|
| ||
|
|
||
Cellular Responses (cellular + response)
Selected AbstractsMicropatterned Polymer Surfaces and Cellular Response of Dictyostelium,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Magdalena Eder Gecko inspired adhesives are surfaces with many microscale pillars that form Van der Waals forces with other surfaces. They differ from conventional tape in that adhesion is reversible and has the potential for switchability. These properties make gecko adhesives interesting for various biomedical applications. The two objectives of this project were to investigate the formation of biofilms on such surfaces and how the surfaces affect cell development. The developmental stages of the model organism Dictyostelium discoideum were observed by time lapse photography using light and environmental scanning electron microscopy. This study shows that micropatterned surfaces can be used as a biophysical tool to interfere with multicellular tissue formation in multiple ways. [source] Phase Reversion-Induced Nanograined/Ultrafine-Grained Structures in Austenitic Stainless Steel and their Significance in Modulating Cellular Response: Biochemical and Morphological Study with Fibroblasts,ADVANCED ENGINEERING MATERIALS, Issue 12 2009R. Devesh Kumar Misra Materials science, engineering, and biological sciences have been combined to improve the tissue compatibility of medical devices. In this regard, nano/ultrafine structuring of austenitic stainless steel obtained using an innovative approach of "phase-reversion" has been evaluated for modulation of cellular activity. The biochemical and morphology study with fibroblasts point toward the improvement of tissue compatibility on comparison with coarse-grained structures, strengthening the foundation of nanostructured materials for bio-medical applications. [source] Functional Mimicry of an Anti-idiotypic Antibody to Nominal Antigen on Cellular ResponseCANCER SCIENCE, Issue 1 2002Jie Ma One concept for immune therapy of cancer involves induction of antigen mimic antibodies to trigger the immune system into a response against the tumor cells. Anti-idiotypic antibodies (Ab2) directed against the antigen-combining site of other antibodies (Ab1) may functionally and even structurally mimic antigen and induce anti-anti-idiotypic immune response. We report here the generation of murine monoclonal antibody (mAb) WJ02 (Ab2) raised against the murine monoclonal immunoglobulin MJ01 (Ab1), which defines ovarian cancer antigen CA125. In enzyme immunoassays the binding of Ab2 to the variable region of Ab1 could be inhibited by CA125. In addition, the mimicry of mAb WJ02 to CA125 on cellular immune response was detected by human peripheral blood cells. The T cells primed by mAb WJ02 or CA125 proliferated in the presence of CA125 or mAb WJ02, respectively. Furthermore, T cells specific to mAb WJ02 could lyse ovarian cancer cells OVCAR-3 that express CA125. Finally, we proved that a patient immunized with mAb MJ01 could induce T cells that recognize mAb WJ02. In summary, we conclude that mAb WJ02 mimics CA125 on cellular response and such functional mimicry is one of the most important criteria to select Ab2 for cancer therapy. [source] Cellular response to oxidative stress: Signaling for suicide and survival,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2002Jennifer L. Martindale Reactive oxygen species (ROS), whether produced endogenously as a consequence of normal cell functions or derived from external sources, pose a constant threat to cells living in an aerobic environment as they can result in severe damage to DNA, protein, and lipids. The importance of oxidative damage to the pathogenesis of many diseases as well as to degenerative processes of aging has becoming increasingly apparent over the past few years. Cells contain a number of antioxidant defenses to minimize fluctuations in ROS, but ROS generation often exceeds the cell's antioxidant capacity, resulting in a condition termed oxidative stress. Host survival depends upon the ability of cells and tissues to adapt to or resist the stress, and repair or remove damaged molecules or cells. Numerous stress response mechanisms have evolved for these purposes, and they are rapidly activated in response to oxidative insults. Some of the pathways are preferentially linked to enhanced survival, while others are more frequently associated with cell death. Still others have been implicated in both extremes depending on the particular circumstances. In this review, we discuss the various signaling pathways known to be activated in response to oxidative stress in mammalian cells, the mechanisms leading to their activation, and their roles in influencing cell survival. These pathways constitute important avenues for therapeutic interventions aimed at limiting oxidative damage or attenuating its sequelae. Published 2002 Wiley-Liss, Inc. [source] Trafficking of neurokinin receptors: regulation, mechanism and functionEXPERIMENTAL DERMATOLOGY, Issue 9 2004N. Bunnett Cellular responses to agonists of G-protein-coupled receptors (GPCRs) depend in large part on the trafficking of receptors between the plasma membrane and intracellular locations. Receptor activation usually triggers rapid endocytosis of receptors, which either recycle to the cell surface or are targeted for degradation, depending on the receptor in question and the nature of the stimulation. Activation of neurokinin receptors (NKRs) induces membrane translocation of G-protein receptor kinases, which phosphorylate the receptors and ,-arrestins, which interact with phosphorylated receptors. ,-arrestins: 1) uncouple receptors from G-proteins to mediate desensitization; 2) are adaptors for clathrin and AP-2 and mediate clathrin and dynamin-dependent endocytosis of receptors; and 3) interact with components of the