title: Runx3-regulated expression of two Ntrk3 transcript variants in dorsal root ganglion neurons.
abstract: Somatosensation is divided into proprioception and cutaneous sensation. Dorsal root ganglion (DRG) neurons project their fibers toward peripheral targets including muscles and skin, and centrally to the spinal cord. Proprioceptive DRG neurons transmit information from muscle spindles and Golgi tendon organs to the spinal cord. We previously showed that Runt-related transcription factor 3 (Runx3) is expressed in these neurons and their projections to the ventral spinal cord and muscle spindles are lost in Runx3-deficient (Runx3(-/-) ) mouse embryos. Although Runx3 is likely to contribute to the fate decision and projection of proprioceptive DRG neurons, the precise roles for Runx3 in these phenomena are unknown. To identify genes regulated by Runx3 in embryonic DRGs, we performed microarray analyses using cDNAs isolated from wild-type and Runx3(-/-) DRGs of embryonic day (E) 12.5 and selected two transcript variants of the tyrosine kinase receptor C (TrkC) gene. These variants, Ntrk3 variant 1 (Ntrk3-v1) and variant 2 (Ntrk3-v2), encode full-length and truncated receptors of neurotrophin-3, respectively. Using double in situ hybridization, we found that most of Ntrk3-v1 mRNA expression in E14.5 DRGs depended on Runx3 but that more than half of Ntrk3-v2 mRNA one were expressed in a Runx3-independent manner. Furthermore, our data revealed that the rate of Ntrk3-v1 and Ntrk3-v2 colocalization in DRGs changed from E14.5 to E18.5. Together, our data suggest that Runx3 may play a crucial role in the development of DRGs by regulating the expression of Ntrk3 variants and that DRG neurons expressing Ntrk3-v1 but not Ntrk3-v2 may differentiate into proprioceptive ones.
authors.affiliation: Department of Neurobiology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.|Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Ogihara
authors.affiliation: Department of Neurobiology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.|Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ozaki
authors.affiliation: Division of Anatomical Science, Department of Functional Morphology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yoshikawa
authors.affiliation: Department of Neurobiology, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.|Doctoral Program in Kansei, Behavioral and Brain Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiga
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D050677:Core Binding Factor Alpha 3 Subunit / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000378:metabolism; D020812:Receptor, trkC / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D050677:Core Binding Factor Alpha 3 Subunit; D020033:Protein Isoforms; C493730:Runx3 protein, mouse; D020812:Receptor, trkC
keywords: dorsal root ganglion; neural network; neurotrophic factor; transcription factor