title: Autonomous and nonautonomous functions for Hox/Pbx in branchiomotor neuron development.
abstract: The vertebrate branchiomotor neurons are organized in a pattern that corresponds with the segments, or rhombomeres, of the developing hindbrain and have identities and behaviors associated with their position along the anterior/posterior axis. These neurons undergo characteristic migrations in the hindbrain and project from stereotyped exit points. We show that lazarus/pbx4, which encodes an essential Hox DNA-binding partner in zebrafish, is required for facial (VIIth cranial nerve) motor neuron migration and for axon pathfinding of trigeminal (Vth cranial nerve) motor axons. We show that lzr/pbx4 is required for Hox paralog group 1 and 2 function, suggesting that Pbx interacts with these proteins. Consistent with this, lzr/pbx4 interacts genetically with hoxb1a to control facial motor neuron migration. Using genetic mosaic analysis, we show that lzr/pbx4 and hoxb1a are primarily required cell-autonomously within the facial motor neurons; however, analysis of a subtle non-cell-autonomous effect indicates that facial motor neuron migration is promoted by interactions amongst the migrating neurons. At the same time, lzr/pbx4 is required non-cell-autonomously to control the pathfinding of trigeminal motor axons. Thus, Pbx/Hox can function both cell-autonomously and non-cell-autonomously to direct different aspects of hindbrain motor neuron behavior.
authors.affiliation: Howard Hughes Medical Institute, Division of Basic Science, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA.
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: Cooper
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Leisenring
authors.forename: Cecilia B
authors.initials: CB
authors.lastname: Moens
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002465:Cell Movement / Q000235:genetics; D004268:DNA-Binding Proteins; D005154:Facial Nerve / Q000196:embryology; D018390:Gene Targeting; D005801:Genes, Homeobox; D016695:Glycosyltransferases / Q000235:genetics; D049452:Green Fluorescent Proteins; D018398:Homeodomain Proteins / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics; D009030:Mosaicism; D009046:Motor Neurons / Q000166:cytology*; D009434:Neural Pathways / Q000196:embryology; D012249:Rhombencephalon / Q000196:embryology; D014276:Trigeminal Nerve / Q000196:embryology; D015027:Zebrafish / Q000235:genetics* / Q000254:growth & development*; D029961:Zebrafish Proteins / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C101121:HOXB1 homeodomain protein; D018398:Homeodomain Proteins; D008164:Luminescent Proteins; C486619:Pbx4 protein, zebrafish; D029961:Zebrafish Proteins; C489831:hoxa2b protein, zebrafish; D049452:Green Fluorescent Proteins; D016695:Glycosyltransferases; C086735:heptosyltransferase