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Differential Regulation (differential + regulation)
Selected AbstractsDIFFERENTIAL REGULATION OF ANGIOTENSIN II RECEPTORS DURING RENAL INJURY AND COMPENSATORY HYPERTROPHY IN THE RATCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2005Emma Joly SUMMARY 1.,The renin-angiotensin system may be involved in the compensatory adaptations occurring after the reduction of renal mass and during the consecutive changes leading to chronic renal failure. We therefore investigated the regulation of angiotensin II receptors in two models of renal hypertrophy in the rat: hypertrophy following uninephrectomy (UNx) or subtotal nephrectomy (STNx). The level of angiotensin type 1 (AT1A -R and AT1B -R) and type 2 (AT2 -R) receptor mRNA was quantified by competitive reverse transcription-polymerase chain reaction (RT-PCR) in specific renal zones and the intrarenal distribution of angiotensin II receptors was analysed by immunohistochemistry. 2.,In the UNx rats, AT1 -R mRNA expression was not modified in the cortex or in the inner stripe of the outer medulla of the residual kidney at any time after the surgery (1, 4 and 12 weeks). In contrast, AT1 -R mRNA expression was significantly reduced in these zones in STNx rats (,33% and ,40%, respectively). This downregulation was organ-specific, as AT1 -R mRNA levels were not modified in the liver. The proportions of AT1 -R subtype (AT1A and AT1B) mRNA were unchanged by UNx or STNx. Very low levels of AT2 -R mRNA were found in the cortex of all groups. Immunostaining revealed a similar localization of AT1 -R in mesangial cells, proximal tubule, basolateral membrane of thick ascending limb, in both models of hypertrophy. AT1 -R labelling was also detected in the apical membrane of intercalated cells of cortical collecting ducts. 3.,This differential mRNA expression of angiotensin II receptors during compensatory hypertrophy and renal injury suggests that the development of renal hypertrophy is independent of AT1 -R and AT2 -R gene expression levels. [source] Differential Regulation of Five Pht1 Phosphate Transporters from Maize (Zea mays L.)PLANT BIOLOGY, Issue 2 2006R. Nagy Abstract: Maize is one of the most important crops in the developing world, where adverse soil conditions and low fertilizer input are the two main constraints for stable food supply. Understanding the molecular and biochemical mechanisms involved in nutrient uptake is expected to support the development of future breeding strategies aimed at improving maize productivity on infertile soils. Phosphorus is the least mobile macronutrient in the soils and it is often limiting plant growth. In this work, five genes encoding Pht1 phosphate transporters which contribute to phosphate uptake and allocation in maize were identified. In phosphate-starved plants, transcripts of most of the five transporters were present in roots and leaves. Independent of the phosphate supply, expression of two genes was predominant in pollen or in roots colonized by symbiotic mycorrhizal fungi, respectively. Interestingly, high transcript levels of the mycorrhiza-inducible gene were also detectable in leaves of phosphate-starved plants. Thus, differential expression of Pht1 phosphate transporters in maize suggests involvement of the encoded proteins in diverse processes, including phosphate uptake from soil and transport at the symbiotic interface in mycorrhizas, phosphate (re)translocation in the shoot, and phosphate uptake during pollen tube growth. [source] Differential regulation of GDF-5 and FGF-2/4 by immobilisation in ovo exposes distinct roles in joint formation,DEVELOPMENTAL DYNAMICS, Issue 3 2006E. Kavanagh Abstract Members of the fibroblast growth factor (FGF) family and growth and differentiation factor 5 (GDF-5) have been implicated in joint specification, but their roles in subsequent cavity formation are not defined. Cavity formation (cavitation) depends upon limb movement in embryonic chicks and factors involved in joint formation are often identified by their expression at the joint-line. We have sought support for the roles of FGF-2, FGF-4, and GDF-5 in cavitation by defining expression patterns, immunohistochemically, during joint formation and establishing whether these are modified by in ovo immobilisation. We found that FGF-2 exhibited low level nuclear expression in chondrocytes and fibrocartilage cells close to presumptive joints, but showed significantly higher expression levels in cells at, and directly bordering, the forming joint cavity. This high-level joint line FGF-2 expression was selectively diminished in immobilised limbs. In contrast, we show that FGF-4 does not exhibit differential joint-line expression and was unaffected by immobilisation. GDF-5 protein also failed to show joint-line selective labelling, and although immobilisation induced a cartilaginous fusion across presumptive joints, it did not affect cellular GDF-5 expression patterns. Examining changes in GDF-5 expression in response to a direct mechanical strain stimulus in primary embryonic chick articular surface (AS) cells in vitro discloses only small mechanically-induced reductions in GDF-5 expression, suggesting that GDF-5 does not exert a direct positive contribution to the mechano-dependent joint cavitation process. This notion was supported by retroviral overexpression of UDPGD, a characteristic factor involved in hyaluronan (HA) accumulation at presumptive joint lines, which was also found to produce small decreases in AS cell GDF-5 expression. These findings support a direct mechano-dependent role for FGF-2, but not FGF-4, in the cavitation process and indicate that GDF-5 is likely to influence chondrogenesis positively without contributing directly to joint cavity formation. Developmental Dynamics 235:826,834, 2006. © 2006 Wiley-Liss, Inc. [source] Differential regulation of trkA and p75 in noradrenergic pelvic autonomic ganglion cells after deafferentation of their cholinergic neighboursEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2001Janet R. Keast Abstract In rats, following lesion of lumbar or sacral preganglionic axons, many pelvic ganglion cells undergo axogenesis to form baskets of terminals around select populations of nearby ganglion cells. The aim of the current study was to address mechanisms underlying initiation of this sprouting, focusing on a possible role for nerve growth factor (NGF). Immunohistochemical localization of NGF receptors (trkA and p75) showed that virtually all noradrenergic and a minority of cholinergic pelvic neurons expressed both receptors. Terminals immunoreactive for each substance were found in pelvic viscera. In pelvic ganglia, many glial cells expressed p75 but not trkA, and very few lumbar or sacral preganglionic neurons expressed either receptor. Lumbar and/or sacral preganglionic inputs were removed from ganglion cells by