scholarly journals Autophagy genes in myeloid cells counteract IFNγ-induced TNF-mediated cell death and fatal TNF-induced shock

2019 ◽  
Vol 116 (33) ◽  
pp. 16497-16506 ◽  
Author(s):  
Anthony Orvedahl ◽  
Michael R. McAllaster ◽  
Amy Sansone ◽  
Bria F. Dunlap ◽  
Chandni Desai ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Inflammatory Responses ◽  
Tissue Injury ◽  
Survival Function ◽  
Myeloid Cell ◽  
Critical Function ◽  
Interacting Protein ◽  
Autophagy Gene ◽  
Genome Wide

Host inflammatory responses must be tightly regulated to ensure effective immunity while limiting tissue injury. IFN gamma (IFNγ) primes macrophages to mount robust inflammatory responses. However, IFNγ also induces cell death, and the pathways that regulate IFNγ-induced cell death are incompletely understood. Using genome-wide CRISPR/Cas9 screening, we identified autophagy genes as central mediators of myeloid cell survival during the IFNγ response. Hypersensitivity of autophagy gene-deficient cells to IFNγ was mediated by tumor necrosis factor (TNF) signaling via receptor interacting protein kinase 1 (RIPK1)- and caspase 8-mediated cell death. Mice with myeloid cell-specific autophagy gene deficiency exhibited marked hypersensitivity to fatal systemic TNF administration. This increased mortality in myeloid autophagy gene-deficient mice required the IFNγ receptor, and mortality was completely reversed by pharmacologic inhibition of RIPK1 kinase activity. These findings provide insight into the mechanism of IFNγ-induced cell death via TNF, demonstrate a critical function of autophagy genes in promoting cell viability in the presence of inflammatory cytokines, and implicate this cell survival function in protection against mortality during the systemic inflammatory response.

scholarly journals SMAC mimetics induce autophagy-dependent apoptosis of HIV-1-infected macrophages

2020 ◽  
Vol 11 (7) ◽  
Author(s):  
Grant R. Campbell ◽  
Rachel K. To ◽  
Gang Zhang ◽  
Stephen A. Spector
Keyword(s):  
Cell Death ◽  
Hiv Infection ◽  
Cell Survival ◽  
Acute Hiv Infection ◽  
Interacting Protein ◽  
Signaling Complex ◽  
Hiv Eradication ◽  
Smac Mimetics ◽  
Smac Mimetic ◽  
Latent Hiv

Abstract Human immunodeficiency type 1 (HIV)-infected macrophages (HIV-Mφ) are a reservoir for latent HIV infection and a barrier to HIV eradication. In contrast to CD4+ T cells, HIV-Mφ are resistant to the cytopathic effects of acute HIV infection and have increased expression of cell survival factors, including X-linked inhibitor of apoptosis (XIAP), baculoviral IAP repeat containing (BIRC) 2/cIAP1, beclin-1, BCL2, BCL-xl, triggering receptor expressed on myeloid cells 1, mitofusin (MFN) 1, and MFN2. DIABLO/SMAC mimetics are therapeutic agents that affect cancer cell survival and induce cell death. We found that DIABLO/SMAC mimetics (LCL-161, AT-406 (also known as SM-406 or Debio 1143), and birinapant) selectively kill HIV-Mφ without increasing bystander cell death. DIABLO/SMAC mimetic treatment of HIV-Mφ-induced XIAP and BIRC2 degradation, leading to the induction of autophagy and the formation of a death-inducing signaling complex on phagophore membranes that includes both pro-apoptotic or necroptotic (FADD, receptor-interacting protein kinase (RIPK) 1, RIPK3, caspase 8, and MLKL) and autophagy (ATG5, ATG7, and SQSTM1) proteins. Genetic or pharmacologic inhibition of early stages of autophagy, but not late stages of autophagy, ablated this interaction and inhibited apoptosis. Furthermore, DIABLO/SMAC mimetic-mediated apoptosis of HIV-Mφ is dependent upon tumor necrosis factor signaling. Our findings thus demonstrate that DIABLO/SMAC mimetics selectively induce autophagy-dependent apoptosis in HIV-Mφ.

