| First Author | Georgiadou E | Year | 2022 |
| Journal | Diabetes | Volume | 71 |
| Issue | 7 | Pages | 1472-1489 |
| PubMed ID | 35472764 | Mgi Jnum | J:326794 |
| Mgi Id | MGI:7314376 | Doi | 10.2337/db21-0800 |
| Citation | Georgiadou E, et al. (2022) Mitofusins Mfn1 and Mfn2 Are Required to Preserve Glucose- but Not Incretin-Stimulated beta-Cell Connectivity and Insulin Secretion. Diabetes 71(7):1472-1489 |
| abstractText | Mitochondrial glucose metabolism is essential for stimulated insulin release from pancreatic beta-cells. Whether mitofusin gene expression, and hence, mitochondrial network integrity, is important for glucose or incretin signaling has not previously been explored. Here, we generated mice with beta-cell-selective, adult-restricted deletion knock-out (dKO) of the mitofusin genes Mfn1 and Mfn2 (betaMfn1/2 dKO). betaMfn1/2-dKO mice displayed elevated fed and fasted glycemia and a more than fivefold decrease in plasma insulin. Mitochondrial length, glucose-induced polarization, ATP synthesis, and cytosolic and mitochondrial Ca2+ increases were all reduced in dKO islets. In contrast, oral glucose tolerance was more modestly affected in betaMfn1/2-dKO mice, and glucagon-like peptide 1 or glucose-dependent insulinotropic peptide receptor agonists largely corrected defective glucose-stimulated insulin secretion through enhanced EPAC-dependent signaling. Correspondingly, cAMP increases in the cytosol, as measured with an Epac-camps-based sensor, were exaggerated in dKO mice. Mitochondrial fusion and fission cycles are thus essential in the beta-cell to maintain normal glucose, but not incretin, sensing. These findings broaden our understanding of the roles of mitofusins in beta-cells, the potential contributions of altered mitochondrial dynamics to diabetes development, and the impact of incretins on this process. |
