1
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Romoli O, Henrion-Lacritick A, Blanc H, Frangeul L, Saleh MC. Limitations in harnessing oral RNA interference as an antiviral strategy in Aedes aegypti. iScience 2024; 27:109261. [PMID: 38433898 PMCID: PMC10907830 DOI: 10.1016/j.isci.2024.109261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/09/2024] [Accepted: 02/14/2024] [Indexed: 03/05/2024] Open
Abstract
Mosquitoes, particularly Aedes aegypti, are critical vectors for globally significant pathogenic viruses. This study examines the limitations of oral RNA interference (RNAi) as a strategy to disrupt viral transmission by Ae. aegypti. We hypothesized that double-stranded RNA (dsRNA) targeting the Zika virus (ZIKV) or chikungunya virus (CHIKV) genomes produced by engineered bacterial symbionts could trigger an antiviral response. Mosquitoes mono-colonized with Escherichia coli producing dsZIK or dsCHIK did not display reduced viral titers following exposure to virus-contaminated bloodmeals and failed to generate dsZIK- or dsCHIK-derived small interfering RNAs. To address potential limitations of bacterial dsRNA release, we explored dsRNA inoculation via feeding and injection. Although viral replication was impeded in mosquitoes injected with dsZIK or dsCHIK, no antiviral effect was observed in dsRNA-fed mosquitoes. These findings highlight complexities of implementing oral RNAi as an antiviral strategy in Ae. aegypti and warrant further exploration of local and systemic RNAi mechanisms.
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Affiliation(s)
- Ottavia Romoli
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNAi Unit, F-75015 Paris, France
| | | | - Hervé Blanc
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNAi Unit, F-75015 Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNAi Unit, F-75015 Paris, France
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNAi Unit, F-75015 Paris, France
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2
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Koh C, Saleh MC. Mosquito core viromes: do they exist? Trends Parasitol 2024; 40:203-204. [PMID: 38267279 DOI: 10.1016/j.pt.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/26/2024]
Affiliation(s)
- Cassandra Koh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
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3
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Dabo S, Henrion-Lacritick A, Lecuyer A, Jiolle D, Paupy C, Ayala D, da Veiga Leal S, Badolo A, Vega-Rúa A, Sylla M, Akorli J, Otoo S, Lutomiah J, Sang R, Mutebi JP, Saleh MC, Rose NH, McBride CS, Lambrechts L. Extensive variation and strain-specificity in dengue virus susceptibility among African Aedes aegypti populations. PLoS Negl Trop Dis 2024; 18:e0011862. [PMID: 38527081 PMCID: PMC10994562 DOI: 10.1371/journal.pntd.0011862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/04/2024] [Accepted: 03/15/2024] [Indexed: 03/27/2024] Open
Abstract
African populations of the mosquito Aedes aegypti are usually considered less susceptible to infection by human-pathogenic flaviviruses than globally invasive populations found outside Africa. Although this contrast has been well documented for Zika virus (ZIKV), it is unclear to what extent it is true for dengue virus (DENV), the most prevalent flavivirus of humans. Addressing this question is complicated by substantial genetic diversity among DENV strains, most notably in the form of four genetic types (DENV1 to DENV4), that can lead to genetically specific interactions with mosquito populations. Here, we carried out a survey of DENV susceptibility using a panel of seven field-derived Ae. aegypti colonies from across the African range of the species and a colony from Guadeloupe, French West Indies as non-African reference. We found considerable variation in the ability of African Ae. aegypti populations to acquire and replicate a panel of six DENV strains spanning the four DENV types. Although African Ae. aegypti populations were generally less susceptible than the reference non-African population from Guadeloupe, in several instances some African populations were equally or more susceptible than the Guadeloupe population. Moreover, the relative level of susceptibility between African mosquito populations depended on the DENV strain, indicating genetically specific interactions. We conclude that unlike ZIKV susceptibility, there is no clear-cut dichotomy in DENV susceptibility between African and non-African Ae. aegypti. DENV susceptibility of African Ae. aegypti populations is highly heterogeneous and largely governed by the specific pairing of mosquito population and DENV strain.