MAP kinase pathway such as src, and thereby determine the subcellular location and function of activated MAP kinases. The fate of endocytosed NKRs depends on the receptor and the nature of the stimulus. Transient stimulation with low concentrations of SP (1 nm, 10 min) induces rapid recycling of the NK1R from superficially located endosomes by a mechanism that is mediated by rab4a and rab11a. Higher concentrations of SP (10 nm) induce rab5a-dependent trafficking of the NK1R to perinuclear sorting endosomes and a gradual recycling to the plasma membrane. Continuous stimulation with high concentrations of SP (100 nm, 180 min) induces NK1R ubiquitination and trafficking for degradation. The fate of endocytosed receptors also depends on their interaction with ,-arrestins. The NK1R forms stable high-affinity interactions with both ,-arrestins 1 and 2 at the plasma membrane and in endosomes, whereas the NK3R interacts transiently only with ,-arrestin 2 at the cell surface. The nature of these interactions is specified by domains in the intracellular loop 3 and the carboxyl terminus and determine the rate of recycling and resensitization of these receptors. [source] Cellular responses in experimental liver injury: Possible cellular origins of regenerative stem-like progenitor cells,HEPATOLOGY, Issue 5 2005William B. Coleman Ph.D. Background/Aims Mature hepatocytes divide to restore liver mass after injury. However, when hepatocyte division is impaired by retrorsine poisoning, regeneration proceeds from another cell type: the small hepatocyte-like progenitor cells (SHPCs). Our aim was to test whether SHPCs could originate from mature hepatocytes. Methods Mature hepatocytes were genetically labeled using retroviral vectors harboring the ,-galactosidase gene. After labeling, retrorsine was administered to rats followed by partial hepatectomy to trigger regeneration. A liver biopsy was performed one month after surgery and rats were sacrificed one month later. Results We observed the proliferation of small hepatocytes arranged in clusters in liver biopsies. These cells expressed Ki67 antigen and displayed high mitotic index. At sacrifice, regeneration was completed and clusters had merged. A significant proportion of clusters also expressed ,-galactosidase demonstrating their origin from labeled mature hepatocytes. Finally, the overall proportion of ,-galactosidase positive cells was identical at the time of hepatectomy as well as in liver biopsy and at sacrifice. Conclusions The constant proportion of ,-galactosidase positive cells during the regeneration process demonstrates that mature hepatocytes are randomly recruited to proliferate and compensate parenchyma loss in this model. Furthermore, mature hepatocytes are the source of SHPC after retrorsine injury. [source] Cellular responses and cytokine profiles in Ascaris lumbricoides and Trichuris trichiura infected patientsPARASITE IMMUNOLOGY, Issue 11-12 2002Stefan M. Geiger SUMMARY The impact of intestinal helminth infection, i.e. Ascaris lumbricoides and Trichuris trichiura, on cellular responsiveness and cytokine production was investigated in young adults. Ascaris -specific cellular responsiveness was higher in parasite-free endemic controls than in patients infected with T. trichiura, or A. lumbricoides, or patients co-infected with both parasites. Also, mitogen-induced tumour necrosis factor (TNF)-,, interleukin (IL)-12 and interferon (IFN)-, secretion by peripheral blood mononuclear cells (PBMC) was higher in negative endemic controls than in infected individuals. Ascaris antigen-specific production of TNF-,, IL-12 and IFN-, was low in singly Ascaris as well as in co-infected patients, whereas secretion of IL-10 and IL-13 was elevated and similarly high in all patient groups. The detection of Trichuris -specific and Ascaris -specific IgG4 revealed significantly higher serum antibody levels in Trichuris or Ascaris patients when compared to endemic controls (P < 0·05), whereas parasite-specific IgE antibody levels were similarly high in infected individuals and in endemic controls. In summary, chronically infected Ascaris and Trichuris patients with a high parasite load presented reduced cellular reactivity and lower type 1 TNF-,, IFN-, and IL-12 responses when compared with endemic controls, whereas type 2 IL-10 and IL-13 productions were similar in all groups from the endemic area. The former may support parasite persistence, whereas substantial type 2 cytokine release may promote protective immunity, suggesting an adaptation of the host to control the parasite burden while minimizing immune-mediated host self-damage. [source] Cellular responses to Loa loa experimental infection in mandrills (Mandrillus sphinx) vaccinated with irradiated infective larvaePARASITE IMMUNOLOGY, Issue 4 2000Ungeheuer In order to shed light on the mechanisms of antifilarial protective immunity, we investigated the course of experimental loaiosis after vaccination in a nonhuman primate host, Mandrillus sphinx. Six vaccinated (V) mandrills received 50 irradiated L3 while six nonvaccinated (NV) received saline solution on days ,60, ,30 and ,15. All animals were challenged with 100 intact L3 (day 0). Parasitological and immunological status were followed for 9 months. Vaccination delayed the appearance and mean peak of microfilaraemia. Five mandrills (Mf,) were never microfilaraemic (one V mandrill) or microfilaraemic on only one occasion (2 V and 2 NV), the other seven having stable microfilaraemia (Mf+). The cytokine response of peripheral blood mononuclear cells to L3 (L3 Ag) was Th2 dominated, while microfilariae (Mf Ag) elicited a Th0-like response. During vaccination, Th2 cytokine production significantly increased in V mandrills against L3 Ag, as well as Mf Ag, whereas Th1 cytokines decreased. On day 60 postinoculation, cellular