hormone receptor, retinoic acid receptor), tetracycline-regulated transcriptional modulators, cytomegalovirus immediate-early, retroviral LTR, metøllothionein, SV-40, Ela, and MLP promoters. Additional vector systems include the non-viral systems that facilitate introduction of polynucleotide agents into a patient. For example, a DNA vector encoding a desired sequence can be introduced in vivo by lipofection. Synthetic cationic lipids designed to limit the difficulties encountered with Uposome-mediated transfection can be used to prepare liposomes for in vivo transfection of a gene encoding a marker (Feigner, et. al. (1987) Proc. Natl. Acad Sci. USA 84:7413-7); see Mackey, et al. (1988) Proc. Natl. Acad. Sci. USA 85:8027-31; Ulmer, et al. (1993) Science 259:1745-8). The use of cationic lipids may promote encapsulation of negatively charged nucleic acids, and also promote fusion with negatively charged cell membranes (Feigner and Ringold, (1989) Nature 337:387-8). Particularly useful lipid compounds and compositions for transfer of nucleic acids are described in International Patent Publications WO 95/18863 and WO 96/17823, and in U.S. Pat. No. 5,459,127. The use of lipofection to introduce exogenous genes into the specific organs in vivo has certain practical advantages and directing transfection to particular cell types would be particularly advantageous in a tissue with cellular heterogeneity, for example, pancreas, liver, kidney, and the brain. Lipids may be chemically coupled to other molecules for the purpose of targeting. Targeted peptides, e.g., hormones or neurotransmitters, and proteins for example, antibodies, or non-peptide molecules could be coupled to liposomes chemically. Other molecules are also useful for facilitating transfection of a nucleic acid in vivo, for example, a cationic oligopeptide (e.g., International Patent Publication WO 95/21931), peptides derived from DNA bmding proteins (e.g., International Patent Publication WO 96/25508), or a cationic polymer (e.g., International Patent Publication WO 95/21931). It is also possible to introduce a DNA vector in vivo as a naked DNA plasmid (see U.S. Pat. Nos. 5,693,622, 5,589,466 and 5,580,859). Naked DNA vectors for therapeutic purposes can be introduced into the desired host cells by methods known in the art, e.g., transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, use of a gene gun, or use of a DNA vector transporter (see, e.g., Wilson, et al. (1992) J. Biol. Chem 267:963-7; Wu and Wu, (1988) J. Biol. Chem. 263:14621-4; Hartmut, et al. Canadian Patent Application No. 2,012,311, filed Mar. 15, 1990; Williams, et al (1991). Proc. Natl. Acad. Sci. USA 88:2726-30). Receptor-mediated DNA delivery approaches can also be used (Curiel, et al. (1992) Hum. Gene Ther. 3:147- 54; Wu andWu, (1987) J. Biol. Chem. 262:4429-32). The present invention also provides biologically compatible compositions comprising the compounds identified as HIT inhibitors, and the expression-inhibiting agents as described hereinabove. A biologically compatible composition is a composition, that may be solid, liquid, gel, or other form, in which the compound, polynucleotide, vector, and antibody of the invention is maintained in an active form, e.g., in a form able to effect a biological activity.

