5 research outputs found
Implication of the NLRP3 inflammasome in the unconventional secretion of the FADD protein
FADD (FAS-Associated Death Domain) est la protĂ©ine adaptatrice clĂ© de l'apoptose via les rĂ©cepteurs de mort. Elle est Ă©galement impliquĂ©e dans d'autres types de mort cellulaire, mais aussi dans des mĂ©canismes de survie, la prolifĂ©ration et le cycle cellulaire. C'est donc une protĂ©ine rĂ©gulatrice de la vie et de la mort et un changement de son expression peut avoir de graves consĂ©quences physiopathologiques. Par exemple, l'Ă©quipe a montrĂ© que l'expression de la protĂ©ine FADD pouvait ĂȘtre perdue dans des biopsies de cancer du poumon et que cette perte Ă©tait corrĂ©lĂ©e Ă la sĂ©crĂ©tion de la protĂ©ine FADD dans le milieu extracellulaire. Cette sĂ©crĂ©tion Ă©tant associĂ©e Ă l'agressivitĂ© et au dĂ©veloppement tumoral, il apparaĂźt important de comprendre quels sont les mĂ©canismes molĂ©culaires impliquĂ©s dans ce processus. En plus de son rĂŽle dans la cancĂ©rogenĂšse, FADD est aussi impliquĂ©e dans l'immunitĂ© innĂ©e et l'inflammation. En effet, FADD participe Ă l'activation de l'inflammasome NLRP3 via les trois voies dĂ©crites : canonique, non canonique et alternative. L'inflammasome NLRP3 est un gros complexe multiprotĂ©ique composĂ© de la protĂ©ine senseur NLRP3, de la protĂ©ine adaptatrice ASC et de la pro-caspase-1, qui s'assemble en rĂ©ponse Ă des signaux de stress ou de danger. Il conduit Ă l'activation de rĂ©ponses inflammatoires mĂ©diĂ©es par la caspase-1, telles que le clivage et la sĂ©crĂ©tion non conventionnelle de la cytokine pro-inflammatoire interleukine-1 beta (IL-1b). L'inflammasome NLRP3 a Ă©tĂ© largement impliquĂ© dans le dĂ©veloppement et la progression de plusieurs rhumatismes inflammatoires chroniques comme la goutte et, plus rĂ©cemment, la polyarthrite rhumatoĂŻde (PR). Des protĂ©ines participant au complexe NRLP3 telles que ASC et la caspase-1 peuvent ĂȘtre co-sĂ©crĂ©tĂ©es avec l'IL-1b, sous la rĂ©gulation de l'inflammasome NLRP3. Puisque FADD participe Ă son activation, les objectifs de ma thĂšse Ă©taient d'Ă©tudier l'implication de l'inflammasome NLRP3 dans la sĂ©crĂ©tion de FADD ; puis de caractĂ©riser la ou les voie(s) de sĂ©crĂ©tion de la protĂ©ine FADD ; et enfin de dĂ©terminer si cette sĂ©crĂ©tion pouvait ĂȘtre retrouvĂ©e in vivo dans des pathologies rhumatismales. Pour cette Ă©tude, nous avons utilisĂ© la lignĂ©e monocytaire humaine THP-1, modĂšle classique d'Ă©tude de l'inflammasome NLRP3. Nous avons montrĂ© que la protĂ©ine FADD est sĂ©crĂ©tĂ©e suite Ă la stimulation de l'inflammasome NLPR3 par des activateurs des voies canonique (nigĂ©ricine, ATP, cristaux) et non canonique (Escherichia coli entĂ©ropathogĂšne) mais pas alternative (lipopolysaccharide). Cette sĂ©crĂ©tion de FADD requiĂšre un efflux de potassium. A l'aide de la technique CRISPR/Cas9, nous avons montrĂ© que la sĂ©crĂ©tion nĂ©cessite Ă©galement les protĂ©ines NLRP3, ASC et caspase-1. De plus, nous avons identifiĂ© la protĂ©ine FADD comme une protĂ©ine sĂ©crĂ©tĂ©e de façon non conventionnelle dans des microvĂ©sicules dĂ©rivĂ©es de la membrane plasmique, mais pas dans des exosomes. Ces vĂ©sicules contiennent Ă©galement les protĂ©ines IL-1b, NLRP3, ASC et caspase-1. Ces rĂ©sultats ont Ă©tĂ© replacĂ©s dans un contexte physiopathologique puisque des monocytes sanguins de donneurs sains sĂ©crĂštent Ă©galement FADD suite Ă l'activation canonique de l'inflammasome NLRP3. La sĂ©crĂ©tion par des monocytes de patients atteints de PR est augmentĂ©e et de fortes concentrations de protĂ©ine FADD sont dĂ©tectĂ©es dans le sĂ©rum de patients atteints de PR (cohorte ESPOIR) mais pas de donneurs sains. Dans cette cohorte, la concentration de FADD sĂ©rique est corrĂ©lĂ©e Ă l'Ă©volution de l'Ă©rosion osseuse articulaire des patients. De plus, de fortes concentrations de protĂ©ine FADD sont Ă©galement dĂ©tectĂ©es localement dans le liquide articulaire de patients atteints de PR et de goutte, mais pas d'arthrose (pathologie peu inflammatoire). Ces concentrations sont positivement corrĂ©lĂ©es Ă l'Ă©tat inflammatoire de l'articulation. Ainsi, la protĂ©ine FADD sĂ©crĂ©tĂ©e serait un nouveau marqueur de l'inflammation dans ces pathologies rhumatismales.FADD (FAS-Associated Death Domain) is a key adaptor protein of death receptor-mediated apoptosis. FADD is also implicated in other types of cell death, but also in survival mechanisms, proliferation and cell cycle progression. Therefore, FADD is a regulator of life and death and a change of its expression can have dramatic physiopathological consequences. For instance, the team has showed that FADD protein expression can be lost in lung cancer biopsies. This loss is correlated with FADD protein secretion in the extracellular compartment. Since this secretion is associated with tumor development and aggressiveness, it is important to decipher the molecular mechanisms behind this process. Besides its role in tumorigenesis, FADD is also involved in innate immunity and inflammation. Indeed, FADD