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Regulatory Factor (regulatory + factor)
Kinds of Regulatory Factor Selected AbstractsTHE EPITHELIAL BRUSH BORDER Na+/H+ EXCHANGER NHE3 ASSOCIATES WITH THE ACTIN CYTOSKELETON BY BINDING TO EZRIN DIRECTLY AND VIA PDZ DOMAIN-CONTAINING Na+/H+ EXCHANGER REGULATORY FACTOR (NHERF) PROTEINSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2008Boyoung Cha SUMMARY 1The Na+/H+ exchanger NHE3 associates with the actin cytoskeleton by binding ezrin both directly and indirectly. Both types of interaction are necessary for acute regulation of NHE3. Most acute regulation of NHE3 occurs by changes in trafficking via effects on exocytosis and/or endocytosis. However, NHE3 activity can also be regulated without changing the surface expression of NHE3 (change in turnover number). 2A positive amino acid cluster in the a-helical juxtamembrane region in the COOH-terminus of NHE3 (amino acids K516, R520 and R527) is necessary for binding to the protein 4.1, ezrin, radixin, moesin (FERM) domain III of ezrin. Direct binding of NHE3 to ezrin is necessary for many aspects of basal trafficking, including basal exocytosis, delivery from the synthetic pathway and movement of NHE3 in the brush border (BB), which probably contributes to endocytosis over a prolonged period of time. 3In addition, NHE3 binds indirectly to ezrin. The PDZ domain-containing proteins Na+/H+ exchanger regulatory factor (NHERF) 1 and NHERF2, as intermediates in linking NHE3 to ezrin, are necessary for many aspects of NHE3 regulation. The binding of NHERF,ezrin/radixin/moesin to NHE3 occurs in the cytosolic domain of NHE3 between amino acids 475 and 689. This NHERF binding is involved in the formation of the NHE3 complex and restricts NHE3 mobility in the BB. However, it is dynamic; for example, changing in some cases of signalling. Furthermore, NHERF binding is necessary for lysophosphatidic acid stimulation of NHE3 and inhibition of NHE3 by Ca2+, cAMP and cGMP. [source] DONOR ORGANS TRANSGENIC FOR HUMAN COMPLEMENT REGULATORY FACTORS TO OVERCOME XENOGRAFT HYPERACUTE REJECTION: SMALL ANIMAL VX PIG-TO-PRIMATE IN VIVO MODELSNEPHROLOGY, Issue 3 2000Gock H [source] Acute Alcohol Inhibits the Induction of Nuclear Regulatory Factor ,B Activation Through CD14/Toll-Like Receptor 4, Interleukin-1, and Tumor Necrosis Factor Receptors: A Common Mechanism Independent of Inhibitory ,B, Degradation?ALCOHOLISM, Issue 11 2002Pranoti Mandrekar Background Nuclear translocation and DNA binding of the nuclear factor ,B (NF-,B) is an early event in inflammatory cell activation in response to stimulation with bacterial components or cytokines. Cell activation via different receptors culminates in a common pathway leading to NF-,B activation and proinflammatory cytokine induction. We have previously shown that acute alcohol inhibits NF-,B activation by lipopolysaccharide (LPS) in human monocytes. Here we investigated whether acute alcohol treatment of human monocytes also inhibits NF-,B when induced through activation of the interleukin (IL)-1 or tumor necrosis factor (TNF) receptors. Methods Human peripheral blood monocytes were treated with LPS, TNF,, and IL-1, in the presence or absence of 25mM alcohol for 1 hr. NF-,B activation was determined by electrophoretic mobility shift assays using nuclear extracts. Inhibitory ,B, (I,B,) was estimated by Western blotting in cytoplasmic extracts. Chinese hamster ovary cells expressing human CD14 were treated with LPS in the presence or absence of alcohol to study NF-,B and I,B, regulation. Results Our results indicate that acute alcohol inhibits IL-1,- and TNF,-induced NF-,B activation. We further show in CD14/toll-like receptor 4,expressing Chinese hamster ovary cells the specificity of alcohol-mediated inhibition of NF-,B via the toll-like receptor 4/CD14 receptors. Inhibition of NF-,B by acute alcohol was concomitant with decreased levels of the I,B, molecule in the cytoplasm of LPS, IL-1, and TNF,-activated monocytes. Conclusions These data suggest a unique, I,B,-independent pathway for the inhibition of NF-,B activation by acute alcohol in monocytes. Universal inhibition of NF-,B by acute alcohol via these various receptor systems suggests a target for the effects of alcohol in the NF-,B activation cascade that is downstream from I,B, degradation. Further, these results demonstrate that acute alcohol is a potent inhibitor of NF-,B activation by mediators of early (LPS) or late (IL-1, TNF,) stages of inflammation in monocytes. [source] ORIGINAL ARTICLE: IL-6 as a Regulatory Factor of the Humoral Response During PregnancyAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2008Valeria Dubinsky Problem, Regulatory factors seem to be essential to achieve transition from implantation window to placental vascularization. A novel function of interleukin (IL)-6 in the promotion of Th2 differentiation and inhibition of Th1 polarization has been demonstrated. Considering that Th2 response promotes antibody synthesis, we postulate that IL-6 could be modulating the quality of this response during pregnancy by increasing the proportion of blocking asymmetric antibodies. Method of study, We investigated expression of blocking-asymmetric-IgG during pregnancy of CBA/J × DBA/2 abortion model treated with IL-6, with regards to CBA/J × BALB/c. We also determined asymmetric-IgG production in IL-6-deficient pregnant mice. Results, We found that IL-6 treatment increased asymmetric-IgG in multiparous placentas from abortion combination whereas diminished abortion rate. Moreover, asymmetric-IgG proportion was diminished in sera from IL-6-deficient pregnant mice. Conclusion, Modulation of asymmetric antibody synthesis