For example, a compound of the invention would have inverse agonist or antagonist activity on the HIT; a nucleic acid would be able to replicate, translate a message, or hybridize to a complementary mRNA of a HIT; a vector would be able to transfect a target cell and expression the antisense, antibody, ribozyme or siRNA as described hereinabove; an antibody would bind a HIT polypeptide domain. A preferred biologically compatible composition is an aqueous solution that is buffered using, e.g., Tris, phosphate, or HEPES buffer, containing salt ions. Usually the concentration of salt ions will be similar to physiological levels. Biologically compatible solutions may include stabilizing agents and preservatives. In a more preferred embodiment, the biocompatible composition is a pharmaceutically acceptable composition. Such compositions can be formulated for administration by topical, oral, parenteral, intranasal, subcutaneous, and intraocular, routes. Parenteral a<3ministration is meant to include intravenous injection, intramuscular injection, intraarterial injection or infusion techniques. The composition may be administered parenterally in dosage unit formulations containing standard, well-known non-toxic physiologically acceptable carriers, adjuvants and vehicles as desired. A particularly preferred embodiment of the present composition invention is a cognitive-enhancing pharmaceutical composition comprising a therapeutically effective amount of an expression-inhibiting agent as described hereinabove, in admixture with a pharmaceutically acceptable carrier. Another preferred embodiment is a pharmaceutical composition for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to the condition, comprising an effective amyloid beta peptide inhibiting amount of a HIT antagonist or inverse agonist, its pharmaceutically acceptable salts, hydrates, solvates, or prodrugs thereof in admixture with a pharmaceutically acceptable carrier. Preferred HIT antagonist compounds are known antagonists of the HITS, for example, the known antagonists of the HT3RB protein, such as the l,2,3,9-tetrahydro-3- imidazol-l-ylmethyl-4H-carbazol-4-ones disclosed in US Patent No. 4,695,578, hereby incorporated by reference, and most preferably the compound, ondansetron; the indazolyl carboxylic acid amides and preferably the compound, granisetron, disclosed in US Patent No. 4,886,808; the esters of hexahydro-8-hydroxy-2,6-methano-2H-quinoUzin-3-(4H)-one, preferably, the antagonist, (2,6,8,9ab)-octahydro-3-oxo-2,6-methano-2H-quinoKzin-8-yl-lH- indole-3-carboxylate monomethanesulfonate, monohydrate ("hydrodolasetron") disclosed in US Patent No. 4906755, hereby incorporated by reference; and the antagonist, endo-8- methyl-8-azabicyclo[3.2.1]oct-3-ol Indol-3-yl-carboxylate hydrochloride, ("tropisetron"). Pharmaceutical compositions for oral administration can be formulated using pharmaceutically acceptable carriers well known in the art in dosages suitable for oral administration. Such carriers enable the pharmaceutical compositions to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like, for ingesrion by the patient. Pharmaceutical compositions for oral use can be prepared by combining active compounds with solid excipient, optionally grinding a resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries, if desired, to obtain tablets or dragee cores. Suitable excipients are carbohydrate or protein fillers, such as sugars, including lactose, sucrose, mannitol, or sorbitol; starch from corn, wheat, rice, potato, or other plants; cellulose, such as methyl cellulose, hydroxypropylmethyl-cellulose, or sodium carboxymethyl-cellulose; gums mcluding arabic and tragacanth; and proteins such as gelatin and collagen. If desired, disintegrating or solubihzing agents may be added, such as the cross-linked polyvinyl pyrrolidone, agar, alginic acid, or a salt thereof, such as sodium alginate. Dragee cores may be used in conjunction with suitable coatings, such as concentrated sugar solutions, which may also contain gum arabic, talc, polyvinyl- pyrrolidone, carbopol gel, polyethylene glycol, and or titanium dioxide, lacquer solutions, and suitable organic solvents or solvent mixtures. Dyestuffs or pigments may be added to the tablets or dragee coatings for product identification or to characterize the quantity of active compound, i.e., dosage. Pharmaceutical preparations that can be used orally include push-fit capsules made of gelatin, as well as soft, sealed capsules made of gelatin and a coating, such as glycerol or sorbitol. Push-fit capsules can contain active ingredients mixed with filler or binders, such as lactose or starches, lubricants, such as talc or magnesium stearate, and, optionally, stabilizers. In soft capsules, the active compounds may be dissolved or suspended in suitable liquids, such as fatty oils, liquid, or liquid polyethylene glycol with or without stabilizers. Preferred sterile injectable preparations can be a solution or suspension in a non-toxic parenterally acceptable solvent or diluent. Examples of pharmaceutically acceptable carriers are saline, buffered saline, isotonic saline (e.g. monosodium or disodium phosphate, sodium, potassium; calcium or magnesium chloride, or mixtures of such salts), Ringer's solution, dextrose, water, sterile water, glycerol, ethanol, and combinations thereof 1,3-butanediol and sterile fixed oils are conveniently employed as solvents or suspending media. Any bland fixed oil can be employed including synthetic mono- or di-glycerides. Fatty acids such as oleic acid also find use in the preparation of injectables. The composition medium can also be a hydrogel, which is prepared from any biocompatible or non-cytotoxic homo- or hetero-polymer, such as a hydrophilic polyacrylic acid polymer that can act as a drug absorbing sponge. Certain of them, such as, in particular, those obtained from ethylene and/or propylene oxide are commercially available. A hydrogel can be deposited directly onto the surface of the tissue to be treated, for example during surgical intervention. Embodiments of pharmaceutical compositions of the present invention comprise a replication defective recombinant viral vector encoding the polynucleotide inhibitory agent of the present invention and a transfection enhancer, such as poloxamer. An example of a poloxamer is Poloxamer 407, which is commercially available (BASF, Parsippany, N.J.) and is a non-toxic, biocompatible polyol. A poloxamer impregnated with recombinant viruses may be deposited directly on the surface of the tissue to be treated, for example during a surgical intervention. Poloxamer possesses essentially the same advantages as hydrogel while having a lower viscosity. The active expression-inhibiting agents may also be entrapped in microcapsules prepared, for example, by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly-(methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences (1980) 16th edition, Osol, A. Ed. Sustained-release preparations may be prepared. Suitable examples of sustained- release preparations include semi-permeable matrices of solid hydrophobic polymers containing the antibody, which matrices are in the form of shaped articles, e.g. films, or microcapsules. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and gamma-ethyl-L-glutamate, non- degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™, (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(-)-3-hydroxybutyric acid. While polymers such as ethylene-vinyl acetate and lactic acid-glycolic acid enable release of molecules for over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated antibodies remain in the body for a long time, they may denature or aggregate as a result of exposure to moisture at 37°C, resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular S-S bond formation through thio-disulfide interchange, stabilization may be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing specific polymer matrix compositions. The present invention also provides methods of inhibiting the processing of amyloid- beta precursor protein in a subject suffering or susceptible to the abnormal processing of said protein, which comprise the administration to said subject a therapeutically effective amount of an expression-inhibiting agent of the invention. Another aspect of the present method invention is the treatment or prevention of a condition involving cognitive impairment or a susceptibility to the condition. A special embodiment of this invention is a method wherein the condition is Alzheimer's disease. As defined above, therapeutically effective dose means that amount of protein, polynucleotide, peptide, or its antibodies, agonists or antagonists, which ameliorate the symptoms or condition. Therapeutic efficacy and toxicity of such compounds can be deteπnined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., ED50 (the dose therapeutically effective in 50% of the population) and LD50 (the dose lethal to 50% of the population). The dose ratio of toxic to therapeutic effects is the therapeutic index, and it can be expressed as the ratio, LD50/ED50. Pharmaceutical compositions that exhibit large therapeutic indices are preferred. The data obtained from cell culture assays and animal studies is used in formulating a range of dosage for human use.

The dosage of such compounds lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage varies within this range depending upon the dosage form employed, sensitivity of the patient, and the route of administration. For any compound, the therapeutically effective dose can be estimated initially either in cell culture assays or in animal models, usually mice, rabbits, dogs, or pigs. The animal model is also used to achieve a desirable concentration range and route of administration. Such information can then be used to determine useful doses and routes for administration in humans. The exact dosage is chosen by the individual physician in view of the patient to be treated. Dosage and administration are adjusted to provide sufficient levels of the active moiety or to maintain the desired effect. Additional factors which may be taken into account include the severity of the disease state, age, weight and gender of the patient; diet, desired duration of treatment, method of administration, time and frequency of administration, drug combination^), reaction sensitivities, and tolerance/response to therapy. Long acting pharmaceutical compositions might be administered every 3 to 4 days, every week, or once every two weeks depending on half-life and clearance rate of the particular formulation. The pharmaceutical compositions according to this invention may be administered to a subject by a variety of methods. They may be added directly to target tissues, complexed with cationic lipids, packaged within liposomes, or delivered to target cells by other methods known in the art. Localized adrninistration to the desired tissues may be done by catheter, infusion pump or stent. The DNA, DNA/vehicle complexes, or the recombinant virus particles are locally administered to the site of treatment. Alternative routes of delivery include, but are not limited to, intravenous injection, intramuscular injection, subcutaneous injection, aerosol inhalation, oral (tablet or pill form), topical, systemic, ocular, intraperitoneal and/or intrathecal delivery. Examples of ribozyme delivery and administration are provided in Sullivan et al. WO 94/02595. Antibodies according to the invention may be delivered as a bolus only, infused over time or both administered as a bolus and infused over time. Those skilled in the art may employ different formulations for polynucleotides than for proteins. Similarly, delivery of polynucleotides or polypeptides will be?specific to particular cells, conditions, locations, etc. As discussed hereinabove, recombinant viruses may be used to introduce DNA encoding polynucleotide agents useful in the present invention. Recombinant viruses according to the invention are generally formulated and administered in the form of doses of between about 10⁴ and about 10¹⁴ pfu. In the case of AAVs and adenoviruses, doses of from about 10⁶ to about 10¹¹ pfu are preferably used. The term pfu ("plaque-forming unit") corresponds to the infective power of a suspension of virions and is determined by infecting an appropriate cell culture and measuring the number of plaques formed. The techniques for determining the pfu titre of a viral solution are well documented in the prior art. Still another aspect or the invention relates to a method for diagnosing a pathological condition involving cognitive impairment or a susceptibility to the condition in a subject, comprising determining the amount of polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NO: 501-732, 801-937 in a biological sample, and comparing the amount with the amount of the polypeptide in a healthy subject, wherein an increase of the amount of polypeptide compared to the healthy subject is indicative of the presence of the pathological condition. Experimental Section

