The Experts below are selected from a list of 210867 Experts worldwide ranked by ideXlab platform
Jurg Tschopp - One of the best experts on this subject based on the ideXlab platform.
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inflammatory caspases linking an intracellular innate immune system to autoinflammatory diseases
Cell, 2004Co-Authors: Fabio Martinon, Jurg TschoppAbstract:Abstract Caspases not only play an essential role during apoptotic cell death, but a subfamily of them—the inflammatory caspases—are associated with immune responses to microbial pathogens. Activation of inflammatory caspases, such as caspase-1 and Caspase-5, occurs upon assembly of an intracellular complex, designated the inflammasome. This results in the cleavage and activation of the proinflammatory cytokines IL-1β and IL-18. Mutations in one of the scaffold proteins of the inflammasome, NALP3/Cryopyrin, are associated with autoinflammatory disorders underscoring the importance of regulating inflammatory caspase activation.
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inflammatory caspases linking an intracellular innate immune system to autoinflammatory diseases
Cell, 2004Co-Authors: Fabio Martinon, Jurg TschoppAbstract:Caspases not only play an essential role during apoptotic cell death, but a subfamily of them-the inflammatory caspases-are associated with immune responses to microbial pathogens. Activation of inflammatory caspases, such as caspase-1 and Caspase-5, occurs upon assembly of an intracellular complex, designated the inflammasome. This results in the cleavage and activation of the proinflammatory cytokines IL-1beta and IL-18. Mutations in one of the scaffold proteins of the inflammasome, NALP3/Cryopyrin, are associated with autoinflammatory disorders underscoring the importance of regulating inflammatory caspase activation.
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the inflammasome a molecular platform triggering activation of inflammatory caspases and processing of proil beta
Molecular Cell, 2002Co-Authors: Fabio Martinon, Kimberly Burns, Jurg TschoppAbstract:Abstract Generation of Interleukin (IL)-1β via cleavage of its proform requires the activity of caspase-1 (and caspase-11 in mice), but the mechanism involved in the activation of the proinflammatory caspases remains elusive. Here we report the identification of a caspase-activating complex that we call the inflammasome. The inflammasome comprises caspase-1, Caspase-5, Pycard/Asc, and NALP1, a Pyrin domain-containing protein sharing structural homology with NODs. Using a cell-free system, we show that proinflammatory caspase activation and proIL-1β processing is lost upon prior immunodepletion of Pycard. Moreover, expression of a dominant-negative form of Pycard in differentiated THP-1 cells blocks proIL-1β maturation and activation of inflammatory caspases induced by LPS in vivo. Thus, the inflammasome constitutes an important arm of the innate immunity.
Douglas R Green - One of the best experts on this subject based on the ideXlab platform.
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caspase 3 is the primary activator of apoptotic dna fragmentation via dna fragmentation factor 45 inhibitor of caspase activated dnase inactivation
Journal of Biological Chemistry, 1999Co-Authors: Beni B Wolf, Fernando Echeverri, Martin Schuler, Douglas R GreenAbstract:Caspase-3 initiates apoptotic DNA fragmentation by proteolytically inactivating DFF45 (DNA fragmentation factor-45)/ICAD (inhibitor of caspase-activated DNase), which releases active DFF40/CAD (caspase-activated DNase), the inhibitor's associated endonuclease. Here, we examined whether other apoptotic proteinases initiated DNA fragmentation via DFF45/ICAD inactivation. In a cell-free assay, caspases-3, -6, -7, -8, and granzyme B initiated benzoyloxycarbonyl-Asp-Glu-Val-Asp (DEVD) cleaving caspase activity, DFF45/ICAD inactivation, and DNA fragmentation, but calpain and cathepsin D failed to initiate these events. Strikingly, only the DEVD cleaving caspases, caspase-3 and caspase-7, inactivated DFF45/ICAD and promoted DNA fragmentation in an in vitro DFF40/CAD assay, suggesting that granzyme B, caspase-6, and caspase-8 promote DFF45/ICAD inactivation and DNA fragmentation indirectly by activating caspase-3 and/or caspase-7. In vitro, however, caspase-3 inactivated DFF45/ICAD and promoted DNA fragmentation more effectively than caspase-7 and endogenous levels of caspase-7 failed to inactivate DFF45/ICAD in caspase-3 null MCF7 cells and extracts. Together, these data suggest that caspase-3 is the primary inactivator of DFF45/ICAD and therefore the primary activator of apoptotic DNA fragmentation.
