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Intracellular Signalling (intracellular + signalling)
Terms modified by Intracellular Signalling Selected AbstractsThe Ca2+ -dependent protein kinase CPK3 is required for MAPK-independent salt-stress acclimation in ArabidopsisTHE PLANT JOURNAL, Issue 3 2010Norbert Mehlmer Summary Plants use different signalling pathways to respond to external stimuli. Intracellular signalling via calcium-dependent protein kinases (CDPKs) or mitogen-activated protein kinases (MAPKs) present two major pathways that are widely used to react to a changing environment. Both CDPK and MAPK pathways are known to be involved in the signalling of abiotic and biotic stresses in animal, yeast and plant cells. Here, we show the essential function of the CDPK CPK3 (At4g23650) for salt stress acclimation in Arabidopsis thaliana, and test crosstalk between CPK3 and the major salt-stress activated MAPKs MPK4 and MPK6 in the salt stress response. CPK3 kinase activity was induced by salt and other stresses after transient overexpression in Arabidopsis protoplasts, but endogenous CPK3 appeared to be constitutively active in roots and leaves in a strictly Ca2+ -dependent manner. cpk3 mutants show a salt-sensitive phenotype comparable with mutants in MAPK pathways. In contrast to animal cells, where crosstalk between Ca2+ and MAPK signalling is well established, CPK3 seems to act independently of those pathways. Salt-induced transcriptional induction of known salt stress-regulated and MAPK-dependent marker genes was not altered, whereas post-translational protein phosphorylation patterns from roots of wild type and cpk3 plants revealed clear differences. A significant portion of CPK3 was found to be associated with the plasma membrane and the vacuole, both depending on its N -terminal myristoylation. An initial proteomic study led to the identification of 28 potential CPK3 targets, predominantly membrane-associated proteins. [source] The death of cardiotonic steroid-treated cells: evidence of Na+i,K+i -independent H+i -sensitive signallingACTA PHYSIOLOGICA, Issue 1-2 2006S. N. Orlov Abstract Na/K-ATPase is the only known target of cardiotonic steroids (CTS) identified in plants, amphibians and later on in several mammalian species, including human. We focus our review on recent data implicating CTS in the tissue-specific regulation of cell survival and death. In vascular smooth muscle cells, CTS inhibited cell death triggered by apoptotic stimuli via a novel Na+i -mediated, Ca2+i -independent mechanism of expression of antiapoptotic genes, including mortalin. In contrast, exposure to CTS in vascular endothelial and renal epithelial cells led to cell death, showing combined markers of apoptosis and necrosis. This mode of cell death, termed oncosis, is caused by CTS interaction with Na/K-ATPase but is independent of the inhibition of Na/K-ATPase-mediated ion fluxes and inversion of the [Na+]i/[K+]i ratio. The intermediates of intracellular signalling involved in Na+i, K+i -independent oncosis of CTS-treated cells remain unknown. Recently, we found that this mode of cell death can be protected by modest intracellular acidification via the expression of H+i -sensitive genes. The molecular origin of intracellular Na+ and H+ sensor involvement in the development of apoptosis and oncosis is currently under investigation. [source] Vascular smooth muscle cell phenotypic modulation in culture is associated with reorganisation of contractile and cytoskeletal proteinsCYTOSKELETON, Issue 3 2001Nathalie F. Worth Abstract Smooth muscle cells (SMC) exhibit a functional plasticity, modulating from the mature phenotype in which the primary function is contraction, to a less differentiated state with increased capacities for motility, protein synthesis, and proliferation. The present study determined, using Western analysis, double-label immunofluorescence and confocal microscopy, whether changes in phenotypic expression of rabbit aortic SMC in culture could be correlated with alterations in expression and distribution of structural proteins. "Contractile" state SMC (days 1 and 3 of primary culture) showed distinct sorting of proteins into subcellular domains, consistent with the theory that the SMC structural machinery is compartmentalised within the cell. Proteins specialised for contraction (,-SM actin, SM-MHC, and calponin) were highly expressed in these cells and concentrated in the upper central region of the cell. Vimentin was confined to the body of the cell, providing support for