The Experts below are selected from a list of 4602 Experts worldwide ranked by ideXlab platform
Lorella M T Canzoniero - One of the best experts on this subject based on the ideXlab platform.
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the neurotoxicant pcb 95 by increasing the neuronal transcriptional repressor rest down regulates caspase 8 and increases ripk1 RIPK3 and mlkl expression determining necroptotic neuronal death
Biochemical Pharmacology, 2017Co-Authors: Natascia Guida, Giusy Laudati, Angelo Serani, Paolo Montuori, Luigi Mascolo, Lorella M T Canzoniero, Gianfranco Di Renzo, Pasquale MolinaroAbstract:Abstract Our previous study showed that the environmental neurotoxicant non-dioxin-like polychlorinated biphenyl (PCB)-95 increases RE1-silencing transcription factor (REST) expression, which is related to necrosis, but not apoptosis, of neurons. Meanwhile, necroptosis is a type of a programmed necrosis that is positively regulated by receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL) and negatively regulated by caspase-8. Here we evaluated whether necroptosis contributes to PCB-95-induced neuronal death through REST up-regulation. Our results demonstrated that in cortical neurons PCB-95 increased RIPK1, RIPK3, and MLKL expression and decreased caspase-8 at the gene and protein level. Furthermore, the RIPK1 inhibitor necrostatin-1 or siRNA-mediated RIPK1, RIPK3 and MLKL expression knockdown significantly reduced PCB-95-induced neuronal death. Intriguingly, PCB-95-induced increases in RIPK1, RIPK3, MLKL expression and decreases in caspase-8 expression were reversed by knockdown of REST expression with a REST-specific siRNA (siREST). Notably, in silico analysis of the rat genome identified a REST consensus sequence in the caspase-8 gene promoter (Casp8-RE1), but not the RIPK1, RIPK3 and MLKL promoters. Interestingly, in PCB-95-treated neurons, REST binding to the Casp8-RE1 sequence increased in parallel with a reduction in its promoter activity, whereas under the same experimental conditions, transfection of siREST or mutation of the Casp8-RE1 sequence blocked PCB-95-induced caspase-8 reduction. Since RIPK1, RIPK3 and MLKL rat genes showed no putative REST binding site, we assessed whether the transcription factor cAMP Responsive Element Binding Protein (CREB), which has a consensus sequence in all three genes, affected neuronal death. In neurons treated with PCB-95, CREB protein expression decreased in parallel with a reduction in binding to the RIPK1, RIPK3 and MLKL gene promoter sequence. Furthermore, CREB overexpression was associated with reduced promoter activity of the RIPK1, RIPK3 and MLKL genes. Collectively, these results indicate that PCB-95 was associated with REST-induced necroptotic cell death by increasing RIPK1, RIPK3 and MLKL expression and reducing caspase-8 levels. In addition, since REST is involved in several neurological disorders, therapies that block REST-induced necroptosis could be a new strategy to revert the neurodetrimental effects associated to its overexpression.
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the neurotoxicant pcb 95 by increasing the neuronal transcriptional repressor rest down regulates caspase 8 and increases ripk1 RIPK3 and mlkl expression determining necroptotic neuronal death
Biochemical Pharmacology, 2017Co-Authors: Natascia Guida, Giusy Laudati, Angelo Serani, Paolo Montuori, Luigi Mascolo, Lorella M T Canzoniero, Gianfranco Di Renzo, Pasquale MolinaroAbstract:Abstract Our previous study showed that the environmental neurotoxicant non-dioxin-like polychlorinated biphenyl (PCB)-95 increases RE1-silencing transcription factor (REST) expression, which is related to necrosis, but not apoptosis, of neurons. Meanwhile, necroptosis is a type of a programmed necrosis that is positively regulated by receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL) and negatively regulated by caspase-8. Here we evaluated whether necroptosis contributes to PCB-95-induced neuronal