Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thyrotropin (TSH) treatment of bovine thyroid slices increased 32P-labeling of chromosomal high mobility group 14 (HMG) protein approximately 2-fold. Analogs of cAMP, but not cGMP, also enhanced phosphorylation of HMG 14. The sites of phosphorylation were analyzed by partial acid hydrolysis and by two-dimensional mapping of tryptic digests of 32P-labeled HMG 14 which was purified from control and TSH-treated thyroid tissue. TSH treatment enhanced phosphorylation at serine residues in four prominent tryptic phosphopeptides which were identical with those derived from HMG 14 phosphorylated in vitro with cAMP- and cGMP-dependent protein kinases. The four tryptic phosphopeptides contain serine 6, the major site of in vitro phosphorylation catalyzed by cyclic nucleotide-dependent protein kinases (Walton, G. M., Spiess, J., and Gill, G. N. (1982) J. Biol. Chem. 257, 4661-4668). TSH did not affect phosphorylation of serine 24, a minor site of phosphorylation in vitro. These studies suggest that TSH-stimulated phosphorylation of HMG 14 is catalyzed by cAMP-dependent protein kinase.
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PMID:Thyrotropin-stimulated phosphorylation of high mobility group protein 14 in vivo at the site catalyzed by cyclic nucleotide-dependent protein kinases in vitro. 632 16

The human glycoprotein alpha-subunit is the common subunit of the heterodimeric hormones CG (hCG), TSH, LH, and FSH. Human glycoprotein alpha-subunit is produced eutopically in placenta, pituitary, and choriocarcinoma and ectopically in a large variety of human tumors. We report ectopic glycoprotein alpha-subunit messenger RNA (mRNA) and peptide production in the human hepatoma cell line, NPLC. Neither hCG beta mRNA nor intact hCG peptide was detected. Antimetabolite regulation of glycoprotein alpha-subunit expression in NPLC cells resembled that found in choriocarcinoma cells in that it was stimulated by hydroxyurea. In addition, glycoprotein alpha-subunit mRNA expression and transcription in NPLC were stimulated by activators of the protein kinase A and C second messenger pathways, as well as by glucocorticoid. Glucocorticoid augmented glycoprotein alpha-subunit gene transcription by phorbol ester and forskolin, in contrast to its simultaneous inhibitory effect on phorbol ester activation of the CRH gene, which is also ectopically expressed in these cells. Glucocorticoid thus modulates the activation of these genes by phorbol ester in opposite directions, despite their identical cellular context. The NPLC cell line provides a new model for the study of human glycoprotein alpha-subunit gene regulation and free glycoprotein alpha-subunit secretion. In addition, it should be useful for investigating the role that specific cis-acting DNA sequences play in glucocorticoid modulation of gene induction by second messenger pathways.
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PMID:Regulation of the ectopically expressed human glycoprotein alpha-subunit gene in the human hepatoma cell line NPLC. 750 28

The present studies were undertaken to investigate the effect of gender on thyrotropin-releasing hormone (TRH) gene expression in cultured anterior pituitary (AP) cells. AP cells derived from 15-day-old male, female, or female pups that had been neonatally treated with testosterone propionate (TP), were cultured for up to 18 days in a modified DMEM/L-15 medium containing 10% fetal calf serum. TRH and AP hormones including GH, prolactin (PRL), luteinizing hormone (LH) and thyrotropin (TSH) were measured by RIA, proTRH mRNA was determined by in situ hybridization using a full-length riboprobe followed by quantification with a computer-assisted image analysis system. Cultures derived from female rats contained significantly (p < 0.01) higher amounts of TRH and secreted approximately twice (p < 0.01) as much TRH under basal conditions and in response to activators of the protein kinase A and C pathways, respectively. In situ hybridization studies revealed that 'female' cultures contained significantly higher amounts of proTRH mRNA compared to 'male' cultures. Computer-assisted image analysis demonstrated that proTRH mRNA levels were 3.5 times higher in 'female' compared to 'male' cultures (p < 0.01), an effect that was the result of a significantly higher number (3 times; p < 0.01) of cells expressing proTRH mRNA in 'female' cultures. Neonatal TP treatment did not affect either proTRH mRNA or TRH peptide levels. In vitro testosterone treatment resulted in a moderate rise (p < 0.05) of intracellular TRH accumulation in cultures from both sexes, however, proTRH mRNA levels remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Thyrotropin-releasing hormone gene expression in cultured anterior pituitary cells: role of gender. 773

