| Pancreatic alpha cells secrete glucagon to increase blood glucose during hypoglycemia. Currently, the mechanisms that initiate glucagon secretion are not well understood. This study investigates the expression of pro-opiomelanocortin (POMC), a potent regulator of glucagon secretion, in alpha cells.;Insulin tolerance tests in mice lacking the POMC gene showed a correlation between alpha MSH, and glucagon secretion from alpha cells (Hochgeschwender et al. 2003). Results from a previous study showed that the POMC product, melanocortin alpha-MSH, acts through a melanocortin receptor 4 (MC4R) at the surface of the alpha cells to trigger the release of glucagon [Angleson, unpublished data, Lumsden MS thesis 2008]. The results of the current study indicate that POMC is expressed in pancreatic alpha cells.;Analysis through quantitative PCR, Western blot, as well as a combination of fluorescent techniques was used to investigate the expression of POMC in mouse pancreatic tissue and dispersed islets cells, as well as an alpha cell line. POMC was found to be expressed in alpha cells, not in beta cells of the pancreas. The results suggest a mechanism for positive autocrine feedback of alpha cells. |