death through REST up-regulation. Our results demonstrated that in cortical neurons PCB-95 increased RIPK1, RIPK3, and MLKL expression and decreased caspase-8 at the gene and protein level. Furthermore, the RIPK1 inhibitor necrostatin-1 or siRNA-mediated RIPK1, RIPK3 and MLKL expression knockdown significantly reduced PCB-95-induced neuronal death. Intriguingly, PCB-95-induced increases in RIPK1, RIPK3, MLKL expression and decreases in caspase-8 expression were reversed by knockdown of REST expression with a REST-specific siRNA (siREST). Notably, in silico analysis of the rat genome identified a REST consensus sequence in the caspase-8 gene promoter (Casp8-RE1), but not the RIPK1, RIPK3 and MLKL promoters. Interestingly, in PCB-95-treated neurons, REST binding to the Casp8-RE1 sequence increased in parallel with a reduction in its promoter activity, whereas under the same experimental conditions, transfection of siREST or mutation of the Casp8-RE1 sequence blocked PCB-95-induced caspase-8 reduction. Since RIPK1, RIPK3 and MLKL rat genes showed no putative REST binding site, we assessed whether the transcription factor cAMP Responsive Element Binding Protein (CREB), which has a consensus sequence in all three genes, affected neuronal death. In neurons treated with PCB-95, CREB protein expression decreased in parallel with a reduction in binding to the RIPK1, RIPK3 and MLKL gene promoter sequence. Furthermore, CREB overexpression was associated with reduced promoter activity of the RIPK1, RIPK3 and MLKL genes. Collectively, these results indicate that PCB-95 was associated with REST-induced necroptotic cell death by increasing RIPK1, RIPK3 and MLKL expression and reducing caspase-8 levels. In addition, since REST is involved in several neurological disorders, therapies that block REST-induced necroptosis could be a new strategy to revert the neurodetrimental effects associated to its overexpression.
Kim Newton - One of the best experts on this subject based on the ideXlab platform.
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kinase domain dimerization drives RIPK3 dependent necroptosis
Science Signaling, 2018Co-Authors: Saravanan Raju, Kim Newton, Joshua D Webster, Daniel M Whalen, Meron Mengistu, Carter Swanson, John Quinn, Susan S Taylor, Andrey S ShawAbstract:Necroptosis, an inflammatory form of cell death, is initiated by the activation of receptor-interacting protein kinase 3 (RIPK3), which depends on its interaction with RIPK1. Although catalytically inactive, the RIPK3 mutant D161N still stimulates RIPK1-dependent apoptosis and embryonic lethality in RIPK3 D161N homozygous mice. Whereas the absence of RIPK1 rescues RIPK3 D161N homozygous mice, we report that the absence of RIPK1 leads to embryonic lethality in RIPK3 D161N heterozygous mice. This suggested that the kinase domain of RIPK3 had a noncatalytic function that was enhanced by a conformation induced by the D161N mutation. We found that the RIPK3 kinase domain homodimerized through a surface that is structurally similar to that of the RAF family members. Mutation of residues at the dimer interface impaired dimerization and necroptosis. Kinase domain dimerization stimulated the activation of RIPK3 through cis-autophosphorylation. This noncatalytic, allosteric activity was enhanced by certain kinase-deficient mutants of RIPK3, including D161N. Furthermore, apoptosis induced by certain RIPK3 inhibitors was also dependent on the kinase dimerization interface. Our studies reveal that the RIPK3 kinase domain exhibits catalytically independent function that is important for both RIPK3-dependent necroptosis and apoptosis.
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ripk1 inhibits zbp1 driven necroptosis during development
