Nitric oxide (NO) may block apoptosis by inhibiting caspases via S-nitrosylation of cysteines. Here, we investigated whether effector caspases might cleave and thereby inhibit endothelial nitric oxide synthase (eNOS). Exposure of eNOS-transfected COS-7 cells and bovine aortic endothelial cells to staurosporine resulted in significant loss of 135-kDa eNOS protein and activity, and appearance of a 60-kDa eNOS fragment; effects were inhibited by the general caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp[OMe]-fluoromethyl ketone (zVAD-fmk). In eNOS-transfected COS-7 cells, staurosporine-induced activation of caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage coincided with increased eNOS degradation and decreased activity. Loss of eNOS activity was greater than the degree of proteolysis. Incubation of immunoprecipitated eNOS with caspase-3, caspase-6 or caspase-7 resulted in eNOS cleavage. Staurosporine, a general protein kinase inhibitor, also reduced phosphorylation and decreased calmodulin binding, an effect that may explain the reduction in activity. eNOS, therefore, is both an inhibitor of apoptosis and a target of apoptosis-associated proteolysis.
Tesauro, M., Thompson, W., Moss, J. (2006). Effect of staurosporine-induced apoptosis on endothelial nitric oxide synthase in transfected COS-7 cells and primary endothelial cells. CELL DEATH AND DIFFERENTIATION, 13(4), 597-606 [10.1038/sj.cdd.4401770].
Effect of staurosporine-induced apoptosis on endothelial nitric oxide synthase in transfected COS-7 cells and primary endothelial cells
TESAURO, MANFREDI;
2006-01-01
Abstract
Nitric oxide (NO) may block apoptosis by inhibiting caspases via S-nitrosylation of cysteines. Here, we investigated whether effector caspases might cleave and thereby inhibit endothelial nitric oxide synthase (eNOS). Exposure of eNOS-transfected COS-7 cells and bovine aortic endothelial cells to staurosporine resulted in significant loss of 135-kDa eNOS protein and activity, and appearance of a 60-kDa eNOS fragment; effects were inhibited by the general caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp[OMe]-fluoromethyl ketone (zVAD-fmk). In eNOS-transfected COS-7 cells, staurosporine-induced activation of caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage coincided with increased eNOS degradation and decreased activity. Loss of eNOS activity was greater than the degree of proteolysis. Incubation of immunoprecipitated eNOS with caspase-3, caspase-6 or caspase-7 resulted in eNOS cleavage. Staurosporine, a general protein kinase inhibitor, also reduced phosphorylation and decreased calmodulin binding, an effect that may explain the reduction in activity. eNOS, therefore, is both an inhibitor of apoptosis and a target of apoptosis-associated proteolysis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
