Knockdown of Runx1 in cardiac fibroblasts reduced fibrosis and cytoskeletal remodeling, indicating its pivotal role in cardiac fibrosis via m6A methylation.
Does Runx1 knockdown prevent cardiac fibrosis in experimental models?
Targeting RUNX1 m6A RNA methylation mitigates cardiac fibrosis and fibroblast proliferation, offering a novel epitranscriptomic therapeutic strategy.
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Abstract Aims The RUNX family of transcription factors is critical for heart development, physiology, and cardiovascular disease. However, current models of transcription factor binding seldom incorporate RNA modifications, and the latest methods that include them remain limited. This gap impedes accurate profiling of transcription factor affinities. In particular, the role of m6A-mediated mechanisms in regulating RUNX factors during cardiac fibrosis is still poorly understood. Methods and Results RNA sequencing of human atrial fibrillation tissues identified transcription factors with enriched expression associated with cardiac gene expression. Cardiac fibroblast-specific Ythdf1 conditional knockout mice (Postn-Cre × Ythdf1flox/flox), along with Cre and wild-type controls, were subjected to ISO/TAC treatment to induce cardiac fibrosis. AAV9 vectors carrying Postn promoter-driven shRNA targeting Runx1 were administered to ISO-treated mice to evaluate its role in cardiac fibrosis. Multi-omics approaches including MeRIP-seq, single-cell RNA-seq, RNA-seq, and ChIP-seq, combined with histological and biochemical analyses, were employed to elucidate the mechanism by which YTHDF1 regulates Runx1 expression. Runx1 was reconstituted in Ythdf1-deficient cardiac fibroblasts and mouse hearts to assess its effects on fibroblast proliferation and fibrosis. Runx1 expression was elevated in human atrial fibrillation samples, experimental cardiac fibrosis models, and TGF-β1-stimulated cardiac fibroblasts. Fibroblast-specific Runx1 knockdown attenuated cytoskeletal remodeling, suppressed fibroblast proliferation, and inhibited cardiac fibrosis. Mechanistically, Runx1 upregulation was associated with increased m6A methylation on its mRNA. Site-specific m6A modification at peak₂1317 was essential for promoting YTHDF1 binding to Runx1 mRNA and enhancing its translation. This led to increased transcriptional activation of connective tissue growth factor (Ctgf), promoting cytoskeletal reorganization and collagen deposition. Importantly, epitranscriptomic inhibition of Runx1 ameliorated experimental cardiac fibrosis. Conclusions Our study reveals a novel epitranscriptomic pathway wherein YTHDF1 recognizes m6A-modified Runx1 mRNA, enhancing its translation and thereby stimulating RUNX1-mediated Ctgf transcription. This process drives cytoskeletal remodeling, cardiac fibroblast proliferation, and fibrosis in an m6A-dependent manner. These findings offer new perspectives for developing preventive strategies against cardiac fibrosis. Translational Perspectives These results indicate that YTHDF1 and transcription factor RUNX1 mRNA and protein levels were up-regulated during human AF and pathological cardiac fibrosis, demonstrate a clinically relevant role for the YTHDF1/RUNX1 axis in mitigating AF and cardiac fibrosis, and suggesting that targeting RUNX1 m6A RNA methylation may serve as a promising therapeutic strategy for treating AF and cardiac fibrosis.
Ding et al. (Thu,) reported a other. Knockdown of Runx1 in cardiac fibroblasts reduced fibrosis and cytoskeletal remodeling, indicating its pivotal role in cardiac fibrosis via m6A methylation.