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González R, Félix MA. Caenorhabditis elegans immune responses to microsporidia and viruses. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 154:105148. [PMID: 38325500 DOI: 10.1016/j.dci.2024.105148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 01/30/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
The model organism Caenorhabditis elegans is susceptible to infection by obligate intracellular pathogens, specifically microsporidia and viruses. These intracellular pathogens infect intestinal cells, or, for some microsporidia, epidermal cells. Strikingly, intestinal cell infections by viruses or microsporidia trigger a common transcriptional response, activated in part by the ZIP-1 transcription factor. Among the strongest activated genes in this response are ubiquitin-pathway members and members of the pals family, an intriguing gene family with cross-regulations of different members of genomic clusters. Some of the induced genes participate in host defense against the pathogens, for example through ubiquitin-mediated inhibition. Other mechanisms defend the host specifically against viral infections, including antiviral RNA interference and uridylation. These various immune responses are altered by environmental factors and by intraspecific genetic variation of the host. These pathogens were first isolated 15 years ago and much remains to be discovered using C. elegans genetics; also, other intracellular pathogens of C. elegans may yet to be discovered.
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Affiliation(s)
- Rubén González
- Institut de Biologie de l'École Normale Supérieure, CNRS, INSERM, 75005, Paris, France.
| | - Marie-Anne Félix
- Institut de Biologie de l'École Normale Supérieure, CNRS, INSERM, 75005, Paris, France
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2
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Tran TD, Luallen RJ. An organismal understanding of C. elegans innate immune responses, from pathogen recognition to multigenerational resistance. Semin Cell Dev Biol 2024; 154:77-84. [PMID: 36966075 PMCID: PMC10517082 DOI: 10.1016/j.semcdb.2023.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/05/2023] [Accepted: 03/14/2023] [Indexed: 03/27/2023]
Abstract
The nematode Caenorhabditis elegans has been a model for studying infection since the early 2000s and many major discoveries have been made regarding its innate immune responses. C. elegans has been found to utilize some key conserved aspects of immune responses and signaling, but new interesting features of innate immunity have also been discovered in the organism that might have broader implications in higher eukaryotes such as mammals. Some of the distinctive features of C. elegans innate immunity involve the mechanisms this bacterivore uses to detect infection and mount specific immune responses to different pathogens, despite lacking putative orthologs of many important innate immune components, including cellular immunity, the inflammasome, complement, or melanization. Even when orthologs of known immune factors exist, there appears to be an absence of canonical functions, most notably the lack of pattern recognition by its sole Toll-like receptor. Instead, recent research suggests that C. elegans senses infection by specific pathogens through contextual information, including unique products produced by the pathogen or infection-induced disruption of host physiology, similar to the proposed detection of patterns of pathogenesis in mammalian systems. Interestingly, C. elegans can also transfer information of past infection to their progeny, providing robust protection for their offspring in face of persisting pathogens, in part through the RNAi pathway as well as potential new mechanisms that remain to be elucidated. Altogether, some of these strategies employed by C. elegans share key conceptual features with vertebrate adaptive immunity, as the animal can differentiate specific microbial features, as well as propagate a form of immune memory to their offspring.
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Affiliation(s)
- Tuan D Tran
- Department of Biology San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA
| | - Robert J Luallen
- Department of Biology San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA.
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3
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Rodriguez-Andres J, Axford J, Hoffmann A, Fazakerley J. Mosquito transgenerational antiviral immunity is mediated by vertical transfer of virus DNA sequences and RNAi. iScience 2024; 27:108598. [PMID: 38155780 PMCID: PMC10753076 DOI: 10.1016/j.isci.2023.108598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/23/2023] [Accepted: 11/28/2023] [Indexed: 12/30/2023] Open
Abstract
Mosquitoes are important vectors for transmission of many viruses of public and veterinary health concern. These viruses most commonly have an RNA genome and infect mosquitoes for life. The principal mosquito antiviral response is the RNAi system which destroys virus RNA. Here, we confirm an earlier study that Aedes aegypti mosquitoes infected with positive-stranded RNA arboviruses can transmit specific immunity to their offspring. We show that this trans-generational immunity requires replication of virus RNA and reverse transcription of vRNA to vDNA in the infected parents and intergenerational transfer of vDNA. This vDNA is both genome-integrated and episomal. The episomal vDNA sequences are flanked by retrotransposon long-terminal repeats, predominantly Copia-like. Integrated vDNA sequences are propagated along several generations but specific immunity is effective only for a few generations and correlates with the presence of vRNA and episomal vDNA. This understanding raises new possibilities for the control of important mosquito-borne virus diseases.
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Affiliation(s)
- Julio Rodriguez-Andres
- Department of Microbiology and Immunology, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne at the Peter Doherty Institute, Melbourne, VIC, Australia
| | - Jason Axford
- School of Biosciences, Faculty of Science at the Bio-21 Institute, University of Melbourne, Parkville, VIC, Australia
| | - Ary Hoffmann
- School of Biosciences, Faculty of Science at the Bio-21 Institute, University of Melbourne, Parkville, VIC, Australia
| | - John Fazakerley
- Department of Microbiology and Immunology, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne at the Peter Doherty Institute, Melbourne, VIC, Australia
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Kloc M, Halasa M, Kubiak JZ, Ghobrial RM. Invertebrate Immunity, Natural Transplantation Immunity, Somatic and Germ Cell Parasitism, and Transposon Defense. Int J Mol Sci 2024; 25:1072. [PMID: 38256145 PMCID: PMC10815962 DOI: 10.3390/ijms25021072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
While the vertebrate immune system consists of innate and adaptive branches, invertebrates only have innate immunity. This feature makes them an ideal model system for studying the cellular and molecular mechanisms of innate immunity sensu stricto without reciprocal interferences from adaptive immunity. Although invertebrate immunity is evolutionarily older and a precursor of vertebrate immunity, it is far from simple. Despite lacking lymphocytes and functional immunoglobulin, the invertebrate immune system has many sophisticated mechanisms and features, such as long-term immune memory, which, for decades, have been exclusively attributed to adaptive immunity. In this review, we describe the cellular and molecular aspects of invertebrate immunity, including the epigenetic foundation of innate memory, the transgenerational inheritance of immunity, genetic immunity against invading transposons, the mechanisms of self-recognition, natural transplantation, and germ/somatic cell parasitism.
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Affiliation(s)
- Malgorzata Kloc
- Houston Methodist Research Institute, Transplant Immunology, Houston, TX 77030, USA; (M.H.); (R.M.G.)
- Department of Surgery, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Genetics, MD Anderson Cancer Center, University of Texas, Houston, TX 77030, USA
| | - Marta Halasa
- Houston Methodist Research Institute, Transplant Immunology, Houston, TX 77030, USA; (M.H.); (R.M.G.)
- Department of Surgery, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Jacek Z. Kubiak
- Laboratory of Molecular Oncology and Innovative Therapies, Military Institute of Medicine-National Research Institute (WIM-PIB), Szaserow 128, 04-141 Warsaw, Poland;
- Dynamics and Mechanics of Epithelia Group, Faculty of Medicine, Institute of Genetics and Development of Rennes, University of Rennes, CNRS, UMR 6290, 35043 Rennes, France
| | - Rafik M. Ghobrial
- Houston Methodist Research Institute, Transplant Immunology, Houston, TX 77030, USA; (M.H.); (R.M.G.)
- Department of Surgery, Houston Methodist Hospital, Houston, TX 77030, USA
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5
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González R, Félix MA. Naturally-associated bacteria modulate Orsay virus infection of Caenorhabditis elegans. PLoS Pathog 2024; 20:e1011947. [PMID: 38232128 PMCID: PMC10824439 DOI: 10.1371/journal.ppat.1011947] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 01/29/2024] [Accepted: 01/04/2024] [Indexed: 01/19/2024] Open
Abstract
Microbes associated with an organism can significantly modulate its susceptibility to viral infections, but our understanding of the influence of individual microbes remains limited. The nematode Caenorhabditis elegans is a model organism that in nature inhabits environments rich in bacteria. Here, we examine the impact of 71 naturally associated bacteria on C. elegans susceptibility to its only known natural virus, the Orsay virus. Our findings reveal that viral infection of C. elegans is significantly influenced by monobacterial environments. Compared to an Escherichia coli environmental reference, the majority of tested bacteria reduced C. elegans susceptibility to viral infection. This reduction is not caused by virion degradation or poor animal nutrition by the bacteria. The repression of viral infection by the bacterial strains Chryseobacterium JUb44 and Sphingobacterium BIGb0172 does not require the RIG-I homolog DRH-1, which is known to activate antiviral responses such as RNA interference and transcriptional regulation. Our research highlights the necessity of considering natural biotic environments in viral infection studies and opens the way future research on host-microbe-virus interactions.
