WO2006010531A1 - Prohormone convertase 1 utilisee en tant que marqueur/cible pour la defaillance des cellules beta - Google Patents

Prohormone convertase 1 utilisee en tant que marqueur/cible pour la defaillance des cellules beta Download PDF

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WO2006010531A1
WO2006010531A1 PCT/EP2005/007855 EP2005007855W WO2006010531A1 WO 2006010531 A1 WO2006010531 A1 WO 2006010531A1 EP 2005007855 W EP2005007855 W EP 2005007855W WO 2006010531 A1 WO2006010531 A1 WO 2006010531A1
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pcl
beta
protein
cell failure
compound
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PCT/EP2005/007855
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English (en)
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Andreas Christ
Stefan Evers
Kurt Krapfenbauer
Elena Sebokova
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F. Hoffmann-La Roche Ag
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/34—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase
    • C12Q1/37—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase involving peptidase or proteinase
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/573—Immunoassay; Biospecific binding assay; Materials therefor for enzymes or isoenzymes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
    • G01N2333/90—Enzymes; Proenzymes
    • G01N2333/914—Hydrolases (3)
    • G01N2333/948—Hydrolases (3) acting on peptide bonds (3.4)
    • G01N2333/95—Proteinases, i.e. endopeptidases (3.4.21-3.4.99)
    • G01N2333/964—Proteinases, i.e. endopeptidases (3.4.21-3.4.99) derived from animal tissue
    • G01N2333/96425—Proteinases, i.e. endopeptidases (3.4.21-3.4.99) derived from animal tissue from mammals
    • G01N2333/96427—Proteinases, i.e. endopeptidases (3.4.21-3.4.99) derived from animal tissue from mammals in general
    • G01N2333/9643—Proteinases, i.e. endopeptidases (3.4.21-3.4.99) derived from animal tissue from mammals in general with EC number
    • G01N2333/96433—Serine endopeptidases (3.4.21)
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2500/00—Screening for compounds of potential therapeutic value
    • G01N2500/04—Screening involving studying the effect of compounds C directly on molecule A (e.g. C are potential ligands for a receptor A, or potential substrates for an enzyme A)
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2800/00—Detection or diagnosis of diseases
    • G01N2800/52—Predicting or monitoring the response to treatment, e.g. for selection of therapy based on assay results in personalised medicine; Prognosis

Definitions

  • Type 2 diabetes is a disease of fast growing worldwide importance and can be described as a failure of the pancreatic beta-cell (beta-cell failure) to compensate, with enhanced insulin secretion of the beta-cells, for peripheral insulin resistance.
  • This failure is explained by both a relative loss of beta-cell mass as well as secretory defects that include enhanced basal insulin secretion by the beta-cells and a selective loss of sensitivity to insulin mainly in skeletal muscle but also in other organs.
  • the loss of beta-cell function is believed to be triggered by long-term exposure to enhanced levels of glucose and lipids (glyco- and lipotoxicity).
  • beta-cell failure There is currently no clinically proven treatment that could prevent or delay beta- cell failure under lipo/glycotox conditions. It would also be useful to identify better targets for treatment and markers for detection of beta-cell failure or function that are more sensitive or more reliable than the markers commonly used, such as insulin, proinsulin or C-peptide.
  • the aim of the present invention is to identify and provide a novel target to screen for compounds that prevent, attenuate, or inhibit beta-cell failure, and for a marker that allows for monitoring and/or diagnosis of beta-cell failure at an earlier stage of type II diabetes and more reliably than can presently be done.
  • PCl Prohormone convertase PCl (also PC3) is an enzyme active in the secretory pathway which has been implicated in the processing of a number of polypeptides, including pro-islet amyloid polypeptide and proinsulin.
  • PCl polymorphisms and NIDDM (Kalidas et al, 1998, Diabetes 47, 287-289).
  • the present invention provides a target for the treatment and/ or prevention of beta-cell failure, and a novel marker for the early diagnosis of beta- cell failure in diabetes.
  • novel target and/or marker PCl maybe used for diagnostic, monitoring as well as for screening purposes.
  • the diagnostic method according to the present invention may help to assess efficacy of treatment and recurrence of beta-cell failure in the follow-up of patients. Therefore, the present invention provides the use of protein PCl for monitoring the efficacy of treatment of diabetes.
  • the diagnostic method according to the present invention is used for patient screening purposes. I.e., it is used to assess subjects without a prior diagnosis of diabetes by measuring the level of PCl and correlating the level of PCl to the presence or absence of beta-cell failure.
  • the methods of the present invention are useful for monitoring progression of the disease through the different stages leading to diabetes, namely Insulin Resistance, Impaired Glucose Tolerance and Diabetes.
