WO1997002004A2

WO1997002004A2 - Methods for treating diabetes

Info

Publication number: WO1997002004A2
Application number: PCT/US1996/010983
Authority: WO
Inventors: Thomas W. Stephens
Original assignee: Eli Lilly And Company
Priority date: 1995-06-30
Filing date: 1996-06-26
Publication date: 1997-01-23
Also published as: AU695934B2; CN1195293A; NO976063L; WO1997002004A3; EP0836479A2; HUP9802609A2; AU6479596A; US5756461A; KR19990028388A; MX9800133A; NO976063D0; PL324284A1; CA2225454A1; CZ416797A3; IL122718A0; EA199800104A1; JPH11508895A

Abstract

This invention describes methods of treating diabetes in obese type II diabetic patients. Specifically, methods of treating obese type II diabetics with varying levels of endogenous leptin is claimed.

Description

METHODS FOR TREATING DIABETES

Diabetes mellitus is a metabolic disorder characterized by the failure of body tissues to store carbohydrates at the normal rate. Resistance to the action of insulin is the most important factor to Type II diabetes. When this resistance exceeds the capacity of the beta cells to produce insulin, a person becomes diabetic. During the last 70 years people suffering from diabetes have been greatly aided by receiving controlled amounts of insulin. Obesity, particularly upper body obesity, is often associated with non-insulin-dependent diabetes mellitus (NIDDM) . These so called Type II diabetics do not have an absolute requirement for insulin as their beta cells ■ are able to secrete insulin, albeit often at diminished levels. In addition such patients are often obese and may demonstrate an inability to respond to insulin.

It is well known that a regimen of diet and exercise leading to weight loss is the best approach for treating obese type II diabetics. Unfortunately, these regimens are usually unsuccessful. Failure to loss weight may be due to genetically inherited factors that contribute to increased appetite, a preference for high calorie foods, reduced physical activity, and an increased lipogenic metabolism. People inheriting such genetic predispositions are prone to obesity and often become type II diabetics, regardless of their efforts to combat the condition. The ob l ob mouse is a model of obesity and diabetes that is known to carry an autosomal recessive trait linked to a mutation in the sixth chromosome. Recently, Yiying Zhang and co-workers published the positional cloning of the mouse gene ( ob) linked with this condition. Yiying Zhang et al . Nature 372 : 425-32 (1994) . This report disclosed a gene coding for a 167 amino acid protein (hereinafter leptin) with a 21 amino acid signal peptide that is exclusively expressed in adipose tissue. Circulating levels of leptin in obese individuals have been shown to vary widely. Consequently, it is now believed that a subpopulation of obese type II diabetics are particularly amenable to treatment with leptin. Pharmacological agents which are biologically active and mimic the activity of leptin are therefore useful for treating obese type II diabetics, particularly those with abnormally high or low levels of circulating leptin.

One aspect of the present invention is a method of treating or preventing diabetes which comprises administering to an obese type II diabetic an effective amount of leptin, leptin mimetic, or a pharmaceutically acceptable salt thereof. In a preferred embodiment, the invention includes methods for treating obese type II diabetics having low endogenous levels of leptin.

Obesity refers to a condition in which the individual has a body mass index of greater than 27 kilograms per square meter.

Leptin refers to the protein produced from the obesity gene following transcription and deletions of introns, translation to a protein and processing to the mature protein with secretory signal peptide removed, e.g., from the N-terminal valine-proline to the C-terminal cysteine of the mature protein. Mouse and human leptin protein sequences are published in Zhang et al . Nature 372 : 425-32 (1994) . The rat leptin sequence is published in Murakami et al., Biochemical and Biophysical Research Comm. 209(3): 944- 52 (1995) . In human, murine and rat leptin the Cys associated with di-sulfide formation is positions 96 and 145. However, particularly with murine and human leptin, a desGln(28) variant has been observed. Hence, the Cys residues associated with di-sulfide bond formation may be at positions 95 or 96 and at position 145 or 146. Leptin may also be referred to throughout this specification as obesity protein, OB, or ob gene product. Leptin therefore includes SEQ ID NOs.1-6. Those skilled in the art will recognize that certain amino acids are prone to rearrangement. For example, Asp may rearrange to aspartimide and isoasparigine as described in I. Schόn, et al. , International Journal of Peotide and Protein Research, 14:485-94 (1979) and references cited therein. These rearrangement derivatives are included within the scope of the present invention. Unless otherwise indicated the amino acids are in the L configuration.

Preferred forms of leptin useful in the presently claimed method are the native sequences. The use of human leptin is more preferred. Most preferred leptins useful in the present method include proteins of SEQ ID NOS:1-6.