cutting the hypogastric, pelvic or both nerves, and tissues analysed 8 days later. Levels of receptor expression in noradrenergic pelvic ganglion cells were estimated by calculating the proportion that were receptor-immunopositive, and quantifying the intensity of trkA or p75 immunofluorescence. No lesion had a significant effect on trkA expression, however, a marked decrease in p75 occurred after cutting pelvic nerves, i.e. after deafferentation of neighbouring cholinergic neurons. These injuries appeared to cause little overall change in glial p75 expression. This study shows that manipulations that trigger sprouting from noradrenergic pelvic neurons cause downregulation of p75 but not trkA. Interestingly, this is occurring while some of their target organs are synthesizing high levels of NGF. This contrasts with other NGF-sensitive cells, in which one or both receptor types are upregulated by increased exposure to the ligand. The current study is also the first to show a change in p75 expression in neurons that are neither deafferented nor axotomized. [source] Differential regulation of the nitric oxide,cGMP pathway exacerbates postischaemic heart injury in stroke-prone hypertensive ratsEXPERIMENTAL PHYSIOLOGY, Issue 1 2007Tetsuji Itoh Using a working perfused heart model, we investigated the hypothesis that alterations in the NO,cGMP pathway may exacerbate postischaemic mechanical dysfunction in the hypertrophied heart. Ischaemia for 25 min followed by reperfusion for 30 min produced marked cardiac mechanical dysfunction in both stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY). Exogenous treatment with S -nitroso- N -acetyl- dl -penicillamine (SNAP), a NO donor, had beneficial effects on the cardiac dysfunction induced by ischaemia,reperfusion (I/R) in the WKY heart, but the cardioprotective effect of SNAP was eliminated by guanylyl cyclase inhibitor. Cardiac cGMP levels were increased by SNAP or ischaemia in WKY. In contrast, in SHRSP hearts, SNAP could not alleviate the cardiac dysfunction caused by I/R. Pre-ischaemia, the cardiac cGMP level was significantly higher in SHRSP than in WKY; however, no significant difference was found after SNAP and ischaemia. The myocardial Ca2+ -dependent NO synthase (NOS) activity increased at the end of ischaemia in WKY. Conversely, the Ca2+ -independent NOS activity and protein levels were upregulated by I/R in the SHRSP myocardium. In the SHRSP hearts, non-selective NOS and selective Ca2+ -independent NOS inhibitors or antioxidant treatment alleviated cardiac dysfunction caused by I/R. Moreover, mRNA expression and Western blotting analysis of cGMP-dependent protein kinase type I showed more deterioration of SHRSP hearts compared with WKY. These results suggest that: (1) the NO-dependent cardioprotective effect is depressed; and (2) overproduction of NO derived from Ca2+ -independent NOS contributes to postischaemic heart injury in the hypertrophied heart of hypertensive status. [source] Differential regulation of amoA and amoB gene copies in Nitrosomonas europaeaFEMS MICROBIOLOGY LETTERS, Issue 2 2000Lisa Y Stein Abstract Nitrosomonas europaea contains two nearly identical copies of the operon, amoCAB, which encodes the ammonia monooxygenase (AMO) enzyme. Cells of N. europaea containing single mutations in either amoA or amoB gene copies were incubated in ammonium both prior to and after exposure to acetylene or light. For each strain, the O2 consumption rates and amounts of AmoA polypeptide, the active site-containing subunit of AMO, produced in each strain were determined. Strains carrying a mutation in either the amoA2 or amoB2 genes responded similarly to wild-type cells, but the strains carrying mutations in the amoA1 or amoB1 genes responded differently from the wild-type, or from each other. These results suggest that the copies of amoA and amoB are differentially regulated upon exposure to different external stimuli. [source] Differential regulation of CaMKII inhibitor , protein expression after exposure to a novel context and during contextual fear memory formationGENES, BRAIN AND BEHAVIOR, Issue 6 2010K. Radwa Understanding of the molecular basis of long-term fear memory (fear LTM) formation provides targets in the treatment of emotional disorders. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is one of the key synaptic molecules involved in fear LTM formation. There are two endogenous inhibitor proteins of CaMKII, CaMKII N, and N,, which can regulate CaMKII activity in vitro. However, the physiological role of these endogenous inhibitors is not known. Here, we have investigated whether CaMKII N, protein expression is regulated after contextual fear conditioning or exposure to a novel context. Using a novel CaMKII N, -specific antibody, CaMKII N, expression was analysed in the naïve mouse brain as well as in the amygdala and hippocampus after conditioning and context exposure. We show that in naïve mouse forebrain CaMKII N, protein is expressed at its highest levels in olfactory bulb, prefrontal and piriform cortices, amygdala and thalamus. The protein is expressed both in dendrites and cell bodies. CaMKII N, expression is rapidly and transiently up-regulated in the hippocampus after context exposure. In the amygdala, its expression is regulated only by contextual fear conditioning and not by exposure to a novel context. In conclusion, we show that CaMKII N, expression is differentially regulated by novelty and contextual fear conditioning, providing further insight into molecular basis of fear LTM. [source] Differential regulation of trophic and proinflammatory microglial effectors is dependent on severity of neuronal injuryGLIA, Issue 3 2008Aaron Y. Lai Abstract Microglial activation has been reported to promote neurotoxicity and also neuroprotective effects. A possible contributor to this dichotomy of responses may be the degree to which proximal neurons are injured. The aim of this study was to determine whether varying the severity of neuronal injury influenced whether microglia were neuroprotective or neurotoxic. We exposed cortical neuronal cultures to varying degrees of hypoxia thereby generating mild (<20% death, 30min hypoxia), moderate (40,60% death, 2 h hypoxia), or severe (>70% death, 6 h hypoxia) injuries. Twenty-four hours after hypoxia, the media from the neuronal cultures was collected and incubated with primary microglial cultures for 24 h. Results showed that the classic microglial proinflammatory mediators including inducible nitric oxide synthase, tumor necrosis factor ,, and interleukin-1-, were upregulated only in response to mild neuronal injuries, while the trophic microglial effectors brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor were upregulated in response to all degrees of neuronal injury. Microglia stimulated with media from damaged neurons were co-cultured with hypoxic neurons. Microglia