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Affiliation(s)
- Rubén González
- Institut de Biologie de l’École Normale Supérieure, CNRS, INSERM, Paris, France
| | - Marie-Anne Félix
- Institut de Biologie de l’École Normale Supérieure, CNRS, INSERM, Paris, France
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6
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Wibisono P, Sun J. Pathogen infection induces specific transgenerational modifications to gene expression and fitness in Caenorhabditis elegans. Front Physiol 2023; 14:1225858. [PMID: 37811492 PMCID: PMC10556243 DOI: 10.3389/fphys.2023.1225858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023] Open
Abstract
How pathogen infection in a parental generation affects response in future generations to the same pathogen via epigenetic modifications has been the topic of recent studies. These studies focused on changes attributed to transgenerational epigenetic inheritance and how these changes cause an observable difference in behavior or immune response in a population. However, we questioned if pathogen infection causes hidden epigenetic changes to fitness that are not observable at the population level. Using the nematode Caenorhabditis elegans as a model organism, we examined the generation-to-generation differences in survival of both an unexposed and primed lineage of animals against a human opportunistic pathogen Salmonella enterica. We discovered that training a lineage of C. elegans against a specific pathogen does not cause a significant change to overall survival, but rather narrows survival variability between generations. Quantification of gene expression revealed reduced variation of a specific member of the TFEB lipophagic pathway. We also provided the first report of a repeating pattern of survival times over the course of 12 generations in the control lineage of C. elegans. This repeating pattern indicates that the variability in survival between generations of the control lineage is not random but may be regulated by unknown mechanisms. Overall, our study indicates that pathogen infection can cause specific phenotypic changes due to epigenetic modifications, and a possible system of epigenetic regulation between generations.
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Affiliation(s)
- Phillip Wibisono
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, United States
| | - Jingru Sun
- Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, United States
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Rutkowski NAJ, McNamara KB, Jones TM, Foo YZ. Trans-generational immune priming is not mediated by the sex of the parent primed: a meta-analysis of invertebrate data. Biol Rev Camb Philos Soc 2023; 98:1100-1117. [PMID: 36879482 DOI: 10.1111/brv.12946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 03/08/2023]
Abstract
Traditionally, only vertebrates were thought capable of acquired immune responses, such as the ability to transfer immunological experience vertically to their offspring (known as trans-generational immune priming, TGIP). Increasing evidence challenges this belief and it is now clear that invertebrates also have the ability to exhibit functionally equivalent TGIP. This has led to a surge in papers exploring invertebrate TGIP, with most focusing on the costs, benefits or factors that affect the evolution of this trait. Whilst many studies have found support for the phenomenon, not all studies do, and there is considerable variation in the strength of positive results. To address this, we conducted a meta-analysis to answer the question: what is the overall effect of TGIP in invertebrates? Then, to understand the specific factors that affect its presence and intensity, we conducted a moderator analysis. Our results corroborate that TGIP occurs in invertebrates (demonstrated by a large, positive effect size). The strength of the positive effect was related to if and how offspring were immune challenged (i.e. whether they were challenged with the same or different insult as their parents or not challenged at all). Interestingly, there was no effect of the ecology or life history of the species or the sex of the parent or the offspring primed, and responses were comparable across different immune elicitors. Our publication bias testing suggests that the literature may suffer from some level of positive-result bias. However, even after accounting for potential bias, our effect size remains positive. Publication bias testing can be influenced by diversity in the data set, which was considerable in our data, even after moderator analysis. It is therefore conceivable that differences among studies could be caused by other moderators that were unable to be included in our meta-analysis. Nonetheless, our results suggest that TGIP does occur in invertebrates, whilst providing some potential avenues to examine the factors that account for variation in effect sizes.
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Affiliation(s)
- Nicola-Anne J Rutkowski
- School of BioSciences, University of Melbourne, Biosciences 4, Royal Parade, Parkville, VIC, 3052, Australia
| | - Kathryn B McNamara
- School of BioSciences, University of Melbourne, Biosciences 4, Royal Parade, Parkville, VIC, 3052, Australia
| | - Therésa M Jones
- School of BioSciences, University of Melbourne, Biosciences 4, Royal Parade, Parkville, VIC, 3052, Australia
| | - Yong Zhi Foo
- Centre for Evolutionary Biology & School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
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Li Y, Li P, Zhang W, Zheng X, Gu Q. New Wine in Old Bottle: Caenorhabditis Elegans in Food Science. FOOD REVIEWS INTERNATIONAL 2023. [DOI: 10.1080/87559129.2023.2172429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- Yonglu Li
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People’s Republic of China
| | - Ping Li
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People’s Republic of China
| | - Weixi Zhang
- Department of Food Science and Nutrition; Zhejiang Key Laboratory for Agro-food Processing; Fuli Institute of Food Science; National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, People’s Republic of China
| | - Xiaodong Zheng
- Department of Food Science and Nutrition; Zhejiang Key Laboratory for Agro-food Processing; Fuli Institute of Food Science; National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, People’s Republic of China
| | - Qing Gu
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, People’s Republic of China
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Fujii C, Wang D. Novel insights into virus–host interactions using the model organism C. elegans. Adv Virus Res 2023; 115:135-158. [PMID: 37173064 DOI: 10.1016/bs.aivir.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
Viruses continue to pose a public health threat raising the need for effective management strategies. Currently existing antiviral therapeutics are often specific to only a single viral species, and resistance to the therapeutic can often arise, and therefore new therapeutics are needed. The C. elegans-Orsay virus system offers a powerful platform for studying RNA virus-host interactions that could ultimately lead to novel targets for antiviral therapy. The relative simplicity of C. elegans, the well-established experimental tools, and its extensive evolutionary conservation of genes and pathways with mammals are key features of this model. Orsay virus, a bisegmented positive sense RNA virus, is a natural pathogen of C. elegans. Orsay virus infection can be studied in a multicellular organismal context, overcoming some of the limitations inherent to tissue culture-based systems. Moreover, compared to mice, the rapid generation time of C. elegans enables robust and facile forward genetics. This review aims to summarize studies that have laid the foundation for the C. elegans-Orsay virus experimental system, experimental tools, and key examples of C. elegans host factors that impact Orsay virus infection that have evolutionarily conserved function in mammalian virus infection.
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Juliane Veigl S. Do heritable immune responses extend physiological individuality? HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES 2022; 44:67. [PMID: 36427106 PMCID: PMC9700645 DOI: 10.1007/s40656-022-00549-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Immunology and its philosophy are a primary source for thinking about biological individuality. Through its discriminatory function, the immune system is believed to delineate organism and environment within one generation, thus defining the physiological individual. Based on the paradigmatic instantiations of immune systems, immune interactions and, thus, the physiological individual are believed to last only for one generation. However, in recent years, transgenerationally persisting immune responses have been reported in several phyla, but the consequences for physiological individuality have not yet been explored. In this article, I will introduce an invertebrate immune system that is RNA-based and operates through a heritable silencing/licensing paradigm. I will discuss how such a perspective on immune systems can illuminate our conceptions of individuality. I will particularly introduce an account of immunological individuality that is not restricted to one generation.