proliferation was higher in V mandrills in response to L3 and Mf Ags and PHA-L mitogen. At the end of prepatency (on day 130), mandrills with delayed appearance of microfilaraemia exhibited a high, transient IL-2 and IL-4 secretion in response to L3 Ag. Finally, high anti-Mf Th2 cytokine levels characterized Mf,mandrills not only during prepatency, but also (for IL-5) before immunization. However, the presence of a balanced Th1 anti-L3 response during prepatency in the amicrofilaraemic mandrill suggests its importance in protective immunity. Taken together, our data suggest that Th2 cells and also Th1 components of the antifilarial response, especially to larval antigen, may contribute to parasite elimination. [source] Signal transduction responses to lysophosphatidic acid and sphingosine 1-phosphate in human prostate cancer cellsTHE PROSTATE, Issue 14 2009Terra C. Gibbs Abstract BACKGROUND Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are lipid mediators that bind to G-protein-coupled receptors. In this study, signaling responses to 18:1 LPA and S1P were examined in parallel in three human prostate cancer cell lines: PC-3, Du145, and LNCaP. METHODS Receptor expression was assessed by RT-PCR, Northern blotting, and immunoblotting. Cellular responses to mediators were studied by proliferation assays, phosphoprotein immunoblotting, and phospholipid metabolism assays. RESULTS All cell lines express mRNA for both LPA and S1P receptors. PC-3 and Du145, but not LNCaP, proliferate in response to LPA and S1P. Epidermal growth factor (EGF), phorbol 12-myristate 13-acetate (PMA), LPA, and S1P induce activation of Erks in PC-3 and Du145; only EGF and PMA activate Erks in LNCaP. In Du145 and PC-3, Akt is activated by EGF, LPA, and S1P. Akt is constitutively active in LNCaP; EGF but not LPA or S1P stimulates further phosphorylation. FAK is phosphorylated in response to both LPA and S1P in PC-3 and Du145, but not in LNCaP. LPA and S1P stimulate phospholipase D (PLD) activity to varying extents in the different cell lines. Notably, both lipid mediators activate PLD in LNCaP. In Du145, LPA, but not S1P, activates PLD and enhances cellular production of LPA. CONCLUSIONS Although both LPA and S1P induce signal transduction in all prostate cancer cell lines studied, a proliferation response is observed only when the Erk, Akt, and FAK pathways are activated. Other responses to the lipid mediators, such as PLD activation, likely contribute to other cellular outcomes. Prostate 69: 1493,1506, 2009. © 2009 Wiley-Liss, Inc. [source] Autophagic pathways and metabolic stressDIABETES OBESITY & METABOLISM, Issue 2010S. Kaushik Autophagy is an essential intracellular process that mediates degradation of intracellular proteins and organelles in lysosomes. Autophagy was initially identified for its role as alternative source of energy when nutrients are scarce but, in recent years, a previously unknown role for this degradative pathway in the cellular response to stress has gained considerable attention. In this review, we focus on the novel findings linking autophagic function with metabolic stress resulting either from proteins or lipids. Proper autophagic activity is required in the cellular defense against proteotoxicity arising in the cytosol and also in the endoplasmic reticulum, where a vast amount of proteins are synthesized and folded. In addition, autophagy contributes to mobilization of intracellular lipid stores and may be central to lipid metabolism in certain cellular conditions. In this review, we focus on the interrelation between autophagy and different types of metabolic stress, specifically the stress resulting from the presence of misbehaving proteins within the cytosol or in the endoplasmic reticulum and the stress following a lipogenic challenge. We also comment on the consequences that chronic exposure to these metabolic stressors could have on autophagic function and on how this effect may underlie the basis of some common metabolic disorders. [source] Real-time monitoring of intracellular calcium dynamic mobilization of a single cardiomyocyte in a microfluidic chip pertaining to drug discoveryELECTROPHORESIS, Issue 24 2007Xiujun Li Abstract A microfluidic method for real-time quantitative measurement of cellular response pertaining to drug discovery is reported. This method is capable of multiple-step liquid delivery for measuring the drug response of a single cardiomyocyte, due to the improved cell retention by a newly designed chip. The chip, which consists of a cell-retention chamber with a weir structure, was fabricated just by a one-photomask microfabrication procedure followed by on-chip etching. This method differs from the conventional method, which uses two-mask photolithography to fabricate the microchannel (deep etch) and the weir structure (shallow etch). The dimensions of the weir structure have been predicted by a mathematical model, and confirmed by confocal microscopy. Using this microfluidic method, the dynamic [Ca2+]i mobilization in a single cardiomyocyte during its spontaneous contraction was quantified. Furthermore, we measured the cellular response of a cardiomyocyte on (i) a known cardiotonic agent (caffeine), (ii) a cardiotoxic chemotherapeutic drug (daunorubicin), and (iii) an herbal anticancer drug candidate , isoliquiritigenin (IQ) based on the fluorescent calcium measurement. It was found that IQ had produced a less pronounced effect on calcium mobilization of the cardiomyocytes whereas caffeine and daunorubicin had much stronger effects on the cells. These three experiments on cardiomyocytes pertaining to drug discovery were only possible after the improved cell retention provided by the new chip design (MV2) required for multiple-step real-time cellular analysis on a microchip, as compared with our old chip