Endocrinology, Vol 134, 543-548, Copyright © 1994 by Endocrine Society

ARTICLES

Evidence that phosphorylation events participate in thyroid hormone action

KE Jones, JH Brubaker and WW Chin
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.

Using both a protein phosphatase inhibitor, okadaic acid (OA), and a protein kinase inhibitor, H7, to modify phosphorylation events in the cell, we investigated the effects of these agents on transcriptional activation via exogenous rat thyroid hormone receptor (TR) isoforms in transiently transfected cells and endogenous TRs. CV-1 cells were transiently cotransfected with expression plasmids encoding either the rat TR alpha 1 or TR beta 1, and luciferase reporter plasmids containing either the synthetic DR4 or the chick lysozyme F2 thyroid hormone response elements (TREs). For both receptor isoforms, there was an enhancement of transcriptional activity after incubation with 5 nM T3 for 24 h compared to hypothyroid levels. There was little change in transcriptional activation in the presence of 25 nM OA alone; however, for both TR isoforms and both TREs studied, OA augmented the stimulatory effects of T3. For the F2 TRE, transcriptional activation via TR alpha 1 increased from 19- to 35-fold, and that via TR beta 1 increased from 6- to 10-fold in the presence of T3 and OA compared to that with T3 alone. Similar results were found for the DR4 TRE. OA enhanced transcriptional activation by T3 in a dose-dependent manner. Increasing concentrations of OA (0, 5, 25, and 50 nM) further increased relative luciferase activity from 11-fold in the absence of OA to 45- fold in the presence of 50 nM OA. The protein kinase inhibitor, H7, caused no change in the transcriptional activity of the reporter plasmids via TR alpha 1 in the absence of T3, but completely blocked transcriptional activation by T3 for both the DR4 and the F2 TREs. H7 also blocked stimulation of endogenous GH and inhibition of endogenous TR beta 2 mRNAs by T3 in GH3 cells. These results indicate that phosphorylation events in the cell play an important role in transcriptional activation via both TR isoforms.

This article has been cited by other articles:

				X. Cao, F. Kambe, L. C. Moeller, S. Refetoff, and H. Seo Thyroid Hormone Induces Rapid Activation of Akt/Protein Kinase B-Mammalian Target of Rapamycin-p70S6K Cascade through Phosphatidylinositol 3-Kinase in Human Fibroblasts Mol. Endocrinol., January 1, 2005; 19(1): 102 - 112. [Abstract] [Full Text] [PDF]

				M. Kostrouchova, Z. Kostrouch, V. Saudek, J. Piatigorsky, and J. E. Rall BIR-1, a Caenorhabditis elegans homologue of Survivin, regulates transcription and development PNAS, April 29, 2003; 100(9): 5240 - 5245. [Abstract] [Full Text] [PDF]

				P. M. Yen Physiological and Molecular Basis of Thyroid Hormone Action Physiol Rev, July 1, 2001; 81(3): 1097 - 1142. [Abstract] [Full Text] [PDF]

				C. Tzagarakis-Foster and M. L. Privalsky Phosphorylation of Thyroid Hormone Receptors by Protein Kinase A Regulates DNA Recognition by Specific Inhibition of Receptor Monomer Binding J. Biol. Chem., May 1, 1998; 273(18): 10926 - 10932. [Abstract] [Full Text] [PDF]

				F. B. Hillgartner and T. Charron Glucose stimulates transcription of fatty acid synthase and malic enzyme in avian hepatocytes Am J Physiol Endocrinol Metab, March 1, 1998; 274(3): E493 - E501. [Abstract] [Full Text] [PDF]

				S. G. Ball, M. Ikeda, and W. W. Chin Deletion of the Thyroid Hormone {beta}1 Receptor Increases Basal and Triiodothyronine-Induced Growth Hormone Messenger Ribonucleic Acid in GH3 Cells Endocrinology, August 1, 1997; 138(8): 3125 - 3132. [Abstract] [Full Text] [PDF]

				W. Bai, B. G. Rowan, V. E. Allgood, B. W. O'Malley, and N. L. Weigel Differential Phosphorylation of Chicken Progesterone Receptor in Hormone-dependent and Ligand-independent Activation J. Biol. Chem., April 18, 1997; 272(16): 10457 - 10463. [Abstract] [Full Text] [PDF]

				P. S.-C. Wu, A. S. Moriscot, K. U. Knowlton, R. Hilal-Dandan, H. He, and W. H. Dillmann {alpha}1-Adrenergic Stimulation Inhibits 3,5,3'-Triiodothyronine-Induced Expression of the Rat Heart Sarcoplasmic Reticulum Ca2+ Adenosine Triphosphatase Gene Endocrinology, January 1, 1997; 138(1): 114 - 120. [Abstract] [Full Text] [PDF]

				D. C. Leitman, C. H.R.M. Costa, H. Graf, J. D. Baxter, and R. C.J. Ribeiro Thyroid Hormone Activation of Transcription Is Potentiated by Activators of cAMP-dependent Protein Kinase J. Biol. Chem., September 6, 1996; 271(36): 21950 - 21955. [Abstract] [Full Text] [PDF]

				P. J. Davis, A. Shih, H.-Y. Lin, L. J. Martino, and F. B. Davis Thyroxine Promotes Association of Mitogen-activated Protein Kinase and Nuclear Thyroid Hormone Receptor (TR) and Causes Serine Phosphorylation of TR J. Biol. Chem., November 22, 2000; 275(48): 38032 - 38039. [Abstract] [Full Text] [PDF]