Search results for "Downregulation"
showing 10 items of 460 documents
A homolog of the putative tumor suppressor QM in the sponge Suberites domuncula: downregulation during the transition from immortal to mortal (apopto…
1999
Abstract The activation of components of the transcription factors such as AP-1 or c-jun is essential for a physiological response of metazoan cells during aging. The activity of such proto-oncoproteins is under enzymatic control. The function of c-jun is additionally modulated by the QM protein. Here, we studied the expression of the gene, encoding the QM-like protein in the sponge Suberites domuncula . These animals contain high levels of telomerase in their somatic cells. To understand the switch from telomerase-positive immortal cells to telomerase-negative mortal cells which undergo apoptosis, the expression of the QM-like gene was measured in this system. The cDNA, termed QMSD , encod…
Transcription of different exons 1 of the human neuronal nitric oxide synthase gene is dynamically regulated in a cell- and stimulus-specific manner.
2003
An extensive screening of the human neuronal nitric oxide synthase (nNOS) mRNAs in various human tissues and cell lines unraveled an extreme complexity in the transcription of this gene. Using 5'rapid amplification of cDNA ends (5'-RACE), ten different exons 1 (named 1a-1l) were identified. They were spliced in a cell-specific manner to a common exon 2, which bears the translational start site. Three first exons (1 d, 1g and 1f) were used predominantly for the transcription of the nNOS gene (146 out of 197 5'-RACE clones contained these exons). Exon 1 k was found alone, but in many instances was interposed between exons 1 b, 1d, 1g, 1 i or 1j and the common exon 2. In addition to the cell-s…
Nuclear aggregation of olfactory receptor genes governs their monogenic expression.
2012
SummaryGene positioning and regulation of nuclear architecture are thought to influence gene expression. Here, we show that, in mouse olfactory neurons, silent olfactory receptor (OR) genes from different chromosomes converge in a small number of heterochromatic foci. These foci are OR exclusive and form in a cell-type-specific and differentiation-dependent manner. The aggregation of OR genes is developmentally synchronous with the downregulation of lamin b receptor (LBR) and can be reversed by ectopic expression of LBR in mature olfactory neurons. LBR-induced reorganization of nuclear architecture and disruption of OR aggregates perturbs the singularity of OR transcription and disrupts the…
Estrogens increase transcription of the human endothelial NO synthase gene: analysis of the transcription factors involved.
1998
Abstract —Estrogens have been found to reduce the incidence of cardiovascular disease that has been ascribed in part to an increased expression and/or activity of the vasoprotective endothelial NO synthase (NOS III). Some reports have shown that the level of expression of this constitutive enzyme can be upregulated by estrogens. The current study investigates the molecular mechanism of the NOS III upregulation in human endothelial EA.hy 926 cells. Incubation of EA.hy 926 cells with 17β-estradiol or the more stable 17α-ethinyl estradiol enhanced NOS III mRNA and protein expression up to 1.8-fold, without changing the stability of the NOS III mRNA. There was no enhancement of NOS III mRNA af…
Melatonin induces transcriptional regulation of Bim by FoxO3a in HepG2 cells
2012
Background: Melatonin induces apoptosis in many different cancer cell lines, including hepatocellular carcinoma cells. However, the responsible pathways have not been clearly elucidated. A member of the forkhead transcription factors' family, FoxO3a, has been implicated in the expression of the proapoptotic protein Bim (a Bcl-2-interacting mediator of cell death). In this study, we used human HepG2 liver cancer cells as an in vitro model to investigate whether melatonin treatment induces Bim through regulation by the transcription factor FoxO3a. Methods: Cytotoxicity of melatonin was compared in HepG2 hepatoblastoma cells and primary human hepatocytes. Proapoptotic Bim expression was analys…
Dual effect of ceramide on human endothelial cells: induction of oxidative stress and transcriptional upregulation of endothelial nitric oxide syntha…
2002
Background— Generation of the second-messenger molecule ceramide by stimulated sphingomyelinase activity has been implicated in the inflammatory processes contributing to the pathogenesis of atherosclerosis. However, reports of stimulatory effects of ceramide on endothelial NO production in animal models suggest antiatherosclerotic effects of the molecule. Therefore, we investigated long-term effects of ceramide on NO generation in human endothelial cells. Methods and Results— In human umbilical vein endothelial cells (HUVECs) and in HUVEC-derived EA.hy 926 endothelial cells, C6-ceramide ( N -hexanoyl- d -erythro-sphingosine) reduced the generation of bioactive NO (RFL-6 reporter-cell assa…
The repair of oxidized purines in the DNA of human lymphocytes requires an activation involving NF-YA-mediated upregulation of OGG1.
2014
8-Oxoguanine DNA glycosylase (OGG1), which initiates the repair of DNA purine modifications such as 8-oxo-7,8-dihydroguanine (8-oxoG), is often regarded as a house keeping protein ubiquitously active in mammalian cells. We have analysed the repair rates of oxidized purines generated by photosensitization in peripheral human lymphocytes and observed that the cells were virtually unable to remove these lesions (less than 10% removal within 24h). However, stimulation of the lymphocytes with phytohemagglutinin (PHA) strongly accelerated the repair so that ∼30% of the lesions were repaired within 4h. Within 24h following PHA stimulation and preceding the induction of cell proliferation, Western …
Regulation of the tumor marker Fascin by the viral oncoprotein Tax of human T-cell leukemia virus type 1 (HTLV-1) depends on promoter activation and …
2015
AbstractAdult T-cell leukemia/lymphoma is a highly infiltrative neoplasia of CD4+ T-lymphocytes that occurs in about 5% of carriers infected with the deltaretrovirus human T-cell leukemia virus type 1 (HTLV-1). The viral oncoprotein Tax perturbs cellular signaling pathways leading to upregulation of host cell factors, amongst them the actin-bundling protein Fascin, an invasion marker of several types of cancer. However, transcriptional regulation of Fascin by Tax is poorly understood. In this study, we identified a triple mode of transcriptional induction of Fascin by Tax, which requires (1) NF-κB-dependent promoter activation, (2) a Tax-responsive region in the Fascin promoter, and (3) a p…
Early life stress programming of NG2+ glia transcriptome alters functional properties of voltage gated sodium (Nav) channels and cognitive performance
2020
AbstractThe precise mechanisms underlying the detrimental effects of early life stress (ELS) on adult mental health remain still elusive. To date, most studies have exclusively targeted neuronal populations and not considered neuron-glia crosstalk as a crucially important element for the integrity of stress-related brain function. Here, we have investigated the impact of ELS on a glial subpopulation with unique properties in brain homeostasis, the NG2+ cells. ELS shifted the NG2+ transcriptome towards more mature stages, and these transcriptional effects were dependent on stress-induced glucocorticoids. The functional relevance of one candidate gene, Scn7a, could be confirmed by an increase…
Differential roles of PKCα and PKCɛ in controlling the gene expression of Nox4 in human endothelial cells
2007
NADPH oxidases are major sources of superoxide in the vascular wall. This study investigates the role of protein kinase C (PKC) in regulating gene expression of NADPH oxidases. Treatment of human umbilical vein endothelial cells (HUVEC) and HUVEC-derived EA.hy 926 endothelial cells with phorbol 12-myristate 13-acetate (PMA) or phorbol 12,13-dibutyrate led to a PKC-dependent biphasic expression of the gp91phox homolog Nox4. A downregulation of Nox4 was observed at 6 h and an upregulation at 48 h after phorbol ester treatment. The early Nox4 downregulation was associated with a reduced superoxide production, whereas the late Nox4 upregulation was accompanied by a clear enhancement of superoxi…