, Volume 9, Issue 2, pp 143–152 | Cite as

Glucocorticoids modulate the biosynthesis and processing of proThyrotropin releasing-hormone (proTRH)

  • Thomas O. Bruhn
  • Susan S. Huang
  • Charles Vaslet
  • Eduardo A. Nillni


The thyrotropin- (TRH) releasing hormone precursor (26 kDa) undergoes proteolytic cleavage at either of two sites, generating N-terminal 15 kDa/9.5 kDa or C-terminal 16.5/10 kDa intermediate forms that are processed further to yield five copies of TRH-Gly and seven non-TRH peptides. Glucocorticoids (Gcc) have been shown to enhance TRH gene expression in three different cell systems in vitro, an effect that occurs, at least in part, through transcriptional activation. Although this implies that an increase of TRH prohormone biosynthesis would take place, this had not been demonstrated as yet. We report here that the synthetic glucocorticoid dexamethasone (Dex) substantially elevated the de novo biosynthesis of the intact 26-kDa TRH prohormone and its intermediate products of processing in cultured anterior pituitary cells, an observation that is consistent with an overall upregulation of both the biosynthesis and degradation of the TRH precursor. We reasoned that Gcc may act not only at the transcriptional, but also at the translational/posttranslational level. To address this question we chose a different cell system, AtT20 cells transfected with a cDNA encoding preproTRH. Since TRH gene expression in these cells is driven by the CMV-IE promoter and not by an endogenous “physiological” promoter, these cells provide an ideal model to study selectively the effects of Gcc on the translation and posttranslational processing of proTRH without interference from a direct transcriptional activation of the TRH gene. Dex caused a significant 75.7% increase in newly synthesized 26-kDa TRH prohormone, suggesting that the glucocorticoid raised the translation rate. We then demonstrated that Dex treatment accelerated TRH precursor processing. Of interest, processing of the N- vs the C-terminal intermediate was influenced differentially by the glucocorticoid. Although the N-terminal intermediate product of processing accumulated, the C-terminal intermediate was degraded more rapidly. Consistent with these observations was the finding that the intracellular accumulation of the N-terminally derived peptide preproTRH25–50 was enhanced, but levels of the C-terminally derived peptide preproTRH208–255 were reduced. Accumulation of TRH itself, whose five copies are N- and C-terminally derived, was also enhanced.

We conclude that Gcc induce changes in the biosynthesis and processing of proTRH by increasing the translation rate and by differentially influencing the processing of N- vs C-terminal intermediates of the precursor molecule. These effects of Gcc at the translational and posttranslational levels result in an increase in TRH production accompanied by differential effects on the accumulation of N- and C-terminal non-TRH peptides.

