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Trends in Biochemical Sciences Jun 2001The caspase family of cysteine proteases have emerged as central regulators of apoptosis. Diverse cellular stresses trigger caspase activation by promoting release of... (Review)
Review
The caspase family of cysteine proteases have emerged as central regulators of apoptosis. Diverse cellular stresses trigger caspase activation by promoting release of mitochondrial components, including cytochrome c, into the cytoplasm. In turn, cytochrome c promotes the assembly of a caspase-activating complex termed the apoptosome. In this article, the apoptosome and its role in life and death decisions of cells are discussed.
Topics: Animals; Apoptosis; Caenorhabditis elegans; Caspases; Cytochrome c Group; Enzyme Activation; Mitochondria; Organelles; Proto-Oncogene Proteins c-bcl-2
PubMed: 11406413
DOI: 10.1016/s0968-0004(01)01844-8 -
Cell Death and Differentiation Jan 2003
Review
Topics: Animals; Apoptosis; Apoptotic Protease-Activating Factor 1; Caspases; Cytochromes c; Eukaryotic Cells; Humans; Macromolecular Substances; Mitochondria; Proteins; Signal Transduction
PubMed: 12655291
DOI: 10.1038/sj.cdd.4401166 -
Archives of Biochemistry and Biophysics Mar 2018Apaf-1 is a cytosolic multi-domain protein in the apoptosis regulatory network. When cytochrome c releases from mitochondria; it binds to WD-40 repeats of Apaf-1...
Apaf-1 is a cytosolic multi-domain protein in the apoptosis regulatory network. When cytochrome c releases from mitochondria; it binds to WD-40 repeats of Apaf-1 molecule and induces oligomerization of Apaf-1. Here in, a split luciferase assay was used to compare apoptosome formation in cell-free and cell-based systems. This assay uses Apaf-1 tagged with either N-terminal fragment or C-terminal fragment of P. pyralis luciferase. In cell based-system, the apoptosome formation is induced inside the cells which express Apaf-1 tagged with complementary fragments of luciferase while in cell-free system, the apoptosome formation is induced in extracts of the cells. In cell-free system, cytochrome c dependent luciferase activity was observed with full length Apaf-1. However, luciferase activity due to apoptosome formation was much higher in cell based system compared to cell-free system. The truncated Apaf-1 which lacks WD-40 repeats (ΔApaf-1) interacted with endogenous Apaf-1 in a different fashion compared to native form as confirmed by different retention time of eluate in gel filtration and binding to affinity column. The interactions between endogenous Apaf-1 and ΔApaf-1 is stronger than its interaction with native exogenous Apaf-1 as indicated by dominant negative effect of ΔApaf-1 on caspase-3 processing.
Topics: Apoptosis; Apoptosomes; Apoptotic Protease-Activating Factor 1; Biopolymers; Caspase 3; Caspase 9; Cell-Free System; Chromatography, Affinity; Chromatography, Gel; Enzyme Activation; HEK293 Cells; Humans; Luciferases; Protein Binding; Proteolysis; WD40 Repeats
PubMed: 29410086
DOI: 10.1016/j.abb.2018.01.017 -
Life Science Alliance Sep 2023In , onset of programmed cell death is marked with the activation of CED-3, a process that requires assembly of the CED-4 apoptosome. Activated CED-3 forms a holoenzyme...
In , onset of programmed cell death is marked with the activation of CED-3, a process that requires assembly of the CED-4 apoptosome. Activated CED-3 forms a holoenzyme with the CED-4 apoptosome to cleave a wide range of substrates, leading to irreversible cell death. Despite decades of investigations, the underlying mechanism of CED-4-facilitated CED-3 activation remains elusive. Here, we report cryo-EM structures of the CED-4 apoptosome and three distinct CED-4/CED-3 complexes that mimic different activation stages for CED-3. In addition to the previously reported octamer in crystal structures, CED-4, alone or in complex with CED-3, exists in multiple oligomeric states. Supported by biochemical analyses, we show that the conserved CARD-CARD interaction promotes CED-3 activation, and initiation of programmed cell death is regulated by the dynamic organization of the CED-4 apoptosome.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Apoptosomes; Apoptosis
PubMed: 37402593
DOI: 10.26508/lsa.202302056 -
Molecular Biology of the Cell May 2023The actin cytoskeleton is a ubiquitous participant in cellular functions that maintain viability, but how it controls programmed cell death is not well understood. Here...
