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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1992 Jul 1;89(13):5942–5945. doi: 10.1073/pnas.89.13.5942

Hormonal regulation of the thyrotropin beta-subunit gene by phosphorylation of the pituitary-specific transcription factor Pit-1.

H J Steinfelder 1, S Radovick 1, F E Wondisford 1
PMCID: PMC402114  PMID: 1321428

Abstract

The pituitary-specific transcription factor Pit-1 is a cell-specific activator of prolactin and growth hormone gene transcription in the anterior pituitary. Pit-1 has also been shown to mediate both thyrotropin-releasing hormone (TRH) and cAMP stimulation of the prolactin and thyrotropin beta-subunit (TSH beta) genes. The molecular mechanism by which Pit-1 mediates these stimulatory effects remains unclear. At least three Pit-1-binding elements within the TSH beta gene mediate responsiveness to TRH and cAMP. The present studies were designed to test the hypothesis that phosphorylation is an important modulator of Pit-1 interaction with the TSH beta gene. TSH beta elements bind less well to nonphosphorylated Pit-1 than to phosphorylated Pit-1 and are weak activators of gene expression, unlike high-affinity Pit-1 binding sites in the prolactin and growth hormone genes. Phosphorylation by protein kinase A or C enhances Pit-1 binding to TSH beta elements 3- to 8-fold. Conversely, phosphorylation generally reduces binding of Pit-1 to elements within the prolactin and growth hormone genes. A variation within the consensus sequence for Pit-1 binding in TSH beta gene elements [A(A/T)(A/T)AATNCAT in the TSH beta gene versus A(A/T)(A/T)TATNCAT in the prolactin and growth hormone genes] could explain these differences. These elements may limit basal activation of the TSH beta gene by binding less well to nonphosphorylated Pit-1 while conferring hormonal stimulation through enhanced binding of phosphorylated Pit-1.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bodenner D. L., Mroczynski M. A., Weintraub B. D., Radovick S., Wondisford F. E. A detailed functional and structural analysis of a major thyroid hormone inhibitory element in the human thyrotropin beta-subunit gene. J Biol Chem. 1991 Nov 15;266(32):21666–21673. [PubMed] [Google Scholar]
  2. Bodner M., Castrillo J. L., Theill L. E., Deerinck T., Ellisman M., Karin M. The pituitary-specific transcription factor GHF-1 is a homeobox-containing protein. Cell. 1988 Nov 4;55(3):505–518. doi: 10.1016/0092-8674(88)90037-2. [DOI] [PubMed] [Google Scholar]
  3. Bodner M., Karin M. A pituitary-specific trans-acting factor can stimulate transcription from the growth hormone promoter in extracts of nonexpressing cells. Cell. 1987 Jul 17;50(2):267–275. doi: 10.1016/0092-8674(87)90222-4. [DOI] [PubMed] [Google Scholar]
  4. Day R. N., Maurer R. A. The distal enhancer region of the rat prolactin gene contains elements conferring response to multiple hormones. Mol Endocrinol. 1989 Jan;3(1):3–9. doi: 10.1210/mend-3-1-3. [DOI] [PubMed] [Google Scholar]
  5. Elsholtz H. P., Albert V. R., Treacy M. N., Rosenfeld M. G. A two-base change in a POU factor-binding site switches pituitary-specific to lymphoid-specific gene expression. Genes Dev. 1990 Jan;4(1):43–51. doi: 10.1101/gad.4.1.43. [DOI] [PubMed] [Google Scholar]
  6. Ingraham H. A., Chen R. P., Mangalam H. J., Elsholtz H. P., Flynn S. E., Lin C. R., Simmons D. M., Swanson L., Rosenfeld M. G. A tissue-specific transcription factor containing a homeodomain specifies a pituitary phenotype. Cell. 1988 Nov 4;55(3):519–529. doi: 10.1016/0092-8674(88)90038-4. [DOI] [PubMed] [Google Scholar]
