title: The evolution of basal progenitors in the developing non-mammalian brain.
abstract: The amplification of distinct neural stem/progenitor cell subtypes during embryogenesis is essential for the intricate brain structures present in various vertebrate species. For example, in both mammals and birds, proliferative neuronal progenitors transiently appear on the basal side of the ventricular zone of the telencephalon (basal progenitors), where they contribute to the enlargement of the neocortex and its homologous structures. In placental mammals, this proliferative cell population can be subdivided into several groups that include Tbr2(+) intermediate progenitors and basal radial glial cells (bRGs). Here, we report that basal progenitors in the developing avian pallium show unique morphological and molecular characteristics that resemble the characteristics of bRGs, a progenitor population that is abundant in gyrencephalic mammalian neocortex. Manipulation of LGN (Leu-Gly-Asn repeat-enriched protein) and Cdk4/cyclin D1, both essential regulators of neural progenitor dynamics, revealed that basal progenitors and Tbr2(+) cells are distinct cell lineages in the developing avian telencephalon. Furthermore, we identified a small population of subapical mitotic cells in the developing brains of a wide variety of amniotes and amphibians. Our results suggest that unique progenitor subtypes are amplified in mammalian and avian lineages by modifying common mechanisms of neural stem/progenitor regulation during amniote brain evolution.
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyo-ku, Kyoto 606-0823, Japan Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan tadnom@koto.kpu-m.ac.jp.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Neural Network Project, Department of Neural Development and Regeneration, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ohtaka-Maruyama
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyo-ku, Kyoto 606-0823, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yamashita
authors.affiliation: Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Wakamatsu
authors.affiliation: Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: DFG-Centre for Regenerative Therapies Dresden, Faculty of Medicine, TUD, Fetscherstrasse 105, 01307 Dresden, Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Calegari
authors.affiliation: Department of Biology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan Division of Companion Diagnostics, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo 173-8610, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyo-ku, Kyoto 606-0823, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Gotoh
authors.affiliation: Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyo-ku, Kyoto 606-0823, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ono
mesh_terms: D000558:Ambystoma mexicanum; D000818:Animals; D001479:Basal Ganglia / Q000166:cytology* / Q000196:embryology*; D019070:Cell Lineage / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D002642:Chick Embryo; D019938:Cyclin D1 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D048309:Monodelphis / Q000196:embryology; D019579:Neocortex / Q000166:cytology / Q000196:embryology*; D058953:Neural Stem Cells / Q000166:cytology*; D009474:Neurons / Q000166:cytology*; D014426:Turtles / Q000196:embryology; D014982:Xenopus laevis
chemical_list: D019938:Cyclin D1; D051358:Cyclin-Dependent Kinase 4
keywords: Amniote; Axolotl; Basal progenitor; Chicken; Eomes; Evolution; Gpsm2; Mouse; Opossum; Pallium; Tbr2; Turtle; Xenopus