The actin cytoskeleton is a ubiquitous participant in cellular functions that maintain viability, but how it controls programmed cell death is not well understood. Here we show that in response to DNA damage, human cells form a juxtanuclear F-actin-rich territory that coordinates the organized progression of apoptosome assembly to caspase activation. This cytoskeletal compartment is created by the actin nucleation factors JMY, WHAMM, and the Arp2/3 complex, and it excludes proteins that inhibit JMY and WHAMM activity. Within the territory, mitochondria undergo outer membrane permeabilization and JMY localization overlaps with punctate structures containing the core apoptosome components cytochrome and Apaf-1. The F-actin-rich area also encompasses initiator caspase-9 and clusters of a cleaved form of executioner caspase-3 but restricts accessibility of the caspase inhibitor XIAP. The clustering and potency of caspase-3 activation are positively regulated by the amount of actin polymerized by JMY and WHAMM. These results indicate that JMY-mediated actin reorganization functions in apoptotic signaling by coupling the biogenesis of apoptosomes to the localized processing of caspases.
Topics: Humans; Actins; Caspase 3; Apoptosomes; Apoptosis; Caspases; Actin Cytoskeleton; DNA Damage; Membrane Proteins; Microtubule-Associated Proteins
PubMed: 36920061
DOI: 10.1091/mbc.E22-04-0119 -
Cell Apr 2010The mechanism by which the apoptosome activates caspases during apoptosis has been controversial. Qi et al. (2010) now present a crystal structure of a funnel-shaped...
The mechanism by which the apoptosome activates caspases during apoptosis has been controversial. Qi et al. (2010) now present a crystal structure of a funnel-shaped octameric apoptosome complex from the nematode Caenorhabditis elegans that challenges currently held assumptions about the human apoptosome structure.
PubMed: 20434981
DOI: 10.1016/j.cell.2010.04.015 -
Cell Death and Differentiation Oct 2020The execution phase of apoptosis is a critical process in programmed cell death in response to a multitude of cellular stresses. A crucial component of this pathway is...
The execution phase of apoptosis is a critical process in programmed cell death in response to a multitude of cellular stresses. A crucial component of this pathway is the apoptosome, a platform for the activation of pro-caspase 9 (PC9). Recent findings have shown that autocleavage of PC9 to Caspase 9 (C9) p35/p12 not only permits XIAP-mediated C9 inhibition but also temporally shuts down apoptosome activity, forming a molecular timer. In order to delineate the combined contributions of XIAP and the apoptosome molecular timer to apoptosis execution we utilised a systems modelling approach. We demonstrate that cooperative recruitment of PC9 to the apoptosome, based on existing PC9-apoptosome interaction data, is important for efficient formation of PC9 homodimers, autocatalytic cleavage and dual regulation by XIAP and the molecular timer across biologically relevant PC9 and APAF1 concentrations. Screening physiologically relevant concentration ranges of apoptotic proteins, we discovered that the molecular timer can prevent apoptosis execution in specific scenarios after complete or partial mitochondrial outer membrane permeabilisation (MOMP). Furthermore, its ability to prevent apoptosis is intricately tied to a synergistic combination with XIAP. Finally, we demonstrate that simulations of these processes are prognostic of survival in stage III colorectal cancer and that the molecular timer may promote apoptosis resistance in a subset of patients. Based on our findings, we postulate that the physiological function of the molecular timer is to aid XIAP in the shutdown of caspase-mediated apoptosis execution. This shutdown potentially facilitates switching to pro-inflammatory caspase-independent responses subsequent to Bax/Bak pore formation.