could be another mechanism implicated in the beneficial effect of IL-6 in prevention of murine recurrent abortion. [source] Regulation of virulence determinants in Staphylococcus aureus: complexity and applicationsFEMS MICROBIOLOGY REVIEWS, Issue 2 2004Stéphane Bronner Abstract The virulence of Staphylococcus aureus is essentially determined by cell wall associated proteins and secreted toxins that are regulated and expressed according to growth phases and/or growth conditions. Gene expression is regulated by specific and sensitive mechanisms, most of which act at the transcriptional level. Regulatory factors constitute numerous complex networks, driving specific interactions with target gene promoters. These factors are largely regulated by two-component regulatory systems, such as the agr, saeRS, srrAB, arlSR and lytRS systems. These systems are sensitive to environmental signals and consist of a sensor histidine kinase and a response regulator protein. DNA-binding proteins, such as SarA and the recently identified SarA homologues (SarR, Rot, SarS, SarT, SarU), also regulate virulence factor expression. These homologues might be intermediates in the regulatory networks. The multiple pathways generated by these factors allow the bacterium to adapt to environmental conditions rapidly and specifically, and to develop infection. Precise knowledge of these regulatory mechanisms and how they control virulence factor expression would open up new perspectives for antimicrobial chemotherapy using key inhibitors of these systems. [source] ORIGINAL ARTICLE: IL-6 as a Regulatory Factor of the Humoral Response During PregnancyAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2008Valeria Dubinsky Problem, Regulatory factors seem to be essential to achieve transition from implantation window to placental vascularization. A novel function of interleukin (IL)-6 in the promotion of Th2 differentiation and inhibition of Th1 polarization has been demonstrated. Considering that Th2 response promotes antibody synthesis, we postulate that IL-6 could be modulating the quality of this response during pregnancy by increasing the proportion of blocking asymmetric antibodies. Method of study, We investigated expression of blocking-asymmetric-IgG during pregnancy of CBA/J × DBA/2 abortion model treated with IL-6, with regards to CBA/J × BALB/c. We also determined asymmetric-IgG production in IL-6-deficient pregnant mice. Results, We found that IL-6 treatment increased asymmetric-IgG in multiparous placentas from abortion combination whereas diminished abortion rate. Moreover, asymmetric-IgG proportion was diminished in sera from IL-6-deficient pregnant mice. Conclusion, Modulation of asymmetric antibody synthesis could be another mechanism implicated in the beneficial effect of IL-6 in prevention of murine recurrent abortion. [source] Tulp3 is a critical repressor of mouse hedgehog signalingDEVELOPMENTAL DYNAMICS, Issue 5 2009Don A. Cameron Abstract Precise regulation of the morphogen sonic hedgehog (Shh) and modulation of the Shh signaling pathway is required for proper specification of cell fate within the developing limbs and neural tube, and resultant tissue morphogenesis. Tulp3 (tubby-like protein 3) is a protein of unknown function which has been implicated in nervous system development through gene knockout studies. We demonstrate here that mice lacking the Tulp3 gene develop abnormalities of both the neural tube and limbs consistent with improper regulation of Shh signaling. Tulp3,/, embryos show expansion of Shh target gene expression and display a ventralization of neural progenitor cells in the caudal neural tube. We further show that Tulp3,/,/Shh,/, compound mutant embryos resemble Tulp3 mutants, and express Shh target genes in the neural tube and limbs which are not expressed in Shh,/, embryos. This work uncovers a novel role for Tulp3 as a negative regulatory factor in the Hh pathway. Developmental Dynamics 238:1140,1149, 2009. © 2009 Wiley-Liss, Inc. [source] Neurotrophin-3 signaling in mammalian Merkel cell developmentDEVELOPMENTAL DYNAMICS, Issue 4 2003Viktor Szeder Abstract Merkel cells are sensory cells of neural crest origin. Because little is known about the mechanisms that direct their differentiation, we have investigated the potential role of a candidate regulatory factor, neurotrophin-3 (NT-3). At embryonic day 16.5 (E 16.5), neither NT-3 nor its primary receptors, TrkC and p75NTR are expressed by Merkel cells in the murine whisker. At the time of birth, however, Merkel cells are immunoreactive for NT-3, TrkC and p75NTR. In TrkC null and NT-3 null mice, Merkel cells differentiate initially, but undergo apoptosis perinatally. These results show that NT-3 signaling is not required for the differentiation of Merkel cells, but that it is essential for their postnatal survival. Developmental Dynamics 228:623,629, 2003. © 2003 Wiley-Liss, Inc. [source] Transcriptional control of the pvdS iron starvation sigma factor gene by the master regulator of sulfur metabolism CysB in Pseudomonas aeruginosaENVIRONMENTAL MICROBIOLOGY, Issue 6 2010Francesco Imperi Summary In the Gram-negative pathogen Pseudomonas aeruginosa, the alternative sigma factor PvdS acts as a key regulator of the response to iron starvation. PvdS also controls P. aeruginosa virulence, as it drives the expression of a large set of genes primarily implicated in biogenesis and transport of the pyoverdine siderophore and synthesis of extracellular factors, such as protease PrpL and exotoxin A. Besides the ferric uptake regulatory protein Fur, which shuts off pvdS transcription under iron-replete conditions, no additional regulatory factor(s) controlling the