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

---

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

Human cells derived from both normal and neoplastic tissues can be infected by Mason-Pfizer monkey virus (MPMV) without accompanying cytopathology. Infection of cell cultures such as human rhabdomyosarcoma (A204) results in a persistenly infected cell line which can be subcultured over 30 sequential culture passages without significant change in phenotype properties according to reverse, transcriptase (RT), MPMV p27 antigen content, virus particle count and infectivity titre. Productive virus infections were established at relatively low virus particle (VP) input multiplicities (p.i.m.; about 0.06 VP/cell) In A204 cell cultures. At higher p.i.m. (about 600 to 6000 VP/cell) newly synthesized virus was detected within 4 days post infection. Although virus production was cumulative following primary infection, after subculture of infected cultures MPVM production was greater during active cell division. Using synchronization techniques, MPMV replication in persistently infected cultures was found to be cell cycle-dependent. The major internal antigen, p27, was synthesized in G2 and newly synthesized virus particles were released predominantly during mitosis and early G1. Colcemid arrest of cells during mitosis inhibited subsequent MPMV release. Consequently, production of extracellular virus depends upon the progression of cells through the mitotic stage. These data, which provided a basic understanding of the virus-host relationship that occurs in primate cells productively infected with MPMV, were used as a guideline for isolating MPMV-like viruses from experimentally and naturally infected Rhesus monkey.
...
PMID:Characterization of infection and replication of Mason-Pfizer monkey virus in human cell cultures. 11 35

A culture of rhesus monkey peripheral blood lymphocytes was divided into two parts; one was kept as an uninfected control, and the other was infected with a strain of simian immunodeficiency virus (SIVmac251) originally isolated from a rhesus monkey that died of a malignant lymphoma associated with acquired immune deficiency syndrome. Both cultures were sampled at successive intervals from 1 to 40 days postinfection. Each sample was subjected to in situ hybridization for detection of viral mRNA, immunocytochemical detection of viral core protein (p27), reverse transcriptase assay, electron microscopy, and immunophenotypic characterization of infected cells. These techniques were used to define viral growth kinetics of this novel lentivirus in peripheral blood lymphocytes. The first evidence of SIVmac251 replication was obtained by an in situ hybridization signal for viral mRNA at 2 days postinoculation. This was followed by detection of viral p27 core protein by immunocytochemistry on day 4. Reverse transcriptase activity above control values was not detected until day 8. Budding particles were not found in the infected cultures until 14 days postinfection. Results of in situ hybridization, immunocytochemistry, and reverse transcriptase assay indicated that two bursts of viral replication occurred during the course of this study. The first, at 3 weeks postinfection, was due to infection and subsequent depletion of CD4+ lymphocytes, while the second, 3 weeks later, resulted from a cycle of replication in CD8+ lymphocytes and the remaining CD4+ cells, culminating in the death of all cells on day 39 postinoculation.
...
PMID:Study of long-term cultures of simian immunodeficiency virus (SIVmac 251)-infected peripheral blood lymphocytes. 169 33

Murine p53 cDNA sequences were cloned into an in vitro expression vector, Protem Hind. Four deletion libraries were generated using Bal31 double-stranded exonuclease; two being made from constructs encoding a fusion protein constructed from SV40 small t sequences and the p53 clone, p27.la; and two from the full length p53 clone, pp53-5. Both 5'- and 3'-terminal deletions of the p53 gene were made. Transcription of these constructs using Escherichia coli RNA polymerase holoenzyme, followed by translation in mRNA-dependent rabbit reticulocyte lysate, gave in vitro, truncated protein products which were immunoprecipitated by a panel of anti-p53 monoclonal antibodies. This approach enabled us to map accurately the binding sites of seven different monoclonal antibodies, demonstrating four distinct antigenic sites on p53. A synthetic peptide was constructed corresponding to the predicted amino acid sequence of one of these epitopes. This peptide competes with the epitope on the full length p53 protein for the relevant monoclonal antibodies and dissociates the corresponding p53/antibody complexes.
...
PMID:Precise epitope mapping of the murine transformation-associated protein, p53. 240 82

