Annexin A2 alleviates renal ischemia/reperfusion injury via regulating membranal ESCRT-III to suppress necroptosis of tubular epithelial cells

Renal functional impairment, resulting from nephron-sparing surgery (NSS), is mainly caused by ischemia-reperfusion injury (IRI) and majorly affects kidney function. Necroptosis plays an important role in renal IRI, however its mechanism remains unknown. We used Anxa2 knockout mice to investigate the role and mechanism of Anxa2 in renal IRI. Moreover, We further explored its underlying molecular mechanism by co-immunoprecipitation combined with mass spectrometry (IP-MS). Our results showed that Anxa2 accumulated significantly at the apical membrane of renal tubular epithelial cells of the medulla after renal IRI. In Anxa2 knockout mice, injury was significantly increased in the medulla rather than in the cortex, and necroptosis was found to be aggravated in medullary tubular epithelial cells accompanied by increased neutrophil infiltration in the injured area. Mechanistically, Anxa2 can specifically bind to Chmp2A after renal IR, an important component protein of endosomal sorting complex required for transport III (ESCRT-III). In knockout mice, membranal Chmp2A content in the renal medulla was significantly decreased, but not cytoplasmic Chmp2A. The other component proteins of the ESCRT-III complex, such as Chmp2B, Chmp3, Chmp4B and Vps4B, followed the same trend as Chmp2A. We also found that Cxcl1 and Cxcl2 , which are specific neutrophil chemokines, were significantly upregulated without Anxa2 expression both in vivo and in vitro. Moreover, Necrostatin 1 (Nec1), a specific necroptosis inhibitor, rescued the Anxa2 deficiency-induced necroptosis, neutrophil infiltration and IRI. This study demonstrates that Anxa2 can inhibit necroptosis of renal medullary tubular epithelial cells, reduce local neutrophil infiltration and inflammatory factors, and protect against the renal IRI. More importantly, we describe the molecular mechanism by which Anxa2 inhibits necroptosis by regulating ESCRT-III. Our study clarified the role and mechanism of Anxa2 function in renal IRI, providing new clinical strategies for its prevention and treatment.