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)

The effects of the trichothecene vomitoxin (VT) on the kinetics of cell proliferation and cytokine production were evaluated in murine CD4+ T cells. The CD4+ cultures were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin to activate protein kinase C and increase cytoplasmic free calcium, respectively, in a range of VT concentrations. Total and viable cell counts at 3, 5, 7, 9, and 11 days revealed delayed or impaired cell proliferation in cultures containing between 50 and 100 ng/ml VT, with complete inhibition being observed at 250 and 500 ng/ml of VT. The VT concentration required to inhibit protein synthesis in a 3-day culture by 50% in this model was 40 ng/ml. When enzyme-linked immunosorbent assay (ELISA) was used to quantitate cytokines, IL-2 levels in control cultures were highest at Day 1 and declined rapidly thereafter, whereas, in VT groups, IL-2 levels were highest at Day 3 and remained elevated up to 11 days. IL-2 levels were elevated by continuous exposure to 100-500 ng/ml of VT with more than 100-fold differences being observed between control and 250 ng/ml VT from Days 5 to 11. When IL-2 levels were expressed on a per viable cell basis, increases were even more marked with as much as 6 log differences being observed between the treatments at 250-500 ng/ml VT and control cultures at Day 7. Supernatant IL-4 and IL-5 levels were also elevated by 100 and 250 ng/ml VT in a dose- and time-dependent fashion compared to control cultures, whereas 500 ng/ml VT was inhibitory. When relative IL mRNA abundance was analyzed during the first 3 days of culture by reverse transcriptase-polymerase chain reaction (RT-PCR) in conjunction with Southern hybridization analysis, IL-2 mRNA levels in Days 1, 2 and 3 in cultures containing 100 and 250 ng/ml VT were greater than corresponding controls. IL-2 mRNA abundance in both control and VT-treated cultures was maximal at Day 1 and decreased rapidly thereafter in controls, whereas much slower rates of IL-2 disappearance were noted in 100 and 250 ng/ml of VT. IL-4 and IL-5 mRNA levels at VT doses of 50 and 100 ng/ml were also elevated compared to controls. Pulsed VT (8 to 48 hr) or cycloheximide (4 to 48 hr) exposure of CD4+ cells enhanced supernatant levels of IL-2 but not IL-4 upon incubation for 24 hr in fresh medium. This effect was not persistent. Taken together, VT enhanced and/or delayed peak IL-2, IL-4, and IL-5 gene expression and secretion in CD4+ T cells stimulated with PMA and ionomycin. Remarkably, cytokine superinduction occurred simultaneously with partial or maximal inhibition of cell proliferation.
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PMID:Vomitoxin-mediated IL-2, IL-4, and IL-5 superinduction in murine CD4+ T cells stimulated with phorbol ester calcium ionophore: relation to kinetics of proliferation. 865 34

The effects of the trichothecene vomitoxin (VT) on the kinetics of cell proliferation and cytokine production were evaluated in murine CD4(+) T cells. The CD4(+) cultures were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin to activate protein kinase C and increase cytoplasmic free calcium, respectively, in a range of VT concentrations. Total and viable cell counts at 3, 5, 7, 9, and 11 days revealed delayed or impaired cell proliferation in cultures containing between 50 and 100 ngsolidusml VT, with complete inhibition being observed at 250 and 500 ngsolidusml of VT. The VT concentration required to inhibit protein synthesis in a 3-day culture by 50% in this model was 40 ngsolidusml. When enzyme-linked immunosorbent assay (ELISA) was used to quantitate cytokines, IL-2 levels in control cultures were highest at Day 1 and declined rapidly thereafter, whereas, in VT groups, IL-2 levels were highest at Day 3 and remained elevated up to 11 days. IL-2 levels were elevated by continuous exposure to 100-500 ngsolidusml of VT with more than 100-fold differences being observed between control and 250 ngsolidusml VT from Days 5 to 11. When IL-2 levels were expressed on a per viable cell basis, increases were even more marked with as much as 6 log differences being observed between the treatments at 250-500 ngsolidusml VT and control cultures at Day 7. Supernatant IL-4 and IL-5 levels were also elevated by 100 and 250 ngsolidusml VT in a dose- and time-dependent fashion compared to control cultures, whereas 500 ngsolidusml VT was inhibitory. When relative IL mRNA abundance was analyzed during the first 3 days of culture by reverse transcriptase-polymerase chain reaction (RT-PCR) in conjunction with Southern hybridization analysis, IL-2 mRNA levels in Days 1, 2 and 3 in cultures containing 100 and 250 ngsolidusml VT were greater than corresponding controls. IL-2 mRNA abundance in both control and VT-treated cultures was maximal at Day 1 and decreased rapidly thereafter in controls, whereas much slower rates of IL-2 disappearance were noted in 100 and 250 ngsolidusml of VT. IL-4 and IL-5 mRNA levels at VT doses of 50 and 100 ngsolidusml were also elevated compared to controls. Pulsed VT (8 to 48 hr) or cycloheximide (4 to 48 hr) exposure of CD4(+) cells enhanced supernatant levels of IL-2 but not IL-4 upon incubation for 24 hr in fresh medium. This effect was not persistent. Taken together, VT enhanced andsolidusor delayed peak IL-2, IL-4, and IL-5 gene expression and secretion in CD4(+) T cells stimulated with PMA and ionomycin. Remarkably, cytokine superinduction occurred simultaneously with partial or maximal inhibition of cell proliferation.
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PMID:Vomitoxin-Mediated IL-2, IL-4, and IL-5 Superinduction in Murine CD4+ T Cells Stimulated with Phorbol Ester and Calcium Ionophore: Relation to Kinetics of Proliferation 866 68

