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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is accumulating evidence that peptides derived from the catalytic subunit of human telomerase reverse transcriptase (hTERT) are specifically recognized by CD8+ cytotoxic T lymphocytes. We investigated the cytotoxicity of a human leukocyte antigen (HLA)-A*2402-restricted hTERT-derived peptide 461-469 (hTERT461)-specific CD8+ T-cell clone, designated as K3-1, established from a healthy donor by repetitive peptide stimulation. This clone exhibited cytotoxicity against 4 out of 6 HLA-A24-positive lung cancer cell lines with positive telomerase activity but not 4 HLA-A24-negative examples. When the target cells were pretreated with 100 U/ml of interferon (IFN)-gamma for 48 hr, the susceptibility to K3-1 increased with PC9 cells but unexpectedly decreased with LU99 cells. However, in both cell lines, the expression of molecules associated with epitope presentation such as HLA-A24, transporters associated with antigen processing, low molecular weight polypeptide 7 and proteasome activator 28 was similarly increased after IFN-gamma treatment. Results of CTL assays using acid-extracted peptides indicated that the epitope increased on PC9 cells but not on LU99 cells after IFN-gamma treatment. Semi-quantitative reverse transcriptase polymerase chain reaction disclosed that the expression of hTERT was attenuated in LU99 but not in PC9 cells, accounting for the decreased cytotoxicity mediated by K3-1. The attenuation of the hTERT expression and K3-1-mediated cell lysis after IFN-gamma treatment was also observed in primary adenocarcinoma cells obtained from pulmonary fluid of a lung cancer patient. Our data underline the utility of peptide hTERT461 in immunotherapy for lung cancer, as with other malignancies reported earlier, and suggest that modulation of hTERT expression by IFN-gamma needs to be taken into account in therapeutic approach.
...
PMID:Interferon-gamma differentially regulates susceptibility of lung cancer cells to telomerase-specific cytotoxic T lymphocytes. 1509 6

To compare CC chemokine mRNA levels from native peripheral blood mononucleated cells (PBMCs) before and 6 months after the initiation of two different regimens of highly active antiretroviral therapy (HAART), we treated group 1 (n = 11) with two nucleoside analogues and the protease inhibitor (PI) indinavir boosted by ritonavir (800/100 mg b.i.d.); group 2 (n = 8) was treated with the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz instead of PI. CC chemokine mRNA levels (regulated upon T cell activation expressed secreted [RANTES], macrophage inhibitory protein [MIP]-1alpha, MIP-1beta, monocyte chemotactic protein [MCP]-1, MCP-2) were quantified from PBMCs before and 6 months after the initiation of HAART using a reverse transcription/real-time polymerase chain reaction (PCR) assay. The mRNA levels of MCP-1 and MCP-2 were significantly decreased in both groups (P < 0.05), while MIP-1alpha and MIP-1beta were decreased significantly only in the PI-treated group, but not in the NNRTI group. A moderate decrease of RANTES was observed in both treatment groups. The data suggest that HAART regimens containing either NNRTI or PI are not equivalent with regard to modification of CC chemokine mRNA profiles.
...
PMID:Chemokine mRNA levels in mononucleated cells of HIV-infected patients before and after initiation of PI- versus NNRTI-containing HAART. 1516 2

The full-length cDNA of porcine genes (PSME1 and PSME2) encoding proteasome activators PA28alpha- and beta-subunits were obtained by the rapid amplification of cDNA ends (RACE). The nucleotide sequences and the predicted protein sequences share high sequence identity with their mammalian counterparts. The reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that porcine PSME1 and PSME2 genes are expressed in all eight tissues studied (liver, spleen, bladder, small intestine, kidney, heart, skeletal muscle and lung). The full-length genomic DNA of the porcine PSME1 and PSME2 genes were amplified by PCR. These two genes shared the same structure and were similar in size. A C/T single nucleotide polymorphism in PSME1 intron 8 detected as an SphI PCR-restriction fragment length polymorphism (PCR-RFLP) shows allele frequency differences between Meishan, Tibetan, Large White, Qingping, and Duroc pigs. The association analysis using two experimental GY selection lines selected for growth rate or leanness suggested that the PSME1 genotype was associated with weaning weight. Analyses of somatic cell hybrid (SCHP) and radiation hybrid (IMpRH) panels revealed that both genes map to SSC7q15.3-q21 and closely linked to the T-cell receptor alpha (TCRA) gene.
...
PMID:Sequence characterization, polymorphism and chromosomal localizations of the porcine PSME1 and PSME2 genes. 1537 39

