Thyrotrophin and cyclic AMP regulation of thyroglobulin gene expression in cultured porcine thyroid cells

Chabaud, Odile; Chambard, Marianne; Gaudry, N.; Mauchamp, Jean

doi:10.1677/joe.0.1160025

Cited by 30 publications

(16 citation statements)

References 25 publications

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“…Expression of the Tg and TPO genes is restricted to thyroid tissue (4) and is under hormonal control. The pituitary hormone TSH, via cAMP, insulin, and insulinlike growth factor I (IGF-I) exerts a positive effect on Tg (5)(6)(7)(8)(9) and TPO (10 -14) gene expression. The hormonal regulation mechanism of Tg and TPO promoter activities has been studied extensively in the last few years, since their promoters are well characterized (15,16).…”

mentioning

confidence: 99%

Transcriptional Control of the Forkhead Thyroid Transcription Factor TTF-2 by Thyrotropin, Insulin, and Insulin-like Growth Factor I

Ortíz¹,

Zannini²,

Lauro³

et al. 1997

Journal of Biological Chemistry

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The hormonal regulation of both thyroglobulin and thyroperoxidase promoter activity in FRTL-5 thyroid cells takes place, at least in part, through a hormoneresponsive element to which the thyroid transcription factor TTF-2 binds. The TTF-2 cDNA, encoded by the titf2 locus, has recently been cloned and classified as a member of the forkhead transcription factor family. Here, we demonstrate that TTF-2 mRNA levels become undetectable in FRTL-5 thyroid cells cultured for 4 days in 0.2% serum and in the absent of thyrotropin (TSH) and insulin. Addition of TSH, insulin or insulin-like growth factor I (IGF-I) to the culture medium increases the levels of this transcription factor in a dose-and timedependent manner and requires ongoing protein synthesis. The TSH effect is greater than that produced by insulin or IGF-I and is similar to the effect produced by the cAMP analog forskolin. The TSH and insulin effects are additive. In all cases, the mRNA levels increase is accompanied by an increase in transcription rate, as demonstrated by run-off assays. These data demonstrate that the TTF-2 mRNA is under tight hormonal control. This is consistent with an important role for TTF-2 as a mediator of the transcriptional activation of thyroidspecific genes (thyroglobulin and thyroperoxidase) by TSH via cAMP and by insulin through the IGF-I receptor.

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mentioning

confidence: 99%

Transcriptional Control of the Forkhead Thyroid Transcription Factor TTF-2 by Thyrotropin, Insulin, and Insulin-like Growth Factor I

Ortíz¹,

Zannini²,

Lauro³

et al. 1997

Journal of Biological Chemistry

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“…A significant effect of iodide on the specific radioactivity appeared only in the presence of TSH:+TSH+KI/+TSH-KI=1.4. Different stages of thyroglobulin expression have been studied for their dependence on TSH, and the maximal responses were not obtained with the same concentration of hormone for each process (26). The usual concentration of TSH in that culture system was 100 mU/ml, added to the basolateral side of the cells; at this concentration all the effects of TSH reached a plateau.…”

Section: Regulation Of the Incorporation Of Sulfate Residues Into Thymentioning

confidence: 99%

“…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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“…Total cellular RNA was isolated as previously described (Chabaud et al, 1988). The amount of total cellular RNA was determined in each assay by absorbance at 260 nm (Eo.…”

Section: Rna Isolation and Quantificationmentioning

confidence: 99%

“…Tg mRNA content was determined from dot-hybridization assays (Chabaud et al, 1988). Briefly, a precisely measured amount (10-20-pg range) of cellular RNA from each assay was incubated a t 50°C for 30 min in a 2 0 4 glyoxal-dimethylsulfoxide (DMSO) mixture as described by Tosta et al (1983).…”

Section: Rna Isolation and Quantificationmentioning

confidence: 99%

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

Desruisseau

Alquier

Depétris

et al. 1994

Journal Cellular Physiology

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Porcine thyroid cells were cultured for 15 days on porous bottom chambers with or without different mixtures of hormones added to serum-free basal medium. Assays with 10% serum were also performed for comparison with previously published results. The effects of the hormones, particularly insulin, TSH and hydrocortisone, were studied on total RNA content, thyroglobulin mRNA level, the amount of thyroglobulin secreted into the apical medium and on glycosylation. Insulin and TSH similarly increased the total RNA content, and their effects were additive. Thyroglobulin mRNA content was increased twofold by insulin and threefold by TSH. When they were added simultaneously, the maximal level of thyroglobulin mRNA was reached, showing that TSH and insulin effects on thyroglobulin gene expression were additive. Hydrocortisone alone did not modify total RNA or thyroglobulin mRNA content but the hormone amplified total RNA when insulin and TSH were present together. The basal level of thyroglobulin secreted into the apical medium was increased threefold by insulin and fourfold by TSH. The effects of these two hormones added together appeared to be additive. Hydrocortisone had no effect alone or even when combined with insulin or TSH. However, when the three hormones were added together, the hormonal response was amplified. TSH effect and insulin effect on the incorporation of 3H-mannose into thyroglobulin as well as on the anionic residue content of the molecule were additive.

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Thyrotrophin and cyclic AMP regulation of thyroglobulin gene expression in cultured porcine thyroid cells

Cited by 30 publications

References 25 publications

Transcriptional Control of the Forkhead Thyroid Transcription Factor TTF-2 by Thyrotropin, Insulin, and Insulin-like Growth Factor I

Transcriptional Control of the Forkhead Thyroid Transcription Factor TTF-2 by Thyrotropin, Insulin, and Insulin-like Growth Factor I

Thyrotropin regulates tyrosine sulfation of thyroglobulin

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

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