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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Previous studies have shown that ATP and UTP are able to stimulate phospholipase C (PLC) and proliferation in cultured aortic smooth muscle cells. Here we set out to characterize the receptor responsible, and investigate a possible role for p42 and p44 mitogen activated protein kinase (MAPK) in the proliferative response. 2. The phospholipase C response of spontaneously hypertensive rat (SHR) derived aortic smooth muscle cells in culture showed that the response to ATP was partial compared to the response to UTP. 3. Further studies characterized the responses of the SHR derived cells. UTP was the only full agonist with the SHR cells; UDP gave a partial response while ADP, 2-methythio-ATP and alpha,beta-methylene ATP were essentially ineffective. The response to UDP was almost lost in the presence of hexokinase, consistent with this being due to extracellular conversion to UTP. These observations are inconsistent with the response being mediated by either P2Y1 or P2Y6 receptors. 4. When increasing concentrations of ATP were present with a maximally effective concentration of UTP, the size of the response diminished, consistent with UTP and ATP acting at a single population of receptors for which ATP was a partial agonist. This is inconsistent with a response mainly at P2Y2 receptors. 5. 1321N1 cells transfected with human P2Y4 receptors gave a similar agonist response profile, with ATP being partial compared to UTP, loss of response to UDP with hexokinase treatment, and with the response to UTP diminishing in the presence of increasing concentrations of ATP. 6. Use of the reverse transcriptase-polymerase chain reaction confirmed the presence of mRNA encoding P2Y4 receptors in SHR derived vascular smooth muscle cells. Transcripts for P2Y2, P2Y4 and P2Y6 receptors, but not P2Y1 receptors, were detected. 7. Stimulation of SHR derived cells with UTP enhanced the tyrosine phosphorylation of both p42 and p44 MAPK, and the incorporation of [3H]-thymidine into DNA. Both these responses were diminished in the presence of an inhibitor of activation of MAPK. 8 These results lead to the conclusion that in SHR derived cultured aortic smooth muscle cells, PLC responses to extracellular UTP and ATP are predominantly at P2Y4 receptors, and suggest that these receptors are coupled to mitogenesis via p42/p44 MAPK.
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PMID:Evidence that P2Y4 nucleotide receptors are involved in the regulation of rat aortic smooth muscle cells by UTP and ATP. 969 Aug 62

RAK antigens p120, p42, and p25 exhibit molecular and immunological similarity to the proteins encoded by human immunodeficiency virus type 1 (HIV-1) and are expressed by 95% of breast and gynecological cancer cases in women and prostate cancer cases in men. The binding of an epitope-specific anti-HIV-1 gp120 monoclonal antibody (MAb) (amino acids 308 to 322) to cancer RAK antigens has been found to be inhibited by a peptide derived from variable loop V3 of HIV-1. Breast cancer DNAs of 40 patients were PCR amplified with HIV-1 gp41-derived primers, and all of the samples were found to be positive. The DNA fragments amplified in seven blindly selected breast cancer samples were sequenced. The breast cancer DNA sequences showed at least 90% homology to the HIV-1 gene for gp41. Antisense oligonucleotides complementary to the HIV-1-like sequences inhibited reverse transcriptase activity and inhibited the growth of breast cancer cells in vitro. Viral particles detected in breast cancer cell lines were strongly immunogold labeled with the anti-HIV-1 gp120 MAb. The results obtained strongly suggest that the long-postulated breast cancer virus may, in fact, be related to HIV-1.
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PMID:Human immunodeficiency virus type 1-like DNA sequences and immunoreactive viral particles with unique association with breast cancer. 972 31

