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)

As an approach to understanding the molecular mechanism(s) of thymic gene expression mediated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), we investigated the effect of TCDD on expression of prostaglandin G/H synthase-2 (PGHS-2) in rat thymocytes by reverse transcription-polymerase chain reaction. Incubation of thymocytes with increasing doses of TCDD resulted in inhibition of PGHS-2 gene expression in a concentration-dependent manner, with an IC50 of 10 nM. In contrast, TCDD had no appreciable effect on expression of glyceraldehyde phosphate dehydrogenase. Because the xenobiotic-responsive element is conserved in the PGHS-2 promoter from several animal species, it seems likely that inhibition of PGHS-2 expression by TCDD may occur at the level of transcription. To test this hypothesis in cultured thymocytes, we characterized the Ah receptor in the thymoma cell line WEHI 7.1. Reverse transcription-polymerase chain reaction experiments indicated that TCDD inhibited PGHS-2 expression in this cell line. Sucrose density gradient centrifugation experiments indicated that WEHI 7.1 cytosol exhibited 9 to 10S ligand-binding activity characteristic of the Ah receptor. The viability of WEHI 7.1 cells incubated with TCDD was comparable to that of control cells, whereas dexamethasone induced toxicity in a concentration-dependent manner. Transient transfection experiments using PGHS-2 promoter fragments ligated into a chloramphenicol acetyltransferase reporter plasmid suggested that TCDD inhibits PGHS-2 transcription, and deletion of the xenobiotic-responsive element failed to exhibit this repression. These results demonstrate that TCDD is a potent inhibitor of PGHS-2 gene expression, and they represent the first mechanistic evidence for TCDD-dependent inhibition of transcription in thymocytes.
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PMID:2,3,7,8-tetrachlorodibenzo-p-dioxin modulates expression of the prostaglandin G/H synthase-2 gene in rat thymocytes. 896 84

In congenital heart disease with left- or right-sided obstruction, prostaglandin E (PGE)1 or PGE2 is infused to maintain ductus arteriosus (DA) patency. We hypothesized that transfection of the DA with PGE synthase would lead to a greater production of PGE2 in situ and, hence, patency of the DA. The cDNA for human prostaglandin synthase was sequenced and ligated into a eukaryotic expression vector. The negative control was created by ligating the cDNA encoding the bacterial protein chloramphenicol acetyltransferase into the same plasmid. Transfection (600 microg DNA) was achieved in lambs within the first 24 h of life using the hemagglutinating virus of Japan (HVJ)-liposome transfection method with a custom-made, basket-weave-perforated catheter. Echocardiography was performed to assess DA patency until the time of sacrifice. To confirm expression of the transgene, PGE2 concentration was measured in organ culture of the DA by immunoassay and by Western immunoblotting of homogenized DA tissue. Patency of the DA was demonstrated by color Doppler in all the lambs (7/7) in which the PGE synthase was delivered, whereas functional closure was seen in the control group (6/6). The PGE2 concentration in the culture medium of the explanted DA in the treatment group was 3-fold higher than that of the control groups. Western immunoblotting confirmed the presence of PGE synthase in the treatment group. Gene transfer of PGE synthase to the DA is feasible and will maintain patency for at least 1 wk.
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PMID:Gene transfer of prostaglandin synthase maintains patency of the newborn lamb arterial duct. 1618 5