An immunohistochemical atlas of necroptotic pathway expression
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE262762 | GEO | 2024/04/17
REPOSITORIES: GEO
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Project description:Necroptosis is a caspase-independent, pro-inflammatory mode of programmed cell death which relies on the activation of the terminal effector, MLKL, by the upstream protein kinase RIPK3. To mediate necroptosis, RIPK3 must stably interact with, and phosphorylate the pseudokinase domain of MLKL. While the precise molecular cue that prompts RIPK3 to activate MLKL is incompletely understood, it is known that RIPK3 is highly regulated by phosphorylation. Here, we sought to identify phosphorylation sites of RIPK3 and dissect their regulatory functions. Phosphoproteomics identified 21 phosphorylation sites in HT29 cells overexpressing human RIPK3. By comparing cells expressing wild-type and kinase-inactive D142N RIPK3, autophosphorylation sites and substrates of other cellular kinases were distinguished. Of these 21 phosphosites, extensive mutational analyses identified only pT224 and pS227 as crucial, synergistic sites for stable interaction with MLKL to promote necroptosis, while the recently reported activation loop phosphorylation at S164/T165 negatively regulate the kinase activity of RIPK3. Despite being able to phosphorylate MLKL to a similar or higher extent than the wild-type RIPK3, mutation of T224, S227, and RHIM in RIPK3 attenuated or compromised their abilities to mediate necroptosis. This finding highlights the stable recruitment of human MLKL by RIPK3 to the necrosome as an essential checkpoint in necroptosis signaling, which is independent from and precedes the phosphorylation of MLKL.
2022-07-30 | PXD033488 | Pride
Project description:The activation of Mixed Lineage Kinase-Like (MLKL) by Receptor Interacting Protein Kinase-3 (RIPK3) results in plasma membrane (PM) disruption and a form of regulated necrosis, called necroptosis. Here we show that during necroptosis, MLKL-dependent calcium (Ca++) influx and phosphatidylserine (PS) exposure on the outer leaflet of the plasma membrane preceded loss of PM integrity. Activation of MLKL results in the generation of broken, PM “bubbles” with exposed PS that are released from the surface of the otherwise intact cell. Components of the ESCRT machinery are required for formation of these bubbles, and act to sustain survival of the cell when MLKL activation is limited or reversed. Under conditions of necroptotic cell death, ESCRT controls the duration of plasma membrane integrity. As a consequence of the action of ESCRT, cells undergoing necroptosis can express chemokines and other regulatory molecules, and promote antigenic cross-priming of CD8+ T cells.
2017-06-16 | GSE85660 | GEO
Project description:Necroptosis is a lytic and inflammatory form of cell death that is highly constrained to mitigate detrimental collateral tissue damage and impaired immunity. These constraints make it difficult to define the relevance of necroptosis in diseases such as chronic and persistent viral infections and within individual organ systems. The role of necroptotic signalling is further complicated because proteins essential to this pathway, such as receptor interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL), have been implicated in roles outside of necroptotic signalling. We sought to address this issue by individually defining the role of RIPK3 and MLKL in chronic lymphocytic choriomeningitis virus (LCMV) infection. We investigated if necroptosis contributes to the death of LCMV-specific CD8+ T cells or virally infected target cells during infection. We provide evidence showing that necroptosis was redundant in the pathogenesis of acute forms of LCMV (Armstrong strain) and the early stages of chronic (Docile strain) LCMV infection in vivo. The number of immune cells, their specificity and reactivity towards viral antigens and viral loads are not altered in the absence of either MLKL or RIPK3 during acute and during the early stages of chronic LCMV infection. However, we identified that RIPK3 promotes immune dysfunction and prevents control of infection at later stages of chronic LCMV disease. This was not phenocopied by the loss of MLKL indicating that the phenotype was driven by a necroptosis-independent function of RIPK3. We provide evidence that RIPK3 signaling evoked a dysregulated type 1 interferone response which we linked to an impaired antiviral immune response and abrogated clearance of chronic LCMV infection.