pvdS promoter activity have been characterized so far. Here, we used the promoter region of pvdS as bait to tentatively capture, by DNA-protein affinity purification, P. aeruginosa proteins that are able to bind specifically to the pvdS promoter. This led to the identification and functional characterization of the LysR-like transcription factor CysB as a novel regulator of pvdS transcription. The CysB protein directly binds to the pvdS promoter in vitro and acts as a positive regulator of PvdS expression in vivo. The absence of a functional CysB protein results in about 50% reduction of expression of PvdS-dependent virulence phenotypes. Given the role of CysB as master regulator of sulfur metabolism, our findings establish a novel molecular link between the iron and sulfur regulons in P. aeruginosa. [source] The IFN regulatory factor 7-dependent type I IFN response is not essential for early resistance against murine cytomegalovirus infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2009Christian Steinberg Abstract IFN regulatory factor 7 (IRF7) has been described as the master regulator of type I IFN responses and has been shown to be critical for innate antiviral immunity in vivo. In addition to type I IFN, NK cell responses are involved in the control of viral replication during acute viral infection. To investigate the role of IRF7 in the context of a viral infection that induces a strong NK cell response, the murine cytomegalovirus (MCMV) infection model was used. WT, IRF7-deficient and IRF3/IRF7-double deficient mice were infected with MCMV. The systemic IFN-, response to MCMV was entirely dependent on IRF7, but independent of IRF3. However, peak IFN-, production during MCMV infection was not affected by the lack of IRF7 or both IRF7 and IRF3. Despite the complete lack of IFN-, production IRF7- and IRF3/IRF7-deficient mice were surprisingly efficient in controlling MCMV replication and were only modestly more susceptible to MCMV infection than WT mice. NK cell cytotoxicity was unimpaired and NK cell IFN-, production was enhanced in IRF7-deficient mice correlating with increased levels of bioactive IL-12. Owing to these compensatory mechanisms IRF7-dependent antiviral immune responses were not essential for resistance against acute MCMV infection in vivo. [source] IFN regulatory factor (IRF) 3/7-dependent and -independent gene induction by mammalian DNA that escapes degradationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2008Yasutaka Okabe Abstract DNase II in macrophages cleaves the DNA of engulfed apoptotic cells and of nuclei expelled from erythroid precursor cells. Macrophages in DNase II-deficient mice accumulate undigested DNA and constitutively produce IFN-, as well as TNF-,. The IFN-, causes severe anemia in the DNase II,/, embryos, which die prenatally. On the other hand, when the DNase II gene is inactivated postnatally, mice develop polyarthritis owing to the TNF-, produced by macrophages. Here, we showed that the IFN-, gene activation in DNase II,/, mice is dependent on IFN regulatory factor (IRF) 3 and 7. Accordingly, DNase II,/,IRF3,/,IRF7,/, mice do not suffer from anemia, but they still produce TNF-,, and age-dependently develop chronic polyarthritis. A microarray analysis of the gene expression in the fetal liver revealed a set of genes that is induced in DNase II,/, mice in an IRF3/IRF7-dependent manner, and another set that is induced independent of these factors. These results indicate that the mammalian chromosomal DNA that accumulates in macrophages due to inefficient degradation activates genes in both IRF3/IRF7-dependent and -independent manners. [source] Revisiting the specificity of the MHC class,II transactivator CIITA in vivoEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2006Abstract CIITA is a master regulatory factor for the expression of MHC class,II (MHC-II) and accessory genes involved in Ag presentation. It has recently been suggested that CIITA also regulates numerous other genes having diverse functions within and outside the immune system. To determine whether these genes are indeed relevant targets of CIITA in vivo, we studied their expression in CIITA-transgenic and CIITA-deficient mice. In contrast to the decisive control of MHC-II and related genes by CIITA, nine putative non-MHC target genes (Eif3s2, Kpna6, Tap1, Yars, Col1a2, Ctse, Ptprr, Tnfsf6 and Plxna1) were found to be CIITA independent in all cell types examined. Two other target genes, encoding IL-4 and IFN-,, were indeed found to be up- and down-regulated, respectively, in CIITA-transgenic CD4+ T,cells. However, there was no correlation between MHC-II expression and this Th2 bias at the level of individual transgenic T,cells, indicating an indirect control by CIITA. These results show that MHC-II-restricted Ag presentation, and its indirect influences on T,cells, remains the only pathway under direct control by CIITA in vivo. They also imply that precisely regulated MHC-II expression is essential for maintaining a proper Th1-Th2 balance. [source] Viral infection and Toll-like receptor agonists induce a differential expression of type,I and , interferons in human plasmacytoid and monocyte-derived dendritic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2004Eliana Abstract In humans, the type,I interferon (IFN) family consists of 13 IFN-, subtypes, IFN-, and IFN-o the newly discovered IFN-like family consists of IFN-,1, -,2 and -,3. We have investigated the expression of type,I and , IFN genes following virus infections or Toll-like receptor (TLR) triggering in monocyte-derived DC (MDDC) and plasmacytoid DC (pDC). We found thatall IFN-,, -,, -o and -, subtypes are expressed in