Growth of thyroid cancer cells is stimulated by various growth factors via signal transduction pathways. TSH, EGF, IGF, and TGF-alpha stimulate and TGF-beta inhibits thyroid cell growth. TSH stimulates thyroid cells via both the adenylate cyclase-PKA and the PLC-PKC-Ca signal transduction pathways. TSH-r, ras, gsp, ret, trk, and myc are oncogenes that are activated in some thyroid neoplasms. P53 and RB are tumor suppressor genes that are inactivated in some thyroid cancers.
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PMID:Thyroid growth factors, signal transduction pathways, and oncogenes. 774 50

To study the growth control of human thyroid cells in different stages of differentiation, we established two human thyroid cell lines of adenomatous goiter and papillary carcinoma. A 59-year-old female patient with adenomatous goiter was operated in September 1991, and a 27-year-old female patient with papillary carcinoma in May 1990. The thyroid cell lines were established by successive passage without cellular or genetic manipulations such as fusing other cell lines or oncogenic viral infection. These cell lines, human adenomatous goiter cells (hAG) and human papillary thyroid carcinoma cells (hPTC), exhibited a flattened polygonal shape and proliferated as a monolayer in cell culture. The doubling time of the hAG cells was 60 h in Ham's F12 medium supplemented with 10% fetal bovine serum, and that of the hPTC cells, 18 h in the same medium. Both cell lines expressed mRNA for TSH receptor and secreted cAMP into the medium during incubation with thyrotropin (TSH) at concentrations as low as 0.01 mU/mL. The effects of activators of protein kinase A (PKA), protein kinase C (PKC), tyrosine kinase (TK), and estradiol (E2) on proliferation of the hAG cells and the hPTC cells were assessed by measuring cellular DNA content in 24-well plates with diaminobenzoic acid. TSH stimulated proliferation of the hAG cells, but it inhibited proliferation of the hPTC cells. Since TSH activates two signaling pathways, the adenyl cyclase-PKA system and phospholipase C-PKC system, we tested effects of dibutylyl cAMP (dBC) and phorbol myristate 13-acetate (PMA), separately. dBC stimulated proliferation of the hAG cells, but it inhibited that of the hPTC cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Different growth control of the two human thyroid cell lines of adenomatous goiter and papillary carcinoma. 778 32

The production of hydrogen peroxide (H2O2) as an essential process for iodide organification is a key reaction in TSH-induced thyroid hormone synthesis. Here we characterize the signal transduction pathway involved in TSH-induced H2O2 production in FRTL-5 thyroid cells. At higher than 1 nM TSH, N6-(L-2-phenylisopropyl)adenosine (PIA), an adenosine receptor agonist having, by itself, no influence on H2O2 generation, potentiated this TSH action, whereas the TSH increase and PIA addition reduced cAMP accumulation. RO 20-1724, a phosphodiesterase inhibitor, amplified the TSH-induced cAMP accumulation, but did not change H2O2 generation in the whole range of TSH used. Ca(2+)-mobilizing agonists, GTP and ATP, also induced H2O2 production without stimulating cAMP accumulation. Chelation of intracellular Ca2+ markedly inhibited the TSH action, but intracellular Ca2+ increases by either thapsigargin or ionomycin mimicking it. All of the findings show the participation of Ca2+, but not cAMP, in the action of TSH. Desensitization of protein kinase-C (PKC) did not influence the receptor-mediated H2O2 production, suggesting the reduced importance of PKC activation compared to Ca2+ signaling to the reaction. A rise in intracellular Ca2+ independent of receptor activation also induced H2O2 production as well as arachidonate release, and both were potentiated by PIA. In addition, inhibitors of phospholipase-A2 and the arachidonate metabolic pathway depressed H2O2 generation, suggesting the participation of an arachidonate cascade in the Ca(2+)-dependent H2O2 production. Lipoxygenase inhibitors depressed the Ca2+ action without influencing arachidonate release, suggesting the involvement of a lipoxygenase product(s) of arachidonate in the Ca(2+)-signaling mechanism. In conclusion, in FRTL-5 cells, TSH-induced H2O2 production is mediated not by cAMP, but by the phospholipase-C/Ca2+ cascade, possibly followed by the Ca(2+)-dependent phospholipase-A2/arachidonate cascade. PIA amplifies TSH-induced H2O2 production at the steps of phospholipase-C and phospholipase-A2 activation in a pertussis toxin-sensitive manner.
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PMID:Thyrotropin-induced hydrogen peroxide production in FRTL-5 thyroid cells is mediated not by adenosine 3',5'-monophosphate, but by Ca2+ signaling followed by phospholipase-A2 activation and potentiated by an adenosine derivative. 782 20

