title: Nkx6.1 controls migration and axon pathfinding of cranial branchio-motoneurons.
abstract: As many studies have focused on the mechanisms of motoneuron specification, little is known about the factors that control the subsequent development of postmitotic motoneurons. Previously, we showed that the transcription factor Nkx6.1 is required for the early specification of somatic motoneuron progenitors in the spinal cord. Our present analysis of hindbrain motoneuron development in Nkx6.1-deficient mouse embryos reveals that the early specification of branchio-motoneurons is independent of Nkx6.1 function, but that it is required for their subsequent development. In Nkx6.1 mutant mice, we observed defects in the migration, as well as in the axon projections of branchio-motoneurons. A detailed analysis of the migratory defect in facial branchio-motoneurons reveals ectopic expression of the cell surface receptors Ret and Unc5h3 in premigratory neurons, but no changes in the rhombomeric environment. Taken together, our findings demonstrate a requirement for Nkx6.1 in the development of postmitotic motoneurons, and suggest a cell-autonomous function in the control of branchio-motoneuron migration.
authors.affiliation: Center for Molecular Neurobiology, Martinistrasse 85, 20251 Hamburg, Germany.
authors.forename: Myriam
authors.initials: M
authors.lastname: Müller
authors.forename: Normund
authors.initials: N
authors.lastname: Jabs
authors.forename: Dietrich E
authors.initials: DE
authors.lastname: Lorke
authors.forename: Bernd
authors.initials: B
authors.lastname: Fritzsch
authors.forename: Maike
authors.initials: M
authors.lastname: Sander
mesh_terms: D000818:Animals; D019521:Body Patterning; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D002465:Cell Movement / Q000502:physiology*; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D009046:Motor Neurons / Q000166:cytology / Q000502:physiology*; D036122:Receptor, EphA4 / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism
chemical_list: C101121:HOXB1 homeodomain protein; D018398:Homeodomain Proteins; C491328:Nkx6-1 protein, mouse; D011956:Receptors, Cell Surface; D036122:Receptor, EphA4