Since the discovery of HIV approximately 20 years ago, more than 60 million individuals have been infected, and AIDS still remains one of the most devastating diseases humankind has ever faced. Unfortunately, there is little hope that an effective vaccine will be developed in the near future. Current antiretroviral treatment is based on drugs that either target the viral enzymes (protease and reverse transcriptase) or the attachment and entry of the virus. Although the introduction of highly active antiretroviral therapy in the mid-1990s has led to a profound reduction in HIV-related morbidity and mortality, the complete eradication of the virus from infected individuals has never been achieved. In addition, these antiviral drugs can induce serious adverse effects, particularly when administered in combination over prolonged treatment periods. A further drawback to these treatments is that with the high mutation rate of HIV, drug-resistant mutants are evolving, particularly when antiretroviral treatment only suppresses virus replication to marginal levels in latently infected cells making up the virus reservoirs in vivo. Cellular genes have much lower mutation rates, and drug-mediated modulation of specific cellular pathways represents an attractive antiviral strategy. Recent findings showing that proteasome inhibitors interfere with budding, maturation and infectivity of HIV have triggered intensive investigation of the hitherto unappreciated function of the ubiquitin-proteasome system in HIV replication. It was also observed that, like several other retroviruses, HIV-1 virions contain a small amount of mono-ubiquitinylated Gag proteins. Currently, two E3-type ubiquitin ligases, in addition to one E3-like protein, have been identified as regulators of HIV budding. These ligases might represent interesting targets for therapeutic intervention.
...
PMID:The ubiquitin-proteasome system in HIV replication: potential targets for antiretroviral therapy. 1575 58

Uncertainty regarding the causality of human papillomaviruses (HPVs) in squamous cell carcinoma of the head and neck (SCCHN) necessitates better in vitro models. We carried out molecular analyses of a novel, naturally HPV-16-transformed SCCHN cell line (UPCI:SCC090) and show high copy number of HPV-16 DNA, present in a head to tail, tandemly repeated integrated state. Sequence analysis of the HPV-16 long control region (LCR) in UPCI:SCC090 revealed a deletion of 163 bp, removing a portion of the enhancer sequence, including the binding sites for the transcription factors YY1 and NF1. The E6 and E7 oncogenes of HPV-16 are expressed at high levels in this cell lines, as determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). UPCI:SCC090 contains wild-type tumour suppressor TP53 gene, and undetectable p53 protein, except after treatment with cisplatin, specific proteasome inhibitors or by E6 RNA interference, suggesting E6-dependent degradation of p53 in this cell line. The results of our studies are consistent with a causative role of HPV-16 in the pathogenesis of SCCHN.
...
PMID:Human papillomavirus-16 associated squamous cell carcinoma of the head and neck (SCCHN): a natural disease model provides insights into viral carcinogenesis. 1576 58