the contractile apparatus but not co-localising with it. In line with its role in cell attachment and motility, ,-NM actin was localised to the cell periphery and basal cortex. The dense body protein ,-actinin was concentrated at the cell periphery, possibly stabilising both contractile and motile apparatus. Vinculin-containing focal adhesions were well developed, indicating the cells' strong adhesion to substrate. In "synthetic" state SMC (passages 2,3 of culture), there was decreased expression of contractile and adhesion (vinculin) proteins with a concomitant increase in cytoskeletal proteins (,-non-muscle [NM] actin and vimentin). These quantitative changes in structural proteins were associated with dramatic changes in their distribution. The distinct compartmentalisation of structural proteins observed in "contractile" state SMC was no longer obvious, with proteins more evenly distributed throughout the cytoplasm to accommodate altered cell function. Thus, SMC phenotypic modulation involves not only quantitative changes in contractile and cytoskeletal proteins, but also reorganisation of these proteins. Since the cytoskeleton acts as a spatial regulator of intracellular signalling, reorganisation of the cytoskeleton may lead to realignment of signalling molecules, which, in turn, may mediate the changes in function associated with SMC phenotypic modulation. Cell Motil. Cytoskeleton 49:130,145, 2001. © 2001 Wiley-Liss, Inc. [source] Vitamin D and calcium deficits predispose for multiple chronic diseasesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2005M. Peterlik Abstract There is evidence from both observational studies and clinical trials that calcium malnutrition and hypovitaminosis D are predisposing conditions for various common chronic diseases. In addition to skeletal disorders, calcium and vitamin D deficits increase the risk of malignancies, particularly of colon, breast and prostate gland, of chronic inflammatory and autoimmune diseases (e.g. insulin-dependent diabetes mellitus, inflammatory bowel disease, multiple sclerosis), as well as of metabolic disorders (metabolic syndrome, hypertension). The aim of the present review was to provide improved understanding of the molecular and cellular processes by which deficits in calcium and vitamin D cause specific changes in cell and organ functions and thereby increase the risk for chronic diseases of different aetiology. 1,25-dihydroxyvitamin D3 and extracellular Ca++ are both key regulators of proliferation, differentiation and function at the cellular level. However, the efficiency of vitamin D receptor-mediated intracellular signalling is limited by the negative effects of hypovitaminosis D on extrarenal 25-hydroxyvitamin D-1,-hydroxylase activity and thus on the production of 1,25-dihydroxyvitamin D3. Calcium malnutrition eventually causes a decrease in calcium concentration in extracellular fluid compartments, resulting in organ-specific modulation of calcium-sensing receptor activity. Hence, attenuation of signal transduction from the ligand-activated vitamin D receptor and calcium-sensing receptor seems to be the prime mechanism by which calcium and vitamin D insufficiencies cause perturbation of cellular functions in bone, kidney, intestine, mammary and prostate glands, endocrine pancreas, vascular endothelium, and, importantly, in the immune system. The wide range of diseases associated with deficits in calcium and vitamin D in combination with the high prevalence of these conditions represents a special challenge for preventive medicine. [source] Aberrant signalling and transcription factor activation as an explanation for the defective growth control and differentiation of keratinocytes in psoriasis: a hypothesisEXPERIMENTAL DERMATOLOGY, Issue 4 2003R. C. McKenzie Abstract:, Psoriasis is a chronic inflammatory skin disease characterized by the accumulation of red, scaly plaques on the skin. The plaques result from hyperproliferation and incomplete differentiation of keratinocytes (KC) in a process that seems to be driven, in part by skin-infiltrating leucocytes. We believe that the KC have inherent defects in intracellular signalling which could be usefully targeted to allow the development of more effective therapies. We suggest that there are defects in the regulation of the transcription factors: signal transducer and activator of transcription (STAT-1,), interferon regulated factor-1 (IRF-1) and NF,B which lead to loss of growth and differentiation control when the cells are subjected to physico-chemical