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)

CneMDR1, a gene encoding a protein related to several eukaryotic multidrug resistance (MDR) proteins, was identified, cloned, and characterized from a clinical isolate of Cryptococcus neoformans (Cn) (strain M1-106). Polymerase chain reaction (PCR) amplification of a DNA region encompassing conserved motifs of other MDR-like proteins was initially used to identify and clone CneMDR1. Analysis of the corresponding cDNA revealed an open reading frame punctuated by 16 introns. CneMDR1 encoded a protein (CNEMDR1) containing 1408 amino acids (aa) with a predicted mass of approximately 152kDa. Protein structure predictions suggested the presence of two putative 6-transmembrane (TM) domains as well as two ATP-binding domains, structural characteristics typical of ATP-binding cassette (ABC) proteins. Members of this superfamily, which include MDR proteins, are frequently involved in active transport of a variety of substrates across the cell membrane. Pulsed-field gel electrophoresis revealed the presence of 12 chromosomal bands in this clinical isolate of Cn. CneMDR1 was detected by hybridization on chromosome IV. High-stringency hybridization detected only one MDR-like gene. However, a second MDR-like gene (CneMDR2) was discovered during reverse transcriptase-PCR (RT-PCR) amplification using cDNA.
...
PMID:Cloning and characterization of CneMDR1: a Cryptococcus neoformans gene encoding a protein related to multidrug resistance proteins. 940 67

Polymerase chain reaction and cDNA library screening approaches were employed to identify a putative member of the highly conserved family of ATP-binding cassette transport proteins from Fasciola hepatica. At the predicted protein level, the F. hepatica sequence identified in the present study shares 43% and 36% identity with the Schistosoma mansoni SMDR2 and human MDR1 ATP-binding cassette transport sequences, respectively. Northern blot and reverse transcriptase-PCR analyses have demonstrated that expression of the F. hepatica ABC-transporter homologue is confined to immature parasites. The biochemical basis for the stage-specific expression of the ATP-binding cassette transporter homologue within F. hepatica remains to be determined.
...
PMID:Developmental expression of a Fasciola hepatica sequence homologous to ABC transporters. 977 Jun 23

Several ATP-binding cassette (ABC) transporters are critically involved in cholesterol and phospholipid efflux, reverse cholesterol transport, and play an important role in the development of atherosclerosis. Quantification of ABC mRNA is important in studying the regulation of cellular cholesterol homeostasis and mechanisms related to the pathogenesis of atherosclerosis. We have developed a one-step real time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method for measuring mRNA levels of ABCA1, ABCG1, and ABCA2 in murine tissues using the TaqMan(TM) technology. It has significant methodological benefits when compared to classic Northern blotting or semi-quantitative RT-PCR analysis. Using this method, we found high expression levels of ABCA1 in liver and macrophages, and of ABCG1 in the brain and macrophages. The expression of ABCA1 and ABCG1 were further induced in macrophages loaded with acLDL. In contrast, ABCA2 was expressed exclusively in the brain with low expression levels in the macrophages. This method provides a rapid, highly sensitive, specific, and reproducible quantification of ABC mRNA, and can be performed with nanograms of total RNA sample, thus making it a superior method for studying the regulation of ABC transporters in cholesterol efflux and its role in the pathogenesis of atherosclerosis in murine models.
...
PMID:Rapid quantification of murine ABC mRNAs by real time reverse transcriptase-polymerase chain reaction. 1245 81

