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 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 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 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 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 Organismal Protein Homeostasis Mechanisms

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 889-901 ◽  
Author(s):  
Thorsten Hoppe ◽  
Ehud Cohen
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Protein Homeostasis ◽  
Control Mechanisms ◽  
Dynamic Regulation ◽  
C Elegans ◽  
Selective Degradation ◽  
Proteotoxic Stress ◽  
Health And Disease ◽  
Folded Proteins

Sustaining a healthy proteome is a lifelong challenge for each individual cell of an organism. However, protein homeostasis or proteostasis is constantly jeopardized since damaged proteins accumulate under proteotoxic stress that originates from ever-changing metabolic, environmental, and pathological conditions. Proteostasis is achieved via a conserved network of quality control pathways that orchestrate the biogenesis of correctly folded proteins, prevent proteins from misfolding, and remove potentially harmful proteins by selective degradation. Nevertheless, the proteostasis network has a limited capacity and its collapse deteriorates cellular functionality and organismal viability, causing metabolic, oncological, or neurodegenerative disorders. While cell-autonomous quality control mechanisms have been described intensely, recent work on Caenorhabditis elegans has demonstrated the systemic coordination of proteostasis between distinct tissues of an organism. These findings indicate the existence of intricately balanced proteostasis networks important for integration and maintenance of the organismal proteome, opening a new door to define novel therapeutic targets for protein aggregation diseases. Here, we provide an overview of individual protein quality control pathways and the systemic coordination between central proteostatic nodes. We further provide insights into the dynamic regulation of cellular and organismal proteostasis mechanisms that integrate environmental and metabolic changes. The use of C. elegans as a model has pioneered our understanding of conserved quality control mechanisms important to safeguard the organismal proteome in health and disease.

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 Locked in a vicious cycle: the connection between genomic instability and a loss of protein homeostasis

2020 ◽  
Author(s):  
Wouter Huiting ◽  
Steven Bergink
Keyword(s):  
Control Systems ◽  
Genomic Instability ◽  
Therapeutic Strategy ◽  
Protein Quality ◽  
Accelerated Ageing ◽  
Protein Homeostasis ◽  
Vicious Cycle ◽  
Proteotoxic Stress ◽  
Gradual Loss ◽  
Wide Range

AbstractCardiomyopathies, neuropathies, cancer and accelerated ageing are unequivocally distinct diseases, yet they also show overlapping pathological hallmarks, including a gradual loss of genomic integrity and proteotoxic stress. Recent lines of evidence suggest that this overlap could be the result of remarkably interconnected molecular cascades between nuclear genomic instability and a loss of protein homeostasis. In this review, we discuss these complex connections, as well as their possible impact on disease. We focus in particular on the inherent ability of a wide range of genomic alterations to challenge protein homeostasis. In doing so, we provide evidence suggesting that a loss of protein homeostasis could be a far more prevalent consequence of genomic instability than generally believed. In certain cases, such as aneuploidy, a loss of protein homeostasis appears to be a crucial mechanism for pathology, which indicates that enhancing protein quality control systems could be a promising therapeutic strategy in diseases associated with genomic instability.

scholarly journals An Intracellular Pathogen Response Pathway Promotes Proteostasis in C. elegans

2017 ◽  
Vol 27 (22) ◽  
pp. 3544-3553.e5 ◽  
Author(s):  
Kirthi C. Reddy ◽  
Tal Dror ◽  
Jessica N. Sowa ◽  
Johan Panek ◽  
Kevin Chen ◽  
...  
Keyword(s):  
Intracellular Pathogen ◽  
C Elegans ◽  
Pathogen Response

scholarly journals THE ENDOPLASMIC RETICULUM PROTEIN QUALITY CONTROL ADAPTATION IN A LONG-LIVED C. ELEGANS PROTEASOMAL MUTANT

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S99-S99
Author(s):  
Meghna N Chinchankar ◽  
Karl Rodriguez ◽  
Alfred Fisher
Keyword(s):  
Stress Resistance ◽  
Protein Quality ◽  
Underlying Mechanism ◽  
26S Proteasome ◽  
Protein Homeostasis ◽  
Catalytic Core ◽  
C Elegans ◽  
Endoplasmic Reticulum Protein ◽  
Extended Lifespan ◽  
Er Homeostasis