  • the present invention thus provides a method for monitoring the progression of diabetes, comprising the steps of (a) providing a liquid sample obtained from an individual, (b) contacting said sample with a specific binding agent for PCl under conditions appropriate for formation of a complex between said binding agent and PCl, and (c) correlating the amount of complex formed in (b) to the amount of complex formed in beta-cell failure.
  • the present invention also provides a method for monitoring the efficacy of treatment of diabetes, comprising the steps of (a) providing a liquid sample obtained from a patient treated against diabetes, (b) contacting said sample with a specific binding agent for PCl under conditions appropriate for formation of a complex between said binding agent and PCl, and (c) correlating the amount of complex formed in (b) to the amount of complex formed in the absence of treatment.
  • the present invention provides a method of screening for a compound which interacts with PCl, comprising the steps of a) contacting protein PCl with a compound or a plurality of compounds under compositions which allow interaction of said compound or a plurality of compounds with PCl; and b) detecting the interaction between said compound or plurality of compounds with said polypeptide.
  • the present invention provides a method of screening for a compound that prevents and/or inhibits and/or attenuates beta-cell failure, comprising the steps of a) contacting a compound with protein PCl; and b) measuring the activity of protein PCl; wherein a compound which stimulates or inhibits the activity of protein PCl is a compound that may prevent and/or inhibit and/ or attenuate beta-cell failure.
  • said method additionally comprises the step of immobilizing protein PCl prior to step a) or between steps a) and b).
  • activity refers to the enzymatic activity of PCl.
  • Assays to measure the enzymatic activity of PCl are well known in the art and have been described e.g. in: Higham et al., Eur. J. Biochem. 267, 4998-5004; Qian et al., JBC 275, 2000, 23596-23601; Dey et al., 2004, Endocrinology 145, 1961-71; Peinado et al, J. Neurochem. 2003, 87, 868-878.
  • the present invention also includes cell-free assays.
  • assays involve contacting a form of PCl (e.g., full-length polypeptide, a biologically active fragment of said polypeptide, or a fusion protein comprising all or a portion of said polypeptide) with a test compound and determining the ability of the test compound to bind to said polypeptide. Binding of the test compound to said polypeptide can be determined either directly or indirectly as described above.
  • the assay includes contacting the said polypeptide with a known compound which binds said polypeptide to form an assay mixture, contacting the assay mixture with a test compound, and determining the ability of the test compound to interact with said polypeptide, wherein determining the ability of the test compound to interact with said polypeptide comprises determining the ability of the test compound to preferentially bind to the said polypeptide as compared to the known compound.
  • the cell-free assays of the present invention are amenable to use of either a membrane-bound form of a polypeptide or a soluble fragment thereof.
  • solubilizing agent such that the membrane-bound form of the polypeptide is maintained in solution.
  • solubilizing agents include non- ionic detergents such as n-octylglucoside, n-dodecylglucoside, n-dodecylmaltoside, octanoyl-N-methylglucamide, decanoyl-N-methylglucamide, Triton X-IOO, Triton X- 114, Thesit, Isotridecypoly( ethylene glycol ether)n, 3-[(3- cholamidopropyl)dimethylamminio]-l -propane sulfonate (CHAPS), 3-[(3- cholamidopropyl)dimethylamminio] -2-hydroxy- 1-propane sulfonate (CHAP
  • binding of a test compound to a polypeptide, or interaction of a polypeptide with a binding molecule in the presence and absence of a candidate compound can be accomplished in any vessel suitable for containing the reactants. Examples of such vessels include microtitre plates, test tubes, and micro- centrifuge tubes.
  • a fusion protein can be provided which adds a domain that allows one or both of the proteins to be bound to a matrix.
  • glutathione-S-transferase fusion proteins can be adsorbed onto glutathione sepharose beads (Sigma Chemical; St. Louis, Mo.) or glutathione derivatized microtitre plates, which are then combined with the test compound or the test compound and either the non-adsorbed binding protein or polypeptide, and the mixture incubated under conditions conducive to complex formation (e.g., at physiological conditions for salt and pH). Following incubation, the beads or microtitre plate wells are washed to remove any unbound components and complex formation is measured either directly or indirectly, for example, as described above.
  • the complexes can be dissociated from the matrix, and the level of binding or activity of a polypeptide hereinbefore described can be determined using standard techniques.
  • a polypeptide hereinbefore described or its binding molecule can be immobilized utilizing conjugation of biotin and streptavidin.
  • Biotinylated polypeptide of the invention or target molecules can be prepared from biotin-NHS (N-hydroxy-succinimide) using techniques well known in the art (e.g., biotinylation kit, Pierce Chemicals; Rockford, 111.), and immobilized in the wells of streptavidin- coated 96 well plates (Pierce Chemical).