EXAMPLE 1 : Screening for Target Genes that Modulate Amyloid Beta 1-42 Levels. To identify novel drug targets that change the APP processing, stable cell lines over expressing APP are made by transfecting Hek293 or SH-SY5Y cells with APP770wt cDNA cloned into pcDNA3.1, followed by selection with G418 for 3 weeks. At this time point colonies are picked and stable clones are expanded and tested for their secreted amyloid-beta peptide levels. The cell lines designated as "Hek293 APPwt" and "SH-SY5Y APPwt" are used in the following examples. ELISA Methodology: The ELISA plate is prepared by coating with a capture antibody (JRF/cAbeta42/26) (the antibody recognizes a specific epitope on the C-terminus of Abeta 1-42; obtained from M Mercken, Johnson and Johnson Pharmaceutical Research and Development, B-2340 Beerse, Belgium) overnight in buffer 42 (Table 2) at a concentration of 2.5 μg/ml. The excess capture antibody is washed away me next morning with PBS and the ELISA plate is then blocked overnight with casein buffer (see Table 2) at 4°C. Upon removal of the blocking buffer, 30 μl of the sample is transferred to the ELISA plate and incubated overnight at 4°C. After extensive washing with PBS-Tween20 and PBS, 30 μl of the horseradish peroxidase (HRP) labeled detection antibody (Peroxidase Labeling Kit, Roche), JRF/AbetaN/25-HRP (obtained from M Mercken, Johnson and Johnson Pharmaceutical Research and Development, B-2340 Beerse, Belgium) is diluted 1/5000 in buffer C (see Table 2) and added to the wells for another 2h. Following the removal of excess detection antibody by a wash with PBS-Tween20 and PBS, HRP activity is detected via addition of luminol substrate (Roche), which is converted into a chemiluminescent signal by the HRP enzyme. Table 2

PBST PBS lx with 0.05% Tween 20

The assay is performed as follows. SH-SY5Y APPwt cells are seeded in collagen- coated plates in 50 μl, at a cell density of 15000 cells/well (384 well plate) in DMEM 10%FBS containing lμM 9 cis-retinoic acid. 48 h later, 10 μl of fresh DMEM 10%FBS containing 1 μM 9 cis-retinoic acid is added and the cells are infected with 3 μl of adenovirus containing the knock down sequences of the siRNA expressing adenoviral library (corresponding to an average multiplicity of infection (MOI) of 700) and an adenovirus harboring the APPsw cDNA at an MOI of 500. The following day, the virus is washed away with 80 μl DMEM 10%FBS containing lμM 9 cis-retinoic acid and 80 μl DMEM 10%FBS containing lμM 9 cis-retinoic acid is added to the cells. After 96 h, the medium is refreshed with 80 μl DMEM 10%FBS containing lμM 9 cis-retinoic acid and 0.025 mM Hepes. Amyloid beta peptides are allowed to accumulate during 48h. In order to validate the assay, adenoviruses containing BACEl (positive control), ALPL and RunX2 (both negative control) knock down sequences are infected at an MOI of 2000 and 500 in SH-SY5Y cells super infected with an adenovirus overexpressing APPsw at an MOI of 500. As is shown in Figure 2, the BACE knock down sequence reduced amyloid beta 1-42 levels compared to the ALPL and RunX2 knock down sequences. To further evaluate the assay in screening mode, a control plate, containing adenoviruses harboring knock down sequences for BACEl, PSEN1, APHIB, GL2 and ALPL and eGFP knock in viruses, was tested. The BACEl and APHIB knock down viruses clearly show a reduced level of amyloid beta 1-42 compared to the negative controls, as expected (Figure 3). When the cut off value is calculated using the formula AVERAGE - (2.3 x STDEV) based upon all data points of the negative controls, all BACEl and APHIB knock down viruses score positive in the assay. This is contrary to the PSEN1 knock down viruses, which are less effective in reducing the amyloid beta 1 -42 levels. During the screening of the adenoviral knock down library in the SH-SY5Y cells infected with an adenovirus overexpressing APPsw, a number of genes are identified as modulators of APP processing. Knocking down the levels of these genes show a reduction of amyloid beta 1-42 levels. Table 3 presents the results of an amyloid beta (Abeta) ELISA 1- 42 screening of the adenoviral-based Knockdown library in SH-SY5Y cells overexpressing APPsw. The average and standard deviation of all data points are taken and HITS are selected corresponding to those knock down sequences that score lower than (AVERAGE (2.3 x STDEV)). The data below are represented as times STDEV. Table 3

The gene sequences that are identified in the aforesaid screen as involved in the up- regulation of amyloid beta 1-42 are hsted as the HITS in Table 1 above. The "hit" ID Nos. in Tables 1 and 3 correlate the HIT information in Table 1 with the assay results in Table 3 EXAMPLE 2: Reduction of Amyloid Beta 1-42 Levels via Knock-down of the Expression of Exemplary HITS. The effect of an antagonist can be mimicked through the use of siRNA-based strategies, which result in decreased expression levels of the targeted protein. HEK293 APPwt cells are transfected with a pool of siRNAs (Table 4) targeted against selected HITS, and the controls, eGFP, GLP and BACEl using Oligofectemine transfection reagent. 24 hours after transfection, medium is refreshed and the cells are allowed to accumulate amyloid beta peptides in the conditioned medium for an additional 24 hours prior to analysis with the Abeta 1-42 ELISA described above. Table 4

The data show that siRNA targeted against the HITS reduce amyloid beta 1-42 levels compared to the control conditions (Figures 4 and 5). In conclusion, these data show that the identified polypeptides according to the present invention modulate the levels of secreted amyloid beta.

