RBM4 participates in cell differentiation by regulating tissue-specific alternative pre-mRNA splicing. RBM4 also has been implicated in neurogenesis in the mouse embryonic brain. Using mouse embryonal carcinoma P19 cells as a neural differentiation model, we observed a temporal correlation between RBM4 expression and a change in splicing isoforms of Numb, a cell-fate determination gene. Knockdown of RBM4 affected the inclusion/exclusion of exons 3 and 9 ofNumbin P19 cells. RBM4-deficient embryonic mouse brain also exhibited aberrant splicing ofNumbpre-mRNA. Using a splicing reporter minigene assay, we demonstrated that RBM4 promoted exon 3 inclusion and exon 9 exclusion. Moreover, we found that RBM4 depletion reduced the expression of the proneural geneMash1, and such reduction was reversed by an RBM4-induced Numb isoform containing exon 3 but lacking exon 9. Accordingly, induction of ectopic RBM4 expression in neuronal progenitor cells increasedMash1expression and promoted cell differentiation. Finally, we found that RBM4 was also essential for neurite outgrowth from cortical neuronsin vitro Neurite outgrowth defects of RBM4-depleted neurons were rescued by RBM4-induced exon 9-lacking Numb isoforms. Therefore, our findings indicate that RBM4 modulates exon selection ofNumbto generate isoforms that promote neuronal cell differentiation and neurite outgrowth.
Date:
2016-05
Relation:
Molecular Biology of the Cell. 2016 May ;27(10):1676-1683.
