RBM4 Regulates Neuronal Differentiation of Mesenchymal Stem Cells by Modulating Alternative Splicing of Pyruvate Kinase M.
RBM4 promotes differentiation of neuronal progenitor cells and neurite outgrowth of cultured neurons via its role in splicing regulation. In this study, we further explored the role of RBM4 in neuronal differentiation. During neuronal differentiation, energy production shifts from glycolysis to oxidative phosphorylation. We found that the splice isoform change of the metabolic enzyme pyruvate kinase M (PKM) from PKM2 to PKM1 occurs during brain development and is impaired in RBM4-deficient brains. The PKM isoform change could be recapitulated in human mesenchymal stem cells (MSCs) during neuronal induction. Using a PKM minigene, we demonstrated that RBM4 plays a direct role in regulating alternative splicing of PKM. Moreover, RBM4 antagonized the function of the splicing factor PTB and induced the expression of a PTB isoform with attenuated splicing activity in MSCs. Overexpression of RBM4 or PKM1 induced the expression of neuronal genes, increased the mitochondrial respiration capacity in MSCs, and, accordingly, promoted neuronal differentiation. Finally, we demonstrated that RBM4 is induced and is involved in the PKM splicing switch and neuronal gene expression during hypoxia-induced neuronal differentiation. Hence, RBM4 plays an important role in the PKM isoform switch and the change in mitochondrial energy production during neuronal differentiation.
Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.|Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Chun-Hao
CH
Su
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Kuan-Yang
KY
Hung
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.|Department of Orthopedics, Integrative Stem Cell Center, China Medical University Hospital, Taichung, Taiwan.|Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.
Shih-Chieh
SC
Hung
Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan wtarn@ibms.sinica.edu.tw.|Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Woan-Yuh
WY
Tarn
D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000196:embryology / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D015687:Cell Hypoxia; D002460:Cell Line; D006801:Humans; D007438:Introns / Q000235:genetics; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D038941:Polypyrimidine Tract-Binding Protein / Q000378:metabolism; D011770:Pyruvate Kinase / Q000235:genetics* / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation / Q000235:genetics
D007527:Isoenzymes; C473692:RBM4 protein, human; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D038941:Polypyrimidine Tract-Binding Protein; D011770:Pyruvate Kinase
alternative splicing; hypoxia; mesenchymal stem cells; neuronal differentiation; pyruvate kinase M