Murine Leotin SEQ ID NO: 1

Val Pro lie Gin Lys Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr 1 5 10 15 lie Val Thr Arg lie Asn Asp lie Ser His Thr Xaa Ser Val Ser Ser

20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe lie Pro Gly Leu His Pro lie 35 40 45

Leu Thr Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin lie 50 55 60

Leu Thr Ser Met Pro Ser Arg Asn Val lie Gin lie Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys 85 90 95 His Leu Pro Gin Ala Ser Gly Leu Glu Thr Leu Glu Ser Leu Gly Gly

100 105 110

Val Leu Glu Ala Ser Gly Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Gin Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145 wherein:

Xaa at position 28 is Gin or absent, Porcine Leptin SEQ ID NO: 2

Val Pro lie Trp Arg Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr 1 5 10 15 lie Val Thr Arg lie Ser Asp lie Ser His Met Gin Ser Val Ser Ser 20 25 30 Lys Gin Arg Val Thr Gly Leu Asp Phe lie Pro Gly Leu His Pro Val 35 40 45

Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala lie Tyr Gin Gin lie 50 55 60

Leu Thr Ser Leu Pro Ser Arg Asn Val lie Gin lie Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Ser Ser Lys Ser Cys 85 90 95

Pro Leu Pro Gin Ala Arg Ala Leu Glu Thr Leu Glu Ser Leu Gly Gly 100 105 110 Val Leu Glu Ala Ser Leu Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ala Leu Gin Asp Met Leu Arg Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145

Bovine Leptin SEQ ID NO : 3

Val Pro lie Cys Lys Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr 1 5 10 15 He Val Thr Arg He Asn Asp He Ser His Thr Xaa Ser Val Ser Ser

20 25 30

Lys Gin Arg Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro Leu

35 40 45

Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala He Tyr Gin Gin He

50 55 60

Leu Thr Ser Leu Pro Ser Arg Asn Val Val Gin He Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Ala Ser Lys Ser Cys 85 90 95 Pro Leu Pro Gin Val Arg Ala Leu Glu Ser Leu Glu Ser Leu Gly Val 100 105 110

Val Leu Glu Ala Ser Leu Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Arg Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145

wherein Xaa at position 28 is Gin or absent.

Human Leptin SEQ ID NO : 4

Val Pro He Gin Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Asn Asp He Ser His Xaa Xaa Ser Val Ser Ser 20 25 30 Lys Gin Lys Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He

35 40 45

Leu Thr Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin He

50 55 60

Leu Thr Ser Met Pro Ser Arg Asn Val He Gin He Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys 85 90 95

His Leu Pro Trp Ala Ser Gly Leu Glu Thr Leu Asp Ser Leu Gly Gly

100 105 110 Val Leu Glu Ala Ser Gly Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145 Gly Cys

wherein: Xaa at position 27 is Thr or Ala; and

Xaa at position 28 is Gin or absent.

Rhesus Leptin SEQ ID NO : 5

Val Pro He Gin Lys Val Gin Ser Asp Thr Lys Thr Leu He Lys 1 5 10 15

Thr He Val Thr Arg He Asn Asp He Ser His Thr Gin Ser Val 20 25 30

Ser Ser Lys Gin Arg Val Thr Gly Leu Asp Phe He Pro Gly Leu 35 40 45

His Pro Val Leu Thr Leu Ser Gin Met Asp Gin Thr Leu Ala He 50 55 60 Tyr Gin Gin He Leu He Asn Leu Pro Ser Arg Asn Val He Gin

65 70 75

He Ser Asn Asp Leu Glu Asn Leu Arg Asp Leu Leu His Leu Leu 80 85 90

Ala Phe Ser Lys Ser Cys His Leu Pro Leu Ala Ser Gly Leu Glu 95 100 105

Thr Leu Glu Ser Leu Gly Asp Val Leu Glu Ala Ser Leu Tyr Ser 110 115 120

Thr Glu Val Val Ala Leu Ser Arg Leu Gin Gly Ser Leu Gin Asp 125 130 135 Met Leu Trp Gin Leu Asp Leu Ser Pro Gly Cys

140 145

Rat Leptin

SEQ ID NO: 6 Val Pro He His Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Asn Asp He Ser His Thr Gin Ser Val Ser Ala 20 25 30

Arg Gin Arg Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He 35 40 45

Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60

Leu Thr Ser Leu Pro Ser Gin Asn Val Leu Gin He Ala His Asp Leu 65 70 75 80 Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Phe Ser Lys Ser Cys

85 90 95

Ser Leu Pro Gin Thr Arg Gly Leu Gin Lys Pro Glu Ser Leu Asp Gly 100 105 110

Val Leu Glu Ala Ser Leu Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp He Leu Gin Gin Leu Asp Leu Ser Pro 130 135 140

Glu Cys

145

In addition to the above identified protein sequences, it is frequently considered expeditious to prepare such anti diabetic proteins with a one or two amino acid leader sequence, especially with a methionine containing leader. Two frequently employed leaders are Met-Arg and Met- Asp. Such proteins may be identified infra as Met-Arg-leptin or Met-Asp-leptin or may be identified by Met-Arg-SEQ ID NO:X, where X is 1 to 6.

