Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

We have characterized the mouse Mos proto-oncogene product, pp39Mos, in murine fibroblasts. When expressed in NIH3T3 cells under the influence of the long terminal repeat regulatory element from Moloney murine sarcoma virus [NIH(pTS-1) cells], the Mos protein was present in low levels and had a half-life of about 30 min. In extracts from NIH(pTS-1) cells, we detected additional forms of Mos protein that apparently arose from internal initiation codons (p24Mos and p29Mos) or from upstream non-AUG initiation codons (p42Mos and p44Mos). The Mos protein was found to exist in these cells as a phosphoprotein, pp39Mos, and, when immunoprecipitated with an antiserum specific for the Mos N-terminus [anti-Mos(6-24)], had autophosphorylating kinase activity. We found that anti-Mos(6-24) also detected non-Mos protein kinase activity and non-Mos phosphoproteins in addition to p39Mos. We present evidence, on both the RNA and protein levels, that non-transformed mouse 3T3 cells do not express endogenous Mos.
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PMID:Characterization of activated and normal mouse Mos gene in murine 3T3 cells. 146 52

In this report we review the current knowledge on the involvement of the interferon (IFN) system in the regulation of cell growth and differentiation. We also summarize our own data which provide evidence for the strong correlation between IFN-mediated growth-arrest of transformed cells and the elevated enzymatic activity of an IFN-induced protein. Similarly, it is demonstrated that elevated levels of IFN-induced proteins accompany the early phases of in-vitro cell differentiation. IFN-treatment of NIH/3T3 mouse fibroblasts transformed by Moloney-murine sarcoma virus (MSV) resulted in a significant reduction in the rates of cell growth, protein synthesis and cloning efficiency. In parallel, 2-5A-synthetase activity was induced ten-fold above the background level. Treatment of these cells for 3 days with 450 international units (IU)/ml of IFN followed by its removal, resulted in a gradual increase in all parameters associated with cell growth while the 2-5A-synthetase activity was reduced to its normal level. However, almost no recovery occurred when cells were treated with 1,800 IU/ml. In parallel, 2-5A-synthetase activity remained highly elevated even at 3 days after the removal of IFN. In these cells, the expression of both c-myc and v-mos was reduced rapidly following IFN treatment. Upon removal of IFN after 24 h of treatment, the expression of both genes was resumed but with a different kinetics, suggesting that different mechanisms are responsible for the reduction in gene expression. In rat skeletal muscle cultures which differentiate to form myotubes, the level of both 2-5A-synthetase and protein kinase activities was transiently elevated, reaching a peak at 3 days followed by a decrease to background levels. This peak activity precedes the appearance of the major muscle differentiating proteins.
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PMID:Involvement of interferon-system in the regulation of cell growth and differentiation. 169 10

c-jun is a protooncogene associated with neoplastic transformation and is transcriptionally induced by ionizing radiation. To examine the possible mechanisms of radiation-induced c-jun transcription, we analyzed RNA from human tumor cell lines RIT-3 and STSAR-5 following x-irradiation in the presence of protein kinase inhibitors, or the absence of serum and calcium. Protooncogene c-jun expression increased several fold following irradiation of these radiation-induced human sarcoma cell lines. The expression of c-jun was not altered following irradiation in conditioned medium containing serum as compared to that of cells in serum free medium. Depletion of PKC by prolonged TPA treatment resulted in inhibition of c-jun expression. In addition, nonspecific protein kinase inhibitors, staurosporin and H7 attenuated c-jun expression, whereas the analogue of ATP (sangivamycin) did not. Furthermore, the selective inhibitor of cAMP dependent protein kinase HA 1004 did not alter radiation-mediated c-jun induction. These data indicate that ionizing radiation exposure results in c-jun induction which is dependent upon the activation of PKC. Protein kinase C activation and the subsequent expression of the protooncogene c-jun by ionizing radiation may further define the molecular mechanisms of radiation-induced neoplastic transformation.
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PMID:Mechanisms of X-ray-mediated protooncogene c-jun expression in radiation-induced human sarcoma cell lines. 180 83

