Referenced in: none

Automatically associated channels: TRP , TRPM , TRPM2

Title: Involvement of cAMP/EPAC/TRPM2 activation in glucose- and incretin-induced insulin secretion.

Authors: Masashi Yosida, Katsuya Dezaki, Kunitoshi Uchida, Shiho Kodera, Nien V Lam, Kiyonori Ito, Rauza S Rita, Hodaka Yamada, Kenju Shimomura, San-E Ishikawa, Hitoshi Sugawara, Masanobu Kawakami, Makoto Tominaga, Toshihiko Yada, Masafumi Kakei

Journal, date & volume: Diabetes, 2014 Oct , 63, 3394-403

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24824430

Abstract
In pancreatic β-cells, closure of the ATP-sensitive K(+) (K(ATP)) channel is an initial process triggering glucose-stimulated insulin secretion. In addition, constitutive opening of background nonselective cation channels (NSCCs) is essentially required to effectively evoke depolarization as a consequence of K(ATP) channel closure. Thus, it is hypothesized that further opening of NSCC facilitates membrane excitability. We identified a class of NSCC that was activated by exendin (ex)-4, GLP-1, and its analog liraglutide at picomolar levels. This NSCC was also activated by increasing the glucose concentration. NSCC activation by glucose and GLP-1 was a consequence of the activated cAMP/EPAC-mediated pathway and was attenuated in TRPM2-deficient mice. The NSCC was not activated by protein kinase A (PKA) activators and was activated by ex-4 in the presence of PKA inhibitors. These results suggest that glucose- and incretin-activated NSCC (TRPM2) works in concert with closure of the KATP channel to effectively induce membrane depolarization to initiate insulin secretion. The current study reveals a new mechanism for regulating electrical excitability in β-cells and for mediating the action of glucose and incretin to evoke insulin secretion, thereby providing an innovative target for the treatment of type 2 diabetes.