The present study investigated the importance of pulsatile vs. continuous protein kinase-C (PKC) stimulation in regulating pituitary gene expression. Adult female rat pituitaries were dissociated, and cells were plated for 48 h, then inserted into perifusion chambers (n = 5-8/group). Chambers received pulses of GnRH (100 pM) plus TRH (4 nM) or sn-1,2-dioctanoylglycerol (DOG; peak chamber concentration, 0.2, 1, or 5 mM; vehicle pulses to controls) every 60 min or a continuous infusion of phorbol 12-myristate 13-acetate (PMA; 20 nM). Secretory responses were determined in perifusate fractions collected after 2 and 22 h of perifusion. After 24 h of treatment, the cells were recovered, total RNA was extracted, and messenger RNAs (mRNAs) were measured by dot blot hybridization. The data revealed that GnRH plus TRH and both pulsatile (DOG) and continuous (PMA) PKC stimulation increased LH, FSH, TSH, and PRL secretory activity. Pulses of GnRH plus TRH increased PRL, alpha, TSH beta, and FSH beta mRNAs, but not LH beta mRNA. Pulsatile DOG only increased LH beta and PRL mRNAs, with maximal responses seen after the 1-mM dose for LH beta and the 0.2-mM dose for PRL. In contrast, PMA stimulated significant increases in alpha, LH beta, and TSH beta, but not PRL or FSH beta. These data show that alpha, TSH beta, LH beta, and PRL mRNA expression are regulated by PKC. Maximal increases are seen after continuous stimulation (via PMA), with the exception of PRL, which requires a pulsatile signal pattern. Thus, intermittent activation of PKC does not appear to play a major role in regulating pituitary gene expression.
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PMID:Regulation of gonadotropin, thyrotropin subunit, and prolactin messenger ribonucleic acid expression by pulsatile or continuous protein kinase-C stimulation. 782 22

Cellular growth control requires the coordination and integration of multiple signaling pathways which are likely to be activated concomitantly. Mitogenic signaling initiated by thyrotropin (TSH) in thyroid cells seems to require two distinct signaling pathways, a cyclic AMP (cAMP)-dependent signaling pathway and a Ras-dependent pathway. This is a paradox, since activated cAMP-dependent protein kinase disrupts Ras-dependent signaling induced by growth factors such as epidermal growth factor and platelet-derived growth factor. This inhibition may occur by preventing Raf-1 protein kinase from binding to Ras, an event thought to be necessary for the activation of Raf-1 and the subsequent activation of the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinases (MEKs) and MAP kinase (MAPK)/ERKs. Here we report that serum-stimulated hyperphosphorylation of Raf-1 was inhibited by TSH treatment of Wistar rat thyroid cells, indicating that in this cell line, as in other cell types, increases in intracellular cAMP levels inhibit activation of downstream kinases targeted by Ras. Ras-stimulated expression of genes containing AP-1 promoter elements was similarly inhibited by TSH. On the other hand, stimulation of thyroid cells with TSH resulted in stimulation of DNA synthesis which was Ras dependent but both Raf-1 and MEK independent. We also show that Ras-stimulated DNA synthesis required the use of this kinase cascade in untreated quiescent cells but not in TSH-treated cells. These data suggest that in TSH-treated thyroid cells, Ras might be able to signal through effectors other than the well-studied cytoplasmic kinase cascade.
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PMID:Thyrotropin-induced mitogenesis is Ras dependent but appears to bypass the Raf-dependent cytoplasmic kinase cascade. 786 10