We have previously reported that interleukin-1 beta (IL-1) alone induced the transcription of inducible nitric oxide synthase (iNOS) mRNA and nitric oxide (NO) production by isolated neonatal rat cardiac myocytes (CM). The present studies were undertaken to explore the signal transduction pathways involved in IL-1-induced NO production by CM. The addition of IL-1 to CM resulted in a peak rise in both adenosine 3',5'-cyclic monophosphate (cAMP) and protein kinase A (PKA) activities by 10 min followed by rapid declines and return to basal levels within 60 min. The PKA inhibitor KT-5720 completely blocked NO-2 production by IL-1-stimulated CM (P < 0.01; n = 12). The protein kinase C (PKC) inhibitor, calphostin C, had no effect on NO2- production by IL-1 stimulated CM [P = not significant (NS); n = 12]. The addition of PKA+cAMP to cytosols derived from IL-1-treated CM did not directly enhance iNOS enzyme activity (P = NS; n = 3). CM treated with IL-1 alone stained positively for iNOS protein by immunohistochemistry. iNOS staining was absent in CM treated with IL-1+KT-5720. KT-5720 resulted in an earlier disappearance of iNOS mRNA from IL-1-treated CM, as detected by semiquantitative reverse transcriptase-polymerase chain reaction. We report for the first time that PKA (but not PKC) activation is required for IL-1-induced NO production by CM.
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PMID:Protein kinase A activation is required for IL-1-induced nitric oxide production by cardiac myocytes. 876 74

Skeletal muscle exhibits a wide range in functional phenotype in response to changes in physiological demands. We have observed that, in response to changes in work patterns, alterations in gene expression of some proteins coincide with changes in adenylyl cyclase (AC) activity [Kraus, W.E., J.P. Longabaugh, and S. B. Liggett. Am. J. Physiol 263 (Endocrinol. Metab. 26): E266-E230, 1992]. We now examine AC isoform transcript prevalence in various rabbit skeletal muscles and in response to changing work demands. Using reverse transcriptase-polymerase chain reaction, we detected type II AC isoform transcripts in rabbit skeletal muscle. Ribonuclease protection analyses revealed that expression of the type II isoform significantly correlated with the percentage of fast-twitch type IIb/IId fibers (r2 = 0.765, P < 0.01). When a fast-twitch muscle was converted to a slow-twitch muscle via chronic electrical pacing, expression of type II AC mRNA significantly decreased. This response occurred 3 days after the onset of stimulation (78% decrease) and was still present after 21 days of stimulation (76% decrease). As type II AC is relatively insensitive to calcium regulation while sensitive to protein kinase C (PKC) signaling, these data provide further impetus for investigations of protein kinase A and PKC cross-talk signaling mechanisms in the regulation of gene expression.
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PMID:Regulation of type II adenylyl cyclase mRNA in rabbit skeletal muscle by chronic motor nerve pacing. 877 18

