MO427: Protein Arginine Methyltransferase 1 Increases The Expression of P63 and Promotes Renal Interstitial Fibrosis

Abstract

Abstract BACKGROUND AND AIMS Mammalian Protein Arginine Methyltransferase 1 (PRMT1) catalyzes the monomethylation and dimethylation of the Arginine residues of proteins. It has been shown that PRMT1 inhibitor attenuates renal fibrosis, however, the role of PRMT1 in renal interstitial fibrosis is not fully understood. Using kidney-specific PRMT1 knockout mice, we aimed to study the role of PRMT1 in renal fibrosis and explored its underlining mechanisms. METHOD Sham or unilateral ureteral obstruction (UUO) operation was performed in PRMT1 Ksp-cre knockout mice, which were sacrificed on day 14. The effect of PRMT 1 on renal interstitial fibrosis was further studied using PRMT1 specific inhibitor AMI-1 in WT UUO mice. RNA-seq analysis was performed to analyze differential expressed genes in WT versus PRMT 1 knockout UUO kidneys. Moreover, TGF-β stimulated HK2 renal epithelial cells were treated with various concentrations of AMI-1(2μM to 10μM). Protein samples from in vivo and in vitro experiments were collected to assess renal fibrosis. RESULTS Strong interstitial fibrosis was observed in Ksp-Cre- (WT) UUO mice as shown by Masson staining, and kidney-specific deletion of PRMT 1 gene attenuated interstitial fibrosis in mouse kidneys. The expression of collagen-I in mouse kidneys was analyzed by Western blotting. UUO operation increased the expression of collagen-I in WT mouse kidneys, which were reduced by kidney-specific deletion of PRMT 1 gene. Inhibition of AMI-1 on renal interstitial fibrosis in UUO kidneys was confirmed by Masson staining and Western blotting analysis of pro-fibrotic markers. Mechanistically, using RNA-seq analysis, we found P63 was down-regulated in PRMT 1 knockout UUO kidneys. We further confirmed the down-regulation of P63 by qPCR and Western blotting analysis in PRMT1 knockout UUO kidneys and AMI-1 treated UUO kidneys. Moreover, we showed that AMI-1 dose-dependently inhibited the expression of P63 in TGF-β stimulated HK2 renal epithelial cells, which was correlated with down-regulation of pro-fibrotic markers. CONCLUSION PRMT1 promotes renal interstitial fibrosis probably through increasing the expression of P63.