Abstract
SUMOylation is a form of post-translational modification where small ubiquitin-like modifiers (SUMO) are covalently attached to target proteins to regulate their properties. SUMOylation has been demonstrated during cell stress and implicated in cellular stress response. However, it is largely unclear if SUMOylation contributes to the pathogenesis of kidney diseases, such as acute kidney injury (AKI). Here we have demonstrated a dynamic change of protein SUMOylation in ischemic and cisplatin nephrotoxic AKI in mice. In rat kidney proximal tubular cells (RPTC), cisplatin-induced SUMOylation was diminished by two antioxidants (N-acetylcysteine and dimethylurea), supporting a role of oxidative stress in the activation of SUMOylation. In addition, SUMOylation by SUMO-2/3, but not SUMO-1, was partially suppressed by pifithrin-alpha (a pharmacological inhibitor of p53), supporting a role of p53 in SUMOylation by SUMO-2/3. We further examined the role of SUMOylation during cisplatin treatment of RPTC by using ginkgolic acid (GA), a pharmacological inhibitor of SUMOylation. Pretreatment with GA suppressed SUMOylation and importantly, GA enhanced apoptosis during cisplatin incubation. Taken together, the results demonstrate the first evidence of SUMOylation in AKI and suggest that SUMOylation may play a cytoprotective role in kidney tubular cells.