design (MV1). [source] Induction of V(D)J-mediated recombination of an extrachromosomal substrate following exposure to DNA-damaging agentsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2007Robert L. Pinsonneault Abstract V(D)J recombinase normally mediates recombination signal sequence (RSS) directed rearrangements of variable (V), diversity (D), and joining (J) germline gene segments that lead to the generation of diversified T cell receptor or immunoglobulin proteins in lymphoid cells. Of significant clinical importance is that V(D)J-recombinase-mediated rearrangements at immune RSS and nonimmune cryptic RSS (cRSS) have been implicated in the genomic alterations observed in lymphoid malignancies. There is growing evidence that exposure to DNA-damaging agents can increase the frequency of V(D)J-recombinase-mediated rearrangements in vivo in humans. In this study, we investigated the frequency of V(D)J-recombinase-mediated rearrangements of an extrachromosomal V(D)J plasmid substrate following exposure to alkylating agents and ionizing radiation. We observed significant dose- and time-dependent increases in V(D)J recombination frequency (V(D)J RF) following exposure to ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS) but not a nonreactive analogue, methylsulfone (MeSulf). We also observed a dose-dependent increase in V(D)J RF when cells were exposed to gamma radiation. The induction of V(D)J rearrangements following exposure to DNA-damaging agents was not associated with an increase in the expression of RAG 1/2 mRNA compared to unexposed controls or an increase in expression of the DNA repair Ku70, Ku80 or Artemis proteins of the nonhomologous end joining pathway. These studies demonstrate that genotoxic alkylating agents and ionizing radiation can induce V(D)J rearrangements through a cellular response that appears to be independent of differential expression of proteins involved with V(D)J recombination. Environ. Mol. Mutagen., 2007. © 2007 Wiley-Liss, Inc. [source] DNA damage and repair measurements from cryopreserved lymphocytes without cell culture,A reproducible assay for intervention studiesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 7 2006Jyh-Lurn Chang Abstract Single-cell gel electrophoresis (the Comet assay) can be used to measure DNA damage and DNA repair capacity (DRC). However, to test DRC of cryopreserved lymphocytes, published methods include steps for cell culturing and phytohemagglutinin stimulation, which may limit use of this assay in intervention studies. We developed a modified Comet assay protocol that allows us to measure DRC from cryopreserved lymphocytes without these in vitro manipulations. Assay reproducibility was evaluated by performing the assay six times on different dates using six aliquots from one blood draw of one individual. The interindividual variation was assessed by performing the assay using one aliquot from six individuals. When ,-irradiation was used as the mutagen, intra-assay coefficients of variation (CVs.) for baseline DNA damage, damage after ,-irradiation exposure, and DRC,measured as tail moment,were 8, 31, and 10%, respectively. Interindividual CVs. were higher. When H2O2 was used as the mutagen, intra-assay CVs. for damage measurements were lower for a protocol modification that included damage and repair at 37°C (CVs. ranging from 8 to 35%) than for the more standard 4°C protocol. Analyzing moment arm,the average distance of DNA migration within the tail,yielded similar results. DNA repair was successfully detected in each experiment. Comparing freshly isolated lymphocytes to cryopreserved lymphocytes from the same individuals' blood draw indicated that DRC was highly correlated when determined using moment arm values. This modified protocol extends the use of the Comet assay to measuring DRC in intervention studies (e.g., dietary interventions) in that it assesses cellular response after cryopreservation without cell culture or other extensive manipulation. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source] Alteration of normal cellular profiles in the scleractinian coral (Pocillopora damicornis) following laboratory exposure to fuel oilENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2006Luc Rougée Abstract Petroleum contamination from oil spills is a continuing threat to our ocean's fragile ecosystems. Herein, we explored the effects of the water-soluble fraction of crude oil on a stony coral, Pocillopora damicornis (Linneaeus 1758). We developed methods for exposing corals to various concentrations of crude oil and for assessing the potential molecular responses of the corals. Corals were exposed to water-accommodated fraction solutions, and appropriate cellular biomarkers were quantified. When compared to the "healthy" control specimens, exposed corals exhibited shifts in biomarker concentrations that were indicative of a shift from homeostasis. Significant changes were seen in cytochrome P450 1-class, cytochrome P450 2-class, glutathione- S -transferase-pi, and cnidarian multixenobiotic resistance protein-1 biomarkers, which are involved the cellular response to, and manipulation and excretion of, toxic compounds, including polycyclic aromatic hydrocarbons. A shift in biomarkers necessary for porphyrin production (e.g., protoporphyrinogen oxidase IX and ferrochelatase) and porphyrin destruction (e.g., heme oxygenase-1 and invertebrate neuroglobin homologue) illustrates only one of the cellular protective mechanisms. The response to oxidative stress was evaluated through measurements of copper/zinc superoxide dismutase-1 and DNA glycosylase MutY homologue-1 concentrations. Likewise, changes in heat shock protein 70 and small heat shock proteins indicated an adjustment in the cellular production of proteins. Finally, the results of this laboratory