stimulated by moderate, but not mild or severe damage were neuroprotective in these co-cultures. We also showed that the severity-dependent phenomenon was not related to autocrine microglial signaling and was dependent on the neurotransmitters released by neurons after injury, namely glutamate and adenosine 5,-triphosphate. Together our results show that severity of neuronal injury is an important factor in determining microglial release of "toxic" versus "protective" effectors and the resulting neurotoxicity versus neuroprotection. © 2007 Wiley-Liss, Inc. [source] Differential regulation of TGF-, signal in hepatic stellate cells between acute and chronic rat liver injuryHEPATOLOGY, Issue 1 2002Yoshiya Tahashi During chronic liver injury, transforming growth factor , (TGF-,) plays a prominent role in stimulating liver fibrogenesis by myofibroblast-like cells derived from hepatic stellate cells (HSCs). On the other hand, Smad 7 was recently shown to antagonize the TGF-,,induced activation of signal-transducing Smads (2 and 3). In this study, we investigated the regulatory mechanisms of the TGF-, signals in rat HSCs during acute liver injury and myofibroblasts (MFBs) during chronic liver injury, focusing on the roles of Smad 2 and antagonistic Smad 7. In acute liver injury, HSC-derived TGF-, increased plasminogen activator inhibitor type 1 (PAI-1) and ,2(I) procollagen (COL1A2) transcripts. Smad 2 in HSCs during liver injury and primary cultured HSCs were activated by an autocrine mechanism, because high levels of Smad 2 phosphorylation and induction of PAI-1 transcript by TGF-, were observed in HSCs. Thereafter, Smad 7 induced by TGF-, negatively regulated the Smad 2 action. These results indicated that endogenous TGF,,mediated Smad 7 in HSCs terminated the fibrotic signals mediated by signal-transducing Smads, and might be involved in the transient response to autocrine TGF-, signal after acute liver injury. By contrast, Smad 7 was not induced by the autocrine TGF-, signal, and constitutive Smad 2 activation was observed in MFBs throughout chronic liver injury, although Smad 7 could inhibit the TGF-, signal requiring Smad 2 phosphorylation by activated TGF-, receptor in cultured MFBs. This constitutive phosphorylation of Smad 2 by endogenous TGF-, under a low level of Smad 7 could be involved in the progression of liver fibrosis. [source] Differential regulation of SOCS-1 signalling in B and T lymphocytes by hepatitis C virus core proteinIMMUNOLOGY, Issue 2 2008Zhi Qiang Yao Summary Hepatitis C virus (HCV) infection is characterized by a strong propensity toward chronicity, autoimmune phenomena and lymphomagenesis, supporting a role for lymphocyte dysregulation during persistent viral infection. We have shown that HCV core protein inhibits T-cell functions through interaction with a complement receptor, gC1qR. Here, we further report that B cells also express gC1qR that can be bound by HCV core protein. Importantly, using flow cytometry, we demonstrated differential regulation of B and T lymphocytes by the HCV core,gC1qR interaction, with down-regulation of CD69 activation in T cells but up-regulation of CD69 activation and cell proliferation in B cells. HCV core treatment led to decreased interferon-, production in CD8+ T cells but to increased immunoglobulin M and immunoglobulin G production as well as cell surface expression of costimulatory and chemokine receptors, including CD86 (B7-2), CD154 (CD40L) and CD195 (CCR5), in CD20+ B cells. Finally, we showed down-regulation of suppressor of cytokine signalling-1 (SOCS-1) using real-time reverse transcription,polymerase chain reaction, accompanied by up-regulation of signal transducer and activator of transcription-1 (STAT1) phosphorylation in B cells in response to HCV core protein, with the opposite pattern observed in HCV core-treated T cells. This study demonstrates differential regulation of B and T lymphocytes by HCV core and supports a mechanism by which lymphocyte dysregulation occurs in the course of persistent HCV infection. [source] Differential regulation of platelet-derived growth factor stimulated migration and proliferation in osteoblastic cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2004Meenal Mehrotra Abstract Osteoblastic migration and proliferation in response to growth factors are essential for skeletal development, bone remodeling, and fracture repair, as well as pathologic processes, such as metastasis. We studied migration in response to platelet-derived growth factor (PDGF, 10 ng/ml) in a wounding model. PDGF stimulated a twofold increase in migration of osteoblastic MC3T3-E1 cells and murine calvarial osteoblasts over 24,48 h. PDGF also stimulated a tenfold increase in 3H-thymidine (3H-TdR) incorporation in MC3T3-E1 cells. Migration and DNA replication, as measured by BrdU incorporation, could be stimulated in the same cell. Blocking DNA replication with aphidicolin did not reduce the distance migrated. To examine the role of mitogen-activated protein (MAP) kinases in migration and proliferation, we used specific inhibitors of p38 MAP kinase, extracellular signal regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). For these signaling studies, proliferation was measured by carboxyfluorescein diacetate succinimidyl ester (CFSE) using flow cytometry. Inhibition of the p38 MAP kinase pathway by SB203580 and SB202190 blocked PDGF-stimulated migration but had no effect on proliferation. Inhibition of the ERK pathway by PD98059 and U0126 inhibited proliferation but did not inhibit migration. Inhibition of JNK activity by SP600125 inhibited both migration and proliferation. Hence, the stimulation of migration and proliferation by PDGF occurred by both overlapping and independent pathways. The JNK pathway was involved in both migration and proliferation, whereas the p38 pathway was predominantly involved in migration and the ERK pathway predominantly involved in proliferation. © 2004 Wiley-Liss, Inc. [source] Differential regulation of protein expression, growth and apoptosis by natural and synthetic retinoidsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2003M.A. Christine Pratt Abstract All- trans retinoic acid (ATRA) can down regulate the anti-apoptotic protein Bcl-2 and the cell cycle proteins cyclin D1 and cdk2 in estrogen receptor-positive breast cancer cells. We show here that retinoids can also reduce expression of the inhibitor of apoptosis protein, survivin. Here we have compared the regulation of these proteins in MCF-7 and ZR-75 breast cancer cells by natural and synthetic retinoids selective for the RA receptors (RARs) ,, ,, and , then correlated these with growth inhibition, induction of apoptosis and chemosensitization to Taxol. In both cell lines ATRA and 9- cis RA induced the most profound decreases in cyclin D1 and cdk2 expression and also mediated the largest growth inhibition. The RAR, agonist, Ro 40-6055 also strongly downregulated these proteins although did not produce an equivalent decrease in S-phase cells. Only ATRA induced RAR, expression. ATRA, 9- cis RA and 4-HPR initiated the highest level of apoptosis as determined by mitochondrial Bax translocation, while only ATRA and 9- cis RA strongly reduced Bcl-2 and survivin protein expression. Enumeration of dead cells over 96 h correlated well with downregulation of both survivin and Bcl-2. Simultaneous retinoid-mediated reduction of both these proteins also predicted optimal Taxol sensitization. 