and immunological stress. We also highlight recent studies that suggest that peroxisome proliferator-activated receptors, the notch receptor and defects in calcium and other ion transporting proteins may contribute to impairment in the ability of psoriatic KC to differentiate. The role of these systems in the development of the psoriatic phenotype and tests of these hypotheses are proposed. [source] Growth hormone excess and the development of growth hormone receptor antagonistsEXPERIMENTAL PHYSIOLOGY, Issue 11 2008C. E. Higham In 1990, a single amino acid substitution in the growth hormone (GH) gene at position 119 was found to transform the consequent protein from an agonist to an antagonist at the growth hormone receptor (GHR). Further amino acid substitutions plus prolongation of the half-life of the protein by pegylation resulted in the first clinically effective GHR antagonist, pegvisomant. Following extensive clinical trials, this medication has emerged as the most efficacious therapy for treatment-resistant acromegaly. Subsequent advances in our understanding of GH,GHR interactions and downstream GH signalling pathways suggest that pegvisomant binds to preformed GHR dimers and prevents rotational changes within the receptor,GH complex necessary for intracellular signalling to occur. This article reviews the discovery of pegvisomant, from initial experimental data to successful licensing of the drug for treatment-resistant acromegaly, and discusses its other potential therapeutic uses in diseases with abnormalities in the GH,IGF-I axis. [source] Regulation of T-cell receptor signalling by membrane microdomainsIMMUNOLOGY, Issue 4 2004Tahir M. Razzaq Summary There is now considerable evidence suggesting that the plasma membrane of mammalian cells is compartmentalized by functional lipid raft microdomains. These structures are assemblies of specialized lipids and proteins and have been implicated in diverse biological functions. Analysis of their protein content using proteomics and other methods revealed enrichment of signalling proteins, suggesting a role for these domains in intracellular signalling. In T lymphocytes, structure/function experiments and complementary pharmacological studies have shown that raft microdomains control the localization and function of proteins which are components of signalling pathways regulated by the T-cell antigen receptor (TCR). Based on these studies, a model for TCR phosphorylation in lipid rafts is presented. However, despite substantial progress in the field, critical questions remain. For example, it is unclear if membrane rafts represent a homogeneous population and if their structure is modified upon TCR stimulation. In the future, proteomics and the parallel development of complementary analytical methods will undoubtedly contribute in further delineating the role of lipid rafts in signal transduction mechanisms. [source] C-terminal 37 residues of LRP promote the amyloidogenic processing of APP independent of FE65JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 6b 2008Madepalli K. Lakshmana Abstract The major defining pathological hallmark of Alzheimer's disease (AD) is the accumulation of amyloid , protein (A,), a small peptide derived from ,- and ,-secretase cleavages of the amyloid precursor protein (APP). Recent studies have shown that the Low-density lipoprotein receptor-related protein (LRP) plays a pivotal role in the trafficking of APP and generation of A,. In particular, we recently showed that the soluble cytoplasmic tail of LRP (LRP-ST) without a membrane tether was sufficient to promote A, generation. In this study, we demonstrate that the last 37 residues of LRP cytoplasmic tail (LRP-C37) lacking the NPxY motifs and FE65 binding mediate the core pro-amyloidogenic activity of LRP-ST. Moreover, we show that the conserved dileucine motif within the LRP-C37 region is a key determinant of its A, promoting activity. Finally, results from a yeast two-hybrid screen using LRP-C37 region as bait reveal four new LRP-binding proteins implicated in intracellular signalling and membrane protein trafficking. Our findings indicate that the LRP-C37 sequence represents a new protein-binding domain that may be useful as a therapeutic target and tool to lower A, generation in AD. [source] Vasomotion dynamics following calcium spiking depend on both cell signalling and limited constriction velocity in rat mesenteric small arteriesJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2008Ed VanBavel Abstract Vascular smooth muscle cell