help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bockmann, J.
Right arrow Articles by Kreutz, M. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bockmann, J.
Right arrow Articles by Kreutz, M. R.
Endocrinology Vol. 138, No. 3 1019-1028
Copyright © 1997 by The Endocrine Society

Articles

Thyrotropin Expression in Hypophyseal Pars Tuberalis-Specific Cells is 3,5,3'-Triiodothyronine, Thyrotropin-Releasing Hormone, and Pit-1 Independent1

J. Bockmann2, T. M. Böckers2, C. Winter, W. Wittkowski, H. Winterhoff, Th. Deufel3 and M. R. Kreutz

Institute of Anatomy, AG Molecular Neuroendocrinology (J.B., T.M.B., C.W., W.W.), the Institute of Pharmacology and Toxicology (H.W.), and the Department of Pediatrics (C.W., Th.D.), University of Münster, Münster; and AG Mol Cell Neurobiology, Institute of Medical Psychology, University of Magdeburg (M.R.K.), Magdeburg, Germany

Address all correspondence and requests for reprints to: Prof. Dr. W. Wittkowski, AG Molecular Neuroendocrinology, Institute of Anatomy, Vesaliusweg 2–4, D-48149 Münster, Germany. E-mail: bockers{at}uni-muenster.de

The expression of TSH subunit genes (TSH{alpha} and -ß) in pituitary thyrotropes is primarily regulated via circulating thyroid hormone levels (T3) and the hypothalamic TRH. Hypophyseal pars tuberalis (PT)-specific cells also express both hormonal subunits of TSH, but do not resemble thyrotropes of the pars distalis (PD) with respect to their distinct morphology, secretion, and direct modulation of TSH expression by photoperiodic inputs and melatonin. To investigate whether this distinct regulation of TSH is related to a different molecular structure or different signaling cascades, we analyzed PT-specific TSH and its transcriptional regulation in ovine PT-specific cells. After construction of PT- and PD-specific complementary DNA (cDNA) libraries, the cloning and sequencing of several TSH{alpha} and -ß subunit clones revealed identical sizes and sequences for the translated and untranslated regions in both hypophyseal compartments. Transcription start site analysis also displayed three identical start sites for the transcription of TSHß in PT and PD. After cloning of the ovine TRH receptor cDNA and a partial T3 receptor cDNA, in situ hybridization, Northern blot analysis, and PCR experiments showed that TRH and T3 receptors are not expressed in specific cells of the PT. The transcription factor Pit-1 that is involved in TSH expression of thyrotropes could only be detected in the PD.

In additional experiments rats were treated with T4 or TRH, and subsequent in situ hybridization studies showed that TSHß messenger RNA (mRNA) formation was not altered in the PT. In the PD, however, TSHß mRNA was significantly reduced in the T4-treated group, but was enhanced in the TRH-treated group. We conclude that PT-specific cells of the pituitary are characterized by the transcription of TSH subunits that are identical to TSH expressed in thyrotropes of the PD. The absence of TRH, T3 receptor mRNA, and Pit-1, respectively, as well as the different reactions compared to PD thyrotropes in in vivo experiments lead to the conclusion that the expression of TSH in PT-specific cells of the pituitary is not regulated via the classical thyrotrope receptors and their intracellular pathways, but through a novel, photoperiod-dependent mechanism.




This article has been cited by other articles:


Home page
 ReproductionHome page
N. Nakao, H. Ono, and T. Yoshimura
Thyroid hormones and seasonal reproductive neuroendocrine interactions
Reproduction, July 1, 2008; 136(1): 1 - 8.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
J. D. Johnston, S. Messager, F. J. P. Ebling, L. M. Williams, P. Barrett, and D. G. Hazlerigg
Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland
PNAS, March 4, 2003; 100(5): 2831 - 2835.
[Abstract] [Full Text] [PDF]

Home page
 J. Histochem. Cytochem.Home page
P. Klosen, C. Bienvenu, O. Demarteau, H. Dardente, H. Guerrero, P. Pevet, and M. Masson-Pevet
The mt1 Melatonin Receptor and ROR{beta} Receptor Are Co-localized in Specific TSH-immunoreactive Cells in the Pars Tuberalis of the Rat Pituitary
J. Histochem. Cytochem., December 1, 2002; 50(12): 1647 - 1657.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
B. Yusta, E. T. Alarid, D. F. Gordon, E. C. Ridgway, and P. L. Mellon
The Thyrotropin {beta}-Subunit Gene Is Repressed by Thyroid Hormone in a Novel Thyrotrope Cell Line, Mouse T{alpha}T1 Cells
Endocrinology, November 1, 1998; 139(11): 4476 - 4482.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
T. M. Bockers, J. Bockmann, A. Salem, P. Niklowitz, A. Lerchl, M. Huppertz, W. Wittkowski, and M. R. Kreutz
Initial Expression of the Common {alpha}-Chain in Hypophyseal Pars Tuberalis-Specific Cells in Spontaneous Recrudescent Hamsters
Endocrinology, October 1, 1997; 138(10): 4101 - 4108.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals
Copyright © 1997 by The Endocrine Society