  • antibodies reactive with a polypeptide or binding molecules can be derivatized to the wells of the plate. Unbound binding protein or polypeptide of the invention are trapped in the wells by antibody conjugation.
  • Methods for detecting such complexes include immunodetection of complexes using antibodies reactive with a polypeptide hereinbefore described or binding molecule, as well as enzyme-linked assays which rely on detecting an enzymatic activity associated with a polypeptide or binding molecule.
  • the present invention also provides a method of screening for a compound that prevents and/or inhibits and/ or delays beta-cell failure, comprising the step of detecting soluble PCl secreted from a host in the presence or absence of said compound, wherein a compound that prevents and/or inhibits and/or delays beta-cell failure is a compound with which the level of PCl secreted by a host is changed.
  • a host may be a model cell representing beta-cells in culture, or an animal which can be used as a model for beta cell failure.
  • the present invention also provides for a use of protein PCl as a target and/or as a marker for screening for a compound that prevents and/or inhibits beta-cell failure.
  • the diagnostic method according to the present invention is based on a liquid sample which is derived from an individual. Unlike to methods known from the art PCl is specifically measured from this liquid sample by use of a specific binding agent.
  • a specific binding agent is, e.g., a receptor for PCl or an antibody to PCl.
  • a receptor for PCl or an antibody to PCl.
  • specific is used to indicate that other biomolecules present in the sample do not significantly bind to the binding agent specific for PCl. A level of less than 5% cross-reactivity is considered not significant.
  • a specific binding agent preferably is an antibody reactive with PCl.
  • the term antibody refers to a polyclonal antibody, a monoclonal antibody, fragments of such antibodies, as well as to genetic constructs comprising the binding domain of an antibody.
  • Antibodies are generated by state of the art procedures, e.g., as described in Tijssen (Tijssen, P., Practice and theory of enzyme immunoassays 11 (1990) the whole book, especially pages 43-78; Elsevier, Amsterdam).
  • polyclonal antibodies raised in rabbits have been used.
  • polyclonal antibodies from different species e.g. rats or guinea pigs, as well as monoclonal antibodies can also be used. Since monoclonal antibodies can be produced in any amount required with constant properties, they represent ideal tools in development of an assay for clinical routine.
  • the generation and use of monoclonal antibodies to PCl in a method according to the present invention is yet another preferred embodiment.
  • PCl has been identified as a marker which is useful in the diagnosis of beta-cell failure
  • alternative ways maybe used to reach a result comparable to the achievements of the present invention.
  • alternative strategies to generate antibodies maybe used.
  • Such strategies comprise amongst others the use of synthetic peptides, representing an epitope of PCl for immunization.
  • DNA immunization also known as DNA vaccination may be used.
  • the liquid sample obtained from an individual is contacted with the specific binding agent for PCl under conditions appropriate for formation of a binding agent PCl -complex.
  • Such conditions need not be specified, since the skilled artisan without any inventive effort can easily identify such appropriate incubation conditions.
  • the amount of complex is measured and correlated to the diagnosis of beta-cell failure.
  • the skilled artisan will appreciate there are numerous methods to measure the amount of the specific binding agent PCl-complex all described in detail in relevant textbooks (cf., e.g., Tijssen P., supra, or Diamandis, et al., eds. (1996) Immunoassay, Academic Press, Boston).
  • PCl is detected in a sandwich type assay format.
  • a first specific binding agent is used to capture PCl on the one side and a second specific binding agent, which is labeled to be directly or indirectly detectable, is used on the other side.
  • PCl is measured in the liquid sample by determining the activity of PCl in said liquid sample. The activity of PCl in the liquid sample is then correlated to the activity of PCl in beta-cell failure, when monitoring the progression of diabetes, or to the activity of PCl in the absence of treatment, when monitoring the efficacy of treatment, or it is correlated to the diagnosis of beta-cell failure.
  • the activity of PCl is determined using the complex of PCl with a binding agent which is formed as hereinbefore described.
  • PCl can be measured from a liquid sample obtained from an individual sample. No tissue and no biopsy sample is required to apply the marker PCl in the diagnosis of beta-cell failure.
  • the method according to the present invention is practiced with serum as liquid sample material.
  • the method according to the present invention is practiced with plasma as liquid sample material.
  • the method according to the present invention is practiced with whole blood as liquid sample material.
  • Antibodies to PCl with great advantage can be used in established procedures, e.g., to beta-cell failure in situ, in biopsies, or in immunohistological procedures.
  • an antibody to PCl is used in a qualitative (PCl present or absent) or quantitative (PCl amount is determined) immunoassay.
