RBM45 is an m6A-binding protein that affects neuronal differentiation and the splicing of a subset of pre-mRNAs II

Here, we identify RNA-binding motif containing protein 45 (RBM45) as a novel m⁶A reader, enriched in the brain, and highly expressed during embryonic neurodevelopment. We demonstrate that RBM45 recognizes intronic m⁶A and that its primary role is as a direct regulator of pre-mRNA splicing for its target genes, many of which are associated with neurodevelopment. Furthermore, we show that RBM45 is absolutely required for proper differentiation in cultured SH-SY5Y neuroblastoma cells, and that RBM45 regulates splicing of neurodevelopmental target genes central to the activation of gene expression programs that regulate differentiation in vitro. Transcriptomic profiling of RBM45 binding sites and target genes (CLIP-seq) in wild-type (WT) and m6A-depleted (Mettl3 KO) mHippoE2 cells expressing FLAG-HA-Rbm45