4-HPR was much weaker than the natural retinoids with respect to Taxol sensitization, consistent with the proposed requirement for reduced Bcl-2 in this synergy. Neither the extent of cell cycle protein regulation nor AP-1 inhibition fully predicted the antiproliferative effect of the synthetic retinoids suggesting that growth inhibition requires regulation of a spectrum of RAR-regulated gene products in addition even to pivotal cell cycle proteins. © 2003 Wiley-Liss, Inc. [source] Differential regulation of P-glycoprotein genes in primary rat hepatocytes by collagen sandwich and drugsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2002Chow H. Lee Abstract P-glycoprotein (Pgp) is a small family of plasma membrane proteins, which are capable of transporting substrates across cell membranes. Class I and II Pgp are able to transport drugs and have been shown to mediate multidrug resistance (MDR). Class III Pgp is a long chain phospholipid transporter and does not mediate MDR. The regulation of all three Pgp genes is still poorly understood. For instance, it is not clear if the three Pgp genes are co-regulated or differentially regulated by external stimuli. This study examined the effect of drugs and collagen sandwich system on expression and transcription of all the three Pgp genes in primary rat hepatocytes. Consistent with previous findings, dramatic overexpression (25-fold) of Class II Pgp mRNA was seen, upon culturing of hepatocytes onto a single layered collagen gel. Hepatocytes sandwiched between two layers of collagen gel exhibited decreased (4.5-fold) Class II Pgp mRNA expression as compared to the single layer system. Treatment of hepatocytes cultured on the single layer collagen system with cytoskeletal disrupting (cytochalasin D, colchicine) but not cytoskeletal stabilizing (phalloidin, taxol) drugs, suppressed Class II Pgp expression. In all cases, no change in Class II Pgp transcription was observed as demonstrated by nuclear run-on studies. This suggests that collagen configuration and drugs affect Class II Pgp mRNA expression predominantly through post-transcriptional mechanisms. In contrast, parallel increases in mRNA expression and transcription of Class I Pgp gene were observed upon culturing of hepatocytes, in the collagen sandwich system, and treatment with some drugs (cytochalasin D, colchicine, and phalloidin). This suggests that Class I Pgp gene is regulated primarily via transcriptional mechanisms by these stimuli. On the other hand, Class III Pgp gene appears to be post-transcriptionally co-regulated with Class II Pgp gene by treatment with the drugs, while collagen configuration affected both transcription and post-transcription of Class III Pgp gene. Finally, dose-dependent studies using cycloheximide provided further evidence that the two MDR-associated genes are not co-regulated. This study has implications for future studies on the molecular mechanisms of Pgp gene regulation. J. Cell. Biochem. 86: 12,20, 2002. © 2002 Wiley-Liss, Inc. [source] Differential regulation of NMDA receptor function by DJ-1 and PINK1AGING CELL, Issue 5 2010Ning Chang Summary Dysfunction of PTEN-induced kinase 1 (PINK1) or DJ-1 promotes neuronal death and is implicated in the pathogenesis of Parkinson's disease, but the underlying mechanisms remain unclear. Given the roles of N -methyl- d- aspartate receptor (NMDAr)-mediated neurotoxicity in various brain disorders including cerebral ischemia and neurodegenerative diseases, we investigated the effects of PINK1 and DJ-1 on NMDAr function. Using protein overexpression and knockdown approaches, we showed that PINK1 increased NMDAr-mediated whole-cell currents by enhancing the function of NR2A-containing NMDAr subtype (NR2ACNR). However, DJ-1 decreased NMDAr-mediated currents, which was mediated through the inhibition of both NR2ACNR and NR2B-containing NMDAr subtype (NR2BCNR). We revealed that the knockdown of DJ-1 enhanced PTEN expression, which not only potentiated NR2BCNR function but also increased PINK1 expression that led to NR2ACNR potentiation. These results indicate that NMDAr function is differentially regulated by DJ-1-dependent signal pathways DJ-1/PTEN/NR2BCNR and DJ-1/PTEN/PINK1/NR2ACNR. Our results further showed that the suppression of DJ-1, while promoted NMDA-induced neuronal death through the overactivation of PTEN/NR2BCNR-dependent cell death pathway, induced a neuroprotective effect to counteract DJ-1 dysfunction-mediated neuronal death signaling through activating PTEN/PINK1/NR2ACNR cell survival,promoting pathway. Thus, PINK1 acts with DJ-1 in a common pathway to regulate NMDAr-mediated neuronal death. This study suggests that the DJ-1/PTEN/NR2BCNR and DJ-1/PTEN/PINK1/NR2ACNR pathways may represent potential therapeutic targets for the development of neuroprotection strategy in the treatment of brain injuries and neurodegenerative diseases such as Parkinson's disease. [source] Altered gene expression in frontal cortex and midbrain of 3,4-methylenedioxymethamphetamine (MDMA) treated mice: Differential regulation of GABA transporter subtypesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2003Weiping Peng Abstract Changes in gene expression were examined in the brain of mice treated with a drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, also called Ecstasy). Frontal cortex and midbrain mRNA, analyzed by differential display polymerase chain reaction (DD-PCR) method, showed an altered expression of several cDNAs, 11 of which were isolated, cloned and sequenced. The sequence of one MDMA-induced mRNA corresponds (99.3%) to the mouse ,-amino butyric acid (GABA) transporter 1 (mGAT1). The established involvement of GABA neurotransmission in the activity of several abused drugs prompted us to focus herein on MDMA effect on the GABA transporter gene family. Semi-quantitative PCR analysis with primers selective to the reported mGAT1 sequence confirmed that MDMA treatment increased mGAT1 expression. Time-course study of the expression of the three GABA transporter subtypes showed that MDMA induced a differential temporal activation of mGAT1 and mGAT4, but had no effect on mGAT2. Quantitative real-time PCR further proved the increased expression of mGAT1 and mGAT4 upon MDMA treatment. Western immunoblotting with anti-GAT1 antibodies showed that MDMA also