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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Loss of heterozygosity (LOH) at chromosome 10q23-q25 is frequent in small cell lung cancer (SCLC), indicating the presence of putative tumor suppressor genes. PTEN/ MMAC1, a newly cloned candidate tumor suppressor gene at 10q23, was mutated in multiple human cancers. We investigated whether mutations of PTEN/MMAC1 play an important role in SCLC tumorigenesis. We examined 16 SCLC cell lines for PTEN/MMAC1 mRNA expression by reverse-transcriptase polymerase chain reaction (RT-PCR) and potential mutations by sequencing analysis of the PTEN/MMAC1 coding region. No mutation was observed in PTEN/MMAC1 cDNAs in 15 cell lines expressing PTEN/MMAC1. One SCLC cell line, DMS79, did not have detectable PTEN/ MMAC1 expression. Importantly, we identified a novel homologue of PTEN/MMAC1, termed PTH2, localized to chromosome 9p21-q13 and containing only ten amino acid substitutions compared with the PTEN/MMAC1 coding region. However, because the putative initiation codon for PTEN/MMAC1 gene was changed to arginine in PTH2, the translational initiation site of PTH2 is very likely to differ from that of the PTEN/MMAC1. PTH2 was expressed in two normal lung tissues and two normal colon tissues, but in only four of 16 SCLC cell lines. A missense mutation in PTH2 was identified in a SCLC cell line that did not express PTEN/MMAC1 mRNA. Our data suggest that inactivation of PTEN/ MMAC1 is a rare event in SCLC tumorigenesis. However, the PTEN/MMAC1 homologue PTH2 may play a role in SCLC tumorigenesis.
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PMID:Alterations of PTEN/MMAC1, a candidate tumor suppressor gene, and its homologue, PTH2, in small cell lung cancer cell lines. 946 47

A role for human papilloma virus (HPV) infection in the pathogenesis of head and neck neoplasms has gained support in recent years. Expression of two early-region HPV genes, E6 and E7, is widely accepted as essential for viral-induced carcinomas of the genital tract. These oncoproteins interact with the products of the cellular tumor suppressor genes, p53 and retinoblastoma, and inactivate them. Examining E6/E7 transforming gene expression is an important step toward elucidating the pathogenesis of HPV in head and neck neoplasms. We introduce nasal inverted papilloma (IP) as a novel system for evaluating viral genomic expression and transforming gene regulation of tumorigenesis by virtue of its association to HPV infection and potential for malignant progression. We describe here a reverse transcriptase-polymerase chain reaction approach for the detection of HPV E6/E7-specific transcripts in RNA extracted from IR. A primer pair flanking previously mapped HPV 6 E6/E7 splice donor/acceptor sites was used to direct amplification of cDNA. Reverse transcriptase-polymerase chain reaction experiments generated products representing the 1.2 Kb E1E4 splice transcript and a smaller unclassified fragment in IP from two patients. These results provide evidence for HPV 6 E6/E7 expression in IP with the potential to encode transforming proteins.
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PMID:The HPV 6 E6/E7 transforming genes are expressed in inverted papilloma. 952 9

The cellular role of the PML-containing nuclear bodies also known as ND10 or PODs remains elusive despite links to oncogenesis and viral replication. Although a potential role in transcription has been considered, direct evidence has been lacking. By developing a novel in vivo nucleic acid labeling approach, we demonstrate the existence of nascent RNA polymerase II transcripts within this nuclear body. In addition, PML and the transactivation cofactor, CREB binding protein (CBP), colocalize within the nucleus. Furthermore, we show that CBP in contrast to PML is distributed throughout the internal core of the structure. Collectively, these findings support a role for this nuclear body in transcriptional regulation.
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PMID:Localization of nascent RNA and CREB binding protein with the PML-containing nuclear body. 956 Feb 16

The hepatitis B virus (HBV) X protein is essential for viral infectivity, and evidence indicates that it is a strong contributor to HBV-mediated oncogenesis. X has been shown to transactivate a wide variety of RNA polymerase (Pol) II-dependent, as well as RNA Pol III-dependent, promoters. In this study, we have investigated the possibility that X modulates RNA Pol I-dependent rRNA transcription. In both human hepatoma Huh7 and Drosophila Schneider S2 cell lines, X expression stimulated rRNA promoter activity. Extracts prepared from X-expressing cells stably transfected with an X gene also exhibited an increased ability to transcribe the rRNA promoter. The mechanism for X transactivation was examined by determining whether this regulatory event was dependent on Ras activation and increased TATA-binding protein (TBP) levels. Our previous studies have demonstrated that X, and the activation of Ras, produces an increase in the cellular levels of TBP (H.-D. Wang, A. Trivedi, and D. L. Johnson, Mol. Cell. Biol. 17:6838-6846, 1997). Expression of a dominant negative form of Ras blocked the X-mediated induction of the rRNA promoters, whereas expression of a constitutively activated form of Ras mimicked the enhancing effect of X on rRNA promoter activity. When TBP was overexpressed in either Huh7 or S2 cells, a dose-dependent increase in rRNA promoter activity was observed. To analyze whether the increase in TBP was modulating rRNA promoter activity indirectly, by increasing activity of RNA Pol II-dependent promoters, a Drosophila TBP cDNA was constructed with a mutation that eliminated its ability to stimulate RNA Pol II-dependent promoters. Transient expression of wild-type TBP in S2 cells increased the activities of specific RNA Pol I- and Pol II-dependent promoters. Expression of the mutant TBP protein failed to enhance the activity of the RNA Pol II-dependent promoters, yet the protein completely retained its ability to stimulate the rRNA promoter. Furthermore, the addition of recombinant TBP to S2 extracts stimulated rRNA promoter activity in vitro. Together, these results demonstrate that the HBV X protein up-regulates RNA Pol I-dependent promoters via a Ras-activated pathway in two distinct cell lines. The enhanced promoter activity can, at least in part, be attributed to the X- and Ras-mediated increase in cellular TBP, a limiting transcription component.
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PMID:Regulation of RNA polymerase I-dependent promoters by the hepatitis B virus X protein via activated Ras and TATA-binding protein. 981 95

