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 expression of cytokine mRNAs in tumor tissue, normal mucosa, and peripheral blood mononuclear cells (PBMCs) was studied in 12 patients with colorectal cancer undergoing surgical resection, to characterize local immune conditions. mRNA transcripts for interleukin (IL)-1 beta, IL-2, IL-2-R(p55), IL-4, IL-5, IL-6, and IL-10 were detected using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. IL-6 mRNA was expressed in tumor tissue in 83% of the cases but only in one case in normal mucosa (p < 0.001); serum levels of IL-6 did not show any correlation with IL-6 mRNA; IL-1 beta transcripts were present in all tumor tissue samples; no IL-4 expression was detected; IL-2 mRNA was only present in two tumors; IL-2R(p55) mRNA was found in 58% of tumors but not in normal mucosae (p = 0.005). The expression of IL-10 suggests that it does not play a central role in colorectal cancer immunosuppression, and cytokine expression in PBMCs indicates a different and independent activation. This study suggests a pattern of expression of inflammatory cytokines in the tumor microenvironment, probably produced by infiltrating immune cells. The absence of the specific immune-activating cytokines, IL-2 and IL-4, could indicate an impairment of the anticancer immune response; IL-2R results confirm the dysregulation of the IL-2/IL-2R activation pathway. These findings may lead to a better understanding of the role of cytokines and especially IL-6 at the tumor site and hence their importance in developing an effective immunotherapy.
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PMID:Local expression of cytokines in human colorectal carcinoma: evidence of specific interleukin-6 gene expression. 992 96

Rice tungro bacilliform virus (RTBV) is a plant pararetrovirus and member of the badnavirus subgroup. Open reading frame (ORF) 3 encodes the viral capsid protein, protease (PR), and reverse transcriptase (RT). A DNA fragment of ORF 3 that contains PR and RT sequences was previously expressed in insect cells to produce the PR/RT polyprotein that was processed to yield p62 and p55. p62 and p55 share common N-terminal amino acid sequences and exhibit reverse transcriptase activity. Mass spectrometry was employed to determine the precise molecular weight of the p62 and p55 proteins and enabled determination of the C-termini for both proteins. ORFs encoding either p62 or p55 were constructed and expressed in insect cells using the baculoviruses 62R-BBac and 55R-BBac, respectively. The recombinant p62R and p55R proteins were purified separately and shown to have the same enzymatic activities as previously reported for the processed p62 and p55. The putative active site of the PR was mutated (mpr), and the resulting mpr/RT ORF was expressed in insect cells using the baculovirus mpr/RT-BBac. The mpr/RT polyprotein was not processed in insect cells, resulting in the accumulation of the approximately 87-kDa mpr/RT polyprotein. This study further extends the understanding of p62 and p55 and clarifies the role of the RTBV PR in processing of the RT.
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PMID:Analysis of the proteolytic processing and activation of the rice tungro bacilliform virus reverse transcriptase. 1183 2

Suboptimal treatment of human immunodeficiency virus type 1 (HIV-1) infection with nonnucleoside reverse transcriptase inhibitors (NNRTI) often results in the rapid selection of drug-resistant virus. Several amino acid substitutions at position 190 of reverse transcriptase (RT) have been associated with reduced susceptibility to the NNRTI, especially nevirapine (NVP) and efavirenz (EFV). In the present study, the effects of various 190 substitutions observed in viruses obtained from NNRTI-experienced patients were characterized with patient-derived HIV isolates and confirmed with a panel of isogenic viruses. Compared to wild-type HIV, which has a glycine at position 190 (G190), viruses with 190 substitutions (A, C, Q, S, V, E, or T, collectively referred to as G190X substitutions) were markedly less susceptible to NVP and EFV. In contrast, delavirdine (DLV) susceptibility of these G190X viruses increased from 3 to 300-fold (hypersusceptible) or was only slightly decreased. The replication capacity of viruses with certain 190 substitutions (C, Q, V, T, and E) was severely impaired and was correlated with reduced virion-associated RT activity and incomplete protease (PR) processing of the viral p55(gag) polyprotein. These defects were the result of inadequate p160(gagpol) incorporation into virions. Compensatory mutations within RT and PR improved replication capacity, p55(gag) processing, and RT activity, presumably through increased incorporation of p160(gagpol) into virions. We observe an inverse relationship between the degree of NVP and EFV resistance and the impairment of viral replication in viruses with substitutions at 190 in RT. These observations may have important implications for the future design and development of antiretroviral drugs that restrict the outgrowth of resistant variants with high replication capacity.
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PMID:Amino acid substitutions at position 190 of human immunodeficiency virus type 1 reverse transcriptase increase susceptibility to delavirdine and impair virus replication. 1250 65