scholarly journals Impaired RIPK1 ubiquitination sensitizes mice to TNF toxicity and inflammatory cell death

2020 ◽  
Author(s):  
Matthias Kist ◽  
László G. Kőműves ◽  
Tatiana Goncharov ◽  
Debra L. Dugger ◽  
Charles Yu ◽  
...  
Keyword(s):  
Cell Death ◽  
Inflammatory Responses ◽  
Mapk Signaling ◽  
Embryonic Lethality ◽  
Mapk Activation ◽  
Interacting Protein ◽  
Signaling Complex ◽  
Ubiquitination Site ◽  
Lysine Residues ◽  
The Stability

Abstract Receptor-interacting protein 1 (RIP1; RIPK1) is a key regulator of multiple signaling pathways that mediate inflammatory responses and cell death. TNF-TNFR1 triggered signaling complex formation, subsequent NF-κB and MAPK activation and induction of cell death involve RIPK1 ubiquitination at several lysine residues including Lys376 and Lys115. Here we show that mutating the ubiquitination site K376 of RIPK1 (K376R) in mice activates cell death resulting in embryonic lethality. In contrast to Ripk1K376R/K376R mice, Ripk1K115R/K115R mice reached adulthood and showed slightly higher responsiveness to TNF-induced death. Cell death observed in Ripk1K376R/K376R embryos relied on RIPK1 kinase activity as administration of RIPK1 inhibitor GNE684 to pregnant heterozygous mice effectively blocked cell death and prolonged survival. Embryonic lethality of Ripk1K376R/K376R mice was prevented by the loss of TNFR1, or by simultaneous deletion of caspase-8 and RIPK3. Interestingly, elimination of the wild-type allele from adult Ripk1K376R/cko mice was tolerated. However, adult Ripk1K376R/cko mice were exquisitely sensitive to TNF-induced hypothermia and associated lethality. Absence of the K376 ubiquitination site diminished K11-linked, K63-linked, and linear ubiquitination of RIPK1, and promoted the assembly of death-inducing cellular complexes, suggesting that multiple ubiquitin linkages contribute to the stability of the RIPK1 signaling complex that stimulates NF-κB and MAPK activation. In contrast, mutating K115 did not affect RIPK1 ubiquitination or TNF stimulated NF-κB and MAPK signaling. Overall, our data indicate that selective impairment of RIPK1 ubiquitination can lower the threshold for RIPK1 activation by TNF resulting in cell death and embryonic lethality.

Protein Phosphatase 2A Inactivates Bcl2’s Antiapoptotic Function by Dephosphorylation and Up-Regulation of Bcl2-p53 Binding.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1436-1436
Author(s):  
Xingming Deng ◽  
Fengqin Gao ◽  
Tammy Flagg ◽  
W. Stratford May
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Apoptotic Cell ◽  
Protein Phosphatase 2A ◽  
Survival Function ◽  
Phosphorylation Site ◽  
Apoptotic Cell Death ◽  
Phosphatase 2A

Abstract DNA damage-induced p53/Bcl2 interaction at the outer mitochondrial membranes results in a Bcl2 conformational change and loss of its antiapoptotic function. Our data now indicate that either treatment of cells with the protein phosphatase 2A (PP2A) inhibitor, okadaic acid (10 nM), or specific disruption of PP2A activity by the expression of SV40 small tumor antigen enhances Bcl2 phosphorylation and suppresses the cisplatin-stimulated Bcl2-p53 interaction in association with prolonged cell survival. By contrast, C2-ceramide, a potent PP2A activator, reduces Bcl2 phosphorylation and increases Bcl2-p53 binding and promotes apoptotic cell death, suggesting that PP2A may function as a physiological regulator of Bcl2 by, at least in part, affecting its association with p53. Overexpression of the PP2A catalytic subunit (PP2A/C) suppresses Bcl2 phosphorylation in association with increased p53-Bcl2 binding and apoptotic cell death. By contrast, specific depletion of PP2A/C by RNA interference enhances Bcl2 phosphorylation, suppresses p53-Bcl2 interaction and prolongs cell survival. Purified PP2A can directly enhance the formation of the p53-Bcl2 complex in vitro in an okadaic acid-sensitive manner, supporting a direct mechanism. Importantly, PP2A directly interacts with Bcl2 at its BH4 domain which may function as the PP2A ‘docking site’ to potentially ‘bridge’ PP2A to the flexible loop domain which contains the physiological serine 70 phosphorylation site. Thus, PP2A may provide a double whammy to Bcl2’s survival function by both dephosphorylating and enhancing p53-Bcl2 binding. Therapeutically stimulating Bcl2 dephosphorylation and/or increasing Bcl2/p53 binding by activating PP2A may represent an efficient and novel antineoplastic approach.