EXAMPLE 4: HITS Expression in Human Brain Tissue Upon identification of a HIT involved of APP processing, its expression in the tissue and cells of interest is evaluated. This can be achieved by measuring RNA and/or protein levels. In recent years, RNA levels are being quantified through real time PCR technologies, whereby the RNA is first transcribed to cDNA and then the amphfication of the cDNA of interest is monitored during a PCR reaction. The amplification plot and the resulting Ct value are indicators for the amount of RNA present in the sample. To assess whether the HITS cDNA are expressed in the human brain, real time PCR with GAPDH specific primers and specific primers for polynucleotides coding for the HITS are performed on human total brain, human cerebral cortex, and human hippocampal total RNA (BD Biosciences). GAPDH RNA is detected with a Taqman probe, while for the HITS polynucleotides SybrGreen is used. 40 ng of RNA is transcribed to DNA using the MultiScribe Reverse Transcriptase (50 U/μl) enzyme (Applied BioSystems). The resulting cDNA is amplified with AmpliTaq Gold DNA polymerase (Applied BioSystems) during 40 cycles using an ABI PRISM® 7000 Sequence Detection System. Total RNA isolated from rat primary neurons and human total brain, cerebral cortex and hippocampal is analyzed, via quantitative real time PCR, for the presence of the HITS cDNA.

Amplification of the transcript was detected via SybrGreen which results in a fluorescent signal upon intercalation in double stranded DNA. Table 5 identifies the transcripts used in the analyses for the listed HITS. Table 6 identifies the Ct values determined in this analysis for a sample of the HITS indicating that RNA corresponding to the expression of these HITS are detected in all RNA samples. To gain more insight into the specific cellular expression, immvmohistochemistry (protein level) and/or in situ hybridization (RNA level) are carried out on sections from a human normal and Alzheimer's brain hippocampal, cortical and subcortical structures. These results indicate whether expression occurs in neurons, microglia cells or astrocytes. The comparison of diseased tissue with healthy tissue, teaches us whether the polypeptides of the invention are expressed in the diseased tissue and whether their expression level is changed compared to the non-pathological situation.

Table 5: Primer sequences used in the real time PCR analysis

Homo Sapiens PIK4CA_Hs_Rev GCACATAGCCCATCTTGTCGTA

PU 4CA Mus Museums PIK4CA_Mm_For TCCGGATGCCATTCTGTTCT Mus Musculus PIK4CA_Mm_Rev CACATAGCCCATCTTGTCATATCTG

EPHA7 Homo Sapiens EPHA7_Hs_For GGTTGCTGTAGCTGGGACCAT Homo Sapiens EPHA7_Hs_Rev AAGTAAAGCTCTTCATCGCCTTCT EPHA7 Mm For GAGCAGATAGTCGGAATTCTAGACA

EPHA7 Mus Musculus A Mus Musculus EPHA7_Mm_Rev AGAGGGCTTAAGGGTCTACTACAA

MAP2K5 Homo Sapiens MAP2K5_Hs_For TTCATCACTCAGTGTATGCGAAAA Homo Sapiens MAP2K5_Hs_Rev AACGGGTGGCCCATCAAT

MAP2K5 Mus Musculus MAP2K5_Mm_For CGACGACAGCGTTTGAATATGA MAP2K5_Mm_Re GTGGAATAATAGTAGGACAGCATTG Mus Musculus v C

AVPR2 Homo Sapiens AVPR2_Hs_For ΓGCAGATGGTGGGCATGTAT Homo Sapiens AVPR2_Hs_Rev GCATGGGACGGCAGATG AVPR2 Mus Musculus AVPR2_Mm_For ATGATCCTGGCCATGACACTAGA Mus Musculus AVPR2_Mm_Rev AGCTGAGGCAGGCTGAGAAG PTGER4 Homo Sapiens PTGER4_Hs_For GCCGAGATCCAGATGGTCAT Homo Sapiens PTGER4_Hs_Rev ΓGGCTGATATAACTGGTTGACGAA CSNK1G3 Homo Sapiens CSNKlG3_Hs_For CTGGATTGGTAAACAGTTGCCTACT CSNKlG3_Hs_Re GTGGTCTGCCGACTGGTTTT Homo Sapiens v CSNKlG3_Mm_F TGACACATTAAAAGAGAGGTATCAG

CSNK1G3 Mus Musculus or AAAA CSNKlG3_Mm_R ΓGCCATTTCTTCTGGGAAGTTC Mus Musculus ev

MAP4K2 Homo Sapiens MAP4K2_Hs_For CTGTTACTCGGGACCAGTTCCT Homo Sapiens MAP4K2_Hs_Rev GCACGTTGTTCACGCAGTAGA MAP4K2 Mus Musculus MAP4K2_Mm_ For CATCCCCAGGCGCTTTG MAP4K2_Mm_Re AGGAACGTACTGCCGGTATAGG Mus Musculus v

P1P5K2A Homo Sapiens PD?5K2A_Hs_For AAAGGATGTTGAGTTTCTGGCCC Homo Sapiens PD?5K2A_Hs_rev ATCGTTCTCCTCACACTCCACTTC PIP5K2A Mus Musculus PD?5K2A_Mm_ For GTCGAGTTCCTTGCACAGTTAAAA PIP5K2A_Mm_Re GCTCGCTCCACATCGTGAAT Mus Musculus v

CCR3 Homo Sapiens CCR3_Hs_For TGACAGAGGTGATCGCCTACTC Homo Sapiens CCR3_Hs_Rev CCGGAACCTCTCTCCAACAA

CCR3 Mus Musculus CCR3_Mm_For CCGTACAACCTGGTTCTCCTTT Mus Musculus CCR3_Mm_Rev CATGGCCAGGTCCAGATGTT

PRKG2 Homo Sapiens PRKG2_Hs_For CAAGGAGAACCAGGAAACCATATC Homo Sapiens PRKG2_Hs_Rev AGGGATGGAGGACAGCAATTT

PRKG2 Mus Musculus PRKG2_Mm_For GATGCCGATGGCTACCTTAAGT Mus Musculus PRKG2_Mm_Rev GTCCCACAGAATGTCCACGTT

SPHK2 Homo Sapiens SPHK2_Hs_For GCCCCGGTTGCTTCTATTG Homo Sapiens SPHK2_Hs_Rev GTTCTGTCTGGATGAGGTTGAAGG

SPHK2 Mus Musculus SPHK2_Mm_For CCACGTGGTGCCAATGATC Mus Musculus SPHK2 Mm Rev CAGCTCACGGGCATGGTT

Table 6: Ct values obtained during quantitative real time PCR: Total RNA isolated from human brain, human cerebral cortex, human hippocampus and mouse or rat primary hippocampal neuronal cultures is tested for the presence of the respective RNA via quantitative realtime PCR.

