The Experts below are selected from a list of 208614 Experts worldwide ranked by ideXlab platform
Douglas R Green - One of the best experts on this subject based on the ideXlab platform.
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Caspase 8 regulating life and death
Immunological Reviews, 2017Co-Authors: Bart Tummers, Douglas R GreenAbstract:Roles for cell death in development, homeostasis, and the control of infections and cancer have long been recognized. Although excessive cell damage results in passive necrosis, cells can be triggered to engage molecular programs that result in cell death. Such triggers include cellular stress, oncogenic signals that engage tumor suppressor mechanisms, pathogen insults, and immune mechanisms. The best-known forms of programmed cell death are apoptosis and a recently recognized regulated necrosis termed necroptosis. Of the two best understood pathways of apoptosis, the extrinsic and intrinsic (mitochondrial) pathways, the former is induced by the ligation of death receptors, a subset of the TNF receptor (TNFR) superfamily. Ligation of these death receptors can also induce necroptosis. The extrinsic apoptosis and necroptosis pathways regulate each other and their balance determines whether cells live. Integral in the regulation and initiation of death receptor-mediated activation of programmed cell death is the aspartate-specific cysteine protease (Caspase)-8. This review describes the role of Caspase-8 in the initiation of extrinsic apoptosis execution and the mechanism by which Caspase-8 inhibits necroptosis. The importance of Caspase-8 in the development and homeostasis and the way that dysfunctional Caspase-8 may contribute to the development of malignancies in mice and humans are also explored.
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fadd and Caspase 8 mediate priming and activation of the canonical and noncanonical nlrp3 inflammasomes
Journal of Immunology, 2014Co-Authors: Prajwal Gurung, Ricardo Weinlich, Christopher P. Dillon, Paras K Anand, R Subbarao K Malireddi, Lieselotte Vande Walle, Nina Van Opdenbosch, Douglas R GreenAbstract:The Nlrp3 inflammasome is critical for host immunity, but the mechanisms controlling its activation are enigmatic. In this study, we show that loss of FADD or Caspase-8 in a RIP3-deficient background, but not RIP3 deficiency alone, hampered transcriptional priming and posttranslational activation of the canonical and noncanonical Nlrp3 inflammasome. Deletion of Caspase-8 in the presence or absence of RIP3 inhibited Caspase-1 and Caspase-11 activation by Nlrp3 stimuli but not the Nlrc4 inflammasome. In addition, FADD deletion prevented Caspase-8 maturation, positioning FADD upstream of Caspase-8. Consequently, FADD- and Caspase-8-deficient mice had impaired IL-1β production when challenged with LPS or infected with the enteropathogen Citrobacter rodentium. Thus, our results reveal FADD and Caspase-8 as apical mediators of canonical and noncanonical Nlrp3 inflammasome priming and activation.
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Survival function of the FADD-Caspase-8-cFLIP(L) complex.
Cell reports, 2012Co-Authors: Christopher P. Dillon, Ricardo Weinlich, Andrew Oberst, Laura J. Janke, Tae Bong Kang, Tehila Ben-moshe, Tak W. Mak, David Wallach, Douglas R GreenAbstract:Caspase-8, the initiator Caspase of the death receptor pathway of apoptosis, its adapter molecule, FADD, required for Caspase-8 activation, and cFLIPL, a Caspase-8-like protein that lacks a catalytic site and blocks Caspase-8-mediated apoptosis, are each essential for embryonic development. Animals deficient in any of these genes present with E10.5 embryonic lethality. Recent studies have shown that development in Caspase-8-deficient mice is rescued by ablation of RIPK3, a kinase that promotes a form of programmed, necrotic cell death. Here, we show that FADD, RIPK3 double-knockout mice develop normally but that the lethal effects of cFLIP deletion are not rescued by RIPK3 deficiency. Remarkably, in mice lacking FADD, cFLIP, and RIPK3, embryonic development is normal. This can be explained by the convergence of two cell processes: the enzymatic activity of the FADD-Caspase-8-cFLIPL complex blocks RIPK3-dependent signaling (including necrosis), whereas cFLIPL blocks RIPK3-independent apoptosis promoted by the FADD-Caspase-8 complex.