study were nearly identical to what we observed previously among corals of a different species, Porites lobata, exposed to an oil spill in the field after the grounding of the Merchant Vessel Kyowa Violet. [source] Signaling events leading to the curative effect of cystatin on experimental visceral leishmaniasis: Involvement of ERK1/2, NF-,B and JAK/STAT pathwaysEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2009Susanta Kar Abstract Curative effect of cystatin, a natural cystein protease inhibitor, on experimental visceral leishmaniasis was associated with strong upregulation of iNOS. The transductional mechanisms underlying this cellular response was investigated in the murine macrophage cell line RAW 264.7 and in the BALB/c mouse model of visceral leishmaniasis. Cystatin synergizes with IFN-, in inducing ERK1/2 phosphorylation and NF-,B DNA-binding activity. Pretreatment of cells with specific inhibitors of NF-,B or ERK1/2 pathway blocked the cystatin plus IFN-,-inducible NF-,B activity and markedly reduced the expression of iNOS at both mRNA and protein levels. Silencing of mitogen- and stress-activated protein kinase 1 significantly reduced cystatin-mediated NF-,B-dependent iNOS gene transcription suggesting the involvement of mitogen- and stress-activated protein kinase 1 activation in ERK1/2 signaling. DNA binding as well as silencing experiments revealed the requirement of IFN-,-mediated JAK-STAT activation even though cystatin did not modulate this signaling cascade by itself. In the in vivo situation, key steps in the activation cascade of NF-,B, including nuclear translocation of NF-,B subunits, I,B phosphorylation and I,B kinase, are all remarkably enhanced in Leishmania -infected mice by cystatin. Understanding the molecular mechanisms through which cystatin modulates macrophage effector responses will contribute to better define its potential for macrophage-associated diseases, in general. [source] Endoplasmic reticulum stress and the unfolded protein response are linked to synergistic IFN-, induction via X-box binding protein 1EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2008Judith A. Smith Dr. Abstract Type,I IFN are strongly induced upon engagement of certain pattern recognition receptors by microbial products, and play key roles in regulating innate and adaptive immunity. It has become apparent that the endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR), in addition to restoring ER homeostasis, also influences the expression of certain inflammatory cytokines. However, the extent to which UPR signaling regulates type,I IFN remains unclear. Here we show that cells undergoing a UPR respond to TLR4 and TLR3 ligands, and intracellular dsRNA, with log-fold greater IFN-, induction. This synergy is not dependent on autocrine type,I IFN signaling, but unexpectedly requires the UPR transcription factor X-box binding protein,1 (XBP-1). Synergistic IFN-, induction also occurs in HLA-B27/human ,2m-transgenic rat macrophages exhibiting a UPR as a consequence of HLA-B27 up-regulation, where it correlates with activation of XBP-1 splicing. Together these findings indicate that the cellular response to endogenous ,danger' that disrupts ER homeostasis is coupled to IFN-, induction by XBP-1, which has implications for the immune response and the pathogenesis of diseases involving the UPR. [source] Neutropenia alters lung cytokine production in mice and reduces their susceptibility to pulmonary cryptococcosisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2003Abstract Neutrophils are generally considered to contribute to host defense through their potent microbicidal activity. However, there is accumulating evidence that neutrophils also have an important regulatory role in establishing the balance of Th1 and Th2 responses. This study investigated the role of neutrophils in defense against pulmonary Cryptococcus neoformans infection using neutrophil-depleted BALB/c mice generated by administering mAb RB6,8C5. Neutropenic mice with pulmonary infection survived significantly longer than control mice, but there was no difference between groups infected intravenously. On day,1 of infection, neutropenic mice had significantly smaller fungal burdens than control mice. On day,7, neutropenic mice had significantly higher lung concentrations of IL-10, TNF-,, IL-4, and IL-12 than control mice, but there was no difference in IFN-, and MCP-1 levels. Neutrophils influenced the outcome of cryptococcal infection in mice through mechanisms that did not involve a reduction in early fungal burden. The absence of neutrophils in lung tissue during the initial stages of infection appeared to alter the inflammatory response in a manner thatwas subsequently beneficial to the host. Higher levels of Th1- and Th2-associated cytokines in neutropenic mice could have simultaneously promoted a strong cellular response while reducing inflammatory damage to the lung. Our results support the emerging concept that neutrophils play an important function in modulating the development of the immune response. [source] MAP-kinase-activated protein kinase 2 expression and activity is induced after neuronal depolarizationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2008Tobias Thomas Abstract Mitogen-activated protein kinase-activated protein kinase (MK)2 is one of several downstream targets of p38 mitogen-activated protein kinase and has a well documented role in inflammation. Here, we describe a possible new function of MK2. We show that triggering depolarization by potassium chloride or increasing the cellular cAMP by forskolin treatment led to elevated levels of expression and activity of mouse MK2. In both treatments, the kinase inhibitor H89 completely prevented the up-regulation of MK2 at the transcript level. By the use of different cell lines we