A previously unknown putative polypeptide hormone identified as islet amyloid polypeptide (IAPP) was recently purified from islet amyloid (IA) of cats and humans with TYPE 2 diabetes mellitus (DM). In that IAPP -derived amyloid represents the most characteristic islet lesion in this from of DM in into the development of DM in cats and humans, information concerning the production and function of IAPP may provide new insights into the development of DM associated with aging. Our broad, long term objectives are to characterize the production and function of the IAPP-precursor, and to further elucidate the relationship of IAPP to DM. These objectives will be achieved through a series of experiments designed to: 1. Compare the primary chemical structure of IA-derived IAPP from multiple diabetic cats (by HPLC and amino acid sequence analysis) with that of IAPP or an IAPP precursor isolated (by affinity column separation) from pancreas or serum of normal cats. Specifically, we wish to investigate the possibility that certain structural aberrations in IAPP of diabetics are linked to transformation into amyloid fibrils; 2. Compare IAPP-precursor production in cats with and without DM (i.e., normal and normogylycemic cats with impaired glucose tolerance (IGT). Cats will be categorized by evaluations of fasting blood glucose, RIA insulin/glucagon levels and urinalysis prior to IV glucose tolerance test. LAPP-precursor production will be evaluated by immunocytochemical analysis of pancreatic B cells and by determination of serum IAPP using RIA. Pancreases will be histologically (Congo red) evaluated-red) evaluated to determine if LA deposits in nondiabetic cats are early reflections of IGT or a """"""""prediabetic"""""""" state; 3. Elucidate the molecular biology of IAPP production in normal islets, and also in IGT and DM. LAPP cDNA will be obtained from a lambda gt11 library (obtained after isolation of islet mRNA) using oligonucleotide probes and monospecific polyclonal antibodies. IAPP expression in normal IGT and DM cats will be examined by in situ hybridization, in vitro translation, and Northern blotting; 4. Evaluate the effects of synthetic human IAPP and synthetic fragments of IAPP on the secretion of pancreatic islet hormones (i.e. insulin, glucagon, somatostatin, and pancreatic polypeptide) using direct perfusion of rat and cat pancreas. In addition, we will evaluate rat and cat pancreas and receptor binding assays;. 5. Chemically characterize IA from degus (Octodon degus), employing extraction and purification methods used by us for cat and human IA. Amyloid samples will be purified by size exclusion and revered phase HPLC for subsequent amino acid sequencing.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK036734-05
Application #
3235227
Study Section
Metabolic Pathology Study Section (MEP)
Project Start
1986-02-01
Project End
1992-01-31
Budget Start
1990-02-01
Budget End
1991-01-31
Support Year
5
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
Schools of Veterinary Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Cornwell 3rd, G G; Johnson, K H; Westermark, P (1995) The age related amyloids: a growing family of unique biochemical substances. J Clin Pathol 48:984-9
Jordan, K; O'Brien, S J; Johnson, K H et al. (1995) Assignment of islet amyloid polypeptide (IAPP) gene to feline chromosome B4 using the polymerase chain reaction technique on feline-rodent hybrid cell lines. Vet Pathol 32:195-7
O'Brien, T D; Butler, A E; Roche, P C et al. (1994) Islet amyloid polypeptide in human insulinomas. Evidence for intracellular amyloidogenesis. Diabetes 43:329-36
O'Brien, T D; Butler, P C; Westermark, P et al. (1993) Islet amyloid polypeptide: a review of its biology and potential roles in the pathogenesis of diabetes mellitus. Vet Pathol 30:317-32
Johnson, K H; O'Brien, T D; Betsholtz, C et al. (1992) Islet amyloid polypeptide: mechanisms of amyloidogenesis in the pancreatic islets and potential roles in diabetes mellitus. Lab Invest 66:522-35
Johnson, K H; Sletten, K; Hayden, D W et al. (1992) Pulmonary vascular amyloidosis in aged dogs. A new form of spontaneously occurring amyloidosis derived from apolipoprotein AI. Am J Pathol 141:1013-9
O'Brien, T D; Westermark, P; Johnson, K H (1991) Islet amyloid polypeptide and insulin secretion from isolated perfused pancreas of fed, fasted, glucose-treated, and dexamethasone-treated rats. Diabetes 40:1701-6
Johnson, K H; O'Brien, T D; Westermark, P (1991) Newly identified pancreatic protein islet amyloid polypeptide. What is its relationship to diabetes? Diabetes 40:310-4
Galeazza, M T; O'Brien, T D; Johnson, K H et al. (1991) Islet amyloid polypeptide (IAPP) competes for two binding sites of CGRP. Peptides 12:585-91
Johnson, K H; Wernstedt, C; O'Brien, T D et al. (1991) Amyloid in the pancreatic islets of the cougar (Felis concolor) is derived from islet amyloid polypeptide (IAPP). Comp Biochem Physiol B 98:115-9

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