Apoptosis regulation by subcellular relocation of caspases.
Ontology highlight
ABSTRACT:
SUBMITTER: Prokhorova EA
PROVIDER: S-EPMC6093910 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Hydrogen sulfide has been implicated in a large number of physiological processes including cell survival and death, encouraging research into its mechanisms of action and therapeutic potential. Recent studies suggest that the cellular effects of hydrogen sulfide are mediated in part by sulfane sulfur species including persulfides and polysulfides. In the present study, we investigated the apoptosis-modulating effects of polysulfides, in particular, in relation to the caspase cascade that mediates the intrinsic apoptotic pathway. Biochemical analyses revealed that organic or synthetic polysulfides strongly and rapidly inhibited the enzymatic activity of caspase-3, a major effector protease in apoptosis. Enzyme inhibition was attributed to persulfidation of the catalytic cysteine. In apoptotically stimulated HeLa cells, short-term exposure to polysulfides triggered the persulfidation and deactivation of cleaved caspae-3. These effects were antagonized by the thioredoxin/thioredoxin reductase system (Trx/TrxR). Indeed, Trx/TrxR restored the activity of polysulfide-inactivated caspase-3 in vitro, and inhibition of TrxR potentiated polysulfidemediated suppression of caspase-3 activity in situ. We further found that under conditions of low TrxR activity, early cell exposure to polysulfides lead to enhanced persulfidation of initiator caspase-9, resulting in decreased apoptosis. Beyond these observations, we show that the proenzymes, procaspase-3/-9, are basally persulfidated in resting (unstimulated) cells and become depersulfidated during their processing and activation. Inhibition of TrxR attenuated the depersulfidation and activation of caspase-9. Taken together, our results reveal that polysulfides target the caspase-9/3 cascade to suppress cancer cell apoptosis. The findings further suggest that Trx/TrxR-mediated depersulfidation may regulate caspase-dependent cell death.
2020-02-18 | PXD017144 | Pride
Project description: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-1 beta-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. Capases 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.
| S-EPMC1218630 | biostudies-other
Project description:Nonsense-mediated mRNA decay (NMD) is an mRNA surveillance mechanism that plays integral roles in eliminating mRNAs with premature termination codons to prevent the synthesis of truncated proteins that could be pathogenic. One response to the accumulation of detrimental proteins is apoptosis, which involves the activation of enzymatic pathways leading to protein and nucleic acid cleavage and culminating in cell death. It is not clear whether NMD is required to ensure the accurate expression of apoptosis genes or is no longer necessary since cytotoxic proteins are not an issue during cell death. The present study shows that caspases cleave the two NMD factors UPF1 and UPF2 during apoptosis impairing NMD. Our results demonstrate a new regulatory pathway for NMD that occurs during apoptosis and provide evidence for role of the UPF cleaved fragments in apoptosis and NMD inhibition.
| S-EPMC4648321 | biostudies-literature
Project description:Caspases are intracellular proteases that propagate programmed cell death, proliferation, and inflammation. Activation of caspases occurs by a conserved mechanism subject to strict cellular regulation. Once activated by a specific stimulus, caspases execute limited proteolysis of downstream substrates to trigger a cascade of events that culminates in the desired biological response. Much has been learned of the mechanisms that govern the activation and regulation of caspases, and this minireview provides an update of these areas. We also delineate substantial gaps in knowledge of caspase function, which can be approached by techniques and experimental paradigms that are currently undergoing development.