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Caspase 8 inhibits programmed necrosis by processing CYLD
Nature Cell Biology, 2011Co-Authors: Marie Anne O’donnell, Andrew Oberst, Douglas R Green, Eva Perez-jimenez, Aylwin Ng, Ramin Massoumi, Ramnik J. Xavier, Adrian T. TingAbstract:Caspase 8 initiates apoptosis downstream of TNF death receptors by undergoing autocleavage and processing the executioner Caspase 3 (ref. 1). However, the dominant function of Caspase 8 is to transmit a pro-survival signal that suppresses programmed necrosis (or necroptosis) mediated by RIPK1 and RIPK3 (refs 2-6) during embryogenesis and haematopoiesis(7-9). Suppression of necrotic cell death by Caspase 8 requires its catalytic activity but not the autocleavage essential for apoptosis(10); however, the key substrate processed by Caspase 8 to block necrosis has been elusive. A key substrate must meet three criteria: it must be essential for programmed necrosis; it must be cleaved by Caspase 8 in situations where Caspase 8 is blocking necrosis; and mutation of the Caspase 8 processing site on the substrate should convert a pro-survival response to necrotic death without the need for Caspase 8 inhibition. We now identify CYLD as a substrate for Caspase 8 that satisfies these criteria. Following TNF stimulation, Caspase 8 cleaves CYLD to generate a survival signal. In contrast, loss of Caspase 8 prevented CYLD degradation, resulting in necrotic death. A CYLD substitution mutation at Asp 215 that cannot be cleaved by Caspase 8 switches cell survival to necrotic cell death in response to TNF.
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catalytic activity of the Caspase 8 flip l complex inhibits ripk3 dependent necrosis
Nature, 2011Co-Authors: Andrew Oberst, Ricardo Weinlich, Christopher P. Dillon, Guy S Salvesen, Laura L Mccormick, Patrick Fitzgerald, Razq Hakem, Douglas R GreenAbstract:Caspase-8 mediates apoptosis induced by 'death receptors' on the cell's surface. At the same time, it is able to prevent receptor interacting protein kinase (RIPK)-dependent necrosis. Without Caspase-8, mice die during embryonic development, but why this happens is not clear. Two groups show that this lethality is not caused by the absence of apoptosis, but by the RIPK3-dependent necrosis that is unleashed without Caspase-8. Mice lacking both Caspase-8 and RIP3 develop into viable, immunocompetent adults, but have a progressive lymphoaccumulative disease similar to that in mice that lack the CD95 death receptor. Oberst et al. also show that Caspase-8 forms a proteolytically active complex with FLICE-like inhibitory protein long (FLIPL), and that this complex is required for protection against RIP3-dependent necrosis. Caspase-8 mediates apoptosis induced by death receptors. At the same time, this protease is able to prevent RIP-dependent necrosis. Without Caspase-8 mice die during their embryonic development. Two papers now show that lethality is not caused by the absence of apoptosis, but by RIP3-dependent necrosis that is unleashed without Caspase-8. Mice that lack both Caspase-8 and RIP3 develop into viable, immunocompetent, fertile adult mice, but suffer from a progressive lymphoaccumulative disease similar to mice that lack the death receptor CD95. This paper further shows that Caspase-8 forms a proteolytically active complex with FLIPL, and that this complex is required for protection against RIP3-dependent necrosis. Caspase-8 has two opposing biological functions—it promotes cell death by triggering the extrinsic pathway of apoptosis, but also has a survival activity, as it is required for embryonic development1, T-lymphocyte activation2, and resistance to necrosis induced by tumour necrosis factor-α (TNF-α) and related family ligands3,4. Here we show that development of Caspase-8-deficient mice is completely rescued by ablation of receptor interacting protein kinase-3 (RIPK3). Adult animals lacking both Caspase-8 and RIPK3 display a progressive lymphoaccumulative disease resembling that seen with defects in CD95 or CD95-ligand (also known as FAS and FASLG, respectively), and resist the lethal effects of CD95 ligation in vivo. We have found that Caspase-8 prevents RIPK3-dependent necrosis without inducing apoptosis by functioning in a proteolytically active complex with FLICE-like inhibitory protein long (FLIPL, also known as CFLAR), and this complex is required for the protective function.