influenza-virus-infected MDDC or pDC. Conversely, differential type,I IFN gene transcription was induced in MDDC and pDC stimulated by specific TLR agonists. TLR-9 stimulation by CpG DNA induced the expression of all IFN-,, -,, -o and -, subtypes in pDC, whereas TLR-4 stimulation by LPS, or TLR-3 stimulation bypoly I:C, induced only IFN-, and IFN-, gene expression in MDDC. The expression pattern of IFN regulatory factor (IRF)-5 and IRF-7 in MDDC and pDC was also determined. IRF-5 was constitutively expressed in the two DC subsets whereas IRF-7 was constitutive in pDC but its expression was induced along MDDC maturation. Overall, our data indicate that the coordinated expression of IFN-, with IFN-, would be of crucial importance for the maturation of DC. [source] N-terminal destruction signals lead to rapid degradation of the major histocompatibility complex class II transactivator CIITAEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2003Felix Schnappauf Abstract Major histocompatibility complex (MHC) class II molecules play an essential role for the cellular immune response by presenting peptide antigens to CD4+ T cells. MHC class II molecules and genes show a highly complex expression pattern, which is orchestrated through a master regulatory factor, called CIITA (class II transactivator). CIITA controls MHC class II expression not only qualitatively, but also quantitatively, and has therefore a direct influence on the CD4 T cell-dependent immune response. CIITA is itself tightly regulated not only on the transcriptional level, but as we show here also on the protein level. CIITA is subjected to a very rapid protein turnover and shows a half-life of about 30,min. Inhibition of degradation by proteasome inhibitors and the identification of ubiquitylated CIITA intermediates indicate that the degradation of CIITA is mediated by the ubiquitin-proteasome system. We identified two regions mediating degradation within the N-terminal domain of CIITA. N-terminal fusions or deletions stabilized CIITA, indicating that the N termini contribute to degradation. Several non-functional CIITA mutants are partially stabilized, but we provide evidence that transcriptional activity of CIITA is not directly linked to degradation. [source] Serotonin may stimulate granule cell proliferation in the adult hippocampus, as observed in rats grafted with foetal raphe neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2000Jean Michel Brezun Abstract The long-term effects of hippocampal serotonergic denervation and reinnervation by foetal raphe tissue were examined in the dentate gyrus where neurons are continously born in the adult. Complete lesion of serotonin neurons following injections of 5,7-dihydroxytryptamine in the dorsal and medial raphe nuclei produced long-term decreases in the number of newly generated granule cells identified with 5-Bromo-2,-deoxyuridine (BrdU) and the polysialylated form of neural cell adhesion molecule (PSA-NCAM) immunostaining, as observed in 2-month-survival rats. The raphe grafts, but not the control grafts of embryonic spinal tissue, reversed the postlesion-induced decreases in the density of BrdU- and PSA-NCAM-labelled cells detected in the granule layer. Inhibition of serotonin synthesis in animals with raphe grafts reversed back to lesion-induced changes in granule cell proliferation. Furthermore, extensive serotonergic reinnervation of the dentate gyrus in the area proximal to the raphe graft could be associated with supranormal density of BrdU-labelled cells. These results indicate that serotonin may be considered a positive regulatory factor of adult granule cell proliferation. Finally, the lack of effect of embryonic nonserotonergic tissue grafted to serotonin-deprived rats suggests that neurotrophic factors may not be involved in the effects of serotonin on adult neurogenesis. [source] Immune response modifiers , mode of actionEXPERIMENTAL DERMATOLOGY, Issue 5 2006Meinhard Schiller Abstract:, The innate immune system governs the interconnecting pathways of microbial recognition, inflammation, microbial clearance, and cell death. A family of evolutionarily conserved receptors, known as the Toll-like receptors (TLRs), is crucial in early host defense against invading pathogens. Upon TLR stimulation, nuclear factor-,B activation and the interferon (IFN)-regulatory factor 3 pathway initiate production of pro-inflammatory cytokines, such as interleukin-1 and tumor necrosis factor-,, and production of type I IFNs (IFN-, and IFN-,), respectively. The innate immunity thereby offers diverse targets for highly selective therapeutics, such as small molecular synthetic compounds that modify innate immune responses. The notion that activation of the innate immune system is a prerequisite for the induction of acquired immunity raised interest in these immune response modifiers as potential therapeutics for viral infections and various tumors. A scenario of dermal events following skin cancer treatment with imiquimod presumably comprises (i) an initial low amount of pro-inflammatory cytokine secretion by macrophages and dermal dendritic cells (DCs), thereby (ii) attracting an increasing number type I IFN-producing plasmacytoid DCs (pDCs) from the blood; (iii) Langerhans cells migrate into draining lymph nodes, leading to an increased presentation of tumor antigen in the draining lymph node, and (iv) consequently an increased generation of tumor-specific T cells and finally (v) an accumulation of tumoricidal effector cells in the treated skin area. The induction of predominately T helper (Th)1-type cytokine profiles by TLR agonists such as imiquimod might have further benefits by shifting the dominant Th2-type response