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Factor Activation (factor + activation)
Kinds of Factor Activation Selected AbstractsMisregulation of gene expression in the redox-sensitive NF-,b-dependent limb outgrowth pathway by thalidomideDEVELOPMENTAL DYNAMICS, Issue 2 2002Jason M. Hansen Abstract Thalidomide is known to induce oxidative stress, but mechanisms have not been described through which oxidative stress could contribute to thalidomide-induced terata. Oxidative stress modulates intracellular glutathione (GSH) and redox status and can perturb redox-sensitive processes, such as transcription factor activation and/or binding. Nuclear factor-kappa B (NF-,B), a redox-sensitive transcription factor involved in limb outgrowth, may be modulated by thalidomide-induced redox shifts. Thalidomide-resistant Sprague-Dawley rat embryos (gestation day [GD] 13) treated with thalidomide in utero showed no changes in GSH distribution in the limb but thalidomide-sensitive New Zealand White rabbit embryos (GD 12) showed selective GSH depletion in the limb bud progress zone (PZ). NF-,B and regulatory genes that initiate and maintain limb outgrowth and development, such as Twist and Fgf-10, are selectively expressed in the PZ. Green fluorescent protein (GFP) reporter vectors containing NF-,B binding promoter sites were transfected into both rat and rabbit limb bud cells (LBCs). Treatment with thalidomide caused a preferential decrease in GFP expression in rabbit LBCs but not in rat LBCs. N-acetylcysteine and ,-N-t-phenylbutyl nitrone (PBN), a free radical trapping agent, rescued GFP expression in thalidomide-treated cultures compared with cultures that received thalidomide only. In situ hybridization showed a preferential decrease in Twist, Fgf-8, and Fgf-10 expression after thalidomide treatment (400 mg/kg per day) in rabbit embryos. Expression in rat embryos was not affected. Intravenous cotreatment with PBN and thalidomide (gavage) in rabbits restored normal patterns and localization of Twist, Fgf-8, and Fgf-10 expression. These findings show that NF-,B binding is diminished due to selective thalidomide-induced redox changes in the rabbit, resulting in the significant attenuation of expression of genes necessary for limb outgrowth. © 2002 Wiley-Liss, Inc. [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] Alcoholic fatty liver differentially induces a neutrophil-chemokine and hepatic necrosis after ischemia-reperfusion in ratHEPATOLOGY, Issue 2 2000Shinwa Yamada M.D. Primary graft nonfunction of steatotic liver allograft is one of the factors causing shortage of donor livers. Ischemia/reperfusion (I/R) injury is an important contributory factor to primary graft nonfunction. In this study, we investigated the complex chain of events from transcription factor activation to necrosis through cytokine induction and apoptosis in steatotic rat liver after warm I/R. Rats with alcoholic or nonalcoholic fatty liver were subjected to hepatic warm I/R and compared with control rats. Rats fed an ethanol diet for 6 to 8 weeks developed severe hepatic necrosis accompanied by increased neutrophil recruitment after I/R, compared with rats with nonalcoholic fatty liver or control. Hepatic apoptosis as assessed by DNA fragmentation at 4 hours after I/R, however, increased to a similar degree in each of the 2 fatty liver models compared with the control. Alcoholic fatty liver exposed to I/R showed a rapid increase in nuclear factor-,B (NF-,B) binding activity at 1 hour after I/R, which preceded an increased expression of tumor necrosis factor , (TNF-,) and cytokine-induced neutrophil chemoattractant-1 (CINC-1). In contrast, nonalcoholic fatty liver did not show such potentiation of either NF-,B activation or cytokine induction after I/R. Our results have indicated that alcoholic fatty liver may differentially induce CINC-1 production and hepatic necrosis after I/R. Furthermore, our results suggest that apoptosis per se does not always lead to necrosis in the liver following I/R. [source] Nucleosomes activate NF-,B in endothelial cells for induction of the proangiogenic cytokine IL-8INTERNATIONAL JOURNAL OF CANCER, Issue 1 2004Jerome E. Tanner Abstract Solid tumors often exhibit regions undergoing apoptosis and necrosis, also referred to as "aponecrosis", juxtaposed to sites of active angiogenesis. We explored whether nucleosomes resulting from aponecrosis induced the angiogenic factor IL-8 in vascular endothelial cells. Results indicate that nucleosomes induced IL-8. Nucleosomes increased IL-6 and IL-8 mRNA but not IL-10, TNF-,, VEGF or FGF-2 mRNA. Induction of IL-8 by nucleosomes in endothelial cells appeared to be the result of NF-,B/RelA transcription factor activation. The