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- Title
Involvement of cAMP/EPAC/TRPM2 Activation in Glucose- and Incretin-Induced Insulin Secretion.
- Authors
Masashi Yosida; Katsuya Dezaki; Kunitoshi Uchida; Shiho Kodera; Lam, Nien V.; Kiyonori Ito; Rauza S. Rita; Hodaka Yamada; Kenju Shimomura; San-e Ishikawa; Hitoshi Sugawara; Masanobu Kawakami; Makoto Tominaga; Toshihiko Yada; Masafumi Kakei
- Abstract
In pancreatic β-cells, closure of the ATP-sensitive K+ (KATP) 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 KATP 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.
- Subjects
DIABETES; ADENOSINE triphosphate; CATIONS; EXENDINS; INSULIN; BLOOD sugar
- Publication
Diabetes, 2014, Vol 63, Issue 10, p3394
- ISSN
0012-1797
- Publication type
Article
- DOI
10.2337/db13-1868