scholarly journals The Human Cytomegalovirus UL36 Gene Controls Caspase-Dependent and -Independent Cell Death Programs Activated by Infection of Monocytes Differentiating to Macrophages

2010 ◽  
Vol 84 (10) ◽  
pp. 5108-5123 ◽  
Author(s):  
A. Louise McCormick ◽  
Linda Roback ◽  
Devon Livingston-Rosanoff ◽  
Courtney St. Clair
Keyword(s):  
Cell Death ◽  
Human Cytomegalovirus ◽  
Caspase 8 ◽  
Specific Cell ◽  
Macrophage Differentiation ◽  
Antiviral Responses ◽  
Cell Death Pathways ◽  
Cell Death Pathway ◽  
The Impact ◽  
Late Stages

ABSTRACT The cellular protease caspase-8 activates extrinsic apoptosis and also functions to promote monocyte-to-macrophage differentiation. Differentiation-induced alterations to antiviral caspase-8-dependent cell death pathways are unclear. Here, we show THP-1 monocyte-to-macrophage differentiation alters the specific cell death pathways activated in response to human cytomegalovirus (HCMV) infection. Employing viruses with mutations in UL36, the gene that encodes the viral inhibitor of caspase-8 activation (vICA), our data indicate that both caspase-dependent and -independent death pathways are activated in response to infection. Activation of caspase-dependent and -independent cell death responses restricted growth of vICA-deficient viruses, and vICA/pUL36 inhibited either response. Thus, these studies also reveal that the UL36 gene controls a caspase-independent cell death pathway. The impact of caspases on control of antiviral responses differed at early and late stages of macrophage differentiation. Early in differentiation, vICA-deficient virus-induced cell death was dependent on caspases and inhibited by the pan-caspase inhibitor z-VAD(OMe)-fluoromethyl ketone. In contrast, virus-induced death at late times of differentiation was caspase independent. Additional unlabeled and fluorescent inhibitors indicated that caspase-8 promoted death from within infected cells at early but not late stages of differentiation. These data highlight the multifunctional role of vICA/pUL36 as HCMV encounters various antiviral responses during macrophage differentiation.

scholarly journals Mouse cytomegalovirus M36 and M45 death suppressors cooperate to prevent inflammation resulting from antiviral programmed cell death pathways

2017 ◽  
Vol 114 (13) ◽  
pp. E2786-E2795 ◽  
Author(s):  
Lisa P. Daley-Bauer ◽  
Linda Roback ◽  
Lynsey N. Crosby ◽  
A. Louise McCormick ◽  
Yanjun Feng ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Double Mutant ◽  
Kinase Domain ◽  
Murine Cytomegalovirus ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Antiviral Responses ◽  
Cell Death Pathways ◽  
Infected Cells

The complex interplay between caspase-8 and receptor-interacting protein (RIP) kinase RIP 3 (RIPK3) driving extrinsic apoptosis and necroptosis is not fully understood. Murine cytomegalovirus triggers both apoptosis and necroptosis in infected cells; however, encoded inhibitors of caspase-8 activity (M36) and RIP3 signaling (M45) suppress these antiviral responses. Here, we report that this virus activates caspase-8 in macrophages to trigger apoptosis that gives rise to secondary necroptosis. Infection with double-mutant ΔM36/M45mutRHIM virus reveals a signaling pattern in which caspase-8 activates caspase-3 to drive apoptosis with subsequent RIP3-dependent activation of mixed lineage kinase domain-like (MLKL) leading to necroptosis. This combined cell death signaling is highly inflammatory, greater than either apoptosis induced by ΔM36 or necroptosis induced by M45mutRHIM virus. IL-6 production by macrophages is dramatically increased during double-mutant virus infection and correlates with faster antiviral responses in the host. Collaboratively, M36 and M45 target caspase-8 and RIP3 pathways together to suppress this proinflammatory cell death. This study reveals the effect of antiviral programmed cell death pathways on inflammation, shows that caspase-8 activation may go hand-in-hand with necroptosis in macrophages, and revises current understanding of independent and collaborative functions of M36 and M45 in blocking apoptotic and necroptotic cell death responses.