EXAMPLE 5: Amyloid Beta Peptide Reduction Via Knock Down of HIT Expression The effect of an antagonist can be mimicked through the use of siRNA-based strategies, which result in decreased expression levels of the targeted protein. Adenoviral mediated siRNA or knock down constructs based upon the sequences shown in Table 1, are constructed as described in WO03/020931. The loop sequence, 5' UUGCUAU-3' (SEQ ED NO: 142) is used to make a self-complementing siRNA. Adenoviral knock down constructs are used to transduce mouse, rat or human primary neuronal cells and/or cell lines (e.g. HEK293, SH-SY5Y, DvIR-32, SK-N-SH, SK-N-MC, H4, CHO, COS, HeLa) stably over-expressing APPwt or not. Human primary neurons are purchased from Cellial Technologies, France. Rat primary neuron cultures are prepared from brain of E18-E19-day-old fetal Sprague Dawley rats and mouse primary neuron cultures from E14 (cortical cultures) or E17 (cortical and hippocampal cultures)-day old fetal FVB mice, according to Goslin and Banker (Culturing Nerve cells, second edition, 1998 ISBN 0-262-02438-1). Single cell suspensions are prepared from hippocampus or cortical samples. The number of cells is determined (only taking into account the living cells) and cells are plated on poly-L-lysine-coated plastic 96-well plates in minimal essential medium (MEM) supplemented with 10% horse serum. The cells are seeded at a density between 30,000 and 60,000 cells per well (i.e. about 100,000 - 200,000 cells/cm², respectively). After 3-4 h, culture medium is replaced by 150 μl serum-free neurobasal medium with B27 supplement (GD3CO BRL). Cytosine arabinoside (5 μM) is added 24 h after plating to prevent non-neuronal (glial) cell proliferation. Neurons are used at day 5-7 after plating. Before adenoviral transduction, 150 μl conditioned medium of these cultures is transferred to the corresponding wells in an empty 96-well plate and 50 μl of the conditioned medium is returned to the cells. The remaining 100 μl/well is stored at 37°C and 5% CO₂. Both hippocampal and cortical primary neuron cultures are co-infected with the crude lysate of virus containing the cDNAs of the HIT polypeptides, and human wild type APP or human Swedish mutant APP, at different MOIs, ranging from 100 to 3000. Sixteen to twenty-four hours after transduction, virus is removed and cultures are washed with 100 μl pre-warmed fresh neurobasal medium. After removal of the wash solution, the remaining 100 μl of the stored conditioned medium is transferred to the corresponding cells. From this point on, cells secrete amyloid beta peptide into the conditioned medium and its concentration is deteirmined by amyloid beta 1-42 specific ELISAs (see EXAMPLE 1). Since rodent APP genes carry a number of mutations in APP compared to the human sequence, a detection antibody recognizing rodent amyloid beta is used (JRF/rAb/2; obtained from M Mercken, Johnson and Johnson Pharmaceutical Research and Development, B-2340 Beerse, Belgium). Alternatively, the human amyloid beta ELISAs (see EXAMPLE 1) is performed on cells co-transduction with human wild type APP or human Swedish mutant APP (which enhances amyloid-beta production) cDNA. The conditioned media are collected 24, 48 and 96 hours after exchanging viras-contøining medium by stored conditioned medium. Co-infection of SH-SY5Y cells with adenoviruses expressing APPwt and HIT KD sequences reduces amyloid beta 1-42 levels in the conditioned medium compared to GL2 KD virus infected cells. In addition, RNA is isolated from these infected cells and the HITS RNA levels are determined via real time PCR. Determination of the levels of household keeping genes allows the normalization of RNA levels of the target gene between different RNA samples, represented as delta Ct values. The RNA levels of HITS are reduced in cells infected with the HITS adenoviral KD virus; accordingly, the HITS are effective for the reduction of secreted amyloid beta peptide 1-42 levels.

EXAMPLE 6: Identification of small molecules that inhibit HIT protease activity. Compounds are screened for inhibition of the activity of the HIT polypeptides of the present invention. The affinity of the compounds to the HIT polypeptides is determined in an experiment detecting changes in levels of cleaved substrate. In brief, if the HIT polypeptide is a protease it is incubated with its substrate in an appropriate buffer. The combination of these components results in the cleavage of the substrate. The polypeptides can be applied as complete polypeptides or as polypeptide fragments, which still comprise the catalytic activity of the polypeptide of the invention. Cleavage of the substrate can be followed in several ways. In a first method, the substrate protein is heavily labeled with a fluorescent dye, like fluorescein, resulting in a complete quenching of the fluorescent signal. Cleavage of the substrate however, releases individual fragments, which contain less fluorescent labels. This results in the loss of quenching and the generation of a fluorescent signal, which correlates to the levels of cleaved substrate. Cleavage of the protein, which results in smaller peptide fragments, can also be measured using fluorescent polarization (FP). Alternatively, cleavage of the substrate can also be detected using fluorescence resonance energy transfer (FRET): a peptide substrate is labeled on both sides with either a quencher and fluorescent molecule, like DABCYL and ED ANS. Upon cleavage of the substrate both molecules are separated resulting in fluorescent signal correlating to the levels of cleaved substrate. In addition, cleavage of a peptide substrate can also generate a new substrate for another enzymatic reaction, which is then detected via a fluorescent, chemiluminescent or colorimetric method. Small molecules are randomly screened or are preselected based upon drug class, i.e. protease, or upon virtual ligand screening (VLS) results. VLS uses virtual docking technology to test large numbers of small molecules in sihco for their binding to the polypeptide of the invention. Small molecules are added to the proteolytic reaction and their effect on levels of cleaved substrate is measured with the described technologies. Small molecules that inhibit the protease activity are identified and are subsequently tested at different concentrations. IC50 values are calculated from these dose response curves. Strong binders have an IC50 in the nanomolar and even picomolar range. Compounds that have an IC50 of at least 10 micromol or better (nmol to pmol) are applied in amyloid beta secretion assay to check for their effect on the beta amyloid secretion and processing.