Nuclear expression of the Y-box-binding protein (YB-1) has been reported to correlate with the expression of P-glycoprotein in breast cancer and osteosarcoma. Overexpression of the ATP-binding cassette (ABC) superfamily, such as P-glycoprotein/multi-drug resistance (MDR) 1 and MDR-associated protein (MRP) 1, 2 and 3, has been reported in various malignant neoplasms. Fifty-four surgically resected synovial sarcomas were examined immunohistochemically for nuclear expression of YB-1 and intrinsic expression of P-glycoprotein, MRP1, MRP2, and topoisomerase II alpha, and the findings were compared with clinicopathological parameters, proliferative activities as evaluated by MIB-1 labelling index (LI), and the patients' prognoses. In addition, MDR1, MRP1, MRP2, and MRP3 mRNA levels were assessed using a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method in 22 concordant frozen specimens from these cases and the findings were compared with six control skeletal muscle tissues. Independent prognostic factors were investigated using the Cox proportional hazards regression model. Nuclear expression of YB-1 protein correlated with P-glycoprotein expression (p = 0.0126). Moreover, cases with nuclear expression of YB-1 correlated with poor survival (p = 0.0495) and showed a high topoisomerase II alpha labelling index (topo II alpha LI) (p = 0.0056) and a high MIB-1 LI (p = 0.01). Multivariate Cox analysis showed that only the nuclear expression of YB-1 (p = 0.0136) and high American Joint Committee on Cancer (AJCC) stage (ie stage III or IV) (p < 0.0001) were independent factors for poor prognosis, while the expression of the YB-1 responsive gene products examined was not. These results indicate that the nuclear expression of YB-1 protein is associated with P-glycoprotein expression and proliferative activity as shown by the topo II alpha LI and the MIB-1 LI, and that expression of this protein is an important independent prognostic factor in synovial sarcoma.
...
PMID:Nuclear expression of Y-box-binding protein-1 correlates with P-glycoprotein and topoisomerase II alpha expression, and with poor prognosis in synovial sarcoma. 1253 39

A collection of Aspergillus fumigatus mutants highly resistant to itraconazole (RIT) at 100 micro g ml(-1) were selected in vitro (following UV irradiation as a preliminary step) to investigate mechanisms of drug resistance in this clinically important pathogen. Eight of the RIT mutants were found to have a mutation at Gly54 (G54E, -K, or -R) in the azole target gene CYP51A. Primers designed for highly conserved regions of multidrug resistance (MDR) pumps were used in reverse transcriptase PCR amplification reactions to identify novel genes encoding potential MDR efflux pumps in A. fumigatus. Two genes, AfuMDR3 and AfuMDR4, showed prominent changes in expression levels in many RIT mutants and were characterized in more detail. Analysis of the deduced amino acid sequence encoded by AfuMDR3 revealed high similarity to major facilitator superfamily transporters, while AfuMDR4 was a typical member of the ATP-binding cassette superfamily. Real-time quantitative PCR with molecular beacon probes was used to assess expression levels of AfuMDR3 and AfuMDR4. Most RIT mutants showed either constitutive high-level expression of both genes or induction of expression upon exposure to itraconazole. Our results suggest that overexpression of one or both of these newly identified drug efflux pump genes of A. fumigatus and/or selection of drug target site mutations are linked to high-level itraconazole resistance and are mechanistic considerations for the emergence of clinical resistance to itraconazole.
...
PMID:Multiple resistance mechanisms among Aspergillus fumigatus mutants with high-level resistance to itraconazole. 1270 46