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Affiliation(s)
- Stéphanie Dabo
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
| | | | - Alicia Lecuyer
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
| | - Davy Jiolle
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Christophe Paupy
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Diego Ayala
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Silvânia da Veiga Leal
- Laboratório de Entomologia Médica, Instituto Nacional de Saúde Pública, Praia, Cabo Verde
| | - Athanase Badolo
- Laboratoire d’Entomologie Fondamentale et Appliquée, Université Joseph Ki-Zerbo, Ouagadougou, Burkina Faso
| | - Anubis Vega-Rúa
- Institut Pasteur of Guadeloupe, Laboratory of Vector Control Research, Transmission Reservoir and Pathogens Diversity Unit, Morne Jolivière, Guadeloupe, France
| | - Massamba Sylla
- Department of Livestock Sciences and Techniques, University Sine Saloum El Hadji Ibrahima NIASS, Kaffrine, Senegal
| | - Jewelna Akorli
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Sampson Otoo
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joel Lutomiah
- Arbovirus/Viral Hemorrhagic Fevers Laboratory, Center for Virus Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Rosemary Sang
- Arbovirus/Viral Hemorrhagic Fevers Laboratory, Center for Virus Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - John-Paul Mutebi
- Department of Solid Waste Management, Mosquito Control Division, Miami, Florida, United States of America
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, Paris, France
| | - Noah H. Rose
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Carolyn S. McBride
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Louis Lambrechts
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
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4
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Abstract
Mosquitoes are best known for transmitting human and animal viruses. However, they also harbour mosquito-specific viruses (MSVs) as part of their microbiota. These are a group of viruses whose diversity and prevalence overshadow their medically relevant counterparts. Although metagenomics sequencing has remarkably accelerated the discovery of these viruses, what we know about them is often limited to sequence information, leaving much of their fundamental biology to be explored. Understanding the biology and ecology of MSVs can enlighten our knowledge of virus-virus interactions and lead to new innovations in the management of mosquito-borne viral diseases. We retrace the history of their discovery and discuss research milestones that would line the path from mosquito virome knowledge to vector management strategies.
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Affiliation(s)
- Cassandra Koh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
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5
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Dabo S, Henrion-Lacritick A, Lecuyer A, Jiolle D, Paupy C, Ayala D, da Veiga Leal S, Badolo A, Vega-Rúa A, Sylla M, Akorli J, Otoo S, Lutomiah J, Sang R, Mutebi JP, Saleh MC, Rose NH, McBride CS, Lambrechts L. Extensive variation and strain-specificity in dengue virus susceptibility among African Aedes aegypti populations. bioRxiv 2023:2023.12.14.571617. [PMID: 38168387 PMCID: PMC10760182 DOI: 10.1101/2023.12.14.571617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
African populations of the mosquito Aedes aegypti are usually considered less susceptible to infection by human-pathogenic flaviviruses than globally invasive populations found outside Africa. Although this contrast has been well documented for Zika virus (ZIKV), it is unclear to what extent it is true for dengue virus (DENV), the most prevalent flavivirus of humans. Addressing this question is complicated by substantial genetic diversity among DENV strains, most notably in the form of four genetic types (DENV1 to DENV4), that can lead to genetically specific interactions with mosquito populations. Here, we carried out a continent-wide survey of DENV susceptibility using a panel of field-derived Ae. aegypti colonies from across the African range of the species and a colony from Guadeloupe, French West Indies as non-African reference. We found considerable variation in the ability of African Ae. aegypti populations to acquire and replicate a panel of six DENV strains spanning the four DENV types. Although African Ae. aegypti populations were generally less susceptible than the reference non-African population from Guadeloupe, in several instances some African populations were equally or more susceptible than the Guadeloupe population. Moreover, the relative level of susceptibility between African mosquito populations depended on the DENV strain, indicating genetically specific interactions. We conclude that unlike ZIKV susceptibility, there is no clear-cut dichotomy in DENV susceptibility between African and non-African Ae. aegypti. DENV susceptibility of African Ae. aegypti populations is highly heterogeneous and largely governed by the specific pairing of mosquito population and DENV strain.
