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)

As a preliminary to transducing human melanoma cells with lymphokine genes, we sought for constitutive gene expression and production of eight interleukins, tumour necrosis factors and granulocyte-colony stimulating factor in 19 human melanoma cell lines. Conversion of RNA into cDNA by reverse transcriptase and polymerase chain reaction (RT-PCR) were employed to evaluate gene expression while enzyme-linked immunosorbent assays (ELISA) or biological assays were used to assess the presence of proteins. No expression of interleukins (IL) 3, 4, and 5 or interferon-gamma RNA was found, while the other cytokines were variably expressed in melanoma lines, with IL-1 alpha, IL-1 beta, IL-6, IL-8, being detectable in most of the lines. At protein level, 10 melanoma cells were tested with ELISA and all were found to produce IL-8, five produced IL-6, two tumour necrosis factor (TNF)-alpha, one IL-1 alpha and two TNF beta. The levels of TNF beta were at the limit of test sensitivity. The amount of various cytokines released by the different lines varied widely. Biological assay with the D10-G4 clone confirmed the presence of IL-1 alpha in the supernatant of melanoma (ME) 10221 and revealed an IL-1 activity in the supernatant of Me 4024/1. The proliferating activity of melanoma supernatants on D10-G4 was inhibited by treatment with polyclonal antibodies against IL-1 alpha but not with antibodies against IL-1 beta. TNF biological activity was tested against the TNF-susceptible fibrosarcoma WEHI 164 clone 13.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of cytokine genes, including IL-6, in human malignant melanoma cell lines. 145 Jun 72

Allelic variation in the DR subregion of the canine major histocompatibility complex (DLA) has been analyzed by nucleic acid sequencing of cDNA clones of DRB genes amplified in vitro by the reverse transcriptase-polymerase chain reaction (RT-PCR). Sequence analysis of a panel of 19 homozygous typing cell dogs representing 12 different DLA-D types (defined by mixed leucocyte reaction) demonstrated the presence of one expressed DRB locus with at least nine distinct alleles in the dog. Unique DLA-DRB alleles were found in the DLA-D types Dw1, Dw3, Dw4, Dw8 (workshop assignments) and D4, D6, D7, D8, and D9 (Seattle assignments). In contrast, the DRB genes of the remaining three DLA-D types (D1, D10, and D16) were identical to those of Dw3/Dw4 (for D1), Dw8 (for D10), and D6 (for D16). The nucleotide sequences of all nine DLA-DRB alleles were typical of functional major histocompatibility complex (MHC) class II beta chains and contained three allelic hypervariable regions (HVRs) in the beta 1 domain at positions 8-16, 26-39, and 57-74. At each variable residue, two to five amino acid substitutions were found. The most polymorphic residues were located at positions 37 (with five amino acid substitutions), 11, 13, 28, and 71 (each with four substitutions). The DLA-DRB alleles had 96%-99% overall nucleotide sequence similarity and 93%-99% amino acid sequence similarity with each other. Cluster analysis of the nucleotide and predicted amino acid sequences subdivided the DLA-DRB alleles into three major allelic groups which may represent the canine counterparts of the supertypic groups described in man.
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PMID:Allelic variation in the DR subregion of the canine major histocompatibility complex. 237 25

HUT-78 cells were infected with a reverse transcriptase (RT)-positive supernatant of a culture of peripheral blood lymphocytes (PBL) from an AIDS patient and then cloned. Of these clones, two have been isolated and characterized. Clone D10 is persistently and productively infected with an HIV variant. The clone F12, in spite of the presence of an integrated full-length HIV provirus, does not release virus particles in the medium. D10 and F12 clones substantially differ in terms of protein pattern; that is, D10 is super-imposable to infected HUT-78 cells, whereas F12 exhibits a decreased uncleaved p55 gag precursor and the presence of uncleaved gp160 and of a unique p19, although they do not show qualitative or quantitative differences in viral RNA synthesis. Restriction patterns of F12 proviral DNA do not show major genomic deletions. These results indicate that F12 clone cells carry an HIV genome with minor mutations that probably affect the correct production of viral proteins at a posttranscriptional level. In addition, the F12 clone is resistant to high-multiplicity superinfection with HIV-1 or HIV-2.
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PMID:Biologic and molecular characterization of producer and nonproducer clones from HUT-78 cells infected with a patient HIV isolate. 276 97