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van Sluijs L, Bosman KJ, Pankok F, Blokhina T, Wilten JIHA, te Molder DM, Riksen JAG, Snoek BL, Pijlman GP, Kammenga JE, Sterken MG. Balancing Selection of the Intracellular Pathogen Response in Natural Caenorhabditis elegans Populations. Front Cell Infect Microbiol 2022; 11:758331. [PMID: 35174100 PMCID: PMC8841876 DOI: 10.3389/fcimb.2021.758331] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/21/2021] [Indexed: 12/17/2022] Open
Abstract
Genetic variation in host populations may lead to differential viral susceptibilities. Here, we investigate the role of natural genetic variation in the Intracellular Pathogen Response (IPR), an important antiviral pathway in the model organism Caenorhabditis elegans against Orsay virus (OrV). The IPR involves transcriptional activity of 80 genes including the pals-genes. 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. Genetic analysis of 330 global 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, suggesting that different evolutionary strategies exist in IPR regulation. We infected eleven C. elegans strains that represent three distinct pals-22 pals-25 haplotypes with Orsay virus to determine their susceptibility. For two of these strains, N2 and CB4856, the transcriptional response to infection was also measured. The results indicate that pals-22 pals-25 haplotype shapes the defense against OrV and host genetic variation can result in constitutive activation of IPR genes. Our work presents evidence for balancing genetic selection of immunity genes in C. elegans and provides a novel perspective on the functional diversity that can develop within a main antiviral response in natural host populations.
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Affiliation(s)
- Lisa van Sluijs
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
- Laboratory of Virology, Wageningen University and Research, Wageningen, Netherlands
| | - Kobus J. Bosman
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Frederik Pankok
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Tatiana Blokhina
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Jop I. H. A. Wilten
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Dennie M. te Molder
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Joost A. G. Riksen
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Basten L. Snoek
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Gorben P. Pijlman
- Laboratory of Virology, Wageningen University and Research, Wageningen, Netherlands
| | - Jan E. Kammenga
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Mark G. Sterken
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
- Laboratory of Virology, Wageningen University and Research, Wageningen, Netherlands
- *Correspondence: Mark G. Sterken,
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Abstract
One of the first layers of protection that metazoans put in place to defend themselves against viruses rely on the use of proteins containing DExD/H-box helicase domains. These members of the duplex RNA–activated ATPase (DRA) family act as sensors of double-stranded RNA (dsRNA) molecules, a universal marker of viral infections. DRAs can be classified into 2 subgroups based on their mode of action: They can either act directly on the dsRNA, or they can trigger a signaling cascade. In the first group, the type III ribonuclease Dicer plays a key role to activate the antiviral RNA interference (RNAi) pathway by cleaving the viral dsRNA into small interfering RNAs (siRNAs). This represents the main innate antiviral immune mechanism in arthropods and nematodes. Even though Dicer is present and functional in mammals, the second group of DRAs, containing the RIG-I-like RNA helicases, appears to have functionally replaced RNAi and activate type I interferon (IFN) response upon dsRNA sensing. However, recent findings tend to blur the frontier between these 2 mechanisms, thereby highlighting the crucial and diverse roles played by RNA helicases in antiviral innate immunity. Here, we will review our current knowledge of the importance of these key proteins in viral infection, with a special focus on the interplay between the 2 main types of response that are activated by dsRNA.
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Affiliation(s)
- Morgane Baldaccini
- Université de Strasbourg, Architecture et Réactivité de l’ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Sébastien Pfeffer
- Université de Strasbourg, Architecture et Réactivité de l’ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
- * E-mail:
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van Sluijs L, Liu J, Schrama M, van Hamond S, Vromans SPJM, Scholten MH, Žibrat N, Riksen JAG, Pijlman GP, Sterken MG, Kammenga JE. Virus infection modulates male sexual behaviour in Caenorhabditis elegans. Mol Ecol 2021; 30:6776-6790. [PMID: 34534386 PMCID: PMC9291463 DOI: 10.1111/mec.16179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 08/23/2021] [Accepted: 09/07/2021] [Indexed: 12/28/2022]
Abstract
Mating dynamics follow from natural selection on mate choice and individuals maximizing their reproductive success. Mate discrimination reveals itself by a plethora of behaviours and morphological characteristics, each of which can be affected by pathogens. A key question is how pathogens affect mate choice and outcrossing behaviour. Here we investigated the effect of Orsay virus on the mating dynamics of the androdiecious (male and hermaphrodite) nematode Caenorhabditis elegans. We tested genetically distinct strains and found that viral susceptibility differed between sexes in a genotype-dependent manner with males of reference strain N2 being more resistant than hermaphrodites. Males displayed a constitutively higher expression of intracellular pathogen response (IPR) genes, whereas the antiviral RNAi response did not have increased activity in males. Subsequent monitoring of sex ratios over 10 generations revealed that viral presence can change mating dynamics in isogenic populations. Sexual attraction assays showed that males preferred mating with uninfected rather than infected hermaphrodites. Together our results illustrate for the first time that viral infection can significantly affect male mating choice and suggest altered mating dynamics as a novel cause benefitting outcrossing under pathogenic stress conditions in C. elegans.
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Affiliation(s)
- Lisa van Sluijs
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
- Laboratory of VirologyWageningen University and ResearchWageningenthe Netherlands
| | - Jie Liu
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Mels Schrama
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Sanne van Hamond
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | | | - Marèl H. Scholten
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Nika Žibrat
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Joost A. G. Riksen
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Gorben P. Pijlman
- Laboratory of VirologyWageningen University and ResearchWageningenthe Netherlands
| | - Mark G. Sterken
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
| | - Jan E. Kammenga
- Laboratory of NematologyWageningen University and ResearchWageningenthe Netherlands
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14
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Huang Y, Sterken MG, van Zwet K, van Sluijs L, Pijlman GP, Kammenga JE. Heat Stress Reduces the Susceptibility of Caenorhabditis elegans to Orsay Virus Infection. Genes (Basel) 2021; 12:1161. [PMID: 34440335 PMCID: PMC8392475 DOI: 10.3390/genes12081161] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
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.
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Affiliation(s)
- Yuqing Huang
- Laboratory of Nematology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (Y.H.); (M.G.S.); (K.v.Z.); (L.v.S.)
| | - Mark G. Sterken
- Laboratory of Nematology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (Y.H.); (M.G.S.); (K.v.Z.); (L.v.S.)
| | - Koen van Zwet
- Laboratory of Nematology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (Y.H.); (M.G.S.); (K.v.Z.); (L.v.S.)
| | - Lisa van Sluijs
- Laboratory of Nematology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (Y.H.); (M.G.S.); (K.v.Z.); (L.v.S.)
| | - Gorben P. Pijlman
- Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands;
| | - Jan E. Kammenga
- Laboratory of Nematology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (Y.H.); (M.G.S.); (K.v.Z.); (L.v.S.)
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15
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Silva WTAF, Otto SP, Immler S. Evolution of plasticity in production and transgenerational inheritance of small RNAs under dynamic environmental conditions. PLoS Genet 2021; 17:e1009581. [PMID: 34038409 PMCID: PMC8186813 DOI: 10.1371/journal.pgen.1009581] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 06/08/2021] [Accepted: 05/05/2021] [Indexed: 01/07/2023] Open
Abstract
In a changing environment, small RNAs (sRNAs) play an important role in the post-transcriptional regulation of gene expression and can vary in abundance depending on the conditions experienced by an individual (phenotypic plasticity) and its parents (non-genetic inheritance). Many sRNAs are unusual in that they can be produced in two ways, either using genomic DNA as the template (primary sRNAs) or existing sRNAs as the template (secondary sRNAs). Thus, organisms can evolve rapid plastic responses to their current environment by adjusting the amplification rate of sRNA templates. sRNA levels can also be transmitted transgenerationally by the direct transfer of either sRNAs or the proteins involved in amplification. Theory is needed to describe the selective forces acting on sRNA levels, accounting for the dual nature of sRNAs as regulatory elements and templates for amplification and for the potential to transmit sRNAs and their amplification agents to offspring. Here, we develop a model to study the dynamics of sRNA production and inheritance in a fluctuating environment. We tested the selective advantage of mutants capable of sRNA-mediated phenotypic plasticity within resident populations with fixed levels of sRNA transcription. Even when the resident was allowed to evolve an optimal constant rate of sRNA production, plastic amplification rates capable of responding to environmental conditions were favored. Mechanisms allowing sRNA transcripts or amplification agents to be inherited were favored primarily when parents and offspring face similar environments and when selection acts before the optimal level of sRNA can be reached within the organism. Our study provides a clear set of testable predictions for the evolution of sRNA-related mechanisms of phenotypic plasticity and transgenerational inheritance.
