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)

Previous work has shown that the 68-kDa immediate-early protein of herpes simplex virus type 1 (HSV-1), also known as ICP22, is involved in the control of viral gene expression, although the precise mechanism remains to be elucidated. In order to study the function(s) of this protein, we constructed expression vectors containing the coding sequence of the ICP22 gene placed under the control of the SV40 or HCMV promoter. After cell transfection, ICP22 synthesis was studied by immunoblotting, using a specific antiserum. In transient expression experiments in COS cells in which the ICP22 vector was under the control of the SV40 promoter, we found that ICP22 was able to inhibit chloramphenicol acetyltransferase (CAT) expression under the control of either the alpha 22 (IE4) promoter or other immediate-early promoters, such as alpha 4 (IE3), alpha 0 (IE1), and alpha 27 (IE2). CAT expression under the control of the alpha 4 (IE3) promoter was inhibited in these cells by expression of ICP22 under the control of the HCMV promoter; it was also inhibited in RAT-1 cells by ICP22 expressed under the control of the SV40 or HCMV promoter. In contrast, CAT expression directed by the SV40 or HCMV promoters was only weakly or not inhibited by the ICP22 vectors. We also constructed an expression vector for UL13, a gene whose product is implicated in the phosphorylation of ICP22. Although CAT expression under the control of the alpha 4 (IE3) promoter was also negatively regulated by the UL13 gene product, the effects of the ICP22 (directed by the SV40 or HCMV promoter) and UL13 vectors were not synergistic; furthermore, at a particular molar ratio of the two vectors, inhibition of CAT activity was partially reversed. The results in the present work suggest that ICP22 can negatively regulate the expression of immediate-early viral genes and that its phosphorylation by UL13 protein kinase might be involved in the modulation of its function.
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PMID:Characterization of regulatory functions of the HSV-1 immediate-early protein ICP22. 895 59

The functionality of a 3422-base pair promoter fragment from the mouse alpha(1B)-adrenergic receptor (alpha(1B)AR) gene was examined. This fragment, cloned from a mouse genomic library, was found to have significant sequence homology to the known human and rat alpha(1B)AR promoters. However, the consensus motif of several key cis-acting elements is not conserved among the rat, human, and mouse genes, suggesting species specificity. Confirming fidelity of the murine promoter, robust in vitro expression of a chloramphenicol acetyltransferase (CAT) reporter was detected in known alpha(1B)AR-expressing BC(3)H1, NB41A3, and DDT(1)MF-2 cells transiently transfected with a promoter-CAT construct. Conversely, minimal CAT expression was detected in known alpha(1B)AR-negative RAT-1 and R3T3 cells. These findings were extended by transfecting the same promoter-CAT construct into various primary cell types. In support of the hypothesis that alpha(1)ARs are differentially expressed in the smooth muscle of the vasculature, primary cultures of superior mesenteric and renal artery vascular smooth muscle cells showed significantly stronger CAT expression than did vascular smooth muscle cells derived from pulmonary, femoral, and iliac arteries. Primary osteoblastic bone-forming cells, which are known to be alpha(1B)AR negative, showed minimal CAT expression. Indicating regulatory function through cis-acting elements, RAT-1, R3T3, NB41A3, BC(3)H1, and DDT(1)MF2 cells transfected with the promoter-CAT construct all showed increased CAT production when challenged with forskolin or hypoxic conditions. Additionally, tissue-specific regulation of the promoter was observed when cells were simultaneously challenged with both forskolin and hypoxia. These results collectively demonstrate that a 3.4-kb PvuII fragment of the murine alpha(1B)AR gene promoter can: 1) drive tissue-specific production of a CAT reporter in both clonal and primary cell lines; and 2) confer tissue-specific regulation of that CAT reporter when induced by challenge with forskolin and/or hypoxic conditions.
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PMID:Cloning, cell-type specificity, and regulatory function of the mouse alpha(1B)-adrenergic receptor promoter. 1057 57