Hippo pathway activation mediates cardiomyocyte ferroptosis to promote dilated cardiomyopathy through downregulating NFS1

Cardiomyocyte loss by regulated death modes, like apoptosis and ferroptosis, has been implicated in the development of dilated cardiomyopathy (DCM). It remains unclear whether cardiomyocyte ferroptosis occurs as a consequence of Hippo pathway activation. Using a mouse model of DCM by overexpression of Mst1 transgene (Mst1-TG) leading to Hippo pathway activation, we showed that cardiomyocyte ferroptosis was evident by transcriptomic profiles, elevated mitochondrial Fe²⁺ content, increased levels of lipid peroxidation and obvious mitochondrial damage. Transcriptome revealed significant alterations of genes participating in iron metabolism and lipid peroxidation. Treatment of Mst1-TG mice with the ferroptosis inhibitor ferrostatin-1 reduced cardiomyocyte ferroptosis and improved cardiac function. Using heart samples from human patients with DCM, we also found significant cardiomyocyte loss and lipid peroxidation. In cultured cardiomyocytes, ferroptosis was induced by treatment with erastin or YAP inhibitor verteporfin, and cell ferroptosis under these conditions was largely prevented by either iron chelation or Mst1 gene knockdown. In a strain of transgenic mice with cardiomyocyte inactivation of Mst1 (dnMst1-TG), erastin-induced ferroptosis and cardiac dysfunction, seen in control mice, were mitigated. Mechanistically, nuclear YAP and YY1 were shown to interact and bind to the Nfs1 promoter, thus mediating downregulation of Nfs1 (encoding cysteine desulfurase). Subsequent inhibition of iron-sulfur cluster (ISC) biosynthesis promoted cardiomyocyte ferroptosis and DCM phenotype. Restoration of Nfs1 expression was achieved by treatment of Mst1-TG mice with AAV9-Nfs1 virus, which alleviated ferroptosis, mitochondrial damage and DCM phenotype. In conclusion, in the DCM model with Hippo pathway activation, our findings unravel that NFS1 downregulation occurs and leads to insufficient ISC biosynthesis and cardiomyocyte ferroptosis. Our findings implicate that restoration of cardiomyocyte NFS1 level may represent a new therapeutic strategy for DCM.