in atopic diseases such as asthma and atopic dermatitis to a more potent Th1 response. [source] Mechanism for transcriptional synergy between interferon regulatory factor (IRF)-3 and IRF-7 in activation of the interferon-, gene promoterFEBS JOURNAL, Issue 18 2004Hongmei Yang The interferon-, promoter has been studied extensively as a model system for combinatorial transcriptional regulation. In virus-infected cells the transcription factors ATF-2, c-Jun, interferon regulatory factor (IRF)-3, IRF-7 and NF-,B, and the coactivators p300/CBP play critical roles in the activation of this and other promoters. It remains unclear, however, why most other combinations of AP-1, IRF and Rel proteins fail to activate the interferon-, gene. Here we have explored how different IRFs may cooperate with other factors to activate transcription. First we showed in undifferentiated embryonic carcinoma cells that ectopic expression of either IRF-3 or IRF-7, but not IRF-1, was sufficient to allow virus-dependent activation of the interferon-, promoter. Moreover, the activity of IRF-3 and IRF-7 was strongly affected by promoter context, with IRF-7 preferentially being recruited to the natural interferon-, promoter. We fully reconstituted activation of this promoter in insect cells. Maximal synergy required IRF-3 and IRF-7 but not IRF-1, and was strongly dependent on the presence of p300/CBP, even when these coactivators only modestly affected the activity of each factor by itself. These results suggest that specificity in activation of the interferon-, gene depends on a unique promoter context and on the role played by coactivators as architectural factors. [source] Transcriptional activity of interferon regulatory factor (IRF)-3 depends on multiple protein,protein interactionsFEBS JOURNAL, Issue 24 2002Hongmei Yang Virus infection results in the activation of a set of cellular genes involved in host antiviral defense. IRF-3 has been identified as a critical transcription factor in this process. The activation mechanism of IRF-3 is not fully elucidated, yet it involves a conformational change triggered by the virus-dependent phosphorylation of its C-terminus. This conformational change leads to nuclear accumulation, DNA binding and transcriptional transactivation. Here we show that two distinct sets of Ser/Thr residues of IRF-3, on phosphorylation, synergize functionally to achieve maximal activation. Remarkably, we find that activated IRF-3 lacks transcriptional activity, but activates transcription entirely through the recruitment of the p300/CBP coactivators. Moreover, we show that two separate domains of IRF-3 interact with several distinct regions of p300/CBP. Interference with any of these interactions leads to a complete loss of transcriptional activity, suggesting that a bivalent interaction is essential for coactivator recruitment by IRF-3. [source] Functional analysis of the rat bile salt export pump gene promoterFEBS JOURNAL, Issue 14 2002Regulation by bile acids, drugs, endogenous compounds The 5, flanking region of the bile salt export pump (Bsep) gene was systematically analysed to provide the basis for understanding the mechanisms which regulate Bsep transcription. In addition substrates and drugs were investigated for their ability to alter Bsep promoter activity. Bsep promoter function was restricted to hepatocyte derived HepG2 cells. The 5, deletional analysis revealed a biphasic shape of reporter gene activities, indicating a suppressive element between nucleotides ,800 and ,512. Two consensus sites for the farnesoid X receptor (FXR) were located at nucleotides ,473 and ,64. The latter was characterized as functionally active in bile acid-mediated feed-back regulation of Bsep transcription. Bsep promoter activity was reduced by rifampin and ,-estradiol. The anti-estrogen tamoxifen stimulated promoter activity. Dexamethasone, hydrocortisone and phenobarbital had no effect on Bsep promoter activity. In conclusion, the data suggest that transcriptional regulation of the Bsep gene can be modulated by a number of endogenous compounds and xenobiotics. FXR was a major regulatory factor, mediating bile acid feed-back stimulation of Bsep transcription. [source] Complementation of NADPH oxidase in p67-phox-deficient CGD patientsFEBS JOURNAL, Issue 4 2000p67-phox/p40-phox interaction Chronic granulomatous disease (CGD) is due to a functional defect of the O2, generating NADPH oxidase of phagocytes. Epstein,Barr-virus-immortalized B lymphocytes express all the constituents of oxidase with activity 100 times less than that of neutrophils. As in neutrophils, oxidase activity of Epstein,Barr-virus-immortalized B lymphocytes was shown to be defective in the different forms of CGD; these cells were used as a model for the complementation studies of two p67-phox-deficient CGD patients. Reconstitution of oxidase activity was performed in vitro by using a heterologous cell-free assay consisting of membrane-suspended or solubilized and purified cytochrome b558 that was associated with cytosol or with the isolated cytosolic-activating factors (p67-phox, p47-phox, p40-phox) from healthy or CGD patients. In p67-phox-deficient CGD patients, two cytosolic factors are deficient or missing: p67-phox and p40-phox. Not more than 20% of oxidase activity was recovered by complementing the cytosol of p67-phox-deficient patients with recombinant p67-phox. On the contrary, a complete restoration of oxidase activity was observed when, instead of cytosol, the cytosolic factors were added in the cell-free assay after isolation in combination with cytochrome b558 purified from neutrophil membrane. Moreover, the simultaneous addition of recombinant p67-phox