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)

Gene rearrangements activating the RET proto-oncogene are frequently associated with human thyroid carcinomas belonging to the papillary subtype. These arrangements cause the fusion of the tyrosine-kinase domain of RET to the 5'-terminal region of different genes creating the RET/PTC chimeric oncogenes. Here we report the generation of transgenic mice lines expressing the RET/PTC1 oncogene under the control of the thyroid-specific rat thyroglobulin promoter. RET/PTC1-transgenic mice developed thyroid tumors displaying the histological aspect of papillary carcinomas. These tumors were slowly progressive and did not cause premature death of the animals. Two additional mice developed areas of thyroid hyperplasia. Immunohistochemical and reverse-transcriptase polymerase chain reaction analyses confirmed the thyroid-specific expression of the transgene. Given the frequency of activating rearrangements of RET in human papillary thyroid carcinomas we conclude that this animal system could be a good model for studying the neoplastic progression of thyroid carcinomas.
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PMID:Development of thyroid papillary carcinomas secondary to tissue-specific expression of the RET/PTC1 oncogene in transgenic mice. 862 3

An intrinsic property of class I gene transcription by RNA polymerase I (Pol I) is the species specificity of the initiation reaction. Previous studies have demonstrated that species-specific rDNA promoter recognition is brought about by a TBP-TAF complex, termed TIF-IB in mouse and SL1 in man. We have compared the ability of affinity-purified TIF-IB and SL1 to direct transcription from the homologous rDNA template both in a reconstituted transcription system and in nuclear extracts prepared from mouse and human cells. We show that Pol I from both species and the individual transcription factors, with the exception of TIF-IB/SL1, are functionally interchangeable in the reconstituted transcription system containing purified proteins. In nuclear extracts, however, species-specific differences are obvious. Whereas SL1 reprograms a heterologous mouse extract to recognize the human promoter, TIF-IB fails to reprogram a human extract unless it is complemented with mouse Pol I. Crude human, but not mouse, Pol I exhibits species-specific differences that disappear after purification. We propose that in extracts and less purified fractions human Pol I exists as 'holoenzyme' containing associated protein(s) that prevent assembly of TIF-IB-directed initiation complexes at the murine rDNA promoter.
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PMID:Species specificity of ribosomal gene transcription: a factor associated with human RNA polymerase I prevents transcription of mouse rDNA. 863 44

An unusual property of ribosomal gene transcription is its marked species specificity. This results from distinct promoter-recognition properties of the RNA polymerase I transcription apparatus. The purification and functional characterization of TIF-IB/SL1, a promoter-recognition factor containing the TATA-binding protein, as well as the recent cloning of cDNAs encoding the three subunits (TAF(I)s) of the respective human and mouse factor, will facilitate the molecular analysis of the mechanisms underlying species-specific rDNA transcription and reveal how the basal transcriptional machinery has evolved.
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PMID:Species specificity of transcription by RNA polymerase I. 866 54

Reverse transcriptase-polymerase chain reactions using foetal brain RNA with reverse and forward primers of the first, second and third NTRK4 region allowed us to obtain three amplified NTRK4 fragments. The specificity of amplified fragments was checked by digestion with restriction endonucleases AvrII, HindIII and PspII for the first, second and third regions, respectively. Each restriction site was specific for each amplified fragment. The fragment of the NTRK4 first region was also sequenced and the sequence determined was identical to the human NTRK4 sequence. The three amplified fragments were cloned in pBS. For the Southern technique, plasmid pBS-NTRK4a (with an insert of 1052 bp) detected a human 9-kb HindIII sequence which was localised unambiguously on chromosome 6. For fluorescence in situ hybridisation, the three plasmids, pBS-NTRK4a, pBS-NTRK4b (insert 924 bp) and pBS-NTRK4c (insert 1114 bp) were pooled and used as a probe. This NTRK4 probe was localised on 6p21. Of 50 metaphases analysed, 49 contained twin spot signals on both sister chromatids.
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PMID:Assignment of the NTRK4 (trkE) gene to chromosome 6p21. 868 98