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Affiliation(s)
| | - Sarah P. Otto
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Simone Immler
- Department of Evolutionary Biology, Uppsala University, Uppsala, Sweden
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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16
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Sterken MG, van Wijk MH, Quamme EC, Riksen JAG, Carnell L, Mathies LD, Davies AG, Kammenga JE, Bettinger JC. Transcriptional analysis of the response of C. elegans to ethanol exposure. Sci Rep 2021; 11:10993. [PMID: 34040055 PMCID: PMC8155136 DOI: 10.1038/s41598-021-90282-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 05/07/2021] [Indexed: 11/30/2022] Open
Abstract
Ethanol-induced transcriptional changes underlie important physiological responses to ethanol that are likely to contribute to the addictive properties of the drug. We examined the transcriptional responses of Caenorhabditis elegans across a timecourse of ethanol exposure, between 30 min and 8 h, to determine what genes and genetic pathways are regulated in response to ethanol in this model. We found that short exposures to ethanol (up to 2 h) induced expression of metabolic enzymes involved in metabolizing ethanol and retinol, while longer exposure (8 h) had much more profound effects on the transcriptome. Several genes that are known to be involved in the physiological response to ethanol, including direct ethanol targets, were regulated at 8 h of exposure. This longer exposure to ethanol also resulted in the regulation of genes involved in cilia function, which is consistent with an important role for the effects of ethanol on cilia in the deleterious effects of chronic ethanol consumption in humans. Finally, we found that food deprivation for an 8-h period induced gene expression changes that were somewhat ameliorated by the presence of ethanol, supporting previous observations that worms can use ethanol as a calorie source.
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Affiliation(s)
- Mark G Sterken
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Marijke H van Wijk
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Elizabeth C Quamme
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA, 23298, USA
| | - Joost A G Riksen
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Lucinda Carnell
- Department of Biological Sciences, Central Washington University, Ellensburg, WA, 98926, USA
| | - Laura D Mathies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA, 23298, USA
- Virginia Commonwealth University Alcohol Research Center, Richmond, VA, USA
| | - Andrew G Davies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA, 23298, USA
- Virginia Commonwealth University Alcohol Research Center, Richmond, VA, USA
| | - Jan E Kammenga
- Laboratory of Nematology, Wageningen University and Research, 6708 PB, Wageningen, The Netherlands
| | - Jill C Bettinger
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Box 980613, Richmond, VA, 23298, USA.
- Virginia Commonwealth University Alcohol Research Center, Richmond, VA, USA.
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17
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Sterken MG, van Sluijs L, Wang YA, Ritmahan W, Gultom ML, Riksen JAG, Volkers RJM, Snoek LB, Pijlman GP, Kammenga JE. Punctuated Loci on Chromosome IV Determine Natural Variation in Orsay Virus Susceptibility of Caenorhabditis elegans Strains Bristol N2 and Hawaiian CB4856. J Virol 2021; 95:e02430-20. [PMID: 33827942 PMCID: PMC8315983 DOI: 10.1128/jvi.02430-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/29/2021] [Indexed: 01/06/2023] Open
Abstract
Host-pathogen interactions play a major role in evolutionary selection and shape natural genetic variation. The genetically distinct Caenorhabditis elegans strains, Bristol N2 and Hawaiian CB4856, are differentially susceptible to the Orsay virus (OrV). Here, we report the dissection of the genetic architecture of susceptibility to OrV infection. We compare OrV infection in the relatively resistant wild-type CB4856 strain to the more susceptible canonical N2 strain. To gain insight into the genetic architecture of viral susceptibility, 52 fully sequenced recombinant inbred lines (CB4856 × N2 RILs) were exposed to OrV. This led to the identification of two loci on chromosome IV associated with OrV resistance. To verify the two loci and gain additional insight into the genetic architecture controlling virus infection, introgression lines (ILs) that together cover chromosome IV, were exposed to OrV. Of the 27 ILs used, 17 had an CB4856 introgression in an N2 background, and 10 had an N2 introgression in a CB4856 background. Infection of the ILs confirmed and fine-mapped the locus underlying variation in OrV susceptibility, and we found that a single nucleotide polymorphism in cul-6 may contribute to the difference in OrV susceptibility between N2 and CB4856. An allele swap experiment showed the strain CB4856 became as susceptible as the N2 strain by having an N2 cul-6 allele, although having the CB4856 cul-6 allele did not increase resistance in N2. In addition, we found that multiple strains with nonoverlapping introgressions showed a distinct infection phenotype from the parental strain, indicating that there are punctuated locations on chromosome IV determining OrV susceptibility. Thus, our findings reveal the genetic complexity of OrV susceptibility in C. elegans and suggest that viral susceptibility is governed by multiple genes.IMPORTANCE Genetic variation determines the viral susceptibility of hosts. Yet, pinpointing which genetic variants determine viral susceptibility remains challenging. Here, we have exploited the genetic tractability of the model organism Caenorhabditis elegans to dissect the genetic architecture of Orsay virus infection. Our results provide novel insight into natural determinants of Orsay virus infection.
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Affiliation(s)
- Mark G Sterken
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Lisa van Sluijs
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Yiru A Wang
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Wannisa Ritmahan
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Mitra L Gultom
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Joost A G Riksen
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Rita J M Volkers
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - L Basten Snoek
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
- Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Jan E Kammenga
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
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18
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Willis AR, Zhao W, Sukhdeo R, Wadi L, El Jarkass HT, Claycomb JM, Reinke AW. A parental transcriptional response to microsporidia infection induces inherited immunity in offspring. SCIENCE ADVANCES 2021; 7:7/19/eabf3114. [PMID: 33952520 PMCID: PMC8099193 DOI: 10.1126/sciadv.abf3114] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 03/17/2021] [Indexed: 05/05/2023]
Abstract
Parental infection can result in the production of offspring with enhanced immunity phenotypes. Critically, the mechanisms underlying inherited immunity are poorly understood. Here, we show that Caenorhabditis elegans infected with the intracellular microsporidian parasite N. parisii produce progeny that are resistant to microsporidia infection. We determine the kinetics of the response and show that intergenerational immunity prevents host-cell invasion by Nematocida parisii and enhances survival to the bacterial pathogen Pseudomonas aeruginosa We demonstrate that immunity is induced by the parental transcriptional response to infection, which can be mimicked through maternal somatic depletion of PALS-22 and the retinoblastoma protein ortholog, LIN-35. We find that other biotic and abiotic stresses (viral infection and cadmium exposure) that induce a similar transcriptional response as microsporidia also induce immunity in progeny. Together, our results reveal how a parental transcriptional signal can be induced by distinct stimuli and protect offspring against multiple classes of pathogens.