scholarly journals Human Satellite III long non-coding RNA imparts survival benefits to cancer cells

2021 ◽  
Author(s):  
Manjima Chatterjee ◽  
Sonali Sengupta
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Heat Shock ◽  
Human Chromosome ◽  
Cell Survival ◽  
Cancer Cells ◽  
Survival Function ◽  
Human Cancers ◽  
Satellite Rnas ◽  
Non Coding Rnas

ABSTRACTLong non-coding RNAs are heterogeneous group of transcripts that lack coding potential and have crucial roles in gene regulations. Recent days have seen an increasing association of non-coding RNAs with human diseases, especially cancers. Satellite III (SatIII) lncRNAs are transcribed from pericentromeric heterochromatic region of the human chromosome. Though transcriptionally silent in normal conditions, SatIII is actively transcribed under condition of stress, mainly heat shock. SatII repeat, another component of pericentromeric region of human chromosome, has been associated with wide variety of epithelial cancer. Overexpression of Satellite RNAs induces breast cancer in mice. Though much is known about Satellite RNAs, which includes alpha satellites and SatII repeats, however little is known about SatIII in human cancers. Hence we directed our study to understand the role of human Satellite III repeats in cancerous conditions. In the present study, we show that colon and breast cancer cells transcribe SatIII independent of heat shock, in an HSF1-independent manner. Our study also reveals that, overexpression of SatIII RNA favours cancer cell survival by overriding chemo drug-induced cell death. Knockdown of SatIII sensitizes cells towards chemotherapeutic drugs. SatIII transcript knockdown restores the expression of p53 protein, which in turn facilitates cell death. Heat shock however helps SatIII to continue with its pro-cell survival function. Our results, therefore suggest SatIII to be an important regulator of human cancers. Induction of SatIII is not only a response to the oncogenic stress but also facilitates cancer progression by a distinct pathway that is different from heat stress pathway.

scholarly journals Necroptosis in Pulmonary Diseases: A New Therapeutic Target

2021 ◽  
Vol 12 ◽  
Author(s):  
Lingling Wang ◽  
Ling Zhou ◽  
Yuhao Zhou ◽  
Lu Liu ◽  
Weiling Jiang ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membranes ◽  
Inflammatory Responses ◽  
Neurological Diseases ◽  
Kinase Domain ◽  
The Body ◽  
Interacting Protein ◽  
Membrane Rupture ◽  
Regulated Cell Death ◽  
Scientific Attention

In the past decades, apoptosis has been the most well-studied regulated cell death (RCD) that has essential functions in tissue homeostasis throughout life. However, a novel form of RCD called necroptosis, which requires receptor-interacting protein kinase-3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), has recently been receiving increasing scientific attention. The phosphorylation of RIPK3 enables the recruitment and phosphorylation of MLKL, which oligomerizes and translocates to the plasma membranes, ultimately leading to plasma membrane rupture and cell death. Although apoptosis elicits no inflammatory responses, necroptosis triggers inflammation or causes an innate immune response to protect the body through the release of damage-associated molecular patterns (DAMPs). Increasing evidence now suggests that necroptosis is implicated in the pathogenesis of several human diseases such as systemic inflammation, respiratory diseases, cardiovascular diseases, neurodegenerative diseases, neurological diseases, and cancer. This review summarizes the emerging insights of necroptosis and its contribution toward the pathogenesis of lung diseases.

