RESUMO
RIPK1 is involved in signaling from TNF and TLR family receptors. After receptor ligation, RIPK1 not only modulates activation of both canonical and NIK-dependent NF-κB, but also regulates caspase-8 activation and cell death. Although overexpression of RIPK1 can cause caspase-8-dependent cell death, when RIPK1(-/-) cells are exposed to TNF and low doses of cycloheximide, they die more readily than wild-type cells, indicating RIPK1 has pro-survival as well as pro-apoptotic activities. To determine how RIPK1 promotes cell survival, we compared wild-type and RIPK1(-/-) cells treated with TNF. Although TRAF2 levels remained constant in TNF-treated wild-type cells, TNF stimulation of RIPK1(-/-) cells caused TRAF2 and cIAP1 to be rapidly degraded by the proteasome, which led to an increase in NIK levels. This resulted in processing of p100 NF-κB2 to p52, a decrease in levels of cFLIP(L), and activation of caspase-8, culminating in cell death. Therefore, the pro-survival effect of RIPK1 is mediated by stabilization of TRAF2 and cIAP1.
Assuntos
Caspase 8/metabolismo , Proteínas Inibidoras de Apoptose/metabolismo , NF-kappa B/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Fator 2 Associado a Receptor de TNF/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Caspase 8/genética , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Cicloeximida/farmacologia , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Proteínas Inibidoras de Apoptose/genética , Camundongos , Camundongos Knockout , NF-kappa B/genética , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Estabilidade Proteica , Inibidores da Síntese de Proteínas/farmacologia , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Fator 2 Associado a Receptor de TNF/genética , Fator de Necrose Tumoral alfa/farmacologia , Quinase Induzida por NF-kappaBRESUMO
The Inhibitor of apoptosis (IAP) proteins are key negative regulators of cell death, whose amplification has been correlated with tumor progression. Due to the presence of a RING domain, IAP proteins are classed as ubiquitin ligases and regulate cell survival by orchestrating a variety of ubiquitin modifications. Ubiquitin protein modification is fundamental in cell signaling and different ubiquitin modifications may label proteins for destruction, relocalization or provide a recruitment platform for ubiquitin binding proteins. Ubiquitin performs a myriad of different functions because it can be conjugated to a large range of target proteins through numerous different types of ubiquitin linkages. Despite the fact that ubiquitin is extremely versatile, the E3s such as the IAPs provide an important level of control due to their specificity for certain substrates. Several recent reviews have discussed the role of IAPs in regulating immune signaling so we have therefore focused our review on the interplay between IAPs and ubiquitin and discussed the importance of this relationship for the regulation of themselves, specific substrates and various cell death and survival signaling pathways.
Assuntos
Proteínas Inibidoras de Apoptose/fisiologia , Processamento de Proteína Pós-Traducional , Ubiquitina-Proteína Ligases/fisiologia , Animais , Apoptose , Sobrevivência Celular , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Ubiquitina-Proteína Ligases/metabolismo , UbiquitinaçãoRESUMO
The current literature acknowledges that occupational exposures can adversely affect mental health. This review seeks to elucidate the current understanding of the effect of agrichemical exposure on mental health in the agricultural sector, including low-dose, chronic pesticide exposure. This scoping review adopted a snowballing and saturation approach. The review highlights inconsistencies in linking poor mental health and pesticide use. While some studies specifically showed that both high- and low-dose pesticide exposure were associated with poor mental health, consistent and rigorous research methods are lacking. The review also proposes terms to delineate exposure types described in the literature. The review outcomes direct efforts to protect the health, wellbeing and safety of farming communities across the globe.
Assuntos
Agroquímicos/toxicidade , Fazendeiros , Transtornos Mentais/induzido quimicamente , Exposição Ocupacional/efeitos adversos , Praguicidas/toxicidade , Agricultura , HumanosRESUMO
Peptido-mimetic inhibitor of apoptosis protein (IAP) antagonists (Smac mimetics (SMs)) can kill tumour cells by depleting endogenous IAPs and thereby inducing tumour necrosis factor (TNF) production. We found that interferon-γ (IFNγ) synergises with SMs to kill cancer cells independently of TNF- and other cell death receptor signalling pathways. Surprisingly, CRISPR/Cas9 HT29 cells doubly deficient for caspase-8 and the necroptotic pathway mediators RIPK3 or MLKL were still sensitive to IFNγ/SM-induced killing. Triple CRISPR/Cas9-knockout HT29 cells lacking caspase-10 in addition to caspase-8 and RIPK3 or MLKL were resistant to IFNγ/SM killing. Caspase-8 and RIPK1 deficiency was, however, sufficient to protect cells from IFNγ/SM-induced cell death, implying a role for RIPK1 in the activation of caspase-10. These data show that RIPK1 and caspase-10 mediate cell death in HT29 cells when caspase-8-mediated apoptosis and necroptosis are blocked and help to clarify how SMs operate as chemotherapeutic agents.
