Triggering neural differentiation of ES cells by subtype switching of importin-α

Nuclear proteins are selectively imported into the nucleus by transport factors such as importin-α and importin-β. Here, we show that the expression of importin-α subtypes is strictly regulated during neural differentiation of mouse embryonic stem (ES) cells, and that the switching of importin-α subtype expression is critical for neural differentiation. Moreover, reproducing the switching of importin-α subtype expression in undifferentiated ES cells induced neural differentiation in the presence of leukaemia inhibitory factor (LIF) and serum, coordinated with the regulated expression of Oct3/4, Brn2 and SOX2, which are involved in ES–neural identity determination. These transcription factors were selectively imported into the nucleus by specific subtypes of importin-α. Thus, importin-α subtype switching has a major impact on cell differentiation through the regulated nuclear import of a specific set of transcription factors. This is the first study to propose that transport factors should be considered as major players in cell-fate determination.

[1]  H. Kondoh,et al.  Pairing SOX off: with partners in the regulation of embryonic development. , 2000, Trends in genetics : TIG.

[2]  P. Robson,et al.  Transcriptional Regulation of Nanog by OCT4 and SOX2* , 2005, Journal of Biological Chemistry.

[3]  Austin G Smith,et al.  Conversion of embryonic stem cells into neuroectodermal precursors in adherent monoculture , 2003, Nature Biotechnology.

[4]  Guangjin Pan,et al.  Identification of a Nuclear Localization Signal in OCT4 and Generation of a Dominant Negative Mutant by Its Ablation* , 2004, Journal of Biological Chemistry.

[5]  Motoki Saito,et al.  Oct-3/4 and Sox2 Regulate Oct-3/4 Gene in Embryonic Stem Cells* , 2005, Journal of Biological Chemistry.

[6]  Marc Tessier-Lavigne,et al.  Induction of midbrain dopaminergic neurons by Sonic hedgehog , 1995, Neuron.

[7]  K. Ogino,et al.  Generation of a Rat Monoclonal Antibody Specific for Importin α3/Qip1 , 2003 .

[8]  Nucleocytoplasmic Transport , 1996, Science.

[9]  S. Adam,et al.  Nuclear protein import in permeabilized mammalian cells requires soluble cytoplasmic factors , 1990, The Journal of cell biology.

[10]  H. Hamada,et al.  Interplay of SOX and POU Factors in Regulation of the Nestin Gene in Neural Primordial Cells , 2004, Molecular and Cellular Biology.

[11]  K. Ogino,et al.  Specific Monoclonal Antibody Against Nuclear Import Factor, Importin α1/Rch1 , 2004 .

[12]  Xi Chen,et al.  Reciprocal Transcriptional Regulation of Pou5f1 and Sox2 via the Oct4/Sox2 Complex in Embryonic Stem Cells , 2005, Molecular and Cellular Biology.

[13]  H. Niwa,et al.  Identification of Sox-2 regulatory region which is under the control of Oct-3/4-Sox-2 complex. , 2002, Nucleic acids research.

[14]  M. Wegner,et al.  Identification of the Nuclear Localization Signal of the POU Domain Protein Tst-1/Oct6* , 1996, The Journal of Biological Chemistry.

[15]  M. Yamaizumi,et al.  Reversible inhibition of protein import into the nucleus by wheat germ agglutinin injected into cultured cells. , 1987, Experimental cell research.

[16]  K. Mizuseki,et al.  Induction of Midbrain Dopaminergic Neurons from ES Cells by Stromal Cell–Derived Inducing Activity , 2000, Neuron.

[17]  N. Corbi,et al.  Developmental-specific activity of the FGF-4 enhancer requires the synergistic action of Sox2 and Oct-3. , 1995, Genes & development.

[18]  J. Price,et al.  Expression of the POU domain transcription factor, oct-6, is attenuated in the adult mouse telencephalon, but increased by neurotoxic damage , 2003, Experimental Neurology.

[19]  F. Bischoff,et al.  Evidence for Distinct Substrate Specificities of Importin α Family Members in Nuclear Protein Import , 1999, Molecular and Cellular Biology.

[20]  黒田 貴雄.  Octamer and Sox elements are required for transcriptional cis regulation of Nanog gene expression , 2007 .

[21]  Megan F. Cole,et al.  Core Transcriptional Regulatory Circuitry in Human Embryonic Stem Cells , 2005, Cell.

[22]  A. Clayton,et al.  A SOX9 Defect of Calmodulin-dependent Nuclear Import in Campomelic Dysplasia/Autosomal Sex Reversal* , 2003, Journal of Biological Chemistry.

[23]  Y. Yoneda,et al.  Nucleocytoplasmic protein traffic and its significance to cell function , 2000, Genes to cells : devoted to molecular & cellular mechanisms.

[24]  J. Miyazaki,et al.  Quantitative expression of Oct-3/4 defines differentiation, dedifferentiation or self-renewal of ES cells , 2000, Nature Genetics.

[25]  M. Wegner,et al.  The POU protein Oct-6 is a nucleocytoplasmic shuttling protein , 2005, Nucleic acids research.

[26]  M. Miyagi,et al.  Antibodies against 70-kD heat shock cognate protein inhibit mediated nuclear import of karyophilic proteins , 1992, The Journal of cell biology.

[27]  D. Goldfarb,et al.  Importin α: A multipurpose nuclear-transport receptor , 2004 .