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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study we describe the activation of a protein kinase which phosphorylates a peptide, T669, comprising amino acids 663-681 of the epidermal growth factor receptor and containing the phosphate acceptor site Pro-Leu-Thr669-Pro. In the human epidermoid carcinoma cell line KB, T669 kinase activity in cytosolic extracts peaked (up to 15-fold compared with basal levels) 15-30 min after addition of interleukin-1 (IL-1) and closely paralleled receptor occupancy with a half-maximally effective concentration of approximately 100 pM IL-1 alpha. IL-1 treatment elevated T669 kinase activity to a variable extent in selected fibroblast lines, the hepatoma cell line HepG2, and the murine thymoma EL4 6.1. An IL-1 receptor-negative EL4 variant and the B cell lines 70Z/3, CB23, and RPMI 1788 did not respond in this way. All of the cell lines except 70Z/3 showed increased levels of T669 kinase when treated with the protein kinase C activator phorbol myristate acetate and/or with epidermal growth factor. This finding is in agreement with a previous study (Countaway, J. L., Northwood, I. C., and Davis, R. J. (1989) J. Biol. Chem. 264, 10828-10835). Activators of protein kinase A did not mimic the ability of IL-1 to stimulate T669 kinase activity, nor did the protein kinase C inhibitor staurosporine abrogate the effect of IL-1. T669 kinase activity from IL-1-stimulated KB cells was partially purified by ion exchange, hydrophobic interaction, and size exclusion chromatography. The partially purified enzyme phosphorylated myelin basic protein, a characteristic substrate of microtubule-associated protein-2 kinase (MAP-2 kinase) and the peptide Arg-Arg-Arg-(Tyr-Ser-Pro-Thr-Ser-Pro-Ser)4 from RNA polymerase II. Western blotting of chromatographic fractions revealed that T669 kinase activity corresponded with two proteins of 43 and 45 kilodaltons which cross-reacted with antibodies raised against peptide sequences of rat extracellular signal-regulated kinase-1/microtubule-associated protein-2 kinase. T669 kinase activity was critically dependent on the presence of phosphatase inhibitors. Since both the 43- and 45-kDa proteins, immunoprecipitated from [32P]phosphate-labeled cells, demonstrated a dramatic increase in their levels of serine, threonine, and tyrosine phosphorylation after brief treatment with IL-1, we conclude that IL-1 modulates the activity of these extracellular signal-regulated kinase/microtubule-associated protein-2 kinases by altering the level of their phosphorylation.
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PMID:Interleukin-1 represents a new modality for the activation of extracellular signal-regulated kinases/microtubule-associated protein-2 kinases. 165 5

The acute monocytic leukemia cell line THP-1 secretes predominantly IL-1 beta after treatment with bacterial lipopolysaccharide and tumour promoting phorbol ester (PMA). IL-1 alpha is also secreted, but represents less than 10% of the total IL-1 activity. This differential is reflected at the level of mRNA as IL-1 beta mRNA is more abundant than IL-1 alpha mRNA. Studies of transcription in isolated nuclei however indicate that each gene is transcribed at a similar rate, suggesting that post-transcriptional mechanisms regulate the relative abundance of IL-1 alpha and IL-1 beta mRNA. Measurement of RNA half life after addition of alpha-amanitin (an inhibitor of RNA polymerase II) indicate that IL-1 alpha mRNA is not as stable as IL-1 beta mRNA suggesting one mechanism for the different relative levels of RNA.
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PMID:Post-transcriptional control of IL-1 gene expression in the acute monocytic leukemia line THP-1. 326 53

