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)

DNA sequence polymorphism in the genes encoding HLA class II proteins accounts for allelic diversity in antigen recognition and presentation and, thus, in the role of these cell surface glycoproteins as determinants of the scope of the T-cell repertoire. In addition, sequence polymorphism in the promoter-proximal transcriptional regulatory regions of these genes has been described, particularly for the HLA-DQB1 locus, where these differences may contribute to variation in locus- and allele-specific expression. In this study, we measured the effect of such regulatory sequence polymorphism on the expression of endogenous alleles of DQB1 in heterozygous cells. Quantitative reverse transcriptase-mediated PCR analysis showed that expression of the DQB1*0301 allele responded more rapidly to gamma interferon induction than that of DQB1*0302. We have analyzed functional effects of a prominent allelic polymorphism that consists of a TG dinucleotide present between the W and X1 consensus elements in the DQB1*0302 allele but missing in the DQB1*0301 allele. The dominant effect of this polymorphism was to introduce a variation in the spacing between the W and X1 elements of these two alleles. A secondary compensatory effect was specific for the TG dinucleotide itself, which was essential for the binding of a nuclear protein complex to the *0302 regulatory region immediately 5' of the X1 element. Derivatives of the DQB1 5' regulatory region were used to drive expression of the chloramphenicol acetyltransferase gene in transient transfections of human B-lymphoblastoid and gamma interferon-treated melanoma cell lines, demonstrating that the additional spacing between the W and X1 elements caused by the presence of the TG dinucleotide in the *0302 allele resulted in reduced expression compared with that driven by the *0301 fragment; this difference overshadowed an up-regulating effect on expression which corresponded to the binding of the TG-dependent nuclear protein complex. The presence of this polymorphism in multiple HLA-DQB1 alleles and in several species suggests selection for two alternative transcriptional regulatory mechanisms influencing expression of alleles of the same HLA locus.
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PMID:Functional effects of a natural polymorphism in the transcriptional regulatory sequence of HLA-DQB1. 765 94

Previous studies have demonstrated the expression of GATA-1 (a DNA-binding nuclear protein) in erythrocytes, megakaryocytes, eosinophils, basophils, mast cells, early marrow progenitor cells and in mouse and human erythroid leukaemia cell lines. We studied 31 bone marrow specimens from patients with acute myeloid leukaemia (AML) for GATA-1 expression by reverse transcriptase/polymerase chain reaction (RT/PCR) analysis. GATA-1 expression was detected in all of the patients with erythroleukaemia, and in one of nine patients with megakaryoblastic leukaemia, but absent from 17 patients with French-American-British (FAB) M1-5 leukaemia. In AML, GATA-1 expression is indicative of differentiation to the erythroid and possibly megakaryocytic lineages, analogous to its expression in normal haemopoiesis.
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PMID:GATA-1 is expressed in acute erythroblastic leukaemia. 819 39

Detection of E1-E4 protein in human papillomavirus (HPV 11)-infected tissue is tightly linked to detection of L1 major capsid protein. The only L1-containing transcript identified in HPV 11-infected tissue is the bicistronic E1-E4-L1 mRNA, potentially encoding both the E1-E4 and the L1 proteins. It has not been established that these proteins can be expressed from the E1-E4-L1 transcript. The HPV 11 E1-E4-L1 sequence was cloned by reverse transcriptase polymerase chain reaction into the p1393 vector to produce recombinant baculoviruses. Immunoblots of recombinant baculovirus-infected Sf9 cell lysates demonstrated both the E1-E4 and the L1 proteins. An ELISA was performed on infected Sf9 cells using a monoclonal antibody specific for nondenatured L1, demonstrating that 10 ng of native L1 protein was present per microgram of total nuclear protein. Electron microscopic analysis revealed 50- to 60-nm icosahedral virus-like particles. In vitro transcription/translation was performed using pSPORT constructs containing the E1-E4-L1 sequence or, as controls, monocistronic pSPORT-E1-E4 or L1 constructs. The pSPORT-E1-E4-L1 construct produced the E1-E4 and L1 proteins at a ratio of 17:1. For E1-E4 protein, expression was greater from the pSPORT-E1-E4-L1 construct than from the monocistronic pSPORT-E1-E4 construct. In contrast, more L1 protein was expressed from pSPORT-L1 than from pSPORT-E1-E4-L1. A mutant E1-E4-L1 construct containing no E1-E4 start codon expressed L1 protein in amounts nearly equal to that expressed from the pSPORT-L1 construct. Addition of an antisense oligonucleotide directed at the E1-E4 start codon region to in vitro reactions using pSPORT-E1-E4-L1 was associated with inhibition of E1-E4 protein synthesis and increased translation of L1 protein.
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PMID:Virus-like particles and E1-E4 protein expressed from the human papillomavirus type 11 bicistronic E1-E4-L1 transcript. 880 86

