Type 2 diabetes can lead to serious health complications including stroke and blindness. The disease develops when the body is unable to produce a sufficient amount of insulin. Insulin is a hormone produced by β-cells in the pancreas in response to spikes in blood sugar. It works by lowering blood sugar to maintain it within a healthy range. Although it has been known for years that pancreatic β-cells produce insulin, the molecular mechanisms underpinning this process and how they malfunction in diabetes remain elusive.
Recently, Dr. Herbert Gaisano, a Senior Scientist at TGHRI, identified a protein that plays an important role in the secretion of insulin from pancreatic β-cells.
Given that the protein Synaptotagmin-7 (Syt-7) has been implicated in insulin production in mice, Dr. Gaisano and his colleagues examined its role in humans. The researchers found an abundance of Syt-7 protein in pancreatic β-cells obtained from healthy humans. Moreover, they demonstrated that depleting the Syt-7 protein in these cells lowered the amount of insulin that they produced and that Syt-7 binds directly to SNARE proteins, which are instrumental in the secretion of insulin from β-cells.
Taken together, these results suggest that Syt-7 is needed for the release of sufficient quantities of insulin to maintain healthy blood sugar. Given that lowered levels of Syt-7 have been found in type 2 diabetes, restoring the protein’s levels in pancreatic β-cells, alone or in conjunction with other diabetes drugs, may represent a new therapeutic strategy to treat the condition.
This work was supported by the Canadian Institutes of Health Research, the Banting & Best Diabetes Centre, the Canada Foundation for Innovation and the Toronto General & Western Hospital Foundation.
Synaptotagmin-7 Functions to Replenish Insulin Granules for Exocytosis in Human Islet β-Cells. Dolai S, Xie L, Zhu D, Liang T, Qin T, Xie H, Kang Y, Chapman ER, Gaisano HY. Diabetes. 2016 July. doi: 10.2337/db15-1436. [Pubmed abstract].