Atrophy of skeletal muscle is common in patients with cancer and results in increased morbidity and mortality. In order to design effective therapy the mechanism by which this occurs needs to be elucidated. Most studies suggest that the ubiquitin-proteasome proteolytic pathway is most important in intracellular proteolysis, although there have been no reports on the activity of this pathway in patients with different extents of weight loss. In this report the expression of the ubiquitin-proteasome pathway in rectus abdominis muscle has been determined in cancer patients with weight loss of 0-34% using a competitive reverse transcriptase polymerase chain reaction to measure expression of mRNA for proteasome subunits C2 and C5, while protein expression has been determined by western blotting. Overall, both C2 and C5 gene expression was increased by about three-fold in skeletal muscle of cachectic cancer patients (average weight loss 14.5+/-2.5%), compared with that in patients without weight loss, with or without cancer. The level of gene expression was dependent on the amount of weight loss, increasing maximally for both proteasome subunits in patients with weight loss of 12-19%. Further increases in weight loss reduced expression of mRNA for both proteasome subunits, although it was still elevated in comparison with patients with no weight loss. There was no evidence for an increase in expression at weight losses less than 10%. There was a good correlation between expression of proteasome 20Salpha subunits, detected by western blotting, and C2 and C5 mRNA, showing that increased gene expression resulted in increased protein synthesis. Expression of the ubiquitin conjugating enzyme, E2(14k), with weight loss followed a similar pattern to that of proteasome subunits. These results suggest variations in the expression of key components of the ubiquitin-proteasome pathway with weight loss of cancer patients, and suggest that another mechanism of protein degradation must be operative for patients with weight loss less than 10%.
...
PMID:Increased expression of proteasome subunits in skeletal muscle of cancer patients with weight loss. 1612 16

Muscle protein degradation is thought to play a major role in muscle atrophy in cancer cachexia. To investigate the importance of the ubiquitin-proteasome pathway, which has been suggested to be the main degradative pathway mediating progressive protein loss in cachexia, the expression of mRNA for proteasome subunits C2 and C5 as well as the ubiquitin-conjugating enzyme, E2(14k), has been determined in gastrocnemius and pectoral muscles of mice bearing the MAC16 adenocarcinoma, using competitive quantitative reverse transcriptase polymerase chain reaction. Protein levels of proteasome subunits and E2(14k) were determined by immunoblotting, to ensure changes in mRNA were reflected in changes in protein expression. Muscle weights correlated linearly with weight loss during the course of the study. There was a good correlation between expression of C2 and E2(14k) mRNA and protein levels in gastrocnemius muscle with increases of 6-8-fold for C2 and two-fold for E2(14k) between 12 and 20% weight loss, followed by a decrease in expression at weight losses of 25-27%, although loss of muscle protein continued. In contrast, expression of C5 mRNA only increased two-fold and was elevated similarly at all weight losses between 7.5 and 27%. Both proteasome functional activity, and proteasome-specific tyrosine release as a measure of total protein degradation was also maximal at 18-20% weight loss and decreased at higher weight loss. Proteasome expression in pectoral muscle followed a different pattern with increases in C2 and C5 and E2(14k) mRNA only being seen at weight losses above 17%, although muscle loss increased progressively with increasing weight loss. These results suggest that activation of the ubiquitin-proteasome pathway plays a major role in protein loss in gastrocnemius muscle, up to 20% weight loss, but that other factors such as depression in protein synthesis may play a more important role at higher weight loss.
...
PMID:Expression of the ubiquitin-proteasome pathway and muscle loss in experimental cancer cachexia. 1616 Jun 95

Acquisition of drug-resistance conferring mutations leads to an enhanced degradation of HIV-1 reverse transcriptase (RT) affecting its immunogenicity. The mechanism of this degradation is not known. We investigated the input of proteasome in this degradation, and explored a possibility to enhance the proteasomal degradation of RTs to potentiate the immunogenic peformance of RT genes. To this end, a C-terminal fusion was made of RT with ornithine decarboxylase (ODC) that is rapidly degraded by proteasome in an ubiquitine-independent fashion. Eukaryotic cells were transiently transfected with the genes for wild-type (wt) RT, multi-drug-resistant (MDR) RT, and their chimeras with ODC. RT expression in the presence or absence of the proteasome inhibitors MG132 and epoxomicin was quantified by Western blotting. Treatment with MG132 led to a two-fold increase in the level of wtRT, and a four-fold increase in the level of MDR-RT accumulation. Treatment with epoxomicin had virtually no effect on the accumulation of wtRT, while stabilizing MDR-RT two-fold. Since epoxomicin is a more specific proteasome inhibitor, it indicated that degradation of wtRT may not be solely proteasomal. Fusion to ODC considerably decreased the intracellular levels of both RT-ODC and MDR-RT-ODC as compared to parental proteins. MG132 treatment increased the intracellular RT-ODC content 20-fold (up the level of the MG132-treated wtRT; 60-80 fg/cell), and epoxomicin treatment, 10-fold as compared to non-treated samples. Thus, attachment of ODC moiety has modified the metabolic pathway of RT targeting it to proteasomal degradation. We are currently testing if this is translated into an enhanced MHC class I performance of wild-type and drug-resistant RTs in gene immunization.
...
PMID:HIV-1 reverse transcriptase targeted for proteasomal degradation as a prototype vaccine against drug-resistant HIV-1. 1618 8

