Abstract: TH-PO1088
CAPG as a Novel Therapeutic Target in Kidney Fibrosis via Transforming Growth Factor (TGF)-β Signaling by Mediating Smad4 and CBP Interaction in Fibroblasts
Session Information
- CKD: Mechanisms - 1
October 24, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2303 CKD (Non-Dialysis): Mechanisms
Authors
- Chen, Sixiu, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Zhang, Meng, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Zhang, Tao, Sun Yat-sen University Zhongshan School of Medicine, Guangzhou, Guangdong, China
- Bonventre, Joseph V., Brigham and Women's Hospital, Boston, Massachusetts, United States
- Chen, Wei, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
Background
Fibroblast-to-myofibroblast transition is a key event in renal fibrosis (RF). However, the mechanisms remain unclear. Using single-cell RNA sequencing (scRNA-seq) from a public dataset (GSE180420), we identified that elevated expression of CAPG, a member of the gelsolin family, is associated with fibroblast activation. This study aims to investigate the role and mechanism of CAPG in RF.
Methods
We generated Capg knockout (Capg-/-) and heterozygous (Capg+/-) mice and utilized folic acid (FA) and unilateral ischemia-reperfusion injury with contralateral nephrectomy (uIRIx) models. scRNA-seq was performed on the FA model. Renal fibroblasts (NRK-49F) were transfected with CAPG-siRNA and CAPG-overexpressing (CAPG-OE) lentivirus. CUT&Tag sequencing identified CAPG-regulated pathways while immunoblotting, immunofluorescence (IF), immunoprecipitation (IP), and chromatin immunoprecipitation (ChIP) were conducted for further analysis.
Results
CAPG expression was significantly elevated in CKD patient kidney tissues compared to healthy controls and correlated with the degree of fibrosis. CAPG levels progressively increased post-FA injection. CAPG deficiency significantly reduced renal fibrosis, as evidenced by histological analysis, and reduced expression of extracellular matrix (Figure 1). scRNA-seq revealed CAPG expression predominantly in fibroblasts in fibrotic kidneys, with IF confirming nuclear localization in fibroblasts. CUT&Tag sequencing indicated CAPG-binding genes are enriched in TGF-β signaling, sharing similar binding sites with Smad proteins. IP confirmed CAPG and CBP interactions with Smad4 in NRK-49F cells. Quantitative IP demonstrated TGF-β-induced interaction between Smad4 and CBP, which was inhibited by CAPG knockdown. ChIP confirmed co-localization of CAPG and Smad4 at Col1a1 promoter region, with ChIP-qPCR showing increased CBP enrichment at Col1a1 promoter in CAPG-OE cells compared to controls.
Conclusion
CAPG is upregulated following kidney injury and promotes the interaction between Smad4 and CBP, thereby activating the TGF-β pathway. This leads to fibroblast activation and progression of RF, suggesting CAPG as a potential therapeutic target for RF.
Figure 1
Funding
- Government Support – Non-U.S.