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Affiliation(s)
- Stéphanie Dabo
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
| | | | - Alicia Lecuyer
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
| | - Davy Jiolle
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Christophe Paupy
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Diego Ayala
- MIVEGEC, Montpellier University, IRD, CNRS, Montpellier, France
- Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
| | - Silvânia da Veiga Leal
- Laboratório de Entomologia Médica, Instituto Nacional de Saúde Pública, Praia, Cabo Verde
| | - Athanase Badolo
- Laboratoire d’Entomologie Fondamentale et Appliquée, Université Joseph Ki-Zerbo, Ouagadougou, Burkina Faso
| | - Anubis Vega-Rúa
- Institut Pasteur of Guadeloupe, Laboratory of Vector Control Research, Transmission Reservoir and Pathogens Diversity Unit, Morne Jolivière, Guadeloupe, France
| | - Massamba Sylla
- Department of Livestock Sciences and Techniques, University Sine Saloum El Hadji Ibrahima NIASS, Kaffrine, Senegal
| | - Jewelna Akorli
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Sampson Otoo
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joel Lutomiah
- Arbovirus/Viral Hemorrhagic Fevers Laboratory, Center for Virus Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Rosemary Sang
- Arbovirus/Viral Hemorrhagic Fevers Laboratory, Center for Virus Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - John-Paul Mutebi
- Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, Paris, France
| | - Noah H. Rose
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
- Current address: Department of Ecology, Behavior, and Evolution, University of California San Diego, La Jolla, California, United States of America
| | - Carolyn S. McBride
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Louis Lambrechts
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, Paris, France
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6
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Merkling SH, Crist AB, Henrion-Lacritick A, Frangeul L, Couderc E, Gausson V, Blanc H, Bergman A, Baidaliuk A, Romoli O, Saleh MC, Lambrechts L. Multifaceted contributions of Dicer2 to arbovirus transmission by Aedes aegypti. Cell Rep 2023; 42:112977. [PMID: 37573505 DOI: 10.1016/j.celrep.2023.112977] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 06/20/2023] [Accepted: 07/28/2023] [Indexed: 08/15/2023] Open
Abstract
Arthropod-borne viruses (arboviruses) transmitted by Aedes aegypti mosquitoes are an increasing threat to global health. The small interfering RNA (siRNA) pathway is considered the main antiviral immune pathway of insects, but its effective impact on arbovirus transmission is surprisingly poorly understood. Here, we use CRISPR-Cas9-mediated gene editing in vivo to mutate Dicer2, a gene encoding the RNA sensor and key component of the siRNA pathway. The loss of Dicer2 enhances early viral replication and systemic viral dissemination of four medically significant arboviruses (chikungunya, Mayaro, dengue, and Zika viruses) representing two viral families. However, Dicer2 mutants and wild-type mosquitoes display overall similar levels of vector competence. In addition, Dicer2 mutants undergo significant virus-induced mortality during infection with chikungunya virus. Together, our results define a multifaceted role for Dicer2 in the transmission of arboviruses by Ae. aegypti mosquitoes and pave the way for further mechanistic investigations.
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Affiliation(s)
- Sarah Hélène Merkling
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France
| | - Anna Beth Crist
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France
| | - Annabelle Henrion-Lacritick
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
| | - Elodie Couderc
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France; Sorbonne Université, Collège Doctoral, 75005 Paris, France
| | - Valérie Gausson
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
| | - Hervé Blanc
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
| | - Alexander Bergman
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France
| | - Artem Baidaliuk
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France; Sorbonne Université, Collège Doctoral, 75005 Paris, France
| | - Ottavia Romoli
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, 75015 Paris, France.
| | - Louis Lambrechts
- Institut Pasteur, Université Paris Cité, CNRS UMR2000, Insect-Virus Interactions Unit, 75015 Paris, France.
