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Cell Sep 2022Drug-tolerant persister cells (persisters) evade apoptosis upon targeted and conventional cancer therapies and represent a major non-genetic barrier to effective cancer...
Drug-tolerant persister cells (persisters) evade apoptosis upon targeted and conventional cancer therapies and represent a major non-genetic barrier to effective cancer treatment. Here, we show that cells that survive treatment with pro-apoptotic BH3 mimetics display a persister phenotype that includes colonization and metastasis in vivo and increased sensitivity toward ferroptosis by GPX4 inhibition. We found that sublethal mitochondrial outer membrane permeabilization (MOMP) and holocytochrome c release are key requirements for the generation of the persister phenotype. The generation of persisters is independent of apoptosome formation and caspase activation, but instead, cytosolic cytochrome c induces the activation of heme-regulated inhibitor (HRI) kinase and engagement of the integrated stress response (ISR) with the consequent synthesis of ATF4, all of which are required for the persister phenotype. Our results reveal that sublethal cytochrome c release couples sublethal MOMP to caspase-independent initiation of an ATF4-dependent, drug-tolerant persister phenotype.
Topics: Animals; Apoptosis; Carrier Proteins; Caspases; Cytochromes c; Drug Resistance, Neoplasm; Humans; Mice; Mitochondria; Neoplasms
PubMed: 36055199
DOI: 10.1016/j.cell.2022.07.025 -
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 -
Advanced Science (Weinheim,... Oct 2022Chemotherapeutics remain the first choice for advanced gastric cancers (GCs). However, drug resistance and unavoidable severe toxicity lead to chemotherapy failure and...
Chemotherapeutics remain the first choice for advanced gastric cancers (GCs). However, drug resistance and unavoidable severe toxicity lead to chemotherapy failure and poor prognosis. Long noncoding RNAs (lncRNAs) play critical roles in tumor progression in many cancers, including GC. Here, through RNA screening, an apoptotic protease-activating factor 1 (APAF1)-binding lncRNA (ABL) that is significantly elevated in cancerous GC tissues and an independent prognostic factor for GC patients is identified. Moreover, ABL overexpression inhibits GC cell apoptosis and promotes GC cell survival and multidrug resistance in GC xenograft and organoid models. Mechanistically, ABL directly binds to the RNA-binding protein IGF2BP1 via its KH1/2 domain, and then IGF2BP1 further recognizes the METTL3-mediated m6A modification on ABL, which maintains ABL stability. In addition, ABL can bind to the WD1/WD2 domain of APAF1, which competitively prevent cytochrome c from interacting with APAF1, blocking apoptosome assembly and caspase-9/3 activation; these events lead to resistance to cell death in GC cells. Intriguingly, targeting ABL using encapsulated liposomal siRNA can significantly enhance the sensitivity of GC cells to chemotherapy. Collectively, the results suggest that ABL can be a potential prognostic biomarker and therapeutic target in GC.
Topics: Apoptosis; Apoptosomes; Apoptotic Protease-Activating Factor 1; Biomarkers; Caspase 9; Cytochromes c; Drug Resistance, Multiple; Humans; Methyltransferases; RNA, Long Noncoding; RNA, Small Interfering; Stomach Neoplasms
PubMed: 35975461
DOI: 10.1002/advs.202201889 -
Current Osteoporosis Reports Jun 2021In this review, we describe the biology of extracellular vesicles (EV) and how they contribute to bone-associated cancers. (Review)
Review
PURPOSE OF REVIEW
In this review, we describe the biology of extracellular vesicles (EV) and how they contribute to bone-associated cancers.
RECENT FINDINGS
Crosstalk between tumor and bone has been demonstrated to promote tumor and metastatic progression. In addition to direct cell-to-cell contact and soluble factors, such as cytokines, EVs mediate crosstalk between tumor and bone. EVs are composed of a heterogenous group of membrane-delineated vesicles of varying size range, mechanisms of formation, and content. These include apoptotic bodies, microvesicles, large oncosomes, and exosomes. EVs derived from primary tumors have been shown to alter bone remodeling and create formation of a pre-metastatic niche that favors development of bone metastasis. Similarly, EVs from marrow stromal cells have been shown to promote tumor progression. Additionally, EVs can act as therapeutic delivery vehicles due to their low immunogenicity and targeting specificity. EVs play critical roles in intercellular communication. Multiple classes of EVs exist based on size on mechanism of formation. In addition to a role in pathophysiology, EVs can be exploited as therapeutic delivery vehicles.