contraction depends on intracellular calcium. However, calcium-contraction coupling involves a complex array of intracellular processes. Quantitating the dynamical relation between calcium perturbations and resulting changes in tone may help identifying these processes. We hypothesized that in small arteries accurate quantitation can be achieved during rhythmic vasomotion, and questioned whether these dynamics depend on intracellular signalling or physical vasoconstriction. We studied calcium-constriction dynamics in cannulated and pressurized rat mesenteric small arteries (,300 ,m in diameter). Combined application of tetra-ethyl ammonium (TEA) and BayK8644 induced rhythmicity, consisting of regular and irregular calcium spiking and superposition of spikes. Calcium spikes induced delayed vasomotion cycles. Their dynamic relation could be fitted by a linear second-order model. The dirac impulse response of this model had an amplitude that was strongly reduced with increasing perfusion pressure between 17 and 98 mmHg, while time to peak and relaxation time were the largest at an intermediate pressure (57 mmHg: respectively 0.9 and 2.3 sec). To address to what extent these dynamics reside in intracellular signalling or vasoconstriction, we applied rhythmic increases in pressure counteracting the vasoconstriction. This revealed that calcium-activation coupling became faster when vasoconstriction was counteracted. During such compensation, a calcium impulse response remained that lasted 0.5 sec to peak activation, followed by a 1.0 sec relaxation time, attributable to signalling dynamics. In conclusion, this study demonstrates the feasibility of quantitating calcium-activation dynamics in vasomoting small arteries. These dynamics relate to both intracellular sig-nalling and actual vasoconstriction. Performing such analyses during pharmacological intervention and in genetic models provides a tool for unravelling calcium-contraction coupling in small arteries. [source] What can we learn from tuberous sclerosis complex (TSC) about autism?JOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 10 2008P. J. De Vries Tuberous Sclerosis Complex (TSC) is now recognized as one of the medical conditions most commonly associated with autism. Between 1,5% of those with autism have TSC and up to 50% of people with TSC meet criteria for an autism spectrum disorder. The clinical characteristics of autism in TSC are qualitatively indistinguishable from those of idiopathic autism. So, what can TSC teach us about autism? We will present an overview of the neuropsychiatric features of TSC and will proceed with an examination of aetiological models of autism in TSC. Structural models (suggesting that autism is caused by brain lesions in specific neuroanatomical locations) and seizure models (suggesting that the age, type and control of seizures may predict autism) have both received some support, but with limited replication. More recently, molecular approaches have suggested that dysregulation of intracellular signalling through the TSC1/2-mTOR pathway may be sufficient to lead to socialization deficits and autism, and that drugs that act as mTOR inhibitors may reverse some aspects of the learning and social deficits in TSC. [source] Kin1 is a plasma membrane-associated kinase that regulates the cell surface in fission yeastMOLECULAR MICROBIOLOGY, Issue 5 2010Angela Cadou Summary Cell morphogenesis is a complex process that depends on cytoskeleton and membrane organization, intracellular signalling and vesicular trafficking. The rod shape of the fission yeast Schizosaccharomyces pombe and the availability of powerful genetic tools make this species an excellent model to study cell morphology. Here we have investigated the function of the conserved Kin1 kinase. Kin1-GFP associates dynamically with the plasma membrane at sites of active cell surface remodelling and is present in the membrane fraction. Kin1, null cells show severe defects in cell wall structure and are unable to maintain a rod shape. To explore Kin1 primary function, we constructed an ATP analogue-sensitive allele kin1-as1. Kin1 inhibition primarily promotes delocalization of plasma membrane-associated markers of actively growing cell surface regions. Kin1 itself is depolarized and its mobility is strongly reduced. Subsequently, amorphous cell wall material accumulates at the cell surface, a phenotype that is dependent on vesicular trafficking, and the cell wall integrity mitogen-activated protein kinase pathway is activated. Deletion of cell wall