title: Ol-insm1b, a SNAG family transcription factor involved in cell cycle arrest during medaka development.
abstract: Through whole-mount in situ hybridisation screen on medaka (Oryzias latipes) brain, Ol-insm1b, a member of the Insm1/Mlt1 subfamily of SNAG-domain containing genes, has been isolated. It is strongly expressed during neurogenesis and pancreas organogenesis, with a pattern that suggests a role in cell cycle exit. Here, we describe Ol-insm1b expression pattern throughout development and in adult brain, and we report on its functional characterisation. Our data point to a previously unravelled role for Ol-insm1b as a down-regulator of cell proliferation during development, as it slows down the cycle without triggering apoptosis. Clonal analysis demonstrates that this effect is cell-autonomous, and, through molecular dissection studies, we demonstrate that it is likely to be non-transcriptional, albeit mediated by zinc-finger domains. Additionally, we report that Ol-insm1b mRNA, when injected in one cell of two-cell stage embryos, exhibits a surprising behaviour: it does not spread uniformly amongst daughter cells but remains cytoplasmically localised in the progeny of the injected blastomere. Our experiments suggest that Insm1 is a negative regulator of cell proliferation, possibly through mechanisms that do not involve modulation of transcription.
authors.affiliation: INRA MSNC Group, DEPSN, Institut Fessard, CNRS, 1 Avenue de la Terrasse, 91198 GIF-SUR-YVETTE, France. ecandal@usc.es
authors.forename: Eva
authors.initials: E
authors.lastname: Candal
authors.forename: Alessandro
authors.initials: A
authors.lastname: Alunni
authors.forename: Violette
authors.initials: V
authors.lastname: Thermes
authors.forename: Françoise
authors.initials: F
authors.lastname: Jamen
authors.forename: Jean-Stéphane
authors.initials: JS
authors.lastname: Joly
authors.forename: Franck
authors.initials: F
authors.lastname: Bourrat
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D029941:Fish Proteins / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009990:Oryzias / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D010802:Phylogeny; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D014157:Transcription Factors