| First Author | Brar GS | Year | 2017 |
| Journal | Diabetes | Volume | 66 |
| Issue | 8 | Pages | 2201-2212 |
| PubMed ID | 28559246 | Mgi Jnum | J:249550 |
| Mgi Id | MGI:5923097 | Doi | 10.2337/db16-1318 |
| Citation | Brar GS, et al. (2017) Neprilysin Is Required for Angiotensin-(1-7)'s Ability to Enhance Insulin Secretion via Its Proteolytic Activity to Generate Angiotensin-(1-2). Diabetes 66(8):2201-2212 |
| abstractText | Recent work has renewed interest in therapies targeting the renin-angiotensin system (RAS) to improve beta-cell function in type 2 diabetes. Studies show that generation of angiotensin-(1-7) by ACE2 and its binding to the Mas receptor (MasR) improves glucose homeostasis, partly by enhancing glucose-stimulated insulin secretion (GSIS). Thus, islet ACE2 upregulation is viewed as a desirable therapeutic goal. Here, we show that, although endogenous islet ACE2 expression is sparse, its inhibition abrogates angiotensin-(1-7)-mediated GSIS. However, a more widely expressed islet peptidase, neprilysin, degrades angiotensin-(1-7) into several peptides. In neprilysin-deficient mouse islets, angiotensin-(1-7) and neprilysin-derived degradation products angiotensin-(1-4), angiotensin-(5-7), and angiotensin-(3-4) failed to enhance GSIS. Conversely, angiotensin-(1-2) enhanced GSIS in both neprilysin-deficient and wild-type islets. Rather than mediating this effect via activation of the G-protein-coupled receptor (GPCR) MasR, angiotensin-(1-2) was found to signal via another GPCR, namely GPCR family C group 6 member A (GPRC6A). In conclusion, in islets, intact angiotensin-(1-7) is not the primary mediator of beneficial effects ascribed to the ACE2/angiotensin-(1-7)/MasR axis. Our findings warrant caution for the concurrent use of angiotensin-(1-7) compounds and neprilysin inhibitors as therapies for diabetes. |