Exposure of rat thyroid cells for 1 week to a temperature-sensitive variant of Kirsten murine sarcoma virus (KiMSV) Ras inactivated the thyroglobulin promoter (pTg). Cellular dedifferentiation was paralleled by the loss of the thyroid-specific trans-acting factor, TgTF1, which binds to pTg. When Ras was denatured by shifting cells to 39 degrees C, TgTF1 binding and pTg function recovered rapidly without the synthesis of new protein. TgTF1 could be reactivated in vitro by treating nuclear extracts with protein kinase A. After 4 weeks of exposure to the oncogene, denaturation of Ras no longer restored TgTF1 binding or reactivated pTg. Incubation of nuclear extracts with protein kinase A likewise did not reactivate TgTF1. Cells chronically exposed to Ras did, however, yield differentiated clones after treatment with 5-azacytidine. We suggest that Ras induces dedifferentiation in two sequential steps: (1) Ras reduces PKA activity; TgTF1 (or an auxiliary protein) becomes dephosphorylated, and binding to pTg is abolished. (2) The effects of Ras become imprinted by methylation, possibly of the TgTF1 gene.
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PMID:Reversible inhibition of a thyroid-specific trans-acting factor by Ras. 198 5

We investigated cell cycle-dependent regulation of protein kinase activity encoded by the viral mos gene by using a normal rat kidney cell line (NRK-6m2) chronically infected with a temperature-sensitive mutant (ts110) of Moloney murine sarcoma virus, which produces the P85gag-mos transforming protein. In elutriation experiments, in which cells in various phases of the cell cycle are separated based upon size, a twofold increase in the specific activity of the P85gag-mos protein kinase was observed as cells progressed from G0/G1 through S and G2/M. A three- to fourfold increase in gas-mos protein kinase specific activity relative to unsynchronized cells was observed in mitotic NRK-6m2 cells synchronized by treatment with thymidine followed by colcemid or with nocodazole alone. Interestingly, the gag-mos protein was structurally altered in mitotic cells generating a protein species moving slower than P85gag-mos in SDS-polyacrylamide gels. Our findings indicate that viral mos protein kinase activity is regulated during the cell cycle via phosphorylation. We propose that the mos transforming protein functions in a pleiotropic manner, affecting both cytoplasmic and nuclear targets.
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PMID:Cell cycle-mediated structural and functional alteration of P85gag-mos protein kinase activity. 213 25

Moloney murine sarcoma virus ts110 possesses a thermosensitive splicing defect. By continuously growing nonproducer cells at the nonpermissive temperature, a new class of revertant cells, termed 6m3, that had lost the thermosensitive splicing defect was produced, and six distinct clones were selected. These cell clones were transformed at either permissive or restrictive temperatures. Unlike parental 6m2 cells, which contain two virus-specific RNA species of 4.0 and 3.5 kilobases (kb) at temperatures permissive for transformation, the 3.5-kb RNA was the only virus-specific RNA species detected in 6m3 clones. No new v-mos-containing DNA fragment was observed in Southern blot analysis of these cell clones compared with parental 6m2 cells, indicating that the 3.5-kb RNA was a splicing product rather than a direct transcript. Moreover, these cells expressed P85gag-mos but not P58gag at any temperature. The reversion of the phenotype in 6m3 cell clones appears to be the result of a selective loss of the temperature sensitivity of the splicing reaction, without affecting the thermosensitivity of the protein kinase activity. This change also appears to alter the mechanism regulating the efficiency of the genomic RNA-splicing reaction.
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PMID:Reversion of thermosensitive splicing defect of Moloney murine sarcoma virus ts110 by oversplicing of viral RNA. 215 17

The v-mos protein, termed p37v-mos, has a closely associated serine/threonine protein kinase activity. To provide further information about its protein kinase activity, we tested the activity of p37v-mos produced in a cell-free translation system from transcripts generated from a cloned v-mos gene. Anti-mos(37-55) immunoprecipitates of in vitro-produced p37v-mos were found to possess serine/threonine protein kinase activity, whereas those obtained with anti-mos(260-271), known to block v-mos autophosphorylation, lacked kinase activity. The phosphorylated products were identical in size to p37v-mos and p43v-mos produced in protein kinase assays from Moloney murine sarcoma virus-infected cells expressing authentic p37v-mos. These results provide further proof that the protein kinase activity associated with p37v-mos is an intrinsic property of the v-mos gene product. This translation system also provides a useful experimental model to study the activation of the mos protein kinase. Thus, protein kinase assays performed on [35S]methionine-labeled p37v-mos produced p43v-mos at the expense of p37v-mos. Phosphatase treatment removed the p43v-mos species, resulting in increase of the p37v-mos-sized protein, confirming our previous interpretation that p43v-mos is a hyperphosphorylated form of p37v-mos.
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PMID:v-mos protein produced by in vitro translation has protein kinase activity. 215 64

