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SPARC Drives Tubulointerstitial Fibrosis through Regulating the CBP-DOT1L Pathway
Huimin Jiang1, Qing Yang1, Kuo Wang1
1Department of Nephrology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Children and Adolescents' Health and Diseases, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatric Metabolism and Inflammatory Diseases, Chongqing, P.R. China.
None:
Renal tubulointerstitial fibrosis (TIF) is a central pathological feature driving the progression of chronic kidney disease (CKD) toward end-stage renal failure. Despite advances in understanding fibrotic mechanisms, effective anti-fibrotic therapies remain limited. Here, we identify SPARC, a matricellular protein expressed in proximal tubular epithelial cells (PTECs), as a key mediator of TIF. SPARC expression strongly correlates with fibrosis severity in both human CKD biopsies and murine models of unilateral ureteral obstruction (UUO) and ischemia-reperfusion injury (IRI). Genetic ablation of Sparc markedly attenuates renal fibrosis in these models. Mechanistically, SPARC stabilizes DOT1L protein, enhancing H3K79 di-methylation (H3K79me2) and promoting fibrotic changes in PTECs. This process is orchestrated by the acetyltransferase CBP, whose regulation of DOT1L stability depends on MEK-ERK signaling. The SPARC-CBP-DOT1L axis thus defines a previously unrecognized epigenetic pathway driving renal fibrosis. Our findings establish SPARC as a critical driver of TIF and highlight the SPARC-CBP-DOT1L signaling cascade as a promising therapeutic target for halting fibrotic progression in CKD.
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