title: Discovery of osmotic sensitive transcription factors in fish intestine via a transcriptomic approach.
abstract: BACKGROUND
  Teleost intestine is crucial for seawater acclimation by sensing osmolality of imbibed seawater and regulating drinking and water/ion absorption. Regulatory genes for transforming intestinal function have not been identified. A transcriptomic approach was used to search for such genes in the intestine of euryhaline medaka.
  
  
  RESULTS
  Quantitative RNA-seq by Illumina Hi-Seq Sequencing method was performed to analyze intestinal gene expression 0 h, 1 h, 3 h, 1 d, and 7 d after seawater transfer. Gene ontology (GO) enrichment results showed that cell adhesion, signal transduction, and protein phosphorylation gene categories were augmented soon after transfer, indicating a rapid reorganization of cellular components and functions. Among >50 transiently up-regulated transcription factors selected via co-expression correlation and GO selection, five transcription factors, including CEBPB and CEBPD, were confirmed by quantitative PCR to be specific to hyperosmotic stress, while others were also up-regulated after freshwater control transfer, including some well-known osmotic-stress transcription factors such as SGK1 and TSC22D3/Ostf1. Protein interaction networks suggest a high degree of overlapping among the signaling of transcription factors that respond to osmotic and general stresses, which sheds light on the interpretation of their roles during hyperosmotic stress and emergency.
  
  
  CONCLUSIONS
  Since cortisol is an important hormone for seawater acclimation as well as for general stress in teleosts, emergency and osmotic challenges could have been evolved in parallel and resulted in the overlapped signaling networks. Our results revealed important interactions among transcription factors and offer a multifactorial perspective of genes involved in seawater acclimation.
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan. martywong@aori.u-tokyo.ac.jp.
authors.forename: Marty Kwok-Shing
authors.initials: MK
authors.lastname: Wong
authors.forename: Haruka
authors.initials: H
authors.lastname: Ozaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Wataru
authors.initials: W
authors.lastname: Iwasaki
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takei
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D029941:Fish Proteins / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry; D020869:Gene Expression Profiling; D063990:Gene Ontology; D007413:Intestinal Mucosa / Q000378:metabolism*; D009990:Oryzias / Q000235:genetics* / Q000378:metabolism*; D009995:Osmosis; D025941:Protein Interaction Mapping; D012623:Seawater / Q000737:chemistry; D014157:Transcription Factors / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D029941:Fish Proteins; D014157:Transcription Factors