An update on the islet renin–angiotensin system

The traditional renin–angiotensin system (RAS) components have been studied extensively since the rate-limiting component of RAS, renin, was first characterized. The ongoing identification of various novel RAS components and signaling pathways continues to elaborate the complexity of this system. Regulation of RAS according to the conventional and contemporary views of its functions in various tissues under pathophysiological conditions is a main treatment strategy for many metabolic diseases. The local pancreatic RAS, first proposed to exist in pancreatic islets two decades ago, could regulate islet function and glycemic control via influences on islet cell mass, inflammation, and ion channels. Insulin secretion, the major function of pancreatic islets, is controlled by numerous factors. Among these factors and of particular interest are glucagon-like peptide-1 (GLP-1) and vitamin D, which may regulate islet function by directly binding receptors on islet beta cells. These factors may work with local RAS signaling in islets to protect and maintain islet function under diabetic and hyperglycemic conditions. In this concise review, the local islet RAS will be discussed with particular attention being paid to recent notable findings.

► Overview on contemporary notion on the renin–angiotensin system (RAS) with particular focus on the pancreatic islet RAS is critically reviewed.
► Current progress on the islet RAS and its functions are critically reviewed.
► Interaction between islet RAS and glucagon-like peptide 1 in islet cell function is discussed.
► Modulatory action of vitamin D on the pancreatic islet RAS expression and function is also discussed.