Nitric oxide induces apoptosis via Ca2+-dependent processes in the pancreatic beta-cell line MIN6.

An excessive production of nitric oxide (NO) in response to cytokines has been shown to be the major cause of the destruction of islet beta-cells associated with type 1 (insulin-dependent) diabetes mellitus. The NO-induced beta-cell death is the typical apoptosis. In the present study, we show evidence that supports a tight link between NO, Ca2+, protease and apoptosis in beta-cells. Three different NO donors, SNAP, NOR3 and NOC7, induced apoptosis in a beta-cell line, MIN6 cells, in a concentration-dependent manner. SNAP at 200 microM increased cytosolic Ca2+ concentration ([Ca2+]i) and induced apoptosis. The SNAP-induced apoptosis was blocked by a Ca2+ chelator, BAPTA-AM, and by an inhibitor of a Ca2+-dependent protease, calpain. In conclusion, an excessive NO production induces apoptosis, wherein an increase in [Ca2+]i and resultant activation of calpain play a key role.