Key Words

AtT20 cells glucocorticoids peptide biosynthesis proTRH TRH 


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  1. 1.
    Lechan, R. M., Wu, P., Jackson, I. M. D., et al. (1986). Science 231, 159–161.PubMedCrossRefGoogle Scholar
  2. 2.
    Jackson, I. M. D. (1994). In: The Pituitary Gland, 2nd ed., Imura, H., ed., Raven: New York, pp. 179–216.Google Scholar
  3. 3.
    Bowers, C. Y., Friesen, H. G., Hwang, P., Guyda, H. J., and Folkers, K. (1971). Biochem. Biophys. Res. Commun. 45, 1033–1041.PubMedCrossRefGoogle Scholar
  4. 4.
    Wilber, J. F. and Utiger, R. D. (1967). Proc. Soc. Exp. Biol. Med. 127, 488–490.Google Scholar
  5. 5.
    Takahara, J., Arimura, A., and Schally, A. V. (1974). Proc. Soc. Exp. Biol. Med. 146, 831–835.PubMedGoogle Scholar
  6. 6.
    Lechan, R. M. (1993). Thyroid Today 16, 1–11.Google Scholar
  7. 7.
    Metcalf, G. (1974). Nature 252, 310–311.PubMedCrossRefGoogle Scholar
  8. 8.
    Hedner, J., Hedner, T., Jonason, J., and Lundberg, D. (1981). Neurosci. Lett. 24, 317–320.CrossRefGoogle Scholar
  9. 9.
    Sevarino, K. A., Goodman, R. H., Spiess, J., Jackson, I. M., and Wu, P. (1989). J. Biol. Chem. 264, 21,529–21,535.Google Scholar
  10. 10.
    Nillni, E. A., Sevarino, K. A., and Jackson, I. M. D. (1993). Endocrinology 132, 1260–1270.PubMedCrossRefGoogle Scholar
  11. 11.
    Perez de la Cruz, I. and Nillni, E. A. (1996). J. Biol. Chem. 271, 22,736–22,745.Google Scholar
  12. 12.
    Schaner, P., Todd, R. B., Seidah, N. G., and Nillni, E. A. (1997). J. Biol. Chem. 272, 19,958–19,968.CrossRefGoogle Scholar
  13. 13.
    Beato, M. (1989). Cell 56, 335–344.PubMedCrossRefGoogle Scholar
  14. 14.
    Yamamoto, K. R. (1985). Annu. Rev. Genet. 19, 209–252.PubMedCrossRefGoogle Scholar
  15. 15.
    O’Malley, B. (1990). Mol. Endocrinol. 4, 364–369.Google Scholar
  16. 16.
    Wahli, W. and Martinez, E. (1991). FASEB J. 5, 2243–2249.PubMedGoogle Scholar
  17. 17.
    Barg, J., Rius, R. A., Bem, W. T., Belcheva, M. M., Loh, Y. P., and Coscia, C. J. (1992). Brain Res. Dev. Brain Res. 66, 71–76.PubMedCrossRefGoogle Scholar
  18. 18.
    Birnberg, N. C., Lissitzky, J. C., Hinman, M., and Herbert E. (1983). Proc. Natl. Acad. Sci. USA 80, 6982–6986.PubMedCrossRefGoogle Scholar
  19. 19.
    Deschepper, C. F. and Flaxman, M. (1990). Endocrinology 126, 963–970.PubMedGoogle Scholar
  20. 20.
    Kovacs, K. J. and Mezey, E. (1987). Neuroendocrinology 46, 365–368.PubMedGoogle Scholar
  21. 21.
    Thiele, E. A., Marek, K. L., and Eipper, B. A. (1989). Endocrinology 125, 2279–2288.PubMedGoogle Scholar
  22. 22.
    Fuller, P. J. (1991). FASEB J. 5, 3092–3099.PubMedGoogle Scholar
  23. 23.
    Diamond, M. I., Miner, J. N., Yoshinage, S. K., and Yamamoto, K. R. (1990). Science 249, 1266–1272.PubMedCrossRefGoogle Scholar
  24. 24.
    Schule, R., Rangarajan, P., Kliewer, S., et al. (1990). Cell 62, 1217–1226.PubMedCrossRefGoogle Scholar
  25. 25.
    de Nadai, F., Rovere, C., Bidard, J. N., et al. (1993). Endocrinology 132, 1614–1620.PubMedCrossRefGoogle Scholar
  26. 26.
    Firestone, G. L., Payvar, F., and Yamamoto, K. R. (1982). Nature 300, 221–225.PubMedCrossRefGoogle Scholar
  27. 27.
    Goodman, L. J. and Firestone, G. L. (1993). Mol. Endocrinol. 7, 94–103.PubMedCrossRefGoogle Scholar
  28. 28.
    Haffar, O. K., Aponte, G. W., Bravo, D. A., John, N. J., Hess, R. T., and Firestone, G. L. (1988). J. Cell Biol. 106, 1463–1474.PubMedCrossRefGoogle Scholar
  29. 29.
    Poyet, P., Henning, S. J., and Rosen, J. M. (1989). Mol. Endocrinol. 3, 1961–1968.PubMedCrossRefGoogle Scholar
  30. 30.
    Shields, P. P., Dixon, J. E., and Glembotski, C. C. (1988). J. Biol. Chem. 263, 12,619–12,628.Google Scholar