and recombinant p40-phox reversed the previous complementation in a p40-phox dose-dependent process. These results suggest that in the reconstitution of oxidase activity, p67-phox is the limiting factor; the efficiency of complementation depends on the membrane tissue and the cytosolic environment. In vitro, the transition from the resting to the activated state of oxidase, which results from assembling, requires the dissociation of p40-phox from p67-phox for efficient oxidase activity. In the process, p40-phox could function as a negative regulatory factor and stabilize the resting state. [source] Trophic interactions in the methanogenic microbial community of low-temperature terrestrial ecosystemsFEMS MICROBIOLOGY ECOLOGY, Issue 1 2005O.R. Kotsyurbenko Abstract The formation of methane in various ecosystems is due to the functioning of an anaerobic community, which combines trophically different groups of microorganisms. The methanogenic microbial community is a complex biological system, which responds to low temperatures by changes in its trophic structure resulting in redistributing matter flows. The enhanced activity of homoacetogenic bacteria at low temperature plays a significant role in this redistribution. Due to their relatively high growth rates and metabolic versatility, homoacetogens can successfully compete with fermenting bacteria and hydrogenotrophic methanogenic archaea for common substrates. The concentration of hydrogen is an important regulatory factor in the psychroactive methanogenic community. At low temperature methanogenic archaea possessing a higher affinity for hydrogen than homoacetogens provide for interspecies H2 transport in syntrophic reactions of fatty acid decomposition. The formation of a balanced community at low temperature is a longtime process. Cold terrestrial ecosystems are dominated by psychroactive (psychrotolerant) microorganisms, which can grow over a wide range of ambient temperatures. [source] Genetic variants in IRF6 and the risk of facial clefts: single-marker and haplotype-based analyses in a population-based case-control study of facial clefts in NorwayGENETIC EPIDEMIOLOGY, Issue 5 2008Astanand Jugessur Abstract Mutations in the gene encoding interferon regulatory factor 6 (IRF6) underlie a common form of syndromic clefting known as Van der Woude syndrome. Lip pits and missing teeth are the only additional features distinguishing the syndrome from isolated clefts. Van der Woude syndrome, therefore, provides an excellent model for studying the isolated forms of clefting. From a population-based case-control study of facial clefts in Norway (1996,2001), we selected 377 cleft lip with or without cleft palate (CL/P), 196 cleft palate only (CPO), and 763 control infant-parent triads for analysis. We genotyped six single nucleotide polymorphisms within the IRF6 locus and estimated the relative risks (RR) conferred on the child by alleles and haplotypes of the child and of the mother. On the whole, there were strong statistical associations with CL/P but not CPO in our data. In single-marker analyses, mothers with a double-dose of the ,a'-allele at rs4844880 had an increased risk of having a child with CL/P (RR=1.85, 95% confidence interval: 1.04,3.25; P=0.036). An RR of 0.38 (95% confidence interval: 0.16,0.92; P=0.031) was obtained when the child carried a single-dose of the ,a'-allele at rs2235371 (the p.V274I polymorphism). The P -value for the overall test was <0.001. In haplotype analyses, several of the fetal and maternal haplotype relative risks were statistically significant individually but were not strong enough to show up on the overall test (P=0.113). Taken together, these findings further support a role for IRF6 variants in clefting of the lip and provide specific risk estimates in a Norwegian population. Genet. Epidemiol. 2008. © 2008 Wiley-Liss, Inc. [source] The TLR3 ligand polyI:C downregulates connexin 43 expression and function in astrocytes by a mechanism involving the NF-,B and PI3 kinase pathwaysGLIA, Issue 8 2006Yongmei Zhao Abstract Toll-like receptor 3 (TLR3) is a component of the innate immune response that responds to dsRNA viruses and virus replication intermediates. In this study we show that activation of astrocytes with the dsRNA mimetic polyinosinic-cytidylic acid (pI:C) results in loss of expression of connexin43 (Cx43) mRNA and protein while upregulating the expression of the ionotropic P2 receptor P2X4R. Analysis of the signaling pathways involved failed to demonstrate a role for the p38 MAP kinase, ERK, or JNK signaling pathways whereas an inhibitor of the PI3 kinase/Akt pathway effectively blocked the action of pI:C. Using adenoviral vectors containing a super-repressor of NF-,B (NF-,B SR) construct or a dominant negative interferon regulatory factor 3 (dnIRF3) construct showed that inhibition of both transcription factors also blocked the effects of pI:C. To explore the functional consequences of pI:C activation we used a pore-forming assay for P2X4R activity and a scrape loading assay for gap junction intercellular communication (GJIC). No pore-forming activity consistent with functional P2X4R expression was detected in either control or activated astrocytes. In contrast, robust Lucifer yellow transfer indicative of GJIC was detected in resting cells that was lost following pI:C activation. The dnIRF3 construct failed to restore GJIC whereas the NF-,B SR or the NF-,B inhibitor BAY11-7082 and the PI3K inhibitor LY294002 all significantly reversed the effect of pI:C on GJ connectivity. We conclude that activation of the innate immune response in astrocytes is associated with functional loss of GJIC through a pathway involving NF-,B