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Affiliation(s)
- Alexandra R Willis
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Winnie Zhao
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Ronesh Sukhdeo
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Lina Wadi
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | | | - Julie M Claycomb
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Aaron W Reinke
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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19
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Frolows N, Ashe A. Small RNAs and chromatin in the multigenerational epigenetic landscape of Caenorhabditis elegans. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200112. [PMID: 33866817 DOI: 10.1098/rstb.2020.0112] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
For decades, it was thought that the only heritable information transmitted from one individual to another was that encoded in the DNA sequence. However, it has become increasingly clear that this is not the case and that the transmission of molecules from within the cytoplasm of the gamete also plays a significant role in heritability. The roundworm, Caenorhabditis elegans, has emerged as one of the leading model organisms in which to study the mechanisms of transgenerational epigenetic inheritance (TEI). Collaborative efforts over the past few years have revealed that RNA molecules play a critical role in transmitting transgenerational responses, but precisely how they do so is as yet uncertain. In addition, the role of histone modifications in epigenetic inheritance is increasingly apparent, and RNA and histones interact in a way that we do not yet fully understand. Furthermore, both exogenous and endogenous RNA molecules, as well as other environmental triggers, are able to induce heritable epigenetic changes that affect transcription across the genome. In most cases, these epigenetic changes last only for a handful of generations, but occasionally can be maintained much longer: perhaps indefinitely. In this review, we discuss the current understanding of the role of RNA and histones in TEI, as well as making clear the gaps in our knowledge. We also speculate on the evolutionary implications of epigenetic inheritance, particularly in the context of a short-lived, clonally propagating species. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'
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Affiliation(s)
- Natalya Frolows
- School of Life and Environmental Sciences, University of Sydney, New South Wales, 2006, Australia.,CSIRO Health and Biosecurity, Sydney, New South Wales, 2113, Australia
| | - Alyson Ashe
- School of Life and Environmental Sciences, University of Sydney, New South Wales, 2006, Australia
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20
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Evidence For Long-Lasting Transgenerational Antiviral Immunity in Insects. Cell Rep 2020; 33:108506. [PMID: 33326778 PMCID: PMC7758158 DOI: 10.1016/j.celrep.2020.108506] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/04/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022] Open
Abstract
Transgenerational immune priming (TGIP) allows memory-like immune responses to be transmitted from parents to offspring in many invertebrates. Despite increasing evidence for TGIP in insects, the mechanisms involved in the transfer of information remain largely unknown. Here, we show that Drosophila melanogaster and Aedes aegypti transmit antiviral immunological memory to their progeny that lasts throughout generations. We observe that TGIP, which is virus and sequence specific but RNAi independent, is initiated by a single exposure to disparate RNA viruses and also by inoculation of a fragment of viral double-stranded RNA. The progeny, which inherit a viral DNA that is only a fragment of the viral RNA used to infect the parents, display enriched expression of genes related to chromatin and DNA binding. These findings represent a demonstration of TGIP for RNA viruses in invertebrates, broadly increasing our understanding of the immune response, host genome plasticity, and antiviral memory of the germline.
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21
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Willis AR, Sukhdeo R, Reinke AW. Remembering your enemies: mechanisms of within-generation and multigenerational immune priming in Caenorhabditis elegans. FEBS J 2020; 288:1759-1770. [PMID: 32767821 DOI: 10.1111/febs.15509] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/17/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022]
Abstract
Pathogens are abundant and drive evolution of host immunity. Whilst immune memory is classically associated with adaptive immunity, studies in diverse species now show that priming of innate immune defences can also protect against secondary infection. Remarkably, priming may also be passed on to progeny to enhance pathogen resistance and promote survival in future generations. Phenotypic changes that occur independent of DNA sequence underlie both 'within-generation' priming and 'multigenerational' priming. However, the molecular mechanisms responsible for these phenomena are still poorly understood. Caenorhabditis elegans is a simple and genetically tractable model organism that has enabled key advances in immunity and environmental epigenetics. Using both natural and human pathogens, researchers have uncovered numerous examples of innate immune priming in this animal. Viral infection models have provided key evidence for a conserved antiviral RNA silencing mechanism that is inherited in progeny. Bacterial infection models have explored mechanisms of within-generation and multigenerational priming that span chromatin modification and transcriptional changes, small RNA pathways, maternal provisioning and pathogen avoidance strategies. Together, these studies are providing novel insight into the immune reactivity of the genome and have important consequences for our understanding of health and evolution. In this review, we present the current evidence for learned protection against pathogens in C. elegans, discuss the significance and limitations of these findings and highlight important avenues of future investigation.
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Affiliation(s)
| | - Ronesh Sukhdeo
- Department of Molecular Genetics, University of Toronto, ON, Canada
| | - Aaron W Reinke
- Department of Molecular Genetics, University of Toronto, ON, Canada
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22
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Genetic Variation in Complex Traits in Transgenic α-Synuclein Strains of Caenorhabditis elegans. Genes (Basel) 2020; 11:genes11070778. [PMID: 32664512 PMCID: PMC7397059 DOI: 10.3390/genes11070778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 11/16/2022] Open
Abstract
Different genetic backgrounds can modify the effect of mutated genes. Human α-synuclein (SNCA) gene encodes α-synuclein, and its oligomeric complexes accumulate with age and mediate the disruption of cellular homeostasis, resulting in the neuronal death that is characteristic of Parkinson’s Disease. Polymorphic variants modulate this complex pathologic mechanism. Previously, we constructed five transgenic introgression lines of a Caenorhabditis elegans model of α-synuclein using genetic backgrounds that are genetically diverse from the canonical wild-type Bristol N2. A gene expression analysis revealed that the α-synuclein transgene differentially affects genome-wide transcription due to background modifiers. To further investigate how complex traits are affected in these transgenic lines, we measured the α-synuclein transgene expression, the overall accumulation of the fusion protein of α-synuclein and yellow fluorescent protein (YFP), the lysosome-related organelles, and the body size. By using quantitative PCR (qPCR), we demonstrated stable and similar expression levels of the α-synuclein transgene in different genetic backgrounds. Strikingly, we observed that the levels of the a-synuclein:YFP fusion protein vary in different genetic backgrounds by using the COPAS™ biosorter. The quantification of the Nile Red staining assay demonstrates that α-synuclein also affects lysosome-related organelles and body size. Our results show that the same α-synuclein introgression in different C. elegans backgrounds can produces differing effects on complex traits due to background modifiers.
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23
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Huang Y, Kammenga JE. Genetic Variation in Caenorhabditis elegans Responses to Pathogenic Microbiota. Microorganisms 2020; 8:E618. [PMID: 32344661 PMCID: PMC7232262 DOI: 10.3390/microorganisms8040618] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 12/30/2022] Open
Abstract
The bacterivorous nematode Caenorhabditis elegans is an important model species for understanding genetic variation of complex traits. So far, most studies involve axenic laboratory settings using Escherichia coli as the sole bacterial species. Over the past decade, however, investigations into the genetic variation of responses to pathogenic microbiota have increasingly received attention. Quantitative genetic analyses have revealed detailed insight into loci, genetic variants, and pathways in C. elegans underlying interactions with bacteria, microsporidia, and viruses. As various quantitative genetic platforms and resources like C. elegans Natural Diversity Resource (CeNDR) and Worm Quantitative Trait Loci (WormQTL) have been developed, we anticipate that expanding C. elegans research along the lines of genetic variation will be a treasure trove for opening up new insights into genetic pathways and gene functionality of microbiota interactions.
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Affiliation(s)
| | - Jan E. Kammenga
- Laboratory of Nematology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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24
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Abstract
Caenorhabditis elegans has long been a laboratory model organism with no known natural pathogens. In the past ten years, however, natural viruses have been isolated from wild-caught C. elegans (Orsay virus) and its relative Caenorhabditis briggsae (Santeuil virus, Le Blanc virus, and Melnik virus). All are RNA positive-sense viruses related to Nodaviridae; they infect intestinal cells and are horizontally transmitted. The Orsay virus capsid structure has been determined and the virus can be reconstituted by transgenesis of the host. Recent use of the Orsay virus has enabled researchers to identify evolutionarily conserved proviral and antiviral genes that function in nematodes and mammals. These pathways include endocytosis through SID-3 and WASP; a uridylyltransferase that destabilizes viral RNAs by uridylation of their 3′ end; ubiquitin protein modifications and turnover; and the RNA interference pathway, which recognizes and degrades viral RNA.