demonstrated that the induction of MK2 expression is characteristic of neuronal cells and is absent in fibroblasts, macrophages and kidney cells. In vivo, induction of a status epilepticus by systemic administration of the chemoconvulsant kainic acid resulted in markedly reduced neurodegeneration in the pyramidal layer of the hippocampus, dentate gyrus and hilus of MK2-deficient mice compared with wild-type mice. Together, our data suggest a possible role of MK2 in the cellular response after neuronal depolarization, in particular in excitotoxicity. [source] Glial cell loss, proliferation and replacement in the contused murine spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2007Judith M. Lytle Abstract Studies in the rat have shown that contusive spinal cord injury (SCI) results in devastating pathology, including significant loss of mature oligodendrocytes and astrocytes even in spared white matter. Subsequently, there is increased proliferation of endogenous NG2+ cells, postulated to contribute to replacement of mature glia chronically, which is important for functional recovery. Studies of mechanisms that stimulate endogenous progenitor cells would be facilitated by using mouse models with naturally occurring and genetically engineered mutations. To determine whether the murine response is similar to that in the rat, we performed contusive SCI on adult female C57Bl/6 mice at the T8,9 level. Animals received bromodeoxyuridine injections in the first week following injury and were killed at 1, 3, 4, 7 or 28 days postinjury (DPI). The overall loss of macroglia and the temporal,spatial response of NG2+ cells after SCI in the (C57Bl/6) mouse was very similar to that in the (Sprague,Dawley) rat. By 24 h after SCI nearly half of the macroglia in spared ventral white matter had been lost. Cell proliferation was increased at 1,7 DPI, peaking at 3,4 DPI. Dividing cells included NG2+ cells and Cd11b+ macrophages and microglia. Furthermore, cells dividing in the first week expressed markers of mature glia at 28 DPI. The similarities in endogenous progenitor cell response to SCI in the mouse and rat suggest that this is a fundamental injury response, and that transgenic mouse models may be used to further probe how this cellular response to SCI might be enhanced to improve recovery after SCI. [source] Injury induced c-Jun expression and phosphorylation in the dopaminergic nigral neurons of the rat: correlation with neuronal death and modulation by glial-cell-line-derived neurotrophic factorEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2001Elisabetta Vaudano Abstract This study was designed to determine whether induction and phosphorylation of the transcription factor c-Jun is associated with lesion-induced death of dopaminergic neurons of the substantia nigra pars compacta, and if this cellular response is modulated by glial-cell-line-derived neurotrophic factor. In adult rats, delayed dopaminergic neuron cell death induced by intrastriatal 6-hydroxydopamine injection led to a marked increase in the number of both c-Jun- and phosphorylated c-Jun-immunoreactive nuclei in the substantia nigra pars compacta. The response was maximal before any significant loss of nigral neurons could be detected (on day 7 post lesion) and was confined to the dopaminergic neurons. Similarly, 6-hydroxydopamine lesion of the striatal dopaminergic terminals or excitotoxic lesion of the striatal target neurons in neonatal rats resulted in an increased number of c-Jun- and phosphorylated c-Jun-immunoreactive nigral nuclei that preceded the loss of nigral dopaminergic neurons. By contrast, after an excitotoxic lesion of the striatal target neurons in the adult rat, resulting in atrophy but not cell death of the nigral dopaminergic neurons, no upregulation of either c-Jun or phosphorylated c-Jun was found. A single injection of 10 µg of glial-cell-line-derived-neurotrophic factor given at day 3 after the intrastriatal 6-hydroxydopamine lesion reduced the number of c-Jun- and phosphorylated c-Jun-immunoreactive nuclei in the substantia nigra and protected the dopaminergic neurons from the ensuing cell death. We conclude that c-Jun induction and phosphorylation may be involved in the cellular events leading to death of nigral dopaminergic neurons in vivo and that this response can be modulated by glial-cell-line-derived-neurotrophic factor. [source] Intramembrane-sensing histidine kinases: a new family of cell envelope stress sensors in Firmicutes bacteriaFEMS MICROBIOLOGY LETTERS, Issue 2 2006Thorsten Mascher Abstract Two-component signal-transducing systems (TCS) consist of a histidine kinase (HK) that senses a specific environmental stimulus, and a cognate response regulator (RR) that mediates the cellular response. Most HK are membrane-anchored proteins harboring two domains: An extracytoplasmic input and a cytoplasmic transmitter (or kinase) domain, separated by transmembrane helices that are crucial for the intramolecular information flow. In contrast to the cytoplasmic domain, the input domain is highly variable, reflecting the plethora of different signals sensed. Intramembrane-sensing HK (IM-HK) are characterized by their short input domain, consisting solely of two putative transmembane helices. They lack an extracytoplasmic domain, indicative for a sensing process at or from within the membrane interface. Most proteins sharing this domain architecture are found in Firmicutes bacteria. Two major groups can be differentiated based on sequence similarity and genomic context: (1) BceS-like IM-HK that are functionally and genetically linked to ABC transporters, and (2) LiaS-like IM-HK, as part of three-component systems. Most IM-HK sense cell envelope stress, and identified target genes are often involved in maintaining cell envelope integrity, mediating antibiotic