Leptin mimetics and fragments are also useful in the methods of the present invention. Leptin mimetics are generally defined by Formula (I) (SEQ ID NO:7) as follows:

Val Pro He Gin Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Xaa Asp He Ser His Xaa Xaa Ser Val Ser Ser 20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He

35 40 45 Leu Thr Leu Ser Lys Xaa Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60

Leu Thr Ser Xaa Pro Ser Arg Xaa Val He Gin He Xaa Asn Asp Leu

65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys

85 90 95

His Leu Pro Trp Ala Ser Gly Leu Glu Thr Leu Asp Ser Leu Gly Gly 100 105 110

Val Leu Glu Ala Ser Xaa Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125 Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145 Gly Cys wherein :

Xaa at position 22 is Asn, Asp or Glu;

Xaa at position 27 is Thr or Ala;

Xaa at position 28 is Gin, Glu, or absent; Xaa at position 54 is Met or Ala;

Xaa at position 68 is Met or Leu;

Xaa at position 72 Asn, Asp or Glu;

Xaa at position 77 is Ser or Ala;

Xaa at position 118 is Gly or Leu; said protein having at least one substitution selected from the group consisting of:

His at position 97 is replaced with Ser or Pro;

Trp at position 100 is replaced with Gin, Ala or Leu;

Ala at position 101 is replaced with Thr or Val; Ser at position 102 is replaced with Arg;

Gly at position 103 is replaced with Ala;

Glu at position 105 is replaced with Gin;

Thr at position 106 is replaced with Lys or Ser;

Leu at position 107 is replaced with Pro; Asp at position 108 is replaced with Glu; or

Gly at position 111 is replaced with Asp.

Preferably, leptin mimetics are those of Formula (II) (SEQ ID NO:8) as follows:

100 105 110

Val Leu Glu Ala Ser Xaa Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145 Gly Cys

wherein:

Xaa at position 27 is Thr or Ala;

Xaa at position 77 is Ser or Ala; Xaa at position 118 is Gly or Leu; said protein having at least one substitution, preferably having one to five substitutions and, most preferably, one to two substitutions selected from the group consisting of:

His at position 97 is replaced with Ser; Trp at position 100 is replaced with Gin;

Ala at position 101 is replaced with Thr;

Glu at position 105 is replaced with Gin;

Thr at position 106 is replaced with Lys;

Gly at position 111 is replaced with Asp.

Examples of preferred proteins of the present invention include proteins of SEQ ID NO: 8, wherein Xaa at position 27 is Thr; Xaa at position 77 is Ser; Xaa at position 118 is Gly; and the amino acid residues at positions 97, 100, 101, 105, 106, 107, 108, and 111 are as follows in Table I. The native human sequence is provided as a comparison to the proteins employed in the methods of the present invention.

