scholarly journals The C. elegans RIG-I homolog drh-1 mediates the Intracellular Pathogen Response upon viral infection

2019 ◽  
Author(s):  
Jessica N. Sowa ◽  
Hongbing Jiang ◽  
Lakshmi Somasundaram ◽  
Guorong Xu ◽  
David Wang ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Polymerase Activity ◽  
Intracellular Pathogen ◽  
Rna Dependent Rna Polymerase ◽  
C Elegans ◽  
Proteotoxic Stress ◽  
Rna Polymerase Activity ◽  
Pathogen Response ◽  
Orsay Virus ◽  
Recognition Receptor

AbstractMammalian RIG-I-like receptors detect viral dsRNA and 5’ triphosphorylated RNA to activate transcription of interferon genes and promote antiviral defense. The C. elegans RIG-I-like receptor DRH-1 promotes defense through antiviral RNA interference, but less is known about its role in regulating transcription. Here we describe a role for drh-1 in directing a transcriptional response in C. elegans called the Intracellular Pathogen Response (IPR), which is associated with increased pathogen resistance. The IPR includes a set of genes induced by diverse stimuli including intracellular infection and proteotoxic stress. Previous work suggested that the proteotoxic stress caused by intracellular infections might be the common trigger of the IPR, but here we demonstrate that different stimuli act through distinct pathways. Specifically, we demonstrate that DRH-1/RIG-I is required for inducing the IPR in response to Orsay virus infection, but not in response to other triggers like microsporidian infection or proteotoxic stress. Furthermore, drh-1 appears to be acting independently of its known role in RNAi. Interestingly, expression of the replication competent Orsay virus RNA1 segment alone is sufficient to induce most of the IPR genes in a manner dependent on RNA dependent RNA polymerase activity and on drh-1. Altogether, these results suggest that DRH-1 is a pattern-recognition receptor that detects viral replication products to activate the IPR stress/immune program in C. elegans.ImportanceC. elegans lacks homologs of most mammalian pattern recognition receptors, and how nematodes detect pathogens is poorly understood. We show that the C. elegans RIG-I homolog drh-1 mediates induction of the Intracellular Pathogen Response (IPR), a novel transcriptional defense program, in response to infection by the natural C. elegans viral pathogen Orsay virus. drh-1 appears to act as a pattern-recognition receptor to induce the IPR transcriptional defense program by sensing the products of viral RNA-dependent RNA polymerase activity. Interestingly, this signaling role of drh-1 is separable from its previously known role in antiviral RNAi. In addition, we show that there are multiple host pathways for inducing the IPR, shedding light on the regulation of this novel transcriptional immune response.

scholarly journals The Caenorhabditis elegans RIG-I Homolog DRH-1 Mediates the Intracellular Pathogen Response upon Viral Infection

2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Jessica N. Sowa ◽  
Hongbing Jiang ◽  
Lakshmi Somasundaram ◽  
Eillen Tecle ◽  
Guorong Xu ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Polymerase Activity ◽  
Intracellular Pathogen ◽  
Content Type ◽  
C Elegans ◽  
Proteotoxic Stress ◽  
Rna Polymerase Activity ◽  
Pathogen Response ◽  
Orsay Virus ◽  
Recognition Receptor

ABSTRACT Mammalian retinoic acid-inducible gene I (RIG-I)-like receptors detect viral double-stranded RNA (dsRNA) and 5′-triphosphorylated RNA to activate the transcription of interferon genes and promote antiviral defense. The Caenorhabditis elegans RIG-I-like receptor DRH-1 promotes defense through antiviral RNA interference (RNAi), but less is known about its role in regulating transcription. Here, we describe a role for DRH-1 in directing a transcriptional response in C. elegans called the intracellular pathogen response (IPR), which is associated with increased pathogen resistance. The IPR includes a set of genes induced by diverse stimuli, including intracellular infection and proteotoxic stress. Previous work suggested that the proteotoxic stress caused by intracellular infections might be the common trigger of the IPR, but here, we demonstrate that different stimuli act through distinct pathways. Specifically, we demonstrate that DRH-1/RIG-I is required for inducing the IPR in response to Orsay virus infection but not in response to other triggers like microsporidian infection or proteotoxic stress. Furthermore, DRH-1 appears to be acting independently of its known role in RNAi. Interestingly, expression of the replication-competent Orsay virus RNA1 segment alone is sufficient to induce most of the IPR genes in a manner dependent on RNA-dependent RNA polymerase activity and on DRH-1. Altogether, these results suggest that DRH-1 is a pattern recognition receptor that detects viral replication products to activate the IPR stress/immune program in C. elegans. IMPORTANCE C. elegans lacks homologs of most mammalian pattern recognition receptors, and how nematodes detect pathogens is poorly understood. We show that the C. elegans RIG-I homolog DRH-1 mediates the induction of the intracellular pathogen response (IPR), a novel transcriptional defense program, in response to infection by the natural C. elegans viral pathogen Orsay virus. DRH-1 appears to act as a pattern recognition receptor to induce the IPR transcriptional defense program by sensing the products of viral RNA-dependent RNA polymerase activity. Interestingly, this signaling role of DRH-1 is separable from its previously known role in antiviral RNAi. In addition, we show that there are multiple host pathways for inducing the IPR, shedding light on the regulation of this novel transcriptional immune response.