Topics: Bone Neoplasms; Cell Communication; Disease Progression; Extracellular Vesicles; Humans; Signal Transduction; Tumor Microenvironment
PubMed: 33638774
DOI: 10.1007/s11914-021-00668-w -
Development (Cambridge, England) Jul 2020Cell death is an important facet of animal development. In some developing tissues, death is the ultimate fate of over 80% of generated cells. Although recent studies... (Review)
Review
Cell death is an important facet of animal development. In some developing tissues, death is the ultimate fate of over 80% of generated cells. Although recent studies have delineated a bewildering number of cell death mechanisms, most have only been observed in pathological contexts, and only a small number drive normal development. This Primer outlines the important roles, different types and molecular players regulating developmental cell death, and discusses recent findings with which the field currently grapples. We also clarify terminology, to distinguish between developmental cell death mechanisms, for which there is evidence for evolutionary selection, and cell death that follows genetic, chemical or physical injury. Finally, we suggest how advances in understanding developmental cell death may provide insights into the molecular basis of developmental abnormalities and pathological cell death in disease.
Topics: Animals; Apoptosis; Apoptosomes; Autophagy; Caspases; Cell Death; Gene Expression Regulation, Developmental; Invertebrates; Mammals; Signal Transduction
PubMed: 32709690
DOI: 10.1242/dev.191882 -
Proceedings of the National Academy of... Dec 2023Mitochondrial apoptotic signaling cascades lead to the formation of the apoptosome, a 1.1-MDa heptameric protein scaffold that recruits and activates the caspase-9...
Mitochondrial apoptotic signaling cascades lead to the formation of the apoptosome, a 1.1-MDa heptameric protein scaffold that recruits and activates the caspase-9 protease. Once activated, caspase-9 cleaves and activates downstream effector caspases, triggering the onset of cell death through caspase-mediated proteolysis of cellular proteins. Failure to activate caspase-9 enables the evasion of programmed cell death, which occurs in various forms of cancer. Despite the critical apoptotic function of caspase-9, the structural mechanism by which it is activated on the apoptosome has remained elusive. Here, we used a combination of methyl-transverse relaxation-optimized NMR spectroscopy, protein engineering, and biochemical assays to study the activation of caspase-9 bound to the apoptosome. In the absence of peptide substrate, we observed that both caspase-9 and its isolated protease domain (PD) only very weakly dimerize with dissociation constants in the millimolar range. Methyl-NMR spectra of isotope-labeled caspase-9, within the 1.3-MDa native apoptosome complex or an engineered 480-kDa apoptosome mimic, reveal that the caspase-9 PD remains monomeric after recruitment to the scaffold. Binding to the apoptosome, therefore, organizes caspase-9 PDs so that they can rapidly and extensively dimerize only when substrate is present, providing an important layer in the regulation of caspase-9 activation. Our work highlights the unique role of NMR spectroscopy to structurally characterize protein domains that are flexibly tethered to large scaffolds, even in cases where the molecular targets are in excess of 1 MDa, as in the present example.
Topics: Caspase 9; Apoptosomes; Caspases; Apoptosis; Magnetic Resonance Spectroscopy; Caspase 3
PubMed: 38085782
DOI: 10.1073/pnas.2310944120 -
Journal of Personalized Medicine Aug 2022To adapt to the tumor environment or to escape chemotherapy, cancer cells rapidly reprogram their metabolism. The hallmark biochemical phenotype of cancer cells is the... (Review)
Review
To adapt to the tumor environment or to escape chemotherapy, cancer cells rapidly reprogram their metabolism. The hallmark biochemical phenotype of cancer cells is the shift in metabolic reprogramming towards aerobic glycolysis. It was thought that this metabolic shift to glycolysis alone was sufficient for cancer cells to meet their heightened energy and metabolic demands for proliferation and survival. Recent studies, however, show that cancer cells rely on glutamine, lipid, and mitochondrial metabolism for energy. Oncogenes and scavenging pathways control many of these metabolic changes, and several metabolic and tumorigenic pathways are post-transcriptionally regulated by microRNA (miRNAs). Genes that are directly or indirectly responsible for energy production in cells are either negatively or positively regulated by miRNAs. Therefore, some miRNAs play an oncogenic role by regulating the metabolic shift that occurs in cancer cells. Additionally, miRNAs can regulate mitochondrial calcium stores and energy metabolism, thus promoting cancer cell survival, cell growth, and metastasis. In the electron transport chain (ETC), miRNAs enhance the activity of apoptosis-inducing factor (AIF) and cytochrome c, and these apoptosome proteins are directed towards the ETC rather than to the apoptotic pathway. This review will highlight how miRNAs regulate the enzymes, signaling pathways, and transcription factors of cancer cell metabolism and mitochondrial calcium import/export pathways. The review will also focus on the metabolic reprogramming of cancer cells to promote survival, proliferation, growth, and metastasis with an emphasis on the therapeutic potential of miRNAs for cancer treatment.
