Increased SUMO-2/3-ylation mediated by SENP3 degradation is protective against cadmium-induced caspase 3–dependent cytotoxicity

Increased post-translational modification of proteins by SUMO-2/3 is a cytoprotective response against cell stress induced by ischaemia and reperfusion. However, it is still unclear what other cell stressors trigger protein SUMOylation, what mechanisms enhance and maintain the enhanced SUMOylation, and if it is a general protective mediator against other cytotoxic stresses. Here, we show increased levels of SUMOylation and decreased levels of the SUMO deconjugating enzyme SENP3 in PC12 cells treated with the toxic heavy metal cadmium. In addition, SENP3 knockdown reduced cadmium- induced caspase 3 cleavage and cell death in PC12 cells, while SENP3 overexpression enhanced cell death. These results suggest that SENP3 is an important regulator of the cellular response to cadmium stress in PC12 cells. Our findings are consistent with previous reports of decreased SENP3 and increased SUMOylation in ischaemia, and imply that the regulation of SENP3 levels and subsequent changes in SUMOylation could be a cytoprotective mechanism against caspase 3-mediated cell death.