2190-P: Sex-Based Differences in Nr4a1 Beta-Cell Activity

Abstract

The orphan nuclear hormone receptor Nr4a1 plays a critical role in maintaining and expanding functional beta cell mass. Overexpression of Nr4a1 is sufficient to induce beta cell proliferation in primary beta cells by upregulating cell cycle progression, while maintaining glucose-stimulated insulin secretion. Full body deletion of Nr4a1 results in decreased beta cell mass, while resulting in modified fuel utilization in liver and muscle. Knock down of Nr4a1 decreases glycolytic and TCA cycle gene expression, impairs mitochondrial respiration, decreases cellular ATP levels, and ultimately decreases glucose-stimulated insulin secretion. While Nr4a1 is currently considered an orphaned nuclear hormone receptor, recent findings suggest that unsaturated fatty acids may function as a ligand, and that exposure to these fatty acid’s changes Nr4a1 affinity for promoters of genes involved in fuel utilization. To determine the effect of Nr4a1 presence of absence in the beta cell, and the effect of fatty acid exposure, we developed a beta cell specific, inducible, Nr4a1 knock out mouse. Male and female mice, deficient for Nr4a1 beginning at 3 months of age, were fed a normal chow or high fat diet for an additional four months. Here we present data demonstrating a sex specific difference in phenotype. Male mice demonstrated improved glucose tolerance at four months of feeding, while female mice demonstrated impaired glucose tolerance as early as one month of feeding. Here we present data regarding differences in beta cell mass, glucose stimulated insulin secretion, as well as Nr4a1 DNA binding from in islets from male and female mice exposed to unsaturated and saturated fatty acids. These data begin to demonstrate the role of Nr4a1 in controlling gene expression as a function of nutrient exposure, as well as sex-based differences in Nr4a1 activity. Disclosure J.S. Tessem: None. J. Herring: None. C.J. Smith: None. M.C. Austin: None. A.G. Wynn: None. Funding American Diabetes Association (1-17-IBS-101 to J.S.T.)