scholarly journals Heat Stress Reduces the Susceptibility of Caenorhabditis elegans to Orsay Virus Infection

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1161
Author(s):  
Yuqing Huang ◽  
Mark G. Sterken ◽  
Koen van Zwet ◽  
Lisa van Sluijs ◽  
Gorben P. Pijlman ◽  
...  
Keyword(s):  
Heat Stress ◽  
Caenorhabditis Elegans ◽  
Virus Infection ◽  
Intracellular Pathogen ◽  
Potential Candidate ◽  
Molecular Responses ◽  
C Elegans ◽  
Pathogen Response ◽  
Orsay Virus ◽  
Natural Virus

The nematode Caenorhabditis elegans has been a versatile model for understanding the molecular responses to abiotic stress and pathogens. In particular, the response to heat stress and virus infection has been studied in detail. The Orsay virus (OrV) is a natural virus of C. elegans and infection leads to intracellular infection and proteostatic stress, which activates the intracellular pathogen response (IPR). IPR related gene expression is regulated by the genes pals-22 and pals-25, which also control thermotolerance and immunity against other natural pathogens. So far, we have a limited understanding of the molecular responses upon the combined exposure to heat stress and virus infection. We test the hypothesis that the response of C. elegans to OrV infection and heat stress are co-regulated and may affect each other. We conducted a combined heat-stress-virus infection assay and found that after applying heat stress, the susceptibility of C. elegans to OrV was decreased. This difference was found across different wild types of C. elegans. Transcriptome analysis revealed a list of potential candidate genes associated with heat stress and OrV infection. Subsequent mutant screens suggest that pals-22 provides a link between viral response and heat stress, leading to enhanced OrV tolerance of C. elegans after heat stress.

scholarly journals An intracellular pathogen response pathway promotes proteostasis in C. elegans

2017 ◽  
Author(s):  
Kirthi C. Reddy ◽  
Tal Dror ◽  
Jessica N. Sowa ◽  
Johan Panek ◽  
Kevin Chen ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Intracellular Pathogen ◽  
Forward Genetic Screen ◽  
C Elegans ◽  
Transcriptional Signature ◽  
Proteotoxic Stress ◽  
Ubiquitin Ligase Complex ◽  
Pathogen Response ◽  
Mutant Phenotypes ◽  
Increased Activity

SummaryMaintenance of proteostasis is critical for organismal health. Here we describe a novel pathway that promotes proteostasis, identified through the analysis of C. elegans genes upregulated by intracellular infection. We named this distinct transcriptional signature the Intracellular Pathogen Response (IPR), and it includes upregulation of several predicted ubiquitin ligase complex components such as the cullin cul-6. Through a forward genetic screen we found pals-22, a gene of previously unknown function, to be a repressor of the cul-6/Cullin gene and other IPR gene expression. Interestingly, pals-22 mutants have increased thermotolerance and reduced levels of stress-induced polyglutamine aggregates, likely due to upregulated IPR expression. We found the enhanced stress resistance of pals-22 mutants to be dependent on cul-6, suggesting that pals-22 mutants have increased activity of a CUL-6/Cullin-containing ubiquitin ligase complex. pals-22 mutant phenotypes are distinct from the well-studied heat shock and insulin signaling pathways, indicating that the IPR is a novel pathway that protects animals from proteotoxic stress.

scholarly journals Balancing selection of the Intracellular Pathogen Response in natural Caenorhabditis elegans populations