EXAMPLE 7: Identification Of Small Molecules That Inhibit HIT Kinase Activity Compounds are screened for inhibition of the activity of the HITS that are kinase polypeptides. The affinity of the compounds to the polypeptides is deteirmined in an experiment detecting changed reaction conditions after phosphorylation. The HIT kinase polypeptides are incubated with its substrate and ATP in an appropriate buffer. The combination of these components results in the in vitro phosphorylation of the substrate. Sources of compounds include commercially available screening library, peptides in a phage display library or an antibody fragment library, and compounds that have been demonstrated to have binding affinity for a HIT kinase. The HIT kinase polypeptides can be prepared in a number of ways depending on whether the assay will be run using cells, cell fractions or biochemically, on purified proteins. The polypeptides can be applied as complete polypeptides or as polypeptide fragments, which still comprise HIT kinase catalytic activity. Identification of small molecules inhibiting the activity of the HIT kinase polypeptides is performed by measuring changes in levels of phosphorylated substrate or

ATP. Since ATP is consumed during the phosphorylation of the substrate, its levels correlate with the kinase activity. Measuring ATP levels via chemiluminescent reactions therefore represents a method to measure kinase activity in vitro (Perldn Elmer). In a second type of assay, changes in the levels of phosphorylated substrate are detected with phosphospecific agents and are correlated to kinase activity. These levels are detected in solution or after irnmobilization of the substrate on a microtiter plate or other carrier. In solution, the phosphorylated substrate is detected via fluorescence resonance energy transfer (FRET) between the Eu labeled substrate and an APC labeled phosphospecific antibody (Perkin

Elmer), via fluorescence polarization (FP) after binding of a phosphospecific antibody to the fluorescently labeled phosphorylated substrate (Panvera), via an Amplified Luminescent

Proximity Homogeneous Assay (ALPHA) using the phosphorylated substrate and phosphospecific antibody, both coupled to ALPHA beads (Perkin Elmer) or using the IMAP binding reagent that specifically detects phosphate groups and thus alleviates the use of the phosphospecific antibody (Molecular Devices). Alternatively, the substrate is immobilized directly or by using biotin-streptavidin on a microtiter plate. After irnmobilization, the level of phosphorylated substrate is detected using a classical ELISA where b ding of the phosphospecific antibody is either monitored via an enzyme such as horseradish peroxidase (HRP) or alkaline phospahtase (AP) which are either directly coupled to the phosphospecific antibody or are coupled to a secondary antibody. Enzymatic activity correlates to phosphorylated substrate levels. Alternatively, binding of the Eu-labeled phosphospecific antibody to the immobilized phosphorylated substrate is determined via time resolved fluorescence energy (TRF) (Perkin Elmer). In addition, the substrate can be coated on FLASH plates (Perkin Elmer) and phosphorylation of the substrate is detected using ³³P labeled ATP or ¹²⁵I labeled phosphospecific antibody. Small molecules are randomly screened or are preselected based upon drug class, (i.e. known kinase inhibitors), or upon virtual ligand screening (VLS) results. VLS uses virtual docking technology to test large numbers of small molecules in sihco for their binding to the polypeptide of the invention. Small molecules are added to the kinase reaction and their effect on levels of phosphorylated substrate is measured with one or more of the above- described technologies. Small molecules that inhibit the kinase activity are identified and are subsequently tested at different concentrations. IC₅0 values are calculated from these dose response curves.

Strong binders have an IC₅₀ in the nanomolar and even picomolar range. Compounds that have an IC50 of at least 10 micromol or better (nmol to pmol) are applied in amyloid beta secretion assay to check for their effect on the beta amyloid secretion and processing.

EXAMPLE 10: Ligand Screens For HIT GPCRs. Reporter Gene Screen. Mammalian cells such as Hek293 or CHO-K1 cells are either stably transfected with a plasmid harboring the luciferase gene under the control of a cAMP dependent promoter

(CRE elements) or transduced with an adenovirus harboring a luciferase gene under the control of a cAMP dependent promoter. In addition reporter constructs can be used with the luciferase gene under the control of a Ca²⁺ dependent promoter (NF-AT elements) or a promoter that is controlled by activated NF-κB. These cells, expressing the reporter construct, are then transduced with an adenovirus harboring the cDNA of a HIT GPCR. Forty (40) hours after transduction the cells are treated with the following: a) an agonist for the receptor and screened against a large collection of reference compounds comprising peptides (LOPAP, Sigma Aldrich), lipids (Biomol, TimTech), carbohydrates (Specs), natural compounds (Specs, TimTech), small chemical compounds (Tocris), commercially available screening libraries, and compounds that have been demonstrated to have binding affinity for a polypeptide comprising an amino acid sequence selected from the group consisting of the SEQ ID NOs of the HIT GPCRs; or b) a large collection of reference compounds comprising peptides (LOPAP, Sigma Aldrich), lipids (Biomol, TimTech), carbohydrates (Specs), natural compounds (Specs,

TimTech), small chemical compounds (Tocris), commercially available screening libraries, and compounds that have been demonstrated to have binding affinity for a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NOs of the HIT GPCRs. Compounds, which decrease the agonist induced increase in luciferase activity or the constitutive activity, are considered to be antagonists or inverse agonists for a HIT GPCR. These compounds are screened again for verification and screened against their effect on secreted amyloid beta peptide levels. The compounds are also screened to verify binding to the GPCR. The binding, amyloid-beta peptide and reporter activity assays can be performed in essentially any order to screen compounds. In addition, cells expressing the NF-AT reporter gene can be transduced with an adenovirus harboring the cDNA encoding the α-subunit of Gis or chimerical Gα subunits.

G₁5 is a promiscuous G protein of the G_q class that couples to many different GPCRs and as such re-directs their signaling towards the release of intracellular Ca²⁺ stores. The chimerical G alpha subunits are members of the G_s and Gj_/0 family by which the last 5 C-terminal residues are replaced by those of Gαq, these chimerical G-proteins also redirect cAMP signaling to Ca²⁺ signaling.