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caspase 3 is the primary activator of apoptotic dna fragmentation via dna fragmentation factor 45 inhibitor of caspase activated dnase inactivation
Journal of Biological Chemistry, 1999Co-Authors: Beni B Wolf, Fernando Echeverri, Martin Schuler, Douglas R GreenAbstract:Next Section Abstract Caspase-3 initiates apoptotic DNA fragmentation by proteolytically inactivating DFF45 (DNA fragmentation factor-45)/ICAD (inhibitor of caspase-activated DNase), which releases active DFF40/CAD (caspase-activated DNase), the inhibitor's associated endonuclease. Here, we examined whether other apoptotic proteinases initiated DNA fragmentation via DFF45/ICAD inactivation. In a cell-free assay, caspases-3, -6, -7, -8, and granzyme B initiated benzoyloxycarbonyl-Asp-Glu-Val-Asp (DEVD) cleaving caspase activity, DFF45/ICAD inactivation, and DNA fragmentation, but calpain and cathepsin D failed to initiate these events. Strikingly, only the DEVD cleaving caspases, caspase-3 and caspase-7, inactivated DFF45/ICAD and promoted DNA fragmentation in an in vitro DFF40/CAD assay, suggesting that granzyme B, caspase-6, and caspase-8 promote DFF45/ICAD inactivation and DNA fragmentation indirectly by activating caspase-3 and/or caspase-7. In vitro, however, caspase-3 inactivated DFF45/ICAD and promoted DNA fragmentation more effectively than caspase-7 and endogenous levels of caspase-7 failed to inactivate DFF45/ICAD in caspase-3 null MCF7 cells and extracts. Together, these data suggest that caspase-3 is the primary inactivator of DFF45/ICAD and therefore the primary activator of apoptotic DNA fragmentation.
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calpain functions in a caspase independent manner to promote apoptosis like events during platelet activation
Blood, 1999Co-Authors: Beni B Wolf, Joshua C Goldstein, Henning R Stennicke, Helen M Beere, Gustavo P Amarantemendes, Guy S Salvesen, Douglas R GreenAbstract:Apoptosis and platelet activation share common morphological and biochemical features. Because caspases are essential mediators of apoptosis, we examined whether platelets contain these proteinases and use them during platelet activation. Human platelets contained caspase-9, caspase-3, and the caspase activators APAF-1 and cytochrome c as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Upon treatment with cytochrome c and dATP, platelet cytoplasmic extracts recapitulated apoptotic events, including sequential activation of procaspase-9 and procaspase-3 and subsequent proteolysis of caspase substrates. Calcium ionophore-stimulated platelets also recapitulated apoptotic events, including cell shrinkage, plasma membrane microvesiculation, phosphatidyl serine externalization, and proteolysis of procaspase-9, procaspase-3, gelsolin, and protein kinase C-δ. Strikingly, however, these events occurred without caspase activation or release of mitochondrial cytochrome c, suggesting a role for a noncaspase proteinase. Supporting this, inhibition of the calcium-dependent proteinase, calpain, prevented caspase proteolysis, ‘apoptotic’ substrate cleavage, and platelet microvesiculation. In vitro, purified calpain cleaved recombinant procaspase-9 and procaspase-3 without activating either caspase, confirming the inhibitor studies. These data implicate calpain as a potential regulator of caspases and suggest that calpain, not caspases, promotes apoptosis-like events during platelet activation.
Gerald M. Cohen - One of the best experts on this subject based on the ideXlab platform.
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Ordering of caspases in cells undergoing apoptosis by the intrinsic pathway.
Cell death and differentiation, 2009Co-Authors: Satoshi Inoue, Gareth J. Browne, Gennaro Melino, Gerald M. CohenAbstract:Caspases are a family of aspartate-specific cysteine proteases responsible for the biochemical and morphological changes that occur during the execution phase of apoptosis. The hierarchical ordering of caspases has been clearly established using dATP-activated cell lysates to model the intrinsic pathway induced by initial mitochondrial perturbation. In this model, caspase-9, the apical caspase, directly processes and activates the effector caspases, caspase-3 and -7, and then active caspase-3 but not caspase-7, processes caspase-2 and -6, and subsequently the activated caspase-6 processes caspase-8 and -10. To address the possibility that this model in vitro system might not reflect the precise ordering of caspases in intact cells, we have examined this possibility in cells induced to undergo apoptosis by activation of the intrinsic pathway. We have used caspase deficient cells, small interference RNA for caspase-6 and -7, and a specific caspase-3 inhibitor. In contrast to the earlier in vitro studies, we now show that in intact cells caspase-7 can also directly process and activate caspase-2 and -6. The processing of caspase-2 and -6 occurs within the cytoplasm and active caspase-6 is then responsible for both the processing of caspase-8 and the cleavage of caspase-6 substrates, including lamin A/C.