The CC chemokine macrophage inflammatory protein-3alpha (MIP-3alpha) is the product of recent electronic cloning efforts, however, little characterization of its spectrum of biological effects has been undertaken. Human eosinophils exhibited pertussis-toxin-sensitive migration in response to human recombinant (hr)MIP-3alpha. Messenger RNA for the MIP-3alpha receptor, CCR-6, and low levels of surface expression were demonstrated by reverse transcriptase-polymerase chain reaction and FACS analysis. Analyses of cell signaling revealed dose-dependent increases in intracellular calcium mobilization, calcium transients that were, however, greatly reduced when compared with MCP-3-induced responses. Further investigations of MIP-3alpha-induced signal transduction revealed time- and dose-dependent, partially pertussis toxin-dependent, increases in phosphorylation of the p42/p44 mitogen-activated protein kinases (MAPK) that occurred at 10- to 100-fold lower concentrations, and that were linked to a phosphoinositide 3-kinase pathway. These results suggest that MIP-3alpha can regulate multiple, parallel signal transduction pathways in eosinophils, and suggest that MAPK activation by MIP-3alpha in eosinophils is a significant signaling pathway for migration induction.
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PMID:MIP-3alpha induces human eosinophil migration and activation of the mitogen-activated protein kinases (p42/p44 MAPK). 1053 25

Although it is known that the pathogenic mechanism of Helicobacter pylori involves the stimulated production of interleukin-8 (IL-8) as an inflammatory mediator, the details of the pathway remain unclear. The role of mitogen-activated protein kinase (MAPK) in IL-8 production by H. pylori has been examined in an in vitro study. IL-8 mRNA expression in gastric epithelial cells (MKN 28) was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). IL-8 production was examined by ELISA. The activation of p38 MAPK was assessed by western blotting. Neither IL-8 mRNA nor activated p38 MAPK or p44/42 MAPK was detected in cells not treated with H. pylori. In contrast, incubation of cells with H. pylori, or IL-1beta, or both, clearly stimulated the expression of IL-8 mRNA within 60 min in a concentration-dependent manner. Phosphorylation of p38 MAPK and p44/p42 MAPK, as well as IL-8 production, occurred within 30 min and 24 hr after co-culturing MKN 28 cells with H. pylori and IL-1beta, respectively. Pretreatment of cells with MAPK inhibitors [1-[7-(4-fluorophenyl)-1,2,3,4-tetra-hydro-8-pyridylpyrazolo[5,1-c][1,2,4]triazin-2-yl]-2-phenylethanedione sulfate monohydrate (FR167653), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580), or 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059)] significantly inhibited IL-8 production stimulated by H. pylori or IL-1beta or both. The combination of H. pylori and IL-1beta additively stimulated IL-8 production. The additive effect of H. pylori and IL-1beta on IL-8 production was inhibited by treatment with a p38 MAPK inhibitor. It was revealed that the culturing of MKN 28 cells with H. pylori significantly stimulates IL-8 production to a degree sufficient for induction of neutrophil chemotaxis via activation of p38 and p44/42 MAPK.
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PMID:Mechanism for Helicobacter pylori stimulation of interleukin-8 production in a gastric epithelial cell line (MKN 28): roles of mitogen-activated protein kinase and interleukin-1beta. 1137 90

Pulmonary fibrosis is a progressive disorder characterized by the loss of alveolar architecture through epithelial and endothelial cell apoptosis and fibroblast proliferation. Recent studies showed that angiotensin-converting enzyme (ACE) activity is increased in fibrotic tissues, and ACE inhibitors administered in vivo ameliorate fibrosis, suggesting that ACE may play a critical role. However, the regulation of ACE expression is not well understood. In the present study, we demonstrate that bleomycin, a chemotherapeutic agent which induces pulmonary fibrosis in animals and humans, increases gene expression of ACE. Treatment of primary bovine pulmonary artery endothelial cells with 0.1 to 1.0 microg/ml bleomycin increased ACE enzymatic activity and ACE mRNA, as monitored by hippuryl-L-histidyl-L-leucine assay and competitive quantitative reverse transcriptase polymerase chain reaction (RT-PCR), respectively. Luciferase reporter constructs showed that upregulation of ACE transcription by bleomycin is mediated through element(s) in the 97-bp ACE promoter. Bleomycin activated p42/p44 mitogen-activated protein kinase (MAPK) and induced nuclear translocation and activation of the early growth response (Egr)-1 transcription factor, a factor previously shown to positively regulate ACE expression. The MAPK kinase1/2 (MEK1/2) inhibitor U0126 blocked MAPK and Egr-1 activation by bleomycin, suggesting that Egr-1 activation is MAPK dependent. These data provide the first evidence that bleomycin activates ACE gene expression through the MAPK pathway and Egr-1.
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PMID:Bleomycin upregulates gene expression of angiotensin-converting enzyme via mitogen-activated protein kinase and early growth response 1 transcription factor. 1171 4

