title: Sustained Hox5 gene activity is required for respiratory motor neuron development.
abstract: Respiration in mammals relies on the rhythmic firing of neurons in the phrenic motor column (PMC), a motor neuron group that provides the sole source of diaphragm innervation. Despite their essential role in breathing, the specific determinants of PMC identity and patterns of connectivity are largely unknown. We show that two Hox genes, Hoxa5 and Hoxc5, control diverse aspects of PMC development including their clustering, intramuscular branching, and survival. In mice lacking Hox5 genes in motor neurons, axons extend to the diaphragm, but fail to arborize, leading to respiratory failure. Genetic rescue of cell death fails to restore columnar organization and branching patterns, indicating these defects are independent of neuronal loss. Unexpectedly, late Hox5 removal preserves columnar organization but depletes PMC number and branches, demonstrating a continuous requirement for Hox function in motor neurons. These findings indicate that Hox5 genes orchestrate PMC development through deployment of temporally distinct wiring programs.
authors.affiliation: Howard Hughes Medical Institute, New York University School of Medicine, Smilow Neuroscience Program, Department of Physiology and Neuroscience, New York, New York, USA.
authors.forename: Polyxeni
authors.initials: P
authors.lastname: Philippidou
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Walsh
authors.forename: Josée
authors.initials: J
authors.lastname: Aubin
authors.forename: Lucie
authors.initials: L
authors.lastname: Jeannotte
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Dasen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003964:Diaphragm / Q000196:embryology* / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009046:Motor Neurons / Q000166:cytology / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology; D009924:Organ Culture Techniques; D010750:Phosphoproteins / Q000235:genetics* / Q000502:physiology; D010791:Phrenic Nerve / Q000196:embryology / Q000502:physiology; D014157:Transcription Factors
chemical_list: C118987:HOXC5 protein, human; D018398:Homeodomain Proteins; C059637:Hoxa5 protein, mouse; D010750:Phosphoproteins; D014157:Transcription Factors