Gentamicin accumulates in the lysosomes of kidney proximal tubular cells and causes apoptosis at clinically relevant doses. Gentamicin-induced apoptosis can be reproduced with cultured renal cells, but only at high extracellular concentrations (1 to 3 mM; 0.4 to 1.2 g/liter) because of its low level of uptake. We recently showed that gentamicin-induced apoptosis in LLC-PK1 cells involves a rapid (2-h) permeabilization of lysosomes and activation of the mitochondrial pathway of apoptosis (10 h). We now examine whether the delivery of gentamicin to the cytosol by electroporation would sensitize LLC-PK1 cells to apoptosis. Cells were subjected to eight pulses (1 ms) at 800 V/cm (square waves) in the presence of gentamicin (3 microM to 3 mM; 1.2 mg/liter to 1.2 g/liter); returned to gentamicin-free medium; and examined at 8 h for their Bax (a marker of mitochondrial pathway activation) contents by Western blotting and competitive reverse transcriptase PCR and at 24 h for apoptosis by 4',6'-diamidino-2'-phenylindole staining (confirmed by electron microscopy) and for necrosis (by determination of lactate dehydrogenase release). Nonelectroporated cells were incubated with gentamicin for 8 and 24 h. Significant increases in Bax levels (8 h) and apoptosis (24 h) were detected with 0.03 mM (13.2 mg/liter) gentamicin in electroporated cells compared with those achieved with 2 mM (928 mg/liter) in incubated cells. The increase in the Bax level was not associated with an increase in the level of its mRNA but was associated with the accumulation of ubiquitinated forms (probably as a result of impairment of its degradation by the proteasome). Assay of cell-associated gentamicin showed a marked, immediate, but transient accumulation in electroporated cells, whereas a slow, steady uptake was detected in incubated cells. The data indicate that cytosolic gentamicin triggers apoptosis. Sequestration of gentamicin in lysosomes would, to some extent, protect against apoptosis.
...
PMID:Gentamicin causes apoptosis at low concentrations in renal LLC-PK1 cells subjected to electroporation. 1656 31

Telomerase counteracts loss of terminal sequences incurred during DNA replication. In S. cerevisiae, telomerase contains an RNA template (TLC1), a reverse transcriptase (Est2p) and at least two regulatory proteins (Est1p and Est3p). Whereas Est2p is constitutively telomere bound, Est1p associates in late S phase, coincident with telomere lengthening. Here we directly demonstrate by coimmunoprecipitation that the composition of telomerase varies during the cell cycle. The absence of Est1p and Est3p from the complex during G1 phase can be attributed to proteasome-dependent degradation of Est1p. Stabilization of Est1p during G1 phase promotes telomerase assembly, revealing a previously uncharacterized role for Est1p in the recruitment of Est3p to the telomerase complex. Though catalytically active, complexes assembled during G1 cannot lengthen telomeres. We conclude that telomerase assembly during G1 phase is regulated by Est1p stability, but assembly is insufficient to activate telomerase at telomeres.
...
PMID:Proteasome-dependent degradation of Est1p regulates the cell cycle-restricted assembly of telomerase in Saccharomyces cerevisiae. 1686 58


<< Previous 1 2 3 4 5 Next >>

---