title: Identification of pluripotency genes in the fish medaka.
abstract: Stem cell cultures can be derived directly from early developing embryos and indirectly from differentiated cells by forced expression of pluripotency transcription factors. Pluripotency genes are routinely used to characterize mammalian stem cell cultures at the molecular level. However, such genes have remained unknown in lower vertebrates. In this regard, the laboratory fish medaka is uniquely suited because it has embryonic stem (ES) cells and genome sequence data. We identified seven medaka pluripotency genes by homology search and expression in vivo and in vitro. By RT-PCR analysis, the seven genes fall into three groups of expression pattern. Group I includes nanog and oct4 showing gonad-specific expression; Group II contains sall4 and zfp281 displaying gonad-preferential expression; Group III has klf4, ronin and tcf3 exhibiting expression also in several somatic tissues apart from the gonads. The transcripts of the seven genes are maternally supplied and persist at a high level during early embryogenesis. We made use of early embryos and adult gonads to examine expression in stem cells and differentiated derivatives by in situ hybridization. Strikingly, nanog and oct4 are highly expressed in pluripotent blastomeres of 16-cell embryos. In the adult testis, nanog expression was specific to spermatogonia, the germ stem cells, whereas tcf3 expression occurred in spermatogonia and differentiated cells. Most importantly, all the seven genes are pluripotency markers in vitro, because they have high expression in undifferentiated ES cells but dramatic down-regulation upon differentiation. Therefore, these genes have conserved their pluripotency-specific expression in vitro from mammals to lower vertebrates.
authors.affiliation: Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260.
authors.forename: Danke
authors.initials: D
authors.lastname: Wang
authors.forename: Dwarakanath
authors.initials: D
authors.lastname: Manali
authors.forename: Tiansu
authors.initials: T
authors.lastname: Wang
authors.forename: Narayani
authors.initials: N
authors.lastname: Bhat
authors.forename: Ni
authors.initials: N
authors.lastname: Hong
authors.forename: Zhendong
authors.initials: Z
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Rong
authors.initials: R
authors.lastname: Liu
authors.forename: Yunhan
authors.initials: Y
authors.lastname: Hong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001757:Blastomeres / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D005260:Female; D029941:Fish Proteins / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D009990:Oryzias / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D013737:Testis / Q000378:metabolism; D058125:Transcription Factor 7-Like 1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D029941:Fish Proteins; D018398:Homeodomain Proteins; D050814:Octamer Transcription Factor-3; D058125:Transcription Factor 7-Like 1 Protein