Telomerase, a reverse transcriptase that maintains chromosome ends (telomeres) during successive cell divisions in mitotic cells is present in neuroblasts and early postmitotic embryonic neurons but is absent from adult neurons. The signals that control telomerase levels during development are unknown, as are the functions of telomerase in developing neurons. We now report that telomerase activity and levels of its catalytic subunit telomerase reverse transcriptase (TERT) are increased in embryonic hippocampal neurons by brain-derived neurotrophic factor (BDNF) and a secreted form of beta-amyloid precursor protein (sAPP). BDNF and sAPP promote the survival of the embryonic neurons, and these trophic effects are blocked when TERT production is suppressed using antisense technology. Telomerase is required for the long-term survival of early postmitotic neurons during a time window of approximately 1 week in culture; telomerase is then downregulated and is not required for BDNF and sAPP survival signaling in mature neurons. The increase in telomerase activity and trophic effects of BDNF and sAPP are mediated by phosphatidylinositol-3 kinase and p42/p44 MAP kinases. Our findings demonstrate a requirement for telomerase in the cell survival-promoting actions of BDNF and sAPP in early postmitotic hippocampal neurons, suggesting a previously unknown role for telomerase in mediating the biological actions of neurotrophic factors during brain development.
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PMID:Telomerase mediates the cell survival-promoting actions of brain-derived neurotrophic factor and secreted amyloid precursor protein in developing hippocampal neurons. 1248 64

To elucidate the underlying mechanisms involved in AIDS therapy-induced peripheral neuropathy, we have developed a model of nucleoside analog reverse transcriptase inhibitor-induced painful peripheral neuropathy in the rat, using 2',3'-dideoxycytidine (ddC), 2',3'-dideoxyinosine (ddI) and 2',3'-didehydro-3'-deoxythymidine (d4T), AIDS chemotherapeutic drugs that are also components of AIDS highly active anti-retroviral therapy. Administration of ddC, ddI and d4T produced dose-dependent mechanical hypersensitivity and allodynia. Peripheral administration of inhibitors of protein kinase A, protein kinase C, protein kinase G, p42/p44-mitogen-activated protein kinase (ERK1/2) and nitric oxide synthase, which have demonstrated anti-hyperalgesic effects in other models of metabolic and toxic painful peripheral neuropathies, had no effect on ddC-, ddI- and d4T-induced hypersensitivity. Since suramin, an anti-parasitic and anti-cancer drug, which shares with the anti-retroviral nucleoside analogs, mitochondrial toxicity, altered regulation of intracellular calcium, and a sensory neuropathy in humans, also produced mechanical hypersensitivity that was not sensitive to the above second messenger inhibitors we evaluated the role of intracellular calcium. Intradermal or spinal injection of intracellular calcium modulators (TMB-8 and Quin-2), which had no effect on nociception in control rats, significantly attenuated and together eliminated ddC and suramin-induced mechanical hypersensitivity. In electrophysiology experiments in ddC-treated rats, C-fibers demonstrated alterations in pattern of firing as indicated by changes in the distribution of interspike intervals to sustained suprathreshold stimuli without change in mechanical activation thresholds or in number of action potentials in response to threshold and suprathreshold stimulation. This study provides evidence for a novel, calcium-dependent, mechanism for neuropathic pain in a model of AIDS therapy-induced painful peripheral neuropathy.
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PMID:Novel mechanism of enhanced nociception in a model of AIDS therapy-induced painful peripheral neuropathy in the rat. 1471 1