To extent our knowledge on the cytokines possibly involved in the pathophysiology of B-cell chronic lymphocytic leukemia (B-CLL), the mRNA expression of a panel of 10 cytokines was investigated on purified B-CLL cells using a reverse-transcriptase polymerase chain reaction method. Whereas negative RT-PCR signals were recorded for interleukin-1 alpha (IL-1 alpha), IL-2, IL-3, IL-4, IL-5, IL-7, tumor necrosis factor beta (TNF beta), and granulocyte-macrophage colony-stimulating factor, we detected the expression of IL-1 beta, IL-6 and TNF alpha. Furthermore, the constitutive expression of IL-8 mRNA was observed in all 17 B-CLL samples analyzed. mRNA expression was associated with the capacity of the leukemic cells to release IL-8 both constitutively (4.6 +/- 8.1 SD ng/mL) and, to a further extent, after stimulation (14.5 +/- 19.4 ng/mL). The circulating levels of IL-8 were also evaluated in 12 untreated B-CLL sera samples and the overall mean level was significantly higher (P < .01) than in normal sera. In addition, supernatants of purified B-CLL cells cultured in the presence of 12-O-tetradecanoylphorbol-13-acetate showed chemotactic activity towards neutrophils; this activity was neutralized in the presence of an anti-IL-8 antiserum. The mRNA for IL-8 was absent in five B-cell preparations from hairy cell leukemia cases and in four B-cell lines. Normal tonsil CD5+ B cells showed a low expression of IL-8 mRNA only in two of the nine preparations tested and the overall quantity of IL-8 released by these cells after 3 days' incubation was significantly lower compared with that released by B-CLL cells (0.4 +/- 0.3 and 1.6 +/- 0.9 ng/mL under basal and stimulated conditions, respectively). These findings point to an involvement of a member of the proinflammatory chemokine supergene family in human CD5+ B lymphocytes. The different IL-8 behavior observed between B-CLL cells and their normal counterpart is likely to reflect an activation state of the leukemic population.
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PMID:Cytokine gene expression in B-cell chronic lymphocytic leukemia: evidence of constitutive interleukin-8 (IL-8) mRNA expression and secretion of biologically active IL-8 protein. 751 9

Substance P (SP) is a neuropeptide widely distributed in the nervous system. Its release within the bone marrow (BM) can mediate bidirectional neurohematopoietic communication via specific receptors: neurokinin-1R (NK-1R), NK-2R, or NK-3R. We have previously reported that SP effects on hematopoiesis are mediated by an NK-1-type receptor, the BM stroma, and growth factors. Here, we have studied the induction of stem cell factor (SCF) and interleukin-1 (IL-1) by SP in stroma. At 10(-9) mol/L SP, cytokine levels in supernatants were IL-1 alpha, 20 +/- 5 ng/mL; IL-1 beta, 40 +/- 10 ng/mL; and SCF, nondetectable; and the cell-associated levels were SCF, 21 +/- 2 ng/mL; IL-1 alpha, 90 +/- 6 ng/mL; and IL-1 beta, 45 +/- 3 ng/mL. Reverse transcriptase-polymerase chain reaction and ligand-binding studies with stroma stimulated by these two cytokines resulted in (1) NK-1-like receptor mRNA accumulation and (2) downregulation of SP binding sites (day 1) followed by an upregulation (day 3). Low numbers of high-affinity receptors were expressed by day 1 but not by day 3. The results indicate that SP induces IL-1 and SCF in stroma and that these cytokines have the potential to autoregulate NK-R.
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PMID:Substance P (SP) mediates production of stem cell factor and interleukin-1 in bone marrow stroma: potential autoregulatory role for these cytokines in SP receptor expression and induction. 754 64

Reverse transcriptase-polymerase chain reaction amplification (RT-PCR) and Southern blot analysis were used to evaluate ligand and receptor expression of interleukin 1 alpha (IL-1 alpha), interleukin 3 (IL-3), interleukin 6 (IL-6) and stem cell factor (SCF) in peripheral blood lymphocytes and monocytes and in several acute leukemia blast cell populations. Resting peripheral lymphocytes and monocytes expressed both ligand and receptor of the four cytokines at considerable levels. The leukemic blast cells of the M1-M4 phenotypes are characterized by almost complete lack of expression of IL-1 alpha, IL-3 and IL-6 and the constant and usually high expression of SCF. On the other hand, these myeloid blast cells express generally high levels of the four cytokine receptors. The data suggest that the regulation of the expression of IL-1 alpha, IL-3 and IL-6, at least in our limited number of leukemic cell populations studied, is independent of that of SCF. The results indicate that, at least in most of the leukemic myeloid blasts cells, the expression of SCF and its receptor, the c-kit oncogene, may permit an autocrine regulation of cell cycling.
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PMID:Expression of interleukins 1, 3, 6, stem cell factor and their receptors in acute leukemia blast cells and in normal peripheral lymphocytes and monocytes. 768 16

