Specification of motor neuron identity by the MNR2 homeodomain protein.
Sonic hedgehog signaling controls the differentiation of motor neurons in the ventral neural tube, but the intervening steps are poorly understood. A differential screen of a cDNA library derived from a single Shh-induced motor neuron has identified a novel homeobox gene, MNR2, expressed by motor neuron progenitors and transiently by postmitotic motor neurons. The ectopic expression of MNR2 in neural cells initiates a program of somatic motor neuron differentiation characterized by the expression of homeodomain proteins, by neurotransmitter phenotype, and by axonal trajectory. Our results suggest that the Shh-mediated induction of a single transcription factor, MNR2, is sufficient to direct somatic motor neuron differentiation.
Tanabe
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Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA.
William
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Jessell
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TM
D000818:Animals; D002454:Cell Differentiation; D002642:Chick Embryo; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis; D009046:Motor Neurons / Q000166:cytology* / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D051763:PAX7 Transcription Factor; D013234:Stem Cells; D014157:Transcription Factors / Q000235:genetics
D018398:Homeodomain Proteins; C115037:MNR2 protein, vertebrate; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D051763:PAX7 Transcription Factor; D014157:Transcription Factors