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Cellular Inhibitor (cellular + inhibitor)
Selected Abstracts,-Fetoprotein positively regulates cytochrome c -mediated caspase activation and apoptosome complex formationFEBS JOURNAL, Issue 21 2003Lidia Semenkova Previous results have shown that the oncoembryonic marker ,-fetoprotein (AFP) is able to induce apoptosis in tumor cells through activation of caspase 3, bypassing Fas-dependent and tumor necrosis factor receptor-dependent signaling. In this study we further investigate the molecular interactions involved in the AFP-mediated signaling of apoptosis. We show that AFP treatment of tumor cells is accompanied by cytosolic translocation of mitochondrial cytochrome c. In a cell-free system, AFP mediates processing and activation of caspases 3 and 9 by synergistic enhancement of the low-dose cytochrome c -mediated signals. AFP was unable to regulate activity of caspase 3 in cell extracts depleted of cytochrome c or caspase 9. Using high-resolution chromatography, we show that AFP positively regulates cytochrome c/dATP-mediated apoptosome complex formation, enhances recruitment of caspases and Apaf-1 into the complex, and stimulates release of the active caspases 3 and 9 from the apoptosome. By using a direct protein,protein interaction assay, we show that pure human AFP almost completely disrupts the association between processed caspases 3 and 9 and the cellular inhibitor of apoptosis protein (cIAP-2), demonstrating its release from the complex. Our data suggest that AFP may regulate cell death by displacing cIAP-2 from the apoptosome, resulting in promotion of caspase 3 activation and its release from the complex. [source] The role of neutrophil apoptosis in juvenile-onset systemic lupus erythematosusARTHRITIS & RHEUMATISM, Issue 8 2009Angela Midgley Objective Accumulation of apoptotic cells may lead to the development of systemic lupus erythematosus (SLE) through a breakdown in immune tolerance. Altered neutrophil apoptosis may contribute to nuclear autoantigen exposure, ultimately leading to autoantibody generation. This study aimed to determine whether neutrophil apoptosis is altered in patients with juvenile-onset SLE as compared with controls. Methods Apoptosis was measured in neutrophils from patients with juvenile-onset SLE (n = 12), adult-onset SLE (n = 6), and pediatric patients with inflammatory (n = 12) and noninflammatory (n = 12) conditions. Annexin V staining and flow cytometry were used to determine neutrophil apoptosis. Proapoptotic and antiapoptotic proteins were measured in sera and in neutrophil cell lysates. Results Neutrophil apoptosis was significantly increased in patients with juvenile-onset SLE as compared with the noninflammatory controls at time 0. Incubation of neutrophils with sera from patients with juvenile-onset SLE further increased neutrophil apoptosis as compared with incubation with sera from pediatric controls. Concentrations of TRAIL and FasL were significantly increased in sera from patients with juvenile-onset SLE, whereas interleukin-6, tumor necrosis factor ,, and granulocyte,macrophage colony-stimulating factor (GM-CSF) were significantly decreased. Addition of GM-CSF to sera from patients with juvenile-onset SLE significantly decreased neutrophil apoptosis as compared with juvenile-onset SLE sera alone. The expression of proapoptotic proteins (caspase 3, Fas, and FADD) was elevated in juvenile-onset SLE neutrophils, whereas the expression of antiapoptotic proteins (cellular inhibitor of apoptosis 1 and 2 and X-linked inhibitor of apoptosis) was decreased. Neutrophil apoptosis correlated with biomarkers of disease activity (erythrocyte sedimentation rate and double-stranded DNA concentration) and the British Isles Lupus Assessment Group disease activity score. Conclusion Our data demonstrate an imbalance in proapoptotic and antiapoptotic factors in both neutrophils and sera from patients with juvenile-onset SLE. This imbalance results in increased neutrophil apoptosis in these patients. Correlations with markers of disease activity indicate that altered neutrophil apoptosis in juvenile-onset SLE patients may play a pathogenic role in this condition. [source] Keeping your vascular integrity: What can we learn from fish?BIOESSAYS, Issue 5 2008Aernout Luttun The cardiovascular system has the life-providing task of delivering oxygen and any flaw in this system can be life-threatening. This has encouraged extensive studies to elucidate the mechanisms behind cardiovascular development/homeostasis. The zebrafish has emerged as a formidable tool to speed up this quest, as illustrated in a recent issue of Nature Genetics.1 Baculovirus IAP repeat c2 (BIRC2), also termed cellular inhibitor of apoptosis (cIAP)-1, was found to specifically prevent endothelial cells (ECs, lining the inside of vessels) from going into suicide mode (,apoptosis') and so preserve vessel integrity. Here, we summarize the factors determining vascular integrity and elaborate on the suitability of the zebrafish to study this phenomenon. BioEssays 30:418,422, 2008. © 2008 Wiley Periodicals, Inc. [source] Inhibition of caspase-dependent spontaneous apoptosis via a cAMP-protein kinase A dependent pathway in neutrophils from sickle cell disease patientsBRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2007Nicola Conran Summary Sickle cell disease (SCD) is a chronic inflammatory condition characterized by high leucocyte counts, altered cytokine levels and endothelial cell injury. As the removal of inflammatory cells by apoptosis is fundamental for the resolution of inflammation, we aimed to determine whether the leucocyte apoptotic process is altered in SCD. Neutrophils from SCD individuals showed an inhibition of spontaneous apoptosis when cultured in vitro, in the presence of autologous serum for 20 h. Intracellular cyclic adenosine monophosphate (cAMP) levels were approximately twofold increased in SCD neutrophils; possible cAMP-upregulating factors present in SCD serum include interleukin-8, granulocyte-macrophage colony-stimulating factor and prostaglandin. Accordingly, co-incubation of SCD neutrophils with KT5720, a cAMP-dependent protein kinase (PKA) inhibitor, abrogated increased SCD neutrophil survival. Caspase-3 activity was also significantly diminished in SCD neutrophils cultured for 16 h and this activity was restored when cells were co-incubated with KT5720. BIRC2 (encoding cellular inhibitor of apoptosis protein 1, cIAP1), MCL1 and BAX expression were unaltered in SCD neutrophils; however, BIRC3 (encoding the caspase inhibitor, cIAP2), was expressed at significantly higher levels. Thus, we report an inhibition of spontaneous SCD neutrophil apoptosis that appears to be mediated by upregulated cAMP-PKA signalling and decreased caspase activity. Increased neutrophil survival may have significant consequences in SCD; contributing to leucocytosis, tissue damage and exacerbation of the chronic inflammatory state. [source] | ||||||||||