scholarly journals Cryo-EM structural analysis of FADD:Caspase-8 complexes defines the catalytic dimer architecture for co-ordinated control of cell fate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joanna L. Fox ◽  
Michelle A. Hughes ◽  
Xin Meng ◽  
Nikola A. Sarnowska ◽  
Ian R. Powley ◽  
...  
Keyword(s):  
Cell Death ◽  
Structural Analysis ◽  
Cell Fate ◽  
Catalytic Domain ◽  
Caspase 8 ◽  
Type I ◽  
Signaling Complex ◽  
Catalytic Domains ◽  
Regulated Cell Death ◽  
Death Effector

AbstractRegulated cell death is essential in development and cellular homeostasis. Multi-protein platforms, including the Death-Inducing Signaling Complex (DISC), co-ordinate cell fate via a core FADD:Caspase-8 complex and its regulatory partners, such as the cell death inhibitor c-FLIP. Here, using electron microscopy, we visualize full-length procaspase-8 in complex with FADD. Our structural analysis now reveals how the FADD-nucleated tandem death effector domain (tDED) helical filament is required to orientate the procaspase-8 catalytic domains, enabling their activation via anti-parallel dimerization. Strikingly, recruitment of c-FLIPS into this complex inhibits Caspase-8 activity by altering tDED triple helix architecture, resulting in steric hindrance of the canonical tDED Type I binding site. This prevents both Caspase-8 catalytic domain assembly and tDED helical filament elongation. Our findings reveal how the plasticity, composition and architecture of the core FADD:Caspase-8 complex critically defines life/death decisions not only via the DISC, but across multiple key signaling platforms including TNF complex II, the ripoptosome, and RIPK1/RIPK3 necrosome.

scholarly journals Biomarkers of Radiotherapy-Induced Immunogenic Cell Death

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 930
Author(s):  
Rianne D. W. Vaes ◽  
Lizza E. L. Hendriks ◽  
Marc Vooijs ◽  
Dirk De Ruysscher
Keyword(s):  
Cell Death ◽  
Immune Responses ◽  
Tumor Cells ◽  
Immunogenic Cell Death ◽  
Type I ◽  
Future Studies ◽  
Regulated Cell Death ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
Potential Biomarkers

Radiation therapy (RT) can induce an immunogenic variant of regulated cell death that can initiate clinically relevant tumor-targeting immune responses. Immunogenic cell death (ICD) is accompanied by the exposure and release of damage-associated molecular patterns (DAMPs), chemokine release, and stimulation of type I interferon (IFN-I) responses. In recent years, intensive research has unraveled major mechanistic aspects of RT-induced ICD and has resulted in the identification of immunogenic factors that are released by irradiated tumor cells. However, so far, only a limited number of studies have searched for potential biomarkers that can be used to predict if irradiated tumor cells undergo ICD that can elicit an effective immunogenic anti-tumor response. In this article, we summarize the available literature on potential biomarkers of RT-induced ICD that have been evaluated in cancer patients. Additionally, we discuss the clinical relevance of these findings and important aspects that should be considered in future studies.

scholarly journals The pseudokinase MLKL activates PAD4-dependent NET formation in necroptotic neutrophils

2018 ◽  
Vol 11 (546) ◽  
pp. eaao1716 ◽  
Author(s):  
Akshay A. D’Cruz ◽  
Mary Speir ◽  
Meghan Bliss-Moreau ◽  
Sylvia Dietrich ◽  
Shu Wang ◽  
...  
Keyword(s):  
Cell Death ◽  
Kinase Domain ◽  
Neutrophil Extracellular Trap ◽  
Human Neutrophils ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Dependent Activity ◽  
Mrsa Infection ◽  
Death Effector ◽  
Net Release

Neutrophil extracellular trap (NET) formation can generate short-term, functional anucleate cytoplasts and trigger loss of cell viability. We demonstrated that the necroptotic cell death effector mixed lineage kinase domain–like (MLKL) translocated from the cytoplasm to the plasma membrane and stimulated downstream NADPH oxidase–independent ROS production, loss of cytoplasmic granules, breakdown of the nuclear membrane, chromatin decondensation, histone hypercitrullination, and extrusion of bacteriostatic NETs. This process was coordinated by receptor-interacting protein kinase-1 (RIPK1), which activated the caspase-8–dependent apoptotic or RIPK3/MLKL-dependent necroptotic death of mouse and human neutrophils. Genetic deficiency of RIPK3 and MLKL prevented NET formation but did not prevent cell death, which was because of residual caspase-8–dependent activity. Peptidylarginine deiminase 4 (PAD4) was activated downstream of RIPK1/RIPK3/MLKL and was required for maximal histone hypercitrullination and NET extrusion. This work defines a distinct signaling network that activates PAD4-dependent NET release for the control of methicillin-resistant Staphylococcus aureus (MRSA) infection.

