Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

EBV infection of B cells induces the B cell activation Ag, CD23 (Fc epsilon RII). CD23 remains constitutively expressed at high levels in all EBV-immortalized B cells and likely plays an important role in the initiation and maintenance of immortalization by EBV. By utilizing an EBV-negative Burkitt's lymphoma line (BJAB) and EBV-positive sublines derived from it by in vitro infection, we have examined the molecular mechanisms involved in the regulation of CD23 by EBV. By nuclear runoff analysis, we have found that induction of CD23 is mediated by transcriptional activation that occurs in the presence of the transformation-competent B958 virus but not in the presence of the nontransforming P3HR-1 strain of EBV. To identify EBV-responsive transcriptional regulatory elements of CD23, we have performed reporter gene assays using plasmids containing fragments of the CD23 gene derived from its 5' terminus and adjacent flanking region transfected into EBV-positive and -negative BJAB lines. We have identified a 534-bp fragment of the gene which enhances transcription from a heterologous promoter (SV40) and reporter gene (chloramphenicol acetyltransferase) only in the presence of transformation-competent strains of EBV. Deletion of 144 bp of intron 1 from the 3' end of this fragment results in loss of EBV-responsive enhancer activity. The finding of an EBV-responsive enhancer element of CD23 is supported by mobility shift assays that demonstrated the formation of specific DNA-protein complexes between nuclear protein from transforming EBV-positive cells and the 144-bp intron sequence. These studies suggest that the transcriptional activation of CD23 by transforming strains of EBV involves regulatory elements that are located within the first intron of the gene.
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PMID:Transcriptional regulation of the human IgE receptor (Fc epsilon RII/CD23) by EBV. Identification of EBV-responsive regulatory elements in intron 1. 131 50

Transcription of the terminal protein (TP) gene of Epstein-Barr virus (EBV) in Burkitt's lymphoma cells, in EBV-negative Burkitt's lymphoma cells converted with transformation-defective (P3HR1) and transformation-competent (B95-8, AG876) EBV strains, and in EBV-immortalized cell lines was studied. A TP1 cDNA probe spanning the boundary between exons 1 and 2 and discriminating between TP1 and TP2 transcripts was used for S1 analysis. TP RNA expression varied widely in Burkitt's lymphoma cells. TP-specific transcripts were not detectable or only hardly detectable in Burkitt's lymphoma cells with the group I phenotype (CD10+ CD77+ CD21- CD23- CD30- CDw70-) as well as in P3HR1 virus-converted Burkitt's lymphoma lines. TP expression was high in Burkitt's lymphoma lines with the group II and group III phenotypes (CD21+ CD23+ CD30+ CDw70+), in B95-8 and AG876 virus-converted lines, and in EBV-immortalized cells. Detection of TP1 RNA correlated with EBNA2 expression. TP1 transcription was shown to be dependent on EBNA2 expression by stable transfection of an EBNA2 expression vector into P3HR1 virus-converted BL41 cells. EBNA2 is activating the TP1 as well as the TP2 promoter, as shown by the analysis of TP promoter-chloramphenicol acetyltransferase constructs transiently transfected into EBNA2-positive and EBNA2-negative Burkitt's lymphoma cells.
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PMID:Epstein-Barr virus nuclear antigen 2 activates transcription of the terminal protein gene. 184

Several lines of evidence are compatible with the hypothesis that Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) or leader protein (EBNA-LP) affects expression of the EBV latent infection membrane protein LMP1. We now demonstrate the following. (i) Acute transfection and expression of EBNA-2 under control of simian virus 40 or Moloney murine leukemia virus promoters resulted in increased LMP1 expression in P3HR-1-infected Burkitt's lymphoma cells and the P3HR-1 or Daudi cell line. (ii) Transfection and expression of EBNA-LP alone had no effect on LMP1 expression and did not act synergistically with EBNA-2 to affect LMP1 expression. (iii) LMP1 expression in Daudi and P3HR-1-infected cells was controlled at the mRNA level, and EBNA-2 expression in Daudi cells increased LMP1 mRNA. (iv) No other EBV genes were required for EBNA-2 transactivation of LMP1 since cotransfection of recombinant EBNA-2 expression vectors and genomic LMP1 DNA fragments enhanced LMP1 expression in the EBV-negative B-lymphoma cell lines BJAB, Louckes, and BL30. (v) An EBNA-2-responsive element was found within the -512 to +40 LMP1 DNA since this DNA linked to a chloramphenicol acetyltransferase reporter gene was transactivated by cotransfection with an EBNA-2 expression vector. (vi) The EBV type 2 EBNA-2 transactivated LMP1 as well as the EBV type 1 EBNA-2. (vii) Two deletions within the EBNA-2 gene which rendered EBV transformation incompetent did not transactivate LMP1, whereas a transformation-competent EBNA-2 deletion mutant did transactivate LMP1. LMP1 is a potent effector of B-lymphocyte activation and can act synergistically with EBNA-2 to induce cellular CD23 gene expression. Thus, EBNA-2 transactivation of LMP1 amplifies the biological impact of EBNA-2 and underscores its central role in EBV-induced growth transformation.
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PMID:Epstein-Barr virus nuclear antigen 2 transactivates latent membrane protein LMP1. 235 28