  • the present invention relates to use of protein PCl as a marker molecule in the diagnosis of beta-cell failure from a liquid sample obtained from an individual.
  • marker molecule is used to indicate that changes in the level of the analyte PCl as measured from a bodily fluid of an individual marks the presence of beta- cell failure.
  • novel marker PCl in the monitoring of disease progression in diabetes.
  • the use of protein PCl itself represents a significant progress to the challenging field of beta-cell failure diagnosis. Combining measurements of PCl with other known markers for diabetes, like insulin, or with other markers of beta-cell failure yet to be discovered, leads to further improvements. Therefore in a further preferred embodiment the present invention relates to the use of PCl as a marker molecule for diabetes, preferably for beta-cell failure, in combination with another marker molecule for diabetes, preferably for beta-cell failure, in the diagnosis of diabetes, preferably of beta- cell failure from a liquid sample obtained from an individual.
  • Preferred selected other diabetes markers with which the measurement of beta-cell failure may be combined are insulin, pre-insulin, and/or C-peptide.
  • Diagnostic reagents in the field of specific binding assays like immunoassays, usually are best provided in the form of a kit, which comprises the specific binding agent and the auxiliary reagents required to perform the assay.
  • the present invention therefore also relates to an immunological kit comprising at least one specific binding agent for PCl and auxiliary reagents for measurement of PCl.
  • One way of assessing clinical utility of the novel marker PCl is by measuring its levels in 10 diabetic patients depending on injections of exogenous insulin and comparing the levels with those measured in 10 patients with demonstrated normal beta-cell function. For statistical analysis, Standard Student's t-test evaluation is performed with values ⁇ 0.05 being taken as significant.
  • ROC receiver-operating characteristics
  • the clinical performance of a laboratory test depends on its diagnostic accuracy, or the ability to correctly classify subjects into clinically relevant subgroups. Diagnostic accuracy measures the test's ability to correctly distinguish two different conditions of the subjects investigated. Such conditions are for example health and disease.
  • the ROC plot depicts the overlap between the two distributions by plotting the sensitivity versus 1 - specificity for the complete range of decision thresholds.
  • sensitivity or the true-positive fraction [defined as (number of true- positive test results) (number of true-positive + number of false-negative test results)]. This has also been referred to as positivity in the presence of a disease or condition. It is calculated solely from the affected subgroup.
  • false-positive fraction or 1 - specificity [defined as (number of false-positive results)/ (number of true-negative + number of false-positive results)]. It is an index of specificity and is calculated entirely from the unaffected subgroup.
  • the ROC plot is independent of the prevalence of disease in the sample.
  • Each point on the ROC plot represents a sensitivity/-specificity pair corresponding to a particular decision threshold.
  • a test with perfect discrimination has an ROC plot that passes through the upper left corner, where the true- positive fraction is 1.0, or 100% (perfect sensitivity), and the false-positive fraction is 0 (perfect specificity).
  • the theoretical plot for a test with no discrimination is a 45° diagonal line from the lower left corner to the upper right corner. Most plots fall in between these two extremes.
  • UFV4BGC25 UFV4BGC25
  • 2.0 mg were applied on immobilised pH 3- 10 non linear gradient strips (Amersham, Pharmacia Biotechnology, Uppsala, Sweden) at both the basic and acid ends of the strips.
  • the proteins were focused at 200 V after which the voltage is gradually increasing to 5000 V with 2 V/min. Focusing was continued at 5000 V for 24 h.
  • the second-dimensional separation was performed on a 12% polyacrylamide gel (Biosolve, Walkinswaard, Netherland). The gels (18O x 200 x 1.5 mm) were run at 50 mA /gels, in an Ettan DALT II system (Amersham, Pharmacia Biotechnology, Uppsala, Sweden) accommodating twelve gels.
  • MALDI-MS MS analysis was performed as described (Langen, H., Roeder, D., Juranville, J.-F., Fountoulakis, M., Electrophoresis 1997, 18, 2085-2090) with minor modifications. Briefly, spots were excised, destained with 30% (v/v) acetonitrile in 0.1 M ammonium bicarbonate and dried in a Speed vac evaporator. The dried gel pieces were reswollen with 5 ⁇ l of 5 mM ammonium bicarbonate, (pH 8.8) containing 50 ng trypsin (Promega, Madison, WI, USA) were added, centrifuged for 1 min and left at room temperature for about 12 h.
  • Des-Arg-1 Bradykinin (Sigma) and ACTH (18-38) (Sigma) were used as standard peptides. Calibration was internal to the samples. The peptide masses were matched with the theoretical peptide masses of all proteins from all species of the SWISS- Prot database.
  • Mass spectrometric data is two times filtered using a low-pass median parametric spline filter in order to determine the instrument baseline.