participates to the canonical, non-canonical and alternative pathways of activation of the NLRP3 inflammasome. This inflammasome is a large multiprotein complex composed of the sensor protein NLRP3, the adaptor protein ASC and the pro-caspase-1. This complex assembles in response to stress or danger signals. This leads to the activation of inflammatory responses mediated by caspase-1, such as cleavage and unconventional secretion of the pro-inflammatory cytokine interleukin-1 beta (IL-1b). The NLRP3 inflammasome is largely implicated in the development and progression of several chronic inflammatory rheumatisms like gout and, more recently, rheumatoid arthritis (RA). Proteins of the NLRP3 complex such as ASC and caspase-1 can be co-secreted with IL-1b following the NRLP3 inflammasome activation. Since FADD participates to the complex, the aims of my thesis were to study the involvement of the NLRP3 inflammasome in the FADD secretion process; to characterize the secretion pathway(s) implicated; and to determine if this secretion can occur in vivo during the course of chronic inflammatory rheumatisms. For this study, we used the THP-1 human monocytic cell line that is an established model for inflammasome studies. We showed that FADD protein is secreted following cell stimulation with activators of the canonical (nigericin, ATP, crystals) and non-canonical (enteropathogenic Escherichia coli) but not alternative (lipopolysaccharide) NLRP3 inflammasome pathways. Furthermore, this FADD secretion process requires potassium efflux. Using CRIPSR/Cas9 technology, we showed that FADD secretion also requires NLRP3, ASC and caspase-1 proteins. Moreover, we have identified FADD as a new member of the unconventionally secreted protein family. Indeed, FADD is secreted in plasma membrane-derived microvesicles but not in exosomes. These microvesicles also contain IL-1b, NLRP3, ASC and caspase-1 proteins. In a more physiopathological context, we showed that blood-derived primary monocytes from healthy donors secrete FADD following canonical NLRP3 inflammasome activation, and this secretion is enhanced using monocytes from RA-suffering patients. In addition, high concentration of FADD protein is detected in the sera from RA patients (ESPOIR cohort) as compared to sera from healthy donors. In this cohort, sera concentration of FADD is correlated with patient's joint bone erosion progression. Moreover, high concentration of FADD is also detected locally in the synovial fluid from RA-, gout- but not osteoarthritis (a poorly inflammatory disease)-suffering patients. This concentration is positively correlated with the inflammatory status of the joint. Thus, secreted FADD protein can be a new marker of joint inflammation in these pathologies
FADD at the Crossroads between Cancer and Inflammation
International audienceInitially described as an adaptor molecule for death receptor (DR)-mediated apoptosis, Fas-associated death domain (FADD) was later implicated in nonapoptotic cellular processes. During the last decade, FADD has been shown to participate and regulate most of the signalosome complexes, including necrosome, FADDosome, innateosome, and inflammasome. Given the role of these signaling complexes, FADD has emerged as a new actor in innate immunity, inflammation, and cancer development. Concomitant to these new roles, a surprising number of mechanisms deemed to regulate FADD functions have been identified, including post-translational modifications of FADD protein and FADD secretion. This review focuses on recent knowledge of the biological roles of FADD, a pleiotropic molecule having multiple partners, and its impact in cancer, innate immunity, and inflammation
InnenrĂŒcktitelbild: Small Molecule Inhibitors of InterferonâInduced JAKâSTAT Signalling (Angew. Chem. 32/2022)
International audienc
Inactivation of cytidine triphosphate synthase 1 prevents fatal auto-immunity in mice
Abstract De novo synthesis of the pyrimidine, cytidine triphosphate (CTP), is crucial for DNA/RNA metabolism and depends on the CTP synthetases, CTPS1 and â2. Partial CTPS1 deficiency in humans has previously been shown to lead to immunodeficiency, with impaired expansion of T and B cells. Here, we examine the effects of conditional and inducible inactivation of Ctps1 and/or Ctps2 on mouse embryonic development and immunity. We report that deletion of Ctps1, but not Ctps2, is embryonic-lethal. Tissue and cells with high proliferation and renewal rates, such as intestinal epithelium, erythroid and thymic lineages, activated B and T lymphocytes, and memory T cells strongly rely on CTPS1 for their maintenance and growth. However, both CTPS1 and CTPS2 are required for T cell proliferation following TCR stimulation. Deletion of Ctps1 in T cells or treatment with a CTPS1 inhibitor rescued Foxp3-deficient mice from fatal systemic autoimmunity and reduced the severity of experimental autoimmune encephalomyelitis. These findings support that CTPS1 may represent a target for immune suppression