2023-03-12 | GSE224066 | GEO
Project description:Necroptosis is a form of programmed cell death that is defined by activation of the kinase RIPK3, and subsequent cell membrane permeabilization by the effector MLKL. In addition to triggering cell death, RIPK3 activation can promote immune responses through the production of cytokines and chemokines. How active cytokine production is coordinated with the terminal process of necroptosis is unclear. Here, we report that cytokine production continues within necroptotic cells after cells have lost plasma membrane integrity and irreversibly commited to death. The continued production of inflammatory mediators was dependent on mRNA translation, and required maintanence of endoplasmic reticulum integrity, which remained in tact after plasma membrane integrity was lost. The continued translation of cytokines by cellular corpses contributed to necroptotic cell uptake by innate immune cells, as well as priming of adaptive immune responses to antigens associated with necroptotic corpses. These findings imply that necroptosis may represent a program in which cell death and production of inflammatory mediators are coordinated to optimize the immunogenicity of necroptotic cells.
2019-07-13 | GSE134234 | GEO
Project description:Necroptosis is a regulated but inflammatory form of cell death. We and others have previously reported that necroptotic cells release extracellular vesicles (EVs). We found that necroptotic EVs are loaded with proteins, including the key necroptosis executor factor, phosphorylated mixed lineage kinase domain-like (pMLKL). However, the exact necroptotic EVs proteins composition and impact have not been delineated yet. To characterize their content, EVs from necroptotic and untreated U937 cells were isolated by ultracentrifugation and analyzed by mass spectrometry. A total of 3337 proteins were identified, sharing high similarity with exosome proteome databases. Unsupervised hierarchical clustering of identified proteins distinguished between necroptotic and control EVs. A total of 353 proteins was significantly upregulated in the necroptotic EVs. Among these are MLKL and caspase-8, as validated by immunoblot. Components of ESCRTIII machinery and inflammatory signaling were found to be enriched in the necroptotic EVs, as well as yet unreported components of vesicles formation and transport and necroptosis signaling pathways. Moreover, we show that necroptotic EVs can be phagocytosed by macrophages to modulate cytokine and chemokine secretion. Finally, we reveal that necroptotic EVs contain tumor neoantigen and are enriched with proteins annotated as “antigen processing and presentation” biological process. In summary, our study reveals a new layer of regulation during the early stage of necroptosis by the secretion of specific EVs that influence their microenvironment and may instigate innate and adaptive immune responses. Future investigation will shed light on new players in the necroptosis signaling and its related EVs, and will uncover the functional tasks accomplished by the cargo of these necroptotic EVs.
2021-11-11 | PXD018258 | Pride
Project description:Mixed lineage kinase domain-like (MLKL) is the executioner in the caspase 8-independent form of programmed cell death called necroptosis. Once Receptor Interacting serine/threonine Protein Kinase 3 (RIPK3) is activated by upstream cell death signals, it phosphorylates MLKL and triggers the oligomerization and membrane translocation required for MLKL induced membrane disruption. Besides phosphorylation, MLKL also undergoes ubiquitylation during the early stages of necroptosis, yet neither the mechanism nor the significance of this event has been demonstrated. Here we show that necroptosis-specific, multi-mono-ubiquitylation of MLKL occurs on biological membranes, and requires its activation and oligomerisation. Inactive MLKL mutants recruited to membranes during necroptosis are ubiquitylated but this results in their proteasome and lysosome dependent turnover. We identified several ubiquitylated lysines however mutation of these did not affect MLKL ubiquitylation in response to a necroptotic stimulus.
2021-04-28 | PXD015537 | Pride
Project description:Caspase-8 and FADD play key roles in the regulation of cell death by necroptosis. The absence of either protein results in early embryonic lethality due to the activation of the kinase RIPK3 and its phosphorylation of the necroptosis executioner, MLKL. We genetically engineered and characterized a mouse model to monitor MLKL phosphorylation in the absence of necroptosis in vivo. Ablation of caspase-8 or FADD resulted in the transcriptional upregulation in several tissues of ZBP1, a cytosolic nucleic acid sensor capable of activating RIPK3, and ZBP1 was required for spontaneous phosphorylation of MLKL. Our findings provide a novel mechanism by which the FADD-Caspase-8 complex prevents necroptosis.