Topics: Apoptosis; Caspase 9; Colorectal Neoplasms; Humans; Mitochondria; Mitochondrial Membranes; X-Linked Inhibitor of Apoptosis Protein
PubMed: 32341447
DOI: 10.1038/s41418-020-0545-9 -
Biochemistry. Biokhimiia Feb 2020Cytotoxic T lymphocytes and natural killer cells eliminate infected cells from the organism by triggering programmed cell death (apoptosis). The contents of the lytic... (Review)
Review
Cytotoxic T lymphocytes and natural killer cells eliminate infected cells from the organism by triggering programmed cell death (apoptosis). The contents of the lytic granules of killer cells, including pore-forming proteins perforins and proteolytic enzymes granzymes, are released with the following penetration of the released proteins into the target cells. Granzyme B initiates mitochondria-dependent apoptosis via (i) proapoptotic Bid protein, (ii) Mcl-1 and Bim proteins, or (iii) p53 protein. As a result, cytochrome c is released from the mitochondria into the cytoplasm, causing formation of apoptosomes that initiate the proteolytic cascade of caspase activation. Granzymes M, H, and F cause cell death accompanied by the cytochrome c release from the mitochondria. Granzyme A induces generation of reactive oxygen species (ROS), which promotes translocation of the endoplasmic reticulum-associated SET complex to the nucleus where it is cleaved by granzyme A, leading to the activation of nucleases that catalyze single-strand DNA breaks. Granzymes A and B penetrate into the mitochondria and cleave subunits of the respiratory chain complex I. One of the complex I subunits is also a target for caspase-3. Granzyme-dependent damage to complex I leads to the ROS generation and cell death.
Topics: Animals; Cell Death; Granzymes; Humans; Mitochondria; Reactive Oxygen Species
PubMed: 32093590
DOI: 10.1134/S0006297920020017 -
Molecular Cell Apr 2006The apical protease of the human intrinsic apoptotic pathway, caspase-9, is activated in a polymeric activation platform known as the apoptosome. The mechanism has been...
The apical protease of the human intrinsic apoptotic pathway, caspase-9, is activated in a polymeric activation platform known as the apoptosome. The mechanism has been debated, and two contrasting hypotheses have been suggested. One of these postulates an allosteric activation of monomeric caspase-9; the other postulates a dimer-driven assembly at the surface of the apoptosome--the "induced proximity" model. We show that both Hofmeister salts and a reconstituted mini-apoptosome activate caspase-9 by a second-order process, compatible with a conserved dimer-driven process. Significantly, replacement of the recruitment domain of the apical caspase of the extrinsic apoptotic pathway, caspase-8, by that of caspase-9 allows activation of this hybrid caspase by the apoptosome. Consequently, apical caspases can be activated simply by directing their zymogens to the apoptosome, ruling out the requirement for allosteric activation and supporting an induced proximity dimerization model for apical caspase activation in vivo.
Topics: Apoptosis; Apoptotic Protease-Activating Factor 1; Caspase 8; Caspase 9; Caspases; Catalysis; Cell Line; Citrates; Dimerization; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Precursors; Humans; Intracellular Signaling Peptides and Proteins; Kinetics; Models, Biological; Protein Structure, Tertiary; Proteins; Recombinant Proteins; Sodium Citrate; Substrate Specificity
PubMed: 16630894
DOI: 10.1016/j.molcel.2006.03.009 -
Journal of Cellular and Molecular... 2003Different cellular pathways can lead to apoptosis. Apaf1 is the molecular core of the apoptosome, a multiproteic complex mediating the so-called mitochondrial pathway of... (Review)
Review
Different cellular pathways can lead to apoptosis. Apaf1 is the molecular core of the apoptosome, a multiproteic complex mediating the so-called mitochondrial pathway of cell death. The importance of this pathway during development has been clearly demonstrated by knocking out key genes. Also, the relevance of Apaf1 dosage during development has been recently underlined. Moreover, a growing body of evidences seems to point out a possible role of the mitochondria-dependent apoptosis in different pathologies. In particular, we discuss here some recent evidences regarding the putative role of the apoptosome in neurodegeneration and cancer.
Topics: Animals; Apoptosis; Apoptotic Protease-Activating Factor 1; Caspases; Enzyme Activation; Gene Dosage; Humans; Macromolecular Substances; Neoplasms; Nerve Tissue Proteins; Neurodegenerative Diseases; Proteins
PubMed: 12767258
DOI: 10.1111/j.1582-4934.2003.tb00199.x