Table I

Amino Acid Position

Compound 97 100 101 105 106 107 108 111

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143

180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215

216 Ser Gin Thr Gin Thr Leu Glu Gly

217 Ser Gin Thr Gin Thr Pro Asp Gly

218 Ser Gin Thr Gin Lys Leu Asp Gly

219 His Trp Thr Gin Lys Pro Glu Asp

220 His Gin Ala Gin Lys Pro Glu Asp

221 His Gin Thr Glu Lys Pro Glu Asp

222 His Gin Thr Gin Thr Pro Glu Asp

223 His Gin Thr Gin Lys Leu Glu Asp

224 His Gin Thr Gin Lys Pro Asp Asp

225 His Gin Thr Gin Lys Pro Glu Gly

226 Ser Trp Ala Gin Lys Pro Glu Asp

227 Ser Trp Thr Glu Lys Pro Glu Asp

228 Ser Trp Thr Gin Thr Pro Glu Asp

229 Ser Trp Thr Gin Lys Leu Glu Asp

230 Ser Trp Thr Gin Lys Pro Asp Asp

231 Ser Trp Thr Gin Lys Pro Glu Gly

232 Ser Gin Ala Glu Lys Pro Glu Asp

233 Ser Gin Ala Gin Thr Pro Glu Asp

234 Ser Gin Ala Gin Lys Leu Glu Asp

235 Ser Gin Ala Gin Lys Pro Asp Asp

236 Ser Gin Ala Gin Lys Pro Glu Gly

237 Ser Gin Thr Glu Thr Pro Glu Asp

238 Ser Gin Thr Glu Lys Leu Glu Asp

239 Ser Gin Thr Glu Lys Pro Asp Asp

240 Ser Gin Thr Glu Lys Pro Glu Gly

241 Ser Gin Thr Gin Thr Leu Glu Asp

242 Ser Gin Thr Gin Thr Pro Asp Asp

243 Ser Gin Thr Gin Thr Pro Glu Gly

244 Ser Gin Thr Gin Lys Leu Asp Asp

245 Ser Gin Thr Gin Lys Leu Glu Gly

246 Ser Gin Thr Gin Lys Pro Asp Gly

247 His Gin Thr Gin Lys Pro Glu Asp

248 Ser Trp Thr Gin Lys Pro Glu Asp

249 Ser Gin Ala Gin Lys Pro Glu Asp

250 Ser Gin Thr Glu Lys Pro Glu Asp

251 Ser Gin Thr Gin Thr Pro Glu Asp 252 253 254

255

Other preferred proteins are those wherein Xaa at position 27 is Ala; Xaa at position 77 is Ser; Xaa at position 118 is Gly; and the amino residues at positions 97, 100, 101, 105, 106, 107, 108 and 111 are as described in Table I.

The present invention provides biologically active proteins that provide effective treatment for obese type II diabetics. Unexpectedly, the leptin proteins of Table I have improved properties due to specific substitutions to the human obesity protein. These proteins are more stable than both the mouse and human obesity protein and, therefore, represent superior therapeutic agents.

Experiments were performed with five to six month old male, inbred normal ICR mice, inbred normal ( ob/+) , obese- diabetic mice ( ob/ ob) from the Jackson Laboratories (Bar Harbor, Maine) or Harlan (England) , and obese-diabetic ( db/db) mice.

Both normal and diabetic mice were housed three or six per plastic cage (with bedding) and water and feed were available ad libi tum. The temperature of animal rooms was maintained at 23 ± 2°C and lights were on from 0600 to 1800 h. Blood samples were collected from the tail vein. The most closely related biological test is, therefore, to inject the test article by any of several routes of administration (e.g., i.v., s.c, i.p., or by minipump or cannula) and then to monitor food and water consumption, body weight gain, plasma chemistry or hormones (glucose, insulin, ACTH, corticosterone, GH, T4) over various time periods. Suitable test animals include normal mice (ICR, etc.) and obese mice ( ob/ob, Avy/a, KK-Ay, tubby, fat) . Controls for nonspecific effects for these injections can be done using vehicle with or without test articles of similar composition in the same animal monitoring the same parameters or the test article itself in animals that are thought to lack the receptor (db/db mice, fa/fa or cp/cp rats) .

Blood glucose levels were measured by a glucose oxidase method or a coupled hexokinase method. Plasma insulin was determined with radioimmunoassay kits using rat insulin as the standard. Plasma triglycerides were measured using commercial kits with glycerol as the standard.

The foregoing studies demonstrated that leptin and leptin mimetis, regulated food intake and body weight in normal ICR and genetically obese ob/ob mice. Chronic administration of leptin and leptin mimetics to ob/ob mice totally ameliorated the diabetic state of these animals showing the potential promise for these anti-diabetic proteins as a treatment for obese type II diabetics. Thus, the present invention provides methods for treating obese type II diabetics, particularly those with low circulating levels of leptin.

The compounds of the present invention may be produced by well known chemical procedures, such as solution or solid-phase peptide synthesis, or semi-synthesis in solution beginning with protein fragments coupled through conventional solution methods. Such methods are well known in the art and may be found in general texts in the area such as H. Dugas and C. Penney, BIOORGANIC CHEMISTRY, (1981) at pages 54-92.

Proteins useful in the presently claimed methods also may be prepared by well known recombinant DNA techniques such as those described in Maniatis, et al. (1988) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York or Current Protocols in Molecular Biology (1989) and supplements. Techniques for making substitutional mutations at predetermined sites in DNA having a known sequence are well known, for example M13 primer mutagenesis. The mutations that might be made in the DNA encoding the present anti-diabetic proteins must not place the sequence out of reading frame and preferably will not create complementary regions that could produce secondary mRNA structure. See, DeBoer, et al. , European Patent Publication, 075,444 A (1983) . The present invention provides a method for treating obese type II diabetics. The method comprises administering an effective amount of an leptin or leptin mimetic in a dose between about 1 and 10,000 μg/kg. A preferred dose is from about 20 to 10,000 μg/kg. A more preferred dose is from about 200 to 600 μg/kg. In practicing this method, anti-diabetic proteins can be administered in a single daily dose or in multiple doses per day. The treatment regime may require administration over extended periods of time. The amount per administered dose or the total amount administered will be determined by the physician and depend on such factors as the mass of the patient, the age and general health of the patient and the tolerance of the patient to the compound.