PubMed: 36013278
DOI: 10.3390/jpm12081329 -
PLoS Pathogens Dec 2023Staphylococcus aureus is a dangerous pathogen that evolved refined immuno-evasive strategies to antagonize host immune responses. This involves the biogenesis of...
Staphylococcus aureus is a dangerous pathogen that evolved refined immuno-evasive strategies to antagonize host immune responses. This involves the biogenesis of death-effector deoxyribonucleosides, which kill infectious foci-penetrating macrophages. However, the exact mechanisms whereby staphylococcal death-effector deoxyribonucleosides and coupled imbalances of intracellular deoxyribonucleotide species provoke immune cell death remain elusive. Here, we report that S. aureus systematically promotes an overload of deoxyribonucleotides to trigger mitochondrial rupture in macrophages, a fatal event that induces assembly of the caspase-9-processing apoptosome and subsequent activation of the intrinsic pathway of apoptosis. Remarkably, genetic disruption of this cascade not only helps macrophages coping with death-effector deoxyribonucleoside-mediated cytotoxicity but also enhances their infiltration into abscesses thereby ameliorating pathogen control and infectious disease outcomes in laboratory animals. Combined with the discovery of protective alleles in human CASP9, these data highlight the role of mitochondria-centered apoptosis during S. aureus infection and suggest that gene polymorphisms may shape human susceptibility toward a predominant pathogen.
Topics: Animals; Humans; Staphylococcus aureus; Nucleotides; Phagocytes; Cell Death; Apoptosis; Mitochondria; Deoxyribonucleosides
PubMed: 38157331
DOI: 10.1371/journal.ppat.1011892 -
Apoptosis : An International Journal on... Oct 2020Apoptosis plays a major role in development, tissue renewal and the progression of degenerative diseases. Studies on various types of mammalian cells reported a...
Apoptosis plays a major role in development, tissue renewal and the progression of degenerative diseases. Studies on various types of mammalian cells reported a pro-apoptotic function of acetylcholinesterase (AChE), particularly in the formation of the apoptosome and the degradation of nuclear DNA. While three AChE splice variants are present in mammals, invertebrates typically express two ache genes that code for a synaptically located protein and a protein with non-synaptic functions respectively. In order to investigate a potential contribution of AChE to apoptosis in insects, we selected the migratory locust Locusta migratoria. We established primary neuronal cultures of locust brains and characterized apoptosis progression in vitro. Dying neurons displayed typical characteristics of apoptosis, including caspase-activation, nuclear condensation and DNA fragmentation visualized by TUNEL staining. Addition of the AChE inhibitors neostigmine and territrem B reduced apoptotic cell death under normal culture conditions. Moreover, both inhibitors completely suppressed hypoxia-induced neuronal cell death. Exposure of live animals to severe hypoxia moderately increased the expression of ace-1 in locust brains in vivo. Our results indicate a previously unreported role of AChE in insect apoptosis that parallels the pro-apoptotic role in mammalian cells. This similarity adds to the list of apoptotic mechanisms shared by mammals and insects, supporting the hypothesized existence of an ancient, complex apoptosis regulatory network present in common ancestors of vertebrates and insects.
Topics: Acetylcholinesterase; Animals; Apoptosis; Brain; Cell Death; Cell Nucleus; DNA Fragmentation; Grasshoppers; Hypoxia; Insecta; Neurons; Peptidyl-Dipeptidase A
PubMed: 32761307
DOI: 10.1007/s10495-020-01630-4 -
ACS Omega Sep 2021The molecular mechanism of apoptosome activation through conformational changes of Apaf-1 auto-inhibited form remains largely enigmatic. The crystal structure of Apaf-1...
The molecular mechanism of apoptosome activation through conformational changes of Apaf-1 auto-inhibited form remains largely enigmatic. The crystal structure of Apaf-1 suggests that some ionic bonds, including the bond between K192 and D616, are critical for the preservation of the inactive "closed" form of Apaf-1. Here, a split luciferase complementation assay was used to monitor the effect of disrupting this ionic bond on apoptosome activation and caspase-3 activity in cells. The K192E mutation, predicted to disrupt the ionic interaction with D616, increased apoptosome formation and caspase activity, suggesting that this mutation favors the "open"/active form of Apaf-1. However, mutation of D616 to alanine or lysine had different effects. While both mutants favored apoptosome formation such as K192E, D616K cannot activate caspases and D616A activates caspases poorly, and not as well as wild-type Apaf-1. Thus, our data show that the ionic bond between K192 and D616 is critical for maintaining the closed form of Apaf-1 and that disrupting the interaction enhances apoptosome formation. However, our data also reveal that after apoptosome formation, D616 and K192 play a previously unsuspected role in caspase activation. The molecular explanation for this observation is yet to be elucidated.
PubMed: 34514227
DOI: 10.1021/acsomega.1c02274