A subpopulation of cells was derived from the Hs431 connective tissue sarcoma cell line which possessed high affinity (estimated Kd = 0.38-0.55 nM) binding sites for human recombinant [125I]-IL-1 alpha. Binding at 4 degrees C was slow approaching equilibrium by 4 hrs. Dissociation of [125I]-IL-1 alpha was also slow and unaffected by high concentrations of cold ligand. The binding site also underwent ligand-induced internalization at 37 degrees C. An Mr = 83,000 protein was identified in affinity crosslinking studies. Despite these similarities to previously reported IL-1 receptors, Hs431 cells did not exhibit biological responses to IL-1 which have been observed in other cell lines. IL-1 did not induce PGE2 or collagenase synthesis. IL-1 also failed to induce ornithine decarboxylase activity (ODC) or stimulate [3H]-thymidine incorporation. In contrast, the Hs431 cells did contain a functional epidermal growth factor (EGF) receptor as determined from binding studies, protein kinase activity, induction of ODC, and stimulation of [3H]-thymidine incorporation. Thus, the refractoriness of Hs431 cells to IL-1 was fairly specific and did not result from a generalized defect associated with cell transformation.
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PMID:Characterization of a high affinity interleukin-1 (IL-1) specific binding site in a human synovial sarcoma (Hs431) cell line. 216 29

Protein kinases are known to undergo phosphorylation to regulate their activity. To determine whether the protein kinase activity of p37v-mos was similarly regulated, we investigated the influence of two well known protein kinases, namely protein kinase C and protein kinase A, on the activity of p37v-mos in vivo. NIH3T3 cells chronically transformed with Moloney murine sarcoma virus 124 were treated with high concentrations (200-400 nM) of phorbol 12-myristate 13-acetate (PMA) for 24-48 h, concentrations known to result in the total loss of protein kinase C by causing its translocation from the cytosol to cell membranes where it is downregulated. PMA treatment caused a drastic decrease in the protein kinase activity of p37v-mos without affecting its steady state level. Similar results were obtained with p85gag-mos expressed in ts110 Mo-MuSV transformed NRK cells. Control treatment with an inactive analogue of PMA, 4-alpha phorbol 12,13-didecanoate, had no effect on the p37v-mos protein kinase activity. Treatment of cells with a direct chemical inhibitor of protein kinase C, H-7 (1-(5-isoquinoline sulfonyl)-2-methylpiperazine dihydrochloride), approximately halved p37v-mos kinase activity, although the drug did not inhibit p37v-mos kinase activity directly in vitro. In contrast to the PMA effect, in vivo activation of protein kinase A by 8-(4-chlorophenylthio)-adenosine 3',5' cyclic monophosphate did not affect p37v-mos protein kinase activity levels. These findings indicate that the protein kinase C pathway but not the protein kinase A pathway modulates v-mos protein kinase activity.
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PMID:Evidence for involvement of the protein kinase C pathway in the activation of p37v-mos protein kinase. 216 30

The role of oncogenes in the acquisition of invasive and metastatic capabilities is controversial. Interactions with basement membranes are critical in the process of tumor invasion and metastasis. We compared the ability of 3T3 cells transformed by oncogenes involved in various stages of signal transduction to invade a reconstituted basement membrane in vitro and to grow in a three dimensional basement membrane gel (matrigel). Cell lines transformed by various oncogenes and oncoviruses: v-sis (a growth factor), v-erb-B (a truncated EGF receptor), Moloney sarcoma virus (v-mos: a protein kinase homologue), mutated c-ras oncogenes (G protein homologues), FBJ virus (v-fos: a nuclear protein) were investigated. All transformed cell lines were able to invade in the chemoinvasion assay, where a layer of matrigel is coated onto chemotaxis filters. FBJ/3T3 were the least invasive and SSV/3T3 the most invasive. Control 3T3 cells could not cross the matrigel barrier. All transformed cells grew on matrigel forming invasive, branching colonies, whereas control 3T3 were unable to grow in matrigel. Cells transfected with the v-erb-B gene grew as multilayers inside matrigel. Invasiveness and growth on matrigel were accompanied by a high chemotactic response to laminin (LN) in all transformed lines. These results suggest that invasion and growth on matrigel, together with migration to LN, are induced by a large spectrum of oncogenes. When 3T3 cells were transfected with v-sis oncogene under the transcriptional control of the metallothionein (MMT) promoter and exposed to Zn++, their in vitro invasiveness was specifically increased by around 3 fold. These findings provide further evidence supporting a direct role of the v-sis oncogene in the invasive phenotype.
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PMID:Invasiveness and chemotactic activity of oncogene transformed NIH/3T3 cells. 233 41


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