Dwayne G. Stupack - One of the best experts on this subject based on the ideXlab platform.
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Caspase-8 isoform 6 promotes death effector filament formation independent of microtubules
Apoptosis, 2012Co-Authors: Robert T. Yuan, Ainhoa Mielgo, Shanique Young, Jesse Liang, Michael C. Schmid, Dwayne G. StupackAbstract:Caspase-8 can trigger cell death following prodomain-mediated recruitment to the ‘death-inducing signaling complex.’ The prodomain consists of two death effector domain (DED) motifs that undergo homotypic interactions within the cell. Aside from mediating recruitment of proCaspase-8, the prodomains have also been implicated in regulating cell survival, proliferation, death, senescence, differentiation, and substrate attachment. Here, we perform the initial characterization of a novel isoform of Caspase-8, designated Caspase-8 isoform 6 (Casp-8.6), which encodes both prodomain DEDs followed by a unique C-terminal tail. Casp-8.6 is detected in cells of the hematopoietic compartment as well as several other tissues. When Casp-8.6 expression is reconstituted in Caspase-8-deficient cells, Casp-8.6 does not significantly impact cellular proliferation, contrasting with our previous results using a domain-defined ‘DED-only’ construct that lacks the C-terminal tail. Like the DED-only construct, Casp-8.6 also robustly forms ‘death effector’ filaments, but in contrast to the DED construct, it does not exhibit a dependence upon intact microtubules to scaffold filament formation. Both types of death effector filaments promote apoptosis when expressed in the presence of full length Caspase-8 (isoform 1). Together, the results implicate Casp-8.6 as a new physiological modulator of apoptosis.
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the death effector domains of Caspase 8 induce terminal differentiation
PLOS ONE, 2009Co-Authors: Ainhoa Mielgo, Vicente A Torres, Simone Barbero, Pedro Lee, Colin Jamora, M Schmid, Ryon P Graf, Samantha G Zeitlin, David J Shields, Dwayne G. StupackAbstract:The differentiation and senescence programs of metazoans play key roles in regulating normal development and preventing aberrant cell proliferation, such as cancer. These programs are intimately associated with both the mitotic and apoptotic pathways. Caspase-8 is an apical apoptotic initiator that has recently been appreciated to coordinate non-apoptotic roles in the cell. Most of these functions are attributed to the catalytic domain, however, the amino-terminal death effector domains (DED)s, which belong to the death domain superfamily of proteins, can also play key roles during development. Here we describe a novel role for Caspase-8 DEDs in regulating cell differentiation and senescence. Caspase-8 DEDs accumulate during terminal differentiation and senescence of epithelial, endothelial and myeloid cells; genetic deletion or shRNA suppression of Caspase-8 disrupts cell differentiation, while re-expression of DEDs rescues this phenotype. Among Caspase-8 deficient neuroblastoma cells, DED expression attenuated tumor growth in vivo and proliferation in vitro via disruption of mitosis and cytokinesis, resulting in upregulation of p53 and induction of differentiation markers. These events occur independent of Caspase-8 catalytic activity, but require a critical lysine (K156) in a microtubule-binding motif in the second DED domain. The results demonstrate a new function for the DEDs of Caspase-8, and describe an unexpected mechanism that contributes to cell differentiation and senescence.
