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 polymerase chain reaction (PCR) was used to amplify, clone, and express eight DNA fragments encoding p25, p16, reverse transcriptase (RT) core, C'-terminal RT, N'- and C'-terminals of external (gp70), and transmembrane (gp40) envelope proteins from visna virus infectious recombinant DNA. Efforts were focused on characterizing the nature of the humoral immune response of ovine progressive pneumonia (OPP) virus infected animals and identifying the conserved and prime-reactive antigenic determinants that have potential diagnostic value. This communication reports that the N'-terminal region of gp40 appeared to be the most immunoreactive of the bacterially expressed proteins and could serve as a sensitive immunodiagnostic antigen for the detection of OPP infection.
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PMID:Analysis of antibody response to ovine lentivirus by using viral gene products expressed in a prokaryotic system. 138 77

Visna virus is a retrovirus which replicates in fibroblast-like cells of the sheep choroid plexus through a lytic cycle. Visna virions contain three major low-molecular-weight proteins (p30, p16, and p14) which, together with the genomic RNA and several molecules of reverse transcriptase, constitute the core structure of the virions. The core is surrounded by an envelope containing a major glycoprotein (gp135). By analogy with the oncoviruses, these three groups of structural proteins (i.e., the internal proteins, the envelope glycoprotein, and the reverse transcriptase) are probably encoded by the gag, env, and pol genes, respectively. To elucidate the genetic organization of the visna virus genome and its expression, we studied the synthesis of viral proteins in infected sheep choroid plexus cells. Intracellular viral proteins were detected by immunoprecipitation of pulse-labeled cell extracts with monospecific sera raised against p30, p16, and gp135 and resolution of the proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoprecipitation with anti-p30 and anti-p16 sera allowed the characterization of the 55,000-dalton polypeptide precursor to internal virion proteins p30, p16, and p14 (Pr55(gag)). Tryptic peptide mapping confirmed the precursor-product relationship between Pr55(gag) and the three internal proteins. In addition, a gag-related polypeptide of 150,000 daltons was also detected. This polypeptide, which was less abundant than Pr55(gag), is a likely precursor to the viral reverse transcriptase (Pr150(gag-pol)). Pr55(gag) and Pr150(gag-pol) are not glycosylated. The precursor related to major envelope protein gp135 is a glycosylated polypeptide with an average molecular weight of 150,000 (gPr150(env)). Pulse-chase experiments indicated that gPr150(env) matures into glycoprotein gp135 intracellularly; however, gp135 was never preponderant in cell extracts. The non-glycosylated from of gPr150(env), which accumulated in the presence of 2-deoxy-d-glucose, appeared as a polypeptide of about 100,000 daltons. These results indicated that visna virus codes for the largest non-glycosylated env-related precursor among all of the retroviruses and therefore probably contains the largest env gene.
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PMID:Precursor polypeptides to structural proteins of visna virus. 617 45

We generated monoclonal antibodies (MAB) against feline immunodeficiency virus (FIV) and characterized these MAB by single competition enzyme immunoassays (EIA), immunoblot analysis, and radioimmunoprecipitation. Four MAB identified 3 distinct epitopes of the FIV p24/26 gag major core protein. One MAB recognized the p16/17 gag protein; none recognized envelope proteins. We developed an FIV p26 antigen capture EIA that proved more sensitive (0.5 ng of p26/ml), less expensive, and less time-consuming than reverse transcriptase assay. The same MAB were used to develop an antibody EIA specific for FIV p26. The MAB and capture assays reported should prove useful in FIV diagnosis and research.
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PMID:Development of monoclonal antibodies and capture immunoassays for feline immunodeficiency virus. 754 55

SIVsm chronically infected cultures were obtained after infection of CEMX174 cells with either SIVsmH3 or SIVsmE660. These phenotypically CD4 cells, formed syncytia but only when cocultivated with CD4+ cells. Single cell clones were derived from these cultures and examined for the production of virus-specific proteins. The majority of the clones expressed SIV p27 antigen and low levels of virus reverse transcriptase activity. Western blot analysis, performed with either monoclonal or polyclonal sera, showed that a chronically infected clone (B7) produced particles which contained envelope (gp135 and gp43), gag precursors and gag proteins (p27, p16 and p8). However, these particles (SIVsmB7) lacked detectable levels of vpx and of integrase, and contained several fusion proteins which expressed viral protease antigens. This defective virus failed to infect established CD4+ cell lines, as well as primary cultures of macrophages and of peripheral blood lymphocytes, obtained both from humans and from rhesus macaques. Lack of infection correlated with lack of viral DNA detection by PCR amplification of genomic DNA extracted from these cell cultures. In addition, SIVsmB7 virus lacked infectivity in vivo. Rhesus macaques inoculated with high concentrations of SIVsmB7 showed no viremia and their PBMC were PCR negative. Thus, B7 cells produced stable, non-infectious virus mutants, which contained env and gag proteins, but lacked detectable amounts of vpx and of enzymes required for virus replication. Due to the high constitutive expression of this virus-like particle, we are now testing this preparation as a vaccine.
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PMID:Properties of virus-like particles produced by SIV-chronically infected human cell clones. 857 47