scholarly journals Targeting Caspase 8: Using Structural and Ligand-Based Approaches to Identify Potential Leads for the Treatment of Multi-Neurodegenerative Diseases

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1827 ◽  
Author(s):  
Khurshid Ahmad ◽  
Vishal M. Balaramnavar ◽  
Navaneet Chaturvedi ◽  
Saif Khan ◽  
Shafiul Haque ◽  
...  
Keyword(s):  
Cell Death ◽  
Neurodegenerative Diseases ◽  
Structural Information ◽  
Apoptotic Cell ◽  
Critical Role ◽  
Caspase 8 ◽  
Cell Death Pathways ◽  
Cell Death Pathway ◽  
Zinc Database ◽  
Dynamics Simulations

Caspase 8 is a central player in the apoptotic cell death pathway and is also essential for cytokine processing. The critical role of this protease in cell death pathways has generated research interest because its activation has also been linked with neural cell death. Thus, blocking the activity of caspase 8 is considered a potential therapy for neurodegenerative diseases. To extend the repertoire of caspase 8 inhibitors, we employed several computational approaches to identify potential caspase 8 inhibitors. Based on the structural information of reported inhibitors, we designed several individual and consensus pharmacophore models and then screened the ZINC database, which contains 105,480 compounds. Screening generated 5332 candidates, but after applying stringent criteria only two candidate compounds, ZINC19370490 and ZINC04534268, were evaluated by molecular dynamics simulations and subjected to Molecular Mechanics/Poisson Boltzmann Surface Area (MM-PBSA) analysis. These compounds were stable throughout simulations and interacted with targeted protein by forming hydrogen and van der Waal bonds. MM-PBSA analysis showed that these compounds were comparable or better than reported caspase 8 inhibitors. Furthermore, their physical properties were found to be acceptable, and they are non-toxic according to the ADMET online server. We suggest that the inhibitory efficacies of ZINC19370490 and ZINC04534268 be subjected to experimental validation.

scholarly journals Human cytomegalovirus protein pUL36: a dual cell death pathway inhibitor

2020 ◽  
Author(s):  
Alice Fletcher-Etherington ◽  
Luis Nobre ◽  
Katie Nightingale ◽  
Robin Antrobus ◽  
Jenna Nichols ◽  
...  
Keyword(s):  
Cell Death ◽  
Human Cytomegalovirus ◽  
Kinase Domain ◽  
Human Pathogen ◽  
Proteolytic Activation ◽  
Proteomic Screen ◽  
Cell Death Pathways ◽  
Cell Death Pathway ◽  
Human Proteins ◽  
Necessary And Sufficient

ABSTRACTHuman cytomegalovirus (HCMV) is an important human pathogen and a paradigm of intrinsic, innate and adaptive viral immune evasion. Here, we employed multiplexed tandem mass tag-based proteomics to characterise host proteins targeted for degradation late during HCMV infection. This approach revealed that mixed lineage kinase domain-like protein (MLKL), a key terminal mediator of cellular necroptosis, was rapidly and persistently degraded by the minimally passaged HCMV strain Merlin but not the extensively passaged strain AD169. The strain Merlin viral inhibitor of apoptosis pUL36 was necessary and sufficient both to degrade MLKL and to inhibit necroptosis. Furthermore, mutation of pUL36 Cys131 abrogated MLKL degradation and restored necroptosis. As the same residue is also required for pUL36-mediated inhibition of apoptosis by preventing proteolytic activation of pro-caspase 8, we define pUL36 as a multifunctional inhibitor of both apoptotic and necroptotic cell death.SIGNIFICANCE STATEMENTCell death is a key defence against viral infection, preventing spread from infected to uninfected cells. Correspondingly, certain viruses encode inhibitors of apoptotic and necroptotic cell death pathways in order to facilitate their persistence. Human cytomegalovirus (HCMV) is an important human pathogen that can block apoptosis, but hitherto it has been unclear whether or how the virus blocks necroptosis. Here, we used a proteomic screen to identify human proteins targeted for destruction by HCMV, finding that the key necroptosis mediator MLKL is degraded throughout infection. MLKL is targeted for degradation by HCMV protein pUL36, which is also instrumental in inhibiting apoptosis. Thus, pUL36 is a dual cell death pathway inhibitor, and may represent an important therapeutic target.