Mycoplasma mobile glides on a glass surface in the direction of its tapered end by an unknown mechanism. Two large proteins, Gli349 and Gli521, were recently reported to be involved in glass binding and force generation/transmission, respectively, in M. mobile gliding. These proteins are coded tandemly with two other open reading frames (ORFs) in the order p123-gli349-gli521-p42 on the genome. In the present study, reverse transcriptase PCR analysis suggested that these four ORFs are transcribed cistronically. To characterize the p123 gene coding a 123-kDa protein (Gli123) of 1,128 amino acids, we raised polyclonal antibody against the Gli123 protein. Immunoblotting for Gli123 revealed that Gli123 was missing in a mutant strain, m12, which was previously isolated and characterized by a deficiency in glass binding. Sequencing analysis showed a nonsense mutation at the 523rd amino acid of the protein in the m12 mutant. Immunofluorescence microscopy with the polyclonal antibody showed that Gli123 is localized at the head-like protrusion's base, the cell neck, which is specialized for gliding, as observed for Gli349 and Gli521. Localization of the gliding proteins, Gli349 and Gli521, was disturbed in the m12 mutant, suggesting that Gli123 is essential for the positioning of gliding proteins in the cell neck.
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PMID:Identification of a 123-kilodalton protein (Gli123) involved in machinery for gliding motility of Mycoplasma mobile. 1607 2

The aim of this study was to test the selectivity, in-vivo effectiveness, and potential mechanism of action of a linomide analogue (N-phenyl-1,2-dihydro-4-hydroxyl-2-oxo-quinoline-3-carboxamide, Lin05) for inhibition of choroidal neovascularization. The selectivity of Lin05 was tested in cell proliferation assays with human umbilical vein endothelial cells (HUVEC) and a retinal pigmented epithelial cell line(ARPE-19). In-vivo anti-angiogenic effect of Lin05 was investigated utilizing an experimental laser-induced choroidal neovascularization (ECNV) model in adult Brown Norway rats. Western blot and/or reverse transcriptase-PCR was used to test the effect of Lin05 on potential targets. Our results indicate that Lin05 is at least an 8-fold more selective inhibitor of endothelial cell proliferation compared to RPE cells. Systemic administration of Lin05 in an ECNV model was associated with a significant decrease in both vascular leakage on fluorescein angiography and lesion size by histopathology (p = 0.02). No systemic toxicity was detected for Lin05 in major organs such as the liver, lung and kidneys. Lin05 did not inhibit VEGF-induced VEGFR2 (KDR) phosphorylation in HUVEC nor was associated with decreased VEGF gene expression. Also it did not inhibit insulin-like growth factor (IGF-1) and Epidermal Growth Factor (EGF) induced activation of p42/p44 MAPK activation. It inhibited both PDGF- and bFGF-induced p42/p44 MAPK phosphorylation. However, the effect on PDGF was variable in different HUVEC cells. In conclusion, Lin05 is a potential anti-angiogenic agent for the treatment of eye diseases associated with pathological neovascularization. The anti-angiogenic effect of Lin05 is likely through inhibition of bFGF but not through inhibition of the VEGF/KDR pathway.
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PMID:Investigation of the potential utility of a linomide analogue for treatment of choroidal neovascularization. 2105

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus. One contributing factor to DPN is altered neurotrophism due to changes in the synthesis and expression of neurotrophins. Schwann cells (SCs) are the myelin-forming cells of the peripheral nervous system that promote nerve regeneration through the expression and secretion of neurotrophic factors (NTFs). Therefore, in this study, using SCs cultured in the presence of high levels of glucose for 24 h, with and without the p42/p44 mitogen-activated protein kinase (MAPK) inhibitor, PD98059, we investigated the effect of high glucose levels on SCs over a short period of time. The cultured cells were evaluated using 3(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst staining, immunocytochemistry, reverse transcriptase-polymerase chain reaction and western blot analysis. High glucose levels did not promote morphological abnormalities or decrease the viability of SCs. However, high glucose levels enhanced the expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and induced the activation of p42/p44 MAPK in cultured SCs in a dose-dependent manner. Additionally, the phosphorylation of p42/p44 MAPK may be associated with the expression of NTFs by SCs exposed to high glucose conditions; the excessive activation of p42/p44 MAPK inhibited the expression of NTFs. These observations demonstrate that exposure to high glucose levels lead to acutely elevated levels of NGF and BDNF in SCs over a short period of time, which may be involved in the p42/p44 MAPK pathway.
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PMID:High glucose levels increase the expression of neurotrophic factors associated with p-p42/p44 MAPK in Schwann cells in vitro. 2255 24


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