Contribution of hypoxia-inducible 1alpha to pathogenesis of sarcomeric hypertrophic cardiomyopathy

Aims: Hypertrophic cardiomyopathy (HCM) caused by autosomal-dominant mutations in genes coding for structural sarcomeric proteins, is the most common inherited heart disease. HCM is associated with progressive myocardial hypertrophy, fibrosis, ventricular dysfunction, and arrhythmias. Hypoxia together with hypoxia-inducible transcription factor-1a (HIF1A) is the central master regulators of cellular hypoxia response and associated with HCM. Yet their exact role remains to be elucidated. Therefore, the effect of a cardiomyocyte-specific Hif-1a knockout (cHif1aKO) was studied in an established α-MHC719/+ HCM mouse model that exhibits the classical features of human HCM. Results: HIF-1α protein and HIF downstream targets were upregulated in left ventricular tissue of α-MHC719/+ mice. Cardiomyocyte-specific abolishment of Hif-1a did not cause cardiac abnormalities in wild type (WT) mice and resulted in amelioration of disease phenotype in α-MHC719/+ mice, as evidenced by decreased left ventricular wall thickness, reduced myocardial fibrosis, reduced disordered SRX/DRX state and diminished ROS production. In addition, cHif1aKO induced normalization of pro-hypertrophic and pro-fibrotic left ventricular remodeling signaling evidenced on whole transcriptome and proteomics analysis in α-MHC719/+ mice. Proteomics of serum samples from patients with early onset HCM compared to age-and gender-matched healthy controls revealed significant upregulation of HIF targets IGF2, LTBP1, RECK and downregulation of WDR1. Innovation and Conclusion: Overall, these results demonstrate for the first time that HIF signaling is involved in mouse and human HCM pathogenesis. Cardiomyocyte-specific knockout of Hif-1a attenuates disease phenotype in the HCM α-MHC719/+ mouse model. Targeting HIF-1α might serve as a therapeutic option to mitigate HCM disease progression.