Detection of E1AE4 protein in human papillomavirus (HPV 11)-infected tissue is tightly linked to detection of L1 major capsid protein. The only L1-containing transcript identified in HPV 11-infected tissue is the bicistronic E1AE4AL1 mRNA, potentially encoding both the E1AE4 and the L1 proteins. It has not been established that these proteins can be expressed from the E1AE4AL1 transcript. The HPV 11 E1AE4AL1 sequence was cloned by reverse transcriptase polymerase chain reaction into the p1393 vector to produce recombinant baculoviruses. Immunoblots of recombinant baculovirus-infected Sf9 cell lysates demonstrated both the E1AE4 and the L1 proteins. An ELISA was performed on infected Sf9 cells using a monoclonal antibody specific for nondenatured L1, demonstrating that 10 ng of native L1 protein was present per microgram of total nuclear protein. Electron microscopic analysis revealed 50- to 60-nm icosahedral virus-like particles. In vitro transcription/translation was performed using pSPORT constructs containing the E1AE4AL1 sequence or, as controls, monocistronic pSPORT-E1AE4 or L1 constructs. The pSPORT-E1AE4AL1 construct produced the E1AE4 and L1 proteins at a ratio of 17:1. For E1AE4 protein, expression was greater from the pSPORT-E1AE4AL1 construct than from the monocistronic pSPORT-E1AE4 construct. In contrast, more L1 protein was expressed from pSPORT-L1 than from pSPORT-E1AE4AL1. A mutant E1AE4AL1 construct containing no E1AE4 start codon expressed L1 protein in amounts nearly equal to that expressed from the pSPORT-L1 construct. Addition of an antisense oligonucleotide directed at the E1AE4 start codon region to in vitro reactions using pSPORT-E1AE4AL1 was associated with inhibition of E1AE4 protein synthesis and increased translation of L1 protein.
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PMID:Virus-like Particles and E1AE4 Protein Expressed from the Human Papillomavirus Type 11 Bicistronic E1AE4AL1 Transcript 881 33

The CREB-binding protein (CBP) is a large nuclear protein that regulates many signal transduction pathways and is involved in chromatin-mediated transcription. The translocation t(8;16)(p11;p13.3) consistently disrupts two genes: the CBP gene on chromosome band 16p13.3 and the MOZ gene on chromosome band 8p11. Although a fusion of these two genes as a result of the translocation is expected, attempts at detecting the fusion transcript by reverse transcriptase polymerase chain reaction (RT-PCR) have proven difficult; to date, only one in-frame CBP/MOZ fusion transcript has been reported. We therefore sought other reliable means of detecting CBP rearrangements. We applied fluorescence in situ hybridization (FISH) and Southern blot analyses to a series of AML patients with a t(8;16) and detected DNA rearrangements of both the CBP and the MOZ loci in all cases tested. All six cases examined for CBP rearrangements have breakpoints within a 13 kb breakpoint cluster region at the 5' end of the CBP gene. Additionally, we used a MOZ cDNA probe to construct a surrounding cosmid contig and detect DNA rearrangements in three t(8;16) cases, all of which display rearrangements within a 6 kb genomic fragment of the MOZ gene. We have thus developed a series of cosmid probes that consistently detect the disruption of the CBP gene in t(8;16) patients. These clones could potentially be used to screen other cancer-associated or congenital translocations involving chromosome band 16p13.3 as well.
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PMID:Detection of CBP rearrangements in acute myelogenous leukemia with t(8;16). 944 25