Abstract 143: A Novel TAK1 Signaling Network Regulating Programmed Necrosis and Myocardial Remodeling

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Qinghang Liu ◽  
Lei Li ◽  
Yi Chen ◽  
Jessica Doan ◽  
Jeffery Molkentin
Keyword(s):  
Heart Failure ◽  
Cell Death ◽  
Cell Survival ◽  
Cardiac Fibrosis ◽  
Signaling Network ◽  
Specific Gene ◽  
Caspase 8 ◽  
Programmed Necrosis ◽  
Genetic Ablation ◽  
Cell Death Pathway

We recently identified a novel signaling molecule, TAK1 (TGFβ-activated kinase 1, also known as MAP3K7), as a key regulator of the hypertrophic signaling network. Importantly, TAK1 is activated in mouse models of heart failure as well as in diseased human myocardium. Here, we defined a previously unidentified, novel role for TAK1 in promoting cardiac cell survival and homeostasis using cardiac-specific gene-targeted mice. Indeed, cardiac-specific ablation of TAK1 in mice using a Cre-LoxP system showed enhanced pathological cardiac remodeling and massive cell death, and these mice gradually developed heart failure and spontaneous death. Remarkably, ablation of TNF receptor 1 (TNFR1) largely rescued the pathological phenotype of TAK1-deficient mice, preventing early lethality and cardiac fibrosis, suggesting that TNFR1 signaling is critical in mediating adverse remodeling and heart failure associated with TAK1 deficiency. Genetic or pharmacological inactivation of TAK1 in cardiomyocytes markedly induced programmed necrosis and apoptosis in response to TNFα. Conversely, overexpression of the constitutively active TAK1 mutant, or TAK1 plus its activator TAB1, protected cardiomyocytes from TNFα-induced cell death. Mechanistically, inactivation of TAK1 promoted formation of the necroptotic cell death complex consisting of RIP1, RIP3, caspase 8, and FADD. Genetic ablation of RIP1, RIP3, caspase 8, or FADD largely blocked TNFα-induced cell death in TAK1-deficient cells, whereas deletion of Bax/Bak or cyclophilin D showed no effects. Further, IKK/NFκB-mediated cell survival signaling was greatly impaired in TAK1-deficient cardiomyocytes. Taken together, our data indicate that TAK1 functions as a critical “molecular switch” in TNFα-induced programmed necrosis in cardiomyocytes, by interacting with the RIP1/3-caspase 8-FADD cell death pathway as well as the IKK-NFκB cell survival pathway. These findings thus define an important TAK1-mediated cardio-protective signaling network in the heart, which may suggest new therapeutic strategies in the treatment of heart disease.

scholarly journals AC-YVAD-CMK Inhibits Pyroptosis and Improves Functional Outcome after Intracerebral Hemorrhage

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xiao Lin ◽  
Haotuo Ye ◽  
Felix Siaw-Debrah ◽  
Sishi Pan ◽  
Zibin He ◽  
...  
Keyword(s):  
Cell Death ◽  
Intracerebral Hemorrhage ◽  
Cell Damage ◽  
Neuronal Cell ◽  
Neurological Function ◽  
Inflammatory Factors ◽  
Neuroprotective Effects ◽  
Caspase 1 ◽  
Cell Death Pathways ◽  
Cell Death Pathway

Intracerebral hemorrhage (ICH) refers to bleeding in the brain and is associated with the release of large amount of inflammasomes, and the activation of different cell death pathways. These cell death pathways lead to removal of inactivated and damaged cells and also result in neuronal cell damage. Pyroptosis is a newly discovered cell death pathway that has gained attention in recent years. This pathway mainly depends on activation of caspase-1-mediated cascades to cause cell death. We tested a well-known selective inhibitor of caspase-1, AC-YVAD-CMK, which has previously been found to have neuroprotective effects in ICH mice model, to ascertain its effects on the activation of inflammasomes mediated pyroptosis. Our results showed that AC-YVAD-CMK could reduce caspase-1 activation and inhibit IL-1β production and maturation, but has no effect on NLRP3 expression, an upstream inflammatory complex. AC-YVAD-CMK administration also resulted in reduction in M1-type microglia polarization around the hematoma, while increasing the number of M2-type cells. Furthermore, AC-YVAD-CMK treated mice showed some recovery of neurological function after hemorrhage especially at the hyperacute and subacute stage resulting in some degree of limb movement. In conclusion, we are of the view that AC-YVAD-CMK could inhibit pyroptosis, decrease the secretion or activation of inflammatory factors, and affect the polarization of microglia resulting in improvement of neurological function after ICH.

