Innate immunity in the C. elegans intestine is programmed by a neuronal regulator of AWC olfactory neuron development
Ontology highlight
ABSTRACT:
ORGANISM(S): Caenorhabditis elegans
PROVIDER: GSE130959 | GEO | 2020/03/04
REPOSITORIES: GEO
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Project description:Gap junctions mediate intercellular communications across cellular networks in the nervous and the immune systems, while the role in the intestinal innate immunity is poorly understood. Here, we identified that an innexin gene inx-14 encoding one of heterotypic and heteromeric gap junction subunits acts in the gonad to attenuate the intestinal defense through PMK-1/p38 pathway. The RNA-seq analyses revealed that GLP-1/Notch signaling was downregulated, while lysosome, and PMK-1/p38 MAPK signalings were upregulated by the germline-specific inx-14 RNAi in C. elegans. Loss function of either inx-14, or glp-1 exhibited enhanced resistance to PA14 infection and upregulated lysosome and PMK-1/p38 signalings. Additionally, inx-14 knockdown by germline specific RNAi upregulated muscarinic acetylcholine receptor (mAChR) genes gar-1/gar-2/gar-3. We further revealed that acetylcholine mAChR GAR-2/GAR-3 signaling functions in the intestine and downstream of lysosome signaling but upstream of PMK-1/p38 pathway to facilitate the intestinal defense. Our findings reveal a novel role for gonadal gap junction/INX-14 in host intestinal defense against pathogens and expand our understanding the functions of reproductive system in the host intestinal defense.
2023-11-01 | GSE216879 | GEO
Project description:The nervous system comprises diverse and highly specialized neuron-types, each expressing a unique set of genes that defines its functional properties. What molecular mechanisms generate diverse neuron types remains a central question in neuroscience. Our study of C. elegans chemosensory BAG neurons showed that a p38 MAP kinase (MAPK), PMK-3, is required for their proper differentiation and function (Brandt, J. and Ringstad, N. 2015). How p38 MAPKs function in neurodifferentiation is poorly understood. To better understand how pmk-3 promotes the BAG cell fate, we purified wild-type and pmk-3 mutant chemosensory BAG neurons and determined their transcriptomes using RNA-Seq. Expression of a number of genes that encode neuropeptides, including insulin-like peptides (ILPs), were up-regulated in pmk-3 mutant BAG neurons. Through analysis of mutations that restore expression of a BAG-fate marker to pmk-3 mutants, we additionally found that genes required for the release of neuropeptides, including UNC-31/CAPS, suppress pmk-3 mutant gene expression defects. These two observations suggested that the differentiation defects of pmk-3 mutants are associated with dysregulated release of peptide hormones. Indeed, we find that increased synthesis and release of ILPs from BAG during development causes a significant fraction of the gene expression and functional defects of pmk-3 mutant neurons. Together our data delineate a mechanism through which p38 MAPKs promote proper sensory neuron differentiation by inhibiting an autocrine insulin signal that represses expression of a BAG neuron fate. These findings reveal an unexpected role for insulin signaling in nervous system development and suggest that insulin-like factors are at the nexus of intrinsic genetic programs and extrinsic signaling mechanisms that regulate cell fate and neuronal differentiation.
2019-09-12 | GSE137267 | GEO
Project description:Discriminating pathogenic bacteria from energy-harvesting commensals is key to host immunity. Using mutants defective in the enzymes of O-linked N-acetylglucosamine (O-GlcNAc) cycling, we examined the role of this nutrient-sensing pathway in the Caenorhabidits elegans innate immune response. Using whole genome transcriptional profiling, O-GlcNAc cycling mutants exhibited deregulation of unique stress- and immune-responsive genes as well as genes shared with the p38 MAPK/PMK-1 pathway. Moreover, genetic analysis showed that deletion of O-GlcNAc transferase (ogt-1) yielded animals hypersensitive to the human pathogen S. aureus but not to P. aeruginosa. Genetic interaction studies further revealed that nutrient-responsive OGT-1 acts through the conserved ß-catenin (BAR-1) pathway and in concert with p38 MAPK/PMK-1 to modulate the immune response to S. aureus. The participation of the nutrient sensor O-GlcNAc transferase in an immunity module conserved from C. elegans to humans reveals an unexplored nexus between nutrient availability and a pathogen-specific immune response. In C. elegans, three mutant strains(genotypes used: N2 (wild-type), ogt-1 (ok1474), oga-1 (ok1207), and pmk-1 (km25)) were treated with the human pathogen S. aureus (SA) or P. aeruginosa(PA) and OP50 (E. coli control) with three biological replications.