IFN-gamma production is dramatically reduced in T cells from mice bearing large mammary tumors. This inhibition of IFN-gamma gene expression occurs mostly in CD4+ T cells, as determined by ELISA and reverse transcriptase-PCR. The effects of known mammary tumor factors in normal T cells and its subsets were evaluated. Pretreatment with granulocyte-macrophage CSF resulted in increased IFN-gamma levels by T cells, while PGE2 pretreatment equally decreased the levels of this cytokine in CD4+ and CD8+ T cells from normal mice. Interestingly, phosphatidyl serine (PS) down-regulated the IFN-gamma production of CD4+, but not that of CD8+, T cells. Methylation analysis indicated that the CpG dinucleotide in SnaBI site of the IFN-gamma 5' promoter flank region was hypermethylated in CD4+, but not in CD8+, T cells of large tumor bearers and of normal mice pretreated with PS. Electrophoresis mobility shift assay using an oligonucleotide probe corresponding to the IFN-gamma promoter core region sequence showed a greatly reduced binding of a 90-kDa nuclear protein in CD4+ T cells from tumor bearers and in those from PS-pretreated normal mice. Since IL-2 production is not affected in either CD4+ or CD8+ T cells from tumor bearers, these studies indicate that IFN-gamma production can be regulated independently from that of other type 1 cytokines in vivo. Our data further suggest that PS is involved in IFN-gamma gene down-regulation during mammary tumorigenesis and contributes to the generalized immunosuppression associated with tumor growth.
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PMID:CD4+, but not CD8+, T cells from mammary tumor-bearing mice have a down-regulated production of IFN-gamma: role of phosphatidyl serine. 951 Jan 74

To investigate whether brown adipose tissue (BAT) expresses the inducible (HO-1) and the constitutive (HO-2) isoform of heme oxygenase, reverse transcriptase-polymerase chain reaction, Western blotting and immunohistochemistry were performed on interscapular BAT (IBAT) from rats acclimated at environmental temperature or exposed to cold. Both HO isoforms were detected in rat IBAT. They were immunolocalized in the cytoplasm and/or nuclei of brown adipocytes, in parenchymal capillaries, arteries and in some veins and nerves. Whereas cold exposure did not affect HO-2 expression, it significantly increased the expression of HO-1, both at mRNA (about 3-fold) and protein (about 2-fold) levels, reflecting the increased expression of HO-1 in the brown adipocytes and endothelial cells of parenchymal capillaries. Western blotting of cytosolic and nuclear protein extracts from cultured differentiated brown adipocytes showed that HO-1 and HO-2 are indeed localized in the cytosol and nuclei of brown adipocytes, and that noradrenaline stimulation significantly increased their amount in cytosol but not in the nuclear fraction.
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PMID:Expression and distribution of heme oxygenase-1 and -2 in rat brown adipose tissue: the modulatory role of the noradrenergic system. 1115 May 3

The telomerase enzyme is a reverse transcriptase capable of replacing the telomeric DNA sequences that are lost at each cell division. Telomerase activation permits extended cell proliferation beyond normal senescence checkpoints, and accordingly, telomerase activity has been detected in a wide range of malignant cells and tissues but is absent in terminally differentiated somatic cells. To date, the majority of cancer-related telomerase analyses have been performed on carcinomas that originate from epithelial cells, and few reports have included tumors originating from nonepithelial cells. In this study, we used the PCR-based telomeric repeat amplification protocol (TRAP) to assay telomerase activity in nuclear protein extracts obtained from a range of malignant and benign connective tissue lesions. In total, 62 histologically diagnosed specimens were analyzed including 37 sarcomas, 7 benign mesenchymal tumors, 12 normal tissue samples, and 6 carcinoma metastases obtained from bone. Thirty (81%) of the 37 primary sarcoma samples contained telomerase activity, and four of the six carcinoma metastases were also positive. Conversely, telomerase activity was detectable in only one of seven benign lesions and in none of the 12 normal connective tissue controls. Tumors of connective tissue origin can sometimes be difficult to categorize and to evaluate microscopically with regard to clinical management. As is the case in carcinomas, the presence of telomerase activity appears to be indicative of malignancy in mesenchymal tumor biopsy material and therefore may be useful as an adjunct to the pathologist in the assessment of borderline cases.
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PMID:Telomerase activity in soft-tissue and bone sarcomas. 1115 34