| S-EPMC2755903 | biostudies-other
Project description:Dual-specificity mitogen-activated protein kinases kinases (MAPKKs) are the immediate upstream activators of MAPKs. They simultaneously phosphorylate the TXY motif within the activation loop of MAPKs, allowing them to interact with and regulate multiple substrates. Often, the activation of MAPKs triggers their nuclear translocation. However, the spatiotemporal dynamics and the physiological consequences of the activation of MAPKs, particularly in plants, are still poorly understood. Here, we studied the activation and localization of the Medicago sativa stress-induced MAPKK (SIMKK)-SIMK module after salt stress. In the inactive state, SIMKK and SIMK co-localized in the cytoplasm and in the nucleus. Upon salt stress, however, a substantial part of the nuclear pool of both SIMKK and SIMK relocated to cytoplasmic compartments. The course of nucleocytoplasmic shuttling of SIMK correlated temporally with the dual phosphorylation of the pTEpY motif. SIMKK function was further studied in Arabidopsis plants overexpressing SIMKK-yellow fluorescent protein (YFP) fusions. SIMKK-YFP plants showed enhanced activation of Arabidopsis MPK3 and MPK6 kinases upon salt treatment and exhibited high sensitivity against salt stress at the seedling stage, although they were salt insensitive during seed germination. Proteomic analysis of SIMKK-YFP overexpressors indicated the differential regulation of proteins directly or indirectly involved in salt stress responses. These proteins included catalase, peroxiredoxin, glutathione S-transferase, nucleoside diphosphate kinase 1, endoplasmic reticulum luminal-binding protein 2, and finally plasma membrane aquaporins. In conclusion, Arabidopsis seedlings overexpressing SIMKK-YFP exhibited higher salt sensitivity consistent with their proteome composition and with the presumptive MPK3/MPK6 hijacking of the salt response pathway.
| S-EPMC4036504 | biostudies-literature
Project description:BACKGROUND:Apoptosis is fundamental in maintaining cell balance in multicellular organisms, and caspases play a crucial role in apoptosis pathways. It is reported that apoptosis plays an important role in tick salivary gland degeneration. Several different caspases have been found in ticks, but the interactions between them are currently unknown. Here, we report three new caspases, isolated from the salivary glands of the tick Rhipicephalus haemaphysaloides. METHODS:The full-length cDNA of the RhCaspases 7, 8 and 9 genes were obtained by transcriptome, and RhCaspases 7, 8 and 9 were expressed in E. coli; after protein purification and immunization in mice, specific polyclonal antibodies (PcAb) were created in response to the recombinant protein. Reverse-transcription quantitative PCR (RT-qPCR) and western blot were used to detect the existence of RhCaspases 7, 8 and 9 in ticks. TUNEL assays were used to determine the apoptosis level in salivary glands at different feeding times after gene silencing. The interaction between RhCaspases 7, 8 and 9 were identified by co-transfection assays. RESULTS:The transcription of apoptosis-related genes in R. haemaphysaloides salivary glands increased significantly after tick engorgement. Three caspase-like molecules containing conserved caspase domains were identified and named RhCaspases 7, 8 and 9. RhCaspase8 and RhCaspase9 contain a long pro-domain at their N-terminals. An RT-qPCR assay demonstrated that the transcription of these three caspase genes increased significantly during the engorged periods of the tick developmental stages (engorged larval, nymph, and adult female ticks). Transcriptional levels of RhCaspases 7, 8 and 9 in salivary glands increased more significantly than other tissues post-engorgement. RhCaspase9-RNAi treatment significantly inhibited tick feeding. In contrast, knockdown of RhCaspase7 and RhCaspase8 had no influence on tick feeding. Compared to the control group, apoptosis levels were significantly reduced after interfering with RhCaspase 7, 8 and 9 expressions. Co-transfection assays showed RhCaspase7 was cleaved by RhCaspases 8 and 9, demonstrating that RhCaspases 8 and 9 are initiator caspases and RhCaspase7 is an executioner caspase. CONCLUSIONS:To the best of our knowledge, this is the first study to identify initiator and executioner caspases in ticks, confirm the interaction among them, and associate caspase activation with tick salivary gland degeneration.
| S-EPMC7275347 | biostudies-literature
Project description:Rapidly proliferating cells, such as cancer cells, have adopted aerobic glycolysis rather than oxidative phosphorylation to supply their energy demand; this phenomenon is known as 'the Warburg effect'. It is now widely accepted that during apoptosis the loss of energy production, orchestrated by caspases, contributes to the dismantling of the dying cell. However, how this loss of energy production occurs is still only partially known. In the present work, we established that during apoptosis the level of cellular ATP decreased in a caspase-dependent manner. We demonstrated that this decrease in ATP content was independent of any caspase modification of glucose uptake, ATP consumption or reactive oxygen species production but was dependent on a caspase-dependent inhibition of glycolysis. We found that the activity of the two glycolysis-limiting enzymes, phosphofructokinase and pyruvate kinase, were affected by caspases, whereas the activity of phosphoglycerate kinase was not, suggesting specificity of the effect. Finally, using a metabolomic analysis, we observed that caspases led to a decrease in several key metabolites, including phosphoserine, which is a major regulator of pyruvate kinase muscle isozyme activity. Thus, we have established that during apoptosis, caspases can shut down the main energy production pathway in cancer cells, leading to the impairment in the activity of the two enzymes controlling limiting steps of glycolysis.