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Project description:Intracellular signaling regulators are concentrated into membrane-free, higher-ordered protein assemblies to initiate protective responses during stress — a process known as phase transition. Here, we show that a phase transition of the C. elegans Toll/interleukin-1 receptor domain protein (TIR-1), a homolog of the mammalian sterile alpha and TIR motif-containing 1 (SARM1), primes host immune defenses when dietary sterols are limited to handle subsequent bacterial infection. TIR-1/SARM1 is an upstream component of the p38 PMK-1 pathway in intestinal cells, an innate immune defense and stress response pathway in metazoans. Under conditions of low cholesterol availability, multimerization and precipitation of TIR-1/SARM1 potentiates the intrinsic NAD+ glycohydrolase activity of this protein complex, increases p38 PMK-1 phosphorylation, and promotes pathogen clearance from the intestine. Dietary cholesterol is required for C. elegans to survive infection with pathogenic bacteria and to support development, fecundity, and lifespan. Thus, activation of the p38 PMK-1 pathway in sterol-deficient animals is an adaptive response that allows a metazoan host to anticipate environmental threats under conditions of essential metabolite scarcity.
2022-03-18 | GSE178572 | GEO
Project description:Intracellular signaling regulators can be concentrated into membrane-free, higher-ordered protein assemblies to initiate protective responses during stress — a process known as phase transition. Here, we show that a phase transition of the Caenorhabditis elegans Toll/interleukin-1 receptor domain protein (TIR-1), an NAD+ glycohydrolase homologous to mammalian sterile alpha and TIR motif-containing 1 (SARM1), underlies p38 PMK-1 immune pathway activation in C. elegans intestinal epithelial cells. Through visualization of fluorescently labeled TIR-1/SARM1 protein, we demonstrate for the first time that physiologic stresses, both pathogen and non-pathogen, induce multimerization of TIR-1/SARM1 into visible puncta within intestinal epithelial cells. In vitro enzyme kinetic analyses revealed that, like mammalian SARM1, the NAD+ glycohydrolase activity of C. elegans TIR-1 is dramatically potentiated by protein oligomerization and a phase transition. Accordingly, C. elegans with genetic mutations that specifically block either multimerization or the NAD+ glycohydrolase activity of TIR-1/SARM1 fail to induce p38 PMK phosphorylation, are unable to increase immune effector expression, and are dramatically susceptible to bacterial infection. Finally, we demonstrate that low cholesterol stress causes TIR-1/SARM1 to oligomerize into puncta in intestinal epithelial cells and engages its NAD+ glycohydrolase activity, which increases p38 PMK-1 phosphorylation, and primes immune effector induction in a manner that leads to reduced pathogen accumulation in the intestine during a subsequent infection. These data reveal a new adaptive response that allows a metazoan host to anticipate pathogen threats during micronutrient deprivation, a time of relative susceptibility to infection. Thus, a phase transition of TIR-1/SARM1 as a prerequisite for its NAD+ glycohydrolase activity is strongly conserved across millions of years of evolution and is essential for diverse physiological processes in multiple cell types.
2021-12-16 | GSE190585 | GEO
Project description:Cisplatin kills proliferating cells via DNA damage but also has profound effects on post-mitotic cells in tumors, kidneys, and neurons. However, the effects of cisplatin on post-mitotic cells are still poorly understood. Among model systems, C. elegans adults are unique in having completely post-mitotic somatic tissues. The p38 MAPK pathway controls ROS detoxification via SKN-1/NRF and immune responses via ATF-7/ATF2. We show that p38 MAPK pathway mutants are sensitive to cisplatin, but while cisplatin exposure increases ROS levels, skn-1 mutants are resistant. Cisplatin exposure leads to phosphorylation of PMK-1/MAPK and ATF-7 and the IRE-1/TRF-1 signaling module functions upstream of the p38 MAPK pathway to activate signaling. We identify the response proteins whose increased abundance depends on IRE-1/p38 MAPK activity as well as cisplatin exposure. Four of these proteins are necessary for protection from cisplatin toxicity, which is characterized by necrotic death. We conclude that the p38 MAPK pathway-driven proteins are crucial for adult cisplatin resilience.