Viral protein X (Vpx) is a human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus accessory protein that is packaged into virions in molar amounts equivalent to Gag proteins. To delineate the processes of virus assembly that mediate Vpx packaging, we used a recombinant vaccinia virus-T7 RNA polymerase system to facilitate Gag protein expression, particle assembly, and extracellular release. HIV genes were placed under control of the bacteriophage T7 promoter and transfected into HeLa cells expressing T7 RNA polymerase. Western immunoblot analysis detected p55gag and its cleavage products p39 and p27 in purified particles derived by expression of gag and gag-pol, respectively. In trans expression of vpx with either HIV-2 gag or gag-pol gave rise to virus-like particles that contained Vpx in amounts similar to that detected in HIV-2 virus produced from productively infected T cells. Using C-terminal deletion and truncation mutants of HIV-2 Gag, we mapped the p15 coding sequence for determinants of Vpx packaging. This analysis revealed a region (residues 439 to 497) downstream of the nucleocapsid protein (NC) required for incorporation of Vpx into virions. HIV-1/HIV-2 gag chimeras were constructed to further characterize the requirements for incorporation of Vpx into virions. Chimeric HIV-1/HIV-2 Gag particles consisting of HIV-1 p17 and p24 fused in frame at the C terminus with HIV-2 p15 effectively incorporate Vpx, while chimeric HIV-2/HIV-1 Gag particles consisting of HIV-2 p17 and p27 fused in frame at the C terminus with HIV-1 p15 do not. Expression of a 68-amino-acid sequence of HIV-2 containing residues 439 to 497 fused to the coding regions of HIV-1 p17 and p24 also produced virus-like particles capable of packaging Vpx in amounts similar to that of full-length HIV-2 Gag. Sucrose gradient analysis confirmed particle association of Vpx and Gag proteins. These results demonstrate that the HIV-2 Gag precursor (p55) regulates incorporation of Vpx into virions and indicates that the packaging signal is located within residues 439 to 497.
...
PMID:Localization of the Vpx packaging signal within the C terminus of the human immunodeficiency virus type 2 Gag precursor protein. 808 57

The genomic RNA-1 of red clover necrotic mosaic dianthovirus (RCNMV) contains the heptanucleotide GGAUUUU that precedes the termination codon of the 5' proximal p27 open reading frame (ORF). This heptanucleotide is followed by a sequence with the potential to form a stable, complex secondary structure. Translation of RNA-1 is postulated to utilize a -1 ribosomal frameshifting mechanism to express the 88-kDa viral RNA polymerase. Using site-directed mutagenesis together with cell-free translation to monitor frameshifting and a biological assay of the mutants in plants, we establish the role of the GGAUUUU as the site where -1 ribosomal frameshifting occurs. The frameshifting signal sequence conforms to the simultaneous slippage model. Stop codons flanking the shifty signal are not required for frameshifting but the p27 ORF termination codon is necessary for maintaining optimal infectivity of the virus. Mutations abolishing the RCNMV RNA-1 internal p57 ORF initiation codon did not affect infectivity of the virus, suggesting that this cistron is only expressed in vivo as an 88-kDa ribosomal frameshifting product. Shifty heptanucleotide signals from a number of animal retroviruses and RNA plant viruses facilitate RCNMV frameshifting in vitro. However, only a limited number of the heterologous shifty heptanucleotides were functional in plant cells. We suggest that specific shifty tRNA populations in the cell facilitate viral -1 ribosomal frameshifting. This analysis also suggests that the slippery sequence requirements are not identical in mammalian and in plant systems.
...
PMID:Identification and analysis of the site of -1 ribosomal frameshifting in red clover necrotic mosaic virus. 817 44

The red clover necrotic mosaic virus (RCNMV) genome is split between two single-stranded RNA species termed RNA-1 and RNA-2. RNA-1 directs the synthesis of 88-kDa (p88), 57-kDa (p57), 37-kDa (p37), and 27-kDa (p27) polypeptides and RNA-2 a 35-kDa (p35) polypeptide in vitro. The coding order of the RNA-1 products was determined to be 5'-p27-p57-p37-3'. Antibodies to synthetic peptides representing the carboxyl terminal portions of p27 and p57 immunoprecipitated their respective polypeptides in addition to p88, suggesting that p88 is a fusion protein. A frameshift heptanucleotide sequence element has been identified in RCNMV RNA-1. In addition, a stable stem-loop secondary structure adjacent to the heptanucleotide sequence is predicted. Together, these sequence elements suggest that a ribosomal frameshifting event occurs which allows translational readthrough of the p27 open reading frame into the p57 open reading frame, generating the observed p88 product. An RNA-1 expression construct fusing the p57 and the CP open reading frame was engineered to investigate the ribosomal frameshifting event. CP antibodies immunoprecipitated a fusion protein of the predicted size containing the carboxyl portion of CP. Site-directed mutagenesis of the frameshift element indicates that in vitro, p88 can also be expressed alternatively by suppression of an amber termination codon. Based on these data, we propose that the putative RCNMV RNA polymerase is an 88-kDa polypeptide expressed by a ribosomal frameshifting mechanism similar to those utilized by retroviruses.
...
PMID:Synthesis of the putative red clover necrotic mosaic virus RNA polymerase by ribosomal frameshifting in vitro. 843 66

The RNA polymerase gene of the murine coronavirus mouse hepatitis virus (MHV) encodes a polyprotein of greater than 750 kDa. The amino-terminal cleavage product of the MHV polymerase polyprotein, p28, has been shown to be cleaved from the polyprotein by the virus-encoded protease PCP-1. We aim to identify the MHV-JHM proteolytic products downstream of p28 and to determine which viral proteinase domains are responsible for generating each of them. To this end, we have generated antisera directed at specific MHV-JHM ORF1a regions and have used these antisera to identify six viral proteins, representing a large portion of ORF1a, from MHV-JHM-infected cells. These proteins include p28, p72, p65, p250, p210, and p27.
...
PMID:Maturation of the polymerase polyprotein of the coronavirus MHV strain JHM involves a cascade of proteolytic processing events. 978 75

