| First Author | Kwan EP | Year | 2006 |
| Journal | Diabetes | Volume | 55 |
| Issue | 5 | Pages | 1421-9 |
| PubMed ID | 16644700 | Mgi Jnum | J:108689 |
| Mgi Id | MGI:3624511 | Doi | 10.2337/db05-1263 |
| Citation | Kwan EP, et al. (2006) Munc13-1 deficiency reduces insulin secretion and causes abnormal glucose tolerance. Diabetes 55(5):1421-9 |
| abstractText | Munc13-1 is a diacylglycerol (DAG) receptor that is essential for synaptic vesicle priming. We recently showed that Munc13-1 is expressed in rodent and human islet beta-cells and that its levels are reduced in islets of type 2 diabetic humans and rat models, suggesting that Munc13-1 deficiency contributes to the abnormal insulin secretion in diabetes. To unequivocally demonstrate the role of Munc13-1 in insulin secretion, we studied heterozygous Munc13-1 knockout mice (+/-), which exhibited elevated glucose levels during intraperitoneal glucose tolerance tests with corresponding lower serum insulin levels. Munc13-1(+/-) mice exhibited normal insulin tolerance, indicating that a primary islet beta-cell secretory defect is the major cause of their hyperglycemia. Consistently, glucose-stimulated insulin secretion was reduced 50% in isolated Munc13-1(+/-) islets and was only partially rescued by phorbol ester potentiation. The corresponding alterations were minor in mice expressing one allele of a Munc13-1 mutant variant, which does not bind DAG (H567K/+). Capacitance measurements of Munc13-1(+/-) and Munc13-1(H567k/+) islet beta-cells revealed defects in granule priming, including the initial size and refilling of the releasable pools, which become accentuated by phorbol ester potentiation. We conclude that Munc13-1 plays an important role in glucose-stimulated insulin secretion and that Munc13-1 deficiency in the pancreatic islets as occurs in diabetes can reduce insulin secretion sufficient to cause abnormal glucose homeostasis. |