Abstract Protein degradation mechanisms are integral to protein homeostasis. Their reduced efficiency during aging leads to accumulation of misfolded and aggregated proteins which potentiate proteotoxic disorders. Paradoxically, our lab reported that the Caenorhabditis elegans rpn-10(ok1865) proteasome mutant possesses enhanced proteostasis and extended lifespan. RPN-10/PSMD4 is a ubiquitin receptor of the 26S proteasome that targets polyubiquitinated substrates to its catalytic core for degradation. Proteasome dysfunction of the rpn-10 mutant is characterized by reduced, not inhibited, ubiquitin fusion degradation. We ascertained that upregulated autophagy and SKN-1/Nrf-mediated responses partially contribute to the robust rpn-10 mutant phenotype. Further investigation of its underlying mechanism revealed that several ERQC genes are transcriptionally upregulated in the rpn-10 mutant. Thus, we hypothesized that the rpn-10 mutant exhibits improved ER proteostasis which mediates its elevated cellular stress resistance. Accordingly, the rpn-10 mutant shows increased ER stress resistance and altered ER homeostasis. Complementarily, attenuated expression of the aggregation-prone α-1 antitrypsin (ATZ) reporter proves that ER proteostasis is ameliorated in the rpn-10 mutant. Via a genetic screen for suppressors of decreased ATZ aggregation in the rpn-10 mutant, we identified novel player H04D03.3, which is a homolog of the proteasome adaptor ECM29. This suggests that assembly of the rpn-10 mutant proteasome itself critically regulates its ER proteostasis. Moreover, we observed that cytosolic proteostasis and longevity depend on ER master chaperone hsp-3/-4(BiP) and ER ATPase cdc-48.2(p97/VCP), further highlighting ERQC significance in the rpn-10 mutant. Altogether, it appears that mild proteasomal dysfunction induces ERQC adaptation that underlies proteostasis and longevity benefits of the rpn-10 mutant.

scholarly journals Transcriptomics-based screening identifies pharmacological inhibition of Hsp90 as a means to defer aging

2018 ◽  
Author(s):  
Georges E. Janssens ◽  
Xin-Xuan Lin ◽  
Lluís Millán-Ariño ◽  
Renée I. Seinstra ◽  
Nicholas Stroustrup ◽  
...  
Keyword(s):  
Model Organism ◽  
Protein Homeostasis ◽  
Hsp90 Inhibitors ◽  
Hsp90 Inhibition ◽  
C Elegans ◽  
Unfolded Protein ◽  
Proteotoxic Stress ◽  
Shock Proteins ◽  
Protein Response ◽  
Transcriptional State

SummaryAging is a major risk factor for human morbidity and mortality. Thus, the identification of compounds that defer aging, also known as ‘geroprotectors’, could greatly improve our health and promote a longer life. Here we screened for geroprotectors, employing the power of human transcriptomics to predict biological age. We used age-stratified human tissue transcriptomes to generate machine-learning-based classifiers capable of distinguishing transcriptomes from young versus old individuals. Then we applied these classifiers to transcriptomes induced by 1300 different compounds in human cell lines and ranked these compounds by their ability to induce a ‘youthful’ transcriptional state. Besides known geroprotectors, several new candidate compounds emerged from this ranking. Testing these in the model organismC. elegans, we identified two Hsp90 inhibitors, Monorden and Tanespimycin, which substantially extended the animals’ lifespan and improved their health. Hsp90 inhibition specifically induces the expression of heat shock proteins, known to improve protein homeostasis. Consistently, Monorden treatment improved the survival ofC. elegansunder proteotoxic stress, and its lifespan benefits were fully dependent on the master regulator of the cytosolic unfolded protein response, the transcription factor HSF-1. Taken together, we present an innovative transcriptomics-based screening approach to discover aging-preventive compounds and highlight Hsp90 inhibitors as powerful geroprotectors that could be of great value, to target the aging process in humans.

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