Assuntos
Apoptose/efeitos dos fármacos , Caspase 10/metabolismo , Proteínas Inibidoras de Apoptose/metabolismo , Interferon gama/farmacologia , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Animais , Sistemas CRISPR-Cas/genética , Caspase 10/química , Caspase 10/genética , Caspase 8/química , Caspase 8/genética , Caspase 8/metabolismo , Inibidores de Caspase/farmacologia , Linhagem Celular , Citocina TWEAK/farmacologia , Sinergismo Farmacológico , Células HT29 , Humanos , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Interferon gama/genética , Interferon gama/metabolismo , Camundongos , Camundongos Knockout , Ácidos Pentanoicos/farmacologia , Proteínas Quinases/deficiência , Proteínas Quinases/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Receptores Tipo I de Fatores de Necrose Tumoral/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/farmacologiaRESUMO
RIPK3 and its substrate MLKL are essential for necroptosis, a lytic cell death proposed to cause inflammation via the release of intracellular molecules. Whether and how RIPK3 might drive inflammation in a manner independent of MLKL and cell lysis remains unclear. Here we show that following LPS treatment, or LPS-induced necroptosis, the TLR adaptor protein TRIF and inhibitor of apoptosis proteins (IAPs: X-linked IAP, cellular IAP1 and IAP2) regulate RIPK3 and MLKL ubiquitylation. Hence, when IAPs are absent, LPS triggers RIPK3 to activate caspase-8, promoting apoptosis and NLRP3-caspase-1 activation, independent of RIPK3 kinase activity and MLKL. In contrast, in the absence of both IAPs and caspase-8, RIPK3 kinase activity and MLKL are essential for TLR-induced NLRP3 activation. Consistent with in vitro experiments, interleukin-1 (IL-1)-dependent autoantibody-mediated arthritis is exacerbated in mice lacking IAPs, and is reduced by deletion of RIPK3, but not MLKL. Therefore RIPK3 can promote NLRP3 inflammasome and IL-1ß inflammatory responses independent of MLKL and necroptotic cell death.
Assuntos
Células da Medula Óssea/citologia , Proteínas de Transporte/metabolismo , Inflamassomos/metabolismo , Proteínas Quinases/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Animais , Apoptose , Autoanticorpos/química , Caspase 8/metabolismo , Ativação Enzimática , Feminino , Inflamação , Proteínas Inibidoras de Apoptose/metabolismo , Interleucina-1beta/metabolismo , Lipopolissacarídeos/química , Fígado/embriologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína 3 que Contém Domínio de Pirina da Família NLR , Necrose , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismoRESUMO
Necroptosis describes a pro-inflammatory form of cell death governed by the kinases RIP1 and RIP3. Necroptosis can occur following stimulation of the DNA receptor, DAI, or activation of death receptor, Toll-like receptor, T-cell antigen receptor, or interferon receptor signaling. Analysis of RIP3 deficient mice has implicated necroptosis in several inflammatory-driven diseases, including atherosclerosis, alcoholic liver disease and retinal degeneration. Although studies have demonstrated that mixed lineage kinase domain-like (MLKL) is the only substrate of RIP3 kinase that is essential for necroptotic death, the molecular determinants acting downstream of MLKL remain ambiguous. In addition, RIP3 can signal necroptosis independent of RIP1, may induce apoptosis, and can directly promote pro-inflammatory cytokine production. Therefore it will be important to determine if non-necroptotic RIP3 signaling influences RIP3 dependent pathologies.