resistance, or detoxification processes. Therefore, IM-HK seem to constitute an important mechanism of cell envelope stress response in low G+C Gram-positive bacteria. [source] Novel insights into the osmotic stress response of yeastFEMS YEAST RESEARCH, Issue 3 2002Willem H Mager Abstract Response to hyperosmolarity in the baker's yeast Saccharomyces cerevisiae has attracted a great deal of attention of molecular and cellular biologists in recent years, from both the fundamental scientific and applied viewpoint. Indeed the underlying molecular mechanisms form a clear demonstration of the intricate interplay of (environmental) signalling events, regulation of gene expression and control of metabolism that is pivotal to any living cell. In this article we briefly review the cellular response to conditions of hyperosmolarity, with focus on the high-osmolarity glycerol mitogen-activated protein kinase pathway as the major signalling route governing cellular adaptations. Special attention will be paid to the recent finding that in the yeast cell also major structural changes occur in order to ensure maintenance of cell integrity. The intriguing role of glycerol in growth of yeast under (osmotic) stress conditions is highlighted. [source] Phosphatidylinositol 3-phosphate 5-kinase is required for the cellular response to nutritional starvation and mating pheromone signals in Schizosaccharomyces pombeGENES TO CELLS, Issue 2 2002Masayo Morishita Background: Phosphatidylinositol (3,5) bisphosphate, which is converted from phosphatidylinositol 3-phosphate by phosphatidylinositol 3-phosphate 5-kinase, is implicated in vacuolar functions and the sorting of cell surface proteins within endosomes in the endocytic pathway of budding yeast. A homologous protein, SpFab1p, has been found in the fission yeast Schizosaccharomyces pombe, but its role is not known. Results: Here we report that SpFab1p is encoded by ste12+ known as a fertility gene in S. pombe. The ste12 mutant grew normally under stress-free conditions, but was highly vacuolated and swelled at high temperatures and under starvation conditions. In nitrogen-free medium, ste12 cells were arrested in G1 phase, but partially defective in the expression of genes responsible for mating and meiosis. The ste12 mutant was defective both in the production of, and in the response to, mating pheromones. The amount of the pheromone receptor protein Map3p, was substantially decreased in ste12 cells. Map3p was transported to the cell surface, then internalized and eventually transported to the vacuolar lumen, even in the ste12 mutant. Conclusion: The results indicate that phosphatidylinositol(3,5)bisphosphate is essential for cellular responses to various stresses and for the mating pheromone signalling under starvation conditions. [source] Proteasome inhibition suppresses Schwann cell dedifferentiation in vitro and in vivoGLIA, Issue 16 2009Hyun Kyoung Lee Abstract The ubiquitin-proteasome system (UPS), lysosomes, and autophagy are essential protein degradation systems for the regulation of a variety of cellular physiological events including the cellular response to injury. It has recently been reported that the UPS and autophagy mediate the axonal degeneration caused by traumatic insults and the retrieval of nerve growth factors. In the peripheral nerves, axonal degeneration after injury is accompanied by myelin degradation, which is tightly related to the reactive changes of Schwann cells called dedifferentiation. In this study, we examined the role of the UPS, lysosomal proteases, and autophagy in the early phase of Wallerian degeneration of injured peripheral nerves. We found that nerve injury induced an increase in the ubiquitin conjugation and lysosomal-associated membrane protein-1 expression within 1 day without any biochemical evidence for autophagy activation. Using an ex vivo explant culture of the sciatic nerve, we observed that inhibiting proteasomes or lysosomal serine proteases prevented myelin degradation, whereas this was not observed when inhibiting autophagy. Interestingly, proteasome inhibition, but not leupeptin, prevented Schwann cells from inducing dedifferentiation markers such as p75 nerve growth factor receptor and glial fibrillary acidic protein in vitro and in vivo. In addition, proteasome inhibitors induced cell cycle arrest and cellular process formation in cultured Schwann cells. Taken together, these findings indicate that the UPS plays a role in the phenotype changes of Schwann cells in response to nerve injury. © 2009 Wiley-Liss, Inc. [source] HuR regulates gap junctional intercellular communication by controlling ,-catenin levels and adherens junction integrity,HEPATOLOGY, Issue 5 2009Niloofar Ale-Agha Gap junctional intercellular communication (GJIC) plays a critical role in the regulation of tissue homeostasis and carcinogenesis and is modulated by the levels, subcellular localization, and posttranslational modification of gap junction proteins, the connexins (Cx). Here, using oval cell-like rat liver epithelial cells, we demonstrate that the RNA-binding protein HuR promotes GJIC through two mechanisms. First, HuR silencing lowered the levels of Cx43 protein and Cx43 messenger RNA (mRNA), and decreased Cx43 mRNA half-life. This regulation was likely due to the direct stabilization of Cx43 mRNA by HuR, because HuR associated directly with Cx43 mRNA, a transcript that bears signature adenylate-uridylate-rich (AU-rich) and uridylate-rich (U-rich) sequences in its 3,-untranslated region. Second, HuR silencing reduced both half-life and the levels of ,-catenin mRNA, also a target of HuR; accordingly, HuR silencing lowered the levels of whole-cell and membrane-associated ,-catenin. Coimmunoprecipitation experiments showed a direct interaction between ,-catenin and Cx43. Small interfering