LncRNA FTX promotes myocardial fibrosis by sponging miR-335-3p to regulate TFEC/ILK signaling

Myocardial fibrosis is a pivotal contributor to heart failure progression. This study aimed to investigate the molecular mechanisms underlying the role of transcription factor EC (TFEC) in myocardial fibrosis. Myocardial fibrosis was induced in mice via isoproterenol (ISO) administration, and human cardiac fibroblasts (CFs) were stimulated with TGF-β1. Gene overexpression or knockdown was achieved through transfection. Gene and protein expression levels were quantified using quantitative real-time PCR (qRT-PCR) and Western blotting. Fibrotic changes, including collagen deposition and the expression of fibrotic markers, were assessed via Sirius red staining and immunohistochemistry. Subcellular localization of long noncoding RNA 5′ to Xist (LncRNA FTX) was confirmed using subcellular fractionation, qRT-PCR, and fluorescence in situ hybridization (FISH). Dual-luciferase reporter assays, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP) were performed to validate gene interactions. TFEC and integrin-linked kinase (ILK) were upregulated in TGF-β1-stimulated CFs. TFEC silencing reduced extracellular matrix (ECM) deposition and attenuated myocardial fibrosis in vitro and in vivo. TFEC transcriptionally activated ILK by directly binding to its promoter. Furthermore, TFEC was identified as a direct target of miR-335-3p, whose downregulation in myocardial fibrosis led to diminished repression of TFEC. LncRNA FTX was upregulated in myocardial fibrosis and functioned as a competing endogenous RNA (ceRNA) by sponging miR-335-3p to modulate TFEC expression. The LncRNA FTX/miR-335-3p/TFEC/ILK axis represents a critical regulatory pathway in myocardial fibrosis progression.