and PI3 kinase. © 2006 Wiley-Liss, Inc. [source] Hepatitis C virus escape from the interferon regulatory factor 3 pathway by a passive and active evasion strategy,HEPATOLOGY, Issue 5 2007Marco Binder Hepatitis C virus (HCV) has been known to replicate with extremely varying efficiencies in different host cells, even within different populations of a single human hepatoma cell line, termed Huh-7. Several reports have implicated the retinoic-acid inducible gene I (RIG-I)/ interferon regulatory factor 3 (IRF-3) pathway of the innate antiviral response with differences in host cell permissiveness to HCV. To investigate the general impact of the IRF-3 response onto HCV replication in cell culture, we generated an ample array of stable Huh-7 cell lines with altered IRF-3 responsiveness. Neither blocking IRF-3 activation in various host cells by expression of dominant negative RIG-I or HCV NS3/4A protease nor reconstitution of RIG-I signaling in Huh7.5, a cell clone known to be defective in this pathway, had any impact on HCV replication. Only by overexpressing constitutively active RIG-I or the signaling adaptor Cardif (also known as interferon-beta promoter stimulator 1, mitochondrial anti-viral signaling protein, or virus-induced signaling adaptor), both leading to a stimulation of the IRF-3 pathway in the absence of inducers, was HCV replication significantly inhibited. We therefore assessed the extent of RIG-I, dependent IRF-3 activation by different species of RNA, including full-length HCV genomes and HCV RNA duplexes, and observed strong induction only in response to double-stranded RNAs. Conclusion: Based on these findings, we propose a refined model of innate immune escape by HCV involving limited initial induction and stringent subsequent control of the IRF-3 response. (HEPATOLOGY 2007.) [source] Biological role of NHERF1 protein expression in breast cancerHISTOPATHOLOGY, Issue 5 2009Anita Mangia Aims:, To determine the role of Na+/H+ exchanger regulatory factor (NHERF1) in breast cancerogenesis and progression. Methods and results:, NHERF1 expression was examined in normal tissue, ductal carcinoma in situ (DCIS), invasive carcinoma (IBC), synchronous metastatic lymph node and metachronous distant metastases of a retrospective series of breast cancers. Fifty-one IBC, 42 DCIS and normal tissues were examined immunohistochemically, and the colocalization between NHERF1 and HER2/neu was studied by immunofluorescence. NHERF1 showed a different localization and pattern of expression in the different compartments of the breast. The mean value of cytoplasmic NHERF1 expression in paired samples was significantly higher in DCIS, IBC, distant metastases and metastatic lymph nodes with respect to normal tissues. Moreover, in metastatic lymph nodes NHERF1 was exclusively cytoplasmic. In the membrane NHERF1 was colocalized with overexpressed HER2/neu in DCIS, IBC and distant metastases. Conclusions:, Breast cancerogenesis is characterized by increased cytoplasmic expression of NHERF1 as the tumour progresses, suggesting a role in this process. The switch from apical membranous to cytoplasmic expression is compatible with a dual role for NHERF1 as a tumour suppressor or tumour promoter dependent on its subcellular localization. [source] Transcriptional regulation of aquaporin 3 by insulinJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2007Shota Higuchi Abstract In the current study, we identified a regulatory factor for the transcription of aquaporin 3 (AQP3) whose expression is repressed by insulin. We constructed a luciferase reporter vector containing bp ,1382 to ,12 of the 5,-flanking region of the AQP3 gene for a reporter gene assay and observed that luciferase activity in transfectants with the plasmid decreased on treatment with insulin. Serial deletion constructs revealed two regions responsible for the insulin-mediated repression, one between bps ,1382 and ,780, and the other between bps ,404 and ,82. mRNA expression of forkhead box a2 (Foxa2), the binding site of which was located between bps ,1382 and ,780, was found to decrease on treatment with insulin. A mutant reporter plasmid with an altered Foxa2-binding site and siRNA for the Foxa2 sequence counteracted the insulin-mediated repression of AQP3 transcription. These results suggest that Foxa2 is one of the transcriptional regulators for AQP3 gene expression regulated by insulin. J. Cell. Biochem. 102: 1051,1058, 2007. © 2007 Wiley-Liss, Inc. [source] Interferon regulatory factor-1 acts as a powerful adjuvant in tat DNA based vaccination,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2010Arianna Castaldello Genetic vaccines are safe cost-effective approaches to immunization but DNA immunization is an inefficient process. There is, therefore, a pressing need for adjuvants capable of enhancing the immunogenicity and effectiveness of these vaccines. This is particularly important for diseases for which successful vaccines are still lacking, such as cancer and infectious diseases including HIV-1/AIDS. Here we report an approach to enhance the immunogenicity of DNA vaccines involving the use of transcription factors of the Interferon regulatory factor (IRF) family, specifically IRF-1, IRF-3, and IRF-7 using the tat gene as model antigen. Balb/c mice were immunized by three intramuscular inoculations, using a DNA prime-protein boost protocol, with a DNA encoding tat of HIV-1 and the indicated IRFs and immune responses were compared to those induced by vaccination with tat DNA alone. In vivo administration of plasmid DNA encoding IRF-1, or a mutated version of IRF-1 deleted of the DNA-binding domain, enhanced Tat-specific immune responses and shifted them towards a predominant T helper 1-type immune response with increased IFN-, production and cytotoxic T lymphocytes responses. Conversely, the use of IRF-3 or IRF-7 did not affect the tat -induced responses. These findings define IRF-1 and its mutated form as efficacious T helper 1-inducing adjuvants in the context of tat- based vaccination and also providing a new promising candidate for genetic vaccine development. J. Cell. Physiol. 