increased GAT1 protein levels, suggesting that neurotransmission of GABA was altered. MDMA effect was also verified in serotonin transporter knockout (,/,) mice that are insensitive behaviorally to MDMA; the drug did not increase GAT1 protein level in these mutants. In mice, tiagabine and NO-711, inhibitors of GABA transporters, restrained MDMA-induced acute toxicity and death. These results should facilitate novel approaches to prevent deleterious effects, including fatality, induced by MDMA and similar abused psychostimulants. © 2003 Wiley-Liss, Inc. [source] Differential regulation of blood vessel formation between standard and delayed bone healingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 9 2009Jasmin Lienau Abstract Blood vessel formation is a prerequisite for bone healing. In this study, we tested the hypothesis that a delay in bone healing is associated with an altered regulation of blood vessel formation. A tibial osteotomy was performed in two groups of sheep and stabilized with either a rigid external fixator leading to standard healing or with a highly rotationally unstable one leading to delayed healing. At days 4, 7, 9, 11, 14, 21, and 42 after surgery, total RNA was extracted from the callus. Gene expressions of vWF, an endothelial cell marker, and of several molecules related to blood vessel formation were studied by qPCR. Furthermore, histology was performed on fracture hematoma and callus sections. Histologically, the first blood vessels were detected at day 7 in both groups. mRNA expression levels of vWF, Ang1, Ang2, VEGF, CYR61, FGF2, MMP2, and TIMP1 were distinctly lower in the delayed compared to the standard healing group at several time points. Based on differential expression patterns, days 7 and 21 postoperatively were revealed to be essential time points for vascularization of the ovine fracture callus. This work demonstrates for the first time a differential regulation of blood vessel formation between standard and mechanically induced delayed healing in a sheep osteotomy model. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Differential regulation of immune responses by odontoblastsMOLECULAR ORAL MICROBIOLOGY, Issue 1 2007O. Veerayutthwilai Odontoblasts (OBs) are cells lining the inner surface of the tooth. Their potential role in host defenses within the tooth is suggested by their production of antimicrobial , -defensins, but their role needs confirmation. The present study sought to define the roles of human OBs in microbial recognition and innate host responses. Toll-like receptor 2 (TLR2) and TLR4, as well as CCR6, were immunolocalized in human OBs and their dentinal processes in situ. To examine OB function we used organotypic tooth crown cultures to maintain human OBs within their dentin scaffold. Cells in the OB layer of cultured and non-cultured crown preparations expressed mRNA for several markers of innate immunity including chemokine CCL20, chemokine receptor CCR6, TLR2, TLR4 and the OB marker dentin sialophosphoprotein (DSPP). Expression of human , -defensin 1 (hBD1), hBD2, hBD3, interleukin-8 (IL-8), and CCL20 increased with time in culture. Tooth crown odontoblast (TcOB) cultures were stimulated with agonist that was specific for TLR2 (Pam3CSK4) or TLR4 [Escherichia coli lipopolysaccharide (LPS)]. Nuclear factor- ,B assays confirmed the TLR2 activity of Pam3CSK4 and the TLR4 activity of LPS. LPS up-regulated IL-1,, tumor necrosis factor- , (TNF- ,), CCL20, hBD2, IL-8, TLR2 and TLR4; however, Pam3CSK4 down-regulated these mRNAs. IL-1,, TNF- ,, CCL20 were also up-regulated from six-fold to 30-fold in TcOB preparations from decayed teeth. Our results show for the first time that OBs express microbial pattern recognition receptors in situ, thus allowing differential responses to gram-positive and gram-negative bacteria, and suggest that pro-inflammatory cytokines and innate immune responses in decayed teeth may result from TLR4 signaling. [source] Differential regulation of the Oct-3/4 gene in cell culture model systems that parallel different stages of mammalian developmentMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2008Sunil Kumar Mallanna Abstract Oct-3/4 is an essential transcription factor that regulates stem cell fate during embryogenesis. Previous reports have shown that the Oct-3/4 gene utilizes different enhancers to regulate its expression as development proceeds. However, the cis -elements contributing to the differential activity of these enhancers require further study. Here, we investigated the function of the HMG/POU cassette and LRH-1 site present in the distal enhancer (DE) and the proximal enhancer, respectively. F9 and P19 EC cells were the focus of this study because their differential utilization of Oct-3/4 enhancers parallels the use of these enhancers during different stages of development. We determined that the LRH-1 site functions as a positive and a negative cis -regulatory element in P19 and F9 EC cells, respectively. Furthermore, we determined that the HMG/POU cassette in the DE strongly activates the Oct-3/4 promoter in F9 cells, but is a much weaker positive regulatory element in P19 cells. Given that HMG/POU cassettes play key roles in the regulation of at least seven essential genes, the Oct-3/4 HMG/POU cassette was examined more closely by focusing on Sox2, which can bind to HMG/POU cassettes. Although chromatin immunoprecipitation demonstrated that Sox2 binds to the Oct-3/4 gene equally well in both EC cell lines, tethering Sox2 to the region of the HMG/POU cassette only activated the Oct-3/4 promoter in F9 EC cells. These and other findings suggest that the differential activity of the HMG/POU cassette of the Oct-3/4 gene in EC cells is due to differential action of Sox2 and its associated co-factors. Mol. Reprod. Dev. 75: 1247,1257, 2008. © 2008 Wiley-Liss, Inc. [source] Differential regulation of ACC synthase genes in cold-dependent and -independent ripening in pear fruitPLANT CELL & ENVIRONMENT, Issue 10 2004I. EL-SHARKAWY ABSTRACT Late pear cultivars such as Passe-Crassane (PC) require a long chilling treatment before they are capable of ripening. Early cultivars such as Old-Home (OH) have no cold prerequisite. The regulation of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) genes was studied in OH, PC and in OH × PC hybrids in order to determine the role of this gene family in the cold requirement. Of the seven Pc-ACS cDNAs isolated, four (Pc-ACS1a/b and Pc-ACS2a/b) showed differential expression associated with the cold requirement. Pc-ACS1a transcripts accumulated throughout the cold treatment and, with Pc-ACS2a, during ripening of cold-dependent cultivars. Pc-ACS1b and Pc-ACS2b were detected only during ripening of cold-independent genotypes. Furthermore, Pc-ACS2a transcript accumulation was negatively regulated by ethylene, whereas Pc-ACS2b was positively regulated by the