The instant invention further provides pharmaceutical formulations comprising compounds of the present invention. The proteins, preferably in the form of a pharmaceutically acceptable salt, can be formulated for parenteral administration. For example, compounds can be admixed with conventional pharmaceutical carriers and excipients. The compositions comprising claimed proteins contain from about 0.1 to 90% by weight of the active protein, preferably in a soluble form, and more generally from about 10 to 30%. Furthermore, the present proteins may be administered alone or in combination with other anti- obesity agents or agents useful in treating diabetes.

For intravenous use, the protein is administered in commonly used intravenous fluids and administered by infusion. For intramuscular preparations, a sterile formulation, preferably a suitable soluble salt form of the protein, for example the hydrochloride salt, can be dissolved and administered in a pharmaceutical diluent such as pyrogen- free water or physiological saline. A suitable insoluble form of the compound may be prepared and administered as a suspension in an aqueous base or a pharmaceutically acceptable oil base, e.g. an ester of a long chain fatty acid such as ethyl oleate. In a preferred embodiment, the present invention provides a method for treating obese type II diabetics with low leptin levels, though diabetic patients with high endogenous leptin levels may also benefit from the presently claimed methods. Methods for assaying serum and plasma leptin levels may be accomplished using standard antibody- based methodologies. Leptin assay kits are also commercially available from Linco Research, Inc. (14 Research Park Dr., St Louis, MO 63304)

Treating obese type II diabetics having leptin levels between 0 and 80 ng/ml is preferred. More preferred is to treat obese type II diabetics having leptin levels between 0 and 50 ng/ml. More highly preferred is to. treat obese type II diabetics having leptin levels between 0 and 30 ng/ml. Most preferred is to treat obese type II diabetics having leptin levels between 0 and 15 ng/ml.

By way of illustration, the following examples are provided to help describe how to make and practice the various embodiments of the invention. These example are in no way meant to limit the scope of the invention.

Example 1

A DNA sequence encoding the following protein sequence:

Met-Arg-SEQ ID NO:4.

was obtained using standard PCR methodology from a human fat cell library (commercially available from CLONETECH) . Briefly, degenerate primers were designed based on the published amino acid sequence of the human ob gene. The primers were prepared for use in polymerase chain reaction (PCR) amplification methods using a Model 380A DNA synthesizers (PE-Applied Biosystems, Inc., 850 Lincoln Center Drive, Foster City, CA 94404) . Forward primers OB.F1M (5-GG GG CAT ATG AGG GTA CCT ATC CAG AAA GTC CAG GAT GAC AC)and OB.F2H (5-GG GG CAT ATG AGG GTA CCC ATC CAG AAG GTG CAG GAC GA) (and reverse primers OB.RlM (5-GG GG GGATC GAT AAT TTA GCA TCC AGG GCT AAG ATC CAA CTG CCA AAG CAT) and OB.R2H (5-GG GG GGATC CTA TTA GCA CCC GGG AGA CAG GTC CAG CTG CCA CAA CAT) were mixed together with a PCR-ready human fat cell cDNA as the template (Clontech Laboratories, Inc., 4030 Fabian Way, Palo Alto, CA 94303; Item #7128-1) . The 2 sets of PCR amplifications were performed using 2.5 units of Amplitag DNA polymerase (Perkin Elmer Cetus) or 2 units of Vent DNA polymerase (New England Biolabs) in 100 uL reactions. PCR reactions contained 1 uL of human fat cell cDNA, 10 pmol of each primer (all four were mixed) . The following conditions were used for "Touchdown PCR": 2 cycles: 94°Cx30 sec, 60°Cx30 sec, 72°Cx45 sec 2 cycles: 94°Cx30 sec, 56°Cx30 sec, 72°Cx45 sec; 2cycles: 94°Cx30 sec, 52°Cx30 sec, 72°Cx45 sec; 2cycles: 94°Cx30 sec, 48°Cx30 sec, 72°Cx45 sec; 2 cycles: 94°Cx30 sec, 44°Cx30 sec, 72°Cx45 sec: 28 cycles 94°Cx30 sec, 52°Cx30 sec, 72°Cx45 sec The resultant PCR reactions products were run on a 1% agarose gel and a band of an approximate 450 bp in size was visualized by ethidium bromide staining. This band was present in both sets of PCR reactions. The bands were excised and reamplified using above conditions in 30 cycles (94x30 sec, 52x30, 72x45) . The PCR product obtained using Vent DNA polymerase was gel purified and cloned into a pCR- SCRIPT cloning vector (Stratagene) . The vector was then used to transform E. coli cells. Plasmid DNA was isolated from 20 white colonies of E. coli and samples from three clones were sequenced. Two such colonies, E. coli DHlθB/pOJ717 and E__ coli DHlOB/pOJ718 were deposited with the Northern Regional Research Laboratories (NRRL) under terms of the Budapest Treaty and are available under Accession Numbers B-21408 and B-21409 respectively. Example 2 Vector Construction

