Retinoic acid receptor signaling is required to maintain glucose-stimulated insulin secretion and β-cell mass

Retinoic acid signaling is required for maintaining a range of cellular processes, including cell differentiation, proliferation, and apoptosis. We investigated the actions of all-trans-retinoic acid (atRA) signaling in pancreatic beta-cells of adult mice. atRA signaling was ablated in beta-cells by overexpressing a dominant-negative retinoic acid receptor (RAR)-alpha mutant (RARdn) using an inducible Cre-Lox system under the control of the pancreas duodenal homeobox gene promoter. Our studies establish that hypomorphism for RAR in beta-cells leads to an age-dependent decrease in plasma insulin in the fed state and in response to a glucose challenge. Glucose-stimulated insulin secretion was also impaired in islets isolated from mice expressing RARdn. Among genes that are atRA responsive, Glut2 and Gck mRNA levels were decreased in isolated islets from RARdn-expressing mice. Histologic analyses of RARdn-expressing pancreata revealed a decrease in beta-cell mass and insulin per beta-cell 1 mo after induction of the RARdn. Our results indicate that atRA signaling mediated by RARs is required in the adult pancreas for maintaining both beta-cell function and mass, and provide insights into molecular mechanisms underlying these actions.-Brun, P.-J., Grijalva, A., Rausch, R., Watson, E., Yuen, J. J., Das, B. C., Shudo, K., Kagechika, H., Leibel, R. L., Blaner, W. S. Retinoic acid receptor signaling is required to maintain glucose-stimulated insulin secretion and b-cell mass.