Type II iodothyronine deiodinase is preferentially expressed in rainbow trout (oncorhynchus mykiss) liver and gonads

• Published in: Molecular reproduction and development Vol. 60; no. 3; pp. 338 - 350
• Main Authors: Sambroni, Elisabeth, Gutieres, Stéphanie, Cauty, Chantal, Guiguen, Yann, Breton, Bernard, Lareyre, Jean-Jacques
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.11.2001; Wiley-Liss; Wiley
• Subjects: 3' Untranslated Regions; Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Cloning, Molecular; DNA, Complementary - genetics; Evolution, Molecular; Female; Fundamental and applied biological sciences. Psychology; Gene Expression; Hormone metabolism and regulation; Humans; Iodide Peroxidase - genetics; iodothyronine deiodinase; Iodothyronine Deiodinase Type II; Life Sciences; Liver - enzymology; Male; Mammalian male genital system; Mice; Molecular Sequence Data; Oncorhynchus mykiss; Oncorhynchus mykiss - genetics; Oncorhynchus mykiss - metabolism; Open Reading Frames; ovary; Ovary - enzymology; Promoter Regions, Genetic; Rats; Reproductive Biology; Restriction Mapping; RNA, Messenger - chemistry; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; spermatogenesis; Spermatogenesis - genetics; testis; Testis - enzymology; thyroxine; Tissue Distribution; Vertebrates: reproduction; Nucleotide sequence; Digestive system; Enzyme; Spermatogenesis; Liver; Gene expression; Oncorhynchus mykiss; Testicle; Male genital system; Vertebrata; Regulation(control); Thyroxine deiodinase; Gonad; Pisces; Thyroxine; Thyroid hormone; Hydrolases; Iodothyronine; Molecular cloning; GAMETOGENESE
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.1096

It is well admitted that thyroid hormones (TH) play a role in the development of vertebrates. The major secretory product of the thyroid is a pro‐hormone, T4, which is activated in peripheral tissues by outer ring deiodination to T3. We have isolated from rainbow trout testis, a full length cDNA encoding type II iodothyronine deiodinase (rtD2). The cDNA was 2410 nucleotides long and coded for a polypeptide of 264 amino acids including a selenocysteine residue. The predicted molecular weight of rtD2 was 29.3 kDa and the isoelectric point 8.71. The deduced amino acids sequence showed 80% identity with Fundulus heteroclitus D2 (fhD2) but only 68–69% identity with rat, mouse, and human D2. The 3′ UTR contained a putative selenocysteine insertion sequence (SECIS) similar to that described in human cDNA. The rtD2 gene was isolated and the gene structure was similar to that described in human with two exons separated by a large intron. We studied rtD2 gene expression by Northern blot analysis using total RNA extracted from testis, ovary, and other tissues. We found a high expression of a 3 kb transcript in liver and in gonads. A lower expression was also detected in posterior kidney. In testis, rtD2 mRNA expression was dependent on spermatogenic stages: it increased at the onset of spermatogenesis. Our results show that the structural characteristics of the D2 protein and gene have been highly conserved during evolution. The rtD2 mRNA expression in the gonads suggests that rtD2 may be a key factor regulating local supply of active T3 during rainbow trout gametogenesis. Mol. Reprod. Dev. 60: 338–350, 2001. © 2001 Wiley‐Liss, Inc.