Functional CD95 ligand and CD95 death-inducing signaling complex in activation-induced cell death and doxorubicin-induced apoptosis in leukemic T cells

Blood ◽  
2000 ◽  
Vol 95 (1) ◽  
pp. 301-308 ◽  
Author(s):  
Simone Fulda ◽  
Gudrun Strauss ◽  
Eric Meyer ◽  
Klaus-Michael Debatin
Keyword(s):  
T Cells ◽  
Cell Death ◽  
Leukemia Cell Line ◽  
Receptor Interaction ◽  
Caspase 8 ◽  
Drug Induced ◽  
Signaling Complex ◽  
Cd95 Ligand ◽  
Activation Induced Cell Death ◽  
Induced Apoptosis

Abstract Activation-induced cell death (AICD) in T cells is mediated by CD95 ligand (CD95L)/receptor interaction, which has also been implicated in apoptosis induction by some anticancer agents. In this article we show that both anti-CD3-triggering (AICD) and doxorubicin treatment led to the production of a functionally active CD95L in the CD3+/T-cell receptor-positive (TCR+) T leukemia cell line H9. CD95L-expressing H9 cells killed CD95-sensitive J16 or CEM target cells, but not CD95-resistant CEM or J16 cells overexpressing dominant negative FADD (J16/FADD-DN). By immunoprecipitation, CD95L was physically bound to CD95, suggesting that AICD and doxorubicin-induced apoptosis involve CD95L-mediated CD95 aggregation, thereby triggering the CD95 death pathway. CD95 aggregation was associated with the recruitment of FADD and caspase-8 to the CD95 receptor to form the CD95 death-inducing signaling complex (DISC), resulting in caspase-8 activation and cleavage of the effector caspase-3 and PARP. Blocking of the CD95L/receptor interaction by antagonistic antibodies to CD95 or to CD95L also blocked AICD and inhibited the early phase of doxorubicin-induced apoptosis, though cell death induced by doxorubicin eventually proceeded in a CD95-independent manner. These findings may explain some conflicting data on the role of death receptor systems in drug-induced apoptosis. Thus, in cells with an inducible CD95 receptor/ligand system, drug-induced apoptosis may be mediated by CD95L-initiated DISC formation and activation of downstream effector programs similar to AICD in T cells. (Blood. 2000;95:301-308)

Functional CD95 ligand and CD95 death-inducing signaling complex in activation-induced cell death and doxorubicin-induced apoptosis in leukemic T cells

Blood ◽  
2000 ◽  
Vol 95 (1) ◽  
pp. 301-308 ◽  
Author(s):  
Simone Fulda ◽  
Gudrun Strauss ◽  
Eric Meyer ◽  
Klaus-Michael Debatin
Keyword(s):  
T Cells ◽  
Cell Death ◽  
Leukemia Cell Line ◽  
Receptor Interaction ◽  
Caspase 8 ◽  
Drug Induced ◽  
Signaling Complex ◽  
Cd95 Ligand ◽  
Activation Induced Cell Death ◽  
Induced Apoptosis

Activation-induced cell death (AICD) in T cells is mediated by CD95 ligand (CD95L)/receptor interaction, which has also been implicated in apoptosis induction by some anticancer agents. In this article we show that both anti-CD3-triggering (AICD) and doxorubicin treatment led to the production of a functionally active CD95L in the CD3+/T-cell receptor-positive (TCR+) T leukemia cell line H9. CD95L-expressing H9 cells killed CD95-sensitive J16 or CEM target cells, but not CD95-resistant CEM or J16 cells overexpressing dominant negative FADD (J16/FADD-DN). By immunoprecipitation, CD95L was physically bound to CD95, suggesting that AICD and doxorubicin-induced apoptosis involve CD95L-mediated CD95 aggregation, thereby triggering the CD95 death pathway. CD95 aggregation was associated with the recruitment of FADD and caspase-8 to the CD95 receptor to form the CD95 death-inducing signaling complex (DISC), resulting in caspase-8 activation and cleavage of the effector caspase-3 and PARP. Blocking of the CD95L/receptor interaction by antagonistic antibodies to CD95 or to CD95L also blocked AICD and inhibited the early phase of doxorubicin-induced apoptosis, though cell death induced by doxorubicin eventually proceeded in a CD95-independent manner. These findings may explain some conflicting data on the role of death receptor systems in drug-induced apoptosis. Thus, in cells with an inducible CD95 receptor/ligand system, drug-induced apoptosis may be mediated by CD95L-initiated DISC formation and activation of downstream effector programs similar to AICD in T cells. (Blood. 2000;95:301-308)

scholarly journals Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress

2021 ◽  
Vol 9 (10) ◽  
pp. 2152
Author(s):  
Brittany Friedson ◽  
Katrina F. Cooper
Keyword(s):  
Cell Death ◽  
Rna Polymerase Ii ◽  
Cell Fate ◽  
Ubiquitin Proteasome System ◽  
Mitochondrial Morphology ◽  
Atp Production ◽  
Cell Fate Decisions ◽  
Regulated Cell Death ◽  
Cyclin C ◽  
Convergence Point