2022-09-19 | GSE208744 | GEO
Project description:Diquat (DQ) poisoning is a severe medical condition with life-threatening implications and multi-organ dysfunction, yet its underlying mechanism remains incompletely understood. This study unveils a critical process in DQ-induced toxicity. DQ disrupts the mitochondrial genome stability in endothelial cells, leading to the accumulation of Z-form DNA. This triggers an interaction between Z-DNA binding protein 1 (ZBP1) and receptor interacting protein kinase 3 (RIPK3), setting off RIPK3-dependent necroptotic and ferroptotic signaling pathways. Depletion of ZBP1 or RIPK3 in endothelial cells effectively inhibits both necroptosis and ferroptosis, reducing organ damage and mortality. Importantly, we discover that RIPK3 plays a dual role. It phosphorylates MLKL to induce necroptosis and phosphorylates FSP1, inhibiting its enzymatic activity and promoting ferroptosis. The phosphorylation of T163 in FSP1 is crucial for suppressing its activity. Combining the deletion of MLKL with vitamin K treatment proves highly effective in mitigating multi-organ damage and lethality caused by DQ.
2024-03-25 | GSE244858 | GEO
Project description:Extracellular vesicles (EVs) are important mechanisms used by cells to release biomolecules. A common necroptosis effector— mixed lineage kinase like (MLKL)--- was recently found to participate in the biogenesis of small and large EVs independent of its function in necroptosis. The objective of the current study is to gain mechanistic insights into EV biogenesis during necroptosis. We performed mass spectrometry-based proteomics on EVs released by healthy or necroptotic cells. Necroptosis increased the number of EVs released and altered the protein contents within the EVs. Comparing to EVs released by healthy cells, EVs released during necroptosis contained markedly higher number of unique proteins. Receptor interacting protein kinase 3 (RIPK3) and MLKL were among the proteins enriched in EVs released during necroptosis. Further, MEFs derived from mice deficient of Rab27a and Rab27b showed diminished basal EV release but responded to necroptosis with enhanced EV biogenesis as the wildtype MEFs. In contrast, necroptosis-associated EVs was sensitive to Ca2+ depletion or lysosomal disruption. Neither treatments affected the RIPK3-mediated MLKL phosphorylation. Our data suggests that necroptosis switches EV biogenesis from a Rab27a/b dependent mechanism to a lysosomal mediated mechanism.
2022-08-14 | PXD031224 | Pride
Project description:Necroptosis is a lytic form of cell death that is mediated by the kinase RIPK3 and the pseudokinase MLKL when caspase-8 is inhibited downstream of death receptors, toll-like receptor 3 (TLR3), TLR4, and the intracellular Z-form nucleic acid sensor ZBP1. Oligomerization and activation of RIPK3 is driven by interactions with the kinase RIPK1, the TLR adaptor TRIF, or ZBP1. In this study, we use immunohistochemistry (IHC) and in situ hybridization (ISH) assays to generate a tissue atlas characterizing RIPK1, RIPK3, Mlkl, and ZBP1 expression in mouse tissues. RIPK1, RIPK3, and Mlkl were co-expressed in most immune cell populations, endothelial cells, and many mucosal epithelia. ZBP1 was expressed in many immune populations, but had more variable expression in epithelia compared to RIPK1, RIPK3, and Mlkl. Intriguingly, expression of ZBP1 was elevated in Casp8-/- Tnfr1-/- embryos prior to their succumbing to aberrant necroptosis around embryonic day 15. ZBP1 contributed to this embryonic lethality because rare Casp8-/- Tnfr1-/- Zbp1-/- mice survived until after birth. Necroptosis mediated by TRIF contributed to the demise of Casp8-/- Tnfr1-/- Zbp1-/- pups in the perinatal period. Of note, Casp8-/- Tnfr1-/- Trif-/- Zbp1-/- mice exhibited autoinflammation and morbidity, typically within 5-7 weeks of being born, which is not seen in Casp8-/- Ripk1-/- Trif-/- Zbp1-/-, Casp8-/- Ripk3-/-, or Casp8-/- Mlkl-/- mice. Therefore, after birth, loss of caspase-8 probably unleashes RIPK1-dependent necroptosis driven by death receptors other than TNFR1.
2024-04-01 | GSE254754 | GEO