Expression of type 2 iodothyronine deiodinase in corticotropin-secreting mouse pituitary tumor cells is stimulated by glucocorticoid and corticotropin-releasing hormone.
We identified the presence of iodothyronine deiodinase in AtT-20 mouse pituitary tumor cells that secrete corticotropin. Iodothyronine deiodinating activity in AtT-20 cells fulfills all the characteristics of type 2 iodothyronine deiodinase (D2), including the inhibition by thyroid hormones, the insensitivity to inhibition by 6-propyl-2-thiouracil, and the low Michaelis-Menten constant value for T4. Northern analysis using mouse D2 cRNA probe demonstrated the hybridization signal of approximately 7.0 kb in size in AtT-20 cells. D2 activity and D2 mRNA were stimulated by glucocorticoid in a dose-dependent manner but were not stimulated by testosterone or beta-estradiol. D2 expression was stimulated by (Bu)2cAMP, and CRH in a dose-dependent manner in the presence of dexamethasone. These results suggest the previously unrecognized role of local thyroid hormone activation by D2 in the regulation of pituitary corticotrophs.
Araki
Osamu
O
First Department of Internal Medicine, Gunma University School of Medicine, Maebashi 371-8511, Japan.
Morimura
Tadashi
T
Ogiwara
Takayuki
T
Mizuma
Haruo
H
Mori
Masatomo
M
Murakami
Masami
M
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage*; D000242:Cyclic AMP / Q000494:pharmacology; D003907:Dexamethasone / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000008:administration & dosage*; D007453:Iodide Peroxidase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010911:Pituitary Neoplasms / Q000201:enzymology* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D013256:Steroids / Q000494:pharmacology; D013963:Thyroid Hormones / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D000097564:Iodothyronine Deiodinase Type II
D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D003907:Dexamethasone; D005938:Glucocorticoids; D007453:Iodide Peroxidase; D012333:RNA, Messenger; D013256:Steroids; D013963:Thyroid Hormones; D000097564:Iodothyronine Deiodinase Type II