The tumor suppressor genes p53, retinoblastoma (RB), p16, and p15 encode proteins that regulate the cell cycle cooperatively by controlling the transition from G1 to S phase and may play an important role in cell growth and differentiation. To screen for abnormalities in these genes in cancer, we performed genetic analysis in six human pancreatic cancer and five hepatoma cell lines, by single-strand conformation polymorphism (SSCP) analysis, direct sequencing, and the reverse transcriptase-polymerase chain reaction (RT-PCR). All six pancreatic cancer cell lines had p53 mutations, with the concomitant loss of the other normal allele, encoding wild-type p53. Frequent homozygous deletions were found in p16 and p15, but the RB gene was expressed. Four of the five hepatoma cell lines had p53 mutations with loss of the normal allele and aberrant RB. There were no deletions of p16 and p15 in any of the hepatoma cell lines. These findings suggest that alterations in the p53, p16, and p15 genes are common in human pancreatic cancer cell lines, while p53 or RB mutations are common in hepatoma cell lines. Alterations of these tumor suppressor genes may thus be important features in organ-specific carcinogenesis.
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PMID:Alterations in the tumor suppressor genes p53, RB, p16/MTS1, and p15/MTS2 in human pancreatic cancer and hepatoma cell lines. 905 94

The p16 (CDKN2,MTS1) gene is located at 9p21 and its product, p16, inhibits the cyclin D/CDK4 complex. Loss of heterozygosity on chromosome 9p is very common in human bladder carcinomas and has been found in all stages of lesions, suggesting that it occurs early in bladder tumor progression. Several studies have revealed frequent homozygous deletion of the p16 gene in cell lines, and that such deletions are also common in some types of cancers. In addition, point mutations in the p16 gene have been identified in several types of neoplasia. In the present examination of urinary bladder tumors, no p16 gene mutations were detected, but nine cases out of 23 (39%) showed decreased mRNA expression, revealed by the reverse transcriptase polymerase chain reaction. There were no histological differences apparent between those cases with normal and those with decreased p16 expression. These results indicate that while p16 gene mutations may be rare, changes in the level of the p16 transcripts could play a role in human bladder carcinoma development.
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PMID:Decreased expression of the p16/MTS1 gene without mutation is frequent in human urinary bladder carcinomas. 907 Mar 36

RNA was isolated from 22 squamous cell carcinomas (SCCs) obtained from diverse sites within the head and neck and from matched normal tissue where available. Tissue samples were then screened for expression of RNA from tumor suppressor gene p16 by utilizing semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis. p16-Specific PCR amplification products generated from tumor samples were subject to further analysis by direct DNA sequencing to determine if any tumor sample harbored a p16 mutation. The results show the presence of mutations in 10 of 22 (45%) of the tumor samples. Mutations comprise two identical point mutations, two small deletions (1 bp and 2 bp), one single-nucleotide insertion, four larger deletions, and an insertion/deletion. No mutations in p16 have been identified by analysis of PCR products generated from normal matched tissue, suggesting that p16 alterations are generated by somatic mutation and are not germline in origin. All 22 samples were analyzed additionally by immunohistochemistry for nuclear expression of the retinoblastoma (RB) tumor suppressor gene product. Results show lack of RB nuclear expression in only one sample, suggesting that mutation of RB is an infrequent event in the development of SCC of the head and neck (SCCHN).
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PMID:Frequent mutation of p16 in squamous cell carcinoma of the head and neck. 962 11