  31. 31.
    Corey, J. L. and Stallcup, M. R. (1992). Mol. Endocrinol. 6, 450–458.PubMedCrossRefGoogle Scholar
  32. 32.
    Kain, S. R., Jen, T. I., and Firestone, G. L. (1993). J. Biol. Chem. 268, 19,640–19,649.Google Scholar
  33. 33.
    Platt, E. J., Goodman, L. J., Kain, S. R., Zettl, K. S., and Firestone, G. L. (1991). Mol. Endocrinol. 5, 1696–1706.PubMedGoogle Scholar
  34. 34.
    Luo, L., Bruhn, T. O., and Jackson, I. M. D. (1995). Endocrinology 136, 4945–4950.PubMedCrossRefGoogle Scholar
  35. 35.
    Bruhn, T. O., Rondeel, J. M., Bolduc, T. H., and Jackson, I. M. D. (1994). Endocrinology 134, 821–825.PubMedCrossRefGoogle Scholar
  36. 36.
    Tavianini, M. A., Gnokos, P. J., Lampe, T. H., and Ross, B. A. (1989). Mol. Endocrinol. 3, 605–610.PubMedGoogle Scholar
  37. 37.
    Bruhn, T. O., Bolduc, T. G., MacLean, D. B., and Jackson, I. M. D. (1991). Endocrinology 129, 556–558.PubMedCrossRefGoogle Scholar
  38. 38.
    Bruhn, T. O., Rondeel, J. M. M., Bolduc, T. G., and Jackson, I. M. D. (1994). Endocrinology 134, 815–820.PubMedCrossRefGoogle Scholar
  39. 39.
    Nillni, E. A., Sevarino, K. A., Wu, P., and Jackson, I. M. D. (1991). In: Methods in Neurosciences. Neuropeptide Technology, vol. 6., Conn, P. M., ed., Academic: New York, pp. 51–69.Google Scholar
  40. 40.
    Chomczynski, P. and Sacchi, N. (1987). Anal. Biochem. 162, 156–159.PubMedCrossRefGoogle Scholar
  41. 41.
    Selden, R. (1987). In: Current Protocols in Molecular Biology, Janssen, K., ed., Wiley: New York, pp. 4.9.1–4.9.7.Google Scholar
  42. 42.
    Nillni, E. A., Friedman, T. C., Todd, R. B., Birch, N. P., Loh, Y. P., and Jackson, I. M. D. (1995). J. Neurochem. 65, 2462–2472.PubMedCrossRefGoogle Scholar
  43. 43.
    Schagger, H. and Von Jagow, G. (1987). Annal. Biochem. 166, 368–379.CrossRefGoogle Scholar
  44. 44.
    Nillni, E. A., Luo, L. G., Jackson, I. M. D., and McMillan, P. (1996). Endocrinology 137, 5651–5661.PubMedCrossRefGoogle Scholar
  45. 45.
    Kakucska, I., Qi, Y., and Lechan, R. M. (1995). Endocrinology 136, 2795–2802.PubMedCrossRefGoogle Scholar
  46. 46.
    Cintra, A., Fuxe, K., Wilkstrom, A. C., Visser, T., and Gustafsson, J. A. (1990). Brain Res. 506, 139–141.PubMedCrossRefGoogle Scholar
  47. 47.
    Lee, S. L., Stewart, K., and Goodman, R. H. (1988). J. Biol. Chem. 263, 16,604–16,609.Google Scholar
  48. 48.
    Lee, S. L. and Sevarino, K. A. (1991). Methods Neurosci. 5, 34–44.Google Scholar
  49. 49.
    Friedman, T. C., Loh, Y. P., Huang, S. S., Jackson, I. M. D., and Nillni, E. A. (1995). Endocrinology 136, 4462–4472.PubMedCrossRefGoogle Scholar
  50. 50.
    Nillni, E. A., Sevarino, K. A., and Jackson, I. M. D. (1993). Endocrinology 132, 1271–1277.PubMedCrossRefGoogle Scholar
  51. 51.
    Bloomquist, B. T., Eipper, B. A., and Mains, R. E. (1991). Mol. Endocrinol. 5, 2014–2024.PubMedGoogle Scholar
  52. 52.
    Day, R., Schafer, M. K.-H., Watson, S. J., Chretien, M., and Seidah, N. G. (1992). Mol. Endocrinol. 6, 485–497.PubMedCrossRefGoogle Scholar
  53. 53.
    Nillni, E. A., Verdier, P. A., and Huang, S. H. (1995). Mol. Biol. Cell. 6(Abstract 1926), 331a.Google Scholar

Copyright information

© Humana Press Inc 1998

Authors and Affiliations

  • Thomas O. Bruhn
    • 2
  • Susan S. Huang
    • 1
  • Charles Vaslet
    • 1
  • Eduardo A. Nillni
    • 1
  1. 1.Division of Endocrinology, Department of MedicineBrown University School of Medicine, Rhode Island HospitalProvidence
  2. 2.Institut für Zellbiochemie und klinische NeurobiologieUniversität Hamburg (UKE)HamburgGermany

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