Assuntos
Apoptose/imunologia , Regulação para Baixo/imunologia , Proteína Serina-Treonina Quinases de Interação com Receptores/fisiologia , Transdução de Sinais/imunologia , Animais , Apoptose/genética , Caspase 8/fisiologia , Morte Celular/genética , Morte Celular/imunologia , Regulação para Baixo/genética , Proteína Ligante Fas/fisiologia , Humanos , Células Jurkat , Necrose/genética , Necrose/imunologia , Necrose/patologia , Proteínas Quinases/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/fisiologia , Transdução de Sinais/genética , Especificidade por Substrato/genética , Especificidade por Substrato/imunologiaRESUMO
Birinapant (1) is a second-generation bivalent antagonist of IAP proteins that is currently undergoing clinical development for the treatment of cancer. Using a range of assays that evaluated cIAP1 stability and oligomeric state, we demonstrated that 1 stabilized the cIAP1-BUCR (BIR3-UBA-CARD-RING) dimer and promoted autoubiquitylation of cIAP1 in vitro. Smac-mimetic 1-induced loss of cIAPs correlated with inhibition of TNF-mediated NF-κB activation, caspase activation, and tumor cell killing. Many first-generation Smac-mimetics such as compound A (2) were poorly tolerated. Notably, animals that lack functional cIAP1, cIAP2, and XIAP are not viable, and 2 mimicked features of triple IAP knockout cells in vitro. The improved tolerability of 1 was associated with (i) decreased potency against cIAP2 and affinity for XIAP BIR3 and (ii) decreased ability to inhibit XIAP-dependent signaling pathways. The P2' position of 1 was critical to this differential activity, and this improved tolerability has allowed 1 to proceed into clinical studies.
Assuntos
Antineoplásicos/farmacologia , Proteínas de Transporte/química , Dipeptídeos/farmacologia , Neoplasias Hematológicas/tratamento farmacológico , Indóis/farmacologia , Proteínas Mitocondriais/química , Mimetismo Molecular , Neoplasias Experimentais/tratamento farmacológico , Animais , Antineoplásicos/uso terapêutico , Proteínas Reguladoras de Apoptose , Dipeptídeos/uso terapêutico , Descoberta de Drogas , Indóis/uso terapêutico , Camundongos , Modelos MolecularesRESUMO
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known as a "death ligand"-a member of the TNF superfamily that binds to receptors bearing death domains. As well as causing apoptosis of certain types of tumor cells, TRAIL can activate both NF-kappaB and JNK signalling pathways. To determine the role of TGF-beta-Activated Kinase-1 (TAK1) in TRAIL signalling, we analyzed the effects of adding TRAIL to mouse embryonic fibroblasts (MEFs) derived from TAK1 conditional knockout mice. TAK1-/- MEFs were significantly more sensitive to killing by TRAIL than wild-type MEFs, and failed to activate NF-kappaB or JNK. Overexpression of IKK2-EE, a constitutive activator of NF-kappaB, protected TAK1-/- MEFs against TRAIL killing, suggesting that TAK1 activation of NF-kappaB is critical for the viability of cells treated with TRAIL. Consistent with this model, TRAIL failed to induce the survival genes cIAP2 and cFlipL in the absence of TAK1, whereas activation of NF-kappaB by IKK2-EE restored the levels of both proteins. Moreover, ectopic expression of cFlipL, but not cIAP2, in TAK1-/- MEFs strongly inhibited TRAIL-induced cell death. These results indicate that cells that survive TRAIL treatment may do so by activation of a TAK1-NF-kappaB pathway that drives expression of cFlipL, and suggest that TAK1 may be a good target for overcoming TRAIL resistance.
Assuntos
Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/biossíntese , Sobrevivência Celular/fisiologia , MAP Quinase Quinase Quinases/fisiologia , NF-kappa B/fisiologia , Ligante Indutor de Apoptose Relacionado a TNF/administração & dosagem , Animais , Sequência de Bases , Caspase 8/metabolismo , Células Cultivadas , Primers do DNA , Fibroblastos/citologia , Camundongos , Camundongos Knockout , Transdução de SinaisRESUMO
XIAP prevents apoptosis by binding to and inhibiting caspases, and this inhibition can be relieved by IAP antagonists, such as Smac/DIABLO. IAP antagonist compounds (IACs) have therefore been designed to inhibit XIAP to kill tumor cells. Because XIAP inhibits postmitochondrial caspases, caspase 8 inhibitors should not block killing by IACs. Instead, we show that apoptosis caused by an IAC is blocked by the caspase 8 inhibitor crmA and that IAP antagonists activate NF-kappaB signaling via inhibtion of cIAP1. In sensitive tumor lines, IAP antagonist induced NF-kappaB-stimulated production of TNFalpha that killed cells in an autocrine fashion. Inhibition of NF-kappaB reduced TNFalpha production, and blocking NF-kappaB activation or TNFalpha allowed tumor cells to survive IAC-induced apoptosis. Cells treated with an IAC, or those in which cIAP1 was deleted, became sensitive to apoptosis induced by exogenous TNFalpha, suggesting novel uses of these compounds in treating cancer.