  • the smoothed residual mean standard deviation from the baseline is used as an estimate of the instrument noise level in the data.
  • the data point with the largest deviation from the baseline is used to seed a non-linear (Levenberg-Marquardt) data fitting procedure to detect possible peptide peaks.
  • the fit procedure attempts to produce the best fitting average theoretical peptide isotope distribution parameterized by peak height, resolution, and monoisotopic mass. The convergence to a significant fit is determined in the usual way by tracking sigma values.
  • an estimate for the errors of the determined parameters is produced using a bootstrap procedure using sixteen repeats with a random exchange of 1/3 of the data points.
  • the resulting fit is subtracted from the data, the noise level in the vicinity of the fit is adjusted to the sum of the extrapolated noise level and the deviation from the peak fit, and the process is iterated to find the next peak as long as a candidate peak more than five times over level of noise can be found.
  • the process is stopped when more than 50 data peaks have been found.
  • the zero and first order of the time-of-flight to mass conversion are corrected using linear extrapolation from detected internal standard peaks, and confidence intervals for the monoisotopic mass values are estimated form the mass accuracies of the peaks and standards.
  • Probabilistic matching of spectra peaks to in-silico protein digests Peak mass lists for mass spectra are directly compared to theoretical digests for whole protein sequence databases. For each theoretical digest, [1-Tl(I- N P(pi))] cMatches is calculated, where N is the number of peptides in the theoretical digest, P(pi) is the number of peptides that match the confidence interval for the monoisotopic mass of the peak divided by the count of all peptides in the sequence database, and cMatches is the number of matches between digest and mass spectrum. It can be shown that this value is proportional to the probability of obtaining a false positive match between digest and spectrum. Probability values are further filtered for high significance of the spectra peaks that produce the matches.
  • Heparin Sepharose columns Based on the observation that most of the proteins with a signal function are glycosylated, the nature of Heparin Sepharose columns makes it a very versatile tool for the separation of many glycosylated proteins like e.g. proteins with signal function, growth factors, coagulation proteins and steroid receptors.
  • the ligand in the Heparin Sepharose column is a naturally occurring sulfated glycosaminglycan which is extracted from native proteoglycan of porcine intestinal mucosa. Heparin consists of alternating units of uronic acid and D-glucosamine, most of which are substituted with one or two sulfate groups. Immobilized heparin has two main modes of interaction with proteins. It can operate as an affinity ligand; e.g.
  • Heparin has also a function as a high capacity cation exchanger due to its anionic sulphate groups.
  • the column was operated by using a syringe.
  • Recommended elution conditions for both cases comprised increasing the ionic strength by using a step gradient of 2M NaCl in which the Binding buffer was 10 mM sodium phosphate pH ⁇ 7, and the Elution buffer was 10 mM sodium phosphate, 2 M NaCl, pH n
  • a 25 ml syringe was filled with binding buffer.
  • the stopper was removed and the column was connected to the syringe with the provided adapter "drop to drop” to avoid introducing air into column.
  • the sample was then prepared as described above and applied by using a syringe fitted to the luer adaptor by pumping onto the column.
  • Sample Loading and Running Conditions 15 ⁇ g of sample were dissolved in 20 ⁇ l Sample buffer (Sample, 2.5 ⁇ l NuPAGE
  • the upper buffer chamber was filled with 200 ml IX NuPAGE SDS running buffer (MES SDS running Buffer was prepared by adding 50 ml of 2OX NuPAGE MES
  • LC-MS For identification of secreted proteins our proteomics studies were also performed using an LC/MS system named multidimensional protein identification technology (MudPIT), which combines multidimensional liquid chromatography with electro-spray ionization tandem mass spectrometry.
  • our multidimensional liquid chromatography method integrates a strong cation-exchange (SCX) resin and reversed-phase resin in a biphasic column.
  • SCX cation-exchange
  • Each MudPIT analysis was done in duplicate and separation was reproducible within 0.5% between two analyses. Furthermore, a dynamic range of 10000 to 1 between the most abundant and least abundant proteins/peptides in a complex peptide mixture has been demonstrated.
  • the MudPIT system included a 4 cm x 50 - ⁇ m i.d.
  • the micro- SPE stage allowed solution to be loaded onto the nanoLC column at approximately 8 ⁇ L miiT 1 which required ⁇ 2 min to load a 10 ⁇ L solution with a sample loss of ⁇ 5% (due to the syringe and valve adapters).
  • the separation is conducted at a constant pressure of 10,000 psi.
  • the long 3- ⁇ m particle packed 15- ⁇ m-i.d. capillary provides a separation peak capacity of approximately 10 3 .