increased expression of IL-8 in vascular endothelial cells following nucleosome stimulation suggests that aponecrosis could play an important role in the promotion of tumor angiogenesis. © 2004 Wiley-Liss, Inc. [source] Hypoxia-inducible factor and nuclear factor kappa-B activation in blood,brain barrier endothelium under hypoxic/reoxygenation stressJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Ken A. Witt Abstract This investigation focuses on transcription factor involvement in blood,brain barrier (BBB) endothelial cell-induced alterations under conditions of hypoxia and post-hypoxia/reoxygenation (H/R), using established in vivo/ex vivo and in vitro BBB models. Protein/DNA array analyses revealed a correlation in key transcription factor activation during hypoxia and H/R, including NF,B and hypoxia-inducible factor (HIF)1. Electrophoretic mobility shift assays confirmed NF,B and HIF1 binding activity ex vivo and in vitro, under conditions of hypoxia and H/R. Hypoxia- and H/R-treated BBB endothelium showed increased HIF1, protein expression in both cytoplasmic and nuclear fractions, in ex vivo and in vitro models. Co-immunoprecipitation of HIF1, and HIF1, was shown in the nuclear fraction under conditions of hypoxia and H/R in both models. Hypoxia- and H/R-treated BBB endothelium showed increased expression of NF,B-p65 protein in both cytoplasmic and nuclear fractions. Co-immunoprecipitation of NF,B-p65 with NF,B-p50 was shown in the nuclear fraction under conditions of hypoxia and H/R in the ex vivo model, and after H/R in the in vitro model. These data offer novel avenues in which to alter and/or investigate BBB activity across model systems and to further our understanding of upstream regulators during hypoxia and H/R. [source] Activation Of Mitogen Activated Protein Kinases (Mapks) In Response To High Glucose In Primary Sensory NeuronesJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000T Purves In diabetes high glucose stresses cells as a prelude to complications. The MAPKs are serine-threonine kinases, which are putative glucose stress transducers, comprising extracellular signal regulated kinases (ERKs), p38 and c-Jun, n-terminal kinases (JNKs). In 10 week streptozotocin-induced diabetic rats JNK activation was increased when compared to age matched controls. This study aimed to determine the signaling pathways activated in response to high glucose in adult sensory neurones in vitro. Cultures of adult rat dorsal root ganglia (DRG) were treated with 10mM, 25mM and 50mM glucose for 16 hours. MAPK activation was examined in Western blots using antibodies raised against phosphorylated and non-phosphorylated epitopes (results expressed as a ratio of phosphorylated to non-phosphorylated kinase). Glucose caused a concentration-dependent increase in phospho-p38 with a 1.6 fold increase at 25mM (0.77 ± 1.04) and a 2.4 fold increase at 50mM (1.18 ± 1.44) when compared to 10mM (0.49 ± 0.60) glucose. Phosphorylation of the p56 JNK isoform increased 2.4 fold (4.37 ± 3.59) and the p46 isoform 2.2 fold (1.95 ± 1.35) at 50mM glucose when compared to 10mM (p56 1.80 ± 0.99, p46 0.88 ± 0.31). ERK phosphorylation remained unchanged in 3 different experiments. Immunocytochemistry located these changes to neurones, rather than the small percentage of non-neurones that remain in culture. Transcription factor activation as a result of MAPK activation is being investigated using electrophoretic mobility shift assays. We conclude that the activation of MAPK pathways is involved in the response of neuronal cells to high glucose stress. [source] von Willebrand factor activation, granzyme-B and thrombocytopenia in meningococcal diseaseJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2010M. J. HOLLESTELLE Summary.,Background:,During invasive meningococcal disease, severe thrombocytopenia is strongly associated with a poor outcome. Objectives:,In order to elucidate the pathophysiological mechanism behind the development of thrombocytopenia, we studied the role of von Willebrand factor (VWF) in meningococcal disease. Patients/methods:,Thirty-two children with severe meningococcal disease admitted to our university hospital were included in this study. VWF and related parameters were measured and results were correlated with the development of shock and thrombocytopenia. Results:,At admission, all patients had increased levels of (active) VWF and VWF propeptide. The highest VWF propeptide levels were observed in patients with shock, indicating acute endothelial activation. Although VWF propeptide levels in patients with shock, with or without thrombocytopenia, were similar, increased active VWF was significantly lower in patients with thrombocytopenia as compared with