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xiap inhibition of caspase 3 preserves its association with the apaf 1 apoptosome and prevents cd95 and bax induced apoptosis
Cell Death & Differentiation, 2002Co-Authors: Shawn B. Bratton, Michael Butterworth, Jennifer M Lewis, Colin S Duckett, Gerald M. CohenAbstract:Ligation of death receptors or formation of the Apaf-1 apoptosome results in the activation of caspases and execution of apoptosis. We recently demonstrated that X-linked inhibitor-of-apoptosis protein (XIAP) associates with the apoptosome in vitro. By utilizing XIAP mutants, we now report that XIAP binds to the ‘native’ apoptosome complex via a specific interaction with the small p12 subunit of processed caspase-9. Indeed, we provide the first direct evidence that XIAP can simultaneously bind active caspases-9 and -3 within the same complex and that inhibition of caspase-3 by the Linker-BIR2 domain prevents disruption of BIR3-caspase-9 interactions. Recent studies suggest that inhibition of caspase-3 is dispensable for its anti-apoptotic effects. However, we clearly demonstrate that inhibition of caspase-3 is required to inhibit CD95 (Fas/Apo-1)-mediated apoptosis, whereas inhibition of either caspase-9 or caspase-3 prevents Bax-induced cell death. Finally, we illustrate for the first time that XIAP mutants, which are incapable of binding to caspases-9 and -3 are completely devoid of anti-apoptotic activity. Thus, XIAP's capacity to maintain inhibition of caspase-9 within the Apaf-1 apoptosome is influenced by its ability to simultaneously inhibit active caspase-3, and depending upon the apoptotic stimulus, inhibition of caspase-9 or 3 is essential for XIAP's anti-apoptotic activity.
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caspase activation involves the formation of the aposome a large 700 kda caspase activating complex
Journal of Biological Chemistry, 1999Co-Authors: Kelvin Cain, David Brown, Claudia Langlais, Gerald M. CohenAbstract:In mammals, apoptotic protease-activating factor 1 (Apaf-1), cytochrome c, and dATP activate caspase-9, which initiates the postmitochondrial-mediated caspase cascade by proteolytic cleavage/activation of effector caspases to form active approximately 60-kDa heterotetramers. We now demonstrate that activation of caspases either in apoptotic cells or following dATP activation of cell lysates results in the formation of two large but different sized protein complexes, the "aposome" and the "microaposome". Surprisingly, most of the DEVDase activity in the lysate was present in the aposome and microaposome complexes with only small amounts of active caspase-3 present as its free approximately 60-kDa heterotetramer. The larger aposome complex (M(r) = approximately 700,000) contained Apaf-1 and processed caspase-9, -3, and -7. The smaller microaposome complex (M(r) = approximately 200,000-300,000) contained active caspase-3 and -7 but little if any Apaf-1 or active caspase-9. Lysates isolated from control THP.1 cells, prior to caspase activation, showed striking differences in the distribution of key apoptotic proteins. Apaf-1 and procaspase-7 may be functionally complexed as they eluted as an approximately 200-300-kDa complex, which did not have caspase cleavage (DEVDase) activity. Procaspase-3 and -9 were present as separate and smaller 60-90-kDa (dimer) complexes. During caspase activation, Apaf-1, caspase-9, and the effector caspases redistributed and formed the aposome. This resulted in the processing of the effector caspases, which were then released, possibly bound to other proteins, to form the microaposome complex.
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Different Subcellular Distribution of Caspase-3 and Caspase-7 following Fas-induced Apoptosis in Mouse Liver
The Journal of biological chemistry, 1998Co-Authors: Julia M. Chandler, Gerald M. Cohen, Marion MacfarlaneAbstract:Caspases plays a key role in the execution phase of apoptosis. "Initiator" caspases, such as caspase-8, activate "effector" caspases, such as caspase-3 and -7, which subsequently cleave cellular substrates thereby precipitating the dramatic morphological changes of apoptosis. Following treatment of mice with an agonistic anti-Fas antibody to induce massive hepatocyte apoptosis, we now demonstrate a distinct subcellular localization of the effector caspases-3 and -7. Active caspase-3 is confined primarily to the cytosol, whereas active caspase-7 is associated almost exclusively with the mitochondrial and microsomal fractions. These data suggest that caspases-3 and -7 exert their primary functions in different cellular compartments and offer a possible explanation of the presence of caspase homologs with overlapping substrate specificities. Translocation and activation of caspase-7 to the endoplasmic reticulum correlates with the proteolytic cleavage of the endoplasmic reticular-specific substrate, sterol regulatory element-binding protein 1. Liver damage, induction of apoptosis, activation and translocation of caspase-7, and proteolysis of sterol regulatory element-binding protein 1 are all blocked by the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD. fmk). Our data demonstrate for the first time the differential subcellular compartmentalization of specific effector caspases following the induction of apoptosis in vivo.