Nature, 2016Co-Authors: Kim Newton, Merone Roosegirma, Victoria C Pham, Debra L. Dugger, Katherine E. Wickliffe, Allie Maltzman, Jennie R Lill, Andreas Strasser, Soren WarmingAbstract:In the absence of RIPK1, ZBP1 engages RIPK3 in a RHIM-dependent manner and acts as a critical activator of RIPK3/MLKL-dependent necroptosis. Receptor-interacting protein kinase 1 (RIPK1) is known to act as a brake on apoptosis and necroptosis during development. Here Kim Newton et al. report that, in the absence of RIPK1, the adapter protein ZBP1 (also known as DAI) engages RIPK3 in a RIP homotypic interaction motif (RHIM)-dependent manner and acts as a critical activator of RIPK3–MLKL-dependent necroptosis. This finding, together with related analyses, suggests an unexpected role for ZBP1 in triggering necroptosis in the perinatal period. Receptor-interacting protein kinase 1 (RIPK1) promotes cell survival—mice lacking RIPK1 die perinatally, exhibiting aberrant caspase-8-dependent apoptosis and mixed lineage kinase-like (MLKL)-dependent necroptosis1,2,3. However, mice expressing catalytically inactive RIPK1 are viable2,4,5, and an ill-defined pro-survival function for the RIPK1 scaffold has therefore been proposed. Here we show that the RIP homotypic interaction motif (RHIM) in RIPK1 prevents the RHIM-containing adaptor protein ZBP1 (Z-DNA binding protein 1; also known as DAI or DLM1) from activating RIPK3 upstream of MLKL. Ripk1RHIM/RHIM mice that expressed mutant RIPK1 with critical RHIM residues IQIG mutated to AAAA died around birth and exhibited RIPK3 autophosphorylation on Thr231 and Ser232, which is a hallmark of necroptosis6, in the skin and thymus. Blocking necroptosis with catalytically inactive RIPK3(D161N), RHIM mutant RIPK3, RIPK3 deficiency, or MLKL deficiency prevented lethality in Ripk1RHIM/RHIM mice. Loss of ZBP1, which engages RIPK3 in response to certain viruses7,8 but previously had no defined role in development, also prevented perinatal lethality in Ripk1RHIM/RHIM mice. Consistent with the RHIM of RIPK1 functioning as a brake that prevents ZBP1 from engaging the RIPK3 RHIM, ZBP1 interacted with RIPK3 in Ripk1RHIM/RHIMMlkl−/− macrophages, but not in wild-type, Mlkl−/− or Ripk1RHIM/RHIMRIPK3RHIM/RHIM macrophages. Collectively, these findings indicate that the RHIM of RIPK1 is critical for preventing ZBP1/RIPK3/MLKL-dependent necroptosis during development.
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RIPK1 inhibits ZBP1-driven necroptosis during development.
Nature, 2016Co-Authors: Kim Newton, Soren Warming, Victoria C Pham, Debra L. Dugger, Katherine E. Wickliffe, Allie Maltzman, Jennie R Lill, Andreas Strasser, Merone Roose-girma, Margaret SolonAbstract:Receptor-interacting protein kinase 1 (RIPK1) promotes cell survival-mice lacking RIPK1 die perinatally, exhibiting aberrant caspase-8-dependent apoptosis and mixed lineage kinase-like (MLKL)-dependent necroptosis. However, mice expressing catalytically inactive RIPK1 are viable, and an ill-defined pro-survival function for the RIPK1 scaffold has therefore been proposed. Here we show that the RIP homotypic interaction motif (RHIM) in RIPK1 prevents the RHIM-containing adaptor protein ZBP1 (Z-DNA binding protein 1; also known as DAI or DLM1) from activating RIPK3 upstream of MLKL. Ripk1RHIM/RHIM mice that expressed mutant RIPK1 with critical RHIM residues IQIG mutated to AAAA died around birth and exhibited RIPK3 autophosphorylation on Thr231 and Ser232, which is a hallmark of necroptosis, in the skin and thymus. Blocking necroptosis with catalytically inactive RIPK3(D161N), RHIM mutant RIPK3, RIPK3 deficiency, or MLKL deficiency prevented lethality in Ripk1RHIM/RHIM mice. Loss of ZBP1, which engages RIPK3 in response to certain viruses but previously had no defined role in development, also prevented perinatal lethality in Ripk1RHIM/RHIM mice. Consistent with the RHIM of RIPK1 functioning as a brake that prevents ZBP1 from engaging the RIPK3 RHIM, ZBP1 interacted with RIPK3 in Ripk1RHIM/RHIMMlkl-/- macrophages, but not in wild-type, Mlkl-/- or Ripk1RHIM/RHIMRIPK3RHIM/RHIM macrophages. Collectively, these findings indicate that the RHIM of RIPK1 is critical for preventing ZBP1/RIPK3/MLKL-dependent necroptosis during development.