The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.

scholarly journals Caspases: the executioners of apoptosis

1997 ◽  
Vol 326 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Gerald M. COHEN
Keyword(s):  
Cell Death ◽  
Morphological Changes ◽  
Cysteine Proteases ◽  
Death Receptors ◽  
Small Subunit ◽  
Caspase 8 ◽  
Death Domain ◽  
Interacting Protein ◽  
Death Effector ◽  
Caspase 2

Apoptosis is a major form of cell death, characterized initially by a series of stereotypic morphological changes. In the nematode Caenorhabditis elegans, the gene ced-3 encodes a protein required for developmental cell death. Since the recognition that CED-3 has sequence identity with the mammalian cysteine protease interleukin-1β-converting enzyme (ICE), a family of at least 10 related cysteine proteases has been identified. These proteins are characterized by almost absolute specificity for aspartic acid in the P1 position. All the caspases (ICE-like proteases) contain a conserved QACXG (where X is R, Q or G) pentapeptide active-site motif. Caspases are synthesized as inactive proenzymes comprising an N-terminal peptide (prodomain) together with one large and one small subunit. The crystal structures of both caspase-1 and caspase-3 show that the active enzyme is a heterotetramer, containing two small and two large subunits. Activation of caspases during apoptosis results in the cleavage of critical cellular substrates, including poly(ADP-ribose) polymerase and lamins, so precipitating the dramatic morphological changes of apoptosis. Apoptosis induced by CD95 (Fas/APO-1) and tumour necrosis factor activates caspase-8 (MACH/FLICE/Mch5), which contains an N-terminus with FADD (Fas-associating protein with death domain)-like death effector domains, so providing a direct link between cell death receptors and the caspases. The importance of caspase prodomains in the regulation of apoptosis is further highlighted by the recognition of adapter molecules, such as RAIDD [receptor-interacting protein (RIP)-associated ICH-1/CED-3-homologous protein with a death domain]/CRADD (caspase and RIP adapter with death domain), which binds to the prodomain of caspase-2 and recruits it to the signalling complex. Cells undergoing apoptosis following triggering of death receptors execute the death programme by activating a hierarchy of caspases, with caspase-8 and possibly caspase-10 being at or near the apex of this apoptotic cascade.

scholarly journals RIP1-dependent linear and nonlinear recruitments of caspase-8 and RIP3 respectively to necrosome specify distinct cell death outcomes

2021 ◽  
Author(s):  
Xiang Li ◽  
Chuan-Qi Zhong ◽  
Rui Wu ◽  
Xiaozheng Xu ◽  
Zhang-Hua Yang ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Fate ◽  
Basis Sets ◽  
Nonlinear Dependence ◽  
Caspase 8 ◽  
Cell Fate Decisions ◽  
Distinct Cell ◽  
Quantitative Understanding ◽  
Linear And Nonlinear ◽  
Dynamic Interplay

AbstractThere remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways. By employing the SWATH-MS technique, we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes. Combining SWATH-MS-based network modeling and experimental validation, we found that when RIP1 level is below ~1000 molecules/cell (mpc), the cell solely undergoes TRADD-dependent apoptosis. When RIP1 is above ~1000 mpc, pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount, which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical observations that RIP1 is required for necroptosis but its increase down-regulates necroptosis. Higher amount of RIP1 (>~46,000 mpc) suppresses apoptosis, leading to necroptosis alone. The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic. Our study provides a resource for encoding the complexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes, enabling RIP1 to play diverse roles in governing cell fate decisions.

scholarly journals Pkh1p-Ypk1p and Pkh1p-Sch9p Pathways Are Activated by Acetic Acid to Induce a Mitochondrial-Dependent Regulated Cell Death

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
António Rego ◽  
Filipa Mendes ◽  
Vítor Costa ◽  
Susana Rodrigues Chaves ◽  
Manuela Côrte-Real
Keyword(s):  
Cell Death ◽  
Acetic Acid ◽  
Cell Survival ◽  
Cell Fate ◽  
Negative Regulator ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Outer Membrane Permeabilization ◽  
Double Deletion ◽  
Regulated Cell Death ◽  
Single Deletion