The pathogenesis of human immunodeficiency virus (HIV)-associated dementia has been linked to microglial responses after infection. We have recently confirmed expression of several ATP-dependent efflux transporters in microglia, namely, multidrug resistance protein 1 (MRP1) and P-glycoprotein (P-gp). In the present study, we investigated whether cultured rat microglia express two additional MRP family members, rMRP4 and rMRP5. Using reverse transcriptase-polymerase chain reaction, rMRP4 and rMRP5 mRNA was detected in primary cultures of microglia and in a rat microglia cell line, MLS-9. Western blot analysis further confirmed protein expression of the two MRP isoforms in MLS-9 cells. Bis(pivaloxymethyl)-9-(2-phosphonylmethoxyethyl)adenine [bis(POM)PMEA], a lipophilic ester prodrug of the well characterized MRP4 and 5 substrate 9-(2-phosphonylmethoxyethyl)adenine (PMEA), was chosen to examine transport characteristics in MLS-9. Using thin layer chromatography, we verified that more than 90% of radioactivity recovered in MLS-9 loaded with 1 microM [(3)H]bis(POM)PMEA for 1 h under ATP-depleting conditions was converted to PMEA. Efflux of PMEA by MLS-9 cell monolayers was ATP-dependent, glutathione-independent, and significantly inhibited by several MRP inhibitors (i.e., sulfinpyrazone, genistein, indomethacin, and probenecid) as well as the antiretroviral drug azidothymidine-monophosphate. Similar results were not observed in MRP1- or P-gp-overexpressing cell lines, suggesting that PMEA is not a substrate for either P-gp or MRP1. These studies provide further evidence that microglia express multiple subfamilies of ATP-binding cassette transporters (i.e., P-gp, MRP1, MRP4, and MRP5) that could restrict permeation of several different classes of antiretroviral drugs in a brain cellular target of HIV-1 infection.
...
PMID:Multidrug resistance protein (MRP) 4- and MRP 5-mediated efflux of 9-(2-phosphonylmethoxyethyl)adenine by microglia. 1476 2

Streptomyces coelicolor is the prototype for the investigation of antibiotic-producing and differentiating actinomycetes. As soil bacteria, streptomycetes can metabolize a wide variety of carbon sources and are hence vested with various specific permeases. Their activity and regulation substantially determine the nutritional state of the cell and, therefore, influence morphogenesis and antibiotic production. We have surveyed the genome of S. coelicolor A3(2) to provide a thorough description of the carbohydrate uptake systems. Among 81 ATP-binding cassette (ABC) permeases that are present in the genome, we found 45 to encode a putative solute binding protein, an essential feature for carbohydrate permease function. Similarity analysis allowed the prediction of putative ABC systems for transport of cellobiose and cellotriose, alpha-glucosides, lactose, maltose, maltodextrins, ribose, sugar alcohols, xylose, and beta-xylosides. A novel putative bifunctional protein composed of a substrate binding and a membrane-spanning moiety is likely to account for ribose or ribonucleoside uptake. Glucose may be incorporated by a proton-driven symporter of the major facilitator superfamily while a putative sodium-dependent permease of the solute-sodium symporter family may mediate uptake of galactose and a facilitator protein of the major intrinsic protein family may internalize glycerol. Of the predicted gene clusters, reverse transcriptase PCRs showed active gene expression in 8 of 11 systems. Together with the previously surveyed permeases of the phosphotransferase system that accounts for the uptake of fructose and N-acetylglucosamine, the genome of S. coelicolor encodes at least 53 potential carbohydrate uptake systems.
...
PMID:In silico and transcriptional analysis of carbohydrate uptake systems of Streptomyces coelicolor A3(2). 1497 30

Breast cancer resistance protein (BCRP/ABCG2) is a novel member of ATP-binding cassette transporters, which induce multidrug resistance in cancer cells. We previously reported that a high level of BCRP expression in CD4(+) T cells conferred cellular resistance to nucleoside reverse transcriptase inhibitors (NRTIs) of human immunodeficiency virus type 1 (HIV-1). However, this BCRP was found to have a mutation of Arg to Met at position 482 (BCRP(R482M)). The present study demonstrated that the wild-type BCRP (BCRP(WT)) also conferred cellular resistance to NRTIs. MT-4 cells (a CD4(+) T-cell line) highly expressing BCRP(WT) (MT-4/BCRP) were generated and the expression of BCRP(WT) was confirmed by genotypic and phenotypic analyses. Compared to the parental MT-4 cells, MT-4/BCRP cells displayed resistance to zidovudine (AZT) in terms of antiviral activity as well as drug cytotoxicity. In addition, other NRTIs were also less inhibitory to HIV-1 replication in MT-4/BCRP cells than in MT-4 cells. Significant reduction of intracellular AZT accumulation was observed in MT-4/BCRP cells. An analysis for intracellular metabolism of AZT suggested that the resistance was attributed to the increased efflux of AZT and its metabolites in MT-4/BCRP cells. Furthermore, the BCRP-specific inhibitor fumitremorgin C completely restored the reduction of AZT in MT-4/BCRP cells. These results indicate that, like BCRP(R482M), BCRP(WT) also plays an important role in cellular resistance to NRTIs.
...
PMID:Induction of cellular resistance to nucleoside reverse transcriptase inhibitors by the wild-type breast cancer resistance protein. 1534 26