integrity mitogen-activated protein kinase components reduces kin1, hypersensitivity to stresses such as those induced by Calcofluor white and SDS. We propose that Kin1 is required for a tight link between the plasma membrane and the cell wall. [source] Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young menTHE JOURNAL OF PHYSIOLOGY, Issue 21 2009Daniel W. D. West We aimed to determine whether exercise-induced elevations in systemic concentration of testosterone, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) enhanced post-exercise myofibrillar protein synthesis (MPS) and phosphorylation of signalling proteins important in regulating mRNA translation. Eight young men (20 ± 1.1 years, BMI = 26 ± 3.5 kg m,2) completed two exercise protocols designed to maintain basal hormone concentrations (low hormone, LH) or elicit increases in endogenous hormones (high hormone, HH). In the LH protocol, participants performed a bout of unilateral resistance exercise with the elbow flexors. The HH protocol consisted of the same elbow flexor exercise with the contralateral arm followed immediately by high-volume leg resistance exercise. Participants consumed 25 g of protein after arm exercise to maximize MPS. Muscle biopsies and blood samples were taken as appropriate. There were no changes in serum testosterone, GH or IGF-1 after the LH protocol, whereas there were marked elevations after HH (testosterone, P < 0.001; GH, P < 0.001; IGF-1, P < 0.05). Exercise stimulated a rise in MPS in the biceps brachii (rest = 0.040 ± 0.007, LH = 0.071 ± 0.008, HH = 0.064 ± 0.014% h,1; P < 0.05) with no effect of elevated hormones (P= 0.72). Phosphorylation of the 70 kDa S6 protein kinase (p70S6K) also increased post-exercise (P < 0.05) with no differences between conditions. We conclude that the transient increases in endogenous purportedly anabolic hormones do not enhance fed-state anabolic signalling or MPS following resistance exercise. Local mechanisms are likely to be of predominant importance for the post-exercise increase in MPS. [source] Metal-free MIRAS phasing: structure of apo-S100A3ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2002Peer R. E. Mittl S100 proteins are involved in metal-dependent intracellular signalling. Metal-free S100A3, a cysteine-rich Ca2+ - and Zn2+ -binding protein, has been crystallized by vapour diffusion under the strict exclusion of oxygen and in the absence of divalent metal ions. Metal binding induces large conformational changes, rendering the apo-S100A3 crystals very sensitive to various metal compounds. Therefore, the structure was solved by MIRAS phasing using potassium iodide and xenon derivatives. Iodide replaces a water molecule at the surface of the S100A3 protein, whereas xenon binds in a hydrophobic cavity at the dimer interface. Despite significant non-isomorphism, the combination of both derivatives was sufficient for structure determination. The overall apo-S100A3 structure resembles the structures of metal-free S100B and S100A6 solution structures. In contrast to the NMR structures, the EF-hand loops are well ordered in the apo-S100A3 crystal structure. In the N-terminal pseudo-EF-hand loop a water molecule occupies the position of the Ca2+ ion. The C-terminal canonical EF-hand loop shows an extended conformation and a different helix arrangement to other S100/metal complex crystal structures. [source] Gase als zelluläre Signalstoffe.BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 3 2010Gasotransmitter Abstract Die Gase Stickoxid (NO), Kohlenmonoxid (CO) und Schwefelwasserstoff (H2S) werden aufgrund ihrer Wirkung als Signalstoffe als "Gasotransmitter" zusammengefasst. Diese Gase spielen eine wichtige Rolle als intra- und interzellulärer Signalstoff im Verdauungs-, Atmungs- oder Urogenitalsystem, bei der Steuerung des Herzschlags oder Nervenaktivitäten. Die Forschung ist dabei, Funktionen und weitere Details der Wirkmechanismen dieser Gase und ihre Implikationen für Physiologie, Pathophysiologie und Pharmakologie zu erarbeiten. Vom bisher neuesten Kandidaten , dem H2S , gibt es Hinweise, dass er in hoher Konzentration im Gehirn und in den Hoden vorkommt und bei Lern-/Gedächtnisprozessen sowie bei Geschlechtsfunktionen eine Rolle spielt. Durch Entwicklung von Wirksubstanzen zur Beeinflussung der H2S-Produktion oder entsprechender Zielorte könnte sich hieraus ein interessantes pharmakologisches Potenzial entwickeln. Gasotransmitters , gases as cellular signalling molecules The gases nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H2S) because