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paclitaxel promotes a Caspase 8 mediated apoptosis through death effector domain association with microtubules
Oncogene, 2009Co-Authors: Ainhoa Mielgo, Vicente A Torres, Kiran Clair, Simone Barbero, Dwayne G. StupackAbstract:Microtubule-perturbing drugs have become front-line chemotherapeutics, inducing cell-cycle crisis as a major mechanism of action. However, these agents show pleiotropic effects on cells and can induce apoptosis through other means. Paclitaxel, a microtubule-stabilizing agent, induces a Caspase-dependent apoptosis, although the precise mechanism(s) remain unclear. Here, we used genetic approaches to evaluate the role of Caspase 8 in paclitaxel-mediated apoptosis. We observed that Caspase 8-expressing cells are more sensitive to paclitaxel than Caspase 8-deficient cells. Mechanistically, Caspase 8 was found associated with microtubules, and this interaction increased after paclitaxel treatment. The prodomains death effector domains (DEDs) of Caspase 8 were sufficient for interaction with microtubules, but the Caspase 8 holoprotein was required for apoptosis. DED-only forms of Caspase 8 were found in both primary and tumor cell lines, associating with perinuclear microtubules and the centrosome. Microtubule association, and paclitaxel sensitivity, depends on a critical lysine (K156) within a microtubule-binding motif (KLD) in DED-b of Caspase 8. The results show an unexpected pathway of apoptosis mediated by Caspase 8.
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identification of a critical tyrosine residue in Caspase 8 that promotes cell migration
Journal of Biological Chemistry, 2008Co-Authors: Simone Barbero, Venturina Stagni, Ainhoa Mielgo, Kiran Clair, Daniela Barila, Dwayne G. StupackAbstract:Caspase 8 is a critical upstream initiator of programmed cell death but, paradoxically, has also been shown to promote cell migration. Here, we show that tyrosine 380 in the linker loop of human Caspase 8 is a critical switch determining Caspase 8 function. Our studies show that, in addition to its cytosolic distribution, Caspase 8 is recruited to lamella of migrating cells. Although the catalytic domain of Caspase 8 is sufficient for recruitment and promotion of cell migration, catalytic activity per se is not required. Instead, we find that integrin-mediated adhesion promotes Caspase 8 phosphorylation on tyrosine 380. Accordingly, mutation of this site compromises localization to the periphery and the potentiation of cell migration. Mechanistically, this linker region of Caspase 8 acts as a Src homology 2 binding site. In particular, tyrosine 380 is critical for interaction with Src homology 2 domains. The results identify a novel mechanism by which Caspase 8 is recruited to the lamella of a migrating cell, promoting cell migration independent of its protease activity.
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potentiation of neuroblastoma metastasis by loss of Caspase 8
Nature, 2006Co-Authors: Dwayne G. Stupack, Tal Teitz, Matthew D Potter, David Mikolon, Peter J Houghton, Vincent J Kidd, Jill M Lahti, David A ChereshAbstract:Neuroblastoma, the most common paediatric solid tumour, arises from defective neural crest cells. Genetic alterations occur frequently in the most aggressive neuroblastomas. In particular, deletion or suppression of the proapoptotic enzyme Caspase-8 is common in malignant, disseminated disease, although the effect of this loss on disease progression is unclear. Here we show that suppression of Caspase-8 expression occurs during the establishment of neuroblastoma metastases in vivo, and that reconstitution of Caspase-8 expression in deficient neuroblastoma cells suppressed their metastases. Caspase-8 status was not a predictor of primary tumour growth; rather, Caspase-8 selectively potentiated apoptosis in neuroblastoma cells invading the collagenous stroma at the tumour margin. Apoptosis was initiated by unligated integrins by means of a process known as integrin-mediated death. Loss of Caspase-8 or integrin rendered these cells refractory to integrin-mediated death, allowed cellular survival in the stromal microenvironment, and promoted metastases. These findings define Caspase-8 as a metastasis suppressor gene that, together with integrins, regulates the survival and invasive capacity of neuroblastoma cells.
Angelika Hausser - One of the best experts on this subject based on the ideXlab platform.