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RIPK3 deficiency or catalytically inactive ripk1 provides greater benefit than mlkl deficiency in mouse models of inflammation and tissue injury
Cell Death & Differentiation, 2016Co-Authors: Kim Newton, Joan M Greve, Maj Hedehus, Baby Martinmcnulty, Rick Carano, Nick Van Bruggen, Lisa E Bernstein, Debra L. Dugger, Allie Maltzman, Xiumin WuAbstract:Necroptosis is a caspase-independent form of cell death that is triggered by activation of the receptor interacting serine/threonine kinase 3 (RIPK3) and phosphorylation of its pseudokinase substrate mixed lineage kinase-like (MLKL), which then translocates to membranes and promotes cell lysis. Activation of RIPK3 is regulated by the kinase RIPK1. Here we analyze the contribution of RIPK1, RIPK3, or MLKL to several mouse disease models. Loss of RIPK3 had no effect on lipopolysaccharide-induced sepsis, dextran sodium sulfate-induced colitis, cerulein-induced pancreatitis, hypoxia-induced cerebral edema, or the major cerebral artery occlusion stroke model. However, kidney ischemia–reperfusion injury, myocardial infarction, and systemic inflammation associated with A20 deficiency or high-dose tumor necrosis factor (TNF) were ameliorated by RIPK3 deficiency. Catalytically inactive RIPK1 was also beneficial in the kidney ischemia–reperfusion injury model, the high-dose TNF model, and in A20−/− mice. Interestingly, MLKL deficiency offered less protection in the kidney ischemia–reperfusion injury model and no benefit in A20−/− mice, consistent with necroptosis-independent functions for RIPK1 and RIPK3. Combined loss of RIPK3 (or MLKL) and caspase-8 largely prevented the cytokine storm, hypothermia, and morbidity induced by TNF, suggesting that the triggering event in this model is a combination of apoptosis and necroptosis. Tissue-specific RIPK3 deletion identified intestinal epithelial cells as the major target organ. Together these data emphasize that MLKL deficiency rather than RIPK1 inactivation or RIPK3 deficiency must be examined to implicate a role for necroptosis in disease.
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ripk1 and RIPK3 critical regulators of inflammation and cell death
Trends in Cell Biology, 2015Co-Authors: Kim NewtonAbstract:RIPK1 and RIPK3 (receptor-interacting serine/threonine protein kinases 1/3) interact by virtue of their RIP homotypic interaction motifs to mediate a form of cell death called necroptosis, although mice lacking these kinases have very different phenotypes. RIPK1-deficient mice die soon after birth, whereas RIPK3-deficient mice are healthy. Necroptosis involves cell rupture and is triggered by tumor necrosis factor (TNF), Toll-like receptors (TLRs), or the T cell receptor (TCR) when pro-apoptotic caspase-8 is inhibited. Various mouse models of disease are ameliorated by RIPK3 deficiency, suggesting that necroptosis contributes to pathology. Genetic rescue experiments now reveal why RIPK3-deficient are viable but RIPK1-deficient mice are not. These and other experiments indicate unexpected complexity in the regulation of both apoptosis and necroptosis by RIPK1 and RIPK3.
Peter Vandenabeele - One of the best experts on this subject based on the ideXlab platform.
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ripk1 or RIPK3 deletion prevents progressive neuronal cell death and improves memory function after traumatic brain injury
Acta neuropathologica communications, 2021Co-Authors: Antonia Clarissa Wehn, Peter Vandenabeele, Igor Khalin, Marco Duering, Farida Hellal, Carsten Culmsee, Nikolaus Plesnila, Nicole Angela TerpolilliAbstract:Traumatic brain injury (TBI) causes acute and subacute tissue damage, but is also associated with chronic inflammation and progressive loss of brain tissue months and years after the initial event. The trigger and the subsequent molecular mechanisms causing chronic brain injury after TBI are not well understood. The aim of the current study was therefore to investigate the hypothesis that necroptosis, a form a programmed cell death mediated by the interaction of Receptor Interacting Protein Kinases (RIPK) 1 and 3, is involved in this process. Neuron-specific RIPK1- or RIPK3-deficient mice and their wild-type littermates were subjected to experimental TBI by controlled cortical impact. Posttraumatic brain damage and functional outcome were assessed longitudinally by repetitive magnetic resonance imaging (MRI) and behavioral tests (beam walk, Barnes maze, and tail suspension), respectively, for up to three months after injury. Thereafter, brains were investigated by immunohistochemistry for the necroptotic marker phosphorylated mixed lineage kinase like protein(pMLKL) and activation of astrocytes and microglia. WT mice showed progressive chronic brain damage in cortex and hippocampus and increased levels of pMLKL after TBI. Chronic brain damage occurred almost exclusively in areas with iron deposits and was significantly reduced in RIPK1- or RIPK3-deficient mice by up to 80%. Neuroprotection was accompanied by a reduction of astrocyte and microglia activation and improved memory function. The data of the current study suggest that progressive chronic brain damage and cognitive decline after TBI depend on the expression of RIPK1/3 in neurons. Hence, inhibition of necroptosis signaling may represent a novel therapeutic target for the prevention of chronic post-traumatic brain damage.