The mouse adrenocortical Y-1 cell line expresses a high level of neuropeptide Y1 receptor (NPY-Y1). Moreover the receptor density can be up-regulated by dexamethasone or down-regulated by cAMP. To determine whether such regulation occurs at the level of gene expression, Y1 receptor mRNA was measured using a reverse transcriptase-competitive PCR method. Dexamethasone treatment increased Y1 mRNA in Y-1 cells, whereas the cAMP and ACTH decreased it. We also observed that the amount of Y1 receptor RNA was unaffected by phorbol 12-myristate 13-acetate, a protein kinase C stimulator, but was abolished in a cell line expressing apolipoprotein E (apoE). The results indicated that NPY-Y1 receptor mRNA in Y-1 cells is highly regulated by several intracellular messengers. The role of apoE in such regulation is of particular interest in view of evidence that the isoform of the molecule is highly correlated to the age of onset of Alzheimer's disease. The effect observed in the Y-1 cell line which expresses apoE may implicate a possible role of this protein in the process of neuronal death that occurred in the Alzheimer's disease.
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PMID:Neuropeptide Y receptor gene regulation in mouse adrenocortical Y-1 cells. 879 89

Cell cycle progression requires activation of different cyclin-dependent kinases (CDKs) which are positively regulated by cyclins and negatively regulated by CDK inhibitors. Growth inhibition of the Calu-1 lung carcinoma cells induced with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C, is associated with G2/M arrest and induction of expression of a novel, faster-migrating form of p21(WAF1/CIP1/SDI1) (p21) protein, an inhibitor of cyclin-dependent kinases. This faster-migrating p21 protein was also expressed in TPA-treated A549 lung carcinoma cells which also exhibited G2/M arrest but not in TPA-treated U937 leukemia cells, which only expressed a slower-migrating form of p21 protein. However, reverse transcriptase-polymerase chain reaction and Southern analysis demonstrated no evidence of novel splice in TPA-treated Calu-1 cells. On the other hand, immunoblotting analysis demonstrated that the faster-migrating p21 protein could be detected only by peptide antibody directed against the N terminus but not the C terminus, suggestive of truncation of the latter or protein modification that results in the loss of the C-terminal epitope. Correlation of G2/M arrest with expression of the faster-migrating p21 protein suggests that this novel form of p21 protein may be a mediator of G2/M arrest and growth inhibition.
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PMID:Novel form of p21(WAF1/CIP1/SDI1) protein in phorbol ester-induced G2/M arrest. 893 83

Prostratin, a non-tumor-promoting phorbol ester, inhibited human immunodeficiency virus (HIV)-induced cell killing and viral replication in a variety of acutely-infected cell systems. The potency and degree of cytoprotection was dependent on both viral strain and host cell type. Prostratin activated viral expression in two latently-infected cell lines, but had little or no effect on chronically-infected cell lines. Prostratin caused a dose-dependent, but reversible, decrease in CD4 expression in the CEM-SS and MT-2 cell lines. This down-regulation of CD4 was inhibited in a dose-dependent manner by the protein kinase C (PKC) antagonist, staurosporine. In addition, the cytoprotective and cytostatic effects of prostratin in CEM-SS cells acutely infected with HIV-1RF were reversed by bryostatin-1, a PKC agonist. Prostratin had no effect on reverse transcriptase or HIV-1 protease, nor did it inhibit the binding of gp120 to CD4. We conclude that prostratin inhibits HIV cytopathicity and replication through mechanism(s) involving PKC enzyme(s).
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PMID:Antireplicative and anticytopathic activities of prostratin, a non-tumor-promoting phorbol ester, against human immunodeficiency virus (HIV). 902 Oct 50