A plasmid containing the DNA sequence encoding a desired protein is constructed to include Ndel and BamHI restriction sites. The plasmid carrying the cloned PCR product is digested with Ndel and BamHI restriction enzymes. The small - 450bp fragment is gel-purified and ligated into the vector pRBl82 from which the coding sequence for A-C-B proinsulin is deleted. The ligation products are transformed into E. coli DHlOB (commercially available) and colonies growing on tryptone-yeast plates supplemented with 10 μg/mL of tetracycline are analyzed. Plasmid DNA is isolated, digested with Ndel and BamHI and the resulting fragments are separated by agarose gel electrophoresis. Plasmids containing the expected ~ 450bp Ndel to BamHI fragment are kept. E. coli B BL21 (DE3) are transformed with this second plasmid expression suitable for culture for protein production.

The techniques of transforming cells with the aforementioned vectors are well known in the art and may be found in such general references as Maniatis, et al. , MOLECULAR CLONING: A LABORATORY MANUAL, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (1988), or CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, (F. Ausabel, ed., 1989) and supplements thereof. The techniques involved in the transformation of E. coli cells used in the preferred practice of the invention as exemplified herein are well known in the art. The precise conditions under which the transformed E. coli cells are cultured is dependent on the nature of the E. coli host cell line and the expression or cloning vectors employed. For example, vectors which incorporate thermoinducible promoter-operator regions, such as the cl857 thermoinducible lambda-phage promoter-operator region, require a temperature shift from about 30°C to about 40°C in the culture conditions so as to induce protein synthesis. In the preferred embodiment of the invention E. coli K12 RV308 cells are employed as host cells but numerous other cell lines are available such as, but not limited to, E. coli K12 L201, L687, L693, L507, L640, L641, L695, L814 (E. coli B) . The transformed host cells are then plated on appropriate media under the selective pressure of the antibiotic corresponding to the resistance gene present on the expression plasmid. The cultures are then incubated for a time and temperature appropriate to the host cell line employed.

Proteins which are expressed in high-level bacterial expression systems characteristically aggregate in granules or inclusion bodies which contain high levels of the overexpressed protein. See. e.g.. Kreuger et al.. PROTEIN FOLDING, (Gierasch and King, eds., 1990) at pages 136-142, American Association for the Advancement of Science Publication No. 89-18S, Washington, D.C. Such protein aggregates must be solubilized to provide further purification and isolation of the desired protein product. ___!• variety of techniques using strongly denaturing solutions such as guanidinium-HCl and/or weakly denaturing solutions such as dithiothreitol (DTT) are used to solubilize the proteins.

Gradual removal of the denaturing agents (often by dialysis) in a solution allows the denatured protein to assume its native conformation. The particular conditions for denaturation and folding are determined by the particular protein expression system and/or the protein in question.

Preferably, the present proteins are expressed as Met-Arg-SEQ ID NO: X so that the expressed proteins may be readily converted to the claimed protein with cathepsin C (also known as diaminopeptidase) . The purification of proteins is by techniques known in the art and includes reverse phase chromatography, affinity chromatography, and size exclusion chromatography.

The claimed proteins contain two cysteine residues. Thus, a di-sulfide bond may be formed to stabilize the protein. The present invention includes proteins wherein the Cys at position 96 is crosslinked to Cys at position 146 as well as those proteins without such di-sulfide bonds.

In addition the proteins useful in the present invention may exist, particularly when formulated, as dimers, trimers, tetramers, and other multimers. Such multimers are included within the scope of the present invention.

Claims

I Claim :

1. Use of a leptin or leptin mimetic for the manufacture of a medicament for treating or preventing diabetes mellitus.

2. A method of Claim 1 wherein said leptin or leptin mimetic is selected from the group consisting of

(a) Val Pro lie Gin Lys Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr 1 5 10 15 lie Val Thr Arg lie Asn Asp lie Ser His Thr Xaa Ser Val Ser Ser 20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe lie Pro Gly Leu His Pro lie 35 40 45

Leu Thr Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin lie 50 55 60

Leu Thr Ser Met Pro Ser Arg Asn Val lie Gin lie Ser Asn Asp Leu 65 70 75 80 Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys

85 90 95

His Leu Pro Qln Ala Ser Gly Leu Glu Thr Leu Glu Ser Leu Gly Gly 100 105 110

Val Leu Glu Ala Ser Gly Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Gin Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145 wherein: Xaa at position 28 is Gin or absent;

(SEQ ID NO:l)

(b)

Val Pro lie Trp Arg Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr

1 5 10 15 lie Val Thr Arg lie Ser Asp lie Ser His Met Gin Ser Val Ser Ser

20 25 30

Lys Gin Arg Val Thr Gly Leu Asp Phe lie Pro Gly Leu His Pro Val 35 40 45

Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala lie Tyr Gin Gin lie 50 55 60

Leu Thr Ser Leu Pro Ser Arg Asn Val lie Gin lie Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Ser Ser Lys Ser Cys 85 90 95

Leu Gin Gly Ala Leu Gin Asp Met Leu Arg Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145 (SEQ ID NO: 2!