| S-EPMC4540195 | biostudies-literature
Project description:In leukemia cells, hyperthermia enhances tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. The phenomenon is caspase-dependent and results in membrane changes leading to an increased recognition of TRAIL death receptors by TRAIL. Because either caspase-2 or an apical proteolytic event has been recently proposed to act as an initiator of the cell death mechanism induced by heat shock, we have investigated the hierarchy of caspase activation in cells exposed to the combined heat shock plus TRAIL treatment. We report here that caspases-2, -3, and -8 were the first caspases to be activated. As expected, caspase-8 is required and indispensable during the initiation of this death signaling. Caspase-2 may also participate in the phenomenon but, in contrast to caspase-8, its presence appears dispensable because its depletion by small interfering RNA is devoid of effects. Our observations also suggest a role of caspase-3 and of a particular cleaved form of this caspase during the early signals of heat shock plus TRAIL-induced apoptosis.
| S-EPMC2673937 | biostudies-other
Project description:p63 is a p53-related transcription factor. Utilization of two different promoters and alternative splicing at the C terminus lead to generation of six isoforms. The alpha isoforms of TAp63 and DeltaNp63 contain a transactivation-inhibitory (TI) domain at the C termini, which can bind to the transactivation (TA) domain and inhibit its transcriptional activity. Consequently, TAp63alpha can directly inhibit its activity through an intramolecular interaction; similarly, DeltaNp63alpha can inhibit the activity of the active TAp63 isoforms through an intermolecular interaction. In this work, we demonstrate that after induction of apoptosis, the TI domain of the p63alpha isoforms is cleaved by activated caspases. Cleavage of DeltaNp63alpha relieves its inhibitory effect on the transcriptionally active p63 proteins, and the cleavage of TAp63alpha results in production of a TAp63 protein with enhanced transcriptional activity. In agreement with these data, generation of the N-terminal TAp63 fragment has a role in apoptosis because stable cell lines expressing wild-type TAp63 are more sensitive to apoptosis compared with cells expressing the noncleavable mutant. We also used a model system in which TAp63 expression was induced by trichostatin-A treatment in HCT116 cells. Trichostatin-A sensitized these cells to apoptosis, and this sensitization was associated with cleavage of up-regulated p63.
| S-EPMC1904122 | biostudies-literature
Project description:The Dot/Icm system of Legionella pneumophila triggers activation of caspase-3 during early stages of infection of human macrophages, but apoptosis is delayed until late stages of infection. During early stages of infection of mouse macrophages, the organism triggers rapid caspase-1-mediated cytotoxicity, which is mediated by bacterial flagellin. However, it is not known whether caspase-1 is triggered by L. pneumophila in human macrophages or whether caspase-3 is activated in permissive or nonpermissive mouse macrophages. Using single-cell analyses, we show that the wild-type strain of L. pneumophila does not trigger caspase-1 activation throughout the intracellular infection of human monocyte-derived macrophages (hMDMs), even when the flagellated bacteria escape into the cytoplasm during late stages. Using single-cell analyses, we show that the Dot/Icm system of L. pneumophila triggers caspase-3 but not caspase-1 within permissive A/J mouse bone marrow-derived primary macrophages by 2 to 8 h, but apoptosis is delayed until late stages of infection. While L. pneumophila triggers a Dot/Icm-dependent activation of caspase-1 in nonpermissive BALB/c mouse-derived macrophages, caspase-3 is not activated at any stage of infection. We show that robust intrapulmonary replication of the wild-type strain of L. pneumophila in susceptible A/J mice is associated with late-stage Dot/Icm-dependent pulmonary apoptosis and alveolar inflammation. In the lungs of nonpermissive BALB/c mice, L. pneumophila does not replicate and does not trigger pulmonary apoptosis or alveolar inflammation. Thus, similar to hMDMs, L. pneumophila does not trigger caspase-1 but triggers caspase-3 activation during early and exponential replication in permissive A/J mouse-derived macrophages, and apoptosis is delayed until late stages of infection. The Dot/Icm type IV secretion system is essential for pulmonary apoptosis in the genetically susceptible A/J mice.
| S-EPMC1932860 | biostudies-other