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Additional file 1 of RIPK1 or RIPK3 deletion prevents progressive neuronal cell death and improves memory function after traumatic brain injury
2021Co-Authors: Antonia Clarissa Wehn, Peter Vandenabeele, Igor Khalin, Marco Duering, Farida Hellal, Carsten Culmsee, Nikolaus Plesnila, Nicole Angela TerpolilliAbstract:Additional File 1 Supplementary Fig. S1. Genotyping of RIPK1 and RIPK3 deficient mice and proof of neuronal specific RIPK1 knock-out in RIPK1flox/floxCamk2CreERT2 mice. a. Neuron specific RIPK1 deficient mice used for experiments were heterozygous for Camk2CreERT2 and homozygous for the floxed RIPK1 allele. Littermate controls were also homozygous for the floxed RIPK1 allele, but did not express the Cre recombinase. b. Global RIPK3 deficient mice were homozygous for disrupted allele, while control mice expressed only the wild type gene. c. and d. To demonstrate specific neuron specific RIPK1 deficiency in induced RIPK1flox/floxCamk2CreERT2 mice, we performed immunohistochemistry for RIPK1 and NeuN, a neuronal marker. In the cortex of control mice RIPK1 was almost exclusively expressed in neurons (upper panels), while in induced RIPK1flox/floxCamk2CreERT2 mice RIPK1 staining was significantly reduced (lower panels) to 20% of baseline (d). Additional File 1 Supplementary Fig. 2 Body weight and physical condition after experimental TBI. a. and b. Weight after TBI. Animals recovered from weight loss directly after trauma within one week after injury; in the following observation period weight constantly increased. No differences were detected between CCI and sham-operated animals in the RIPK1 (a) and RIPK3 (b) groups. c. and d. General health score to assess recovery. All animals’ general condition transiently worsened in the perioperative phase with a peak at day 1 after TBI, but returned to baseline within one week. There was no difference between groups, c. RIPK1, d. RIPK3. Data are presented as mean ± SD; n = 5 for sham, n = 8–10 for TBI. Additional File 1 Supplementary Fig. 3. Individual lesion volume progression for a. RIP1 and b. RIP3 deficient mice. Additional File 1 Supplementary Fig. 4. RIPK3 deficiency does not affect acute brain injury after TBI. No differences in lesion volume as assessed by histology was detected between RIPK3 knockout mice and C57BL/6 wild type controls at 24 h after TBI. Data are presented as mean ± SD; n = 10. Additional File 1 Supplementary Fig. 5. Lesion volumes by MRI and histology. a. T2-weighted MRI and Nissl stained coronal section three months after injury. Lesion volume was quantified in T2-weighted MRI images as well as Nissl stained sections obtained in the same animals three months post injury. b. Correlation analysis of lesion volumes assessed by histomorphometry or T2-weighted MRI revealed a strong positive correlation between both methods. Differences in measured lesion size are due to shrinking of tissue in the fixation process, with a shrinking factor of 0.77 ± 0.23. c.—f. Quantification of lesion volume (c. RIPK1, d. RIPK3) as well as hippocampal damage (e. RIPK1, f. RIPK3) using both methods. Data are presented as mean ± SD; n = 8–10 for TBI. Pearson correlation, Students t-test for parametric and Man-Whitney-Rank-Sum test for non-parametric data were used. *p
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inhibitors targeting ripk1 RIPK3 old and new drugs
Trends in Pharmacological Sciences, 2020Co-Authors: Sofie Martens, Sam Hofmans, Koen Augustyns, Wim Declercq, Peter VandenabeeleAbstract:The scaffolding function of receptor-interacting protein kinase 1 (RIPK1) regulates prosurvival signaling and inflammatory gene expression, while its kinase activity mediates both apoptosis and necroptosis; the latter involving RIPK3 kinase activity. The mutual transition between the scaffold and kinase functions of RIPK1 is regulated by (de)ubiquitylation and (de)phosphorylation. RIPK1-mediated cell death leads to disruption of epithelial barriers and/or release of damage-associated molecular patterns (DAMPs), cytokines, and chemokines, propagating inflammatory and degenerative diseases. Many drug development programs have pursued targeting RIPK1, and to a lesser extent RIPK3 kinase activity. In this review, we classify existing and novel small-molecule drugs based on their pharmacodynamic (PD) type I, II, and III binding mode. Finally, we discuss their applicability and therapeutic potential in inflammatory and degenerative experimental disease models.
