title: Origin of climbing fiber neurons and their developmental dependence on Ptf1a.
abstract: Climbing fiber (CF) neurons in the inferior olivary nucleus (ION) extend their axons to Purkinje cells, playing a crucial role in regulating cerebellar function. However, little is known about their precise place of birth and developmental molecular machinery. Here, we describe the origin of the CF neuron lineage and the involvement of Ptf1a (pancreatic transcription factor 1a) in CF neuron development. Ptf1a protein was found to be expressed in a discrete dorsolateral region of the embryonic caudal hindbrain neuroepithelium. Because expression of Ptf1a is not overlapping other transcription factors such as Math1 (mouse atonal homolog 1) and Neurogenin1, which are suggested to define domains within caudal hindbrain neuroepithelium (Landsberg et al., 2005), we named the neuroepithelial region the Ptf1a domain. Analysis of mice that express beta-galactosidase from the Ptf1a locus revealed that CF neurons are derived from the Ptf1a domain. In contrast, retrograde labeling of precerebellar neurons indicated that mossy fiber neurons are not derived from Ptf1a-expressing progenitors. We could observe a detailed migratory path of CF neurons from the Ptf1a domain to the ION during embryogenesis. In Ptf1a null mutants, putative immature CF neurons produced from this domain were unable to migrate or differentiate appropriately, resulting in a failure of ION formation. Apoptotic cells were observed in the mutant hindbrain. Furthermore, the fate of some cells in the Ptf1a lineage were changed to mossy fiber neurons in Ptf1a null mutants. These findings clarify the precise origin of CF neurons and suggest that Ptf1a controls their fate, survival, differentiation, and migration during development.
authors.affiliation: Department of Pathology and Tumor Biology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Yamada
authors.forename: Mami
authors.initials: M
authors.lastname: Terao
authors.forename: Toshio
authors.initials: T
authors.lastname: Terashima
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Fujiyama
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Yo-ichi
authors.initials: Y
authors.lastname: Nabeshima
authors.forename: Mikio
authors.initials: M
authors.lastname: Hoshino
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D002531:Cerebellum / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D009415:Nerve Net / Q000196:embryology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009847:Olivary Nucleus / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D011247:Pregnancy; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D014157:Transcription Factors; C062602:transcription factor PTF1