scholarly journals The lysosomal Rag-Ragulator complex licenses RIPK1– and caspase-8–mediated pyroptosis by Yersinia

Science ◽  
2021 ◽  
Vol 372 (6549) ◽  
pp. eabg0269
Author(s):  
Zengzhang Zheng ◽  
Wanyan Deng ◽  
Yang Bai ◽  
Rui Miao ◽  
Shenglin Mei ◽  
...  
Keyword(s):  
Cell Death ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Host Cells ◽  
Caspase 8 ◽  
Death Domain ◽  
Interacting Protein ◽  
A Genome ◽  
Infection Inhibition ◽  
Guanosine Triphosphatase

Host cells initiate cell death programs to limit pathogen infection. Inhibition of transforming growth factor–β–activated kinase 1 (TAK1) by pathogenic Yersinia in macrophages triggers receptor-interacting serine-threonine protein kinase 1 (RIPK1)–dependent caspase-8 cleavage of gasdermin D (GSDMD) and inflammatory cell death (pyroptosis). A genome-wide CRISPR screen to uncover mediators of caspase-8–dependent pyroptosis identified an unexpected role of the lysosomal folliculin (FLCN)–folliculin-interacting protein 2 (FNIP2)–Rag-Ragulator supercomplex, which regulates metabolic signaling and the mechanistic target of rapamycin complex 1 (mTORC1). In response to Yersinia infection, Fas-associated death domain (FADD), RIPK1, and caspase-8 were recruited to Rag-Ragulator, causing RIPK1 phosphorylation and caspase-8 activation. Pyroptosis activation depended on Rag guanosine triphosphatase activity and lysosomal tethering of Rag-Ragulator but not mTORC1. Thus, the lysosomal metabolic regulator Rag-Ragulator instructs the inflammatory response to Yersinia.

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 The E3 Ubiquitin-Protein Ligase RNF4 Promotes TNF-α-Induced Cell Death Triggered by RIPK1

2021 ◽  
Vol 22 (11) ◽  
pp. 5796
Author(s):  
Tatsuya Shimada ◽  
Yuki Kudoh ◽  
Takuya Noguchi ◽  
Tomohiro Kagi ◽  
Midori Suzuki ◽  
...  
Keyword(s):  
Cell Death ◽  
Posttranslational Modifications ◽  
Transforming Growth Factor ◽  
Ring Finger ◽  
Transforming Growth Factor Β ◽  
Nuclear Factor Κb ◽  
Interacting Protein ◽  
Signaling Complex ◽  
Enhanced Sensitivity ◽  
Tnf Α

Receptor-interacting protein kinase 1 (RIPK1) is a key component of the tumor necrosis factor (TNF) receptor signaling complex that regulates both pro- and anti-apoptotic signaling. The reciprocal functions of RIPK1 in TNF signaling are determined by the state of the posttranslational modifications (PTMs) of RIPK1. However, the underlying mechanisms associated with the PTMs of RIPK1 are unclear. In this study, we found that RING finger protein 4 (RNF4), a RING finger E3 ubiquitin ligase, is required for the RIPK1 autophosphorylation and subsequent cell death. It has been reported that RNF4 negatively regulates TNF-α-induced activation of the nuclear factor-κB (NF-κB) through downregulation of transforming growth factor β-activated kinase 1 (TAK1) activity, indicating the possibility that RNF4-mediated TAK1 suppression results in enhanced sensitivity to cell death. However, interestingly, RNF4 was needed to induce RIPK1-mediated cell death even in the absence of TAK1, suggesting that RNF4 can promote RIPK1-mediated cell death without suppressing the TAK1 activity. Thus, these observations reveal the existence of a novel mechanism whereby RNF4 promotes the autophosphorylation of RIPK1, which provides a novel insight into the molecular basis for the PTMs of RIPK1.

scholarly journals TAK1 Is Essential for Osteoclast Differentiation and Is an Important Modulator of Cell Death by Apoptosis and Necroptosis