224: 702,709, 2010. © 2010 Wiley-Liss, Inc. [source] Estrogen produced in cultured hippocampal neurons is a functional regulator of a GABAergic machineryJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Takamitsu Ikeda Abstract Accumulating evidence suggests that estrogen is produced locally by the neurons in the brain. We observed that a 48-hr treatment with the estrogen receptor antagonists ICI 182780 and tamoxifen decreased the level of glutamate decarboxylase (GAD)-65, a rate-limiting ,-aminobutyric acid (GABA)-synthesizing enzyme, in a dissociated hippocampal neuronal culture. Aromatase is an essential enzyme for estrogen biosynthesis. Treatment with an aromatase inhibitor decreased the GAD 65 level, indicating that estrogen biogenesis functions to maintain the level of this enzyme for GABAergic neurotransmission. Furthermore, insofar as the effect of ICI 182780 was observed equivalently in the presence of either brain-derived neurotrophic factor (BDNF) or BDNF-receptor inhibitor K252a, estrogen probably regulates GAD level independently of brain-derived neurotrophic factor (BDNF). Thus, estrogen produced by neurons is considered to be an intrinsic regulatory factor for neuronal networks that maintain GABAergic neurotransmission. © 2006 Wiley-Liss, Inc. [source] Clinical application of an enzyme immunoassay for cholecystokinin-like immunoreactive substance for determination of the human plasma levels: the effect of metoclopramide on gastrointestinal peptides and stress-related hormonesJOURNAL OF PEPTIDE SCIENCE, Issue 5 2006Fumihiko Katagiri Abstract Metoclopramide, a prokinetic drug, is widely used to treat vomiting and nausea. Delayed gastric emptying and continual stress are considered important factors, among others, that induce nausea and vomiting. One gastrointestinal motility regulatory factor has been assumed to be the induction of changes in the levels of peptides such as gastrin, somatostatin, motilin, and cholecystokinin (CCK) in plasma. In contrast, adrenocorticotropic hormone (ACTH) and cortisol are used as indicators of stress. Here, we studied the effects of metoclopramide on human plasma gastrin-, somatostatin-, motilin-, and CCK-like immunoreactive substances (ISs) and ACTH-IS and cortisol under stress conditions using repetitive blood sampling in healthy subjects. Metoclopramide hydrochloride at a dose of 30 mg or placebo was orally administered to five healthy male volunteers. Blood samples were taken before and 20, 40, 60, 90, 120, 180, and 240 min after administration, subject to extracting procedures, and submitted to a highly sensitive enzyme immunoassay system. A single administration of metoclopramide caused significant increases in plasma somatostatin-IS levels compared with the placebo. Metoclopramide significantly decreased plasma gastrin- and suppressed ACTH-IS and cortisol levels compared with the placebo. We hypothesize that metoclopramide might have an accelerating gastric-emptying effect and a modulatory effect on the hypothalamo-pituitary-adrenal (HPA) axis and the autonomic nervous function. These effects might be beneficial in stress-related diseases, which suggest that this medicine has clinicopharmacological activities. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Melatonin decreases TLR3-mediated inflammatory factor expression via inhibition of NF-,B activation in respiratory syncytial virus-infected RAW264.7 macrophagesJOURNAL OF PINEAL RESEARCH, Issue 1 2008Sheng-Hai Huang Abstract:, Double-stranded (ds) RNA has been identified as a ligand for Toll-like receptor 3 (TLR3). Respiratory syncytial virus (RSV), a single-stranded RNA virus and a major respiratory pathogen and pneumovirus in human infants pathogenesis of which relies on early inflammatory and immune events of the host in response to RSV, could be recognized by TLR3 sensing viral dsRNA produced during replication. The downstream signaling pathway from TLR3 leads to activation of IFN regulatory factor (IRF)-3 and/or NF-,B and subsequent expression of numerous proinflammatory factors. Melatonin (MT) is an effective regulator of the immune system. To determine the molecular mechanisms responsible for the suppressive effect of MT on RSV infection, we analyzed signaling molecules involved in the TLR3-mediated activation of inflammatory factors in macrophages infected with RSV and the modulatory role of MT on these mediators. We report that RSV infection of RAW264.7 macrophages time-dependently stimulate the rapid activation of TLR3 and NF-,B, as well as subsequent NF-,B-dependent gene expression such as those encoding TNF-, and inducible nitric oxide synthase. Moreover, we demonstrate that MT decreased TLR3-mediated downstream gene expression in RSV-infected macrophages in a dose- and time-dependent manner, and that MT inhibition of NF-,B activity seemed to be the key event required to explain the reduction in inflammatory gene expression caused by MT. But MT did not influence TLR3 at either the protein or mRNA level or MyD88 transcription. These results could be related to the beneficial immunoregulatory role of MT in RSV-infected macrophages and address the possible therapeutic potential of this indoleamine in human RSV diseases. [source] | |||||||||||||||||||||||||||||||||||||