Supplementary Material for: Protein inhibitor of activated STAT 2 (PIAS2) protects against podocyte injury in diabetic nephropathy via inhibiting JAK2/STAT3 pathway

Background: Diabetic nephropathy (DN) is a common complication in diabetic patients, and the pathological mechanism has not been fully understood. PIAS2, as a counter regulator of the JAK2/STAT3 signaling pathway, may play a crucial role in DN. This study aims to investigate the expression of PIAS2 in high glucose-induced podocytes and the protective effect against podocyte cell injury. Methods: Human kidney podocytes were cultured under normal glucose (5.5 mM) and high glucose (30 mM) conditions. The expression of PIAS2 was detected by RT-qPCR and western blotting. Subsequently, the effects of PIAS2 overexpression in high glucose induced human podocytes were evaluated through the determination of cell viability, apoptosis, and secretion of inflammatory cytokines. Recombinant human IL-6 was used as an agonist of the JAK2/STAT3 signaling pathway to further validate the mechanism of the effects of PIAS2 in high glucose induced human podocytes. Results: High glucose treatment significantly increased the expression levels of PIAS2 in human podocytes. Overexpression of PIAS2 significantly reversed high glucose-induced human podocytes injury, evidenced by increased cell viability, reduced cell apoptosis, decreased expression of pro-apoptotic proteins Bax and cleaved-Caspase3, increased expression of the anti-apoptotic protein Bcl-2, and reduced secretion of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. Additionally, IL-6 significantly reversed the protective effects of PIAS2 on high glucose induced human podocytes. Conclusion: PIAS2 plays a protective role in DN by inhibiting JAK2/STAT3 signaling pathway to alleviate high glucose-induced podocyte injury. PIAS2 may be a potential new target in the treatment of DN.