Dataset Information

Microtubule-Mediated NLRP3 Inflammasome Activation Is Independent of Microtubule-Associated Innate Immune Factor GEF-H1 in Murine Macrophages.

ABSTRACT: Inflammasomes are intracellular multiple protein complexes that mount innate immune responses to tissue damage and invading pathogens. Their excessive activation is crucial in the development and pathogenesis of inflammatory disorders. Microtubules have been reported to provide the platform for mediating the assembly and activation of NLRP3 inflammasome. Recently, we have identified the microtubule-associated immune molecule guanine nucleotide exchange factor-H1 (GEF-H1) that is crucial in coupling microtubule dynamics to the initiation of microtubule-mediated immune responses. However, whether GEF-H1 also controls the activation of other immune receptors that require microtubules is still undefined. Here we employed GEF-H1-deficient mouse bone marrow-derived macrophages (BMDMs) to interrogate the impact of GEF-H1 on the activation of NLRP3 inflammasome. NLRP3 but not NLRC4 or AIM2 inflammasome-mediated IL-1? production was dependent on dynamic microtubule network in wild-type (WT) BMDMs. However, GEF-H1 deficiency did not affect NLRP3-driven IL-1? maturation and secretion in macrophages. Moreover, ?-tubulin acetylation and mitochondria aggregations were comparable between WT and GEF-H1-deficient BMDMs in response to NLRP3 inducers. Further, GEF-H1 was not required for NLRP3-mediated immune defense against Salmonella typhimurium infection. Collectively, these findings suggest that the microtubule-associated immune modulator GEF-H1 is dispensable for microtubule-mediated NLRP3 activation and host defense in mouse macrophages.

SUBMITTER: Lai HJ

PROVIDER: S-EPMC7072875 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Microtubule-Mediated NLRP3 Inflammasome Activation Is Independent of Microtubule-Associated Innate Immune Factor GEF-H1 in Murine Macrophages.

Lai Hsuan-Ju HJ Hsu Yi-Hsuan YH Lee Guan-Ying GY Chiang Hao-Sen HS

International journal of molecular sciences 20200214 4

Inflammasomes are intracellular multiple protein complexes that mount innate immune responses to tissue damage and invading pathogens. Their excessive activation is crucial in the development and pathogenesis of inflammatory disorders. Microtubules have been reported to provide the platform for mediating the assembly and activation of NLRP3 inflammasome. Recently, we have identified the microtubule-associated immune molecule guanine nucleotide exchange factor-H1 (GEF-H1) that is crucial in coupl ...[more]

PMID: 32075101

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Project description:BackgroundNeospora caninum is an intracellular parasite that causes significant economic losses in cattle industry. Understanding the host resistance mechanisms in the innate immune response to neosporosis could facilitate the exploration of approaches for controlling N. caninum infection. The NLR inflammasome is a multiprotein platform in the cell cytoplasm and plays critical roles in the host response against microbes.MethodsNeospora caninum-infected wild-type (WT) macrophages and Nlrp3 -/- macrophages, and inhibitory approaches were used to investigate inflammasome activation and its role in N. caninum infection. Inflammasome RT Profiler PCR Arrays were used to identify the primary genes involved in N. caninum infection. The expression of the sensor protein NLRP3, processing of caspase-1, secretion of IL-1β and cell death were detected. Neospora caninum replication in macrophages was also assessed.ResultsMany NLR molecules participated in the recognition of N. caninum, especially the sensor protein NLRP3, and further study revealed that the NLRP3 distribution became punctate in the cell cytoplasm, which facilitated inflammasome activation. Inflammasome activation-mediated caspase-1 processing and IL-1β cleavage in response to N. caninum infection were observed and were correlated with the time of infection and number of infecting parasites. LDH-related cell death was also observed, and this death was regarded as beneficial for the clearance of N. caninum. Treatment of N. caninum-infected macrophages with caspase-1, pan-caspase and NLRP3 inhibitors led to the impaired release of active IL-1β and a failure to restrict parasite replication. And Neospora caninum infected peritoneal macrophages from Nlrp3-deficient mice displayed greatly decreased release of active IL-1β and the failure of caspase-1 cleavage.ConclusionsThe NLRP3 inflammasome can be activated in N. caninum-infected macrophages, and plays a protective role in the host response to control N. caninum.

Project description:Microtubules play critical roles in regulating the activation of NLRP3 inflammasome and microtubule-destabilizing agents such as colchicine have been shown to suppress the activation of this inflammasome. However, it remains largely unknown whether paclitaxel, a microtubule-stabilizing agent being used in cancer therapy, has any influences on NLRP3 inflammasome activation. Here we showed that paclitaxel pre-treatment greatly enhanced ATP- or nigericin-induced NLRP3 inflammasome activation as indicated by increased release of cleaved caspase-1 and mature IL-1β, enhanced formation of ASC speck, and increased gasdermin D cleavage and pyroptosis. Paclitaxel time- and dose-dependently induced α-tubulin acetylation in LPS-primed murine and human macrophages and further increased ATP- or nigericin-induced α-tubulin acetylation. Such increased α-tubulin acetylation was significantly suppressed either by resveratrol or NAD+ (coenzyme required for deacetylase activity of SIRT2), or by genetic knockdown of MEC-17 (gene encoding α-tubulin acetyltransferase 1). Concurrently, the paclitaxel-mediated enhancement of NLRP3 inflammasome activation was significantly suppressed by resveratrol, NAD+, or MEC-17 knockdown, indicating the involvement of paclitaxel-induced α-tubulin acetylation in the augmentation of NLRP3 inflammasome activation. Similar to paclitaxel, epothilone B that is another microtubule-stabilizing agent also induced α-tubulin acetylation and increased NLRP3 inflammasome activation in macrophages in response to ATP treatment. Consistent with the in vitro results, intraperitoneal administration of paclitaxel significantly increased serum IL-1β levels, reduced bacterial burden, dampened infiltration of inflammatory cells in the liver, and improved animal survival in a mouse model of bacterial infection. Collectively, our data indicate that paclitaxel potentiated NLRP3 inflammasome activation by inducing α-tubulin acetylation and thereby conferred enhanced antibacterial innate responses, suggesting its potential application against pathogenic infections beyond its use as a chemotherapeutic agent.

Dataset Information

Microtubule-Mediated NLRP3 Inflammasome Activation Is Independent of Microtubule-Associated Innate Immune Factor GEF-H1 in Murine Macrophages.

Publications

Microtubule-Mediated NLRP3 Inflammasome Activation Is Independent of Microtubule-Associated Innate Immune Factor GEF-H1 in Murine Macrophages.

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