scholarly journals Genome-wide CRISPR-Cas9 screen reveals the importance of the heparan sulfate pathway and the conserved oligomeric golgi complex for synthetic dsRNA uptake and Sindbis virus infection

2020 ◽  
Author(s):  
Olivier Petitjean ◽  
Erika Girardi ◽  
Richard Patryk Ngondo ◽  
Vladimir Lupashin ◽  
Sébastien Pfeffer
Keyword(s):  
Cell Death ◽  
Heparan Sulfate ◽  
Cell Survival ◽  
Sindbis Virus ◽  
Human Cells ◽  
Innate Immune ◽  
Genome Wide ◽  
A Genome ◽  
Conserved Oligomeric Golgi Complex ◽  
Conserved Oligomeric Golgi

AbstractDouble stranded RNA (dsRNA) is the hallmark of many viral infections. dsRNA is produced either by RNA viruses during replication or by DNA viruses upon convergent transcription. Synthetic dsRNA is also able to mimic viral-induced activation of innate immune response and cell death. In this study, we employed a genome-wide CRISPR-Cas9 loss of function screen based on cell survival in order to identify genes implicated in the host response to dsRNA. By challenging HCT116 human cells with either synthetic dsRNA or Sindbis virus (SINV), we identified the heparan sulfate (HS) pathway as a crucial factor for dsRNA entry and we validated SINV dependency on HS. Interestingly, we uncovered a novel role for COG4, a component of the Conserved Oligomeric Golgi (COG) complex, as a factor involved in cell survival to both dsRNA and SINV in human cells. We showed that COG4 knock-out led to a decrease of extracellular HS, specifically affected dsRNA transfection efficiency and reduced viral production, explaining the increased cell survival of these mutants.ImportanceWhen facing a viral infection, the organism has to put in place a number of defense mechanisms in order to clear the pathogen from the cell. At the early phase of this preparation for fighting against the invader, the innate immune response is triggered by the sensing of danger signals. Among those molecular cues, double-stranded (dsRNA) is a very potent inducer of different reactions at the cellular level that can ultimately lead to cell death. Using a genome-wide screening approach, we set to identify genes involved in dsRNA entry, sensing and apoptosis induction in human cells. This allowed us to determine that the heparan sulfate pathway and the Conserved Oligomeric Golgi complex are key determinants allowing entry of both dsRNA and viral nucleic acid leading to cell death.

scholarly journals Genome-Wide CRISPR-Cas9 Screen Reveals the Importance of the Heparan Sulfate Pathway and the Conserved Oligomeric Golgi Complex for Synthetic Double-Stranded RNA Uptake and Sindbis Virus Infection

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Olivier Petitjean ◽  
Erika Girardi ◽  
Richard Patryk Ngondo ◽  
Vladimir Lupashin ◽  
Sébastien Pfeffer
Keyword(s):  
Cell Death ◽  
Heparan Sulfate ◽  
Cell Survival ◽  
Sindbis Virus ◽  
Human Cells ◽  
Double Stranded Rna ◽  
Genome Wide ◽  
A Genome ◽  
Conserved Oligomeric Golgi Complex ◽  
Conserved Oligomeric Golgi

