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Transcriptional Inhibitor (transcriptional + inhibitor)

Distribution by Scientific Domains
Life Sciences80%

Selected Abstracts

A novel, promoter-based, target-specific assay identifies 2-deoxy- d -glucose as an inhibitor of globotriaosylceramide biosynthesis

FEBS JOURNAL, Issue 18 2009
Tetsuya Okuda
Abnormal biosynthesis of globotriaosylceramide (Gb3) is known to be associated with Gb3-related diseases, such as Fabry disease. The Gb3 synthase gene (Gb3S) codes for ,1,4-galactosyltransferase, which is a key enzyme involved in Gb3 biosynthesis in vivo. Transcriptional repression of Gb3S is a way to control Gb3 biosynthesis and may be a suitable target for the treatment of Gb3-related diseases. To find a transcriptional inhibitor for Gb3S, we developed a convenient cell-based chemical screening assay system by constructing a fusion gene construct of the human Gb3S promoter and a secreted luciferase as reporter. Using this assay, we identified 2-deoxy- d -glucose as a potent inhibitor for the Gb3S promoter. In cultured cells, 2-deoxy- d -glucose markedly reduced endogenous Gb3S mRNA levels, resulting in a reduction in cellular Gb3 content and a corresponding accumulation of the precursor lactosylceramide. Moreover, cytokine-induced expression of Gb3 on the cell surface of endothelial cells, which is closely related to the onset of hemolytic uremic syndrome in O157-infected patients, was also suppressed by 2-deoxy- d -glucose treatment. These results indicate that 2-deoxy- d -glucose can control Gb3 biosynthesis through the inhibition of Gb3S transcription. Furthermore, we demonstrated the general utility of our novel screening assay for the identification of new inhibitors of glycosphingolipid biosynthesis. [source]

Nucleocytoplasmic transport of fluorescent mRNA in living mammalian cells: nuclear mRNA export is coupled to ongoing gene transcription

GENES TO CELLS, Issue 3 2006
Kazuaki Tokunaga
In eukaryotic cells, export of mRNA from the nucleus to the cytoplasm is one of the essential steps in gene expression. To examine mechanisms involved in the nucleocytoplasmic transport of mRNA, we microinjected fluorescently labeled fushi tarazu (ftz) pre-mRNA into the nuclei of HeLa cells. The injected intron-containing ftz pre-mRNA was distributed to the SC35 speckles and exported to the cytoplasm after splicing by an energy-requiring active process. In contrast, the injected intron-less ftz mRNA was diffusely distributed in the nucleus and then presumably degraded. Interestingly, export of the ftz pre-mRNA was inhibited by treatment with transcriptional inhibitors (actinomycin D, ,-amanitin or DRB). Cells treated with transcriptional inhibitor showed foci enriched with the injected mRNA, which localize side by side with SC35 speckles. Those nuclear foci, referred to as TIDRs (transcriptional-inactivation dependent RNA domain), do not overlap with paraspeckles. In addition, in situ hybridization analysis revealed that the export of endogenous poly(A)+ mRNA is also affected by transcriptional inactivation. These results suggest that nuclear mRNA export is coupled to ongoing gene transcription in mammalian cells. [source]

Insights into the function of the WhiB-like protein of mycobacteriophage TM4 , a transcriptional inhibitor of WhiB2

MOLECULAR MICROBIOLOGY, Issue 3 2010
Jan Rybniker
Summary WhiB-like proteins of actinomycetes are known to co-ordinate iron-sulfur (Fe-S) clusters and are believed to have regulatory functions in many essential bacterial processes. The systematic determination of the genome sequences of mycobacteriophages has revealed the presence of several whiB -like genes in these viruses. Here we focussed on the WhiB-like protein of mycobacteriophage TM4, WhiBTM4. We provide evidence that this viral protein is capable of co-ordinating a Fe-S cluster. The UV-visible absorption spectra obtained from freshly purified and reconstituted WhiBTM4 were consistent with the presence of an oxygen sensitive [2Fe-2S] cluster. Expression of WhiBTM4 in the mycobacterial host led to hindered septation resembling a WhiB2 knockout phenotype whereas basal expression of WhiBTM4 led to superinfection exclusion. The quantification of mRNA-levels during phage infection showed that whiBTM4 is a highly transcribed early phage gene and a dominant negative regulator of WhiB2. Strikingly, both apo-WhiB2 of Mycobacterium tuberculosis and apo-WhiBTM4 were capable of binding to the conserved promoter region upstream of the whiB2 gene indicating that WhiB2 regulates its own synthesis which is inhibited in the presence of WhiBTM4. Thus, we provide substantial evidence supporting the hypothesis of viral and bacterial WhiB proteins being important Fe-S containing transcriptional regulators with DNA-binding capability. [source]

Nucleocytoplasmic transport of fluorescent mRNA in living mammalian cells: nuclear mRNA export is coupled to ongoing gene transcription

GENES TO CELLS, Issue 3 2006
Kazuaki Tokunaga
In eukaryotic cells, export of mRNA from the nucleus to the cytoplasm is one of the essential steps in gene expression. To examine mechanisms involved in the nucleocytoplasmic transport of mRNA, we microinjected fluorescently labeled fushi tarazu (ftz) pre-mRNA into the nuclei of HeLa cells. The injected intron-containing ftz pre-mRNA was distributed to the SC35 speckles and exported to the cytoplasm after splicing by an energy-requiring active process. In contrast, the injected intron-less ftz mRNA was diffusely distributed in the nucleus and then presumably degraded. Interestingly, export of the ftz pre-mRNA was inhibited by treatment with transcriptional inhibitors (actinomycin D, ,-amanitin or DRB). Cells treated with transcriptional inhibitor showed foci enriched with the injected mRNA, which localize side by side with SC35 speckles. Those nuclear foci, referred to as TIDRs (transcriptional-inactivation dependent RNA domain), do not overlap with paraspeckles. In addition, in situ hybridization analysis revealed that the export of endogenous poly(A)+ mRNA is also affected by transcriptional inactivation. These results suggest that nuclear mRNA export is coupled to ongoing gene transcription in mammalian cells. [source]

Symposium 1: Regulation of Neural Development by BMP and Activin Family Members

JOURNAL OF NEUROCHEMISTRY, Issue 2002
J. A. Kessler
The effects of BMP family members on stem cell lineage commitment depend upon the developmental age of the stem cell. BMP4 promotes apoptosis of early ventricular zone (VZ) stem cells, neuronal differentiation of later stage VZ cells, and astroglial differentiation of subventricular zone (SVZ) cells. BMP4 inhibits oligodendroglial lineage commitment at all stages of development. The effects of BMP4 in promoting commitment to a specific lineage reflect active suppression of alternate lineages by transcriptional inhibitors including ID and HEY family members and others. For example, BMP mediated increases in ID expression in SVZ stem cells suppress both oligodendroglial and neuronal differentiation. Similarly HEY 1 expression in SVZ cells suppresses neuronal differentiation, whereas HEYL expression by VZ cells inhibits glial differentiation and promotes neurogenesis. The differing effects of the BMPs on VZ and SVZ stem cells reflect also differences in the complement of transcription factors that are expressed. For example, VZ stem cells express high levels of neurogenin and HEY L whereas SVZ stem cells express lower levels of these factors but higher levels of HEY1. Thus lineage commitment by stem cells reflects interplay among stimulatory and inhibitory transcription factors, and responses to the BMPs depend upon the repertoire of transcription factors already expressed by the cell. [source]