The dog thyrocyte I- trapping activity and the expression of the genes coding for dog thyrocyte thyroglobulin or thyroid peroxidase are enhanced by TSH through the cAMP cascade and reduced by mitogens such as epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol 13-acetate (TPA). In this work, we investigated whether H2O2 generation (a limiting step of thyroid hormone synthesis) is modulated by chronic treatment of the thyrocyte with TSH or mitogens such as EGF or TPA. We observed that both basal and carbachol- or ionomycin-stimulated H2O2 generation by the dog thyrocyte were concentration and time dependently enhanced by prolonged (12- to 72-h) exposure to TSH. This effect was reproduced by agents that increase the dog thyrocyte cAMP level or that mimic this increase. It was abolished when protein or RNA synthesis was inhibited. By contrast, EGF and TPA concentration and time dependently antagonized the effect of TSH. In addition, chronic exposure to EGF reduced both basal and carbachol- or ionomycin-stimulated H2O2 generation. The effect of TPA was reproduced by another protein kinase-C activating phorbol ester, phorbol dibutyrate, but not by beta-phorbol, an inactive phorbol ester. Modulation of dog thyrocyte H2O2 generation by chronic exposure to TSH or to the mitogens EGF and TPA was totally parallel to the modulation of their 125I- uptake. Taken together our results suggest that H2O2 generation (or at least one of its constituents) is a differentiation characteristic of the dog thyrocyte under tonic control of TSH through the cAMP cascade as iodide transport, thyroid peroxidase, and thyroglobulin.
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PMID:Tonic modulation of dog thyrocyte H2O2 generation and I- uptake by thyrotropin through the cyclic adenosine 3',5'-monophosphate cascade. 786 6

The aim of the present study was to characterize the adrenergic receptors mediating the effects of norepinephrine on PC C13 rat thyroid cells and identify the molecular mechanisms by which TSH regulates the noradrenergic response. We studied TSH regulation of norepinephrine-induced cytosolic calcium increase by means of the fluorescent probe fura-2. In PC C13 cells grown and maintained in a medium containing TSH (PC C13 6H), norepinephrine caused a higher increase in cytosolic calcium than in PC C13 starved from TSH 5 days before the experiments (PC C13 5H). In both group of cells the calcium response to norepinephrine was concentration dependent and reduced by the removal of extracellular calcium ions. Reintroduction of TSH in the culture medium of the PC C13 5H cells induced the recovery of the norepinephrine-stimulated intracellular calcium rise similarly to that in the native PC C13 6H. This effect was complete after a 48-h incubation period and was abolished by the simultaneous treatment of the cells with the protein synthesis inhibitor cycloheximide, suggesting that TSH may stimulate the synthesis of alpha 1-adrenergic receptors in PC C13 cells. Because in these cells we found that TSH increased cAMP levels as well as inositol phosphate production, we tested whether the activation of a protein kinase-A and/or protein kinase-C was involved in TSH regulation of the adrenergic response. We found that the treatment of PC C13 5H cells with forskolin restored the effect of norepinephrine on the calcium level, and that KT5720, an inhibitor of the protein kinase-A, was able to prevent the recovery of the noradrenergic response induced by the readdition of TSH to the culture medium of PC C13 5H. Conversely, treatment of PC C13 5H cells with the protein kinase-C activator phorbol 12-myristate 13-acetate was ineffective. Norepinephrine also stimulated inositol phosphate production in PC C13 6H and, to a lesser extent, in PC C13 5H, but it did not affect the cAMP levels in the two groups of cells. To characterize alpha 1-adrenergic receptor subtypes mediating the effects of norepinephrine in PC C13 cells, we used antagonists of alpha 1A and alpha 1B receptors (WB4101 and chlorethylclonidine respectively).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Alpha 1A- and alpha 1B-adrenergic receptors mediate the effect of norepinephrine on cytosolic calcium levels in rat PC C13 thyroid cells: thyrotropin modulation of alpha 1B-linked response via a adenosine 3',5'-monophosphate-protein kinase-A-dependent pathway. 790 35


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