Histone acetylation and phosphorylation destablizes nucleosome and chromatin structure. Relaxation of the chromatin fiber facilitates transcription. Coactivator complexes with histone acetyltransferase activity are recruited by transcription factors bound to enhancers or promoters. The recruited histone acetyltransferases may acetylate histone or nonhistone chromosomal proteins, resulting in the relaxation of chromatin structure. Alternatively, repressors recruit corepressor complexes with histone deacetylase activity, leading to condensation of chromatin. This review highlights the recent advances made in our understanding of the roles of histone acetyltransferases, histone deacetylases, histone kinases, and protein phosphatases in transcriptional activation and repression. Exciting reports revealing mechanistic connections between histone modifying activities and the RNA polymerase II machinery, the coupling of histone deacetylation and DNA methylation, the possible involvement of histone deacetylases in the organization of nuclear DNA, and the role of chromatin modulators in oncogenesis are discussed.
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PMID:Regulation and regulatory parameters of histone modifications. 989 72

Epstein-Barr virus (EBV)-associated smooth muscle tumors following solid organ transplantation are extremely rare, with only 12 cases reported in the literature thus far. The exact pathogenetic role of EBV infection in the oncogenesis of these soft tissue tumors in immunodeficient patients and the biologic behavior of such tumors is still unclear. We report a 26-year-old man in whom multiple smooth muscle tumors developed 36 to 51 months after heart transplantation. All tumors, two synchronous liver nodules, two subsequently occurring paravertebral tumors, and a single tumor in a vein at the left ankle were surgically resected. The tumor tissue was processed for routine histology and immunohistochemical (IHC) stains. Additionally, competitive polymerase-chain-reaction (PCR), reverse-transcriptase PCR (RT-PCR), as well as in situ hybridization (ISH) were used for EBV particle quantification and gene transcription analysis. The histologic features and immunohistochemical profiles were consistent with leiomyosarcoma in all tumor nodules. EBV infection was detected in >95% of tumor cell nuclei by EBER 1/2 ISH. Competitive PCR revealed 3105 EBV particles per milligram of tumor tissue. The EBV gene expression pattern analyzed by RT-PCR and IHC corresponded to the latency type III with specific expression of EBNA1, EBNA2, LMP1, and LMP2A genes. Under continuous antiviral therapy (famcyclovir) the patient currently shows no evidence of disease. Our data indicate that EBV infection plays a causal role in the development of smooth muscle tumors following organ transplantation. A latency type III, identical to EBV-associated posttransplant lymphoproliferative disorders, was identified and suggests a common pathogenetic mechanism in the development of these histogenetically distinct neoplasms. The fact that the patient currently shows no evidence of disease may be the result of the continuous administration of antiviral therapy because the soft tissue recurrences of the leiomyosarcoma occurred while the patient was not receiving antiviral prophylaxis.
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PMID:Epstein-Barr virus-associated multicentric leiomyosarcoma in an adult patient after heart transplantation: case report and review of the literature. 1075 11

The nucleosome and chromatin fiber provide the common structural framework for transcriptional control in eukaryotes. The folding of DNA within these structures can both promote and impede transcription dependent on structural context. Importantly, neither the nucleosome nor the chromatin fiber is a static structure. Histone dissociation, histone modification, nucleosome mobility, and assorted allosteric transitions contribute to transcriptional control. Chromatin remodeling is associated with gene activation and repression. Energy-dependent processes mediate the assembly of both activating and repressive proteins into the nucleosomal infrastructure. Recent progress allows the structural consequences of these processes to be visualized at the chromosomal level. DNA and RNA polymerase, SWI/SNF complexes, histone deacetylases, and acetyltransferases are targeted by gene-specific regulators to mediate these structural transitions. The mistargeting of these enzymes contributes to human developmental abnormalities and tumorigenesis. These observations illuminate the roles of chromatin and chromosomal structural biology in human disease.
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PMID:Review: chromatin structural features and targets that regulate transcription. 1080 63