  7. Kapiloff M. S., Farkash Y., Wegner M., Rosenfeld M. G. Variable effects of phosphorylation of Pit-1 dictated by the DNA response elements. Science. 1991 Aug 16;253(5021):786–789. doi: 10.1126/science.1652153. [DOI] [PubMed] [Google Scholar]
  8. Li S., Crenshaw E. B., 3rd, Rawson E. J., Simmons D. M., Swanson L. W., Rosenfeld M. G. Dwarf locus mutants lacking three pituitary cell types result from mutations in the POU-domain gene pit-1. Nature. 1990 Oct 11;347(6293):528–533. doi: 10.1038/347528a0. [DOI] [PubMed] [Google Scholar]
  9. Nelson C., Albert V. R., Elsholtz H. P., Lu L. I., Rosenfeld M. G. Activation of cell-specific expression of rat growth hormone and prolactin genes by a common transcription factor. Science. 1988 Mar 18;239(4846):1400–1405. doi: 10.1126/science.2831625. [DOI] [PubMed] [Google Scholar]
  10. Peers B., Monget P., Nalda M. A., Voz M. L., Berwaer M., Belayew A., Martial J. A. Transcriptional induction of the human prolactin gene by cAMP requires two cis-acting elements and at least the pituitary-specific factor Pit-1. J Biol Chem. 1991 Sep 25;266(27):18127–18134. [PubMed] [Google Scholar]
  11. Shupnik M. A., Rosenzweig B. A., Showers M. O. Interactions of thyrotropin-releasing hormone, phorbol ester, and forskolin-sensitive regions of the rat thyrotropin-beta gene. Mol Endocrinol. 1990 Jun;4(6):829–836. doi: 10.1210/mend-4-6-829. [DOI] [PubMed] [Google Scholar]
  12. Simmons D. M., Voss J. W., Ingraham H. A., Holloway J. M., Broide R. S., Rosenfeld M. G., Swanson L. W. Pituitary cell phenotypes involve cell-specific Pit-1 mRNA translation and synergistic interactions with other classes of transcription factors. Genes Dev. 1990 May;4(5):695–711. doi: 10.1101/gad.4.5.695. [DOI] [PubMed] [Google Scholar]
  13. Steinfelder H. J., Hauser P., Nakayama Y., Radovick S., McClaskey J. H., Taylor T., Weintraub B. D., Wondisford F. E. Thyrotropin-releasing hormone regulation of human TSHB expression: role of a pituitary-specific transcription factor (Pit-1/GHF-1) and potential interaction with a thyroid hormone-inhibitory element. Proc Natl Acad Sci U S A. 1991 Apr 15;88(8):3130–3134. doi: 10.1073/pnas.88.8.3130. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Steinfelder H. J., Radovick S., Mroczynski M. A., Hauser P., McClaskey J. H., Weintraub B. D., Wondisford F. E. Role of a pituitary-specific transcription factor (pit-1/GHF-1) or a closely related protein in cAMP regulation of human thyrotropin-beta subunit gene expression. J Clin Invest. 1992 Feb;89(2):409–419. doi: 10.1172/JCI115600. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Theill L. E., Castrillo J. L., Wu D., Karin M. Dissection of functional domains of the pituitary-specific transcription factor GHF-1. Nature. 1989 Dec 21;342(6252):945–948. doi: 10.1038/342945a0. [DOI] [PubMed] [Google Scholar]
  16. Wondisford F. E., Farr E. A., Radovick S., Steinfelder H. J., Moates J. M., McClaskey J. H., Weintraub B. D. Thyroid hormone inhibition of human thyrotropin beta-subunit gene expression is mediated by a cis-acting element located in the first exon. J Biol Chem. 1989 Sep 5;264(25):14601–14604. [PubMed] [Google Scholar]
  17. Yan G. Z., Pan W. T., Bancroft C. Thyrotropin-releasing hormone action on the prolactin promoter is mediated by the POU protein pit-1. Mol Endocrinol. 1991 Apr;5(4):535–541. doi: 10.1210/mend-5-4-535. [DOI] [PubMed] [Google Scholar]

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