  • the column is connected by a zero dead volume stainless steel union fitting to a replaceable nanoESI emitter made from a 10- ⁇ m -i.d. X 150- ⁇ m- o.d. fused silica capillary with an approximately 2- ⁇ m- i.d orifice for highly efficient ionization of the eluting peptide.
  • the ESI source is interfaced to either an FTICR MS or an ion trap MS/MS for peptide/protein detection and identification.
  • An FTICR mass spectrometer was used for single-stage MS based upon high-accuracy mass measurements and the use of relative retention time (RRT) information, and a Finnigan ion trap mass spectrometer (LCQ XP, ThermoQuest Corp., San Jose, CA) was used for MS/MS.
  • RRT relative retention time
  • LCQ XP Finnigan ion trap mass spectrometer
  • Polyclonal antibody to the beta-cell failure marker PCl is generated for further use of the antibody in the measurement of serum and plasma and blood levels of PCl by immunodetection assays, e.g. Western Blotting and ELISA.
  • recombinant expression of the protein is performed for obtaining immunogens.
  • the expression is done applying a combination of the RTS 100 expression system and E.coli.
  • the DNA sequence is analyzed and recommendations for high yield cDNA silent mutational variants and respective
  • PCR-primer sequences are obtained using the "ProteoExpert RTS E.coli HY” system. This is a commercial web based service (www.proteoexpert.com). Using the recommended primer pairs, the "RTS 100 E. coli Linear Template Generation Set, His-tag” (Roche Diagnostics GmbH, Mannheim, Germany, Cat.No. 3186237) system to generate linear PCR templates from the cDNA and for in-vitro transcription and expression of the nucleotide sequence coding for the PCl protein is used. For Western-blot detection and later purification, the expressed protein contains a His-tag. The best expressing variant is identified. AU steps from PCR to expression and detection are carried out according to the instructions of the manufacturer.
  • the respective PCR product containing all necessary T7 regulatory regions (promoter, ribosomal binding site and T7 terminator) is cloned into thepBAD TOPO ® vector (Invitrogen, Düsseldorf, Germany, Cat. No. K 4300/01) following the manufacturer's instructions.
  • the construct is transformed into E. coli BL 21 (DE 3) (Studier, F. W., et al., Methods Enzymol. 185 (1990) 60-89) and the transformed bacteria are cultivated in a 1 1 batch for protein expression.
  • His-PCl fusion protein Purification of His-PCl fusion protein is done following standard procedures on a Ni-chelate column. Briefly, 1 1 of bacteria culture containing the expression vector for the His-PCl fusion protein is pelleted by centrifugation. The cell pellet is resuspended in lysis buffer, containing phosphate, pH 8.0, 7 M guanidium chloride, imidazole and thioglycerole, followed by homogenization using a Ultra-Turrax ® . Insoluble material is pelleted by high speed centrifugation and the supernatant is applied to a Ni-chelate chromatographic column. The column is washed with several bed volumes of lysis buffer followed by washes with buffer, containing phosphate, pH 8.0 and Urea. Finally, bound antigen is eluted using a phosphate buffer containing SDS under acidic conditions.
  • Spleen cells of the mice immunized according to a) are fused with myeloma cells according to Galfre, G., and Milstein, C, Methods in Enzymology 73 (1981) 3-46.
  • ca. l*10 8 spleen cells of the immunized mouse are mixed with 2x10 7 myeloma cells (P3X63-Ag8-653, ATCC CRL1580) and centrifuged (10 min at 300 g and 4°C). The cells are then washed once with RPMI 1640 medium without fetal calf serum (FCS) and centrifuged again at 400 g in a 50 ml conical tube.
  • FCS fetal calf serum
  • the sedimented cells are taken up in RPMI 1640 medium containing 10% FCS and sown in hypoxanthine-azaserine selection medium (100 mmol/1 hypoxanthine, 1 ⁇ g/ml azaserine in RPMI 1640+10% FCS).
  • Interleukin 6 at 100 U/ml is added to the medium as a growth factor.
  • PCl -positive primary cultures are cloned in 96- well cell culture plates by means of a fluorescence activated cell sorter. In this process again interleukin 6 at 100 U/ml is added to the medium as a growth additive.
  • the hybridoma cells obtained are sown at a density of IxIO 5 cells per ml in RPMI
  • 1640 medium containing 10% FCS and proliferated for 7 days in a fermenter (Thermodux Co., Wertheim/Main, Model MCS- 104XL, Order No. 144-050).
  • concentrations of 100 ⁇ g monoclonal antibody per ml are obtained in the culture supernatant. Purification of this antibody from the culture supernatant is carried out by conventional methods in protein chemistry (e.g. according to Bruck, C, et al., Methods in Enzymology 121 (1986) 587-695).