The beta-1,6-N-acetylglucosaminyltransferase (beta1,6GnT) gene family encodes enzymes playing crucial roles in glycan synthesis. Important changes in beta1,6GnT expression are observed during development, oncogenesis, and immunodeficiency. The most characterized beta1,6GnTs in this gene family are the human (h) C2GnT-L and h-IGnT, which have core 2 [Galbeta1-->3(GlcNAcbeta1-->6)GalNAc] and I branching [GlcNAcbeta1-->3(GlcNAcbeta1-->6)Gal] activities, respectively. Recently, h-C2GnT-M was shown to be unique in forming core 2, core 4 [GlcNAcbeta1-->3(GlcNAcbeta1-->6)GalNAc], and I structures. To date, the beta1,6GnT gene family has been characterized only in mammals. Here, we describe that bovine herpesvirus type 4 (BHV-4) encodes a beta1,6GnT expressed during viral replication and exhibiting all of the core 2, core 4, and I branching activities. Sequencing of the BHV-4 genome revealed an ORF, hereafter called BORFF3-4, encoding a protein (pBORFF3-4) exhibiting 81.1%, 50.7%, and 36.6% amino acid identity with h-C2GnT-M, h-C2GnT-L, and h-IGnT, respectively. Reverse transcriptase-PCR analysis revealed that BORFF3-4 is expressed during BHV-4 replication. Expression of BORFF3-4 in Chinese hamster ovary cells directed the expression of core 2 branched oligosaccharides and I antigenic structures on the cell surface. Moreover, a soluble form of pBORFF3-4 had core 4 branching activity in addition to core 2 and I branching activities. Finally, infection of a C2GnT-negative cell line with BHV-4 induced expression of core 2 branched oligosaccharides. This study extends the beta1,6GnT gene family to a viral gene and provides a model to study the biological functions of a beta1,6GnT in the context of viral infection.
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PMID:A multipotential beta -1,6-N-acetylglucosaminyl-transferase is encoded by bovine herpesvirus type 4. 1081 84

cDNA microarray technology allows the "profiling" of gene expression patterns for virtually any cellular material. In this study, we applied cDNA microarray technology to profile changes in gene expression associated with human prostate tumorigenesis. RNA prepared from normal and malignant prostate tissue was examined for the expression levels of 588 human genes. Four different methods for data normalization were utilized. Of these, normalization to ACTB expression proved to be the most rigorous technique with the least probability of producing spurious results. After normalization to ACTB expression, 15 of 588 (2.6%) genes examined by array analysis were differentially expressed by a factory of 2x or more in malignant compared to normal prostate tissues. The expression patterns for 8 of 15 genes have been reported previously in prostate tissues (TGFbeta3, TGFBR3, IGFII, IGFBP2, VEGF, FGF7, ERBB3, MYC), but those of seven genes are reported here for the first time (MLH1, CYP1B1, RFC4, EPHB3, MGST1, BTEB2, MLP). These genes describe at least four metabolic and signaling pathways likely disrupted in human prostate tumorigenesis. Reverse transcriptase polymerase chain reaction (RT-PCR) and Northern blot analyses quantitated with reference to ACTB expression levels verified the trends in gene expression levels observed by array analysis for 14/15 and 8/8 genes, respectively. However, RT-PCR and Northern blot analyses accurately verified the "fold" differences in expression levels for only 6/15 (40%) and 7/8 (88%) of genes examined, respectively, demonstrating the need to better validate quantitative differences in gene expression revealed by array-based techniques.
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PMID:Profiling and verification of gene expression patterns in normal and malignant human prostate tissues by cDNA microarray analysis. 1132 15

Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic growth factor produced principally by cells of mesenchymal origin. HGF/SF is an important mitogen, morphogen, and motogen and plays an important role in wound healing, tumorigenesis and particularly fetal development. Oral mucosal fibroblasts exhibit a fetal phenotype, including an increased extracellular matrix reorganizational ability, cellular migration and experimental wound repopulation in comparison to skin fibroblasts. In this study the expression, production, and bioactivity of HGF/SF by oral mucosal and skin fibroblasts was investigated. Although both oral mucosal and skin fibroblasts expressed HGF/SF, the oral mucosal fibroblasts produced significantly increased amounts of total HGF/SF (p < 0.01) as measured by enzyme-linked immunosorbent assay and bioactive HGF/SF as measured by cell scatter and cell-dissociation techniques (p < 0.01). The possible effect of increased HGF/SF in production mediating the previously described preferential responses of oral mucosal fibroblasts was studied in vitro. Reverse transcriptase-polymerase chain reaction-Western blotting and immunocytochemistry methods all showed that both oral mucosal and skin fibroblasts expressed and produced the c-Met receptor. Recombinant HGF (20-40 ng/mL) however, failed to affect fibroblast repopulation of monolayer wounds or cellular proliferation. In contrast, recombinant HGF significantly increased ECV304 wound repopulation. These studies provide direct evidence of another mechanism by which site-specific variations in fibroblast phenotype may contribute in a paracrine fashion to the rapid reepithelialization and revascularization of oral wounds.
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PMID:Phenotypic variation in the production of bioactive hepatocyte growth factor/scatter factor by oral mucosal and skin fibroblasts. 1135 Jun 38


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