A novel immunomodulator, imiquimod, has been shown to be an effective topical antiviral and antitumor agent in animal models. Imiquimod has been reported to induce interferon-alpha and other cytokines in animals and humans, but its precise role as an immunomodulator at skin sites has not been determined. We investigated its effect on cytokine gene expression in the human epidermal carcinoma cell line COLO-16 and human keratinocytes. COLO-16 cells were incubated with imiquimod (1 and 10 micrograms/ml) and human keratinocytes with 5 micrograms/ml for 6 or 24 h. Cytokine gene expression was analyzed by reverse-transcriptase PCR. In COLO-16 cells, imiquimod stimulated IL-6 mRNA levels 2.3- and 4.4-fold at 1 and 10 micrograms/ml after 6 h. IL-8 mRNA increased 4-fold at both 1 and 10 micrograms/ml. At 24 h, though IL-6 mRNA level at 1 micrograms/ml was further stimulated, enhanced expressions of IL-8 at 1 micrograms/ml and both IL-6 and IL-8 at 10 micrograms/ml were down-regulated. In human keratinocytes, 5 micrograms/ml of imiquimod stimulated IL-6 mRNA levels 1.4-fold at 6 h and 2.1-fold at 24 h, and IL-8 mRNA levels 1.7- and 2.0-fold at 6 and 24 h. IL-1 alpha mRNA levels in COLO-16 or keratinocytes were unchanged by either dose or incubation time. These results suggest that stimulation of IL-6 and IL-8 expression may be involved in the immunomodulating action of imiquimod.
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PMID:Effects of a novel topical immunomodulator, imiquimod, on keratinocyte cytokine gene expression. 806 Nov 17

The IL-1R antagonist protein (IRAP) is a competitive inhibitor of IL-1, which is predominantly synthesized by monocytes. We show that this molecule is also expressed in human synovial fibroblasts and dermal fibroblasts (CRL 1445). IRAP mRNA was regulated in a time- and dose-dependent manner by IL-1 alpha, TNF-alpha, LPS, and PMA. Maximal induction of IRAP mRNA was observed between 8 and 16 h after stimulation with IL-1 alpha (1 U/ml), TNF-alpha (10 U/ml), LPS (50 ng/ml), and PMA (10 ng/ml). Their relative efficacy was as follows: PMA > LPS > IL-1 alpha > TNF-alpha. Potentiation was observed when fibroblasts were treated with IL-1 alpha plus basic fibroblast growth factor and IL-1 alpha plus platelet-derived growth factor-BB homodimer. Although LPS and PMA were the best inducers of IRAP mRNA, quantitation of the IRAP protein revealed that its synthesis and release were differentially regulated. Immunoprecipitation and SDS-PAGE of culture supernatant from LPS-treated cells and cell lysates of fibroblasts treated with LPS or PMA showed a single IRAP band with a molecular mass of approximately 22 kDa. Very little IRAP was detected in culture supernatants of cells treated with PMA. Quantitation of IRAP revealed that LPS induced the synthesis of secreted IRAP that was released, whereas the majority of the protein induced by PMA remained cell-associated. Reverse transcriptase-polymerase chain reaction amplification demonstrated that although LPS and PMA induced both transcripts, LPS preferentially induced secreted IRAP, whereas PMA differentially induced intracellular IRAP mRNA. Fibroblasts synthesize at least two different forms of IRAP depending on the inducing signal, and may regulate the inflammatory response by dampening the proinflammatory effects of IL-1 via a negative feedback mechanism with IRAP. The relative importance of fibroblast sIRAP vs intracellular IRAP in regulating the inflammatory response by the connective tissue remains to be determined.
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PMID:Regulation of expression of IL-1 receptor antagonist protein in human synovial and dermal fibroblasts. 847 46

Peripheral lymphoid tissues contain a fibroblastic cell type referred to as stromal cells or reticulum cells which interact with lymphocytes as part of the lymphoid microenvironment. After isolation from human tonsils and expansion in vitro we analyzed the surface phenotype, extracellular matrix components, cytoskeletal products, cytokine production, binding and functional interaction with B lymphocytes of in vitro cultured stromal cells (HTSC) both in resting condition and after activation with tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. Our results show that HTSC do not express specific myeloid, lymphoid, endothelial or epithelial markers. HTSC express CD54 (ICAM-1), CD49a (VLA-1), CD49b (VLA-2), CD49c (VLA-3), CD49e (VLA-5), CD49f (VLA-6), CD29, CD51, CD44 and produce vinculin, beta-tubulin, alpha-actin, vimentin, fibronectin, laminin and collagen types I, III and IV. Activation of HTSC up-regulated CD54 (ICAM-1) and induced HLA-DR and CD106 (VCAM-1). HTSC constitutively produce interleukin (IL)-6 which is enhanced upon activation with TNF-alpha. IL-8 and granulocyte/macrophage colony-stimulating factor are detected only in the supernatants of activated HTSC. Reverse transcriptase polymerase chain reaction analysis revealed that HTSC display mRNA for IL-1 alpha, leukemia inhibitory factor and IL-7. The adhesion of tonsillar B lymphocytes to activated HTSC is mediated by CD11a/CD18 and CD54. Furthermore, HTSC can induce maximal proliferation of IL-2-activated B lymphocytes cocultured in direct cell-cell contact with HTSC. These results clearly distinguish in vitro cultured HTSC from common fibroblasts and other non-lymphoid elements present in the lymphoid parenchyma, such as follicular dendritic cells, and show that HTSC actively participate in the lymphoid microenvironment. In vitro cultures of HTSC could therefore be a useful model system for detailed analysis of the interactions between stromal cells and lymphocytes under physiological and pathological conditions.
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PMID:In vitro cultured stromal cells from human tonsils display a distinct phenotype and induce B cell adhesion and proliferation. 856 62