scholarly journals ZBP1 induces inflammatory signaling via RIPK3 and promotes SARS-CoV-2-induced cytokine expression

2021 ◽  
Author(s):  
Ruoshi Peng ◽  
Xuan Wang-Kan ◽  
Manja Idorn ◽  
Felix Y Zhou ◽  
Susana L Orozco ◽  
...  
Keyword(s):  
Cell Death ◽  
Signaling Pathway ◽  
Kinase Activity ◽  
Caspase 8 ◽  
Dependent Manner ◽  
Innate Immune Responses ◽  
Inflammatory Signaling ◽  
Antiviral Responses ◽  
Nucleic Acid Sensor ◽  
Activity Dependent

AbstractCOVID-19 caused by the SARS-CoV-2 virus remains a threat to global health. The disease severity is mediated by cell death and inflammation, which regulate both the antiviral and the pathological innate immune responses. ZBP1, an interferon-induced cytosolic nucleic acid sensor, facilitates antiviral responses via RIPK3. Although ZBP1-mediated cell death is widely described, whether and how it promotes inflammatory signaling is unclear. Here, we report a ZBP1-induced inflammatory signaling pathway that depends on ubiquitination and RIPK3’s scaffolding ability independently of cell death. In human cells, ZBP1 associates with RIPK1 and RIPK3 as well as ubiquitin ligases cIAP1 and LUBAC. RIPK1 and ZBP1 are ubiquitinated to promote TAK1- and IKK-mediated inflammatory signaling. Additionally, RIPK1 recruits the p43/41-caspase-8-p43-FLIP heterodimer to suppress RIPK3 kinase activity, which otherwise promotes inflammatory signaling in a kinase activity-dependent manner. Lastly, we show that ZBP1 contributes to SARS-CoV-2-induced cytokine production. Taken together, we describe a ZBP1-RIPK1-RIPK3-mediated inflammatory signaling pathway relayed by the scaffolding role of RIPKs and regulated by caspase-8. Our results suggest the ZBP1 pathway contributes to inflammation in response to SARS-CoV-2 infection.

scholarly journals RIPK1 is a critical modulator of both tonic and TLR-responsive inflammatory and cell death pathways in human macrophage differentiation

2018 ◽  
Vol 9 (10) ◽  
Author(s):  
Julian Buchrieser ◽  
Maria Jose Oliva-Martin ◽  
Michael D. Moore ◽  
Joshua C. D. Long ◽  
Sally A. Cowley ◽  
...  
Keyword(s):  
Cell Death ◽  
Human Macrophage ◽  
Macrophage Differentiation ◽  
Cell Death Pathways

Induction of Divergent Cell Death Pathways by Urea and Carbohydrazide Derivatives

2021 ◽  
Vol 21 ◽  
Author(s):  
Sinem Yilmaz ◽  
Fatih Tok ◽  
Esra A. Sahar ◽  
Bedia K. Kaymakcioglu ◽  
Petek B. Kirmizibayrak
Keyword(s):  
Flow Cytometry ◽  
Cell Death ◽  
Er Stress ◽  
Cytotoxic Activity ◽  
Cancer Biology ◽  
Chemotherapy Resistance ◽  
Annexin V ◽  
Double Positive ◽  
Cell Death Pathways ◽  
Cell Death Pathway