2023-04-26 | PXD033377 | Pride
Project description:Discriminating pathogenic bacteria from energy-harvesting commensals is key to host immunity. Using mutants defective in the enzymes of O-linked N-acetylglucosamine (O-GlcNAc) cycling, we examined the role of this nutrient-sensing pathway in the Caenorhabidits elegans innate immune response. Using whole genome transcriptional profiling, O-GlcNAc cycling mutants exhibited deregulation of unique stress- and immune-responsive genes as well as genes shared with the p38 MAPK/PMK-1 pathway. Moreover, genetic analysis showed that deletion of O-GlcNAc transferase (ogt-1) yielded animals hypersensitive to the human pathogen S. aureus but not to P. aeruginosa. Genetic interaction studies further revealed that nutrient-responsive OGT-1 acts through the conserved ß-catenin (BAR-1) pathway and in concert with p38 MAPK/PMK-1 to modulate the immune response to S. aureus. The participation of the nutrient sensor O-GlcNAc transferase in an immunity module conserved from C. elegans to humans reveals an unexplored nexus between nutrient availability and a pathogen-specific immune response.
2015-05-01 | GSE53732 | GEO
Project description:Many pathogens secrete toxins that target key host processes resulting in the activation of immune pathways. The secreted Pseudomonas aeruginosa toxin Exotoxin A (ToxA) disrupts intestinal protein synthesis which triggers the induction of a subset of P. aeruginosa-response genes in the nematode Caenorhabditis elegans. We found that losing one ToxA-induced C. elegans gene, the Tribbles pseudokinase ortholog nipi-3, results in hypersusceptibility to both P. aeruginosa and ToxA. We determined that NIPI-3 mediates the post-developmental expression of intestinal immune genes and proteins and primarily functions in parallel to known immune pathways, including p38 PMK-1 MAPK signaling. Here we present the microarray data that was used to determine that (1) nipi-3 regulates immune gene expression and that (2) nipi-3 and pmk-1 regulate non-overlapping gene sets consistent with them functioning in parallel. We used microarray analysis to identify the genes regulated by nipi-3 and pmk-1 at the L4 stage.
2016-09-18 | GSE87052 | GEO
Project description:Traditional treatments for bacterial infection have focused upon directly inhibiting growth of the pathogen. However, an equally important determinant of infection outcome is the host defense response. We previously performed a high-throughput chemical screen to identify small molecules that rescued the nematode Caenorhabditis elegans from infection by Pseudomonas aeruginosa. Over 20 of the hits stimulated host defense gene expression. During in-depth studies of five such molecules using microarray analysis, bioinformatic clustering, and RNAi knockdown of candidate gene targets, we identified PMK-1/p38 MAPK and SKN-1/Nrf2 as two key pathways modulated by these hits. Interestingly, the molecules studied did not depend on a single pathway for ameliorating P. aeruginosa pathogenesis in liquid-based assay, but did rely on the PMK-1/p38 MAPK pathway during a colonization-based infection assay on agar. A subset of these molecules was also protective against Enterococcus faecalis and Staphylococcus aureus. In general, the compounds showed little toxicity against mammalian cells or worms, consistent with their identification in a phenotypic, high-content screen. These molecules possess significant potential for use as tools to study innate immune processes
2020-09-19 | GSE137516 | GEO
Project description:Germline-encoded pattern recognition receptors (e.g. Toll-like receptors) play key roles in innate immune activation. However, some metazoans, such as C. elegans, do not have canonical mechanisms of pattern recognition, yet they are able to mount anti-pathogen immune defenses. Here, we demonstrate that a nuclear hormone receptor (NHR), a ligand-gated transcription factor, functions in immune activation and pathogen defense. NHRs have expanded dramatically in C. elegans compared to other metazoans. Because NHRs often function redundantly, it has been challenging experimentally to characterize the biology of individual NHRs. Here, we use genetic epistasis experiments, transcriptome profiling analyses and chromatin immunoprecipitation to show NHR-86 is sufficient to activate protective immune defenses against the bacterial pathogen Pseudomonas aeruginosa. Interestingly, NHR-86 drives the transcription of immune effectors whose basal regulation requires the canonical p38 MAPK PMK-1 immune pathway. However, NHR-86 functions independently of PMK-1 and directly induces the transcription of infection response genes in a manner that confers protection from bacterial infection. Importantly, we found that nhr-86 does control immune gene expression and is necessary for host defense against a different pathogen, Enterococcus faecalis. Our findings characterize an ancient role of an NHR in innate immunity, and suggest that the expansion of the NHR protein family in C. elegans has been fueled in part by the need to activate immune defenses in response to pathogen attack.
2019-01-09 | GSE117719 | GEO