Sustained hyperglycemia from diabetes causes catastrophic damage to many organs and tissues. An emerging point of view is focused on the rise in blood glucose following a meal. These blood glucose levels can be very high, and the peak concentration is more predictive of end organ damage in diabetes than the more commonly measured fasting glucose levels. Complex physiological mechanisms exist to specifically handle the post-meal glucose load, and a breakdown in these mechanisms causes diabetes. The long term goal of this study is to understand the post-meal regulation of glucose stimulated insulin secretion from pancreatic beta-islet cells. Glucokinase (GK) sets the rate of insulin secretion, and acute post-translational regulation of GK through interaction with nitric oxide synthase (NOS) and reaction with nitric oxide have recently been proposed. However, the mechanisms that control GK interaction with NOS and the physiological role of GK regulation by nitric oxide are not understood.
Specific Aim 1 will quantify the effect of nitrosylation on GK kinetics.
Specific Aim 2 will use a domain swapping strategy to identify the sequence elements in GK essential to complex formation with NOS.
Specific Aim 3 will identify cellular mechanisms used to control GK activation on secretory granules and Specific Aim 4 will test the hypothesis that regulation of GK by NOS is utilized for positive regulation of glucose-stimulated insulin secretion by a known post-meal incretin hormone, glucagon-like peptide 1. These studies will be accomplished using biochemical methods and fluorescence imaging techniques. This research will further understanding of the mechanisms that regulate nutrient-stimulated insulin secretion and are particularly relevant to understanding the pathogenesis of diabetes, since dysfunctional insulin secretion is one of the central abnormalities associated with type 2 diabetes.

Public Health Relevance

Insulin is secreted from the pancreas in response to rising blood glucose levels, and the strength of the secretory response is controlled by hormones. This study will gather information relating to the mechanisms that hormones use to control the rate of insulin secretion, and determine the extent that dysfunction of a particular mechanism contributes to a specific genetic type of diabetes.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Cellular Aspects of Diabetes and Obesity Study Section (CADO)
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Appel, Michael C
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University of Maryland Baltimore
Schools of Medicine
United States
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Mauban, Joseph R H; Fairfax, Seth T; Rizzo, Mark A et al. (2014) A method for noninvasive longitudinal measurements of [Ca2+] in arterioles of hypertensive optical biosensor mice. Am J Physiol Heart Circ Physiol 307:H173-81
Haataja, Leena; Snapp, Erik; Wright, Jordan et al. (2013) Proinsulin intermolecular interactions during secretory trafficking in pancreatic ? cells. J Biol Chem 288:1896-906
Ding, Shi-Ying; Nkobena, Andongfac; Kraft, Catherine A et al. (2011) Glucagon-like peptide 1 stimulates post-translational activation of glucokinase in pancreatic beta cells. J Biol Chem 286:16768-74
Markwardt, Michele L; Kremers, Gert-Jan; Kraft, Catherine A et al. (2011) An improved cerulean fluorescent protein with enhanced brightness and reduced reversible photoswitching. PLoS One 6:e17896
Ding, Shi-Ying; Tribble, Nicholas D; Kraft, Catherine A et al. (2010) Naturally occurring glucokinase mutations are associated with defects in posttranslational S-nitrosylation. Mol Endocrinol 24:171-7