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- Title
Role of Epac2A/Rap1 Signaling in Interplay Between Incretin and Sulfonylurea in Insulin Secretion.
- Authors
Harumi Takahashi; Tadao Shibasaki; Jae-Hyung Park; Shihomi Hidaka; Toshimasa Takahashi; Aika Ono; Dae-Kyu Song; Susumu Seino
- Abstract
Incretin-related drugs and sulfonylureas are currently used worldwide for the treatment of type 2 diabetes. We recently found that Epac2A, a cAMP binding protein having guanine nucleotide exchange activity toward Rap, is a target of both incretin and sulfonylurea. This suggests the possibility of interplay between incretin and sulfonylurea through Epac2A/Rap1 signaling in insulin secretion. In this study, we examined the combinatorial effects of incretin and various sulfonylureas on insulin secretion and activation of Epac2A/Rap1 signaling. A strong augmentation of insulin secretion by combination of GLP-1 and glibenclamide or glimepiride, which was found in Epac2A+/+ mice, was markedly reduced in Epac2A-/- mice. In contrast, the combinatorial effect of GLP-1 and gliclazide was rather mild, and the effect was not altered by Epac2A ablation. Activation of Rap1 was enhanced by the combination of an Epac-selective cAMP analog with glibenclamide or glimepiride but not gliclazide. In diet-induced obese mice, ablation of Epac2A reduced the insulin secretory response to coadministration of the GLP-1 receptor agonist liraglutide and glimepiride. These findings clarify the critical role of Epac2A/Rap1 signaling in the augmenting effect of incretin and sulfonylurea on insulin secretion and provide the basis for the effects of combination therapies of incretin-related drugs and sulfonylureas.
- Subjects
INCRETINS; GASTROINTESTINAL hormones; GASTRIC inhibitory polypeptide; SULFONYLUREAS; SULFONES
- Publication
Diabetes, 2015, Vol 64, Issue 4, p1262
- ISSN
0012-1797
- Publication type
Article
- DOI
10.2337/db14-0576