title: Acquisition of glial cells missing 2 enhancers contributes to a diversity of ionocytes in zebrafish.
abstract: Glial cells missing 2 (gcm2) encoding a GCM-motif transcription factor is expressed in the parathyroid in amniotes. In contrast, gcm2 is expressed in pharyngeal pouches (a homologous site of the parathyroid), gills, and H(+)-ATPase-rich cells (HRCs), a subset of ionocytes on the skin surface of the teleost fish zebrafish. Ionocytes are specialized cells that are involved in osmotic homeostasis in aquatic vertebrates. Here, we showed that gcm2 is essential for the development of HRCs and Na(+)-Cl(-) co-transporter-rich cells (NCCCs), another subset of ionocytes in zebrafish. We also identified gcm2 enhancer regions that control gcm2 expression in ionocytes of zebrafish. Comparisons of the gcm2 locus with its neighboring regions revealed no conserved elements between zebrafish and tetrapods. Furthermore, We observed gcm2 expression patterns in embryos of the teleost fishes Medaka (Oryzias latipes) and fugu (Fugu niphobles), the extant primitive ray-finned fishes Polypterus (Polypterus senegalus) and sturgeon (a hybrid of Huso huso × Acipenser ruhenus), and the amphibian Xenopus (Xenopus laevis). Although gcm2-expressing cells were observed on the skin surface of Medaka and fugu, they were not found in Polypterus, sturgeon, or Xenopus. Our results suggest that an acquisition of enhancers for the expression of gcm2 contributes to a diversity of ionocytes in zebrafish during evolution.
authors.affiliation: Department of Anatomy, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Shono
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurokawa
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Miyake
authors.forename: Masataka
authors.initials: M
authors.lastname: Okabe
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D005880:Gills / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009990:Oryzias / Q000196:embryology / Q000235:genetics; D012867:Skin / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D023741:Takifugu / Q000196:embryology / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C501172:gcm2 protein, zebrafish; D049452:Green Fluorescent Proteins; C520788:V-ATPase subunit A, zebrafish; D025262:Vacuolar Proton-Translocating ATPases