FLEPR screen. Mammalian cells such as Hek293 or CHO-K1 cells are stably transfected with an expression plasmid construct harboring the cDNA of a HIT GPCR. Cells are seeded, grown, and selected until sufficient stable cells can be obtained. Cells are loaded with a Ca²⁺ dependent fluorophore such as Fura3 or Fura4. After washing away the excess of fluorophore the cells are screened against a large collection of reference compounds comprising peptides (LOPAP, Sigma Aldrich), lipids (Biomol, TimTech), carbohydrates (Specs), natural compounds (Specs, TimTech), small chemical compounds (Tocris), commercially available screening libraries, and compounds that have been demonstrated to have binding affinity for a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NOs of the HIT GPCRs, by simultaneously adding an agonist (alternatively no agonist need be added if the constitutive activity of the receptor is used) and a compound to the cells. Activation of the receptor is measured as an almost instantaneously increase in fluorescence due to the interaction of the fluorophore and the Ca²⁺ that is released. Compounds that reduce or inhibit the agonist induced increase in fluorescence (or constitutive fluorescence) are considered to be antagonists or inverse agonists for the receptor they are screened against. These compounds are screened again to measure the amount of secreted amyloid beta peptide as well as binding to a HIT GPCR. AequoScreen. CHO cells, stably expressing Apoaequorin are stably transfected with a plasmid construct harboring the cDNA of a HIT GPCR. Cells are seeded, grown, and selected until sufficient stable cells can be obtained. The cells are loaded with coelenterazine, a cofactor for apoaequorin. Upon receptor activation intracellular Ca²⁺ stores are emptied and the aequorin will react with the coelenterazine in a light emitting process. The emitted light is a measure for receptor activation. The CHO, stable expressing both the apoaequorin and the receptor are screened against a large collection of reference compounds comprising peptides (LOPAP, Sigma Aldrich), lipids (Biomol, TimTech), carbohydrates (Specs), natural compounds (Specs, TimTech), small chemical compounds (Tocris), commercially available screening libraries, and compounds that have been demonstrated to have binding affinity for a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ED NOs of the HIT GPCRs, by simultaneously adding an agonist (alternatively no agonist need be added if the constitutive activity of the receptor is used) and a compound to the cells. Activation of the receptor is measured as an almost instantaneously light flash due to the interaction of the apoaequorin, coelenterazine, and the Ca²⁺ that is released. Compounds that reduce or inhibit the agonist induced increase in light or the constitutive activity are considered to be antagonists or inverse agonists for the receptor they are screened against. These compounds are screened again to measure the amount of secreted amyloid beta peptide as well as binding to a HIT GPCR. In addition, CHO cells stable expressing the apoaequorin gene are stably transfected with a plasmid construct harboring the cDNA encoding the α-subunit of G₁₅ or chimerical G_α subunits. G₁₅ is a promiscuous G protein of the G_q class that couples to many different GPCRs and as such redirects their signaling towards the release of intracellular Ca²⁺ stores. The chimerical G alpha subunits are members of the G_s and Gy₀ family by which the last 5 C- terminal residues are replaced by those of Gα_q, these chimerical G-proteins also redirect cAMP signaling to Ca²⁺ signaling. Screening for compounds that bind to the GPCR polypeptides (displacement experiment Compounds are screened for binding to the HIT GPCR polypeptides. The affinity of the compounds to the polypeptides is determined in a displacement experiment. In brief, the GPCR polypeptides are incubated with a labeled (radiolabeled, fluorescent labeled) ligand that is known to bind to the polypeptide and with an unlabeled compound. The displacement of the labeled ligand from the polypeptide is determined by measuring the amount of labeled ligand that is still associated with the polypeptide. The amount associated with the polypeptide is plotted against the concentration of the compound to calculate IC50 values. This value reflects the binding affinity of the compound to its target, i.e. the HIT GPCR polypeptides. Strong binders have an IC₅0 in the nanomolar and even picomolar range. Compounds that have an IC5₀ of at least 10 micromol or better (nmol to pmol) are applied in beta amyloid secretion assay to check for their effect on the beta amyloid secretion and processing. The HIT GPCR polypeptides can be prepared in a number of ways depending on whether the assay are run on cells, cell fractions or biochemically, on purified proteins.

Screening for compounds that bind to a HIT GPCR (generic GPCR screening assay) When a G protein receptor becomes constitutively active, it binds to a G protein (G_q,

G_s, Gj, Go) and stimulates the binding of GTP to the G protein. The G protein then acts as a GTPase and slowly hydrolyses the GTP to GDP, whereby the receptor, under normal conditions, becomes deactivated. However, constitutively activated receptors continue to exchange GDP to GTP. A non-hydrolyzable analog of GTP, [³⁵S]GTPγS, can be used to monitor enhanced binding to membranes which express constitutively activated receptors. It is reported that [³⁵S]GTPγS can be used to monitor G protein coupling to membranes in the absence and presence of ligand. Moreover, a preferred approach is the use of a GPCR-G protein fusion protein. The strategy to generate a HIT GPCR-G protein fusion protein is well known for those known in the art. Membranes expressing HIT GPCR-G protein fusion protein are prepared for use in the direct identification of candidate compounds such as inverse agonist. Homogenized membranes with HIT GPCR-G protein fusion protein are transferred in a 96-well plate. A pin-tool is used to transfer a candidate compound in each well plus [³⁵S]GTPγS, followed by incubation on a shaker for 60 minutes at room temperature. The assay is stopped by spinning of the plates at 4000 RPM for 15 minutes at 22°C. The plates are then aspirated and radioactivity is then read.

Receptor Ligand Binding Study On Cell Surface The receptor is expressed in mammalian cells (Hek293, CHO, COS7) by adenoviral transducing the cells (see US 6,340,595). The cells are incubated with both labeled ligand (iodinated, tritiated, or fluorescent) and the unlabeled compound at various concentrations, ranging from 10 pM to 10 μM (3 hours at 4°C: 25 mM HEPES, 140 mM NaCl, 1 mM CaCl₂, 5 mM MgCl₂ and 0.2% BSA, adjusted to pH 7.4). Reactions mixtures are aspirated onto PEI- treated GF/B glass filters using a cell harvester (Packard). The filters are washed twice with ice cold wash buffer (25 mM HEPES, 500 mM NaCl, 1 mM CaCl₂, 5 mM MgCl₂, adjusted to pH 7.4). Scintillant (MicroScint-10; 35 μl) is added to dried filters and the filters counted in a (Packard Topcount) scintillation counter. Data are analyzed and plotted using Prism software (GraphPad Software, San Diego, Calif.). Competition curves are analyzed and IC50 values calculated. If one or more data points do not fall within the sigmoidal range of the competition curve or close to the sigmoidal range the assay is repeated and concentrations of labeled ligand and unlabeled compound adapted to have more data points close to or in the sigmoidal range of the curve. Receptor Ligand Binding Studies On Membrane Preparations Membranes preparations are isolated from mammalian cells (Hek293, CHO, COS7) cells over expressing the receptor is done as follows: Medium is aspirated from the transduced cells and cells are harvested in 1 x PBS by gentle scraping. Cells are pelleted (2500 rpm 5 min) and resuspended in 50 mM Tris pH 7.4 (10 x 10⁶ cells/ml). The cell pellet is homogenized by sonicating 3 x 5 sec (UP50H; sonotrode MSI; max amplitude: 140 μm; max Sonic Power Density: 125W/cm²). Membrane fractions are prepared by centrifuging 20 min at maximal speed (13000 rpm ~15000 to 20000g or rcf). The resulting pellet is resuspended in 500 μl 50 mM Tris pH 7.4 and sonicated again for 3 x 5 sec. The membrane fraction is isolated by centrifugation and finally resuspended in PBS. Binding competition and derivation of IC50 values are determined as described above.

