Type 1 iodothyronine deiodinase in the house musk shrew (Suncus murinus, Insectivora: Soricidae): cloning and characterization of complementary DNA, unique tissue distribution and regulation by T(3).
The house musk shrew Suncus murinus (Insectivora: Soricidae) has been reported as having low thyroxine to 3,3'5-triiodothyronine (T(3)) converting activity in liver and kidney homogenates and was assumed to be type 1 iodothyronine deiodinase (D1)-deficient. To study whether this is due to structural abnormality of shrew D1, we cloned the cDNA and characterized the enzyme. The deduced amino acid sequence of shrew D1 was found to be highly homologous to other known D1s and the enzyme itself to have similar catalytic activity. However, unlike in other species, the D1 activity was detected only in liver. Moreover, the D1 activity in liver of the shrew was less than half of that in rat liver and its expression was not up-regulated by T(3). In contrast, a very high activity of D2 was demonstrated in brain and brown adipose tissue. The present study also revealed that the serum level of T(3) in the shrew was in the same range as these in other mammals. These results suggest that D2 contributes to the production and maintenance of T(3) levels in the house musk shrew.
Rogatcheva
Margarita
M
Department of Teratology and Genetics, Division of Molecular and Cellular Adaptation, Research Institute of Environmental Medicine, Nagoya University, Japan.
Hayashi
Yoshitaka
Y
Oda
Sen
S
Seo
Hisao
H
Cua
Kevin
K
Refetoff
Samuel
S
Murakami
Masami
M
Mori
Masatomo
M
Murata
Yoshiharu
Y
D002001:Adipose Tissue, Brown / Q000201:enzymology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000737:chemistry; D002540:Cerebral Cortex / Q000201:enzymology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D019143:Evolution, Molecular; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007453:Iodide Peroxidase / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000201:enzymology; D012333:RNA, Messenger / Q000032:analysis; D011988:Receptors, Thyroid Hormone / Q000032:analysis; D012788:Shrews / Q000235:genetics* / Q000378:metabolism; D013961:Thyroid Gland / Q000201:enzymology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014018:Tissue Distribution; D014284:Triiodothyronine / Q000097:blood / Q000494:pharmacology*; D014285:Triiodothyronine, Reverse / Q000097:blood
D018076:DNA, Complementary; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013972:Thyrotropin; D007453:Iodide Peroxidase; D013974:Thyroxine