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Regulation of growth hormone messenger rna synthesis by 3 5 3' triiodo l thyronine in cultured growth hormone producing rat pituitary tumor cells gc cells dissociation between nuclear iodothyronine receptor concentration and growth hormone messenger rna synthesis during the dna synthesis phase of the cell cycle


, : Regulation of growth hormone messenger rna synthesis by 3 5 3' triiodo l thyronine in cultured growth hormone producing rat pituitary tumor cells gc cells dissociation between nuclear iodothyronine receptor concentration and growth hormone messenger rna synthesis during the dna synthesis phase of the cell cycle. Journal of Biological Chemistry 260(27): 14529-14537

3,5,3'-Triiodo-L-thyronine (T3) regulates the growth rate and GH production of cultured GC cells, a rat piutuitary tumour cell line. We have previously demonstrated a parallel increase in cellular content of DNA and nuclear T3 glucocorticoid receptors during the DNA synthesis (S) phase of the GC cell growth cycle. To determine the relationship between the increase in nuclear hormone receptors and GH production in S-phase cultures, we measured the synthesis rate of GH by pulse-labeling with [3H] leucine and immunoprecipitation as well as the relative concentration of GH mRNA by dot hybridization employing formaldehyde-treated cytoplasm and Gh cDNA. Total protein synthesis was similar in S-phase and asynchronous cultures. However, in comparison to asynchronous cultures, S-phase cells had an increased GH synthesis rate, p < 0.005 (from 13,430 .+-. 609 to 19,150 .+-. 1160 cpm/106 cells/2 h) and increased GH in RNA, p < 0.001 (from 7.2 .+-. 1.2 to 14.5 .+-. 1.5 relative A units. The S-phase-associated augmentation in GH production did not appear to result from a decrease in ADP-ribosylation induced by 2 mM thymidine treatment which was utilized for the S-phase synchronization. To determine whether increased GH mRNA and GH synthesis in S-phase was associated with an increase in synthesis of GH mRNA, we measured the incorporation of [3H] uridine into GH mRNA by incubating partially snychronized S-phase cells with [3H] uridine and isolating 3H-labeled GH mRNA by hybridization to GH cDNA immoblized on introcellulose filters. Total RNA synthesis was similar in asynchronous, S-phase and G1 cell populations. However, the mean incorporation of [3H] uridine into GH mRNA of S-phase cultures was decreased to 52,59, and 61% (counts/min of GH mRNA/106 cells), 49, 59 and 65% (ppm of total RNA), and 64 and 69% (ppm of poly (A)+ RNA) of asynchronous cultures. Our studies show further that the decrease in [3H]uridine incorporation into GH mRNA did not result from a cell cycle specific change in efficiency of hybridization or exclusively to an S-phase associated increased rate of degradation of GH mRNa. Thus, despite increased nuclear T3 and glucocorticoid receptors and, increased GH and mRNA and GH synthesis, the synthesis rate of GH mRNa appears decreased in S-phase GC cells. Furthermore, the close relationship between nuclear iodothyronine receptors and GH mRNA synthesis observed by others in asynchronous cells is not apparent in S-phase cells. Our data suggest that position in the cell cycel may mediate the activity of nucleur iodothyronine receptors as expressed by the synthesis of GH mRNA.

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Related references

Kumara Siri, M.H.; Surks, M.I., 1985: Regulation of growth hormone mRNA synthesis by 3,5,3'-triiodo- L-thyronine in cultured growth hormone-producing rat pituitary tumor cells (GC cells). Dissociation between nuclear iodothyronine receptor concentration and growth hormone mRNA synthesis during the deoxyribonucleic acid synthesis phase of the cell cycle. The Journal of Biological Chemistry 260: 529-37

Kumara-Siri, M.H.; Surks, M.I., 1985: Regulation of growth hormone mRNA synthesis by 3,5,3'-triiodo-L-thyronine in cultured growth hormone-producing rat pituitary tumor cells (GC cells). Dissociation between nuclear iodothyronine receptor concentration and growth hormone mRNA synthesis during the deoxyribonucleic acid synthesis phase of the cell cycle. 3,5,3'-Triiodo-L-thyronine (T3) regulates the growth rate and GH production of cultured GC cells, a rat pituitary tumor cell line. We have previously demonstrated a parallel increase in cellular content of DNA and nuclear T3 and glucocorticoi...

Kumara Siri M.H.; Surks M.I., 1985: Dissociation between nuclear triiodothyronine receptor concentration and growth hormone messenger rna synthesis during the dna synthesis s phase of the gc cell growth cycle. Clinical Research 33(2 PART 1): 600A

Samuels, H.H.; Stanley, F.; Shapiro, L.E., 1979: Control of growth hormone synthesis in cultured GH1 cells by 3,5,3'-triiodo-L-thyronine and glucocorticoid agonists and antagonists: studies on the independent and synergistic regulation of the growth hormone response. Thyroid hormone induction of growth hormone synthesis and mRNA in cultured GH1 cells, a rat pituitary cell line, is modulated by the thyroid hormone nuclear receptor. In addition, the induction of growth hormone synthesis and mRNA by glucocorticoi...

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Diamond D.J.; Goodman H.M., 1985: Regulation of growth hormone messenger rna synthesis by dexamethasone and triiodothyronine transcriptional rate and messenger rna stability changes in pituitary tumor cells. The process was characterized by which the growth hormone (GH) gene is stimulated in rat pituitary tumor cells (GC or GH3) by the steroid hormone dexamethasone (Dex) and the thyroid hormone, L-triiodothyronine (T3). A primary transcriptional respo...

Labrie F., 1985: Interactions between growth hormone releasing factor and thyroid and glucocorticoid hormones on growth hormone secretion growth hormone synthesis and growth hormone messenger rna levels in rat adenohypophyseal cells in culture. Canadian Journal Of Physiology & Pharmacology: Axxviii

Samuels, H.H.; Stanley, F.; Shapiro, L.E., 1977: Modulation of thyroid hormone nuclear receptor levels by 3,5,3'-triiodo-L-thyronine in GH1 cells. Evidence for two functional components of nuclear-bound receptor and relationship to the induction of growth hormone synthesis. Journal of Biological Chemistry 252(17): 6052-6060

Samuels, H.H.; Stanley, F.; Casanova, J., 1979: Relationship of receptor affinity to the modulation of thyroid hormone nuclear receptor levels and growth hormone synthesis by L-triiodothyronine and iodothyronine analogues in cultured GH1 cells. We have previously demonstrated that L-triiodothyronine (L-T3) induces an increase in growth hormone synthesis and messenger RNA in cultured GH1 cells, a rat pituitary cell line. In addition to regulating the growth hormone response, L-T3 elicits...

Samuels H.H.; Stanley F.; Shapiro L.E., 1979: Control of growth hormone synthesis in cultured gh 1 cells by 3 5 3 tri iodo l thyronine and gluco corticoid agonists and antagonists studies on the independent and synergistic regulation of the growth hormone response. Thyroid hormone induction of growth hormone synthesis and mRNA in cultured GH1 cells, a rat pituitary cell line, is modulated by the thyroid hormone nuclear receptor. In addition, the induction of growth hormone synthesis and mRNA by glucocorticoi...