Human peritoneal mesothelial cells (HPMC) respond to tumor necrosis factor alpha (TNF alpha) by releasing various cytokines that may activate the endothelium and induce recruitment of leukocytes during peristonitis. We characterized the receptors for TNF on HPMC to elucidate their functions in peritonitis. Scatchard analysis determined the presence of 70 x 10(3) TNF receptors/cell with a kDa of 0.44 nM. TNF receptor 1 (TNF-R1, p55) and TNF-R2 (p75) mRNA were demonstrated by reverse-transcriptase-PCR (RT-PCR). TNF-R1 protein was solely detected by flow cytometry (FCM). Interleukin-1 alpha (IL-1 alpha) induced down-regulation of TNF-R1. This was concomitant with accumulation of soluble TNF-R1 (sTNF-R1) detected by specific ELISA. LPS had a lower TNF-R1-shedding activity while TNF alpha did not induce shedding. The IL-1-induced-sTNF-R1-shedding was suppressed by the protein-kinase-A (PKA) inhibitor, H-8, or by H-7, the inhibitor of both PKC and PKA, but not by the specific PKC inhibitor GF. These experiments suggest a role for PKA in the IL-1-shedding signal. No change in TNF-R1 mRNA levels was observed after IL-1 alpha or TNF alpha stimulation while TNF-R2 (p75) mRNA basal levels transiently increased three to fivefold, reaching a peak after four hours followed by an accumulation of sTNF-R2 in the supernatant. Our data suggest that the main receptor expressed on HPMC is TNF-R1. Down-regulation and shedding of TNF-R1 induced by IL-1, and the transient expression of TNF-R2 induced by IL-1 and TNF, may regulate the responses to TNF by HPMC. These results may be important in understanding the inflammatory process of peritonitis were TNF plays a major role.
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PMID:TNF-receptors on human peritoneal mesothelial cells: regulation of receptor levels and shedding by IL-1 alpha and TNF alpha. 880 91

A new immunomodulating agent, imiquimod, has been reported to have antiviral and antitumor activities in animal models. S-28463 (4-amino-2-ethoxymethyl-alpha, alpha-dimethyl-1H-imidazo[4, 5-c]quinoline-1-ethanol), an analog of imiquimod, has more potent antiviral activity in animals than imiquimod. It has also been shown to be more potent at inducing cytokines in human blood in vitro. However, its precise role as an immunomodulator in the skin has not been determined. We investigated the effect of S-28463 on human keratinocyte (KC) production of interferon-alpha (IFN-alpha) and other proinflammatory cytokines, including interleukin (IL)-1alpha, IL-8, and tumor necrosis factor-alpha (TNF-alpha). Human KC were incubated with S-28463 at two concentrations (1 microgram/ml and 10 micrograms/ml) for 6 h. Cytokine gene expression was analyzed by reverse-transcriptase PCR. In human KC, S-28463 stimulated significant increases in IFN-alpha mRNA at both concentrations. IL-1alpha mRNA increased 1.4-fold at 10 micrograms/ml. IL-8 mRNA was upregulated 2.5-fold at 10 micrograms/ml. Twenty-four hours after treatment, IL-1 alpha, IL-8, and TNF-alpha protein were increased, but IFN-alpha was below the level of detection. These results suggest that in the skin, S-28463-induced-IL-1 alpha, IL-8, and TNF-alpha production may be involved in the immunomodulating action of S-28463.
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PMID:Effect of a novel topical immunomodulator, S-28463, on keratinocyte cytokine gene expression and production. 883 22


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