The yeast Saccharomyces cerevisiae undergoes a mitochondrial-dependent regulated cell death (RCD) exhibiting typical markers of mammalian apoptosis. We have previously shown that ceramide production contributes to RCD induced by acetic acid and is involved in mitochondrial outer membrane permeabilization and cytochrome c release, especially through hydrolysis of complex sphingolipids catalyzed by Isc1p. Recently, we also showed that Sch9p regulates the translocation of Isc1p from the endoplasmic reticulum into mitochondria, perturbing sphingolipid balance and determining cell fate. In this study, we addressed the role of other signaling proteins in acetic acid-induced RCD. We found that single deletion of PKH1 or YPK1, as shown for SCH9 and ISC1, leads to an increase in cell survival in response to acetic acid and that Pkh1/2p-dependent phosphorylation of Ypk1p and Sch9p increases under these conditions. These results indicate that Pkh1p regulates acetic acid-induced RCD through Ypk1p and Sch9p. In addition, our results suggest that Pkh1p-Ypk1p is necessary for isc1Δ resistance to acetic acid-induced RCD. Moreover, double deletion of ISC1 and PKH1 has a drastic effect on cell survival associated with increased ROS accumulation and release of cytochrome c, which is counteracted by overexpression of the PKA pathway negative regulator PDE2. Overall, our results suggest that Pkh1p-Ypk1p and Pkh1p-Sch9p pathways contribute to RCD induced by acetic acid.

scholarly journals Heterologous Expression and Auto-Activation of Human Pro-Inflammatory Caspase-1 in Saccharomyces cerevisiae and Comparison to Caspase-8

2021 ◽  
Vol 12 ◽  
Author(s):  
Marta Valenti ◽  
María Molina ◽  
Víctor J. Cid
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Death ◽  
Heterologous Expression ◽  
Cysteine Proteases ◽  
Intrinsic Activity ◽  
Caspase 8 ◽  
Caspase 1 ◽  
Death Effector ◽  
Human Caspase

Caspases are a family of cysteine proteases that play an essential role in inflammation, apoptosis, cell death, and development. Here we delve into the effects caused by heterologous expression of human caspase-1 in the yeast Saccharomyces cerevisiae and compare them to those of caspase-8. Overexpression of both caspases in the heterologous model led to their activation and caused mitochondrial hyperpolarization, damage to different organelles, and cell death. All these effects were dependent on their protease activity, and caspase-8 was more aggressive than caspase-1. Growth arrest could be at least partially explained by dysfunction of the actin cytoskeleton as a consequence of the processing of the yeast Bni1 formin, which we identify here as a likely direct substrate of both caspases. Through the modulation of the GAL1 promoter by using different galactose:glucose ratios in the culture medium, we have established a scenario in which caspase-1 is sufficiently expressed to become activated while yeast growth is not impaired. Finally, we used the yeast model to explore the role of death-fold domains (DD) of both caspases in their activity. Peculiarly, the DDs of either caspase showed an opposite involvement in its intrinsic activity, as the deletion of the caspase activation and recruitment domain (CARD) of caspase-1 enhanced its activity, whereas the deletion of the death effector domain (DED) of caspase-8 diminished it. We show that caspase-1 is able to efficiently process its target gasdermin D (GSDMD) when co-expressed in yeast. In sum, we propose that S. cerevisiae provides a manageable tool to explore caspase-1 activity and structure–function relationships.

scholarly journals Blunted Fas signaling favors RIPK1-driven neutrophil necroptosis in critically ill COVID-19 patients

2021 ◽  
Author(s):  
Tiziano A Schweizer ◽  
Srikanth Mairpady Shambat ◽  
Clement Vulin ◽  
Sylvia Hoeller ◽  
Claudio Acevedo ◽  
...  
Keyword(s):  
Cell Death ◽  
Disease Severity ◽  
Critically Ill ◽  
Cytokine Profile ◽  
Caspase 8 ◽  
Potential Therapeutic Target ◽  
Regulated Cell Death ◽  
Cell Death Program ◽  
Fas Signaling ◽  
The Impact

Critically ill COVID-19 patients are characterized by a severely dysregulated cytokine profile and elevated neutrophil counts, which are thought to contribute to disease severity. However, to date it remains unclear how neutrophils contribute to pathophysiology during COVID-19. Here, we assessed the impact of the dysregulated cytokine profile on the tightly regulated cell death program of neutrophils. We show that in a subpopulation of neutrophils, canonical apoptosis was skewed towards rapidly occurring necroptosis. This phenotype was characterized by abrogated caspase-8 activity and increased RIPK1 levels, favoring execution of necroptosis via the RIPK1-RIPK3-MLKL axis, as further confirmed in COVID-19 biopsies. Moreover, reduction of sFas-L levels in COVID-19 patients and hence decreased signaling to Fas directly increased RIPK1 levels and correlated with disease severity. Our results suggest an important role for Fas signaling in the regulation of cell death program ambiguity via the ripoptosome in neutrophils during COVID-19 and a potential therapeutic target to curb inflammation and thus influence disease severity and outcome.

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