Endocrinology, Vol 136, 1488-1494, Copyright © 1995 by Endocrine Society

ARTICLES

Pituitary cells respond to thyroid hormone by discrete, gene-specific pathways

AL Maia, JW Harney and PR Larsen
Thyroid Division, Brigham and Women's Hospital, Boston, Massachusetts 02115.

Type 1 iodothyronine deiodinase (D1) converts T4 to T3, the active thyroid hormone, by removal of the outer ring iodine. Previous studies in liver and thyroid cells have shown that T3 regulates Type 1 deiodinase (dio1) gene expression by a mechanism not requiring ongoing protein synthesis. For certain T3-regulated genes, such as rat GH, T3- induced transcription is blocked by protein synthesis inhibitors. Because the somatotrope tumor cell lines express both dio1 and GH, we compared these two positively T3-regulated genes to establish whether cycloheximide blockade of T3 effects is cell-type or gene specific. In these cells, the T3 stimulation of dio1 messenger RNA (mRNA) is not blocked by cycloheximide, whereas the T3 effect on GH mRNA synthesis is eliminated. Other differences between these two genes were also noted. Retinoic acid does not alter dio1 gene expression or the response to T3 but increases GH and synergizes with T3. Dexamethasone alone had no effect on dio1 mRNA but did enhance the effect of T3 on both dio1 and GH. These results point to distinct pathways for T3 induction of mRNA synthesis from different genes within the same cell.

This article has been cited by other articles:

				H. Ohguchi, T. Tanaka, A. Uchida, K. Magoori, H. Kudo, I. Kim, K. Daigo, I. Sakakibara, M. Okamura, H. Harigae, et al. Hepatocyte Nuclear Factor 4{alpha} Contributes to Thyroid Hormone Homeostasis by Cooperatively Regulating the Type 1 Iodothyronine Deiodinase Gene with GATA4 and Kruppel-Like Transcription Factor 9 Mol. Cell. Biol., June 15, 2008; 28(12): 3917 - 3931. [Abstract] [Full Text] [PDF]

				M. S Wagner, S. M Wajner, J. M Dora, and A. L. Maia Regulation of Dio2 gene expression by thyroid hormones in normal and type 1 deiodinase-deficient C3H mice J. Endocrinol., June 1, 2007; 193(3): 435 - 444. [Abstract] [Full Text] [PDF]

				J. Kohrle, F. Jakob, B. Contempre, and J. E. Dumont Selenium, the Thyroid, and the Endocrine System Endocr. Rev., December 1, 2005; 26(7): 944 - 984. [Abstract] [Full Text] [PDF]

				S Van der Geyten and V M Darras Developmentally defined regulation of thyroid hormone metabolism by glucocorticoids in the rat J. Endocrinol., May 1, 2005; 185(2): 327 - 336. [Abstract] [Full Text] [PDF]

				A. M. Zavacki, H. Ying, M. A. Christoffolete, G. Aerts, E. So, J. W. Harney, S.-y. Cheng, P. R. Larsen, and A. C. Bianco Type 1 Iodothyronine Deiodinase Is a Sensitive Marker of Peripheral Thyroid Status in the Mouse Endocrinology, March 1, 2005; 146(3): 1568 - 1575. [Abstract] [Full Text] [PDF]

				A. C. Bianco, D. Salvatore, B. Gereben, M. J. Berry, and P. R. Larsen Biochemistry, Cellular and Molecular Biology, and Physiological Roles of the Iodothyronine Selenodeiodinases Endocr. Rev., February 1, 2002; 23(1): 38 - 89. [Abstract] [Full Text] [PDF]

				S.-W. Kim, J. W. Harney, and P. R. Larsen Studies of the Hormonal Regulation of Type 2 5'-Iodothyronine Deiodinase Messenger Ribonucleic Acid in Pituitary Tumor Cells Using Semiquantitative Reverse Transcription-Polymerase Chain Reaction Endocrinology, December 1, 1998; 139(12): 4895 - 4905. [Abstract] [Full Text] [PDF]

				A. Baur, K. Bauer, H. Jarry, and J. Kohrle 3,5-Diiodo-L-Thyronine Stimulates Type 1 5'Deiodinase Activity in Rat Anterior Pituitaries in Vivo and in Reaggregate Cultures and GH3 Cells in Vitro Endocrinology, August 1, 1997; 138(8): 3242 - 3248. [Abstract] [Full Text] [PDF]

				H. F. Escobar-Morreale, M. J. Obregon, A. Hernandez, F. Escobar del Rey, and G. Morreale de Escobar Regulation of Iodothyronine Deiodinase Activity as Studied in Thyroidectomized Rats Infused with Thyroxine or Triiodothyronine Endocrinology, June 1, 1997; 138(6): 2559 - 2568. [Abstract] [Full Text] [PDF]