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Affiliation(s)
- Marie-Anne Félix
- Institute of Biology of the École Normale Supérieure, CNRS UMR8197, INSERM U1024, 75230 Paris CEDEX 05, France
| | - David Wang
- Departments of Molecular Microbiology and Pathology & Immunology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA
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25
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Tetreau G, Dhinaut J, Gourbal B, Moret Y. Trans-generational Immune Priming in Invertebrates: Current Knowledge and Future Prospects. Front Immunol 2019; 10:1938. [PMID: 31475001 PMCID: PMC6703094 DOI: 10.3389/fimmu.2019.01938] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/30/2019] [Indexed: 01/15/2023] Open
Abstract
Trans-generational immune priming (TGIP) refers to the transfer of the parental immunological experience to its progeny. This may result in offspring protection from repeated encounters with pathogens that persist across generations. Although extensively studied in vertebrates for over a century, this phenomenon has only been identified 20 years ago in invertebrates. Since then, invertebrate TGIP has been the focus of an increasing interest, with half of studies published during the last few years. TGIP has now been tested in several invertebrate systems using various experimental approaches and measures to study it at both functional and evolutionary levels. However, drawing an overall picture of TGIP from available studies still appears to be a difficult task. Here, we provide a comprehensive review of TGIP in invertebrates with the objective of confronting all the data generated to date to highlight the main features and mechanisms identified in the context of its ecology and evolution. To this purpose, we describe all the articles reporting experimental investigation of TGIP in invertebrates and propose a critical analysis of the experimental procedures performed to study this phenomenon. We then investigate the outcome of TGIP in the offspring and its ecological and evolutionary relevance before reviewing the potential molecular mechanisms identified to date. In the light of this review, we build hypothetical scenarios of the mechanisms through which TGIP might be achieved and propose guidelines for future investigations.
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Affiliation(s)
- Guillaume Tetreau
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
- Université Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Julien Dhinaut
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France
| | - Benjamin Gourbal
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Yannick Moret
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France
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26
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Rechavi O, Lev I. Principles of Transgenerational Small RNA Inheritance in Caenorhabditis elegans. Curr Biol 2018; 27:R720-R730. [PMID: 28743023 DOI: 10.1016/j.cub.2017.05.043] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Examples of transgenerational inheritance of environmental responses are rapidly accumulating. In Caenorhabditis elegans nematodes, such heritable information transmits across generations in the form of RNA-dependent RNA polymerase-amplified small RNAs. Regulatory small RNAs enable sequence-specific gene regulation, and unlike chromatin modifications, can move between tissues, and escape from immediate germline reprogramming. In this review, we discuss the path that small RNAs take from the soma to the germline, and elaborate on the mechanisms that maintain or erase parental small RNA responses after a specific number of generations. We focus on the intricate interactions between heritable small RNAs and histone modifications, deposited on specific loci. A trace of heritable chromatin marks, in particular trimethylation of histone H3 lysine 9, is deposited on RNAi-targeted loci. However, how these modifications regulate RNAi or small RNA inheritance was until recently unclear. Integrating the very latest literature, we suggest that changes to histone marks may instigate transgenerational gene regulation indirectly, by affecting the biogenesis of heritable small RNAs. Inheritance of small RNAs could spread adaptive ancestral responses.
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Affiliation(s)
- Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School for Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
| | - Itamar Lev
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School for Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
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27
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Serrato-Salas J, Izquierdo-Sánchez J, Argüello M, Conde R, Alvarado-Delgado A, Lanz-Mendoza H. Aedes aegypti antiviral adaptive response against DENV-2. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 84:28-36. [PMID: 29408269 DOI: 10.1016/j.dci.2018.01.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 01/30/2018] [Accepted: 01/31/2018] [Indexed: 06/07/2023]
Abstract
Priming is the conceptual term defining memory phenomenon in innate immune response. Numerous examples of enhanced secondary immune response have been described in diverse taxa of invertebrates; which naturally lacks memory response. In mosquitoes, a previous non-lethal challenge with some specific pathogens modify their immune response against the same microorganism; developing an improved antimicrobial reaction. In this work, we explore the ability of Aedes aegypti to mount a higher antiviral response upon a second oral DENV challenge. When previously challenged with inactive virus, we observed that the posterior infection showed a diminished number of DENV infectious particles in midguts and carcasses. In challenged tissues, we detected higher de novo midgut DNA synthesis than control group, as determined by DNA incorporation of 5-bromo-2-deoxyuridine. We demonstrated that inactive DENV particle are capable to induce DNA synthesis levels comparable to infective DENV. We considered the Drosophila melanogaster hindsight and Delta-Notch mosquitoes orthologues as potential de novo DNA synthesis pathway components (as observed in fly oocyte development and midgut tissue renewal). We showed that Aedes aegypti hindsight transcript relative expression levels were higher than control during DENV infection and inactive DENV particle alimentation. Also, Aedes aegypti second challenge with active DENV induced higher hindsight, Delta and Notch transcriptions in the primed mosquitoes (compared with the primary infection levels). Considering that the mosquito de novo DNA synthesis is concomitant to viral particle reduction, this finding opens a new perspective on the mechanisms underlying the vector antiviral immune response and the effector molecules involved.
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Affiliation(s)
- Javier Serrato-Salas
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico
| | - Javier Izquierdo-Sánchez
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico
| | - Martha Argüello
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico
| | - Renáud Conde
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico
| | - Alejandro Alvarado-Delgado
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico
| | - Humberto Lanz-Mendoza
- Centro de Investigaciones sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, CP 62100, Cuernavaca, Morelos, Mexico.
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Recent advances in vertebrate and invertebrate transgenerational immunity in the light of ecology and evolution. Heredity (Edinb) 2018; 121:225-238. [PMID: 29915335 DOI: 10.1038/s41437-018-0101-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 05/06/2018] [Accepted: 05/31/2018] [Indexed: 12/18/2022] Open
Abstract
Parental experience with parasites and pathogens can lead to increased offspring resistance to infection, through a process known as transgenerational immune priming (TGIP). Broadly defined, TGIP occurs across a wide range of taxa, and can be viewed as a type of phenotypic plasticity, with hosts responding to the pressures of relevant local infection risk by altering their offspring's immune defenses. There are ever increasing examples of both invertebrate and vertebrate TGIP, which go beyond classical examples of maternal antibody transfer. Here we critically summarize the current evidence for TGIP in both invertebrates and vertebrates. Mechanisms underlying TGIP remain elusive in many systems, but while it is unlikely that they are conserved across the range of organisms with TGIP, recent insight into epigenetic modulation may challenge this view. We place TGIP into a framework of evolutionary ecology, discussing costs and relevant environmental variation. We highlight how the ecology of species or populations should affect if, where, when, and how TGIP is realized. We propose that the field can progress by incorporating evolutionary ecology focused designs to the study of the so far well chronicled, but mostly descriptive TGIP, and how rapidly developing -omic methods can be employed to further understand TGIP across taxa.
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GIBSON AMANDAK, MORRAN LEVIT. A Model for Evolutionary Ecology of Disease: The Case for Caenorhabditis Nematodes and Their Natural Parasites. J Nematol 2018. [DOI: 10.21307/jofnem-2017-083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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30
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Abstract
Since 1999, Caenorhabditis elegans has been extensively used to study microbe-host interactions due to its simple culture, genetic tractability, and susceptibility to numerous bacterial and fungal pathogens. In contrast, virus studies have been hampered by a lack of convenient virus infection models in nematodes. The recent discovery of a natural viral pathogen of C. elegans and development of diverse artificial infection models are providing new opportunities to explore virus-host interplay in this powerful model organism.
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Affiliation(s)
- Don B Gammon
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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31
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Gibson AK, Morran LT. A Model for Evolutionary Ecology of Disease: The Case for Caenorhabditis Nematodes and Their Natural Parasites. J Nematol 2017; 49:357-372. [PMID: 29353923 PMCID: PMC5770282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Indexed: 06/07/2023] Open
Abstract
Many of the outstanding questions in disease ecology and evolution call for combining observation of natural host-parasite populations with experimental dissection of interactions in the field and the laboratory. The "rewilding" of model systems holds great promise for this endeavor. Here, we highlight the potential for development of the nematode Caenorhabditis elegans and its close relatives as a model for the study of disease ecology and evolution. This powerful laboratory model was disassociated from its natural habitat in the 1960s. Today, studies are uncovering that lost natural history, with several natural parasites described since 2008. Studies of these natural Caenorhabditis-parasite interactions can reap the benefits of the vast array of experimental and genetic tools developed for this laboratory model. In this review, we introduce the natural parasites of C. elegans characterized thus far and discuss resources available to study them, including experimental (co)evolution, cryopreservation, behavioral assays, and genomic tools. Throughout, we present avenues of research that are interesting and feasible to address with caenorhabditid nematodes and their natural parasites, ranging from the maintenance of outcrossing to the community dynamics of host-associated microbes. In combining natural relevance with the experimental power of a laboratory supermodel, these fledgling host-parasite systems can take on fundamental questions in evolutionary ecology of disease.
