Search results for " Gene Expression"
showing 10 items of 695 documents
Cadmium regulation of apoptotic and stress response genes in tumoral and immortalized epithelial cells of the human breast
2008
Cadmium (Cd) is a widely-disseminated metal which can be imported and accumulated in living cells thereby drastically interfering with their biological mechanisms. Increasing interest has been recently focused on the elucidation of the cellular and molecular aspects of Cd-dependent regulation of gene expression and signal transduction pathways in different model system. Concerning breast cancer, very limited studies have been produced so far on the role played by Cd on estrogen receptor-negative human breast cancer cells, that are expected to be insensitive to the already-proven metallo-estrogenic effect exerted by Cd on the estrogen receptor-positive cell counterparts. Here, we have examin…
Let-7d miRNA Shows Both Antioncogenic and Oncogenic Functions in Osteosarcoma-Derived 3AB-OS Cancer Stem Cells
2015
Osteosarcoma (OS), an aggressive highly invasive and metastatic bone-malignancy, shows therapy resistance and recurrence, two features that likely depend on cancer stem cells (CSCs), which hold both self-renewing and malignant potential. So, effective anticancer therapies against OS should specifically target and destroy CSCs. We previously found that the let-7d microRNA was downregulated in the 3AB-OS-CSCs, derived from the human OS-MG63 cells. Here, we aimed to assess whether let-7d modulation affected tumorigenic and stemness properties of these OS-CSCs. We found that let-7d-overexpression reduced cell proliferation by decreasing CCND2 and E2F2 cell-cycle-activators and increasing p21 an…
Metazoan Circadian Rhythm: Toward an Understanding of a Light-Based Zeitgeber in Sponges
2013
In all eukaryotes, the 24-h periodicity in the environment contributed to the evolution of the molecular circadian clock. We studied some elements of a postulated circadian clock circuit in the lowest metazoans, the siliceous sponges. First, we identified in the demosponge Suberites domuncula the enzyme luciferase that generates photons. Then (most likely), the photons generated by luciferase are transmitted via the biosilica glass skeleton of the sponges and are finally harvested by cryptochrome in the same individual; hence, cryptochrome is acting as a photosensor. This information-transduction system, generation of light (luciferase), photon transmission (through the siliceous spicules),…
Glucocorticoid receptor regulates organic cation transporter 1 (OCT1, SLC22A1) expression via HNF4α upregulation in primary human hepatocytes
2013
Abstract Background Organic cation transporter 1 (OCT1, SLC22A1) is a membrane transporter that is important for therapeutic effect of the antidiabetic drug metformin. Its liver-specific expression in hepatocytes is strongly controlled by hepatocyte nuclear factor-4α (HNF4α). HNF4α expression and transcriptional activity have been demonstrated to be augmented by glucocorticoid receptor (GR) in human hepatocytes and rodent livers. Methods It was examined whether GR activation indirectly induces OCT1 gene expression via HNF4α up-regulation in primary human hepatocytes.We also examined which other transcription factors are involved in OCT1 gene expression and whether they are regulated by dexa…
Coordinated Sumoylation and Ubiquitination Modulate EGF Induced EGR1 Expression and Stability
2011
Background Human early growth response-1 (EGR1) is a member of the zing-finger family of transcription factors induced by a range of molecular and environmental stimuli including epidermal growth factor (EGF). In a recently published paper we demonstrated that integrin/EGFR cross-talk was required for Egr1 expression through activation of the Erk1/2 and PI3K/Akt/Forkhead pathways. EGR1 activity and stability can be influenced by many different post-translational modifications such as acetylation, phosphorylation, ubiquitination and the recently discovered sumoylation. The aim of this work was to assess the influence of sumoylation on EGF induced Egr1 expression and/or stability. Methods We …
Robust dynamical pattern formation from a multifunctional minimal genetic circuit.
2010
Abstract Background A practical problem during the analysis of natural networks is their complexity, thus the use of synthetic circuits would allow to unveil the natural mechanisms of operation. Autocatalytic gene regulatory networks play an important role in shaping the development of multicellular organisms, whereas oscillatory circuits are used to control gene expression under variable environments such as the light-dark cycle. Results We propose a new mechanism to generate developmental patterns and oscillations using a minimal number of genes. For this, we design a synthetic gene circuit with an antagonistic self-regulation to study the spatio-temporal control of protein expression. He…
Tick Salivary Sialostatin L Represses the Initiation of Immune Responses by Targeting IRF4-Dependent Transcription in Murine Mast Cells
2015
Abstract Coevolution of ticks and the vertebrate immune system has led to the development of immunosuppressive molecules that prevent immediate response of skin-resident immune cells to quickly fend off the parasite. In this article, we demonstrate that the tick-derived immunosuppressor sialostatin L restrains IL-9 production by mast cells, whereas degranulation and IL-6 expression are both unaffected. In addition, the expression of IL-1β and IRF4 is strongly reduced in the presence of sialostatin L. Correspondingly, IRF4- or IL-1R–deficient mast cells exhibit a strong impairment in IL-9 production, demonstrating the importance of IRF4 and IL-1 in the regulation of the Il9 locus in mast cel…
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…
Promoter activity of the sea urchin (Paracentrotus lividus) nucleosomal H3 and H2A and linker H1 a-histone genes is modulated by enhancer and chromat…
2009
Core promoters and chromatin insulators are key regulatory elements that may direct a transcriptional enhancer to prefer a specific promoter in complex genetic loci. Enhancer and insulator flank the sea urchin (Paracentrotus lividus) alpha-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. This article deals with the specificity of interaction between the H2A enhancer-bound MBF-1 activator and histone gene promoters, and with the mechanism that leads the H1 transcripts to peak at about one-third of the value for nucleosomal H3 and H2A mRNAs. To this end, in vivo competition assays of enhancer and insulator functions were performed. Our evidence su…
The Transcription Factors TBX2 and TBX3 Interact with Human Papillomavirus 16 (HPV16) L2 and Repress the Long Control Region of HPVs
2013
ABSTRACT The minor capsid protein L2 of human papillomaviruses (HPVs) has multiple functions during the viral life cycle. Although L2 is required for effective invasion and morphogenesis, only a few cellular interaction partners are known so far. Using yeast two-hybrid screening, we identified the transcription factor TBX2 as a novel interaction partner of HPV type 16 (HPV16) L2. Coimmunoprecipitations and immunofluorescence analyses confirmed the L2-TBX2 interaction and revealed that L2 also interacts with TBX3, another member of the T-box family. Transcription of the early genes during HPV infection is under the control of an upstream enhancer and early promoter region, the long control r…