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nuclear RIPK3 and mlkl contribute to cytosolic necrosome formation and necroptosis
Communications Biology, 2018Co-Authors: Kathrin Weber, Ria Roelandt, Inge Bruggeman, Yann Estornes, Peter VandenabeeleAbstract:Necroptotic signaling converges in the assembly of a cytosolic signaling platform, the necrosome, with the activation of its downstream effector, MLKL. RIPK1 and RIPK3, key components of the necrosome, act as signaling intermediates for the activation of MLKL. We report that RIPK3 and MLKL continuously shuttle between the nucleus and the cytoplasm, whereas RIPK1 is constitutively present in both compartments. During TNF-induced necroptosis, nuclear RIPK1 becomes ubiquitinated, after which nuclear MLKL becomes phosphorylated and oligomerized. Pharmacological inhibition of the nuclear export machinery leads to retention of RIPK3 and MLKL in the nucleus, prevents the nucleation of cytosolic RIPK3/MLKL oligomerization, and reduces cell death. Our results suggest that passage of necroptotic signaling components through the nucleus is a mechanism for regulating cytosolic necrosome formation and consequently necroptotic cell death.
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Initiation and execution mechanisms of necroptosis: an overview
Cell Death & Differentiation, 2017Co-Authors: Sasker Grootjans, Tom Vanden Berghe, Peter VandenabeeleAbstract:Necroptosis is a form of regulated cell death, which is induced by ligand binding to TNF family death domain receptors, pattern recognizing receptors and virus sensors. The common feature of these receptor systems is the implication of proteins, which contain a receptor interaction protein kinase (RIPK) homology interaction motif (RHIM) mediating recruitment and activation of receptor-interacting protein kinase 3 (RIPK3), which ultimately activates the necroptosis executioner mixed lineage kinase domain-like (MLKL). In case of the TNF family members, the initiator is the survival- and cell death-regulating RIPK1 kinase, in the case of Toll-like receptor 3/4 (TLR3/4), a RHIM-containing adaptor, called TRIF, while in the case of Z-DNA-binding protein ZBP1/DAI, the cytosolic viral sensor itself contains a RHIM domain. In this review, we discuss the different protein complexes that serve as nucleation platforms for necroptosis and the mechanism of execution of necroptosis. Transgenic models (knockout, kinase-dead knock-in) and pharmacologic inhibition indicate that RIPK1, RIPK3 or MLKL are implicated in many inflammatory, degenerative and infectious diseases. However, the conclusion of necroptosis being solely involved in the etiology of diseases is blurred by the pleiotropic roles of RIPK1 and RIPK3 in other cellular processes such as apoptosis and inflammasome activation.
James E. Vince - One of the best experts on this subject based on the ideXlab platform.
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ripk1 regulates RIPK3 mlkl driven systemic inflammation and emergency hematopoiesis
Cell, 2014Co-Authors: Joseph M Evans, James A Rickard, Najoua Lalaoui, Tewhiti Rogers, Joanne A Odonnell, James E. VinceAbstract:Summary Upon ligand binding, RIPK1 is recruited to tumor necrosis factor receptor superfamily (TNFRSF) and Toll-like receptor (TLR) complexes promoting prosurvival and inflammatory signaling. RIPK1 also directly regulates caspase-8-mediated apoptosis or, if caspase-8 activity is blocked, RIPK3-MLKL-dependent necroptosis. We show that C57BL/6 Ripk1 −/− mice die at birth of systemic inflammation that was not transferable by the hematopoietic compartment. However, Ripk1 −/− progenitors failed to engraft lethally irradiated hosts properly. Blocking TNF reversed this defect in emergency hematopoiesis but, surprisingly, Tnfr1 deficiency did not prevent inflammation in Ripk1 −/− neonates. Deletion of RIPK3 or Mlkl , but not Casp 8, prevented extracellular release of the necroptotic DAMP, IL-33, and reduced Myd88 -dependent inflammation. Reduced inflammation in the Ripk1 −/− RIPK3 −/− , Ripk1 −/− Mlkl −/− , and Ripk1 −/− Myd88 −/− mice prevented neonatal lethality, but only Ripk1 −/− RIPK3 −/− Casp8 −/− mice survived past weaning. These results reveal a key function for RIPK1 in inhibiting necroptosis and, thereby, a role in limiting, not only promoting, inflammation.