Beni B Wolf - One of the best experts on this subject based on the ideXlab platform.
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caspase 3 is the primary activator of apoptotic dna fragmentation via dna fragmentation factor 45 inhibitor of caspase activated dnase inactivation
Journal of Biological Chemistry, 1999Co-Authors: Beni B Wolf, Fernando Echeverri, Martin Schuler, Douglas R GreenAbstract:Next Section Abstract Caspase-3 initiates apoptotic DNA fragmentation by proteolytically inactivating DFF45 (DNA fragmentation factor-45)/ICAD (inhibitor of caspase-activated DNase), which releases active DFF40/CAD (caspase-activated DNase), the inhibitor's associated endonuclease. Here, we examined whether other apoptotic proteinases initiated DNA fragmentation via DFF45/ICAD inactivation. In a cell-free assay, caspases-3, -6, -7, -8, and granzyme B initiated benzoyloxycarbonyl-Asp-Glu-Val-Asp (DEVD) cleaving caspase activity, DFF45/ICAD inactivation, and DNA fragmentation, but calpain and cathepsin D failed to initiate these events. Strikingly, only the DEVD cleaving caspases, caspase-3 and caspase-7, inactivated DFF45/ICAD and promoted DNA fragmentation in an in vitro DFF40/CAD assay, suggesting that granzyme B, caspase-6, and caspase-8 promote DFF45/ICAD inactivation and DNA fragmentation indirectly by activating caspase-3 and/or caspase-7. In vitro, however, caspase-3 inactivated DFF45/ICAD and promoted DNA fragmentation more effectively than caspase-7 and endogenous levels of caspase-7 failed to inactivate DFF45/ICAD in caspase-3 null MCF7 cells and extracts. Together, these data suggest that caspase-3 is the primary inactivator of DFF45/ICAD and therefore the primary activator of apoptotic DNA fragmentation.
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caspase 3 is the primary activator of apoptotic dna fragmentation via dna fragmentation factor 45 inhibitor of caspase activated dnase inactivation
Journal of Biological Chemistry, 1999Co-Authors: Beni B Wolf, Fernando Echeverri, Martin Schuler, Douglas R GreenAbstract:Caspase-3 initiates apoptotic DNA fragmentation by proteolytically inactivating DFF45 (DNA fragmentation factor-45)/ICAD (inhibitor of caspase-activated DNase), which releases active DFF40/CAD (caspase-activated DNase), the inhibitor's associated endonuclease. Here, we examined whether other apoptotic proteinases initiated DNA fragmentation via DFF45/ICAD inactivation. In a cell-free assay, caspases-3, -6, -7, -8, and granzyme B initiated benzoyloxycarbonyl-Asp-Glu-Val-Asp (DEVD) cleaving caspase activity, DFF45/ICAD inactivation, and DNA fragmentation, but calpain and cathepsin D failed to initiate these events. Strikingly, only the DEVD cleaving caspases, caspase-3 and caspase-7, inactivated DFF45/ICAD and promoted DNA fragmentation in an in vitro DFF40/CAD assay, suggesting that granzyme B, caspase-6, and caspase-8 promote DFF45/ICAD inactivation and DNA fragmentation indirectly by activating caspase-3 and/or caspase-7. In vitro, however, caspase-3 inactivated DFF45/ICAD and promoted DNA fragmentation more effectively than caspase-7 and endogenous levels of caspase-7 failed to inactivate DFF45/ICAD in caspase-3 null MCF7 cells and extracts. Together, these data suggest that caspase-3 is the primary inactivator of DFF45/ICAD and therefore the primary activator of apoptotic DNA fragmentation.
