This application describes a program of research in peptide hormone endocrinology that spans both considerations of hormone biogenesis, action and degradation and the disciplines of biochemistry, chemistry, cell biology and physiology. Emphasis in this application is placed on the bioactive peptides of the endocrine pancreas (insulin, glucagon, somatostatin and pancreatic polypeptide) and on the precedents that may be gleaned by the study of these hormones in concern. While several different projects are described, they are joined by a common focus in chemical structure, biochemical specificity and molecular interactions.
Specific aims i nclude (a) analysis of the specificity of prohormone conversion at paired and single dibasic amino acid conversion sites by model enzymes and tissue proteases, (b) determination of the structures of abnormal products of peptide hormone genes and of the causes of hyper(pro)insulinemia in selected cases where insulin gene structure appears to be normal, (c) analysis of detailed structure-function relationships and conformational changes involved in the combination of insulin with its receptor, (d) examination of the kintic and chemical heterogeneity of insulin receptors expressed in hepatic tissue, (e) determination of the molecular basis of multiple glucagon receptor populations on hepatocytes and hepatic membranes, (f) analysis of the causes and consequences of glucagon antagonism and desensitization in isolated hepatocytes, (g) determination of the biochemical basis for multiple ligand-receptor states that occur subsequent to peptide hormone-receptor interactions, (h) evaluation of the intracellular sites and biochemical correlates of peptide hormone metabolism by target tissues, (i) determintion of the existence of peptide hormone metabolites in the circulation in man, and (j) analysis of potential regulatory mechanisms that modulate ligand-receptor interactions and peptide hormone degradation in hepatic tissue. Methods involve isolated cell and membrane incubation, tissue extraction for identification of peptides and modifying enzymes, kinetic measurements of hormone-receptor interactions, biochemical and chemical analysis of detergent-solubilized receptors, radiolabeling of peptide hormones and their analogs, peptide and protein purification and analysis by molecular sieve and reverse-phase chromatography and by other methods of protein chemistry, and chemical synthesis of peptides and peptide analogs for use as receptor probes. While these studies relate most directly to investigation of diabetes and other diseases of the endocrine pancreas, the long-term objective relates more broadly to understanding how endocrine regulations leads to metabolic homeostasis and how variations in control can lead to inappropriate metabolic regulation in man.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DK018347-19
Application #
3483258
Study Section
Special Emphasis Panel (NSS)
Project Start
1977-08-01
Project End
1994-07-31
Budget Start
1992-08-01
Budget End
1993-07-31
Support Year
19
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Chicago
Department
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
Nakagawa, S H; Tager, H S; Steiner, D F (2000) Mutational analysis of invariant valine B12 in insulin: implications for receptor binding. Biochemistry 39:15826-35
Pittman 4th, I; Tager, H S (1995) A spectroscopic investigation of the conformational dynamics of insulin in solution. Biochemistry 34:10578-90
Nakagawa, S H; Johansen, N L; Madsen, K et al. (1993) Implications of replacing peptide bonds in the COOH-terminal B chain domain of insulin by the psi (CH2-NH) linker. Int J Pept Protein Res 42:578-84
Nakagawa, S H; Tager, H S (1993) Importance of main-chain flexibility and the insulin fold in insulin-receptor interactions. Biochemistry 32:7237-43
Post, S R; Rubinstein, P G; Tager, H S (1993) Mechanism of action of des-His1-[Glu9]glucagon amide, a peptide antagonist of the glucagon receptor system. Proc Natl Acad Sci U S A 90:1662-6
Nakagawa, S H; Tager, H S (1992) Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions. Biochemistry 31:3204-14
Post, S R; Miyazaki, H; Tager, H S (1992) Identification of a Mg(2+)- and guanyl nucleotide-dependent glucagon receptor cycle by use of permeabilized canine hepatocytes. J Biol Chem 267:25776-85
Yamada, Y; Post, S R; Wang, K et al. (1992) Cloning and functional characterization of a family of human and mouse somatostatin receptors expressed in brain, gastrointestinal tract, and kidney. Proc Natl Acad Sci U S A 89:251-5
Nakagawa, S H; Tager, H S (1991) Implications of invariant residue LeuB6 in insulin-receptor interactions. J Biol Chem 266:11502-9
Mirmira, R G; Tager, H S (1991) Disposition of the phenylalanine B25 side chain during insulin-receptor and insulin-insulin interactions. Biochemistry 30:8222-9

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