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ciaps and xiap regulate myelopoiesis through cytokine production in an ripk1 and RIPK3 dependent manner
Blood, 2014Co-Authors: Najoua Lalaoui, Weilynn W Wong, James E. Vince, Kate E Lawlor, Diep ChauAbstract:Loss of inhibitor of apoptosis proteins (IAPs), particularly cIAP1, can promote production of tumor necrosis factor (TNF) and sensitize cancer cell lines to TNF-induced necroptosis by promoting formation of a death-inducing signaling complex containing receptor-interacting serine/threonine-protein kinase (RIPK) 1 and 3. To define the role of IAPs in myelopoiesis, we generated a mouse with cIAP1, cIAP2, and XIAP deleted in the myeloid lineage. Loss of cIAPs and XIAP in the myeloid lineage caused overproduction of many proinflammatory cytokines, resulting in granulocytosis and severe sterile inflammation. In vitro differentiation of macrophages from bone marrow in the absence of cIAPs and XIAP led to detectable levels of TNF and resulted in reduced numbers of mature macrophages. The cytokine production and consequent cell death caused by IAP depletion was attenuated by loss or inhibition of TNF or TNF receptor 1. The loss of RIPK1 or RIPK3, but not the RIPK3 substrate mixed lineage kinase domain-like protein, attenuated TNF secretion and thereby prevented apoptotic cell death and not necrosis. Our results demonstrate that cIAPs and XIAP together restrain RIPK1- and RIPK3-dependent cytokine production in myeloid cells to critically regulate myeloid homeostasis.
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tnf can activate RIPK3 and cause programmed necrosis in the absence of ripk1
Cell Death and Disease, 2013Co-Authors: W D Cook, Donia M Moujalled, Toru Okamoto, James E. Vince, Kate E Lawlor, J J MurphyAbstract:Ligation of tumor necrosis factor receptor 1 (TNFR1) can cause cell death by caspase 8 or receptor-interacting protein kinase 1 (RIPK1)- and RIPK3-dependent mechanisms. It has been assumed that because RIPK1 bears a death domain (DD), but RIPK3 does not, RIPK1 is necessary for recruitment of RIPK3 into signaling and death-inducing complexes. To test this assumption, we expressed elevated levels of RIPK3 in murine embryonic fibroblasts (MEFs) from wild-type (WT) and gene-deleted mice, and exposed them to TNF. Neither treatment with TNF nor overexpression of RIPK3 alone caused MEFs to die, but when levels of RIPK3 were increased, addition of TNF killed WT, Ripk1−/−, caspase 8−/−, and Bax−/−/Bak−/− MEFs, even in the presence of the broad-spectrum caspase inhibitor Q-VD-OPh. In contrast, Tnfr1−/− and Tradd−/− MEFs did not die. These results show for the first time that in the absence of RIPK1, TNF can activate RIPK3 to induce cell death both by a caspase 8-dependent mechanism and by a separate Bax/Bak- and caspase-independent mechanism. RIPK1 is therefore not essential for TNF to activate RIPK3 to induce necroptosis nor for the formation of a functional ripoptosome/necrosome.
Kate E Lawlor - One of the best experts on this subject based on the ideXlab platform.
