title: Identification and functional characterization of an alternative splice variant within the fourth exon of human nanog.
abstract: Nanog, a homeodomain (HD) transcription factor, plays a critical role in the maintenance of embryonic stem (ES) cell self-renewal. Here, we report the identification of an alternatively-spliced variant of nanog. This variant lacked a stretch of amino acids (residues 168-183) located between the HD and tryptophan-repeat (WR) of the previously-reported full length sequence, suggesting that the deleted sequence functions as a linker and possibly affects the flexibility of the C-terminal transactivation domain relative to the DNA binding domain. Expression of mRNA encoding the splice variant, designated as nanog-delta 48, was much lower than that of the full length version in human ES cells. The ratio of nanog-delta 48 transcript to full length transcript increased, however, in multipotent adult progenitor cells. EMSA analysis revealed that both forms of Nanog were able to bind a nanog binding sequence with roughly the same affinity. A reporter plasmid assay also showed that both variants of nanog modestly repressed transactivation of gata-4, whose expression is proposed to be inhibited by nanog, with comparable potency. We conclude that, despite the difference in primary structure and expression pattern in various stem cells, the alternatively-spliced variant of Nanog has similar activity to that of the full length version.
authors.affiliation: Division of Molecular and Life Sciences, College of Science and Technology, Hanyang University, Seoul 133-791, Korea.
authors.forename: Jung Sun
authors.initials: JS
authors.lastname: Kim
authors.forename: Jiha
authors.initials: J
authors.lastname: Kim
authors.forename: Byung Soo
authors.initials: BS
authors.lastname: Kim
authors.forename: Hee Yong
authors.initials: HY
authors.lastname: Chung
authors.forename: Young Yiul
authors.initials: YY
authors.lastname: Lee
authors.forename: Choon Sik
authors.initials: CS
authors.lastname: Park
authors.forename: Young Seek
authors.initials: YS
authors.lastname: Lee
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Il Yup
authors.initials: IY
authors.lastname: Chung
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005091:Exons / Q000235:genetics*; D050991:GATA4 Transcription Factor / Q000378:metabolism; D020869:Gene Expression Profiling; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D000071317:Nanog Homeobox Protein; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D012333:RNA, Messenger