  • rabbit serum is diluted with 4 volumes of acetate buffer (60 mM, pH 4.0). The pH is adjusted to 4.5 with 2 M Tris-base. Caprylic acid (25 ⁇ l/ml of diluted sample) is added drop- wise under vigorous stirring. After 30 min the sample is centrifuged (13,000 x g, 30 min, 4°C), the pellet discarded and the supernatant collected.
  • the pH of the supernatant is adjusted to 7.5 by the addition of 2 M Tris-base and filtered
  • the immunoglobulin in the supernatant is precipitated under vigorous stirring by the drop-wise addition of a 4 M ammonium sulfate solution to a final concentration of 2 M.
  • the precipitated immunoglobulins are collected by centrifugation (8000 x g, 15 min,
  • the supernatant is discarded.
  • the pellet is dissolved in 10 mM NaH 2 PCVNaOH, pH 7.5,
  • the dialysate is centrifuged (13,000 x g, 15 min, 4°C) and filtered (0.2 ⁇ m).
  • Polyclonal rabbit IgG is brought to 10 mg/ml in 10 mM NaH 2 PO 4 /NaOH, pH 7.5, 30 mM NaCl. Per ml IgG solution 50 ⁇ l Biotin -N-hydroxysuccinimide (3.6 mg/ml in DMSO) are added. After 30 min at room temperature, the sample is chromatographed on Superdex 200 (10 mM NaH 2 PO 4 /NaOH, pH 7.5, 30 mM NaCl). The fraction containing biotinylated IgG are collected. Monoclonal antibodies have been biotinylated according to the same procedure.
  • Polyclonal rabbit IgG is brought to 10 mg/ml in 10 mM NaH 2 PO 4 /NaOH, 30 mM NaCl, pH 7.5. Per ml IgG solution 50 ⁇ l digoxigenin-3-O-methylcarbonyl- ⁇ - aminocaproic acid-N-hydroxysuccinimide ester (Roche Diagnostics, Mannheim, Germany, Cat. No. 1 333 054) (3.8 mg/ml in DMSO) are added. After 30 min at room temperature, the sample is chromatographed on Superdex® 200 (10 mM
  • Protein samples enriched and isolated from the -medium by Heparin columns were solved in sample buffer consisting of 10 mM Tris-HCl (pH 7.5), 150 mM NaCl, 0.05 % Tween 20, 1 % SDS, and centrifuged at 12,000 g for 10 min at 4°C.
  • sample buffer consisting of 10 mM Tris-HCl (pH 7.5), 150 mM NaCl, 0.05 % Tween 20, 1 % SDS, and centrifuged at 12,000 g for 10 min at 4°C.
  • the protein concentration of the supernatant was measured by Bradford using a standard curve constructed from a range of known bovine serum albumin standards.
  • sample buffer 60 mM Tris-HCl, 2% SDS, 0.1% bromphenol blue, 25% glycerol, and 14.4 mM 2-mercaptoethanol, pH 6.8
  • sample buffer 60 mM Tris-HCl, 2% SDS, 0.1% bromphenol blue, 25% glycerol, and 14.4 mM 2-mercaptoethanol, pH 6.8
  • sample buffer 60 mM Tris-HCl, 2% SDS, 0.1% bromphenol blue, 25% glycerol, and 14.4 mM 2-mercaptoethanol, pH 6.8
  • sample buffer 60 mM Tris-HCl, 2% SDS, 0.1% bromphenol blue, 25% glycerol, and 14.4 mM 2-mercaptoethanol, pH 6.8
  • samples were separated by 12.5% homogenous ExcelGel SDS gels (Amersham Bioscience) and electro transferred onto Nitrocellulose membranes.
  • blocking solution 10 mM Tris-HCl, pH 7.5, 150 mM NaCl, 0.05%
  • membranes were incubated with a horseradish peroxidase conjugated anti-rabbit IgG (H+L), anti-mouse IgGi and anti-mouse IgG2a (Southern Biotechnology Associates, Inc., Birmingham, AL), respectively, for 1 hr at room temperature.
  • H+L horseradish peroxidase conjugated anti-rabbit IgG
  • anti-mouse IgGi and anti-mouse IgG2a Southern Biotechnology Associates, Inc., Birmingham, AL
  • Membranes were washed 3 times for 10 min and antigen-antibody complexes were visualized by an enhanced chemiluminescence's reagent (Western Lightning TM, PerkinElmer Life Sciences, Inc., Boston, MA) on an X-ray film according to the manufacturer's protocol.
  • aliquots of the anti-PCl polyclonal antibody are conjugated with biotin and digoxygenin, respectively.