CD40 ligand (CD40L), expressed on activated T cells, binds its receptor, CD40, on dendritic cells, B cells, and monocytes/ macrophages. Human immunodeficiency virus (HIV)-infected individuals exhibit normal B-cell CD40 expression but diminished expression of CD40L on CD4 + T cells. Thus, we studied recombinant human CD40L (huCD40L) in an in vitro rhesus macaque model of acquired immunodeficiency syndrome (AIDS). huCD40L induced peripheral blood mononuclear cell (PBMC) proliferation independent of mitogenic cytokines and led to a 70% reduction in p27 production by simian immunodeficiency virus (SIV) mac239 infected PBMCs (P < 0.05). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed reduced expression of SIV gag and increased expression of interleukin (IL)-16 mRNA. Supernatants from huCD40L-stimulated PBMC and control cultures contained similar amounts of IL-16, suggesting an intracellular antiviral effect by IL-16. Phytohemagglutinin (PHA)-stimulated PBMCs similarly cultured with huCD40L showed only slight increases in chemokine production (P > 0.05). These results suggest that huCD40L inhibits replication (antigen and mRNA production) of SIVmac239. This response involves huCD40L induction of IL16 mRNA expression and appears to be independent of beta-chemokines.
...
PMID:Recombinant human CD40 ligand inhibits simian immunodeficiency virus replication: a role for interleukin- 16. 1059 85

We induced rat mammary tumors in 7-week-old female Sprague-Dawley rats by intragastric administration of 7,12-dimethylbenz(a)anthracene (DMBA), and analyzed by immunohistochemistry the expression of cyclin D1, cyclin E, p21(Cip1), and p27(Kip1) in carcinomas, atypical tumors, and benign tumors as well as normal mammary glands from the control group. Proliferation status was assessed by immunohistochemistry using bromodeoxyuridine (BrdU). A sequential increase in cyclin D1-, cyclin E-, and p21(Cip1)-positive epithelial cells was observed from normal mammary glands, to atypical tumors, to carcinomas. In contrast, carcinomas showed a significantly lower number of epithelial cells immunoreactive to p27(Kip1) when compared with atypical tumors, benign tumors and normal mammary glands. The immunoreactivities of BrdU, cyclin D1, cyclin E, and p21(Cip1) were positively correlated, whereas that of p27(Kip1) appeared inversely correlated to those of the others. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot analysis were also performed to determine the mRNA and protein levels of cyclins and cyclin-dependent kinase inhibitors in tumors and normal mammary glands. The protein levels for cyclin D1, cyclin E and p21(Cip1) in carcinomas and atypical tumors were significantly higher than those in benign tumors, while normal mammary glands showed negligible expression. On RT-PCR, tumors showed higher mRNA levels of cyclin D1 and cyclin E than those of normal mammary glands. Our results suggest that rat mammary carcinogenesis involves increased expression of cyclin D1, cyclin E, and p21(Cip1), associated with decreased expression of p27(Kip1).
...
PMID:Increased expression of cyclin D1, cyclin E and p21(Cip1) associated with decreased expression of p27(Kip1) in chemically induced rat mammary carcinogenesis. 1112 20

Advanced gastric cancer is often accompanied by metastasis to the peritoneum, resulting in a high mortality rate. Mechanisms involved in gastric cancer metastasis have not been fully clarified because metastasis involves multiple steps and requires a combination of altered expressions of many different genes. Thus, independent analysis of any single gene would be insufficient to understand all of the aspects of gastric cancer peritoneal dissemination. In this study, we performed a global analysis of the differential gene expression of a gastric cancer cell line established from a primary main tumour (SNU-1) and of other cell lines established from the metastasis to the peritoneal cavity (SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB). The application of a high-density cDNA microarray method made it possible to analyse the expression of approximately 21 168 genes. Our examinations of SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB showed that 24 genes were up-regulated and 17 genes down-regulated besides expression sequence tags. The analysis revealed the following altered expression such as: (a) up-regulation of CD44 (cell adhesion), keratins 7, 8, and 14 (epitherial marker), aldehyde dehydrogenase (drug metabolism), CD9 and IP3 receptor type3 (signal transduction); (b) down-regulation of IL2 receptor gamma, IL4-Stat (immune response), p27 (cell cycle) and integrin beta4 (adhesion) in gastric cancer cells from malignant ascites. We then analysed eight gastric cancer cell lines with Northern blot and observed preferential up-regulation and down-regulation of these selected genes in cells prone to peritoneal dissemination. Reverse transcriptase-polymerase chain reaction confirmed that several genes selected by DNA microarray were also overexpressed in clinical samples of malignant ascites. It is therefore considered that these genes may be related to the peritoneal dissemination of gastric cancers. The results of this global gene expression analysis of gastric cancer cells with peritoneal dissemination, promise to provide a new insight into the study of human gastric cancer peritoneal dissemination.
...
PMID:Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites. 1240 56


1 2 Next >>

---