of their capacity as signalling molecules have been now collectively termed "gasotransmitters". These gases play an important role in inter- and intracellular signalling, as in the digestive, respiratory or urogenital tract, in controlling heart activity or in nerve function. Research now tries to work out functions and further details about the mechanism of action of these gases and their implications for physiology, pathophysiology and pharmacology. The most recent candidate, H2S, is found in high concentrations in the brain and in the testis and hence is involved in learning/memory and in reproductive functions. The development of new substances interfering with the production of H2S or its targets may constitute an interesting pharmacological potential. [source] Cigarette smoke suppresses in vitro allergic activation of mouse mast cellsCLINICAL & EXPERIMENTAL ALLERGY, Issue 5 2009E. Mortaz Summary Background Mast cells are important effector cells in innate or acquired immunity that contribute to host defence. Excessive activation of mast cells can result in the development of allergic diseases, including atopic asthma. Mast cell activation by IgE and specific antigen induces the cells to release spasmogenic, vasoactive and pro-inflammatory mediators, which enhance airway smooth muscle contraction, vascular permeability and inflammatory cell recruitment. Recently, we have demonstrated that exposure of mast cells to cigarette smoke medium (CSM) triggered mast cells to produce chemokines. On the other hand, smoking may decrease the risk of allergic sensitization, which could be explained by a reduced IgE production or a diminished response of mast cells to activation of the IgE receptor. Objective In this study, we investigated the effect of CSM on the allergic activation of mast cells through IgE and antigen. Methods Primary cultured murine mast cells were exposed to CSM and activated with IgE and antigen or lipopolysaccharide (LPS). The release of granules, production of leukotrienes, chemokines and cytokines was determined in the supernatants by ELISA. The effect of CSM exposure on intracellular signalling, especially the nuclear factor (NF)-,B and extracellular signal-regulated kinase (Erk)1/2 pathways, was analysed by Western blotting. Results CSM suppressed IgE-mediated degranulation and cytokine release, but no effect was observed on leukotriene release. CSM induced phosphorylation of Erk1/2 in mast cells. In CSM-exposed mast cells, activating transcription factor (ATF)-1 was phosphorylated after stimulation with IgE/Ag. LPS-activated mast cells were not influenced by CSM. Conclusion Our study suggests that exposure to cigarette smoke may lead to a reduced allergic activation of mast cells without affecting their response to activation via e.g. bacterial-derived LPS. [source] Combined analysis of intracellular signalling and immunophenotype of human peripheral blood basophils by flow cytometry: a proof of conceptCLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2007D. G. Ebo Summary Background The signal transduction pathways and control mechanisms involved in IgE-mediated basophil activation remain incompletely understood. Objectives To investigate whether basophilic intracellular signal transduction and immunophenotype can be analysed simultaneously by flow cytometry. Methods Basophils in whole blood were stimulated with anti-IgE and latex antigen at various concentrations and during different time courses. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) as a representative of the intracellular signal transduction pathway and surface expression of CD63 was assessed simultaneously flow cytometrically. The effect of pre-incubation with IL-3 was assessed. Results Stimulation of the basophils with anti-IgE and allergen induces a rapid phosphorylation of p38 MAPK that peaks between 1 and 5 min and returns to baseline levels after 60 min. In contrast, CD63 up-regulation demonstrates a maximal but more continuous expression that peaks approximately 5 min later than phosphorylation of p38 MAPK. Specific inhibition of p38 MAPK reduced or almost completely abrogated up-regulation of CD63. Pre-incubation of the basophils with IL-3 produces a rapid p38 MAPK phosphorylation over basal levels, but this was weaker and shorter than for anti-IgE stimulation. Pre-incubation of the basophils with IL-3 did not potentiate anti-IgE-induced phosphorylation of p38 MAPK and did affect spontaneous or IgE-mediated CD63 up-regulation. Conclusions This study provides the proof that