Identification of two novel splicing variants of human type II iodothyronine deiodinase mRNA.
Human type II iodothyronine deiodinase (hDII) belongs to a family of selenoproteins. It catalyzes 5'-deiodination of thyroxine to generate an active thyroid hormone, 3,3',5-triiodothyronine. Two novel splice variants of hDII gene transcript; namely hDII-b and hDII-c, were identified. Three distinct DNA fragments (hDII-a-c) were amplified by a reverse transcription-polymerase chain reaction (RT-PCR) with hDII intron-spanning primers using total-RNA from human umbilical vein endothelial cell line, ECV304. The sequence of hDII-a was identical to that of previously reported hDII. hDII-b and hDII-c had an additional insertion of 108 and 242 bp, respectively. The insertion sequences were found in the intron of hDII gene, therefore, two novel exons exist between exons 1 and 2 of hDII gene. The splice sites of new exons (b and c) conserved the consensus sequences of splice acceptor and donor sites. hDII-b contains exon b with an in-frame TGA codon that may encode an extra selenocysteine. hDII-c contained exons b and c and the predicted open reading frame is interrupted by a stop codon (TAA) produced by a frame shift. RT-PCR analysis showed that hDII-a and hDII-b mRNAs are expressed in human tissues including brain, kidney, lung and trachea. The mRNA abundance of hDII-c was lower than that of hDII-a or hDII-b. Thus, the new variants of hDII transcripts suggest the presence of two short exons between exons 1 and 2 of hDII gene, and of functional variant of hDII.
Ohba
K
K
Department of Pharmacology, Tokyo Women's Medical University, School of Medicine 8-1 Kawada-cho, Shinjuku-ku, 162-8666, Tokyo, Japan. ohba@research.twu.ac.jp
Yoshioka
T
T
Muraki
T
T
D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D005091:Exons; D014644:Genetic Variation; D006801:Humans; D007453:Iodide Peroxidase / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014018:Tissue Distribution; D000097564:Iodothyronine Deiodinase Type II
D007453:Iodide Peroxidase; D012333:RNA, Messenger; D000097564:Iodothyronine Deiodinase Type II