title: Tissue-specific expression of a bHLH-PAS protein homologous to ARNT during the development of crustacean Daphnia magna.
abstract: cDNAs encoding a Daphnia magna homolog of aryl hydrocarbon receptor nuclear translocator (ARNT) were isolated and the structural and functional features as well as the expression pattern of their product, DmagARNT, were analyzed. Among the known bHLH-PAS proteins, the deduced amino acid sequences of DmagARNT showed the highest degree of identity to that of Drosophila ARNT (TGO). Expression of DmagARNT in ARNT-lacking mouse Hepa-c4 cells resulted in the compensation for the loss of hypoxia response, suggesting the formation of a dimer with mouse HIF-1alpha and that the resulting heterodimer binds to the hypoxia-responsive elements (HRE), leading to transcription of the downstream luciferase gene. Expression of D. magna ARNT was evident at the middle to late stages of embryonic development (about 25 h to 48 h after ovulation) in several tissues, including a pair of the 1st antenna, 2nd antenna, 2nd maxilla, five pairs of the thoracic limbs, the central nerve system, anus, dorsal organ, maxillary gland, and carapace. As observed in other species, the D. magna ARNT is likely to function broadly as an expressed dimerization partner in developmental processes. In contrast, expression of ARNT in adult D. magna was limited to the epipodites of thoracic limbs, suggesting that ARNT plays a role solely in hypoxia response in adult Daphnia.
authors.affiliation: Environmental Science Division, School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, Japan. shinichi@ls.toyaku.ac.jp
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Tokishita
authors.forename: Shoko
authors.initials: S
authors.lastname: Kimura
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Mandokora
authors.forename: Kagayaki
authors.initials: K
authors.lastname: Kato
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shiga
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ohta
authors.forename: Hideo
authors.initials: H
authors.lastname: Yamagata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000235:genetics / Q000378:metabolism; D020029:Base Pairing; D051792:Basic Helix-Loop-Helix Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000473:pathology; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D003621:Daphnia / Q000196:embryology*; D019281:Dimerization; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian; D017930:Genes, Reporter; D051793:Hypoxia-Inducible Factor 1 / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D018076:DNA, Complementary; D029721:Drosophila Proteins; D051793:Hypoxia-Inducible Factor 1; D019476:Insect Proteins; D008156:Luciferases; C497397:Arnt protein, mouse; C109766:tgo protein, Drosophila