2012 ◽  
Vol 33 (3) ◽  
pp. 582-595 ◽  
Author(s):  
Betty Lamothe ◽  
YunJu Lai ◽  
Min Xie ◽  
Michael D. Schneider ◽  
Bryant G. Darnay
Keyword(s):  
Cell Death ◽  
Transforming Growth Factor ◽  
Interleukin 1 ◽  
Osteoclast Differentiation ◽  
Transforming Growth Factor Β ◽  
Nuclear Factor Κb ◽  
Interacting Protein ◽  
Iκb Kinase ◽  
Mitogen Activated Protein ◽  
Macrophage Colony

ABSTRACTTransforming growth factor β (TGF-β)-activated kinase 1 (TAK1), a mitogen-activated protein 3 (MAP3) kinase, plays an essential role in inflammation by activating the IκB kinase (IKK)/nuclear factor κB (NF-κB) and stress kinase (p38 and c-Jun N-terminal kinase [JNK]) pathways in response to many stimuli. The tumor necrosis factor (TNF) superfamily member receptor activator of NF-κB ligand (RANKL) regulates osteoclastogenesis through its receptor, RANK, and the signaling adaptor TRAF6. Because TAK1 activation is mediated through TRAF6 in the interleukin 1 receptor (IL-1R) and toll-like receptor (TLR) pathways, we sought to investigate the consequence of TAK1 deletion in RANKL-mediated osteoclastogenesis. We generated macrophage colony-stimulating factor (M-CSF)-derived monocytes from the bone marrow of mice with TAK1 deletion in the myeloid lineage. Unexpectedly, TAK1-deficient monocytes in culture died rapidly but could be rescued by retroviral expression of TAK1, inhibition of receptor-interacting protein 1 (RIP1) kinase activity with necrostatin-1, or simultaneous genetic deletion of TNF receptor 1 (TNFR1). Further investigation using TAK1-deficient mouse embryonic fibroblasts revealed that TNF-α-induced cell death was abrogated by the simultaneous inhibition of caspases and knockdown of RIP3, suggesting that TAK1 is an important modulator of both apoptosis and necroptosis. Moreover, TAK1-deficient monocytes rescued from programmed cell death did not form mature osteoclasts in response to RANKL, indicating that TAK1 is indispensable to RANKL-induced osteoclastogenesis. To our knowledge, we are the first to report that mice in which TAK1 has been conditionally deleted in osteoclasts develop osteopetrosis.

scholarly journals Death Receptor-Induced Activation of Initiator Caspase 8 Is Antagonized by Serine/Threonine Kinase PAK4

2003 ◽  
Vol 23 (21) ◽  
pp. 7838-7848 ◽  
Author(s):  
Nerina Gnesutta ◽  
Audrey Minden
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Intracellular Signaling ◽  
Death Receptor ◽  
Caspase 8 ◽  
Death Domain ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Different Types ◽  
Promote Cell Survival

ABSTRACT Normal cell growth requires a precisely controlled balance between cell death and survival. This involves activation of different types of intracellular signaling cascades within the cell. While some types of signaling proteins regulate apoptosis, or programmed cell death, other proteins within the cell can promote survival. The serine/threonine kinase PAK4 can protect cells from apoptosis in response to several different types of stimuli. As is the case for other members of the p21-activated kinase (PAK) family, one way that PAK4 may promote cell survival is by phosphorylating and thereby inhibiting the proapoptotic protein Bad. This leads in turn to the inhibition of effector caspases such as caspase 3. Here we show that in response to cytokines which activate death domain-containing receptors, such as the tumor necrosis factor and Fas receptors, PAK4 can inhibit the death signal by a different mechanism. Under these conditions, PAK4 inhibits apoptosis early in the caspase cascade, antagonizing the activation of initiator caspase 8. This inhibition, which does not require PAK4's kinase activity, may involve inhibition of caspase 8 recruitment to the death domain receptors. This role in regulating initiator caspases is an entirely novel role for the PAK proteins and suggests a new mechanism by which these proteins promote cell survival.