patients without thrombocytopenia. ADAMTS13 was moderately decreased. However, the VWF multimeric pattern was minimally increased. We assume that these findings are explained by VWF consumption and perhaps by granzyme B (GrB). In vitro experiments showed that GrB is able to cleave VWF multimers in plasma, whereas GrB was high in patients with shock, who developed thrombocytopenia. Conclusions:,Our results demonstrate that consumption of VWF, derived from endothelial cells, could be a key feature of meningococcal disease and primary to the development of thrombocytopenia during shock. [source] Clinical measurement of thrombin generation by calibrated automated thrombography requires contact factor inhibitionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2004R. Luddington Summary.,Background: Measurement of thrombin generation by calibrated automated thrombography (CAT) could fulfill the requirements of a global test of coagulability and is potentially applicable to routine clinical laboratory practice. The purpose of this study was to determine if corn trypsin inhibitor (CTI) could be used to abolish contact factor activation in this assay, thus allowing accurate measurement of low tissue factor (TF) concentration-triggered thrombin generation on samples taken in a routine clinical setting. Methods: The endogenous thrombin potential (ETP) was measured by CAT. Results: The study demonstrated that addition of CTI after plasma separation is not sufficient and blood must be drawn into tubes containing CTI if in-vitro contact factor-activated thrombin generation is to be abolished. Contact factor-activated thrombin generation is completely inhibited at a CTI concentration of 18.3 µg mL,1 whole blood. Increasing the CTI concentration above this level does not lead to suppression of the TF-triggered ETP. At a TF concentration of 2 pmol, ETPs were significantly lower in the presence of CTI (P < 0.001). The difference (no CTI minus CTI) between results ranged from ,,1 to 2159 nM min,1 (median ,,754). Whilst the low concentration TF-ETP assay was not optimized to distinguish degrees of coagulability between patient samples, there was a significant difference in ETP between normal and hemophilia samples and samples from patients with a clinical prothrombotic tendency. Conclusions: CTI can be applied to ETP measurement by CAT. This permits the use of CAT in a low TF-triggered thrombin generation assay without concern for the effect of interference from in-vitro contact factor activation and the optimum reagent conditions for using CAT as a global test of coagulability in clinical practice can now be defined. [source] 4-Methylumbelliferone inhibits tumour cell growth and the activation of stromal hyaluronan synthesis by melanoma cell-derived factorsBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2010M. Edward Summary Background, There is a close correlation between tumour progression and hyaluronan production, either by tumour cells or by stromal cells that are stimulated by tumour-derived factors. Inhibition of tumour stimulation of fibroblast hyaluronan may suppress tumour growth and invasion. Objectives, To examine the effect of the hyaluronan synthesis inhibitor 4-methylumbelliferone (4-MU) on the growth of and hyaluronan synthesis by fibroblasts and C8161 and MV3 melanoma cell lines, invasion, and inhibition of tumour cell-derived factor activation of fibroblasts. Methods, Effects of 4-MU on growth and hyaluronan synthesis by fibroblasts and melanoma cells were examined in monolayer culture and fibroblast-contracted collagen lattices, and their effects on the growth and invasion of tumour cells into collagen lattices were also studied. Results, 4-MU caused a dose-dependent growth inhibition of fibroblast and melanoma cells with maximum inhibition at 0·5 mmol L,1 4-MU. At this dose, 4-MU inhibited 3H-glucosamine incorporation into fibroblast glycosaminoglycans by 52%, and hyaluronan synthesis by 64%. The relative inhibition was more pronounced when fibroblasts were stimulated with C8161 melanoma cell-conditioned medium. 4-MU reduced the level of hyaluronan in fibroblast-contracted collagen lattices, and inhibited both the growth on and invasion into the lattices by melanoma cells. This growth inhibition appears to be predominantly independent of inhibition of hyaluronan synthesis. The effect on growth inhibition was reversible, and 4-MU had no effect on apoptosis. Conclusions, 4-MU is a potent inhibitor of hyaluronan synthesis, induction of stromal hyaluronan accumulation by tumour cells, and fibroblast and melanoma cell proliferation, and results suggest that 4-MU may have potential as a tumour cell anti-invasive and antiproliferative agent. [source] | |||||||||||||