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

Important aspects of successful adenovirus gene transfer include the amount and persistence of gene expression, the ability to readminister virus and the localization of virus-directed gene expression to target organs. Our objective in this study was to use a single recombinant adenovirus bearing a quantifiable reporter gene [chloramphenicol acetyltransferase (CAT)] to establish the parameters which define the limits of adenovirus gene expression in a rat model. First, we determined how the route of virus administration affected the amount, duration and distribution of expression in different tissues and in rats of different developmental stages. All routes resulted in infection of all tissues tested. Surprisingly, the most efficient and widespread gene transfer was achieved by intracardiac muscle injection. The high levels of CAT protein that can be produced in a liver (< or = 1.7 mg) or a heart (< or = 196 micrograms) 5 days after infection suggest that the amount of gene product will not be a limitation in the use of adenovirus. Following peak activity at 5 days after infection, a gradual decline of CAT expression was observed in all tissues assayed; by 80 days neither CAT activity nor adenovirus DNA were detectable. In addition, adults could not be boosted by a second administration of virus, presumably due to the presence of high levels of neutralizing antibodies. The limited persistence of gene expression could be circumvented when virus was injected into neonates. Blocking T lymphocyte expansion by cyclosporine enhanced the persistence of CAT gene product over a 25-day period in heart and lung but not in liver compared with control animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The impact of developmental stage, route of administration and the immune system on adenovirus-mediated gene transfer. 758 5

CD3 mAb and HIV-1 Tat protein co-immobilized on plastic were able to induce a strong proliferation of resting human CD4 T cells, cultured in a serum-free chemically defined medium. Blocking studies performed with heparin or peptides containing the RGD sequence demonstrated that the heparin-binding basic domain of Tat plays a predominant role in CD4+ T cell activation. Moreover, the enhanced proliferative response of CD4+ T cells to immobilized Tat appeared to be mediated by alpha 5, beta 1, and alpha v subunits of surface integrin receptors. In contrast, soluble Tat showed a dose-dependent inhibitory activity on the proliferative response of resting CD4+ T cells stimulated by CD3 mAb co-immobilized with Tat or fibronectin, but not with CD28 mAb. In transient transfection assays performed with an HIV-1 long terminal repeat (LTR)-chloramphenicol acetyltransferase (CAT) plasmid CD3 mAb co-immobilized with Tat or fibronectin or CD28 mAb significantly stimulated CAT activity over the background. On the other hand, while immobilized Tat alone had no effects on LTR transactivation, soluble Tat was able to transactivate LTR-CAT in a dose-dependent manner. When CD4+ T cells activated by CD3 mAb co-immobilized with Tat were recovered, cultured for 7 days with 25 U/ml recombinant IL-2, and given an additional activation signal by recross-linking CD3 mAb, a marked increase of apoptosis was observed with respect to cells not subjected to CD3 mAb recross-linking. While co-immobilized Tat plus CD3 mAb did not show any significant effect on activation-induced cell death, high concentrations of soluble Tat synergized with immobilized CD3 mAb in the induction of apoptosis.
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PMID:Pleiotropic effects of immobilized versus soluble recombinant HIV-1 Tat protein on CD3-mediated activation, induction of apoptosis, and HIV-1 long terminal repeat transactivation in purified CD4+ T lymphocytes. 875 49

Adhesion to extracellular matrices is known to modulate leukocyte activation, although the mechanisms are not fully understood. Mononuclear phagocytes are exposed to fibrinous provisional matrix throughout migration into inflammatory foci, so this study was undertaken to determine whether fibrinogen triggers activation of NF-kappa B transcription factors. U937 cells differentiated with PMA in nonadherent culture were shown to express two fibrinogen-binding integrins, predominately CD11b/CD18, and to a lesser extent, CD11c/CD18. Cells stimulated with fibrinogen (10-100 microg/ml)/Mn2+ (50 microM) for 2 h were examined by electrophoretic mobility shift assay. NF-kappa B activation, minimal in unstimulated cells, was substantially up-regulated by fibrinogen. Fibrinogen also caused activation of AP-1, but not SP1 or cAMP response element-binding protein (CREB) factors. Blocking mAbs against CD18 and CD11b abrogated fibrinogen-induced NF-kappa B activation. To determine the effects on transcriptional regulation, U937 cells were transfected with a plasmid containing the HIV-1 enhancer (bearing two NF-kappa B sites) coupled to a chloramphenicol acetyltransferase (CAT) reporter. Cells were subsequently stimulated with 1) PMA for 24 h, inducing CAT activity by 2.6-fold, 2) fibrinogen/Mn2+ for 2 h, inducing CAT activity by 3.2-fold, or 3) costimulation with fibrinogen and PMA, inducing 5.7-fold the CAT activity induced by PMA alone. We conclude that contact with fibrinogen-derived proteins may contribute to mononuclear phagocyte activation by signaling through CD11b/CD18, resulting in selective activation of transcriptional regulatory factors, including NF-kappa B.
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PMID:Fibrinogen activates NF-kappa B transcription factors in mononuclear phagocytes. 968 12