Hormonal regulation of some steps of thyroglobulin synthesis and secretion in bicameral cell culture

Desruisseau, Sylvie; Alquier, Christian; Depétris, D.; Gruffat, Dominique; Chabaud, Odile

doi:10.1002/jcp.1041600215

Cited by 4 publications

(2 citation statements)

References 40 publications

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“…TSH and iodide were also found to regulate the cytosolic volumes and the total amount of proteins without affecting the number of cells. In the absence of iodide, the absolute cytosolic volume increased, but its proportion vs. the total cell volume decreased, showing an increase in the protein content when TSH stimulation was applied alone, partly by increasing the endoplasmic reticulum and the intracellular organelles (10,31). In the absence of TSH but with iodide, the decrease in protein content was associated with an increase in the absolute cytosolic volume and its proportion vs. the total cell volume.…”

Section: Discussionmentioning

confidence: 99%

Regulation of thyroid cell volumes and fluid transport: opposite effects of TSH and iodide on cultured cells

Cauvi

Penel

Nlend

et al. 2000

American Journal of Physiology-Endocrinology and Metabolism

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Cell volume regulation by thyrotropin (TSH) and iodide, the main effectors involved in thyroid function, was studied in cultured thyroid cells. The mean cell volume, determined by performing 3-D reconstitution on confocal microscopy optical slices from living octadecylrhodamine-labeled cells cultured with both TSH and iodide (control cells), was 3.73 +/- 0.06 pl. The absence of iodide resulted in cell hypertrophy (136% of control value) and the absence of TSH in cell shrinkage (81%). These changes mainly affected the cell heights. The effect of TSH on cell volume was mediated by cAMP. The proportion of cytosolic volume (3-O-methyl-D-glucose space vs. total volume) decreased in the absence of iodide (85% of control value) and increased in the absence of TSH (139%), whereas protein content showed the opposite changes (121 and 58%, respectively). The net apical-to-basal fluid transport was also inversely controlled by the two effectors. Iodide thus antagonizes TSH effects on cell volumes and fluid transport, probably via adenylylcyclase downregulation mechanisms. The absence of either iodide or TSH may mimic the imbalance occurring in pathological thyroids.

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Section: Discussionmentioning

confidence: 99%

Regulation of thyroid cell volumes and fluid transport: opposite effects of TSH and iodide on cultured cells

Cauvi

Penel

Nlend

et al. 2000

American Journal of Physiology-Endocrinology and Metabolism

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“…Over many years, we have accumulated extensive data on this culture system, which simulates thyroid metabolism in vivo, up to the stage of secretion of thyroid hormones into the basal medium (unpublished results). We have shown that TSH controlled all the steps of thyroglobulin metabolism that we have studied: thyroglobulin expression and secretion (25)(26)(27)(28), and two post-translational modifications, glycosylation (29,30) and iodination (31).…”

Section: Introductionmentioning

confidence: 99%

Thyrotropin regulates tyrosine sulfation of thyroglobulin

Nlend

Cauvi

Venot

et al. 1999

European Journal of Endocrinology

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Objective: To study the regulation of thyroglobulin sulfation by thyrotropin (TSH) and iodide. Sulfation, a widespread post-translational modification of proteins, is involved in various biological activities. Thyroglobulin has been reported to be sulfated but, to date, the role of sulfate residues in the metabolism and function of thyroglobulin is not known; moreover, the regulation of thyroglobulin sulfation has not been yet investigated. Methods: The effect of TSH on thyroglobulin sulfation was studied in porcine thyroid cells cultured on porous collagen-coated filters. Cells cultured with or without TSH and with or without iodide (KI) were incubated for 4 days with radioactive sulfate. The specific radioactivity of thyroglobulin subunit (330 kDa) was determined from apical media analyzed by electrophoresis. Enzymatic hydrolysates of the purified thyroglobulin were separated by oligosaccharide affinity chromatography and thin-layer chromatography; alkaline hydrolysates were analyzed only by thin-layer chromatography. Results: Thyroglobulin secreted by TSH-stimulated cells incorporated about twofold less radioactive sulfate. Iodide slightly modified this incorporation. Enzymatic hydrolysates of purified thyroglobulin showed sulfate residues bound essentially to complex oligosaccharide units. Alkaline hydrolysis was necessary to release all sulfated amino acids (tyrosine and serine). In the absence of TSH the proportion of tyrosine sulfate was dramatically increased: 24% compared with 7% (+KI) or 5% (¹KI). The ratio of specific radioactivity of thyroglobulin to the specific radioactivity of intracellular inorganic sulfate (determined in each culture condition) gave the number of sulfated residues incorporated: 46 (¹TSH) and 31 (+TSH) per mol thyroglobulin. From this distribution, we deduced the number of residues bound to complex oligosaccharide units and to tyrosine. Thus TSH decreased the number of sulfate residues on tyrosine from 11 to 2 per mol thyroglobulin. Conclusions: TSH regulates the binding of sulfate groups to tyrosine residues. Iodide exerts a slight control over this process.

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Thyrotropin chronically regulates the pool of thyroperoxidase and its intracellular distribution: A quantitative confocal microscopic study

Penel¹,

Gruffat²,

Alquier³

et al. 1998

J. Cell. Physiol.

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The regulation of thyroperoxidase (TPO) expression and of its intracellular distribution was studied in porcine thyroid cells cultured on porous bottom filters. Cells were cultured for 18 days in the absence or in the presence of thyrotropin (TSH) and with or without iodide. Microsomes were purified and analyzed by electrophoresis. TPO was detected by immunoblotting with polyclonal anti-porcine TPO antibodies and quantified by scanning the bands. The amount of TPO was increased 2-fold by TSH. High concentrations of iodide (1-50 microM, added daily) decreased the level of TPO. Confocal microscopy served to determine the intracellular localization of TPO and its quantitative distribution. Intracellular and surface-located TPO was detected by fluorescein-labeled antibodies on saponin-treated cells. Quantitative confocal microscopy showed that TSH increased the total amount of TPO 2-fold as for immunoblotting. The highest amount of TPO was found in the perinuclear area and between the nucleus and the Golgi apparatus. Only 4% of TPO was present on the apical surface and about 1% on the basolateral membrane; the remainder (about 95%) was inside the cells. TSH did not change these relative contents. TSH modified the intracellular distribution of the enzyme, increasing the TPO pool from the perinuclear area to apical membrane. This domain could be a site of storage of TPO. Adding a physiological concentration of iodide (0.5 microM, daily) did not influence the intracellular distribution of TPO. We concluded that chronic TSH stimulation 1) increased 2-fold the pool of TPO but did not change the relative proportion of TPO inside the cells and on the apical surface, and 2) modified the intracellular distribution of vesicular TPO, the major part of which was accumulated in the perinuclear and cytoplasmic area under the subapical domain of the polarized cells.

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Hormonal regulation of some steps of thyroglobulin synthesis and secretion in bicameral cell culture

Cited by 4 publications

References 40 publications

Regulation of thyroid cell volumes and fluid transport: opposite effects of TSH and iodide on cultured cells

Regulation of thyroid cell volumes and fluid transport: opposite effects of TSH and iodide on cultured cells

Thyrotropin regulates tyrosine sulfation of thyroglobulin

Thyrotropin chronically regulates the pool of thyroperoxidase and its intracellular distribution: A quantitative confocal microscopic study

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