scholarly journals p38-mediated Regulation of an Fas-associated Death Domain Protein-independent Pathway Leading to Caspase-8 Activation during TGFβ-induced Apoptosis in Human Burkitt Lymphoma B Cells BL41

2001 ◽  
Vol 12 (10) ◽  
pp. 3139-3151 ◽  
Author(s):  
Nicolas Schrantz ◽  
Marie-Françoise Bourgeade ◽  
Shahul Mouhamad ◽  
Gérald Leca ◽  
Surendra Sharma ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Transforming Growth Factor ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Caspase 8 ◽  
Death Domain ◽  
Apoptotic Pathway ◽  
Domain Protein

On binding to its receptor, transforming growth factor β (TGFβ) induces apoptosis in a variety of cells, including human B lymphocytes. We have previously reported that TGFβ-mediated apoptosis is caspase-dependent and associated with activation of caspase-3. We show here that caspase-8 inhibitors strongly decrease TGFβ-mediated apoptosis in BL41 Burkitt's lymphoma cells. These inhibitors act upstream of the mitochondria because they inhibited the loss of mitochondrial membrane potential observed in TGFβ-treated cells. TGFβ induced caspase-8 activation in these cells as shown by the cleavage of specific substrates, including Bid, and the appearance of cleaved fragments of caspase-8. Our data show that TGFβ induces an apoptotic pathway involving sequential caspase-8 activation, loss of mitochondrial membrane potential, and caspase-9 and -3 activation. Caspase-8 activation was Fas-associated death domain protein (FADD)-independent because cells expressing a dominant negative mutant of FADD were still sensitive to TGFβ-induced caspase-8 activation and apoptosis. This FADD-independent pathway of caspase-8 activation is regulated by p38. Indeed, TGFβ-induced activation of p38 and two different inhibitors specific for this mitogen-activated protein kinase pathway (SB203580 and PD169316) prevented TGFβ-mediated caspase-8 activation as well as the loss of mitochondrial membrane potential and apoptosis. Overall, our data show that p38 activation by TGFβ induced an apoptotic pathway via FADD-independent activation of caspase-8.

scholarly journals The Activity of Differentiation Factors Induces Apoptosis in Polyomavirus Large T-Expressing Myoblasts

1998 ◽  
Vol 9 (6) ◽  
pp. 1449-1463 ◽  
Author(s):  
Gian Maria Fimia ◽  
Vanesa Gottifredi ◽  
Barbara Bellei ◽  
Maria Rosaria Ricciardi ◽  
Agostino Tafuri ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Growth Factor ◽  
Cell Cycle Progression ◽  
Transforming Growth Factor ◽  
Myogenic Differentiation ◽  
Transforming Growth Factor Β ◽  
Large Tumor ◽  
Cycle Progression

It is commonly accepted that pathways that regulate proliferation/differentiation processes, if altered in their normal interplay, can lead to the induction of programmed cell death. In a previous work we reported that Polyoma virus Large Tumor antigen (PyLT) interferes with in vitro terminal differentiation of skeletal myoblasts by binding and inactivating the retinoblastoma antioncogene product. This inhibition occurs after the activation of some early steps of the myogenic program. In the present work we report that myoblasts expressing wild-type PyLT, when subjected to differentiation stimuli, undergo cell death and that this cell death can be defined as apoptosis. Apoptosis in PyLT-expressing myoblasts starts after growth factors removal, is promoted by cell confluence, and is temporally correlated with the expression of early markers of myogenic differentiation. The block of the initial events of myogenesis by transforming growth factor β or basic fibroblast growth factor prevents PyLT-induced apoptosis, while the acceleration of this process by the overexpression of the muscle-regulatory factor MyoD further increases cell death in this system. MyoD can induce PyLT-expressing myoblasts to accumulate RB, p21, and muscle- specific genes but is unable to induce G00arrest. Several markers of different phases of the cell cycle, such as cyclin A, cdk-2, and cdc-2, fail to be down-regulated, indicating the occurrence of cell cycle progression. It has been frequently suggested that apoptosis can result from an unbalanced cell cycle progression in the presence of a contrasting signal, such as growth factor deprivation. Our data involve differentiation pathways, as a further contrasting signal, in the generation of this conflict during myoblast cell apoptosis.