A homologue of human protein kinase C (PKC)-related kinase-2, PRK2, which had previously escaped identification in normal mammalian tissues, was isolated from rat liver as the protease-activated kinase (PAK) originally named PAK-2. The 130-kDa cytosolic enzyme was purified to homogeneity and shown by tryptic peptide and reverse transcriptase- polymerase chain reaction (RT-PCR)-amplified rat cDNA sequence analyses to be structurally related to the 116-kDa rat hepatic PAK-1/protein kinase N (PKN) and, even more closely (95% sequence identity) to the 130-kDa human PKC-related kinase, PRK2. Rat myeloma RNA was used as the RT-PCR template because of its relative abundance in PAK-2/PRK2 mRNA compared with liver and other rat tissues. The catalytic properties of PAK-2/PRK2 in many respects resembled those of hepatic PAK-1/PKN, but were distinguished by more favorable kinetics with several peptide substrates, and greater sensitivity to PKC pseudosubstrate and polybasic amino acid inhibitors. PAK-2/PRK2 was also activated by lipids, particularly cardiolipin and to a lesser extent by other acidic phospholipids and unsaturated fatty acids. Cardiolipin activation was most evident with autophosphorylation and histone H2B phosphorylation, but only marginally evident with the favored ribosomal S6-(229-239) peptide substrate for the protease-activated kinase activity. It was concluded that PAK-2 is the rat homologue of human PRK2, with biochemical properties distinct from although overlapping those of the PAK-1/PKN/PRK1 isoform.
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PMID:Isolation and characterization of a structural homologue of human PRK2 from rat liver. Distinguishing substrate and lipid activator specificities. 909 45

The differential expression of Rho family of low molecular weight GTP-binding proteins and protein kinase C (PKC) isozymes were examined during differentiation of rat C6 glial cells to astrocytic phenotypes induced by dibutyryl cAMP (dbcAMP)/theophylline. The cells showed rapid and distinct morphological changes, resembling stellate astrocytes at 12 h after the treatment. The treated cells had a round cell body that extended several long processes each with a beaded appearance. In addition to morphological changes, Western blot analysis revealed that S-100 protein, known as a glial cell differentiation marker, increased and reached the maximal level (approximately 6-fold increase) at 24 h following the addition of dbcAMP. In the control experiments with cells cultured in the absence of serum but also without dbcAMP/theophylline, morphological changes were marginal and apparent increases of S-100 protein were not observed by Western blotting. In response to dbcAMP/theophylline treatment, RhoA showed increases in the mRNA level followed by the protein level, as inferred by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting, respectively. Rac1 and Cdc42 proteins were undetectable by Western blot analyses. In PKC isozymes, increases were observed in PKC beta 1, epsilon, and zeta by RT-PCR, and in beta 1 and epsilon by Western blotting. Among them, PKC epsilon showed the most distinct changes. Its mRNA level transiently increased from 3 to 6 h and then decreased even below the basal level at 18 h after the treatment. In contrast, Western blot analysis revealed that PKC epsilon gradually increased time-dependently to 24 h (approximately 6-fold increase), and remained elevated until 48 h. These results suggested that RhoA and PKC epsilon, and probably also PKC beta 1 and PKC zeta, were closely implicated in C6 cell differentiation.
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PMID:Differential expression of Rho family GTP-binding proteins and protein kinase C isozymes during C6 glial cell differentiation. 910 74

We recently identified a developmental decline in protein kinase C (PKC) isoform expression, at the level of the protein, in rat ventricular myocardium. To investigate mechanisms regulating PKC isoform expression in cardiac tissue, this study uses Northern blot analysis to compare the abundance of PKC isoform mRNAs in neonatal and adult rat ventricular myocardium. PKC-epsilon protein and mRNA were detected in both neonatal and adult rat ventricular myocardial preparations. In contrast, coordinate postnatal declines in the abundance of PKC-alpha and PKC-delta proteins and transcripts were identified. An antiserum raised against the COOH-terminal sequence of PKC-zeta detected abundant immunoreactivity in neonatal, but not adult, ventricular myocytes. However, PKC-zeta transcripts were not detectable in the heart either by Northern blot analysis or a reverse transcriptase-polymerase chain reaction approach, indicating that neither the myocytes nor the contaminating cellular elements in the heart express PKC-zeta. Rather, PKC-lambda, another atypical PKC isoform that is structurally highly homologous to PKC-zeta, was detected at the protein and mRNA level in neonatal, but not adult, ventricular myocardium. Taken together, these results establish that developmental declines in calcium-sensitive, novel, and atypical PKC isoforms are paralleled by changes in the levels of the mRNAs encoding these proteins, suggesting transcriptional regulation of PKC during normal cardiac development. The results of this study further identify PKC-lambda as the atypical PKC isoform expressed by the immature ventricle.
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PMID:PKC-lambda is the atypical protein kinase C isoform expressed by immature ventricle. 913 45


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