ABSTRACT Double-stranded RNA (dsRNA) is the hallmark of many viral infections. dsRNA is produced either by RNA viruses during replication or by DNA viruses upon convergent transcription. Synthetic dsRNA is also able to mimic viral-induced activation of innate immune response and cell death. In this study, we employed a genome-wide CRISPR-Cas9 loss-of-function screen based on cell survival in order to identify genes implicated in the host response to dsRNA. By challenging HCT116 human cells with either synthetic dsRNA or Sindbis virus (SINV), we identified the heparan sulfate (HS) pathway as a crucial factor for dsRNA entry, and we validated SINV dependency on HS. Interestingly, we uncovered a novel role for COG4, a component of the conserved oligomeric Golgi (COG) complex, as a factor involved in cell survival to both dsRNA and SINV in human cells. We showed that COG4 knockout led to a decrease of extracellular HS that specifically affected dsRNA transfection efficiency and reduced viral production, which explains the increased cell survival of these mutants. IMPORTANCE When facing a viral infection, the organism has to put in place a number of defense mechanisms in order to clear the pathogen from the cell. At the early phase of this preparation for fighting against the invader, the innate immune response is triggered by the sensing of danger signals. Among those molecular cues, double-stranded RNA (dsRNA) is a very potent inducer of different reactions at the cellular level that can ultimately lead to cell death. Using a genome-wide screening approach, we set to identify genes involved in dsRNA entry, sensing, and apoptosis induction in human cells. This allowed us to determine that the heparan sulfate pathway and the conserved oligomeric Golgi complex are key determinants allowing entry of both dsRNA and viral nucleic acid leading to cell death.

scholarly journals Post-translational control of RIPK3 and MLKL mediated necroptotic cell death

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 1297 ◽  
Author(s):  
James M. Murphy ◽  
James E. Vince
Keyword(s):  
Cell Death ◽  
Translational Control ◽  
Kinase Domain ◽  
Current Evidence ◽  
Deubiquitinating Enzymes ◽  
Critical Function ◽  
Interacting Protein ◽  
Mixed Lineage Kinase ◽  
Microbial Infections ◽  
Cell Death Mechanisms

Several programmed lytic and necrotic-like cell death mechanisms have now been uncovered, including the recently described receptor interacting protein kinase-3 (RIPK3)-mixed lineage kinase domain-like (MLKL)-dependent necroptosis pathway. Genetic experiments have shown that programmed necrosis, including necroptosis, can play a pivotal role in regulating host-resistance against microbial infections. Alternatively, excess or unwarranted necroptosis may be pathological in autoimmune and autoinflammatory diseases. This review highlights the recent advances in our understanding of the post-translational control of RIPK3-MLKL necroptotic signaling. We discuss the critical function of phosphorylation in the execution of necroptosis, and highlight the emerging regulatory roles for several ubiquitin ligases and deubiquitinating enzymes. Finally, based on current evidence, we discuss the potential mechanisms by which the essential, and possibly terminal, necroptotic effector, MLKL, triggers the disruption of cellular membranes to cause cell lysis.

Inflammatory outcomes of apoptosis, necrosis and necroptosis

2014 ◽  
Vol 395 (10) ◽  
pp. 1163-1171 ◽  
Author(s):  
Pavel Davidovich ◽  
Conor J. Kearney ◽  
Seamus J. Martin
Keyword(s):  
Cell Death ◽  
Inflammatory Responses ◽  
Tissue Injury ◽  
Necrotic Cell Death ◽  
Caspase Activation ◽  
Microbial Infection ◽  
Necrotic Cell ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
Pro Inflammatory Cytokines

Abstract Microbial infection and tissue injury are well established as the two major drivers of inflammation. However, although it is widely accepted that necrotic cell death can trigger or potentiate inflammation, precisely how this is achieved still remains relatively obscure. Certain molecules, which have been dubbed ‘damage-associated molecular patterns’ (DAMPs) or alarmins, are thought to promote inflammation upon release from necrotic cells. However, the precise nature and relative potency of DAMPs, compared to conventional pro-inflammatory cytokines or pathogen-associated molecular patterns (PAMPs), remains unclear. How different modes of cell death impact on the immune system also requires further clarification. Apoptosis has long been regarded as a non-inflammatory or even anti-inflammatory mode of cell death, but recent studies suggest that this is not always the case. Necroptosis is a programmed form of necrosis that is engaged under certain conditions when caspase activation is blocked. Necroptosis is also regarded as a highly pro-inflammatory mode of cell death but there has been little explicit examination of this issue. Here we discuss the inflammatory implications of necrosis, necroptosis and apoptosis and some of the unresolved questions concerning how dead cells influence inflammatory responses.

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