  • Streptavidin-coated 96-well microtiter plates are incubated with 100 ⁇ l biotinylated anti-PCl polyclonal antibody for 60 min at 10 ⁇ g/ml in 10 mM phosphate, pH 7.4, 1% BSA, 0.9% NaCl and 0.1% Tween 20. After incubation, plates are washed three times with 0.9% NaCl , 0.1% Tween 20. Wells are then incubated for 2 h with either a serial dilution of the recombinant protein (see Example 2) as standard antigen or with diluted plasma samples from patients. After binding of PCl, plates are washed three times with 0.9% NaCl , 0.1% Tween 20.
  • wells are incubated with 100 ⁇ l of digoxygenylated anti-PCl polyclonal antibody for 60 min at 10 ⁇ g/ml in 10 mM phosphate, pH 7.4, 1% BSA, 0.9% NaCl and 0.1% Tween 20. Thereafter, plates are washed three times to remove unbound antibody.
  • wells are incubated with 20 mU/ml anti-digoxigenin-POD conjugates (Roche Diagnostics GmbH, Mannheim, Germany, Catalog No. 1633716) for 60 min in 10 mM phosphate, pH 7.4, 1% BSA, 0.9% NaCl and 0.1% Tween 20. Plates are subsequently washed three times with the same buffer.
  • ABTS solution (Roche Diagnostics GmbH, Mannheim, Germany, Catalog No. 11685767) and OD is measured after 30-60 min at 405 nm with an ELISA reader.
  • Clinical utility of the novel marker PCl is assessed by measuring its levels in 10 diabetic patients depending on injections of exogeneous insulin and comparing the levels with those measured in 10 patients with demonstrated normal beta cell function. Statistical analysis is performed by standard Student's t-test evaluation with values ⁇ 0.05 taken as significant.

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Abstract

L'invention concerne le contrôle de la progression de la maladie et le diagnostic de la défaillance des cellules bêta pour le diabète, par mesure des niveaux de PC1 dans un échantillon liquide ; et le criblage de nouveaux composés pour la prévention et/ou le traitement du diabète.
PCT/EP2005/007855 2004-07-28 2005-07-19 Prohormone convertase 1 utilisee en tant que marqueur/cible pour la defaillance des cellules beta WO2006010531A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010072608A1 (fr) * 2008-12-22 2010-07-01 F. Hoffmann-La Roche Ag Polymorphisme de nucléotide unique de pcsk1 dans le diabète de type 2

Citations (4)

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Publication number Priority date Publication date Assignee Title
WO1997010504A1 (fr) * 1995-09-15 1997-03-20 Emory University Dosages radioimmunologiques par anticorps des propeptide/prohormone convertases pc1/3 et pc2
WO2000072885A2 (fr) * 1999-06-01 2000-12-07 Sarah Ferber Procedes d'induction d'une production regulee de l'hormone pancreatique dans des ilots non pancreatiques
US20040052928A1 (en) * 2002-09-06 2004-03-18 Ehud Gazit Peptides and methods using same for diagnosing and treating amyloid-associated diseases
US20040096923A1 (en) * 2002-11-15 2004-05-20 Echelon Biosciences Incorporated Lipid phosphatase assays in disease and drug discovery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997010504A1 (fr) * 1995-09-15 1997-03-20 Emory University Dosages radioimmunologiques par anticorps des propeptide/prohormone convertases pc1/3 et pc2
WO2000072885A2 (fr) * 1999-06-01 2000-12-07 Sarah Ferber Procedes d'induction d'une production regulee de l'hormone pancreatique dans des ilots non pancreatiques
US20040052928A1 (en) * 2002-09-06 2004-03-18 Ehud Gazit Peptides and methods using same for diagnosing and treating amyloid-associated diseases
US20040096923A1 (en) * 2002-11-15 2004-05-20 Echelon Biosciences Incorporated Lipid phosphatase assays in disease and drug discovery

Non-Patent Citations (2)

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Title
APLETALINA EKATERINA ET AL: "Identification of inhibitors of prohormone convertases 1 and 2 using a peptide combinatorial library", JOURNAL OF BIOLOGICAL CHEMISTRY, vol. 273, no. 41, 9 October 1998 (1998-10-09), pages 26589 - 26595, XP002355258, ISSN: 0021-9258 *
BASAK AJOY ET AL: "Inhibition of proprotein convertases-1, -7 and furin by diterpines of Andrographis paniculata and their succinoyl esters", BIOCHEMICAL JOURNAL, vol. 338, no. 1, 15 February 1999 (1999-02-15), pages 107 - 113, XP002355259, ISSN: 0264-6021 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010072608A1 (fr) * 2008-12-22 2010-07-01 F. Hoffmann-La Roche Ag Polymorphisme de nucléotide unique de pcsk1 dans le diabète de type 2

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