Search results for "regulator"

O2 as the regulatory signal for FNR-dependent gene regulation in Escherichia coli

1996

With an oxystat, changes in the pattern of expression of FNR-dependent genes from Escherichia coli were studied as a function of the O2 tension (pO2) in the medium. Expression of all four tested genes was decreased by increasing O2. However, the pO2 values that gave rise to half-maximal repression (pO(0.5)) were dependent on the particular promoter and varied between 1 and 5 millibars (1 bar = 10(5) Pa). The pO(0.5) value for the ArcA-regulated succinate dehydrogenase genes was in the same range (pO(0.5) = 4.6 millibars). At these pO2 values, the cytoplasm can be calculated to be well supplied with O2 by diffusion. Therefore, intracellular O2 could provide the signal to FNR, suggesting that…

O2-sensing and O2-dependent gene regulation in facultatively anaerobic bacteria.

1995

Availability of O2 is one of the most important regulatory signals in facultatively anaerobic bacteria. Various two- or one-component sensor/regulator systems control the expression of aerobic and anaerobic metabolism in response to O2. Most of the sensor proteins contain heme or Fe as cofactors that interact with O2 either by binding or by a redox reaction. The ArcA/ArcB regulator of aerobic metabolism in Escherichia coli may use a different sensory mechanism. In two-component regulators, the sensor is located in the cytoplasmic membrane, whereas one-component regulators are located in the cytoplasm. Under most conditions, O2 can readily reach the cytoplasm and could provide the signal in …

Novel isatin-derived molecules activate p53 via interference with Mdm2 to promote apoptosis

2018

International audience; The p53 protein is a key tumor suppressor in mammals. In response to various forms of genotoxic stress p53 stimulates expression of genes whose products induce cell cycle arrest and/or apoptosis. An E3-ubiquitin ligase, Mdm2 (mouse-double-minute 2) and its human ortholog Hdm2, physically interact with the amino-terminus of p53 to mediate its ubiquitin-mediated degradation via the proteasome. Thus, pharmacological inhibition of the p53-Mdm2 interaction leads to overall stabilization of p53 and stimulation of its anti-tumorigenic activity. In this study we characterize the biological effects of a novel class of non-genotoxic isatin Schiff and Mannich base derivatives (…

Priming for JA-dependent defenses using hexanoic acid is an effective mechanism to protect Arabidopsis against B. cinerea

2011

Abstract Soil drench treatments with hexanoic acid can effectively protect Arabidopsis plants against Botrytis cinerea through a mechanism based on a stronger and faster accumulation of JA-dependent defenses. Plants impaired in ethylene, salicylic acid, abscisic acid or glutathion pathways showed intact protection by hexanoic acid upon B. cinerea infection. Accordingly, no significant changes in the SA marker gene PR-1 in either the SA or ABA hormone balance were observed in the infected and treated plants. In contrast, the JA signaling pathway showed dramatic changes after hexanoic acid treatment, mainly when the pathogen was present. The impaired JA mutants, jin1-2 and jar1 , were unable …

Langerhans Cells Prevent Autoimmunity via Expansion of Keratinocyte Antigen-Specific Regulatory T Cells

2017

Langerhans cells (LCs) are antigen-presenting cells in the epidermis whose roles in antigen-specific immune regulation remain incompletely understood. Desmoglein 3 (Dsg3) is a keratinocyte cell-cell adhesion molecule critical for epidermal integrity and an autoantigen in the autoimmune blistering disease pemphigus. Although antibody-mediated disease mechanisms in pemphigus are extensively characterized, the T cell aspect of this autoimmune disease still remains poorly understood. Herein, we utilized a mouse model of CD4+ T cell-mediated autoimmunity against Dsg3 to show that acquisition of Dsg3 and subsequent presentation to T cells by LCs depended on the C-type lectin langerin. The lack of…

cFLIPL Inhibits Tumor Necrosis Factor-related Apoptosis-inducing Ligand-mediated NF-κB Activation at the Death-inducing Signaling Complex in Human Ke…

2004

Human keratinocytes undergo apoptosis following treatment with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) via surface-expressed TRAIL receptors 1 and 2. In addition, TRAIL triggers nonapoptotic signaling pathways including activation of the transcription factor NF-kappaB, in particular when TRAIL-induced apoptosis is blocked. The intracellular protein cFLIP(L) interferes with TRAIL-induced apoptosis at the death-inducing signaling complex (DISC) in many cell types. To study the role of cFLIP(L) in TRAIL signaling, we established stable HaCaT keratinocyte cell lines expressing varying levels of cFLIP(L). Functional analysis revealed that relative cFLIP(L) levels correlat…

Mucosal T cells: mediators or guardians of inflammatory bowel disease?

2003

Because the mucosal immune system is continuously exposed to a myriad of potentially harmful environmental antigens, it frequently reacts with antiinflammatory/regulatory T cell responses driven by TGF-β-producing T H 3 cells and IL-10-producing regulatory T cells. Intestinal inflammation in patients with inflammatory bowel diseases is thought to result from an overwhelming uncontrolled activation of the mucosal immune system induced by antigens of the normal luminal flora in genetically susceptible individuals. Inflammatory bowel disease appears to be mediated by subsets of CD4 + T lymphocytes or NK T cells secreting high levels of proinflammatory cytokines such as TNF-α. The increased exp…

Induction of Regulatory T Cells in Leishmania major‒Infected BALB/c Mice Does Not Require Langerin+ Dendritic Cells

2021

Langerhans cells are negative regulators of the anti-Leishmania response

2011

Langerhans cells suppress the immune response to low-dose Leishmania major infection in part by inducing regulatory T cells.

Effects of the insect growth regulator cyromazine on the fecundity, fertility and offspring development of Mediterranean fruit fly,Ceratitis capitata…

1995

Addition of cyromazine to adult diet affected negatively the development of Ceratitis capitata Wied. (Dipt., Tephritidae) offspring. Five concentrations of cyromazine (0.00001 mg/ml, 0.01 mg/ml, 0.1 mg/ml, 1 mg/ml and 10 mg/ml) have been tested. A reduction of Mediterranean fruit fly populations has been found mainly due to the effects of fertility and larval development. At these concentrations, cyromazine does not affect Ceratitis capitata fecundity.