Verapamil reduces collagen synthesis to alleviate ureteral scar formation by inhibiting KDM1A-mediated epigenetic silencing of SESN2

BACKGROUND: Ureteral scar formation is a fibrotic process linked with collagen synthesis. Although autophagy prevents collagen synthesis, its role in ureteral scarring remains unclear. Therefore, this study investigated the modulation of SESN2-mediated autophagy by verapamil during ureteral scar formation. METHODS: An in vitro fibrosis model was constructed using TGF-β1-stimulated primary fibroblasts. We established a rat model of ureteral stricture (US), and KN-93 was used to inhibit the phosphorylation of CaMK II. Histopathological alterations and collagen accumulation in rat ureteral tissues were examined using hematoxylin-eosin and Masson staining. The levels of Vimentin, α-SMA, and LC3 were determined using immunofluorescence. Autophagic flux was assessed using an mCherry-GFP-LC3 assay. mRNA and protein levels were assessed by RT-qPCR and Western blot, respectively. Additionally, CoIP and GST pull-down assays were used to detect the binding relationship between CaMK II and KDM1A. The interaction of H3K4me2 and KDM1A with the SESN2 promoter in fibroblasts was verified using ChIP. RESULTS: Verapamil increased autophagy in TGF-β1-stimulated fibroblasts and alleviated ureteral fibrosis in US rats by inhibiting CaMK II phosphorylation (p-CaMK II) to reduce collagen synthesis. Moreover, p-CaMK II promoted the nuclear translocation of KDM1A by phosphorylating KDM1A. Additionally, the effects of KDM1A knockdown on the autophagy and collagen synthesis in TGF-induced fibroblasts were reversed by SESN2 knockdown. Finally, KDM1A knockdown further enhanced the effect of verapamil in promoting SESN2-mediated fibroblast autophagy and suppressed collagen synthesis. CONCLUSION: Verapamil reduced collagen synthesis during ureteral scar formation by inhibiting the phosphorylation of KDM1A by p-CaMK II, thus, decreasing the demethylation of H3K4me2 on the SESN2 promoter to enhance SESN2-mediated autophagy.