Transcription factor IIH (TFIIH) is a multisubunit protein complex essential for both the initiation of RNA polymerase class II (pol II)-catalyzed transcription and nucleotide excision repair of DNA. Recent studies have shown that TFIIH copurifies with the cyclin-dependent kinase (cdk)-activating kinase complex (CAK) that includes cdk7, cyclin H, and p36/MAT1. Here we report the isolation of two TFIIH-related complexes: TFIIH* and ERCC2/CAK. TFIIH* consists of a subset of the TFIIH complex proteins including ERCC3 (XPB), p62, p44, p41, and p34 but is devoid of detectable levels of ERCC2 (XPD) and CAK. ERCC2/CAK was isolated as a complex that exhibits CAK activity that cosediments with the three CAK components (cdk7, cyclin H, and p36/MAT1) as well as the ERCC2 (XPD) protein. TFIIH* can support pol II-catalyzed transcription in vitro with lower efficiency compared with TFIIH. This TFIIH*-dependent transcription reaction was stimulated by ERCC2/CAK. The ERCC2/CAK and TFIIH* complexes are each active in DNA repair as shown by their ability to complement extracts prepared from ERCC2 (XPD)- and ERCC3 (XPB)-deficient cells, respectively, in supporting the excision of DNA containing a cholesterol lesion. These data suggest that TFIIH* and ERCC2/CAK interact to form the TFIIH holoenzyme capable of efficiently assembling the pol II transcription initiation complex and directly participating in excision repair reactions.
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PMID:Isolation and characterization of two human transcription factor IIH (TFIIH)-related complexes: ERCC2/CAK and TFIIH. 869 41

Transcription factor IIH (TFIIH) is a multisubunit complex required for transcription and for DNA nucleotide excision repair. TFIIH possesses three enzymatic activities: (i) an ATP-dependent DNA helicase, (ii) a DNA-dependent ATPase, and (iii) a kinase with specificity for the carboxyl-terminal domain of RNA polymerase II. The kinase activity was recently identified as the cdk (cyclin-dependent kinase) activating kinase, CAK, composed of cdk7, cyclin H, and MAT-1. Here we report the isolation and characterization of three distinct CAK-containing complexes from HeLa nuclear extracts: CAK, a novel CAK-ERCC2 complex, and TFIIH. CAK-ERCC2 can efficiently associate with core-TFIIH to reconstitute holo-TFIIH transcription activity. We present evidence proposing a critical role for ERCC2 in mediating the association of CAK with core TFIIH subunits.
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PMID:Human cyclin-dependent kinase-activating kinase exists in three distinct complexes. 869 42

The breakpoints of the translocation t(2;5)(p23;q35) associated with Ki-1-positive anaplastic large cell lymphoma (Ki-1 ALCL) have recently been cloned. They involve a novel tyrosine kinase gene, ALK, at 2p23 and the nucleophosmin gene, NPM, at 5q35. Reverse transcriptase-polymerase chain reaction (RT-PCR) with NPM and ALK primers detects a consistent fusion product in Ki-1 ALCL cases that have the translocation. In the course of a survey of 15 cases of Ki-1 ALCL, we identified a single case with a slightly smaller NPM-ALK RT-PCR product, among 12 cases positive for this fusion RNA. Sequencing of this novel NPM-ALK RT-PCR product showed an in-frame junction of NPM to ALK, 30 bases distal to the usual ALK junction site, but at the usual NPM Junction site. The predicted chimeric protein in this case is thus shorter by 10 amino acids, but the putative ALK catalytic domain remains intact. PCR with ALK primers bracketing the novel fusion point, performed on either cDNA or genomic DNA, yielded the same product, confirming that this novel ALK fusion point was located within an exon. Hybridization analysis of the genomic junction fragment isolated by long-range DNA PCR suggested that the ALK genomic breakpoint was also exonic. Cloning and sequencing of the genomic breakpoint confirmed that the break occurred within the 5' portion of the ALK exon participating in the fusion junction, 28 bases 3' to the normal ALK exon boundary, resulting in the use of a cryptic splice acceptor site two bases distal to the breakpoint. This case demonstrates that, in translocations resulting in chimeric transcripts, genomic breakpoints may rarely lie within an exon, provided that the reading frame is maintained and no domains presumed critical to tumorigenesis are deleted.
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PMID:Molecular variant of the NPM-ALK rearrangement of Ki-1 lymphoma involving a cryptic ALK splice site. 872 82

