title: RBM4 promotes neuronal differentiation and neurite outgrowth by modulating Numb isoform expression.
abstract: 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 of Numb in P19 cells. RBM4-deficient embryonic mouse brain also exhibited aberrant splicing of Numb pre-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 gene Mash1, 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 increased Mash1 expression and promoted cell differentiation. Finally, we found that RBM4 was also essential for neurite outgrowth from cortical neurons in 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 of Numb to generate isoforms that promote neuronal cell differentiation and neurite outgrowth.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan wtarn@ibms.sinica.edu.tw.
authors.forename: Woan-Yuh
authors.initials: WY
authors.lastname: Tarn
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Hung-Che
authors.initials: HC
authors.lastname: Kuo
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Hsin-I
authors.initials: HI
authors.lastname: Yu
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Shin-Wu
authors.initials: SW
authors.lastname: Liu
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Ching-Tzu
authors.initials: CT
authors.lastname: Tseng
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Dodda
authors.initials: D
authors.lastname: Dhananjaya
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Kuan-Yang
authors.initials: KY
authors.lastname: Hung
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Chi-Chiang
authors.initials: CC
authors.lastname: Tu
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Shuo-Hsiu
authors.initials: SH
authors.lastname: Chang
authors.affiliation: Graduate Institute of Biomedical Sciences, Chung-Gung University, Tao-Yuan City 33302, Taiwan.
authors.forename: Guo-Jen
authors.initials: GJ
authors.lastname: Huang
authors.affiliation: National Health Research Institutes, Chu-Nan 35053, Taiwan.
authors.forename: Ing-Ming
authors.initials: IM
authors.lastname: Chiu
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D005091:Exons; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism; D055495:Neurogenesis; D000071446:Neuronal Outgrowth; D009474:Neurons / Q000378:metabolism; D061251:Primary Cell Culture; D020033:Protein Isoforms / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C106293:Numb protein, mouse; D020033:Protein Isoforms; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C000620908:rbm4 protein, mouse