hormone. Pc-ACS3, 4 and 5 transcript accumulation was similar in all genotypes. Genetic analyses of OH, PC, and 22 OH × PC progenies demonstrated that late, cold-dependent cultivars were homozygous for Pc-ACS1a and 2a whereas early, cold-independent cultivars were heterozygous for Pc-ACS1(a/b) and homozygous for Pc-ACS2b. A model is presented in which differences in Pc-ACS alleles and gene expression between cold- and non-cold-requiring pears are critical in determining the ripening behaviour of the cultivars. [source] Differential regulation of closely related R2R3-MYB transcription factors controls flavonol accumulation in different parts of the Arabidopsis thaliana seedlingTHE PLANT JOURNAL, Issue 4 2007Ralf Stracke Summary The genes MYB11, MYB12 and MYB111 share significant structural similarity and form subgroup 7 of the Arabidopsis thaliana R2R3-MYB gene family. To determine the regulatory potential of these three transcription factors, we used a combination of genetic, functional genomics and metabolite analysis approaches. MYB11, MYB12 and MYB111 show a high degree of functional similarity and display very similar target gene specificity for several genes of flavonoid biosynthesis, including CHALCONE SYNTHASE, CHALCONE ISOMERASE, FLAVANONE 3-HYDROXYLASE and FLAVONOL SYNTHASE1. Seedlings of the triple mutant myb11 myb12 myb111, which genetically lack a complete subgroup of R2R3-MYB genes, do not form flavonols while the accumulation of anthocyanins is not affected. In developing seedlings, MYB11, MYB12 and MYB111 act in an additive manner due to their differential spatial activity; MYB12 controls flavonol biosynthesis mainly in the root, while MYB111 controls flavonol biosynthesis primarily in cotyledons. We identified and confirmed additional target genes of the R2R3-MYB subgroup 7 factors, including the UDP-glycosyltransferases UGT91A1 and UGT84A1, and we demonstrate that the accumulation of distinct and structurally identified flavonol glycosides in seedlings correlates with the expression domains of the different R2R3-MYB factors. Therefore, we refer to these genes as PFG1,3 for ,PRODUCTION OF FLAVONOL GLYCOSIDES'. [source] Differential regulation of TGA transcription factors by post-transcriptional controlTHE PLANT JOURNAL, Issue 5 2002Dominique Pontier Summary Transcription factors often belong to multigene families and their individual contribution in a particular regulatory network remains difficult to assess. We show here that specific members from a family of conserved Arabidopsis bZIP transcription factors, the TGA proteins, are regulated in their protein stability by developmental stage-specific proteolysis. Using GFP fusions of three different Arabidopsis TGA factors that represent members of distinct subclasses of the TGA factor family, we demonstrate that two of these TGA proteins are specifically targeted for proteolysis in mature leaf cells. Using a supershift gel mobility assay, we found evidence for similar regulation of the cognate proteins as compared to the GFP fusion proteins expressed under the cauliflower mosaic virus (CaMV) 35S promoter. Using various inhibitors, we showed that the expression of at least one of these three TGA factors could be stabilized by inhibition of proteasome-mediated proteolysis. This study indicates that TGA transcription factors may be regulated by distinct pathways of targeted proteolysis that can serve to modulate the contribution of specific members of a multigene family in complex regulatory pathways. [source] Trichloroethylene effects on gene expression during cardiac developmentBIRTH DEFECTS RESEARCH, Issue 7 2003J. Michael Collier Abstract BACKGROUND Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. Our study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague-Dawley rats exposed to trichloroethylene (TCE) or potential bio-transformation products dichloroethylene (DCE) and trichloroacetic acid (TCAA). METHODS cDNA subtractive hybridization was used to selectively amplify expressed mRNA obtained from control or halogenated hydrocarbon exposed rat embryos. The doses used were 1100 and 110 ppm (8300 and 830 ,M) TCE, 110 and 11 ppm (1100 and 110 ,M) DCE, and 27.3 and 2.75 mg/ml (100 and 10 mM) TCAA. Control animals were given distilled drinking water throughout the period of experiments. RESULTS Sequencing of over 100 clones derived from halogenated hydrocarbon exposed groups resulted in identification of numerous differentially regulated gene sequences. Up-regulated transcripts identified include genes associated with stress response (Hsp 70) and homeostasis (several ribosomal proteins). Down-regulated transcripts include extracellular matrix components (GPI-p137 and vimentin) and Ca2+ responsive proteins (Serca-2 Ca2+ -ATPase and ,-catenin). Two possible markers for fetal TCE exposure were identified: Serca-2 Ca2+ -ATPase and GPI-p137, a GPI-linked protein of unknown function. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi-quantitative RT-PCR with levels of TCE exposure between 100 and 250 ppb (0.76 and 1.9 ,M) sufficient to decrease expression. CONCLUSIONS Sequences down-regulated with TCE exposure appear to be those associated with cellular housekeeping, cell adhesion, and developmental processes, while TCE exposure up-regulates expression of numerous stress response and homeostatic genes. Birth Defects Research (Part A) 67488,495, 2003. © 2003 Wiley-Liss, Inc. [source] Differential regulation of nitric oxide synthase isoforms in experimental acute Chagasic cardiomyopathyCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2000B. Chandrasekar We have previously demonstrated induction and high level expression of IL-1,, IL-6 and tumour necrosis factor-alpha in the myocardium during the acute stage of experimental Trypanosoma cruzi infection (Chagas' disease). The myocardial depressive effects of these cytokines are mediated in part by the induction of nitric oxide synthase (NOS), production of nitric oxide (NO) and formation of peroxynitrite. In this study we investigated the expression, activity and localization of NOS isoforms, and the levels of NO, malondialdehyde (a measure of oxidative stress), and peroxynitrite in rats at 1·5, 5, 10 and 15 days after infection with T. cruzi trypomastigotes. The myocardial inflammatory infiltrate and number of amastigote nests increased over the course of infection. A significant increase in tissue nitrate + nitrite levels, NOS2 mRNA, and NOS2 enzyme activity was observed at all time points in the infected compared with uninfected animals. The enzyme activity of constitutive NOS, tissue malondialdehyde levels, and NOS3 mRNA levels was only transiently increased after infection. The protein levels of the NOS isoforms paralleled their mRNA expression. While no positive nitrotyrosine immunoreactivity was detected in control myocardium, its levels increased in infected animals over