the flow cytometer allows an integrated analysis of basophilic intracellular signalling and immunophenotyping. Owing to its technical simplicity, the low number of cells required and rapid analysis, the technique seems promising for use in the clinic as a diagnostic tool or to monitor therapy. Capsule summary This study is the first to provide evidence for a combined analysis of basophilic intracellular signalling and immunophenotyping by flow cytometry. Owing to its technical simplicity, the low number of cells required and rapid analysis, the technique seems promising for use in the clinic as a diagnostic tool or to monitor therapy. [source] Traditional therapies: glucocorticoids, azathioprine, methotrexate, hydroxyureaCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 7 2002G. Belgi Summary The ,old favourites' used for treatment of inflammatory diseases, and hence, the original immunomodulators, include the glucocorticoids, azathioprine, methotrexate and hydroxyurea. Glucocorticoids are still one of the most effective anti-inflammatory agents because they work on several different intracellular processes and hence, block many components that contribute to inflammatory and immune responses. They bind to intracellular glucocorticoid receptors which transport them into the nucleus. Here the receptor/steroid complex may bind to many genes that interact with transcription factors including NF,B and AP-1, to inhibit their activation, thereby preventing activation of many genes encoding immune effector and pro-inflammatory cytokines. Also, protein kinases involved in intracellular signalling, are directly activated resulting in phosphorylation of various targets of which Annexin (AXA)-1 is critical in inhibiting biosynthesis of both purines and DNA. This results in reduced proliferation of B and T lymphocytes, reduced immune effector mechanisms and reduced recruitment of mononuclear cells including monocytes into sites of immune inflammation. Methotrexate also blocks DNA synthesis and hence cellular proliferation but also induces release of adenosine. This inhibits chemotaxis of polymorph neutrophils and release of critical cytokines such as TNF-, and Interleukins 6 and 8. Hydroxyurea also inhibits DNA synthesis with inhibitory effects on proliferation of lymphocytes and possibly kerationcytes. Even though many new agents with much greater selectivity are coming through into clinical use, this group of old agents still have an absolutely central position in the therapeutic armamentarium. Their value lies in the fact that they are not ,clean' drugs with narrow effects but they inhibit a wide range of mechanisms involved in immune and inflammatory processes. [source] MODULATION OF SIGNAL TRANSDUCERS AND ACTIVATORS OF TRANSCRIPTION (STAT) FACTOR PATHWAYS DURING FOCAL CEREBRAL ISCHAEMIA: A GENE EXPRESSION ARRAY STUDY IN RAT HIPPOCAMPUS AFTER MIDDLE CEREBRAL ARTERY OCCLUSIONCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007Sheng-Li Sun SUMMARY 1Signal transducers and activators of transcription (STAT) factors are a family of transcription factors that mediate intracellular signalling initiated at cytokine cell surface receptors and transmitted to the nucleus. In the present study, we determined the global changes in STAT gene expression in the hippocampus of rats after focal cerebral ischaemia and reperfusion using microarray analysis. 2The present study used middle cerebral artery occlusion (MCAO) to induce ischaemia and reperfusion in Sprague-Dawley rats. Using superarray Q series Janus tyrosine kinases (Jak)/STAT signalling pathway gene array, a total of 96 genes was screened in adult male rat hippocampus after transient focal cerebral ischaemia. 3The results showed that 23 genes were upregulated at least twofold by ischaemia treatment and that 12 genes were downregulated at least threefold by ischaemia treatment compared with controls. 4After confirmation by quantitative real-time polymerase chain reaction, the data suggest that the gene expression of STAT2, 5a, 5b, 6 and suppressor of cytokine signalling (SOCS) 4 was increased by ischaemia, probably due to a compensatory response of the brain, which may play a protective role in damaged brain tissue. 5The results of the present study provide evidence on global changes in STAT gene expression in the hippocampus of rats after focal cerebral ischaemia and reperfusion, in which STAT2, 5a, 5b, 6 and SOCS4 were confirmed to be significantly modulated during focal cerebral ischaemia. 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