Diabetes is a huge health burden in the United States and around the world, both in decreased quality of life and in cost. This proposal addresses basic mechanisms controlling the function of pancreatic p-cells. Greater knowledge will facilitate the preservation of p-cell function and the development of safe and effective anti-diabetic therapies. The MAP kinases (MAPKs) ERK1 and ERK2 participate in the signal transduction mechanisms that integrate nutrient and hormonal inputs to the maintenance of insulin gene transcription in p-cells. The focus of this proposal is the elucidation of the functions of ERK1/2 in the normal physiology of pancreatic p-cells and in p-cell dysfunction. ERK1/2 enhance the activity of factors essential for insulin gene transcription;inhibiting ERK1/2 activity impairs insulin gene transcription. ERK1/2 are also implicated in multiple conditions in which p-cell function is impaired, including hyperglycemia and immunosuppression. High concentrations of circulating glucose that can occur in diabetes cause prolonged hyperactivationof ERK1/2 and formation of ERK1/2-sensitive transcription factor complexes associated with decreased insulin gene transcription;thus, ERK1/2 also contribute to the reduced ability of p-cells to produce insulin during prolonged hyperglycemia. We have demonstrated that at least six transcription factors that regulate insulin gene transcription are ERK1/2targets in p-cells including PDX-1, Beta2, MafA, NFAT, and C/EBP-p.
The aims are to define mechanisms by which ERK1/2 enhance transcription, to define mechanisms by which ERK1/2 inhibit transcription, and to determine the impact on p-cells of interactions of ERK1/2 with PEA-15, a protein over-expressed in type II diabetes. MafA and NFAT form an ERK1/2-dependent complex associated with increased insulin gene promoter activity. We will examine how ERK1/2 regulate their activities and explore the role of ERK1/2 in recruitment of coactivators and other proteins to transcription factor complexes. Inhibition of ERK1/2 in p-cells chronically exposed to high glucose results in a marked increase inmRNA encoding the stress-induced C/EBP homologous factor CHOP-10 (GADD153). We will define howERK1/2 inhibit expression of the CHOP-10 mRNA and explore its functions in p-cells. Exposure of p-cells to high glucose for more than 12 h inhibits insulin gene transcription in part due to induction of C/EBP-p. Blocking ERK1/2 disrupts a DNA-bound C/EBP-p complex that inhibits insulin gene transcription. Thus, we will determine mechanisms of C/EBP-p regulation by ERK1/2. PEA-15 is overexpressed in type 2 diabetes, causes hyperglycemia when expressed in mice, and impaired insulin release in MIN6 cells. PEA-15 binds directly to ERK1/2 and prevents their nuclear accumulation in fibroblasts. We will determine if overexpression of PEA-15 interferes with ERK1/2 function in p-cells and if ERK1/2 localization affects the functions of their substrates.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK055310-09
Application #
7738489
Study Section
Special Emphasis Panel (ZRG1-EMNR-G (03))
Program Officer
Appel, Michael C
Project Start
1998-09-30
Project End
2010-11-30
Budget Start
2009-12-01
Budget End
2010-11-30
Support Year
9
Fiscal Year
2010
Total Cost
$281,033
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Pharmacology
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Kalwat, Michael A; Cobb, Melanie H (2017) Mechanisms of the amplifying pathway of insulin secretion in the ? cell. Pharmacol Ther 179:17-30
Guerra, Marcy L; Kalwat, Michael A; McGlynn, Kathleen et al. (2017) Sucralose activates an ERK1/2-ribosomal protein S6 signaling axis. FEBS Open Bio 7:174-186
Kalwat, Michael A; Wichaidit, Chonlarat; Nava Garcia, Alejandra Y et al. (2016) Insulin promoter-driven Gaussia luciferase-based insulin secretion biosensor assay for discovery of ?-cell glucose-sensing pathways. ACS Sens 1:1208-1212
Kalwat, Michael A; Huang, Zhimin; Wichaidit, Chonlarat et al. (2016) Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in ?-Cells. ACS Chem Biol 11:1128-36
Wauson, Eric M; Guerra, Marcy L; Dyachok, Julia et al. (2015) Differential Regulation of ERK1/2 and mTORC1 Through T1R1/T1R3 in MIN6 Cells. Mol Endocrinol 29:1114-22
Lawrence, Michael C; Borenstein-Auerbach, Nofit; McGlynn, Kathleen et al. (2015) NFAT targets signaling molecules to gene promoters in pancreatic ?-cells. Mol Endocrinol 29:274-88
Guerra, Marcy L; Wauson, Eric M; McGlynn, Kathleen et al. (2014) Muscarinic control of MIN6 pancreatic ? cells is enhanced by impaired amino acid signaling. J Biol Chem 289:14370-9
Chamberlain, Chester E; Scheel, David W; McGlynn, Kathleen et al. (2014) Menin determines K-RAS proliferative outputs in endocrine cells. J Clin Invest 124:4093-101
Wauson, Eric M; Dbouk, Hashem A; Ghosh, Anwesha B et al. (2014) G protein-coupled receptors and the regulation of autophagy. Trends Endocrinol Metab 25:274-82
Osborne, Jihan K; Guerra, Marcy L; Gonzales, Joshua X et al. (2014) NeuroD1 mediates nicotine-induced migration and invasion via regulation of the nicotinic acetylcholine receptor subunits in a subset of neural and neuroendocrine carcinomas. Mol Biol Cell 25:1782-92

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