A positive feedback regulation of Heme oxygenase 1 by CELF1 in cardiac myoblast cells

As an RNA binding protein, CUG-BP Elav-like family (CELF) has been shown to be critical for heart biological functions. However, no reports have revealed the function of CELF1 in hypertrophic cardiomyopathy (HCM). Hinted by RNA immunoprecipitation-sequencing (RIP-seq) data, the influence of the CELF protein on heme oxygenase-1 (HO-1) expression was tested by modulating CELF1 levels. Cardiac hypertrophy is related to oxidative stress-induced damage. Hence, the cardiovascular system may be protected against further injury by upregulating the expression of antioxidant enzymes, such as HO-1. During the past two decades, research has demonstrated the central role of HO-1 in the protection against diseases. Thus, understanding the molecular mechanisms underlying the modulation of HO-1 expression is profoundly important for developing new strategies to prevent cardiac hypertrophy. To elucidate the molecular mechanisms underlying HO-1 regulation by the CELF protein, we performed RNA immunoprecipitation (RIP), biotin pull-down analysis, luciferase reporter and mRNA stability assays. We found that the expression of HO-1 was downregulated by CELF1 through the conserved GU-rich elements (GREs) in HO-1 3'UTR transcripts. Correspondingly, CELF1 expression was regulated by controlling the release of carbon monoxide (CO) in H9C2 cells. The CELF1-HO-1-CO regulation axis constituted a novel positive feedback circuit. In addition, we detected the potential involvement of CELF1 and HO-1 in samples from HCM patients. We found that CELF1 and CELF2, but not HO-1, were highly expressed in HCM heart samples. Thus, a manipulation targeting CELF1 could be developed as a potential therapeutic option for cardiac hypertrophy.