2019 ◽  
Author(s):  
Lisa van Sluijs ◽  
Kobus J. Bosman ◽  
Frederik Pankok ◽  
Tatiana Blokhina ◽  
Joost A. G. Riksen ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Caenorhabditis Elegans ◽  
Balancing Selection ◽  
Model Organism ◽  
Evolutionary Strategies ◽  
Intracellular Pathogen ◽  
C Elegans ◽  
Pathogen Response ◽  
Orsay Virus ◽  
Selection Of

AbstractBackgroundGenetic variation in host populations may lead to differential viral susceptibilities. Here, we investigate the role of natural genetic variation present for an antiviral pathway, the Intracellular Pathogen Response (IPR), underlying susceptibility to Orsay virus in the model organism Caenorhabditis elegans. The IPR involves transcriptional activity of 80 genes including the pals-genes. The pals-genes form an expanded gene family which hints they could be shaped by an evolutionary selective pressure. Here we examine the genetic variation in the pals-family for traces of selection and explore the molecular and phenotypic effects of having distinct pals-gene alleles.ResultsGenetic analysis of 330 world-wide C. elegans strains reveals that genetic diversity within the IPR-related pals-genes can be categorized in a few haplotypes worldwide. Importantly, two key-IPR regulators, pals-22 and pals-25, are in a genomic region carrying signatures of balancing selection. Therefore, distinct pals-22/pals-25 alleles have been maintained in C. elegans populations over time, which suggests different evolutionary strategies exist in IPR regulation. We investigated the IPR by infecting two C. elegans strains that represent distinct pals-22/pals-25 haplotypes, N2 and CB4856, with Orsay virus to determine their susceptibility and transcriptional response to infection. Our data suggests that regulatory genetic variation underlies constant high activity of IPR genes in CB4856 which could determine the host transcriptional defense. We found that CB4856 shows initially lower viral susceptibility than N2. High basal IPR expression levels might help counteract viral infection directly, whereas N2-like strains that need to activate the IPR genes first may have a slower response. Nevertheless, most wild strains harbor N2-like alleles for the pals-genes.ConclusionsOur work provides evidence for balancing genetic selection of immunity genes in C. elegans and illustrated how this may shape the transcriptional defense against pathogens. The transcriptional and genetic data presented in this study therefore provide a novel perspective on the functional diversity that can develop within a main antiviral response in natural host populations.

scholarly journals A cullin-RING ubiquitin ligase promotes thermotolerance as part of the intracellular pathogen response inCaenorhabditis elegans

2020 ◽  
Vol 117 (14) ◽  
pp. 7950-7960 ◽  
Author(s):  
Johan Panek ◽  
Spencer S. Gang ◽  
Kirthi C. Reddy ◽  
Robert J. Luallen ◽  
Amitkumar Fulzele ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Intracellular Pathogen ◽  
Intracellular Pathogens ◽  
Core Component ◽  
C Elegans ◽  
Proteotoxic Stress ◽  
Expression Of Genes ◽  
Core Components ◽  
Pathogen Response ◽  
Related Proteins

Intracellular pathogen infection leads to proteotoxic stress in host organisms. Previously we described a physiological program in the nematodeCaenorhabditis eleganscalled the intracellular pathogen response (IPR), which promotes resistance to proteotoxic stress and appears to be distinct from canonical proteostasis pathways. The IPR is controlled by PALS-22 and PALS-25, proteins of unknown biochemical function, which regulate expression of genes induced by natural intracellular pathogens. We previously showed that PALS-22 and PALS-25 regulate the mRNA expression of the predicted ubiquitin ligase component cullincul-6, which promotes thermotolerance inpals-22mutants. However, it was unclear whether CUL-6 acted alone, or together with other cullin-ring ubiquitin ligase components, which comprise a greatly expanded gene family inC. elegans. Here we use coimmunoprecipitation studies paired with genetic analysis to define the cullin-RING ligase components that act together with CUL-6 to promote thermotolerance. First, we identify a previously uncharacterized RING domain protein in the TRIM family we named RCS-1, which acts as a core component with CUL-6 to promote thermotolerance. Next, we show that the Skp-related proteins SKR-3, SKR-4, and SKR-5 act redundantly to promote thermotolerance with CUL-6. Finally, we screened F-box proteins that coimmunoprecipitate with CUL-6 and find that FBXA-158 and FBXA-75 promote thermotolerance. In summary, we have defined the three core components and two F-box adaptors of a cullin-RING ligase complex that promotes thermotolerance as part of the IPR inC. elegans, which adds to our understanding of how organisms cope with proteotoxic stress.