(C) Val Pro lie Cys Lys Val Gin Asp Asp Thr Lys Thr Leu lie Lys Thr 1 5 10 15 lie Val Thr Arg lie Asn Asp lie Ser His Thr Xaa Ser Val Ser Ser

20 25 30

Lys Gin Arg Val Thr Gly Leu Asp Phe lie Pro Gly Leu His Pro Leu 35 40 45

Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala lie Tyr Gin Gin lie 50 55 60

Leu Thr Ser Leu Pro Ser Arg Asn Val Val Gin lie Ser Asn Asp Leu 65 70 75 80 Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Ala Ser Lys Ser Cys

85 90 95

Pro Leu Pro Gin Val Arg Ala Leu Glu Ser Leu Glu Ser Leu Gly Val

100 105 110

Val Leu Glu Ala Ser Leu Tyr Ser Thr Glu Val Val Ala Leu Ser Arg

115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Arg Gin Leu Asp Leu Ser Pro 130 135 140

Gly Cys 145 wherein Xaa at position 28 is Gin or absent; (SEQ ID NO:3 (d)

Val Pro lie Gin Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Asn Asp He Ser His Xaa Xaa Ser Val Ser Ser 20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He 35 40 45

Leu Thr Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60

Leu Thr Ser Met Pro Ser Arg Asn Val He Gin He Ser Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys 85 90 95 His Leu Pro Trp Ala Ser Gly Leu Glu Thr Leu Asp Ser Leu Gly Gly

100 105 110

Val Leu Glu Ala Ser Gly Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145

Gly Cys

wherein :

Xaa at position 27 is Thr or Ala ; and Xaa at position 28 is Gin or absent ; ( SEQ ID NO : 4 )

( e )

Val Pro He Gin Lys Val Gin Ser Asp Thr Lys Thr Leu He Lys 1 5 10 15

Thr He Val Thr Arg He Asn Asp He Ser His Thr Gin Ser Val 20 25 30

Ser Ser Lys Gin Arg Val Thr Gly Leu Asp Phe He Pro Gly Leu 35 40 45

65 70 75

He Ser Asn Asp Leu Glu Asn Leu Arg Asp Leu Leu His Leu Leu 80 85 90 Ala Phe Ser Lys Ser Cys His Leu Pro Leu Ala Ser Gly Leu Glu 95 100 105

Thr Leu Glu Ser Leu Gly Asp Val Leu Glu Ala Ser Leu Tyr Ser 110 115 120

Thr Glu Val Val Ala Leu Ser Arg Leu Gin Gly Ser Leu Gin Asp 125 130 135

Met Leu Trp Gin Leu Asp Leu Ser Pro Gly Cys 140 145 (SEQ ID NO:5)

(f)

Val Pro He His Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Asn Asp He Ser His Thr Gin Ser Val Ser Ala 20 25 30

Arg Gin Arg Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He 35 40 45 Leu Ser Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60

Leu Thr Ser Leu Pro Ser Gin Asn Val Leu Gin He Ala His Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Leu Leu Ala Phe Ser Lys Ser Cys 85 90 95

Ser Leu Pro Gin Thr Arg Gly Leu Gin Lys Pro Glu Ser Leu Asp Gly 100 105 110

Val Leu Glu Ala Ser Leu Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125 Leu Gin Gly Ser Leu Gin Asp He Leu Gin Gin Leu Asp Leu Ser Pro 130 135 140

Glu Cys 145, (SEQ ID NO:5)

( g )

Val Pro He Gin Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr

1 5 10 15 He Val Thr Arg He Xaa Asp He Ser His Xaa Xaa Ser Val Ser Ser

20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He 35 40 45

Leu Thr Leu Ser Lys Xaa Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60 Leu Thr Ser Xaa Pro Ser Arg Xaa Val He Gin He Xaa Asn Asp Leu 65 70 75 80

Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys 85 90 95

His Leu Pro Trp Ala Ser Gly Leu Glu Thr Leu Asp Ser Leu Gly Gly 100 105 110

Val Leu Glu Ala Ser Xaa Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145 Gly Cys

wherein:

Xaa at position 22 is Asn, Asp or Glu;

