This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by BJÖRKMAN, U. Articles by EKHOLM, R. Search for Related Content PubMed PubMed Citation Articles by BJÖRKMAN, U. Articles by EKHOLM, R.

Accelerated Exocytosis and H2O2 Generation in Isolated Thyroid Follicles Enhance Protein Iodination^*

Department of Anatomy, University of Goteborg Goteborg, Sweden

Address requests for reprints to: Dr. Ulla Bjorkman, Department of Anatomy, University of Goteborg, Box 33031, S-40033 Goteborg, Sweden.

Abstract

Open pig thyroid follicles in which the apical surface of the follicle cells is in direct contact with the incubation medium were used to study the effect of stimulated exocytosis and stimulated H₂O₂ generation on the iodination of protein in the incubation medium. In previous studies on this system of follicles we have shown (1) that the apical surface of the follicle cells is a major site of protein iodination and (2), that H₂O₂ is produced at the apical cell surface.

In the present study we confirmed the previous finding that H₂O₂ generation is greatly stimulated by the Ca²⁺ ionophore A23187. We further found that TSH at a high concentration (>10 mU/ml) and in the presence of Ca²⁺ stimulated H₂O₂ generation; TSH had no such effect on follicles incubated in Ca²⁺-free medium after pretreatment with EGTA. Forskolin did not stimulate H₂O₂ generation. Exocytosis of thyroglobulin was stimulated by TSH at a low concentration (0.1 mU/ml), and this stimulation was not dependent on Ca²⁺. Exocytosis was also stimulated by forskolin but not by A23187. Iodination of protein, including thyroglobulin, in the incubation medium was stimulated by A23187, TSH and forskolin.

These observations suggest that stimulation of iodination in association with the apical surface of the follicle cells can be achieved separately by an increased rate of H₂O₂ generation and increased rate of exocytosis. Generation of H₂O₂ is Ca²⁺-dependent, whereas exocytosis is mediated by the adenylate cyclasecAMP system; TSH at a high concentration can stimulate both these processes. (Endocrinology 122: 488–494, 1988)

Footnotes

^* This work was supported by grants from the Swedish Medical Research council (Grant 12X-537) and Axel and Margaret Ax:son Johnson’s Foundation (Stockholm).

Received April 29, 1987.

This article has been cited by other articles:

				N. Driessens, S. Versteyhe, C. Ghaddhab, A. Burniat, X. De Deken, J. Van Sande, J.-E. Dumont, F. Miot, and B. Corvilain Hydrogen peroxide induces DNA single- and double-strand breaks in thyroid cells and is therefore a potential mutagen for this organ Endocr. Relat. Cancer, September 1, 2009; 16(3): 845 - 856. [Abstract] [Full Text] [PDF]

				L. Ulianich, M. G. Elia, A. S. Treglia, A. Muscella, B. Di Jeso, C. Storelli, and S. Marsigliante The sarcoplasmic-endoplasmic reticulum Ca2+ ATPase 2b regulates the Ca2+ transients elicited by P2Y2 activation in PC Cl3 thyroid cells. J. Endocrinol., September 1, 2006; 190(3): 641 - 649. [Abstract] [Full Text] [PDF]

				M.-C. Nlend, D. M. Cauvi, N. Venot, and O. Chabaud Role of Sulfated Tyrosines of Thyroglobulin in Thyroid Hormonosynthesis Endocrinology, November 1, 2005; 146(11): 4834 - 4843. [Abstract] [Full Text] [PDF]

				L. E. Ericson and M. Nilsson Deactivation of TSH receptor signaling in filter-cultured pig thyroid epithelial cells Am J Physiol Endocrinol Metab, April 1, 2000; 278(4): E611 - E619. [Abstract] [Full Text] [PDF]

				D Prabakaran, R. Ahima, J. Harney, M. Berry, P. Larsen, and P Arvan Polarized targeting of epithelial cell proteins in thyrocytes and MDCK cells J. Cell Sci., January 4, 1999; 112(8): 1247 - 1256. [Abstract] [PDF]

				R. Kuliawat, M. P. Lisanti, and P. Arvan Polarized Distribution and Delivery of Plasma Membrane Proteins in Thyroid Follicular Epithelial Cells J. Biol. Chem., February 10, 1995; 270(6): 2478 - 2482. [Abstract] [Full Text] [PDF]