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calpain functions in a caspase independent manner to promote apoptosis like events during platelet activation
Blood, 1999Co-Authors: Beni B Wolf, Joshua C Goldstein, Henning R Stennicke, Helen M Beere, Gustavo P Amarantemendes, Guy S Salvesen, Douglas R GreenAbstract:Apoptosis and platelet activation share common morphological and biochemical features. Because caspases are essential mediators of apoptosis, we examined whether platelets contain these proteinases and use them during platelet activation. Human platelets contained caspase-9, caspase-3, and the caspase activators APAF-1 and cytochrome c as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Upon treatment with cytochrome c and dATP, platelet cytoplasmic extracts recapitulated apoptotic events, including sequential activation of procaspase-9 and procaspase-3 and subsequent proteolysis of caspase substrates. Calcium ionophore-stimulated platelets also recapitulated apoptotic events, including cell shrinkage, plasma membrane microvesiculation, phosphatidyl serine externalization, and proteolysis of procaspase-9, procaspase-3, gelsolin, and protein kinase C-δ. Strikingly, however, these events occurred without caspase activation or release of mitochondrial cytochrome c, suggesting a role for a noncaspase proteinase. Supporting this, inhibition of the calcium-dependent proteinase, calpain, prevented caspase proteolysis, ‘apoptotic’ substrate cleavage, and platelet microvesiculation. In vitro, purified calpain cleaved recombinant procaspase-9 and procaspase-3 without activating either caspase, confirming the inhibitor studies. These data implicate calpain as a potential regulator of caspases and suggest that calpain, not caspases, promotes apoptosis-like events during platelet activation.
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ordering the cytochrome c initiated caspase cascade hierarchical activation of caspases 2 3 6 7 8 and 10 in a caspase 9 dependent manner
Journal of Cell Biology, 1999Co-Authors: Elizabeth A Slee, Mary T Harte, Ruth M Kluck, Beni B Wolf, Carlos A Casiano, Donald D Newmeyer, John C Reed, Donald W Nicholson, Honggang Wang, Emad S AlnemriAbstract:Exit of cytochrome c from mitochondria into the cytosol has been implicated as an important step in apoptosis. In the cytosol, cytochrome c binds to the CED-4 homologue, Apaf-1, thereby triggering Apaf-1–mediated activation of caspase-9. Caspase-9 is thought to propagate the death signal by triggering other caspase activation events, the details of which remain obscure. Here, we report that six additional caspases (caspases-2, -3, -6, -7, -8, and -10) are processed in cell-free extracts in response to cytochrome c, and that three others (caspases-1, -4, and -5) failed to be activated under the same conditions. In vitro association assays confirmed that caspase-9 selectively bound to Apaf-1, whereas caspases-1, -2, -3, -6, -7, -8, and -10 did not. Depletion of caspase-9 from cell extracts abrogated cytochrome c–inducible activation of caspases-2, -3, -6, -7, -8, and -10, suggesting that caspase-9 is required for all of these downstream caspase activation events. Immunodepletion of caspases-3, -6, and -7 from cell extracts enabled us to order the sequence of caspase activation events downstream of caspase-9 and reveal the presence of a branched caspase cascade. Caspase-3 is required for the activation of four other caspases (-2, -6, -8, and -10) in this pathway and also participates in a feedback amplification loop involving caspase-9.
Stephanie Zwicker - One of the best experts on this subject based on the ideXlab platform.
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th17 micro milieu regulates nlrp1 dependent caspase 5 activity in skin autoinflammation
PLOS ONE, 2017Co-Authors: Aleksandra Batyckabaran, Eva Hattinger, Stephanie Zwicker, D Bureik, Andreas Schmidt, Peterarne Gerber, Simon Rothenfusser, Michel GillietAbstract:IL-1β is a potent player in cutaneous inflammation and central for the development of a Th17 micro-milieu in autoinflammatory diseases including psoriasis. Its production is controlled at the transcriptional level and by subsequent posttranslational processing via inflammatory caspases. In this study, we detected inflammatory Caspase-5 active in epidermal keratinocytes and in psoriatic skin lesions. Further, interferon-γ and interleukin-17A synergistically induced Caspase-5 expression in cultured keratinocytes, which was dependent on the antimicrobial peptide psoriasin (S100A7). However, diseases-relevant triggers for Caspase-5 activity and IL-1β production remain unknown. Recently, extranuclear DNA has been identified as danger-signals abundant in the psoriatic epidermis. Here, we could demonstrate that cytosolic double-stranded (ds) DNA transfected into keratinocytes triggered the activation of Caspase-5 and the release of IL-1β. Further, interleukin-17A promoted Caspase-5 function via facilitation of the NLRP1-inflammasome. Anti-inflammatory vitamin D interfered with the IL-1β release and suppressed Caspase-5 in keratinocytes and in psoriatic skin lesions. Our data link the disease-intrinsic danger signals psoriasin (S100A7) and dsDNA for NLPR1-dependent Caspase-5 activity in psoriasis providing potential therapeutic targets in Th17-mediated skin autoinflammation.