Xaa at position 27 is Thr or Ala;

Xaa at position 28 is Gin, Glu, or absent;

Xaa at position 54 is Met or Ala; Xaa at position 68 is Met or Leu;

Xaa at position 72 Asn, Asp or Glu;

Xaa at position 77 is Ser or Ala;

His at position 97 is replaced with Ser or Pro;

Trp at position 100 is replaced with Gin, Ala or Leu;

Ala at position 101 is replaced with Thr or Val;

Ser at position 102 is replaced with Arg; Gly at position 103 is replaced with Ala;

Glu at position 105 is replaced with Gin;

Thr at position 106 is replaced with Lys or Ser;

Leu at position 107 is replaced with Pro;

Asp at position 108 is replaced with Glu; or Gly at position 111 is replaced with Asp; and, (SEQ ID NO:7)

(h) Val Pro He Gin Lys Val Gin Asp Asp Thr Lys Thr Leu He Lys Thr 1 5 10 15

He Val Thr Arg He Asn Asp He Ser His Xaa Gin Ser Val Ser Ser 20 25 30

Lys Gin Lys Val Thr Gly Leu Asp Phe He Pro Gly Leu His Pro He 35 40 45

Leu Thr Leu Ser Lys Met Asp Gin Thr Leu Ala Val Tyr Gin Gin He 50 55 60

Leu Thr Ser Met Pro Ser Arg Asn Val He Gin He Xaa Asn Asp Leu 65 70 75 80 Glu Asn Leu Arg Asp Leu Leu His Val Leu Ala Phe Ser Lys Ser Cys

85 90 95

His Leu Pro Trp Ala Ser Gly Leu Glu Thr Leu Asp Ser Leu Gly Gly 100 105 110

Val Leu Glu Ala Ser Xaa Tyr Ser Thr Glu Val Val Ala Leu Ser Arg 115 120 125

Leu Gin Gly Ser Leu Gin Asp Met Leu Trp Gin Leu Asp Leu Ser Pro 130 135 140

145 Gly Cys

wherein:

Xaa at position 27 is Thr or Ala;

Xaa at position 77 is Ser or Ala;

Xaa at position 118 is Gly or Leu; said protein having at least one substitution, preferably having one to five substitutions and, most preferably, one to two substitutions selected from the group consisting of:

His at position 97 is replaced with Ser;

Trp at position 100 is replaced with Gin;

Ala at position 101 is replaced with Thr; Glu at position 105 is replaced with Gin;

Thr at position 106 is replaced with Lys;

Leu at position 107 is replaced with Pro;

Asp at position 108 is replaced with Glu; or

Gly at position 111 is replaced with Asp, or a pharmaceutically acceptable salt or solvate thereof. (SEQ ID NO:8)

3. A method as claimed in any one of Claims 1 or 2 wherein the diabetes mellitus is associated with high endogenous leptin levels.

4. A method as claimed in any one of Claims 1 or 3 wherein the diabetes mellitus is associated with low endogenous leptin levels.

5. A method as claimed in any one of Claims 1 or 3 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 80 ng/ml.

6. A method as claimed in any one of Claims 1 or 3 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 50 ng/ml.

7. A method as claimed in any one of Claims 1 or 3 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 30 ng/ml.

8. A method as claimed in any one of Claims 1 or 3 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 15 ng/ml.

9. A method for treating or preventing diabetes mellitus which comprises administering to an afflicted patient a leptin or leptin mimetic.

10. The method of Claim 9 wherein said leptin or leptin mimetic is selected from the group consisting of:

SEQ ID NO:l, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO: 6, SEQ ID NO:7, and SEQ ID NO:8.

11. The method as claimed in any one of Claims 9 or 10 wherein the diabetes mellitus is associated with high endogenous leptin levels.

12. The method as claimed in any one of Claims 9 or 10 wherein the diabetes mellitus is associated with low endogenous leptin levels.

13. The method as claimed in any one of Claims 9 or 10 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 80 ng/ml.

14. The method as claimed in any one of Claims 9 or 10 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 50 ng/ml.

15. The method as claimed in any one of Claims 9 or 10 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 30 ng/ml.

16. The method as claimed in any one of Claims 9 or 10 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 15 ng/ml.

17. A formulation for treating or preventing diabetes mellitus, comprising as an active ingredient a leptin or leptin mimetic.

18. A formulation of Claim 17 wherein said leptin or leptin mimetic is selected from the group consisting of: SEQ ID NO:l, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO: , SEQ ID NO:5, SEQ ID NO: 6, SEQ ID NO:7, and SEQ ID NO:8.

19. The method as claimed in any one of Claims 17 or 18 wherein the diabetes mellitus is associated with low or high endogenous leptin levels.