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cancer cells employ nuclear Caspase 8 to overcome the p53 dependent g2 m checkpoint through cleavage of usp28
Molecular Cell, 2020Co-Authors: Ines Muller, Elwira Strozyk, Sebastian Schindler, Sebastian Raeth, Htoo Zarni Oo, Philippe Lucarelli, Thomas Sauter, Stefan Beissert, Angelika HausserAbstract:Cytosolic Caspase-8 is a mediator of death receptor signaling. While Caspase-8 expression is lost in some tumors, it is increased in others, indicating a conditional pro-survival function of Caspase-8 in cancer. Here, we show that tumor cells employ DNA-damage-induced nuclear Caspase-8 to override the p53-dependent G2/M cell-cycle checkpoint. Caspase-8 is upregulated and localized to the nucleus in multiple human cancers, correlating with treatment resistance and poor clinical outcome. Depletion of Caspase-8 causes G2/M arrest, stabilization of p53, and induction of p53-dependent intrinsic apoptosis in tumor cells. In the nucleus, Caspase-8 cleaves and inactivates the ubiquitin-specific peptidase 28 (USP28), preventing USP28 from de-ubiquitinating and stabilizing wild-type p53. This results in de facto p53 protein loss, switching cell fate from apoptosis toward mitosis. In summary, our work identifies a non-canonical role of Caspase-8 exploited by cancer cells to override the p53-dependent G2/M cell-cycle checkpoint.
Htoo Zarni Oo - One of the best experts on this subject based on the ideXlab platform.
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cancer cells employ nuclear Caspase 8 to overcome the p53 dependent g2 m checkpoint through cleavage of usp28
Molecular Cell, 2020Co-Authors: Ines Muller, Elwira Strozyk, Sebastian Schindler, Sebastian Raeth, Htoo Zarni Oo, Philippe Lucarelli, Thomas Sauter, Stefan Beissert, Angelika HausserAbstract:Cytosolic Caspase-8 is a mediator of death receptor signaling. While Caspase-8 expression is lost in some tumors, it is increased in others, indicating a conditional pro-survival function of Caspase-8 in cancer. Here, we show that tumor cells employ DNA-damage-induced nuclear Caspase-8 to override the p53-dependent G2/M cell-cycle checkpoint. Caspase-8 is upregulated and localized to the nucleus in multiple human cancers, correlating with treatment resistance and poor clinical outcome. Depletion of Caspase-8 causes G2/M arrest, stabilization of p53, and induction of p53-dependent intrinsic apoptosis in tumor cells. In the nucleus, Caspase-8 cleaves and inactivates the ubiquitin-specific peptidase 28 (USP28), preventing USP28 from de-ubiquitinating and stabilizing wild-type p53. This results in de facto p53 protein loss, switching cell fate from apoptosis toward mitosis. In summary, our work identifies a non-canonical role of Caspase-8 exploited by cancer cells to override the p53-dependent G2/M cell-cycle checkpoint.
Avi Ashkenazi - One of the best experts on this subject based on the ideXlab platform.
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traf2 sets a threshold for extrinsic apoptosis by tagging Caspase 8 with a ubiquitin shutoff timer
Molecular Cell, 2012Co-Authors: Francois Gonzalvez, David A Lawrence, Robert M. Pitti, Jennie R. Lill, Victoria Pham, Becky Yang, Sharon Yee, Scot A Marsters, Jeanphilippe Stephan, Avi AshkenaziAbstract:Apoptotic Caspase activation mechanisms are well defined, yet inactivation modes remain unclear. The death receptors (DRs), DR4, DR5, and Fas, transduce cell-extrinsic apoptotic signals by recruiting Caspase-8 into a death-inducing signaling complex (DISC). At the DISC, Cullin3-dependent polyubiquitination on the small catalytic subunit of Caspase-8 augments stimulation. Here we report that tumor necrosis factor receptor-associated factor 2 (TRAF2) interacts with Caspase-8 at the DISC, downstream of Cullin3. TRAF2 directly mediates RING-dependent, K48-linked polyubiquitination on the large catalytic domain of Caspase-8. This modification destines activated Caspase-8 molecules to rapid proteasomal degradation upon autoprocessing and cytoplasmic translocation. TRAF2 depletion lowers the signal threshold for DR-mediated apoptosis, altering cell life versus death decisions in vitro and in vivo. Thus, TRAF2 sets a critical barrier for cell-extrinsic apoptosis commitment by tagging activated Caspase-8 with a K48-ubiquitin shutoff timer. These results may have important implications for Caspase regulation mechanisms.