Biologic responses to peptide calciotropic hormones, such as parathyroid hormone (PTH) and calcitonin, exhibit desensitization. As with most hormones, however, the mechanisms of desensitization are not completely understood. For the beta 2-adrenergic receptor (beta 2AR) system, which is coupled to adenylyl cyclase via the stimulatory guanine nucleotide-binding regulatory (G5) protein, homologous desensitization is mediated in part by a receptor-specific kinase (beta ARK) and a soluble cofactor (beta-arrestin). Recently, this system has been reported to be involved in rapid homologous desensitization of the PTH/parathyroid hormone receptor protein (PTHrP) receptor. We have identified the presence of this system in bone using reverse-transcriptase PCR. Nucleotide sequence of PCR fragments from ROS 17/2.8 cells revealed 100% identity with rat brain beta ARK1 and beta-arrestin 1 sequences. Northern analyses with RNA from ROS 17/2.8, UMR 106-H5 cells, and primary cultures of nontransformed neonatal rat calvariae demonstrated two mRNA species of 4 and 2.6 kilobases (kb) for beta ARK and 7.5 kb for beta-arrestin, comparable to those found in bovine brain. beta ARK-like activity was demonstrated in cytosolic extracts of the UMR 106-H5 cells by assessing phosphorylation of the retinal photoreceptor, rhodopsin, by the extracts. Phosphorylation was enhanced with light-activated rhodopsin and by bovine brain G beta gamma subunits; heparin inhibited phosphorylation. These findings are characteristic of beta ARK. Expression of beta-arrestin in the UMR 106-H5 cells was confirmed by immunoblot. Thus, osteoblastic cells express proteins, beta ARK, and beta-arrestin, which may regulate desensitization of calciotropic hormone receptors.
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PMID:Beta-adrenergic receptor kinase-like activity and beta-arrestin are expressed in osteoblastic cells. 872 79

Neisseria gonorrhoeae WS1 is a spontaneous pyocin (a bacteriocin produced by Pseudomonas aeruginosa)-resistant mutant of N. gonorrhoeae FA19 that produces a truncated lipooligosaccharide (LOS) and is non-transformable. The LOS-specific mutation in WS1 was moved into a transformable background by transforming FA19 with chromosomal DNA from WS1 (generating strain JWS-1). A clone (pJCL2) capable of restoring JWS-1 to wild-type LOS expression, as detected by its acquisition of reactivity with monoclonal antibodies and by its complemented sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile, was isolated. Sequential unidirectional deletion and DNA sequence analysis of pJCL2 identified an open reading frame, designated lsi-7, that could complement the defect in JWS-1. Homology searches against various databases indicated that lsi-7 bad homology with several Escherichia coli genes involved in the phosphorylation of sugars. lsi-7 is adjacent to the lsi-6 gene, another gene involved in LOS biosynthesis. Complementation studies using Salmonella typhimurium lipopolysaccharide mutants showed lsi-6 and lsi-7 to be gonococcal homologs of S. typhimurium rfaD and rfaE, respectively. Reverse transcriptase PCR analysis demonstrated that lsi-6 and lsi-7 are part of the same transcriptional unit.
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PMID:Cloning, complementation, and characterization of an rfaE homolog from Neisseria gonorrhoeae. 875 86

The breakpoints of the translocation t(2;5)(p23;q35) associated with Ki-1-positive anaplastic large-cell lymphoma (Ki-1 ALCL) involve a novel tyrosine kinase gene, ALK, at 2p23 and the nucleophosmin gene, NPM, at 5q35. Reverse transcriptase-polymerase chain reaction (RT-PCR) using NPM and ALK primers detects a consistent fusion product in Ki-1 ALCL cases with the translocation, resulting from genomic breakpoints within the same respective introns of NPM and ALK. To examine the feasibility of long-range DNA PCR with the same exonic NPM and ALK primers for the detection of the genomic NPM-ALK rearrangement, we examined 20 cases of Ki-1 ALCL previously characterized by NPM-ALK RT-PCR. Ten cases were positive for the NPM-ALK fusion RNA and 10 were negative. We first confirmed that both the NPM and ALK normal introns are relatively short, approximately 1 and 2 kb, respectively, suggesting that the largest possible size for the chimeric NPM-ALK intron would be about 3 kb. All 10 cases positive by RT-PCR were also positive by long-range DNA PCR. The DNA PCR products ranged, as expected, from the sizes of the normal introns, between 0.5 and 2.5 kb. All 10 RT-PCR-negative cases were also negative by long-range DNA PCR, and control templates for RT-PCR and long-range DNA PCR were successfully amplified. Thus, we have shown that the introns involved by the NPM-ALK rearrangement seen in some Ki-1 lymphomas are relatively short, making the genomic rearrangement amenable to reliable detection by long-range DNA PCR. Furthermore, the variability observed in the sizes of chimeric introns in evidence against clustering of the genomic breakpoints within these introns.
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PMID:Detection of the NPM-ALK genomic rearrangement of Ki-1 lymphoma and isolation of the involved NPM and ALK introns. 886 27


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