Rbfox2 is Critical for Maintaining Alternative Polyadenylation and Mitochondrial Health in Myoblasts

The RNA binding protein RBFOX2 is linked to heart and skeletal muscle diseases; yet, RBFOX2-regulated RNA networks have not been systematically identified. Although RBFOX2 has a well-known function in alternative splicing (AS), it is unclear whether RBFOX2 has other roles in RNA metabolism that affect gene expression and function. Utilizing state of the art techniques Poly(A)-ClickSeq (PAC-seq) and nanopore cDNA sequencing, we revealed a new role for RBFOX2 in fine tuning alternative polyadenylation (APA) of pre-mRNAs in myoblasts. We found that depletion of RBFOX2 altered expression of mitochondrial genes. We identified the mitochondrial gene gene that transports ATP/ADP across inner mitochondrial membrane as a target of RBFOX2. Dissecting how RBFOX2 affects APA uncovered that RBFOX2 binding motifs near the distal polyadenylation site (PAS) are critical for expression of . Consistent with changes in expression of mitochondrial genes, loss of RBFOX2 altered mitochondrial membrane potential and induced mitochondrial swelling. Our results unveiled a novel role for RBFOX2 in maintaining APA decisions and expression of mitochondrial genes in myoblasts relevant to heart diseases.