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Cullin3-Based Polyubiquitination and p62-Dependent Aggregation of Caspase-8 Mediate Extrinsic Apoptosis Signaling
Cell, 2009Co-Authors: Zhaoyu Jin, David A Lawrence, Robert M. Pitti, Victoria C. Pham, Jennie R. Lill, Avi AshkenaziAbstract:Cell-surface death receptors such as DR4 and DR5 trigger apoptosis through a death-inducing signaling complex (DISC) that recruits the apical protease Caspase-8. Apoptosis commitment requires efficient activation and autocatalytic release of Caspase-8 into the cytoplasm to engage executioner Caspases. While DISC recruitment initiates Caspase-8 stimulation, full activation of the protease depends on further molecular aggregation events that are not fully understood. Here, we show that death receptor ligation induces polyubiquitination of Caspase-8, through a previously unknown interaction of the DISC with a cullin3 (CUL3)-based E3 ligase. CUL3-mediated Caspase-8 polyubiquitination required the RING box protein RBX1, whereas the deubiquitinase A20 reversed this modification. The ubiquitin-binding protein p62/sequestosome-1 promoted aggregation of CUL3-modified Caspase-8 within p62-dependent foci, leading to full activation and processing of the enzyme and driving commitment to cell death. These results identify a mechanism that positively controls apoptosis signaling by polyubiquitination and aggregation of a key initiator Caspase.
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death receptor recruitment of endogenous Caspase 10 and apoptosis initiation in the absence of Caspase 8
Journal of Biological Chemistry, 2001Co-Authors: Frank C Kischkel, David A Lawrence, Antoine Tinel, Heidi Leblanc, Arvind K Virmani, Peter Schow, Adi F Gazdar, John Blenis, David Arnott, Avi AshkenaziAbstract:Abstract Caspase-8 is believed to play an obligatory role in apoptosis initiation by death receptors, but the role of its structural relative, Caspase-10, remains controversial. Although earlier evidence implicated Caspase-10 in apoptosis signaling by CD95L and Apo2L/TRAIL, recent studies indicated that these death receptor ligands recruit Caspase-8 but not Caspase-10 to their death-inducing signaling complex (DISC) even in presence of abundant Caspase-10. We characterized a series of Caspase-10-specific antibodies and found that certain commercially available antibodies cross-react with HSP60, shedding new light on previous results. The majority of 55 lung and breast carcinoma cell lines expressed mRNA for both Caspase-8 and -10; however, immunoblot analysis revealed that Caspase-10 protein expression was more frequently absent than that of Caspase-8, suggesting a possible selective pressure against Caspase-10 production in cancer cells. In nontransfected cells expressing both Caspases, CD95L and Apo2L/TRAIL recruited endogenous Caspase-10 as well as Caspase-8 to their DISC, where both enzymes were proteolytically processed with similar kinetics. Caspase-10 recruitment required the adaptor FADD/Mort1, and Caspase-10 cleavage in vitrorequired DISC assembly, consistent with the processing of an apoptosis initiator. Cells expressing only one of the Caspases underwent ligand-induced apoptosis, indicating that each Caspase can initiate apoptosis independently of the other. Thus, apoptosis signaling by death receptors involves not only Caspase-8 but also Caspase-10, and both Caspases may have equally important roles in apoptosis initiation.