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mutations that prevent caspase cleavage of ripk1 cause autoinflammatory disease
Nature, 2020Co-Authors: Najoua Lalaoui, Diep Chau, Stuart Edward Boyden, Mario Stoffels, Tobias Kratina, Geryl Wood, Kate E Lawlor, Deborah L. StoneAbstract:RIPK1 is a key regulator of innate immune signalling pathways. To ensure an optimal inflammatory response, RIPK1 is regulated post-translationally by well-characterized ubiquitylation and phosphorylation events, as well as by caspase-8-mediated cleavage1–7. The physiological relevance of this cleavage event remains unclear, although it is thought to inhibit activation of RIPK3 and necroptosis8. Here we show that the heterozygous missense mutations D324N, D324H and D324Y prevent caspase cleavage of RIPK1 in humans and result in an early-onset periodic fever syndrome and severe intermittent lymphadenopathy—a condition we term ‘cleavage-resistant RIPK1-induced autoinflammatory syndrome’. To define the mechanism for this disease, we generated a cleavage-resistant Ripk1D325A mutant mouse strain. Whereas Ripk1−/− mice died postnatally from systemic inflammation, Ripk1D325A/D325A mice died during embryogenesis. Embryonic lethality was completely prevented by the combined loss of Casp8 and RIPK3, but not by loss of RIPK3 or Mlkl alone. Loss of RIPK1 kinase activity also prevented Ripk1D325A/D325A embryonic lethality, although the mice died before weaning from multi-organ inflammation in a RIPK3-dependent manner. Consistently, Ripk1D325A/D325A and Ripk1D325A/+ cells were hypersensitive to RIPK3-dependent TNF-induced apoptosis and necroptosis. Heterozygous Ripk1D325A/+ mice were viable and grossly normal, but were hyper-responsive to inflammatory stimuli in vivo. Our results demonstrate the importance of caspase-mediated RIPK1 cleavage during embryonic development and show that caspase cleavage of RIPK1 not only inhibits necroptosis but also maintains inflammatory homeostasis throughout life. Heterozygous mutateons in the caspase-8 cleavage site of RIPK1 cause a range of autoinflammatory symptoms in humans, and caspase-8 cleavage of RIPK1 in a mouse model limits TNF-induced cell death and inflammation.
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ciaps and xiap regulate myelopoiesis through cytokine production in an ripk1 and RIPK3 dependent manner
Blood, 2014Co-Authors: Najoua Lalaoui, Weilynn W Wong, James E. Vince, Kate E Lawlor, Diep ChauAbstract:Loss of inhibitor of apoptosis proteins (IAPs), particularly cIAP1, can promote production of tumor necrosis factor (TNF) and sensitize cancer cell lines to TNF-induced necroptosis by promoting formation of a death-inducing signaling complex containing receptor-interacting serine/threonine-protein kinase (RIPK) 1 and 3. To define the role of IAPs in myelopoiesis, we generated a mouse with cIAP1, cIAP2, and XIAP deleted in the myeloid lineage. Loss of cIAPs and XIAP in the myeloid lineage caused overproduction of many proinflammatory cytokines, resulting in granulocytosis and severe sterile inflammation. In vitro differentiation of macrophages from bone marrow in the absence of cIAPs and XIAP led to detectable levels of TNF and resulted in reduced numbers of mature macrophages. The cytokine production and consequent cell death caused by IAP depletion was attenuated by loss or inhibition of TNF or TNF receptor 1. The loss of RIPK1 or RIPK3, but not the RIPK3 substrate mixed lineage kinase domain-like protein, attenuated TNF secretion and thereby prevented apoptotic cell death and not necrosis. Our results demonstrate that cIAPs and XIAP together restrain RIPK1- and RIPK3-dependent cytokine production in myeloid cells to critically regulate myeloid homeostasis.
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tnf can activate RIPK3 and cause programmed necrosis in the absence of ripk1
Cell Death and Disease, 2013Co-Authors: W D Cook, Donia M Moujalled, Toru Okamoto, James E. Vince, Kate E Lawlor, J J MurphyAbstract:Ligation of tumor necrosis factor receptor 1 (TNFR1) can cause cell death by caspase 8 or receptor-interacting protein kinase 1 (RIPK1)- and RIPK3-dependent mechanisms. It has been assumed that because RIPK1 bears a death domain (DD), but RIPK3 does not, RIPK1 is necessary for recruitment of RIPK3 into signaling and death-inducing complexes. To test this assumption, we expressed elevated levels of RIPK3 in murine embryonic fibroblasts (MEFs) from wild-type (WT) and gene-deleted mice, and exposed them to TNF. Neither treatment with TNF nor overexpression of RIPK3 alone caused MEFs to die, but when levels of RIPK3 were increased, addition of TNF killed WT, Ripk1−/−, caspase 8−/−, and Bax−/−/Bak−/− MEFs, even in the presence of the broad-spectrum caspase inhibitor Q-VD-OPh. In contrast, Tnfr1−/− and Tradd−/− MEFs did not die. These results show for the first time that in the absence of RIPK1, TNF can activate RIPK3 to induce cell death both by a caspase 8-dependent mechanism and by a separate Bax/Bak- and caspase-independent mechanism. RIPK1 is therefore not essential for TNF to activate RIPK3 to induce necroptosis nor for the formation of a functional ripoptosome/necrosome.