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Affiliation(s)
| | - Levi T Morran
- Department of Biology, Emory University, Atlanta, GA 30322
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32
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van Sluijs L, Pijlman GP, Kammenga JE. Why do Individuals Differ in Viral Susceptibility? A Story Told by Model Organisms. Viruses 2017; 9:E284. [PMID: 28973976 PMCID: PMC5691635 DOI: 10.3390/v9100284] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 01/30/2023] Open
Abstract
Viral susceptibility and disease progression is determined by host genetic variation that underlies individual differences. Genetic polymorphisms that affect the phenotype upon infection have been well-studied for only a few viruses, such as HIV-1 and Hepatitis C virus. However, even for well-studied viruses the genetic basis of individual susceptibility differences remains elusive. Investigating the effect of causal polymorphisms in humans is complicated, because genetic methods to detect rare or small-effect polymorphisms are limited and genetic manipulation is not possible in human populations. Model organisms have proven a powerful experimental platform to identify and characterize polymorphisms that underlie natural variations in viral susceptibility using quantitative genetic tools. We summarize and compare the genetic tools available in three main model organisms, Mus musculus, Drosophila melanogaster, and Caenorhabditis elegans, and illustrate how these tools can be applied to detect polymorphisms that determine the viral susceptibility. Finally, we analyse how candidate polymorphisms from model organisms can be used to shed light on the underlying mechanism of individual variation. Insights in causal polymorphisms and mechanisms underlying individual differences in viral susceptibility in model organisms likely provide a better understanding in humans.
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Affiliation(s)
- Lisa van Sluijs
- Laboratory of Nematology, Wageningen University, 6708 PB Wageningen, The Netherlands.
- Laboratory of Virology, Wageningen University, 6708 PB Wageningen, The Netherlands.
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, 6708 PB Wageningen, The Netherlands.
| | - Jan E Kammenga
- Laboratory of Nematology, Wageningen University, 6708 PB Wageningen, The Netherlands.
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An evolutionarily conserved transcriptional response to viral infection in Caenorhabditis nematodes. BMC Genomics 2017; 18:303. [PMID: 28415971 PMCID: PMC5392922 DOI: 10.1186/s12864-017-3689-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/07/2017] [Indexed: 12/27/2022] Open
Abstract
Background Caenorhabditis elegans is a powerful model organism for probing many biological processes including host-pathogen interactions with bacteria and fungi. The recent identification of nematode viruses that naturally infect C. elegans and Caenorhabditis briggsae provides a unique opportunity to define host-virus interactions in these model hosts. Results We analyzed the transcriptional response of pathogen infected C. elegans and C. briggsae by RNA-seq. We identified a total of 320 differentially expressed genes (DEGs) in C. elegans following Orsay virus infection. The DEGs of known function were enriched for ubiquitin ligase related genes; however, the majority of the genes were of unknown function. Interestingly, many DEGs that responded to Orsay virus infection were similar to those induced by Nematocida parisii infection, which is a natural microsporidia pathogen of C. elegans that like Orsay virus infects intestinal cells. Furthermore, comparison of the Orsay virus DEGs in C. elegans to Santeuil virus DEGs in C. briggsae identified 58 C. elegans genes whose orthologs were likewise differentially expressed in C. briggsae, thereby defining an evolutionarily conserved response to viral infection. Conclusions The two different species C. elegans and C. briggsae, which diverged ~18 million years ago, share a common set of transcriptionally responsive genes to viral infection. Furthermore, a subset of these genes were also differentially expressed following infection by a eukaryotic pathogen, N. parisii, suggesting that these genes may constitute a broader pan-microbial response to infection. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3689-3) contains supplementary material, which is available to authorized users.
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Gammon DB, Ishidate T, Li L, Gu W, Silverman N, Mello CC. The Antiviral RNA Interference Response Provides Resistance to Lethal Arbovirus Infection and Vertical Transmission in Caenorhabditis elegans. Curr Biol 2017; 27:795-806. [PMID: 28262484 DOI: 10.1016/j.cub.2017.02.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/18/2017] [Accepted: 02/01/2017] [Indexed: 11/18/2022]
Abstract
The recent discovery of the positive-sense single-stranded RNA (ssRNA) Orsay virus (OV) as a natural pathogen of the nematode Caenorhabditis elegans has stimulated interest in exploring virus-nematode interactions. However, OV infection is restricted to a small number of intestinal cells, even in nematodes defective in their antiviral RNA interference (RNAi) response, and is neither lethal nor vertically transmitted. Using a fluorescent reporter strain of the negative-sense ssRNA vesicular stomatitis virus (VSV), we show that microinjection of VSV particles leads to a dose-dependent, muscle tissue-tropic, lethal infection in C. elegans. Furthermore, we find nematodes deficient for components of the antiviral RNAi pathway, such as Dicer-related helicase 1 (DRH-1), to display hypersusceptibility to VSV infection as evidenced by elevated infection rates, virus replication in multiple tissue types, and earlier mortality. Strikingly, infection of oocytes and embryos could also be observed in drh-1 mutants. Our results suggest that the antiviral RNAi response not only inhibits vertical VSV transmission but also promotes transgenerational inheritance of antiviral immunity. Our study introduces a new, in vivo virus-host model system for exploring arbovirus pathogenesis and provides the first evidence for vertical pathogen transmission in C. elegans.
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Affiliation(s)
- Don B Gammon
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Takao Ishidate
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Lichao Li
- Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, CA 92521, USA
| | - Weifeng Gu
- Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, CA 92521, USA
| | - Neal Silverman
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Craig C Mello
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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Milutinović B, Kurtz J. Immune memory in invertebrates. Semin Immunol 2016; 28:328-42. [PMID: 27402055 DOI: 10.1016/j.smim.2016.05.004] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/11/2016] [Accepted: 05/17/2016] [Indexed: 12/21/2022]
Abstract
Evidence for innate immune memory (or 'priming') in invertebrates has been accumulating over the last years. We here provide an in-depth review of the current state of evidence for immune memory in invertebrates, and in particular take a phylogenetic viewpoint. Invertebrates are a very heterogeneous group of animals and accordingly, evidence for the phenomenon of immune memory as well as the hypothesized molecular underpinnings differ largely for the diverse invertebrate taxa. The majority of research currently focuses on Arthropods, while evidence from many other groups of invertebrates is fragmentary or even lacking. We here concentrate on immune memory that is induced by pathogenic challenges, but also extent our view to a non-pathogenic context, i.e. allograft rejection, which can also show forms of memory and can inform us about general principles of specific self-nonself recognition. We discuss definitions of immune memory and a number of relevant aspects such as the type of antigens used, the route of exposure, and the kinetics of reactions following priming.
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Affiliation(s)
- Barbara Milutinović
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
| | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149 Münster, Germany.