Five repeated topical applications of 2,4-dinitrofluorobenzene to the ears of BALB/c mice resulted in contact dermatitis on the ears as well as significant elevation in dinitrophenol-specific IgE antibody and total IgE in the serum. FK-506 and cyclosporin A inhibited the development of contact dermatitis in terms of skin thickness and histopathological changes of skin lesions. On the contrary, these two drugs potentiated dinitrophenol-specific and total IgE antibody production without affecting IgG and IgM levels in serum. The expression of interferon-gamma mRNA in reverse transcriptase-polymerase chain reaction in the ear was inhibited by FK-506 and cyclosporin A. The expression of interleukin-4 mRNA, germline C epsilon and productive C epsilon in the auricular lymph node was not affected by these two drugs. Contrary to the above in vivo findings, the immunosuppressors, FK-506 and cyclosporin A, inhibited the production of interferon-gamma and interleukin-2 by cultured Th1 cells (1E10.H2 cells) and of interleukin-4 and -5 by Th2 cells (D10.G4.1 cells) in vitro. These results indicated that FK-506 and cyclosporin A selectively inhibited the Th1 cell-mediated contact dermatitis and potentiated the Th2 cell-mediated IgE antibody production in vivo. This potentiation is probably due to the down-regulation of interferon-gamma production by Th1 cells after the treatment with these drugs. However, because FK-506 and cyclosporin A inhibited the production of cytokines by both Th1 and Th2 cells in vitro and these two immunosuppressors showed higher selectivity toward inhibiting Th1 cell-mediated reactions by limitations in vivo experiments.
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PMID:FK-506 and cyclosporin A potentiate the IgE antibody production by contact sensitization with hapten in mice. 933 39

The functional significance of germline transcription of T cell receptor (TCR) beta chain variable (V) region genes is under investigation. The accepted model is that transcriptional activation of germline TCR genes is associated with the rearrangement process during T-cell development. By this model, germline expression of a subset of TCR-Vbeta genes might be expected in early T cells which have not yet undergone rearrangement. Germline transcription of TCR-Vbeta genes was analysed using the reverse transcriptase (RT)-PCR in a clonal T-cell precursor line C1-V13D, a clonal pre-B cell line RAW112 and a mature T helper cell line D10.G4.1. Evidence is presented for germline transcription of TCR-Vbeta8.2 and TCR-Vbeta2.1 genes in all three cell lines, although expression in RAW112 was very weak. C1-V13D cells expressed very high levels of the whole range of transcripts including Vbeta2.1, Vbeta5.1, Vbeta5.2, Vbeta6.1, Vbeta7.1, Vbeta8.1, Vbeta8.2, Vbeta8.3 and Vbeta13.1. However, D10.G4.1 cells expressed a subset of transcripts with apparently lower levels of expression, including Vbeta2.1, Vbeta5.1, Vbeta5.2, Vbeta6.1, Vbeta8.2 and Vbeta8.3. These results raise questions about the significance and possible function of germline transcripts and/or their encoded products in early lymphoid cells and in T cells at different stages of development.
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PMID:Germline transcription of multiple TCR-Vbeta genes in cloned T-cell lines. 1528 49

We measured the effects of non-nucleoside reverse transcriptase (RT) inhibitor-resistant mutations K101E+G190S, on replication fitness and EFV-resistance of HIV(NL4-3). K101E+G190S reduced fitness in the absence of EFV and increased EFV resistance, compared to either single mutant. Unexpectedly, K101E+G190S also replicated more efficiently in the presence of EFV than in its absence. Addition of the nucleoside resistance mutations L74V or M41L+T215Y to K101E+G190S improved fitness and abolished EFV-dependent stimulation of replication. D10, a clinical RT backbone containing M41L+T215Y and K101E+G190S, also demonstrated EFV-dependent stimulation that was dependent on the presence of K101E. These studies demonstrate that non-nucleoside reverse transcriptase inhibitors can stimulate replication of NNRTI-resistant HIV-1 and that nucleoside-resistant mutants can abolish this stimulation. The ability of EFV to stimulate NNRTI-resistant mutants may contribute to the selection of HIV-1 mutants in vivo. These studies have important implications regarding the treatment of HIV-1 with combination nucleoside and non-nucleoside therapies.
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PMID:The non-nucleoside reverse transcriptase inhibitor efavirenz stimulates replication of human immunodeficiency virus type 1 harboring certain non-nucleoside resistance mutations. 2039 80

Artemisinin-based combination therapies (ACTs) are highly effective for the treatment of Plasmodium falciparum malaria, yet their sustained efficacy is threatened by the potential spread of parasite resistance. Recent studies have provided evidence that artemisinins can inhibit the function of PfATP6, the P. falciparum ortholog of the ER calcium pump SERCA, when expressed in Xenopus laevis oocytes. Inhibition was significantly reduced in an L263E variant, which introduced the mammalian residue into a putative drug-binding pocket. To test the hypothesis that this single mutation could decrease P. falciparum susceptibility to artemisinins, we implemented an allelic-exchange strategy to replace the wild-type pfatp6 allele by a variant allele encoding L263E. Transfected P. falciparum clones were screened by PCR analysis for disruption of the endogenous locus and introduction of the mutant L263E allele under the transcriptional control of a calmodulin promoter. Expression of the mutant allele was demonstrated by reverse transcriptase (RT) PCR and verified by sequence analysis. Parasite clones expressing wild-type or L263E variant PfATP6 showed no significant difference in 50% inhibitory concentrations (IC(50)s) for artemisinin or its derivatives dihydroartemisinin and artesunate. Nonetheless, hierarchical clustering analysis revealed a trend toward reduced susceptibility that neared significance (artemisinin, P approximately = 0.1; dihydroartemisinin, P = 0.053 and P = 0.085; and artesunate, P = 0.082 and P = 0.162 for the D10 and 7G8 lines, respectively). Notable differences in the distribution of normalized IC(50)s provided evidence of decreased responsiveness to artemisinin and dihydroartemisinin (P = 0.02 for the D10 and 7G8 lines), but not to artesunate in parasites expressing mutant PfATP6.
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PMID:Investigations into the role of the Plasmodium falciparum SERCA (PfATP6) L263E mutation in artemisinin action and resistance. 2056 62

