Abstract 15949: Post-transcriptional Regulation of Cardiac Pathological Remodeling-- Role of Cytosolic Rbfox1c

Abstract

Post-transcriptional regulation plays a key role in transcriptome reprogramming during cardiac development and pathogenesis. In previous study, we have identified that loss of RBFox1 is a molecular hallmark associated with cardiac pathological hypertrophy and heart failure. We further demonstrate that RBFox1 regulates cardiac gene expression and function at post-transcriptional level through targeted RNA splicing in nuclei. However, RBFox1 gene also generates a cytosolic isoform RBFox1c, suggesting that it might also regulate other aspects of post-transcriptional regulation in heart. We detected that RBFox1c mRNA constituted 40% of total RBFox1 level in normal adult heart but repressed in diseased heart. In RBFox1-cKO mice, enhanced cardiac fibrosis was associated with loss of cardiac function following MI or TAC. Restoration of RBFox1c expression (RBFox1c-TG) significantly reduced cardiac fibrosis. RNA sequencing in RBFox1c expressing cardiomyocytes showed that RBFox1c specifically suppressed the expression of pro-inflammatory genes. The pro-inflammatory genes were induced in the RBFox1 deficient hearts but suppressed upon cardiomyocyte specific RBFox1c expression. In vitro, RBFox1c expression in NRVM suppressed PE induced proinflammatory genes and significantly blocked the effects of the conditioned media on fibroblast proliferation. De novo motif discovery identified a significant enrichment of the conserved RBFox1 binding motif in the 3’UTRs of the RBFox1c dependent genes. RNA-CLIP analysis further demonstrated a direct binding of RBFox1c to the pro-inflammatory gene 3’UTR. We characterized the interactome of RBFox1c and found RBFox1c specifically interacted with a component of the RNA non-sense mediated decay machinery-Upf1. RBFox1c interaction with Upf1 in cardiomyocytes was diminished upon hypertrophic stress. By inactivation of Upf1 via siRNA, we demonstrated that RBFox1c mediated repression of proinflammatory genes was Upf1 dependent. Finally, by temporally induced expression of RBFox1c in post-TAC heart, we provided proof-of-concept evidence that targeted expression of RBFox1c was sufficient to ameliorate pathological remodeling and progression of heart failure as a potential gene-based therapy.