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36
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Antiviral RNA Interference against Orsay Virus Is neither Systemic nor Transgenerational in Caenorhabditis elegans. J Virol 2015; 89:12035-46. [PMID: 26401037 PMCID: PMC4645334 DOI: 10.1128/jvi.03664-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/28/2015] [Indexed: 02/06/2023] Open
Abstract
Antiviral RNA-mediated silencing (RNA interference [RNAi]) acts as a powerful innate immunity defense in plants, invertebrates, and mammals. In Caenorhabditis elegans, RNAi is systemic; i.e., RNAi silencing signals can move between cells and tissues. Furthermore, RNAi effects can be inherited transgenerationally and may last for many generations. Neither the biological relevance of systemic RNAi nor transgenerational RNAi is currently understood. Here we examined the role of both pathways in the protection of C. elegans from viral infection. We studied the Orsay virus, a positive-strand RNA virus related to Nodaviridae and the first and only virus known to infect C. elegans. Immunity to Orsay virus infection requires the RNAi pathway. Surprisingly, we found that genes required for systemic or transgenerational RNAi did not have a role in antiviral defense. Furthermore, we found that Orsay virus infection did not elicit a systemic RNAi response even when a target for RNAi was provided by using transgenes. Finally, we show that viral siRNAs, the effectors of RNAi, are not inherited to a level that provides any significant resistance to viral infection in the next generation. We conclude that systemic or transgenerational RNAi does not play a role in the defense against natural Orsay virus infection. Furthermore, our data suggest that there is a qualitative difference between experimental RNAi and antiviral RNAi. Our data are consistent with a model of systemic and transgenerational RNAi that requires a nuclear or germ line component that is lacking in almost all RNA virus infections. IMPORTANCE Since its discovery in Caenorhabditis elegans, RNAi has proven a valuable scientific tool in many organisms. In C. elegans, exogenous RNAi spreads throughout the organism and can be passed between generations; however, there has been controversy as to the endogenous role(s) that the RNAi pathway plays. One endogenous role for which spreading both within the infected organism and between generations would be advantageous is a role in viral defense. In plants, antiviral RNAi is systemic and the spread of RNAi between cells provides protection against subsequent viral infection. Here we investigated this by using the only naturally occurring virus known to infect C. elegans, Orsay virus, and surprisingly found that, in contrast to the exogenous RNAi pathway, the antiviral RNAi response targeted against this virus does not spread systemically throughout the organism and cannot be passed between generations. These results suggest that there are differences between the two pathways that remain to be discovered.
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37
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Jose AM. Movement of regulatory RNA between animal cells. Genesis 2015; 53:395-416. [PMID: 26138457 PMCID: PMC4915348 DOI: 10.1002/dvg.22871] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 06/28/2015] [Accepted: 06/29/2015] [Indexed: 12/12/2022]
Abstract
Recent studies suggest that RNA can move from one cell to another and regulate genes through specific base-pairing. Mechanisms that modify or select RNA for secretion from a cell are unclear. Secreted RNA can be stable enough to be detected in the extracellular environment and can enter the cytosol of distant cells to regulate genes. Mechanisms that import RNA into the cytosol of an animal cell can enable uptake of RNA from many sources including other organisms. This role of RNA is akin to that of steroid hormones, which cross cell membranes to regulate genes. The potential diagnostic use of RNA in human extracellular fluids has ignited interest in understanding mechanisms that enable the movement of RNA between animal cells. Genetic model systems will be essential to gain more confidence in proposed mechanisms of RNA transport and to connect an extracellular RNA with a specific biological function. Studies in the worm C. elegans and in other animals have begun to reveal parts of this novel mechanism of cell-to-cell communication. Here, I summarize the current state of this nascent field, highlight the many unknowns, and suggest future directions.
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Affiliation(s)
- Antony M Jose
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland
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38
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Anava S, Posner R, Rechavi O. The soft genome. WORM 2015; 3:e989798. [PMID: 26430554 DOI: 10.4161/21624054.2014.989798] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 11/14/2014] [Indexed: 11/19/2022]
Abstract
Caenorhabditis elegans (C. elegans) nematodes transmit small RNAs across generations, a process that enables transgenerational regulation of genes. In contrast to changes to the DNA sequence, transgenerational transmission of small RNA-mediated responses is reversible, and thus enables "soft" or "flexible" inheritance of acquired characteristics. Until very recently only introduction of foreign genetic material (viruses, transposons, transgenes) was shown to directly lead to inheritance of small RNAs. New discoveries however, demonstrate that starvation also triggers inheritance of endogenous small RNAs in C.elegans. Multiple generations of worms inherit starvation-responsive endogenous small RNAs, and starvation also results in heritable extension of the progeny's lifespan. In this Commentary paper we explore the intriguing possibility that large parts of the genome and many additional traits are similarly subjected to heritable small RNA-mediated regulation, and focus on the potential influence of transgenerational RNAi on the worm's physiology. While the universal relevance of this mechanism remains to be discovered, we will examine how the discoveries made in worms already challenge long held dogmas in genetics and evolution.
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Affiliation(s)
- Sarit Anava
- Department of Neurobiology; Wise Faculty of Life Sciences & Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv, Israel
| | - Rachel Posner
- Department of Neurobiology; Wise Faculty of Life Sciences & Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv, Israel
| | - Oded Rechavi
- Department of Neurobiology; Wise Faculty of Life Sciences & Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv, Israel
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39
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Sela M, Kloog Y, Rechavi O. Non-coding RNAs as the bridge between epigenetic mechanisms, lineages and domains of life. J Physiol 2015; 592:2369-73. [PMID: 24882818 DOI: 10.1113/jphysiol.2014.273045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Many cases of heritable environmental responses have been documented but the underlying mechanisms are largely unknown. Recently, inherited RNA interference has been shown to act as a multigenerational genome surveillance apparatus. We suggest that inheritance of regulatory RNAs is at the root of many other epigenetic phenomena, the trigger that induces other epigenetic mechanisms, such as the depositing of histone modifications and DNA methylation. In addition, we explore the possibility that interacting organisms influence each other's transcriptomes by exchanging heterologous non-coding RNAs.
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Affiliation(s)
- Mor Sela
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 64332, Israel
| | - Yoel Kloog
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 64332, Israel
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 64332, Israel
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40
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Rechavi O, Houri-Ze'evi L, Anava S, Goh WSS, Kerk SY, Hannon GJ, Hobert O. Starvation-induced transgenerational inheritance of small RNAs in C. elegans. Cell 2014; 158:277-287. [PMID: 25018105 PMCID: PMC4377509 DOI: 10.1016/j.cell.2014.06.020] [Citation(s) in RCA: 330] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 05/30/2014] [Accepted: 06/11/2014] [Indexed: 01/03/2023]
Abstract
Evidence from animal studies and human famines suggests that starvation may affect the health of the progeny of famished individuals. However, it is not clear whether starvation affects only immediate offspring or has lasting effects; it is also unclear how such epigenetic information is inherited. Small RNA-induced gene silencing can persist over several generations via transgenerationally inherited small RNA molecules in C. elegans, but all known transgenerational silencing responses are directed against foreign DNA introduced into the organism. We found that starvation-induced developmental arrest, a natural and drastic environmental change, leads to the generation of small RNAs that are inherited through at least three consecutive generations. These small, endogenous, transgenerationally transmitted RNAs target genes with roles in nutrition. We defined genes that are essential for this multigenerational effect. Moreover, we show that the F3 offspring of starved animals show an increased lifespan, corroborating the notion of a transgenerational memory of past conditions.
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Affiliation(s)
- Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel; Columbia University Medical Center, Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, New York, NY 10032, USA.
| | - Leah Houri-Ze'evi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Sarit Anava
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Wee Siong Sho Goh
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, Howard Hughes Medical Institute, New York 11724, USA
| | - Sze Yen Kerk
- Columbia University Medical Center, Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, New York, NY 10032, USA
| | - Gregory J Hannon
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, Howard Hughes Medical Institute, New York 11724, USA
| | - Oliver Hobert
- Columbia University Medical Center, Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, New York, NY 10032, USA
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41
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Pijlman GP. Flavivirus RNAi suppression: decoding non-coding RNA. Curr Opin Virol 2014; 7:55-60. [PMID: 24793201 DOI: 10.1016/j.coviro.2014.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 04/03/2014] [Accepted: 04/06/2014] [Indexed: 12/23/2022]
Abstract
Flaviviruses are important human pathogens that are transmitted by invertebrate vectors, mostly mosquitoes and ticks. During replication in their vector, flaviviruses are subject to a potent innate immune response known as antiviral RNA interference (RNAi). This defense mechanism is associated with the production of small interfering (si)RNA that lead to degradation of viral RNA. To what extent flaviviruses would benefit from counteracting antiviral RNAi is subject of debate. Here, the experimental evidence to suggest the existence of flavivirus RNAi suppressors is discussed. I will highlight the putative role of non-coding, subgenomic flavivirus RNA in suppression of RNAi in insect and mammalian cells. Novel insights from ongoing research will reveal how arthropod-borne viruses modulate innate immunity including antiviral RNAi.
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Affiliation(s)
- Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, Wageningen 6708PB, The Netherlands.
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