Silencing the fibronectin gene (FN1) improves NaCl‐induced cardiac fibrosis via ferritinophagy‐mediated ferroptosis in a nuclear receptor coactivator 4 (NCOA4)‐dependent manner

Background and Purpose High‐salt diet (HSD) induces heart damage, including cardiac fibrosis, independent of blood pressure. Exploring the underlying molecular mechanisms is of significant clinical value. Experimental Approach Male rats or neonatal rat cardiac fibroblasts (NRCFs) were treated with HSD or sodium chloride (NaCl) to induce cardiac fibrosis in vivo and in vitro , respectively. Exosome high‐throughput sequencing was performed from exosomes isolated from culture supernatants of NRCFs treated with/without NaCl. Key Results First, HSD and NaCl induced myocardial fibrosis and ferroptosis in vivo and in vitro , respectively. The results of exosome high‐throughput sequencing, along with validation experiments, showed that NaCl increased fibronectin gene ( Fn1 ) expression via post‐transcriptional regulation in NRCFs. Cardiac‐specific silencing of Fn1 attenuated HSD‐induced cardiac fibrosis and ferroptosis, while Fn1 overexpression counteracted these effects. Also, GW4869‐mediated exosome depletion reduced extracellular FN‐1 but did not rescue NaCl‐induced cardiac fibrosis. Moreover, silencing Fn1 inhibited NaCl‐induced increase of nuclear receptor coactivator 4 (NCOA4). Fn1 loss exacerbated NCOA4 degradation. Next, inhibition of NOCA4‐mediated ferritinophagy improved HSD‐induced cardiac fibrosis, whereas NCOA4 overexpression hampered the antifibrotic effects of silencing Fn1 in NaCl‐induced NRCFs. Besides, autophagy inhibitor 3‐MA ameliorated NaCl‐induced cardiac fibrosis and ferroptosis, indicating that autophagy was essential for NCOA4‐mediated ferroptosis. Conclusion and Implications Overall, our finding identified that silencing Fn1 possessed beneficial effects against NaCl‐induced cardiac fibrosis through downregulating the ferroptosis of NRCFs, which was attributed to the inhibition of NOCA4‐mediated ferritinophagy.