time. Thus, by 1·5 days post-infection, when no parasite or immune cell infiltration could be detected, the myocardium expressed high levels of NOS and NO metabolites. Nevertheless, the early production of NO in the myocardium was not sufficient to clear the parasites. [source] Individual differences in the effects of chronic prazosin hydrochloride treatment on hippocampal mineralocorticoid and glucocorticoid receptorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2007Mohamed Kabbaj Abstract The aim of this study was to investigate the noradrenergic regulation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) in high responder (HR) and low responder (LR) male rats, an animal model of individual differences in hypothalamo-pituitary-adrenal axis activity and vulnerability to drugs of abuse. The effects of a chronic treatment with the noradrenergic ,1 antagonist (1-[4-amino-6,7-dimethoxy-2-quinazolinyl]-4-[2-furanylcarbonyl] piperazine) hydrochloride (prazosin) (0.5 mg/kg, i.p., 35 days) were assessed on stress-induced corticosterone (CORT) secretion and on hippocampal MRs and GRs in adrenally intact rats. In order to ascertain whether the effects of chronic prazosin treatment on hippocampal MRs and GRs were direct or indirect, through prazosin-induced CORT secretion, we also assessed the effects of the same treatment on adrenalectomized rats with CORT substitutive therapy. When compared with LR rats, HR rats exhibited a delayed return to the basal level of CORT following acute restraint stress; this was associated with a lower binding of MRs and GRs in HR rats than in LR rats. Chronic prazosin treatment had no effect in HR animals but markedly reduced hippocampal MRs and GRs, and increased stress-induced CORT secretion in LR rats. In LR adrenalectomized rats, prazosin reduced hipppocampal MRs but did not change GRs. Our results provide evidence of a differential regulation by noradrenaline of hippocampal MRs and GRs in HR and LR rats. These data could have clinical implications in terms of individual differences in the resistance to antidepressant treatments and individual differences in drug abuse. [source] Transcriptional regulation of ASK/Dbf4 in cutaneous melanoma is dependent on E2F1EXPERIMENTAL DERMATOLOGY, Issue 12 2008Sandeep Nambiar Background:, Melanoma is a complex genetic disease, the management of which will require an in-depth understanding of the biology underlying its initiation and progression. Recently, we have reported the differential regulation of a novel gene, namely ASK/Dbf4, in melanoma and suggested upregulation of ASK/Dbf4 as a novel molecular determinant with prognostic relevance that confers a proliferative advantage in cutaneous melanoma. As trans -acting factor binding is fundamental to understand the regulation of gene expression, this study focuses on characterization of the specific transcriptional regulation of ASK/Dbf4 in melanoma. Objective:, We investigated whether ASK/Dbf4 is a transcriptional target of the important cell cycle regulator E2F1 in melanoma. Results:, As evidenced by gel supershift assays on nuclear extracts from various melanoma cell lines (SK-MEL-28, MV3, M13, A375 and BLM), E2F1 bound to the ASK/Dbf4 minimal promoter (MP). In addition, cisplatin-mediated abrogation of E2F1 binding to the ASK/Dbf4 MP resulted in a transcriptional decrease in ASK/Dbf4. Further, the current study also demonstrated that ASK/Dbf4 regulation was refractory to UVB, a well-known risk factor for melanoma. Conclusions:, In summary, our study not only elucidated that ASK/Dbf4, a novel cell survival gene in melanoma was transcriptionally regulated by E2F1, but also that the induction of ASK/Dbf4 was refractory to UVB exposure suggesting that its upregulation was not an early event in melanomagenesis. [source] Malonyl-CoA decarboxylase (MCD) is differentially regulated in subcellular compartments by 5,AMP-activated protein kinase (AMPK)FEBS JOURNAL, Issue 13 2004AMPK by adenoviral gene transfer technique, Studies using H9c2 cells overexpressing MCD Malonyl-CoA, a potent inhibitor of carnitine pamitoyl transferase-I (CPT-I), plays a pivotal role in fuel selection in cardiac muscle. Malonyl-CoA decarboxylase (MCD) catalyzes the degradation of malonyl-CoA, removes a potent allosteric inhibition on CPT-I and thereby increases fatty acid oxidation in the heart. Although MCD has several Ser/Thr phosphorylation sites, whether it is regulated by AMP-activated protein kinase (AMPK) has been controversial. We therefore overexpressed MCD (Ad.MCD) and constitutively active AMPK (Ad.CA-AMPK) in H9c2 cells, using an adenoviral gene delivery approach in order to examine if MCD is regulated by AMPK. Cells infected with Ad.CA-AMPK demonstrated a fourfold increase in AMPK activity as compared with control cells expressing green fluorescent protein (Ad.GFP). MCD activity increased 40- to 50-fold in Ad.MCD + Ad.GFP cells when compared with Ad.GFP control. Co-expressing AMPK with MCD further augmented MCD expression and activity in Ad.MCD + Ad.CA-AMPK cells compared with the Ad.MCD + Ad.GFP control. Subcellular fractionation further revealed that 54.7 kDa isoform of MCD expression was significantly higher in cytosolic fractions of Ad.MCD + Ad.CA-AMPK cells than of the Ad.MCD +Ad.GFP control. However, the MCD activities in cytosolic fractions were not different between the two groups. Interestingly, in the mitochondrial fractions, MCD activity significantly increased in Ad.MCD + Ad.CA-AMPK cells when compared with Ad.MCD + Ad.GFP cells. Using phosphoserine and phosphothreonine antibodies, no phosphorylation of MCD by AMPK was observed. The increase in MCD activity in mitochondria-rich fractions of Ad.MCD + Ad.CA-AMPK cells was accompanied by an increase in the level of the 50.7 kDa isoform of MCD protein in the mitochondria. This differential regulation of MCD expression and activity in the mitochondria by AMPK may potentially regulate malonyl-CoA levels at sites nearby CPT-I on the mitochondria. [source] Phosphorylation of NF-,B proteins by cyclic GMP-dependent kinaseFEBS JOURNAL, Issue 10 2003A noncanonical pathway to NF-, B activation The transcription factor NF-,B is activated in cellular stress responses. This requires rapid regulation of its function, which is accomplished, in part, by various modes of phosphorylation. Even though diverse DNA binding subunits of NF-,B proteins may transactivate from distinct recognition sequences, the differential regulation of transcription from the large number of NF-,B responsive sites in various gene promoters and enhancers has been incompletely understood. The cyclic GMP-dependent kinase (PKG) is an important mediator of signal transduction that may induce gene expression through cAMP response element binding protein (CREB) and through other, yet undefined, mechanisms. We have previously characterized a signal transduction pathway that leads to