ATP-sensitive potassium (KATP) channels in pancreatic b-cells couple blood glucose concentrations to membrane excitability thus control insulin secretion. The b-cell KATP channel is a complex of four sulfonylurea receptor 1 and four inwardly rectifying potassium channel Kir6.2 subunits. Mutations in the channel genes that lead to loss of channel function have been known for quite some time to underlie the insulin secretion disease congenital hyperinsulinism. More recently, gain-of-function channel mutations have been discovered as a major cause of neonatal diabetes. The long-term goal of our research is to understand regulation of b-cell KATP channels, how this regulation is perturbed by channel mutations to cause disease and how we may manipulate channel regulation to combat insulin secretion disease. Work supported by this grant to date has identified several novel mechanisms by which channel mutations cause abnormal insulin secretion. Among these, defective channel biogenesis and trafficking that results in reduced surface channel expression levels is the most prevalent in mutations associated with congenital hyperinsulinism. Interestingly, our recent work found many neonatal diabetes mutations also affect channel biogenesis and surface expression. Of significance, we have identified a group of mutations whose trafficking defects could be corrected pharmacologically by sulfonylureas, drugs commonly used to treat type II diabetes. These findings underscore the importance of channel biogenesis and trafficking, which in turn control surface channel expression, in b-cell function and the potential of manipulating these cellular events to treat insulin secretion disease. In this renewal application, we will build up on these findings and further investigate the biogenesis and trafficking regulation of KATP channels in b-cells. Using a combination of molecular, biochemical, cell biological and electrophysiological approaches we will (1) delineate the biogenesis and trafficking pathways of KATP channels in b-cells, (2) determine how channel mutations alter channel expression and gating to cause b-cell dysfunction and disease, and (3) elucidate the mechanism by which sulfonylureas rescue channel biogenesis/trafficking defects and assess the utility of sulfonylureas in restoring mutant channel expression and function in b-cells. The proposed studies will better our understanding of how regulation of KATP channel trafficking contributes to regulation of insulin secretion. This information is critical for our long-term goal of integrating all aspects of KATP channel regulation to fully understand the role of these channels in b-cell function under physiological and pathological conditions.

Public Health Relevance

Abnormal insulin secretion results in life-threatening diseases such as diabetes and hyperinsulinism. We propose to study how mutations in the KATP channel, a key molecule involved in regulation of insulin secretion, affect channel properties to cause disease and how we can correct channel defects caused by mutations. These studies are highly relevant to human health and may lead to novel therapeutic strategies for these devastating diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK057699-10
Application #
7787427
Study Section
Special Emphasis Panel (ZRG1-EMNR-A (03))
Program Officer
Appel, Michael C
Project Start
2000-04-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
10
Fiscal Year
2010
Total Cost
$312,543
Indirect Cost
Name
Oregon Health and Science University
Department
Neurosciences
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Wu, Yi; Fortin, Dale A; Cochrane, Veronica A et al. (2017) NMDA receptors mediate leptin signaling and regulate potassium channel trafficking in pancreatic ?-cells. J Biol Chem 292:15512-15524
Shyng, Show-Ling (2017) Targeting the Gut Microbiota-FXR Signaling Axis for Glycemic Control: Does a Dietary Supplement Work Magic? Diabetes 66:571-573
Martin, Gregory M; Rex, Emily A; Devaraneni, Prasanna et al. (2016) Pharmacological Correction of Trafficking Defects in ATP-sensitive Potassium Channels Caused by Sulfonylurea Receptor 1 Mutations. J Biol Chem 291:21971-21983
Devaraneni, Prasanna K; Martin, Gregory M; Olson, Erik M et al. (2015) Structurally distinct ligands rescue biogenesis defects of the KATP channel complex via a converging mechanism. J Biol Chem 290:7980-91
Saint-Martin, C; Zhou, Q; Martin, G M et al. (2015) Monoallelic ABCC8 mutations are a common cause of diazoxide-unresponsive diffuse form of congenital hyperinsulinism. Clin Genet 87:448-54
Wu, Yi; Shyng, Show-Ling; Chen, Pei-Chun (2015) Concerted Trafficking Regulation of Kv2.1 and KATP Channels by Leptin in Pancreatic ?-Cells. J Biol Chem 290:29676-90
Zhou, Qing; Chen, Pei-Chun; Devaraneni, Prasanna K et al. (2014) Carbamazepine inhibits ATP-sensitive potassium channel activity by disrupting channel response to MgADP. Channels (Austin) 8:376-82
Zhou, Qing; Chen, Pei-Chun; Devaraneni, Prasanna K et al. (2014) Carbamazepine inhibits ATP-sensitive potassium channel activity by disrupting channel response to MgADP. Channels (Austin) 8:376-82
Faletra, Flavio; Snider, Kara; Shyng, Show-Ling et al. (2013) Co-inheritance of two ABCC8 mutations causing an unresponsive congenital hyperinsulinism: clinical and functional characterization of two novel ABCC8 mutations. Gene 516:122-5
Snider, K E; Becker, S; Boyajian, L et al. (2013) Genotype and phenotype correlations in 417 children with congenital hyperinsulinism. J Clin Endocrinol Metab 98:E355-63

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