Progressive beta cell apoptosis is a major cause leading to a decline in beta cell mass in type 2 diabetes. While it has been discovered that mitochondrial protein Sirtuin 5 （ SIRT5 ） functions as the primary site o...Progressive beta cell apoptosis is a major cause leading to a decline in beta cell mass in type 2 diabetes. While it has been discovered that mitochondrial protein Sirtuin 5 （ SIRT5 ） functions as the primary site of oxidative metabolism and plays crucial roles in apoptosis and intracellular signaling, the contribution of SIRT5 in beta cell re- mains to be fully defined. Given the potential benefit of SIRT5 activation in cell metabolism, this study aimed to examine whether overexpression of SIRT5 in beta cells is sufficient to prevent saturated fatty acid induced impair- ment in insulin secretion and apoptosis, thus elucidating the role of SIRT5 in beta cell protection. In line with our previous study, two kinds of pancreatic beta cell lines were selected for the detection. Mouse-derived NIT-1 cells as well as human-derived PANC-1 cells were transfected with GFP-SIRT5-Ad plasmid and cell apoptosis was induced by palmitic acid （0.5 mM） , validated with TUNEL-DAPI double staining and RTCA iCelligence cell growth moni- tor system. Compared with control group, it was shown that SIRT5 overexpression could significantly reduce the quantity of apoptotic beta cells under chronic exposure to palmitic acid, accompanied with decreased Caspase 3 and Caspase 9 activities. Accordingly, cytochrome C oxidase activity in cells was also suppressed. Meanwhile, palmitic acid suppressed glucose-stimulated insulin secretion, but SIRT5 overexpression could recover the beta cell insulin secretion capacity against glucose fluctuation. Moreover, it is discovered that novel binding relationship exists be- tween SIRT5 and Bcl-XL, providing a reliable explanation for the anti-apoptosis role of SIRT5. Together, these re- sults reveal a potential role of SIRT5 in improvement of saturated fatty acid -induced beta cell dysfunction and apop- tosis. Considering the role of beta cell apoptosis in T2DM, overexpression or activation of SIRT5 may provide an e-rumpent approach as a potential target for beta cell protection. This approach might actually reverse the disease to a degree rather than just palliate glycemia.展开更多
文摘Progressive beta cell apoptosis is a major cause leading to a decline in beta cell mass in type 2 diabetes. While it has been discovered that mitochondrial protein Sirtuin 5 （ SIRT5 ） functions as the primary site of oxidative metabolism and plays crucial roles in apoptosis and intracellular signaling, the contribution of SIRT5 in beta cell re- mains to be fully defined. Given the potential benefit of SIRT5 activation in cell metabolism, this study aimed to examine whether overexpression of SIRT5 in beta cells is sufficient to prevent saturated fatty acid induced impair- ment in insulin secretion and apoptosis, thus elucidating the role of SIRT5 in beta cell protection. In line with our previous study, two kinds of pancreatic beta cell lines were selected for the detection. Mouse-derived NIT-1 cells as well as human-derived PANC-1 cells were transfected with GFP-SIRT5-Ad plasmid and cell apoptosis was induced by palmitic acid （0.5 mM） , validated with TUNEL-DAPI double staining and RTCA iCelligence cell growth moni- tor system. Compared with control group, it was shown that SIRT5 overexpression could significantly reduce the quantity of apoptotic beta cells under chronic exposure to palmitic acid, accompanied with decreased Caspase 3 and Caspase 9 activities. Accordingly, cytochrome C oxidase activity in cells was also suppressed. Meanwhile, palmitic acid suppressed glucose-stimulated insulin secretion, but SIRT5 overexpression could recover the beta cell insulin secretion capacity against glucose fluctuation. Moreover, it is discovered that novel binding relationship exists be- tween SIRT5 and Bcl-XL, providing a reliable explanation for the anti-apoptosis role of SIRT5. Together, these re- sults reveal a potential role of SIRT5 in improvement of saturated fatty acid -induced beta cell dysfunction and apop- tosis. Considering the role of beta cell apoptosis in T2DM, overexpression or activation of SIRT5 may provide an e-rumpent approach as a potential target for beta cell protection. This approach might actually reverse the disease to a degree rather than just palliate glycemia.