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.

Genetic Regulation of RIPK1 and Necroptosis

2021 ◽  
Vol 55 (1) ◽  
pp. 235-263
Author(s):  
Daichao Xu ◽  
Chengyu Zou ◽  
Junying Yuan
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Genetic Regulation ◽  
Caspase 8 ◽  
Inflammatory Signaling ◽  
Interacting Protein ◽  
Multiple Factors ◽  
Cell Death Pathways ◽  
Upstream Regulator ◽  
Multiple Cell

The receptor-interacting protein kinase 1 (RIPK1) is recognized as a master upstream regulator that controls cell survival and inflammatory signaling as well as multiple cell death pathways, including apoptosis and necroptosis. The activation of RIPK1 kinase is extensively modulated by ubiquitination and phosphorylation, which are mediated by multiple factors that also control the activation of the NF-κB pathway. We discuss current findings regarding the genetic modulation of RIPK1 that controls its activation and interaction with downstream mediators, such as caspase-8 and RIPK3, to promote apoptosis and necroptosis. We also address genetic autoinflammatory human conditions that involve abnormal activation of RIPK1. Leveraging these new genetic and mechanistic insights, we postulate how an improved understanding of RIPK1 biology may support the development of therapeutics that target RIPK1 for the treatment of human inflammatory and neurodegenerative diseases.

Interaction with Sug1 enables Ipaf ubiquitination leading to caspase 8 activation and cell death

2010 ◽  
Vol 427 (1) ◽  
pp. 91-104 ◽  
Author(s):  
Yatender Kumar ◽  
Vegesna Radha ◽  
Ghanshyam Swarup
Keyword(s):  
Cell Death ◽  
Mammalian Cells ◽  
Intramolecular Interaction ◽  
Dominant Negative ◽  
26S Proteasome ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Caspase 1 ◽  
Lung Carcinoma Cells ◽  
Lrr Domain

Activation of initiator caspases is dependent on interacting proteins, and Ipaf [ICE (interleukin-1β-converting enzyme)-protease activating factor] {NLRC4 [NLR (Nod-like receptor) family CARD (caspase activation and recruitment domain)-containing 4]} an inflammasome component, is involved in caspase 1 activation and apoptosis. Investigating the mechanisms of Ipaf activation, we found that the C-terminal LRR (leucine-rich repeat) domain of Ipaf, through intramolecular interaction, negatively regulates its apoptosis-inducing function. In A549 lung carcinoma cells, expression of Ac-Ipaf (LRR-domain-deleted Ipaf) induced cell death that was dependent on caspase 8, but not on caspase 1. A yeast two-hybrid screen using Ac-Ipaf as bait identified human Sug1 (suppressor of gal 1), a component of the 26S proteasome, as an interacting protein. In mammalian cells Sug1 interacts and co-localizes with Ipaf. Sug1 binds to amino acids 91–253 of Ipaf, which is also the region that the LRR domain binds to. It potentiates cell death induced by Ipaf and Ac-Ipaf, and co-expression of Sug1 and Ipaf induces caspase-8-dependent cell death. Cellular complexes formed by Ipaf and Sug1 contain caspase 8. Expression of Ac-Ipaf or co-expression of Sug1 with Ipaf results in the formation of cytoplasmic aggregates and caspase 8 activation. Sug1 co-expression enabled modification of Ipaf by ubiquitination. Tagging ubiquitin molecules to Ipaf led to aggregate formation, enhanced caspase 8 interaction and activation, resulting in induction of cell death. Using RNAi (RNA interference) and dominant-negative approaches, we have shown that cell death induced by Ac-Ipaf expression or by treatment with TNF-α (tumour necrosis factor α) or doxorubicin is dependent on Sug1. Our results suggest a role for ubiquitination of Ipaf that is enabled by its interaction with Sug1, leading to caspase 8 activation and cell death.

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