The phenomenon of multidrug resistance (MDR) in various malignant neoplasms has been reported as being caused by one or multiple expressions of ATP-binding cassette (ABC) superfamily protein, including P-glycoprotein/multidrug resistance (MDR) 1 and the MDR protein (MRP) family. However, their expression levels and distribution within soft tissue sarcomas remain controversial. In 86 cases of surgically resected soft tissue sarcoma, intrinsic mRNA levels of MDR1, MRP1, MRP2 and MRP3 were assessed using a quantitative reverse transcriptase-PCR (RT-PCR) method. Moreover, immunohistochemical protein expressions of P-glycoprotein (P-gp), MRP1, MRP2, MRP3 and p53 protein were evaluated in concordant paraffin-embedded material. The mRNA expression and immunohistochemical expression of ABC superfamily transporters were compared to clinicopathologic parameters and proliferative activities as evaluated by the MIB-1-labeling index (LI). Among the various histologic types, malignant peripheral nerve sheath tumor (MPNST) showed significantly high levels of MDR1 (p=0.017) and MRP3 (p=0.0384) mRNA expression, compared to the other tumor types. When the immunohistochemical method was compared to the RT-PCR technique to assess ABC transported expression at the protein and mRNA levels, a significantly close relationship was found between the 2 methods (p<0.05). P-gp expression was significantly correlated with large tumor size (> or =5 cm, p=0.041) and high AJCC stage (stages III and IV) (p=0.0365). Furthermore, cases with nuclear expression of p53 revealed significantly higher levels of MDR1 mRNA expression, compared to those with negative immunoreaction for p53 (p=0.0328). Our results suggest that MDR1/P-gp expression may have an important role to play in tumor progression in the cases of soft tissue sarcoma, and p53 may be one of the active regulators of the MDR1 transcript. In addition, the high levels of both MDR1 and MRP3 mRNA expression in MPNST may help to explain the poor response of this tumor to anticancer-drugs.
...
PMID:ATP-binding cassette superfamily transporter gene expression in human soft tissue sarcomas. 1560 99

Treatment of HIV-1-infected patients with anti-retroviral agents is not always successful due to the emergence of resistant HIV-1 mutants with reduced susceptibility to the agents. However, factors other than viral mutation may also contribute to treatment failure. It has been demonstrated that the ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp/ABCB1) is a key determinant of oral bioavailability of HIV-1 protease inhibitors and their penetration of the central nervous system. More recently, we have found that the expression of breast cancer resistance protein (BCRP/ABCG2) in a CD4+ T-cell line confers cellular resistance to nucleoside reverse transcriptase inhibitors (NRTIs). The anti-HIV-1 activity of the NRTI zidovudine (AZT) was significantly diminished through the reduction of its metabolite levels in MT-4 cells which express high levels of BCRP. Moreover, the BCRP-specific inhibitor fumitremorgin C could completely restore the cytotoxicity of AZT and intracellular levels of its metabolites in BCRP-expressing cells. Thus, BCRP is considered to be a cellular factor that modulates the anti-HIV-1 activity of NRTIs.
...
PMID:The role of breast cancer resistance protein (BCRP/ABCG2) in cellular resistance to HIV-1 nucleoside reverse transcriptase inhibitors. 1613 May 19


1 2 3 Next >>

---