scholarly journals A cullin-RING ubiquitin ligase promotes thermotolerance as part of the Intracellular Pathogen Response in C. elegans

2019 ◽  
Author(s):  
Johan Panek ◽  
Spencer S. Gang ◽  
Kirthi C. Reddy ◽  
Robert J. Luallen ◽  
Amitkumar Fulzele ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Protein Quality ◽  
Transcriptional Response ◽  
Intracellular Pathogen ◽  
Protein Homeostasis ◽  
Pathogen Infection ◽  
C Elegans ◽  
Proteotoxic Stress ◽  
Expression Of Genes ◽  
Pathogen Response

AbstractIntracellular pathogen infection leads to proteotoxic stress in host organisms. Previously we described a physiological program in the nematode C. elegans called the Intracellular Pathogen Response (IPR), which promotes resistance to proteotoxic stress and appears to be distinct from canonical proteostasis pathways. The IPR is controlled by PALS-22 and PALS-25, proteins of unknown biochemical function, which regulate expression of genes induced by natural intracellular pathogens. We previously showed that PALS-22 and PALS-25 regulate the mRNA expression of the predicted ubiquitin ligase component cullin cul-6, which promotes thermotolerance in pals-22 mutants. However, it was unclear whether CUL-6 acted alone, or together with other ubiquitin ligase components. Here we use co-immunoprecipitation studies paired with genetic analysis to define the cullin-RING ligase components that act together with CUL-6 to promote thermotolerance. First, we identify a previously uncharacterized RING domain protein in the TRIM family we named RCS-1, which acts as a core component with CUL-6 to promote thermotolerance. Next, we show that the Skp-related proteins SKR-3, SKR-4 and SKR-5 act redundantly to promote thermotolerance with CUL-6. Finally, we screened F-box proteins that co-immunoprecipitate with CUL-6 and find that FBXA-158 promotes thermotolerance. In summary, we have defined the three core components and an F-box adaptor of a cullin-RING ligase complex that promotes thermotolerance as part of the IPR in C. elegans, which adds to our understanding of how organisms cope with proteotoxic stress.Significance StatementIntracellular pathogen infection in the nematode Caenorhabditis elegans induces a robust transcriptional response as the host copes with infection. This response program includes several ubiquitin ligase components that are predicted to function in protein quality control. In this study, we show that these infection-induced ubiquitin ligase components form a protein complex that promotes increased tolerance of acute heat stress, an indicator of improved protein homeostasis capacity. These findings show that maintaining protein homeostasis may be a critical component of a multifaceted approach allowing the host to deal with stress caused by intracellular infection.

scholarly journals Thermolabile L-A virus-like particles from pet18 mutants of Saccharomyces cerevisiae.

1986 ◽  
Vol 6 (2) ◽  
pp. 404-410 ◽  
Author(s):  
T Fujimura ◽  
R B Wickner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Polymerase Activity ◽  
Nonpermissive Temperature ◽  
Wild Type ◽  
Rna Dependent Rna Polymerase ◽  
Virus Like Particles ◽  
Rna Polymerase Activity ◽  
Lines Of Evidence

pet18 mutations in Saccharomyces cerevisiae confer on the cell the inability to maintain either L-A or M double-stranded RNAs (dsRNAs) at the nonpermissive temperature. In in vitro experiments, we examined the effects of pet18 mutations on the RNA-dependent RNA polymerase activity associated with virus-like particles (VLPs). pet18 mutations caused thermolabile RNA polymerase activity of L-A VLPs, and this thermolability was found to be due to the instability of the L-A VLP structure. The pet18 mutations did not affect RNA polymerase activity of M VLPs. Furthermore, the temperature sensitivity of wild-type L-A RNA polymerase differed substantially from that of M RNA polymerase. From these results, and from other genetic and biochemical lines of evidence which suggest that replication of M dsRNA requires the presence of L-A dsRNA, we propose that the primary effect of the pet18 mutation is on the L-A VLP structure and that the inability of pet18 mutants to maintain M dsRNA comes from the loss of L-A dsRNA.

An Assay for RNA-Dependent RNA Polymerase Activity

2006 ◽  
Vol 2006 (1) ◽  
pp. pdb.prot4322
Author(s):  
Luyun Huang ◽  
John Gledhill ◽  
Craig E. Cameron
Keyword(s):  
Rna Polymerase ◽  
Polymerase Activity ◽  
Rna Dependent Rna Polymerase ◽  
Rna Polymerase Activity
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