Peroxisome Proliferator-Activated Receptor Family of Lipid-Activated Nuclear Receptors Alpha Silencing Promotes Oxidative Stress and Hypertrophic Phenotype in Rat Cardiac Cells.

Abstract

The peroxisome proliferator-activated receptor family of lipid-activated nuclear receptors (PPARs) plays a critical role in the regulation of cellular lipid metabolism. In cardiac muscle, PPARα is highly expressed and regulates genes involved in fatty acid oxidation, but its activity is downregulated in hypertrophic hearts; however, the consequences of chronic PPARα deficiency on the cardiac contractile apparatus remain unclear. This study aimed to investigate the PPARα role in hypertrophic phenotype and to evaluate the potential effects of the antioxidant Ebselen (Ebs) treatment on changes associated with PPARα depletion. We thus generated an in vitro model of cardiac hypertrophy by stable silencing of the PPARA gene in H9c2 rat cardiomyoblasts. We observed that PPARα silencing induces a hypertrophic phenotype, characterized by increased NPPB and decreased FBXO32 expression, mitochondrial dysregulation, impaired lipid metabolism, oxidative stress, and ferroptosis-related alterations. Epigenetically, H3K27ac levels increased while H3K27me3 decreased. Moreover, miR-34a, miR-132, and miR-331 were downregulated, implicating a miRNA-mediated mechanism in PPARα-linked cardiac hypertrophy. Treatment with Ebs, a redox-active compound with inhibitory effects on ferroptosis and epigenetics, reversed hypertrophic phenotype and restored miRNA levels. In conclusion, we found that PPARα depletion promotes oxidative stress and hypertrophic phenotype and that Ebs may act as a potential therapeutic agent.