| First Author | Gustavsson N | Year | 2011 |
| Journal | Diabetologia | Volume | 54 |
| Issue | 7 | Pages | 1824-30 |
| PubMed ID | 21424898 | Mgi Jnum | J:170316 |
| Mgi Id | MGI:4946315 | Doi | 10.1007/s00125-011-2119-3 |
| Citation | Gustavsson N, et al. (2011) Synaptotagmin-7 as a positive regulator of glucose-induced glucagon-like peptide-1 secretion in mice. Diabetologia 54(7):1824-30 |
| abstractText | AIMS/HYPOTHESIS: Glucagon-like peptide-1 (GLP-1), a hormone with potent antihyperglycaemic effects, is produced and secreted from highly specialised gut endocrine L-cells. It regulates glucose homeostasis by promoting glucose-dependent insulin secretion, suppressing glucagon secretion and enhancing insulin sensitivity. Similar to islet alpha and beta cells, L-cells are electrically excitable, and express calcium channels and ATP-sensitive potassium channels. GLP-1 is also stored in secretory granules, the exocytosis of which is triggered by increased intracellular calcium levels. Although the calcium dependence of GLP-1 granule exocytosis is well established, the identities of calcium-sensing proteins in GLP-1 secretion remain elusive. Here we tested whether synaptotagmin-7, a calcium sensor in pancreatic alpha and beta cells, regulates GLP-1 secretion. METHODS: We studied GLP-1 secretion using synaptotagmin-7 knockout (KO) mice and GLUTag cells with lentiviral-mediated synaptotagmin-7 silencing. RESULTS: We found that synaptotagmin-7 was co-localised with GLP-1 in intestinal L-cells. GLP-1 secretion was impaired in synaptotagmin-7 KO mice when they were challenged by glucose ingestion. Lentiviral knockdown (KD) of synaptotagmin-7 in GLUTag cells led to similar reductions in GLP-1 secretion, as determined by biochemical assays and by membrane capacitance measurements. Calcium response was not altered in synaptotagmin-7 KD cells. CONCLUSIONS/INTERPRETATION: These results demonstrate that synaptotagmin-7 functions as a positive regulator of GLP-1 secretion in intestinal L-cells and GLUTag cells, consistent with its proposed role as a calcium sensor in GLP-1 secretion. |
