Knockdown of SCN5A alters metabolic-associated genes and aggravates hypertrophy in the cardiomyoblast.

SCN5A mutations have been reported to cause various cardiomyopathies in humans. Most of the SCN5A mutations causes loss of function and thereby, alters the overall cellular function. Therefore, to understand the loss of SCN5A function in cardiomyocytes, we have knocked down the SCN5A gene (SCN5A-KD) in H9c2 cells and explored the cell phenotype and molecular behaviors in the presence and absence of isoproterenol (ISO), an adrenergic receptor agonist that induces cardiac hypertrophy. Expression of several genes related to hypertrophy, inflammation, fibrosis, and energy metabolism pathways were evaluated. It was found that the mRNA expression of hypertrophy-related gene, brain (B-type) natriuretic peptide (BNP) was significantly increased in SCN5A-KD cells as compared to 'control' H9c2 cells. There was a further increase in the mRNA expressions of BNP and βMHC in SCN5A-KD cells after ISO treatment compared to their respective controls. Pro-inflammatory cytokine, tumor necrosis factor-alpha expression was significantly increased in 'SCN5A-KD' H9c2 cells. Further, metabolism-related genes like glucose transporter type 4, cluster of differentiation 36, peroxisome proliferator-activated receptor alpha, and peroxisome proliferator-activated receptor-gamma were significantly elevated in the SCN5A-KD cells as compared to the control cells. Upregulation of these metabolic genes is associated with increased ATP production. The study revealed that SCN5A knock-down causes alteration of gene expression related to cardiac hypertrophy, inflammation, and energy metabolism pathways, which may promote cardiac remodelling and cardiomyopathy.