Abstract
Chronic kidney disease is defined as a progressive loss of kidney function associated with impaired recovery after acute kidney injury. Renal ischemia-reperfusion (IR) induces oxidative stress and inflammatory responses leading to severe tissue damage, where incomplete or maladaptive repair accelerates renal fibrosis and aging. To investigate the role of the purinergic P2Y2 receptor (P2Y2R) in these processes, we used P2Y2R knockout (KO) mice subjected to IR. KO mice showed severe kidney dysfunction and structural damage compared to WT mice. KO mice showed higher senescence-associated β-galactosidase expression and shorter telomere length than WT mice. Consistently, interstitial collagen accumulation and fibrogenic mediators were significantly upregulated in KO mice. Renal apoptosis and inflammation were highly elevated in KO mice. Interestingly, cell proliferation as shown by Ki-67 and PCNA expression, was increased for 3 days after IR in WT mice, whereas it maintained increased for 14 days in KO mice. Cell cycle inhibitors, p16 and p21, and regulators JunB and cyclin E were significantly increased after IR in KO mice, suggesting that cell cycle progression was impaired during recovery after IR. Proximal tubular cells treated with JunB siRNA showed a reduced expression of fibrogenic mediators and proinflammatory cytokines, consistent with the mice treated with MRS2768, a P2Y2 agonist that downregulated JunB levels. In conclusion, P2Y2R reduces kidney tissue damage after IR and repairs the tissue properly by regulating JunB-mediated signaling during the recovery process.