FTO-Mediated m6A Modification of EGR1 mRNA Promotes Podocyte Injury and Inflammation via STING1 in Diabetic Kidney Disease

Background: Diabetic kidney disease (DKD), a common microvascular complication of diabetes, is the leading cause of end-stage kidney disease and podocytes injury is the main determinant of DKD. Fat-mass and obesity- associated protein (FTO), the first RNA demethylase, has been reported to be associated with podocyte injury. In our previous studies, we conducted MeRIP-seq and RNA-seq in podocytes by regulating FTO and identified early growth response 1 (EGR1). However, its role in DKD has not been fully clarified. Methods: real-time PCR and Western blot were performed to detect the expression of FTO, and EGR1 in podocyte, while immunostaining were performed to detect the expression and localization of EGR1 in DKD patients. Spearman analysis were used to evaluate the correlation between EGR1 and kidney function. Dual-luciferase reporter gene assay, actinomycin D assay, and RIP analysis were performed to clarify the mechanism by which FTO regulates EGR1 expression. real-time PCR, Western blot, and ELISA were used to assess podocyte injury. Transcriptome sequencing were used to screen STING1, the downstream gene of EGR1. Podocyte-specific EGR1 knockout mice, and podocyte-specific AAV9 harboring Egr1 mice were established to observe kidney injury in vivo. Results: FTO enhanced EGR1 mRNA stability in an m6A-YTHDF2 dependent manner. EGR1 expression was up-regulated in podocytes of DKD patients, and correlated with the severity of DKD. Silence of EGR1 significantly alleviated HG-induced podocytes injury and inflammation, while its overexpression aggravated these responses. Mechanistically, EGR1 promotes podocyte injury and inflammation by upregulating STING1. In vivo, podocyte-specific deletion of EGR1 alleviated podocyte injury in high fat diet and streptozotocin-induced diabetic mice, while podocyte-specific overexpression of EGR1 exacerbated podocyte injury. Conclusion: This study suggested that FTO-mediated m6A modification of EGR1 is an important mechanism of podocyte injury in DKD, which will be a potential approach for the treatment of DKD. Funding: Government Support – Non-U.S.