RESUMO
Inflammasome activation is critical for host defenses against various microbial infections. Activation of the NLRC4 inflammasome requires detection of flagellin or type III secretion system (T3SS) components by NLR family apoptosis inhibitory proteins (NAIPs); yet how this pathway is regulated is unknown. Here, we found that interferon regulatory factor 8 (IRF8) is required for optimal activation of the NLRC4 inflammasome in bone-marrow-derived macrophages infected with Salmonella Typhimurium, Burkholderia thailandensis, or Pseudomonas aeruginosa but is dispensable for activation of the canonical and non-canonical NLRP3, AIM2, and Pyrin inflammasomes. IRF8 governs the transcription of Naips to allow detection of flagellin or T3SS proteins to mediate NLRC4 inflammasome activation. Furthermore, we found that IRF8 confers protection against bacterial infection in vivo, owing to its role in inflammasome-dependent cytokine production and pyroptosis. Altogether, our findings suggest that IRF8 is a critical regulator of NAIPs and NLRC4 inflammasome activation for defense against bacterial infection.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Inflamassomos/metabolismo , Fatores Reguladores de Interferon/metabolismo , Proteína Inibidora de Apoptose Neuronal/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas de Ligação ao Cálcio/genética , Células Cultivadas , Citocinas/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Flagelina/metabolismo , Fatores Reguladores de Interferon/antagonistas & inibidores , Fatores Reguladores de Interferon/genética , Macrófagos/citologia , Macrófagos/metabolismo , Macrófagos/microbiologia , Camundongos , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteína Inibidora de Apoptose Neuronal/genética , Regiões Promotoras Genéticas , Ligação Proteica , Pseudomonas aeruginosa/patogenicidade , Piroptose , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Salmonella typhimurium/patogenicidade , Transcrição GênicaRESUMO
Chronic recurrent multifocal osteomyelitis (CRMO) in humans can be modeled in Pstpip2cmo mice, which carry a missense mutation in the proline-serine-threonine phosphatase-interacting protein 2 (Pstpip2) gene. As cmo disease in mice, the experimental model analogous to human CRMO, is mediated specifically by IL-1ß and not by IL-1α, delineating the molecular pathways contributing to pathogenic IL-1ß production is crucial to developing targeted therapies. In particular, our earlier findings support redundant roles of NLR family pyrin domain-containing 3 (NLRP3) and caspase-1 with caspase-8 in instigating cmo However, the signaling components upstream of caspase-8 and pro-IL-1ß cleavage in Pstpip2cmo mice are not well-understood. Therefore, here we investigated the signaling pathways in these mice and discovered a central role of a nonreceptor tyrosine kinase, spleen tyrosine kinase (SYK), in mediating osteomyelitis. Using several mutant mouse strains, immunoblotting, and microcomputed tomography, we demonstrate that absent in melanoma 2 (AIM2), receptor-interacting serine/ threonine protein kinase 3 (RIPK3), and caspase recruitment domain-containing protein 9 (CARD9) are each dispensable for osteomyelitis induction in Pstpip2cmo mice, whereas genetic deletion of Syk completely abrogates the disease phenotype. We further show that SYK centrally mediates signaling upstream of caspase-1 and caspase-8 activation and principally up-regulates NF-κB and IL-1ß signaling in Pstpip2cmo mice, thereby inducing cmo These results provide a rationale for directly targeting SYK and its downstream signaling components in CRMO.
Assuntos
Caspase 8/metabolismo , Inflamassomos/metabolismo , Inflamação/patologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Osteomielite/patologia , Quinase Syk/metabolismo , Animais , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Proteínas de Ligação a DNA/metabolismo , Progressão da Doença , Inflamação/complicações , Inflamação/diagnóstico por imagem , Interleucina-1beta/metabolismo , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Osteomielite/complicações , Osteomielite/diagnóstico por imagem , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Transdução de SinaisRESUMO
Prior to initiating symptomatic malaria, a single Plasmodium sporozoite infects a hepatocyte and develops into thousands of merozoites, in part by scavenging host resources, likely delivered by vesicles. Here, we demonstrate that host microtubules (MTs) dynamically reorganize around the developing liver stage (LS) parasite to facilitate vesicular transport to the parasite. Using a genome-wide CRISPR-Cas9 screen, we identified host regulators of cytoskeleton organization, vesicle trafficking, and ER/Golgi stress that regulate LS development. Foci of γ-tubulin localized to the parasite periphery; depletion of centromere protein J (CENPJ), a novel regulator identified in the screen, exacerbated this re-localization and increased infection. We demonstrate that the Golgi acts as a non-centrosomal MT organizing center (ncMTOC) by positioning γ-tubulin and stimulating MT nucleation at parasite periphery. Together, these data support a model where the Plasmodium LS recruits host Golgi to form MT-mediated conduits along which host organelles are recruited to PVM and support parasite development.
Assuntos
Malária , Proteínas Associadas aos Microtúbulos , Microtúbulos , Sistemas CRISPR-Cas , Humanos , Fígado/metabolismo , Fígado/parasitologia , Malária/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Plasmodium/metabolismo , Tubulina (Proteína)/metabolismoRESUMO
There is a scarcity of pharmacological tools to interrogate protein kinase function in Plasmodium parasites, the causative agent of malaria. Among Plasmodium's protein kinases, those characterized as atypical represent attractive drug targets as they lack sequence similarity to human proteins. Here, we describe takinib as a small molecule to bind the atypical P. falciparum protein kinase 9 (PfPK9). PfPK9 phosphorylates the Plasmodium E2 ubiquitin-conjugating enzyme PfUBC13, which mediates K63-linkage-specific polyubiquitination. Takinib is a potent human TAK1 inhibitor, thus we developed the Plasmodium-selective takinib analog HS220. We demonstrate that takinib and HS220 decrease K63-linked ubiquitination in P. falciparum, suggesting PfPK9 inhibition in cells. Takinib and HS220 induce a unique phenotype where parasite size in hepatocytes increases, yet high compound concentrations decrease the number of parasites. Our studies highlight the role of PK9 in regulating parasite development and the potential of targeting Plasmodium kinases for malaria control.