The Ewing family of tumors has been defined by the presence of an EWS-ets gene rearrangement. Using molecular techniques for the visualization of this aberration, several tumors of unusual location and histology were recently identified and added to this group. Increasing experimental data suggest that EWS-ets fusions act as transforming transcription factors. Subtractive screening of transgenic fibroblasts has led to the identification of potential targets. The authentic cellular context for these aberrant gene products is still unknown and may be diverse, however. Clinical heterogeneity has stimulated a search for genetic factors that may relate to treatment response. The effect of the EWS-ets fusion transcript structure on localized disease has been recently confirmed and frequent p16 tumor suppressor alterations have been described. The presence of metastases at diagnosis as the major predictor of outcome has been assessed on a submicroscopic level by reverse transcriptase-polymerase chain reaction. Problems arising from these studies are discussed, although the biological basis for variable disease extension remains obscure.
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PMID:Ewing's sarcoma and peripheral primitive neuroectodermal tumors after their genetic union. 970 1

Transforming growth factor-beta1 (TGFbeta1) is inhibitory to most epithelia, but its role in the control of proliferation of prostatic epithelium is unclear. In some cells, TGFbeta1 inhibition is achieved by up-regulation of cyclin-dependent kinase (cdk) inhibitors including p15, p21 and p27. Our aims were to determine whether the effects of TGFbeta1 on human prostatic epithelial cell cycle kinetics were mediated by alterations in the levels of the cdk inhibitors p15, p16, p21 and p27 and hypo-phosphorylated retinoblastoma protein (Rb). Human prostatic epithelial cells in primary culture were grown in the presence of TGFbeta1 (0-10 ng/ml) for up to 4 days and proliferation assessed using a [3H]thymidine uptake assay. Levels of p15, p16, p21 and p27 were measured at both mRNA and protein level by means of a reverse transcriptase PCR-based assay and Western analysis. Rb and cdk2 levels were measured. Exogenous TGFbeta1 (0-5 ng/ml) inhibited proliferation. This was associated with blocking of the cell cycle at G1, and up to 4-fold increases in p15, p21 and p27 mRNA levels, but no change was observed in p16 mRNA levels; these changes were not blocked by cycloheximide. Increased levels of p15, p21 and p27 protein were also accompanied by increased levels of hypo-phosphorylated Rb and decreased cdk2 kinase activity. TGFbeta1 has mainly inhibitory effects on benign human prostatic epithelium, which are caused by up-regulation of cdk inhibitors, hypo-phosphorylation of Rb and delaying of the cell cycle in G1.
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PMID:Transforming growth factor-beta1 up-regulates p15, p21 and p27 and blocks cell cycling in G1 in human prostate epithelium. 992 95

We prospectively analyzed p15 and p16 promoter methylation patterns using methylation-specific polymerase chain reaction (PCR) in patients with adult and childhood acute leukemias and studied the association of methylation patterns with chromosomal abnormalities and prognostic variables. In nearly all French-American-British leukemia subtypes, we found p15 methylation in bone marrow or peripheral blood cells from 58% (46/79) of patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), or acute biphenotypic leukemia (ABL). An identical alteration was detected in blood plasma from 11 of 12 of these patients (92%). We also demonstrated for the first time concomitant p16 and p15 methylation in 22% (8/37) of adults with AML or ALL, exclusively in those with M2, M4, or L2 subtypes. According to cytogenetic data from 35 patients with ALL, AML, or ABL, 82% (14/17) of those with unmethylated p15 alleles had normal karyotypes or hyperdiploidies associated with a favorable prognosis. Conversely, 44% (8/18) of patients with p15 methylation had chromosomal translocations, inversions, or deletions, suggesting an interplay of these abnormalities with p15 methylation. As a prognostic marker for disease monitoring, p15 methylation appears to be more widely applicable than BCR-ABL, AF4-MLL, and AML1-ETO transcripts, which were detectable in only 8% (4/48) of patients by reverse transcriptase-PCR. Thirty-nine of 43 blood samples (91%) sequentially collected from 12 patients with AML, ALL, or ABL showed p15 methylation status in excellent concordance with morphologic disease stage. Early detection of p15 methylation at apparent remission or its acquisition during follow-up may prove valuable for predicting relapse. Overall survival of patients with p15 methylation was notably shortened among 38 adults with AML and 12 adults with ALL. Aberrant p15 methylation may have important prognostic implications for clinical monitoring and risk assessment. (Blood. 2000;95:1942-1949)
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PMID:Aberrant p15 promoter methylation in adult and childhood acute leukemias of nearly all morphologic subtypes: potential prognostic implications. 1104 32


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