A purification procedure is described for the isolation of recombinant HIV-2 reverse transcriptase expressed in Escherichia coli. The p68 subunit is expressed, in the absence of induction, and use of a heparin-Sepharose column produces substantially pure protein. Concentration of the homodimeric p68 reverse transcriptase pool, followed by incubation at room temperature for several days, results in full conversion by E. coli proteases to the heterodimer (p68/p55). This extended incubation simplifies the purification process and improves the yield of heterodimeric reverse transcriptase, which shows a truncation of the smaller subunit to 427 residues. The protein is then purified further by hydroxyapatite and gel-filtration chromatography to homogeneity. The HIV-2 RT is active and has been used to produce crystals that diffract to beyond 3.0 A.
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PMID:Cloning, expression, purification, and crystallisation of HIV-2 reverse transcriptase. 1250 79

Virally regulated HIV-1 particles were expressed from DNA plasmids encoding Gag, protease, reverse transcriptase, Vpu, Tat, Rev, and Env. The sequences for integrase, Vpr, Vif, Nef, and the long terminal repeats (LTRs) were deleted. Mutations were engineered into the VLP genome to produce particles deficient in activities associated with viral reverse transcriptase, RNase H, and RNA packaging. Each plasmid efficiently secreted particles from primate cells in vitro and particles were purified from the supernatants and used as immunogens. Mice (BALB/c) were vaccinated intranasally (day 1 and weeks 3 and 6) with purified VLPs and the elicited immunity was compared to particles without Env (Gag(p55)), to soluble monomeric Env(gp120), or to soluble trimerized Env(gp140). Only mice vaccinated with VLPs had robust anti-Env cellular immunity. In contrast, all mice had high titer anti-Env serum antibody (IgG). However, VLP-vaccinated mice had antisera that detected a broader number of linear Env peptides, had anti-Env mucosal IgA and IgG, as well as higher titers of serum neutralizing antibodies. VLPs elicited high titer antibodies that recognized linear regions in V4-C5 and the ectodomain of gp41, but did not recognize V3. These lentiviral VLPs are effective mucosal immunogens that elicit broader immunity against Env determinants in both the systemic and mucosal immune compartments than soluble forms of Env.
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PMID:Membrane embedded HIV-1 envelope on the surface of a virus-like particle elicits broader immune responses than soluble envelopes. 1701 Oct 11

A monoclonal antibody (mAb), P4A10, was made to the canine interleukin-2 receptor alpha chain (IL-2Ralpha; p55; Tac antigen; CD25) to facilitate studies of canine regulatory T-cells (Treg). By non-reduced Western blot, P4A10 bound to a 55kDa protein, the size of human IL-2Ralpha. In flow cytometry assays, it reacted with a minor population of circulating dog CD3(+)CD4(+) T-cells and the majority (>60%) of in vitro PMA-Ionomycin (PMA-IO)-activated canine CD3(+) T-cells. P4A10 recognized a hematopoietic cell population enriched for FoxP3+ cells as measured by flow cytometry. The P4A10-selected fractions of T-cells had significantly increased copy numbers of CD25, FoxP3, IL-10, and TGFbeta as detected by RT-PCR (reverse transcriptase-PCR) compared to the negative fractions. The P4A10-selected cells inhibited (3)H (tritiated) thymidine incorporation in a mixed leukocyte reaction (MLR) containing responders of the same origin. P4A10-selected T-cells from fresh peripheral blood mononuclear cells had less FoxP3 (p=0.07) by qRT-PCR (quantitative RT-PCR) and were less suppressive (p=0.01) than in vitro alloantigen-activated Treg. The mAb P4A10 is specific for canine CD25 and can be used to facilitate studies of CD25+FoxP3+ Treg in this clinically relevant large animal model.
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PMID:A novel monoclonal antibody specific for canine CD25 (P4A10): selection and evaluation of canine Tregs. 2006 May 95


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