activation-induced cell death in T-lymphocytes and involves the activation of PKG. Here we demonstrate that the NF-,B proteins p65, p49 (also called p52), and p50 are specific substrates for this kinase. PKG dose-dependently increases the transactivating activity of p65 from the NF-,B consensus sequence. It also mediates dose-dependently an increase in transcriptional activity by p49 or p50 from a unique CCAAT/enhance binding protein (C/EBP)-associated NF-,B site, but not from the consensus site. Phosphorylation of p65, p50, or p49 does not alter their subcellular distribution. Because the release of cytosolic p65/p50 heterodimers into the nucleus is by itself insufficient to differentiate all the numerous NF-,B promoter sequences, phosphorylation of the DNA-binding subunits reveals a form of differential regulation of NF-,B activity and it implies a novel pathway for PKG-induced gene transcription. These observations may bear on mechanisms of programmed cell death in T-lymphocytes. They may also be relevant to ongoing efforts to induce cancer cell apoptosis through activation of PKG. [source] Interferon-, and lipopolysaccharide regulate the expression of Nramp2 and increase the uptake of iron from low relative molecular mass complexes by macrophagesFEBS JOURNAL, Issue 22 2000S. L. Wardrop The natural resistance associated macrophage protein 2 (Nramp2) is a transporter that is involved in iron (Fe) uptake from transferrin (Tf) and low molecular mass Fe complexes. Here we describe the effect of the inflammatory mediators interferon-, (IFN-,) and lipopolysaccharide (LPS) on the expression of Nramp2 mRNA and Fe uptake by cells of the macrophage lineage. After incubation of the RAW264.7 macrophage cell line with LPS there was a sevenfold increase in the expression of the 2.3 kb Nramp2 mRNA transcript when compared with the control, but little effect on the Nramp2 3.1 kb transcript. These results indicate differential regulation of the two transcripts. Treatment with LPS resulted in an increase in 59Fe uptake from 59Fe,nitrilotriacetic acid, while transferrin receptor (TfR) mRNA levels and 59Fe uptake from 59Fe,Tf were decreased. Paradoxically, at the same time, an increase in iron regulatory protein (IRP)1 RNA-binding activity was observed. Incubation with IFN-, (50 U·mL,1) resulted in a marked decrease in TfR mRNA levels but had no effect on Nramp2 mRNA expression. Exposure of RAW264.7 cells to both IFN-, and LPS resulted in a fourfold increase in the Nramp2 2.3-kb transcript and a four to fivefold decrease in the 3.1-kb transcript when compared with the control. Furthermore, there was a decrease in TfR mRNA levels despite an increase in IRP1 RNA-binding activity and a marked increase in inducible nitric oxide synthase mRNA expression. Hence, TfR and Nramp2 mRNA expression did not appear to be regulated in a concerted manner. Similar responses to those found above for RAW264.7 cells were also observed in the J774 macrophage cell line and also for primary cultures of mouse peritoneal macrophages. These results are of interest as the TfR and Nramp2 are thought to act together during Fe uptake from Tf. This is the first report to demonstrate regulation of the Nramp2 mRNA transcripts by inflammatory mediators. [source] Microbial interactions and differential protein expression in Staphylococcus aureus ,Candida albicans dual-species biofilmsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2010Brian M. Peters Abstract The fungal species Candida albicans and the bacterial species Staphylococcus aureus are responsible for a majority of hospital-acquired infections and often coinfect critically ill patients as complicating polymicrobial biofilms. To investigate biofilm structure during polymicrobial growth, dual-species biofilms were imaged with confocal scanning laser microscopy. Analyses revealed a unique biofilm architecture where S. aureus commonly associated with the hyphal elements of C. albicans. This physical interaction may provide staphylococci with an invasion strategy because candidal hyphae can penetrate through epithelial layers. To further understand the molecular mechanisms possibly responsible for previously demonstrated amplified virulence during coinfection, protein expression studies were undertaken. Differential in-gel electrophoresis identified a total of 27 proteins to be significantly differentially produced by these organisms during coculture biofilm growth. Among the upregulated staphylococcal proteins was l -lactate dehydrogenase 1, which confers resistance to host-derived oxidative stressors. Among the downregulated proteins was the global transcriptional repressor of virulence factors, CodY. These findings demonstrate that the hyphae-mediated enhanced pathogenesis of S. aureus may not only be due to physical interactions but can also be attributed to the differential regulation of specific virulence factors induced during polymicrobial growth. Further characterization of the intricate interaction between these pathogens at the molecular level is warranted, as it may aid in the design of novel therapeutic strategies aimed at combating fungal,bacterial polymicrobial infection. [source] Differential regulation of SOCS-1 signalling in B and T lymphocytes by hepatitis C virus core proteinIMMUNOLOGY, Issue 2 2008Zhi Qiang Yao Summary Hepatitis C virus (HCV) infection is characterized by a strong propensity toward chronicity, autoimmune phenomena and lymphomagenesis, supporting a role for lymphocyte dysregulation during persistent viral infection. We have shown that HCV core protein inhibits T-cell functions through interaction with a complement receptor, gC1qR. Here, we further report that B cells also express gC1qR that can be bound by HCV core protein. Importantly, using flow cytometry, we demonstrated differential regulation of B and T lymphocytes by the HCV core,gC1qR interaction, with down-regulation of CD69 activation in T cells but up-regulation of CD69 activation and cell proliferation in B cells. HCV core treatment led to decreased interferon-, production in CD8+ T cells but to increased immunoglobulin M and immunoglobulin G production as well as cell surface expression of costimulatory and chemokine receptors, including CD86 (B7-2), CD154 (CD40L) and CD195 (CCR5), in CD20+ B cells. Finally, we showed down-regulation of suppressor of cytokine signalling-1 (SOCS-1) using real-time reverse transcription,polymerase chain reaction, accompanied by up-regulation of signal transducer and activator of transcription-1 (STAT1) phosphorylation in B cells in response to HCV core protein, with the opposite pattern observed in HCV core-treated T cells. This study demonstrates differential regulation of B and T lymphocytes by HCV core and supports a mechanism by which lymphocyte dysregulation occurs in the course of persistent HCV infection. [source] | |||||||||||||||||||||||||||||||||||||