RNA (siRNA)-mediated depletion of ,-catenin recapitulated the effects of decreasing HuR levels: it attenuated GJIC, decreased Cx43 levels, and redistributed Cx43 to the cytoplasm, suggesting that depletion of ,-catenin in HuR-silenced cells contributed to lowering Cx43 levels at the membrane. Finally, HuR was demonstrated to support GJIC after exposure to a genotoxic agent, doxorubicin, or an inducer of differentiation processes, retinoic acid, thus pointing to a crucial role of HuR in the cellular response to stress and in physiological processes modulated by GJIC. Conclusion: HuR promotes gap junctional intercellular communication in rat liver epithelial cells through two related regulatory processes, by enhancing the expression of Cx43 and by increasing the expression of ,-catenin, which, in turn, interacts with Cx43 and is required for proper positioning of Cx43 at the plasma membrane. (HEPATOLOGY 2009.) [source] Strength of signal: a fundamental mechanism for cell fate specificationIMMUNOLOGICAL REVIEWS, Issue 1 2006Sandra M. Hayes Summary:, How equipotent cells develop into complex tissues containing many diverse cell types is still a mystery. However, evidence is accumulating from different tissue systems in multiple organisms that many of the specific receptor families known to regulate cell fate decisions target conserved signaling pathways. A mechanism for preserving specificity in the cellular response that has emerged from these studies is one in which quantitative differences in receptor signaling regulate the cell fate decision. A signal strength model has recently gained support as a means to explain ,,/,, lineage commitment. In this review, we compare the ,,/,, fate decision with other cell fate decisions that occur outside of the lymphoid system to attain a better picture of the quantitative signaling mechanism for cell fate specification. [source] Transmembrane adapters: attractants for cytoplasmic effectorsIMMUNOLOGICAL REVIEWS, Issue 1 2003Jonathan A. Lindquist Summary: Transmembrane adapter proteins (TRAPs) are a relatively new and growing family of proteins that include linker for activation of T cells (LAT), phosphoprotein associated with glycosphingolipid-enriched micro domains (PAG)/C-terminal Src kinase (Csk) binding protein (Cbp), SHP2-interacting transmembrane adapter protein (SIT), T cell receptor interacting molecule (TRIM), and the recently identified non-T cell activation linker (NTAL) and pp30. TRAPs share several common structural features, but more importantly they possess multiple sites of tyrosine phosphorylation, by which they act as scaffolds for recruiting cytosolic adapter and/or effector proteins. The membrane association of TRAPs places them near to the immunoreceptors, a position from which they coordinate and modulate the signals they receive to produce an appropriate cellular response. [source] Favorable Modulation of Pre-Osteoblast Response to Nanograined/Ultrafine-grained Structures in Austenitic Stainless SteelADVANCED MATERIALS, Issue 12 2009R.D.K. Misra Nanograined (NG)/ultrafine-grained (UFG)structures show enhanced cellular response of pre-osteoblasts. Cell proliferation, viability, and morphology on phase-reversion annealed NG/UFG austenitic stainless steel were observed to be favorably modulated in comparison to conventional coarse-grained austenitic stainless steel. The improvement in cellular response is ascribed to NG/UFG structure and hydrophilicity of the cell substrate. [source] A High-Throughput Assay of Cell-Surface Interactions using Topographical and Chemical Gradients,ADVANCED MATERIALS, Issue 3 2009Jing Yang Orthogonal wettability and topographical gradients in a combinatorial sample format are fabricated using plasma-polymer-coated microgrooved surfaces. Preferred cell proliferation is found on specific combinations of topography and chemistry. This proof-of-concept study demonstrates the potential applications of this sample format for investigating the relationship between multiple surface properties on cellular response in a high-throughput manner. [source] Mismatch repair system decreases cell survival by stabilizing the tetraploid G1 arrest in response to SN-38INTERNATIONAL JOURNAL OF CANCER, Issue 12 2010Mandar Ramesh Bhonde Abstract The role of the mismatch repair (MMR) system in correcting base,base mismatches is well established; its involvement in the response to DNA double strand breaks, however, is less clear. We investigated the influence of the essential component of MMR, the hMLH1 protein, on the cellular response to DNA-double strand breaks induced by treatment with SN-38, the active metabolite of topoisomerase I inhibitor irinotecan, in a strictly isogenic cell system (p53wt, hMLH1+/p53wt, hMLH1,). By using hMLH1 expressing clones or cells transduced with the hMLH1-expressing adenovirus as well as siRNA technology, we show that in response to SN-38-induced DNA damage the MMR proficient (MMR+) cells make: (i) a stronger G2/M arrest, (ii) a subsequent longer tetraploid G1 arrest, (iii) a stronger activation of Chk1 and Chk2 kinases than the MMR deficient (MMR,) counterparts. Both Cdk2 and Cdk4 kinases contribute to the basal tetraploid G1 arrest in MMR+ and MMR, cells. Although the Chk1 kinase is involved in the G2/M arrest, neither Chk1 nor Chk2 are involved in the enhancement of the tetraploid G1 arrest. The long-lasting tetraploid G1 arrest of MMR+ cells is associated with their lower clonogenic survival after SN-38 treatment, the abrogation of the tetraploid G1 arrest resulted in their better clonogenic survival. These data show that the stabilization of the tetraploid G1 arrest in response to double strand breaks is a novel function of the MMR system that contributes to the lesser survival of MMR+ cells. [source] | |||||||||||||||||||||||||||||||||||||||||||