title: Molecular characterization and sex-related seasonal expression of thyroid receptor subtypes in goldfish.
abstract: The thyroid hormones, acting through the nuclear thyroid receptors (TRs), play important roles in the growth and development of vertebrates. The present study investigated the molecular structure and season-related expression of the TR isoforms in the male and female goldfish pituitary, brain, liver, gonads, gut, heart, and muscle. Based on sequence alignment with other species, the results demonstrate the presence of: (1) a TRalpha (TRalpha-1) consisting of 1496 nucleotides encoding a 466 amino acid protein, (2) a novel splice variant of TRalpha (TRalpha-2) containing an out-of-frame deletion of 246 nucleotides in the ligand-binding domain consisting of 1251 nucleotides encoding a 378 amino acid protein, (3) a novel transcript resembling TRalpha, except for non-homology in the hinge region and a premature stop codon prior to the ligand-binding domain (TRalpha-truncated; 1418 nucleotides, 206 amino acid protein), and (4) TRbeta consisting of 1823 nucleotides encoding a 395 amino acid protein. The findings provide the first demonstration of the presence of a truncated TR isoform in non-mammalian vertebrates. In goldfish, the expression patterns for all TRs subtypes were found to be remarkably similar in both male and female, changing significantly before and during reproductive season. The results provide a frame work for better understanding of the functional significance of novel TR forms and TR subtypes in fish and other vertebrates.
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alta., Canada T3B 2V4.
authors.forename: E R
authors.initials: ER
authors.lastname: Nelson
authors.forename: H R
authors.initials: HR
authors.lastname: Habibi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005260:Female; D005786:Gene Expression Regulation; D014644:Genetic Variation; D006054:Goldfish / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000145:classification / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D012621:Seasons; D016415:Sequence Alignment; D012727:Sex Characteristics; D012737:Sex Factors; D037021:Thyroid Hormone Receptors alpha / Q000235:genetics
chemical_list: D020033:Protein Isoforms; D011988:Receptors, Thyroid Hormone; D037021:Thyroid Hormone Receptors alpha