Intemalization screen (1) Activation of a GPCR-associated signal transduction pathway commonly leads to translocation of specific signal transduction molecules from the cytoplasm to the plasma membrane or from the cytoplasm to the nucleus. Norak has developed their transfluor assay based on agonist-induced translocation of receptor-β-arrestin-GFP complex from the cytosol to the plasma membrane and subsequent intemalization of this complex, which occurs during receptor desensitization. A similar assay uses GFP tagged receptor instead of β-arrestin. Hek293 cells are transduced with a HIT GPCR vector that translates for a HIT GPCR-eGFP fusion protein. 48 hours after transduction, the cells are set to fresh serum-free medium for 60 minutes and treated with a ligand for 15, 30, 60 or 120 minutes at 37°C and 5% CO₂. After indicated exposure times, cells are washed with PBS and fixed with 5% paraformaldehyde for 20 minutes at RT. GFP fluorescence is visualized with a Zeiss microscope with a digital camera. This method aims for the identification of compounds that inhibit a ligand-mediated (constitutive activity-mediated) translocation of the fusion protein to intracellular compartments.

Intemalization screen (2) Various variations on translocation assays exists using β-arrestin and β-galactosidase enzyme complementation and BRET based assays with receptor as energy donor and β- arrestin as energy acceptor. Also the use of specific receptor antibodies labeled with pH sensitive dyes are used to detect agonist induced receptor translocation to acidic lysosomes. All of the translocation assays are used for screening for both agonistic and antagonistic acting ligands. Melanophore assay (Arena Pharmaceutical^') The melanophore assay is based on the ability of GPCRs to alter the distribution of melanin containing melanosomes in Xenopus melanophores. The distribution of the melanosomes depends on the exogenous receptor that is either Gi/₀ or G_s/_q coupled. The distribution of the melanosomes (dispersed or aggregated) is easily detected by measuring light absorption. This type of assay is used for both agonist as well as antagonist compound screens.

Claims

We claim:

1. A method for identifying a compound that inhibits the processing of amyloid-beta precursor protein in a mammalian cell, comprising (a) contacting a compound with a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732, 801-937; and (b) measuring a compound-polypeptide property related to the production of amyloid-beta peptide. 2. The method according to claim 1, wherein said polypeptide is in an In vitro cell-free preparation.

3. The method according to claim 2, wherein said polypeptide is present in a mammalian cell .

4. The method of claim 1, wherein said property is a binding affinity of said compound to said polypeptide.

5. The method of claim 3, wherein said property is activation of a biological pathway producing an indicator of the processing of amyloid-beta precursor protein.

6. The method of claim 5 wherein said indicator is amyloid-beta peptide.

7. The method of claim 6 wherein said amyloid-beta peptide is selected from the group consisting of one or more of amyloid-beta peptide 1-42, 1-40, 11-42 and 11-40.

8. The method of claim 7 wherein said amyloid-beta peptide is amyloid-beta peptide 1-42.

9. The method according to claim 2, wherein said compound is a peptide in a phage display library or an antibody fragment library.

10. An agent for the inhibition of amyloid-beta precursor processing selected from the group consisting of an antisense polynucleotide, a ribozyme, and a ^• small interfering RNA (siRNA) , wherein said agent comprises a nucleic acid sequence complementary to, or engineered from, a naturally-occurring polynucleotide sequence encoding a polypeptide comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 501-732.

12. The agent according to claim 10, wherein a vector in a mammalian cell expresses said agent.

13. The agent according to claim 11, wherein said vector is an adenoviral, retroviral, adeno-associated viral, lentiviral, a herpes simplex viral or a sendaiviral vector.

14. The agent according to claim 12, wherein said antisense polynucleotide and said siRNA comprise an antisense strand of 17-25 nucleotides complementary to a sense strand, wherein said sense strand is selected from 17-25 continuous nucleotides of a nucleic acid sequence selected from the group consisting of SEQ ID NO: 201-432.

15. The agent according to claim 14, wherein said siRNA further comprises said sense strand.

16. The agent according to claim 15, wherein said sense strand is selected from the group consisting of SEQ ID NO: 1-141.

17. The agent according to claim 16, wherein said siRNA further comprises a loop region connecting said sense and said antisense strand.

18. The agent according to claim 17 wherein said loop region comprises a nucleic acid sequence defined of SEQ ID NO: 142. 19. The agent according to claim 10, wherein said agent is an antisense polynucleotide, ribozyme, or siRNA comprising a nucleic acid sequence complementary to from 17-25 continuous nucleotides of a nucleic acid sequence selected from the group consisting of SEQ ID NO: 201-432.

20. A cognitive enhancing pharmaceutical composition comprising a therapeutically effective amount of an agent of claim 10 in admixture with a pharmaceutically acceptable carrier.

21. The cognitive enhancing pharmaceutical composition according to claim 20 wherein said agent comprises a polynucleotide comprising a nucleic acid sequence from 17-

25 continuous nucleotides selected from the group consisting of SEQ ID NO: 201-432, a polynucleotide complementary to said nucleic acid sequence, and a combination thereof. 22. A method of inhibiting the processing of amyloid-beta precursor protein in a subject suffering or susceptible to the abnormal processing of said protein, comprising administering to said subject a pharmaceuticall^y composition according to claim 21. 23. A method according to claim 22 for treatment or prevention of a condition involving cognitive impairment or a susceptibility to the condition.

24. The method according to claim 23 wherein the condition is Alzheimer's disease. 25. A pharmaceutical composition for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to the condition, comprising an effective amyloid-beta precursor processing-inhibiting amount of a HIT inhibitor. 26. A composition according to claim 25, wherein said HIT inhibitor is selected from the group consisting of the 1,2,3, 9-tetrahydro-3-imidazol-l-ylmethyl-4H-carbazol-4- ones and the indazolyl carboxylic acid amides, and pharmaceutically acceptable salts, hydrates, solvates, or prodrugs thereof in admixture with a pharmaceutically acceptable carrier.

27. A pharmaceutical composition according to claim 20, further comprising labeling indicating use of said composition for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to said condition.

28. A pharmaceutical composition according to claim 25, further comprising labeling indicating use of said composition for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to said condition.

29. Use of a cognitive enhancing pharmaceutical composition according to claims 20 or 21 in the manufacture of _sa medicament for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to the condition.

30. Use of a pharmaceutical composition according to any of the claims 25-28 in the manufacture of a medicament for the treatment or prevention of a condition involving cognitive impairment or a susceptibility to said condition.

31. Use according to claim 29 or 30, wherein the condition is Alzheimer's disease.