title: Expression of type 2 iodothyronine deiodinase in corticotropin-secreting mouse pituitary tumor cells is stimulated by glucocorticoid and corticotropin-releasing hormone.
abstract: 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.
authors.affiliation: First Department of Internal Medicine, Gunma University School of Medicine, Maebashi 371-8511, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Araki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Morimura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ogiwara
authors.forename: Haruo
authors.initials: H
authors.lastname: Mizuma
authors.forename: Masatomo
authors.initials: M
authors.lastname: Mori
authors.forename: Masami
authors.initials: M
authors.lastname: Murakami
mesh_terms: 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
chemical_list: 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