Search results for "Porte"
showing 10 items of 1894 documents
A major cysteine proteinase, EPB, in germinating barley seeds: structure of two intronless genes and regulation of expression
1996
The barley cysteine proteinase B (EPB) is the main protease responsible for the degradation of endosperm storage proteins providing nitrogenous nutrients to support the growth of young seedlings. The expression of this enzyme is induced in the germinating seeds by the phytohormone, gibberellin, and suppressed by another phytohormone, abscisic acid. In situ hybridization experiments indicate that EPB is expressed in the scutellar epithelium within 24 h of seed germination, but the aleurone tissue surrounding the starchy endosperm eventually becomes the main tissue expressing this enzyme. The EPB gene family of barley consists of two very similar genes, EPB1 and EPB2, both of which have been …
Generation and characterization of tTS-H4: a novel transcriptional repressor that is compatible with the reverse tetracycline-controlled TET-ON system
2007
Background Conditional gene regulatory systems ensuring tight and adjustable expression of therapeutic genes are central for developing future gene therapy strategies. Among various regulatory systems, tetracycline-controlled gene expression has emerged as a safe and reliable option. Moreover, the tightness of tetracycline-regulated gene switches can be substantially improved by complementing transcriptional activators with antagonizing repressors. Methods To develop novel tetracycline-responsive transcriptional repressors, we fused various transcriptional silencing domains to the TetR (B/E) DNA-binding and dimerization domain of the Tn10-encoded tetracycline resistance operon (TetR (B/E)).…
Regulation ofMUC1Expression in Human Mammary Cell Lines by the c-ErbB2 and Ras Signaling Pathways
2001
The MUC1 protein is a highly O-glycosylated transmembrane molecule that is expressed at the luminal surface of most glandular epithelial cells and is upregulated in carcinomas. Here, we report the effect of the activation of the c-ErbB2 --Ras pathway on the expression of the MUC1 gene in the nontumorigenic mammary cell lines MTSV1-7 and HB2 and in the malignant cell lines T47D and ZR75. Endogenous levels of MUC1 mRNA and protein in HB2 clones permanently overexpressing c-ErbB2 or V12-H-Ras were markedly reduced compared with levels in the parental cell lines. Furthermore, in transient transfection assays, the transcription of a CAT reporter construct driven by the MUC1 promoter was inhibite…
Analysis of expression of the gene encoding for the nuclear autoantigen La/SS-B using reporter gene constructs.
1998
In earlier studies mRNA isoforms encoding for the nuclear autoantigen La were identified. In an alternative La mRNA form the exon 1 was replaced with the exon 1'. Moreover, exon 1' La mRNAs were found to start at different 5'-regions. In dependence on the 5'-start the exon 1' La mRNAs encoded for up to three open reading frames upstream of the La frame, which starts in the exon 2. The exon 1' was located in the intron about 70 nts downstream of the exon 1. The exon 1' La mRNA was proposed to be the result of a promoter switch in combination with an alternative splicing mechanism. The commonly used technique to study the expression of a eucaryotic gene is to fuse a reportergene immediately d…
Transcription factors involved in the expression of SLC28 genes in human liver parenchymal cells.
2007
Human nucleoside transporters are encoded by SLC28 (hCNTs) and SLC29 (hENTs) genes. These proteins mediate the uptake of anticancer and some antiviral drugs and are also suitable candidates to facilitate nucleoside-derived drug uptake into hepatocytes for detoxification. Despite the putative relevance of these genes in liver physiology, the human SLC28 and SLC29 expression pattern is not known and suitable cell models are not available. These issues have been addressed by examining NT expression in human liver and primary cultures of human hepatocytes. Moreover, the effect of specific liver enriched transcription factors (LETFs) in hCNTs expression has been analyzed. Human hepatocytes expre…
Sea urchin neural alpha 2 tubulin gene: isolation and promoter analysis
2004
Abstract Expression of Tα2 gene, during sea urchin Paracentrotus lividus development, is spatially and temporally regulated. In order to characterize this gene, we isolated the relevant genomic sequences and scanned the isolated 5 ′ -flanking region in searching for cis -regulatory elements required for proper expression. Gel mobility shift and footprinting assays, as well as reporter gene (CAT and β-gal) expression assays, were used to address cis -regulatory elements involved in regulation. Here we report that an upstream 5 ′ -flanking fragment of PlTα2 gene drives temporal expression of reporter genes congruent with that of endogenous Tα2 gene. The fragment contains cis -elements able to…
Towards light-mediated sensing of bacterial comfort
2013
Abstract Bacterial comfort is central to biotechnological applications. Here, we report the characterization of different sensoring systems, the first step within a broader synthetic biology-inspired light-mediated strategy to determine Escherichia coli perception of environmental factors critical to bacterial performance. We did so by directly ‘asking’ bacterial cultures with light-encoded questions corresponding to the excitation wavelength of fluorescent proteins placed under the control of environment-sensitive promoters. We built four genetic constructions with fluorescent proteins responding to glucose, temperature, oxygen and nitrogen; and a fifth construction allowing UV-induced exp…
Differential Regulation of CCL22 Gene Expression in Murine Dendritic Cells and B Cells
2005
Abstract The activated T cell-attracting CC chemokine CCL22 is expressed by stimulated B cells and mature dendritic cells (DC). We have cloned and sequenced the complete mouse gene, including 4 kb of the 5′-flanking promoter region, and detected two distinct sites for initiation of transcription by 5′-RACE. Reporter gene assays indicate that the promoter reflects the specificity of the endogenous gene. Within the proximal promoter region, we identified potential binding sites for NF-κB, Ikaros, and a putative GC box. All three regions bind proteins. The NF-κB site was shown to specifically bind NF-κB subunits p50 and p65 from nuclear extracts of LPS-stimulated B cells, B cell line A20/2J, T…
Transcriptional Regulation of Human CYP3A4 Basal Expression by CCAAT Enhancer-Binding Protein α and Hepatocyte Nuclear Factor-3γ
2003
Cytochrome P450 3A4 (CYP3A4) is involved in the metabolism of more than 50% of currently used therapeutic drugs, yet the mechanisms that control CYP3A4 basal expression in liver are poorly understood. Several putative binding sites for CCAAT/enhancer-binding protein (C/EBP) and hepatic nuclear factor 3 (HNF-3) were found by computer analysis in CYP3A4 promoter. The use of reporter gene assays, electrophoretic mobility shift assays, and site-directed mutagenesis revealed that one proximal and two distal C/EBP alpha binding sites are essential sites for the trans-activation of CYP3A4 promoter. No trans-activation was found in similar reporter gene experiments with a HNF-3 gamma expression vec…
Physiological activation of the IgH 3' enhancer in B lineage cells is not blocked by Pax-5.
1996
The mouse 3' enhancer contains a high-affinity binding site for the paired box protein Pax-5. Here, we demonstrate by genomic footprinting that the rat 3' enhancer contains a low-affinity binding site for Pax-5, which is occupied in activated splenic B cells. Thus, binding of Pax-5 to the IgH 3' enhancer appears to be evolutionarily conserved in rodents. Analysis of Pax-5 expression in primary B cells demonstrates that Pax-5 remains expressed after 4 days of lipopolysaccharide (LPS) induction, but is down-regulated in 5-day stimulated cells. Similarly, the expression of Pax-5 is down-regulated in vivo in activated large splenocytes, in contrast to small resting cells. Multimerization of the…