Abstract 16593: The DEAD-Box RNA Helicase Ddx41 Contributes to Adverse Cardiac Remodeling During Pressure Overload Through Modulation of RNA Metabolism

Introduction: RNA metabolism represents an essential biochemical process that governs protein biosynthesis, an operation that is modulated by RNA-binding proteins. Although shifts in RNA metabolism have been implicated in the pathogenesis of heart failure, the role of RNA-binding proteins in the heart remains largely unknown. Methods: Whole-genome CRISPRi screening was performed in HL-1 cardiomyocyte cell line transduced with dCAS9-KRAB. Phenylephrine, cobalt chloride and hydrogen peroxide were used as pathological stressors. Neonatal rat ventricular myocytes (NRVMs) were used for further in vitro experiments. DNA damage and mitochondrial function were assessed by phospho-H2AX detection and mitochondrial membrane potential assay, respectively. Transcriptome was assessed in NRVMs treated with Ddx41 or control siRNA. RNA Immunoprecipitation sequencing (RIP-seq) was performed by using NRVMs overexpressing FLAG-tag-labelled Ddx41. 8- to 12-week old wild-type and transgenic mice with cardiomyocyte-specific overexpression of Ddx41 were used for animal experiments. Pressure overload was induced by transverse aortic constriction (TAC). Cardiac phenotype was assessed by echocardiographic and histological analyses. Results: CRISPRi screening and validation experiment identified Ddx41, a DEAD-box RNA helicase, as one of molecules whose inhibition protects HL-1 cardiomyocytes against various pathological stressors. Knockdown of Ddx41 showed protective effect in NRVMs against doxorubicin stress with improvement of DNA damage, whereas overexpression of Ddx41 induced mitochondrial dysfunction. Transcriptome analysis using NRVMs demonstrated that Ddx41 knockdown alters expression levels of genes related to cardiac hypertrophy, energy metabolism, extracellular matrix formation and wound healing. RIP-seq analysis revealed that Ddx41 binds to mRNAs of genes related to inflammatory responses. Ddx41-Tg mice showed higher mortality and exacerbated adverse cardiac remodeling after TAC, compared with wild-type mice. Conclusions: Our results suggest that Ddx41 contributes to adverse cardiac remodeling during pressure overload through modulation of RNA metabolism. Ddx41 might be a novel therapeutic target for heart failure.