The genome structure and organization of endogenous caulimovirus sequences from dahlia (Dahlia spp), dahlia mosaic virus (DMV)-D10 from three wild species, D. coccinea (D10-DC), D. sherffii (D10-DS) and D. tenuicaulis (D10-DT), were determined and compared to those from cultivated species of dahlia, D. variabilis (DvEPRS). The complete ca. 7-kb dsDNA genomes of D10-DC, D10-DS, and D10-DT had a structure and organization typical of a caulimovirus and shared 89.3 to 96.6% amino acid sequence identity in various open reading frames (ORF) when compared to DvEPRS. The absence of the aphid transmission factor and the truncated coat protein fused with the reverse transcriptase ORF were common among these DMV-D10 isolates from wild Dahlia species.
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PMID:Genomic characterization of pararetroviral sequences in wild Dahlia spp. in natural habitats. 2183 17

Previous work by our group showed that human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) containing non-nucleoside RT inhibitor (NNRTI) drug resistance mutations has defects in RNase H activity as well as reduced amounts of RT protein in virions. These deficits correlate with replication fitness in the absence of NNRTIs. Viruses with the mutant combination K101E+G190S replicated better in the presence of NNRTIs than in the absence of drug. Stimulation of virus growth by NNRTIs occurred during the early steps of the virus life cycle and was modulated by the RT backbone sequence in which the resistance mutations arose. We wanted to determine what effects RT backbone sequence would have on RT content and polymerization and RNase H activities in the absence of NNRTIs. We compared a NL4-3 RT with K101E+G190S to a patient-isolate RT sequence D10 with K101E+G190S. We show here that, unlike the NL4-3 backbone, the D10 backbone sequence decreased the RNA-dependent DNA polymerization activity of purified recombinant RT compared to WT. In contrast, RTs with the D10 backbone had increased RNase H activity compared to WT and K101E+G190S in the NL4-3 backbone. D10 virions also had increased amounts of RT compared to K101E+G190S in the NL4-3 backbone. We conclude that the backbone sequence of RT can alter the activities of the NNRTI drug-resistant mutant K101E+G190S, and that identification of the amino acids responsible will aid in understanding the mechanism by which NNRTI drug-resistant mutants alter fitness and NNRTIs stimulate HIV-1 virus replication.
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PMID:Reverse transcriptase backbone can alter the polymerization and RNase activities of non-nucleoside reverse transcriptase mutants K101E+G190S. 2380 64

Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus, and an endogenous plant pararetroviral sequence (DvEPRS) were reported in Dahlia spp. DvEPRS, previously referred to as DMV-D10, was originally identified in the US from the cultivated Dahlia variabilis, and has also been found in New Zealand, Lithuania and Egypt, as well as in wild dahlia species growing in their natural habitats in Mexico. Sequence analysis of three new EPRSs from cultivated dahlias from Lithuania [D10-LT; 7,159 nucleotide level (nt)], New Zealand (D10-NZ, 7,156 nt), and the wild species, Dahlia rupicola, from Mexico (D10-DR, 7,133 nt) is reported in this study. The three EPRSs have the structure and organization typical of a caulimovirus species and showed identities among various open reading frames (ORFs) ranging between 71 and 97 % at the nt when compared to those or the known DvEPRS from the US. Examination of a dataset of seven full-length EPRSs obtained to date from cultivated and wild Dahlia spp. provided clues into genetic diversity of these EPRSs from diverse sources of dahlia. Phylogenetic analyses, mutation frequencies, potential recombination events, selection, and fitness were evaluated as evolutionary evidences for genetic variation. Assessment of all ORFs using phylogenomic and population genetics approaches suggests a wide genetic diversity of EPRSs occurring in dahlias. Phylogenetic analyses show that the EPRSs from various sources form one clade indicating a lack of clustering by geographical origin. Grouping of various EPRSs into two host taxa (cultivated vs. wild) shows little divergence with respect to their origin. Population genetic parameters demonstrate negative selection for all ORFs, with the reverse transcriptase region more variable than other ORFs. Recombination events were found which provide evolutionary evidence for genetic diversity among dahlia-associated EPRSs. This study contributes to an increased understanding of molecular population genetics and evolutionary pathways of these reverse transcribing viral elements.
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PMID:Comparative analysis of endogenous plant pararetroviruses in cultivated and wild Dahlia spp. 2435 27


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