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)

Integration of foreign genes into plant genomes by the Agrobacterium T-DNA transfer system has been considered to occur at random. It has been speculated that the chromosomal structure of the integration site might affect the expression pattern of the introduced genes. To gain insight into the molecular structure of T-DNA integration sites and its possible impact on gene expression, we have examined plant DNA sequences in the vicinity of T-DNA borders. Analysis of a transgenic petunia plant containing a chloramphenicol acetyltransferase (CAT) gene regulated by the hemoglobin promoter (PAR) from Parasponia andersonii revealed a scaffold attachment region (SAR) close to one T-DNA end. In addition to having strong binding affinities for both animal and plant nuclear scaffolds this petunia SAR element is as active in mammalian cells as the authentic elements from mammalian sources.
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PMID:A plant scaffold attached region detected close to a T-DNA integration site is active in mammalian cells. 805 30

The urokinase-type plasminogen activator receptor (u-PAR) facilitates extracellular matrix proteolysis by accelerating plasmin formation at the cell surface. The present study was undertaken to identify elements in the u-PAR promoter required for the elevated expression of this binding site. Toward this end, we used two cultured colon cancer cell lines; one (RKO) has a transcriptionally activated u-PAR gene, and the other (GEO) overexpresses the receptor only after phorbol ester treatment. A chloramphenicol acetyltransferase (CAT) reporter driven by 398 nucleotides of 5' regulatory sequence of the u-PAR gene was strongly activated in the RKO cells, which displays approximately 3 x 10(5) receptors/cell. A region of this promoter between -197 and -8 was required for optimal expression, as indicated using a CAT reporter driven by 5' deleted fragments. DNase I footprinting revealed three protected regions (I, -190 to -171; II, -148 to -124; and III, -99 to -70) in this part of the promoter. Mutation of an AP-1 binding site at -184 within region I reduced activation of the promoter by 85%. Deletion of either region II or III also reduced promoter activity by over 60%. An oligonucleotide spanning the AP-1 motif at -184 bound, specifically, nuclear factors from RKO cells, and antibodies specific for Jun-D, c-Jun, or Fra-1 proteins supershifted the complex indicating the presence of these proteins. The amount of these factors was reduced in GEO cells in which the u-PAR gene is only weakly transcriptionally activated. Expression of a vector encoding a wild-type Jun-D cDNA increased u-PAR promoter activity in GEO cells. Conversely, transfection of RKO cells with a transactivation domain-lacking Jun-D expression construct resulted in a dose-dependent decrease in u-PAR promoter activity. Treatment of GEO cells with phorbol ester increased u-PAR mRNA and the activity of a CAT reporter driven by the wild-type but not the AP-1 (-184)-mutated u-PAR promoter, and this was associated with a strong induction in the amount of Jun-D, c-Jun, and c-Fos. Methylation interference studies using a fragment of the u-PAR promoter (spanning -201 to -150) bound with nuclear extracted proteins from RKO cells, and phorbol 12-myristate 13-acetate-treated and -untreated GEO cells showed that the contact points corresponded to the AP-1 binding site at -184. Thus, the elevated expression of u-PAR in RKO cells, which constitutively produces this binding site, as well as in phorbol 12-myristate 13-acetate-stimulated GEO cells requires an AP-1 motif located 184 bp upstream of the transcriptional start site.
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PMID:Requirement of an upstream AP-1 motif for the constitutive and phorbol ester-inducible expression of the urokinase-type plasminogen activator receptor gene. 879 12