Background: The complexity of cancer biology and the development of chemotherapy resistance are two main obstacles to cancer treatment and necessitate novel anticancer molecules that target different cell death pathways. Modulation of endoplasmic reticulum (ER) stress and subsequent activation of the unfolded protein response (UPR) has been proposed as potential chemotherapeutic target, as prolonged ER stress can lead to cell death via apoptosis or necrosis. Objective: The present study aims to evaluate the molecular mechanism underlying the cytotoxic activity of selected urea and carbohydrazide derivatives. Methods: Cell proliferation assays were performed on HeLa, Capan1, MCF7, HCC1937, and MRC5 cell lines by WST-1 assay. The expression levels of selected ER stress, autophagy, and apoptosis marker proteins were compared by immunoblotting to characterize the underlying mechanism of cytotoxicity. Flow cytometry was used to detect apoptosis. Results: Of the tested cytotoxic compounds, 3a, 4a, 5a, 6a, and 1b dramatically and 5b moderately increased ER stress-related CHOP protein levels. Interestingly, 5b but not 3a, 4a, 5a, 6a, or 1b increased the expression of pro-apoptotic proteins such as cleaved PARP-1 and cleaved caspase-3 and -7. Flow-cytometry analysis further confirmed that the cytotoxic activity of 5b but not the other compounds is mediated by apoptosis, which is also demonstrated by a significant increase in the percentage of late apoptotic cells (7-AAD/annexin V double-positive cells). Conclusion: Our results suggest that changing a substituent from trifluoromethyl to nitro in urea and carbohydrazide core structure alters the cell death mechanism from apoptosis to an apoptosis-independent cell death pathway. This study shows an example of how such simple modifications of a core chemical structure could cause the induction of divergent cell death pathways.

Abstract 371: Mitochondrial Antiviral Signaling (MAVS) Protects Cardiomyocytes Under Oxidative Stress by Interfering with Bax-Mediated Cell Death

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Toshitaka Yajima ◽  
Stanley Park ◽  
Hanbing Zhou ◽  
Michinari Nakamura ◽  
Mitsuyo Machida ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Cytochrome C Release ◽  
Antiviral Signaling ◽  
Cell Death Pathway ◽  
The Impact

MAVS is a mitochondrial outer membrane protein that activates innate antiviral signaling by recognizing cytosolic viral RNAs and DNAs. While the discovery of MAVS is the first molecular evidence that links mitochondria to innate immune mechanisms, it is still unclear whether MAVS affects mitochondrial cell death as a member of caspase activation and recruitment domain (CARD)-containing proteins. We found that MAVS interacts with Bax through CARD by Yeast two-hybrid and a series of immunoprecipitation (IP) assay, which led us to hypothesize that MAVS functions not only in the innate antiviral mechanisms but also in the mitochondrial cell death pathway. Methods: 1) We examined molecular interaction between MAVS and Bax under oxidative stress by IP using isolated myocytes with H2O2 stimulation and the heart post ischemia-reperfusion (I/R). 2) We evaluated the effect of MAVS on mitochondrial membrane potential and apoptosis under H2O2 stimulation using isolated myocytes with adenoviral MAVS knockdown. 3) We investigated the impact of MAVS on %myocardial infarction (%MI) post I/R using cardiac-specific MAVS knockout (cKO) and transgenic (cTg) mice which we have originally generated. 4) We examined the effect of MAVS on recombinant Bax (rBax)-mediated cytochrome c release using isolated mitochondria from wild type (WT) and MAVS KO mice. Results: 1) The amount of Bax pulled down with MAVS was significantly increased in isolated myocytes with 0.2 mM H2O2 compared to those without stimulation (mean±SD; 1.808±0.14, n=5, p<0.001) and in the heart post I/R compared to sham (2.2±1.19, n=3, p=0.0081). 2) Myocytes with MAVS knockdown showed clear abnormalities in mitochondrial membrane potential and caspace-3 cleavage with 0.2 mM H2O2 compared to control cardiomyocytes. 3) MAVS cKO had significantly larger %MI than WT (81.9 ± 5.8% vs. 42.6 ± 13.6%, n=8, p=0.0008). In contrast, MAVS cTg had significantly smaller %MI that WT (30.0 ± 4.8% vs. 49.2 ± 4.8%, n=10, p=0.0113). 4) Mitochondria from MAVS KO exhibited cytochrome c release after incubation with 2.5 μ g of rBax while those from WT required 10 μ g of rBax. Conclusion: These results demonstrate that MAVS protects cardiomyocyte under oxidative stress by interfering with Bax-mediated cytochrome c release from mitochondria.

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.

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