title: Two critical periods of Sonic Hedgehog signaling required for the specification of motor neuron identity.
abstract: Antibodies that block Sonic Hedgehog (SHH) signaling have been used to show that SHH activity is required for the induction of floor plate differentiation by the notochord and independently for the induction of motor neurons by both the notochord and midline neural cells. Motor neuron generation depends on two critical periods of SHH signaling: an early period during which naive neural plate cells are converted into ventralized progenitors and a late period that extends well into S phase of the final progenitor cell division, during which SHH drives the differentiation of ventralized progenitors into motor neurons. The ambient SHH concentration during the late period determines whether ventralized progenitors differentiate into motor neurons or interneurons, thus defining the pattern of neuronal cell types generated in the neural tube.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA.
authors.forename: J
authors.initials: J
authors.lastname: Ericson
authors.forename: S
authors.initials: S
authors.lastname: Morton
authors.forename: A
authors.initials: A
authors.lastname: Kawakami
authors.forename: H
authors.initials: H
authors.lastname: Roelink
authors.forename: T M
authors.initials: TM
authors.lastname: Jessell
mesh_terms: D000818:Animals; D019521:Body Patterning; D002454:Cell Differentiation; D002455:Cell Division; D002490:Central Nervous System / Q000166:cytology / Q000196:embryology*; D002642:Chick Embryo; D004627:Embryonic Induction; D053823:Hedgehog Proteins; D007395:Interneurons; D008954:Models, Biological; D009046:Motor Neurons; D009672:Notochord / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D013234:Stem Cells; D013997:Time Factors; D015534:Trans-Activators
chemical_list: D053823:Hedgehog Proteins; D011506:Proteins; D015534:Trans-Activators