MeCP2 Promotes Cisplatin-Induced AKI Through Epigenetic Regulation of IRF8

Background: Emerging evidence suggests that epigenetic regulation like DNA methylation plays an important part in the process of acute kidney injury (AKI), but the mechanism remains largely elusive. Methyl-CpG binding protein 2 (MeCP2) is an epigenetic regulator which binds to methylated cytosines and functions as gene transcriptional inhibitor or activator. The role of MeCP2 was examined most notably in brain development, while the involvement of MeCP2 in renal disease remains unknown. Methods: Twenty male C57 mice were randomly grouped into control, cisplatin-1d, cisplatin-2d and cisplatin-4d according to the time of execution after cisplatin intraperitoneal injection. HK-2 cells were exposed to cisplatin at 20uM for variable incubation time. Renal histopathological changes were observed by hematoxylin eosin staining (HE). Renal tubular injury marker NGAL and KIM-1 were measured by enzyme linked immunosorbent assay (ELISA). HK-2 cells were transfected by siRNA to knockdown MeCP2 expression. The expression of MeCP2, Irf8 and caspase3 were respectively detected by qPCR, western blot and immunohistochemistry. ChIP was used to analyze the binding of MeCP2 to the interferon regulatory factor 8 (Irf8) gene. Results: We found consistent expression of MeCP2 in renal cortical tubules of SD rat, WKY rat, and C57 mouse. Compared with the sham group, cisplatin-treated mice kidney showed significant upregulation of MeCP2 in proximal tubules in both protein and mRNA level, accompanied by severe renal histology changes and the upregulation of NGAL and KIM-1. In vitro, MeCP2 was also induced in cultured proximal tubular cells by cisplatin treatment. Interestingly, knocking down MeCP2 alleviated caspase-3-dependent tubular cell apoptosis but enhanced cell autophagy induced by cisplatin. Furthermore, a pro-apoptotic gene interferon regulatory factor 8 (IRF8) was found upregulated in tubular cells by cisplatin in vivo and in vitro. Importantly, we demonstrated that MeCP2 upregulated Irf8 expression by directly binding to its gene promoter. Conclusion: Taken together, our data demonstrated that MeCP2 promoted cisplatin-induced renal tubular damage by facilitating apoptotic process and inhibiting autophagy activity. The epigenetic regulation of pro-apoptotic gene IRF8 by MeCP2 may be the possible mechanism implicated in the pathophysiological process of cisplatin-induced AKI. Funding: Government Support – Non-U.S.