A diverse collection of Ty1-copia group retrotransposons has been characterized from the genome of Picea abies (Norway spruce) by degenerate PCR amplification of a region of the reverse transcriptase gene. The occurrence of these retrotransposable elements in the gymnosperms was investigated by Southern blot hybridization analysis. The distribution of the different retrotransposons across the gymnosperms varies greatly. All of the retrotransposon clones isolated are highly conserved within the Picea (spruce) genus, many are also present in Pinus (pine) and/or Abies (fir) genera, and some share strongly homologous sequences with one or more of cedar, larch, Sequoia, cypress, and Ginkgo. Further subclones of one of the most strongly conserved retrotransposon sequences, Tpa28, were obtained from Ginkgo and P. abies. Comparisons of individual sequence pairs between the two species show nucleotide cross-homologies of around 80%-85%, corresponding to nucleotide substitution rates similar to those of nuclear protein-coding genes. Analysis of Tpa28 consensus sequences reveals that strong purifying selection has acted on this retrotransposon in the lineages connecting Ginkgo and Picea. Collectively, these data suggest, first, that the evolution of the Ty1-copia retrotransposon group in the gymnosperms is dominated by germ line vertical transmission, with strong selection for reverse transcriptase sequence, and, second, that extinction of individual retrotransposon types has been comparatively rare in gymnosperm species lineages compared with angiosperms. If this very high level of sequence conservation is a general property of the retrotransposons, then their extreme sequence diversity implies that they are extremely ancient, and the major element lineages seen today may have arisen early in eukaryote evolution. The data are also consistent with horizontal transmission of particular retrotransposons between species, but such a mechanism is unnecessary to explain the results.
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PMID:The evolution of Ty1-copia group retrotransposons in gymnosperms. 1115 74

We characterize the cDNA and genomic structure of NSBP1, and demonstrate that it is a nuclear protein and the homologue of mouse Nsbp1, which is known to encode a nucleosomal binding and transcriptional activating protein related to the HMG-14/-17 chromosomal proteins. The encoded NSBP1 protein has 86% amino acid similarity to Nsbp1, including identity in nucleosomal binding domains of the HMG-14/-17 proteins. Our radiation hybrid data localize NSBP1 and Nsbp1 to homologous regions of chromosome X, with NSBP1 in Xq13.3 between DXS983 and DXS995 and Nsbp1 in the interval DXMit65 and DXMit39. Although Nsbp1 produces one mRNA transcript, NSBP1 produces three transcripts with alternate polyadenylated sites. The 3' untranslated region (UTR) of NSPB1 mRNA also contains several AU-rich elements (AREs), which are associated with rapid mRNA turnover. Northern analysis of NSBP1/Nsbp1 shows differences in transcript abundance among adult and fetal tissues, with predominant expression in liver, kidney, trabecular bone, and bone marrow stromal cells. However, a reverse transcriptase-PCR analysis shows nearly ubiquitous expression of the three NSBP1 transcripts in all tissues examined, although the abundance of each transcript was not quantified. NSBP1 is encoded by six exons and has exon-intron boundaries identical to the HMG-14/-17 genes. The last exon and the 3' UTR of NSBP1 contain retrotransposon sequences of HAL1, HERV-H, and L1MB7, suggesting that these retrotransposons were involved in the origin of NSPB1 from an ancestral-like HMG-14/-17 gene. The similarities among NSBP1, Nsbp1, and the HMG-14/-17 proteins suggest that NSBP1 may function as a nucleosomal binding and transcriptional activating element. Further, the AREs in the 3' UTR of NSPB1 suggest that alternate poly(A) site selection may mediate the mRNA stability of this gene.
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PMID:Characterization of a human gene encoding nucleosomal binding protein NSBP1. 1116 10


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