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7
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Cereghino C, Roesch F, Carrau L, Hardy A, Ribeiro-Filho HV, Henrion-Lacritick A, Koh C, Marano JM, Bates TA, Rai P, Chuong C, Akter S, Vallet T, Blanc H, Elliott TJ, Brown AM, Michalak P, LeRoith T, Bloom JD, Marques RE, Saleh MC, Vignuzzi M, Weger-Lucarelli J. The E2 glycoprotein holds key residues for Mayaro virus adaptation to the urban Aedes aegypti mosquito. PLoS Pathog 2023; 19:e1010491. [PMID: 37018377 PMCID: PMC10109513 DOI: 10.1371/journal.ppat.1010491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/17/2023] [Accepted: 03/13/2023] [Indexed: 04/06/2023] Open
Abstract
Adaptation to mosquito vectors suited for transmission in urban settings is a major driver in the emergence of arboviruses. To better anticipate future emergence events, it is crucial to assess their potential to adapt to new vector hosts. In this work, we used two different experimental evolution approaches to study the adaptation process of an emerging alphavirus, Mayaro virus (MAYV), to Ae. aegypti, an urban mosquito vector of many other arboviruses. We identified E2-T179N as a key mutation increasing MAYV replication in insect cells and enhancing transmission after escaping the midgut of live Ae. aegypti. In contrast, this mutation decreased viral replication and binding in human fibroblasts, a primary cellular target of MAYV in humans. We also showed that MAYV E2-T179N generates reduced viremia and displays less severe tissue pathology in vivo in a mouse model. We found evidence in mouse fibroblasts that MAYV E2-T179N is less dependent on the Mxra8 receptor for replication than WT MAYV. Similarly, exogenous expression of human apolipoprotein receptor 2 and Mxra8 enhanced WT MAYV replication compared to MAYV E2-T179N. When this mutation was introduced in the closely related chikungunya virus, which has caused major outbreaks globally in the past two decades, we observed increased replication in both human and insect cells, suggesting E2 position 179 is an important determinant of alphavirus host-adaptation, although in a virus-specific manner. Collectively, these results indicate that adaptation at the T179 residue in MAYV E2 may result in increased vector competence-but coming at the cost of optimal replication in humans-and may represent a first step towards a future emergence event.
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Affiliation(s)
- Chelsea Cereghino
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Ferdinand Roesch
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
- UMR 1282 ISP, INRAE Centre Val de Loire, Nouzilly, France
| | - Lucía Carrau
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
- Department of Microbiology, New York University Langone Medical Center, New York, New York, United States of America
| | - Alexandra Hardy
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Helder V. Ribeiro-Filho
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, Brazil
| | - Annabelle Henrion-Lacritick
- Institut Pasteur, Viruses and RNA Interference Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Cassandra Koh
- Institut Pasteur, Viruses and RNA Interference Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Jeffrey M. Marano
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- Translational Biology, Medicine, and Health Graduate Program, Virginia Tech, Roanoke, Virginia, United States of America
| | - Tyler A. Bates
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Pallavi Rai
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Christina Chuong
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Shamima Akter
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- Department of Bioinformatics and Computational Biology, School of Systems Biology, George Mason University, Fairfax, Virginia, United States of America
| | - Thomas Vallet
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Truitt J. Elliott
- Program in Genetics, Bioinformatics, and Computational Biology (GBCB), Virginia Tech, Blacksburg, Virginia, United States of America
- Research and Informatics, University Libraries, Virginia Tech, Blacksburg, Virginia, United States of America
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Anne M. Brown
- Program in Genetics, Bioinformatics, and Computational Biology (GBCB), Virginia Tech, Blacksburg, Virginia, United States of America
| | - Pawel Michalak
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- Edward Via College of Osteopathic Medicine, Monroe, Louisiana, United States of America
- Center for One Health Research, VA-MD Regional College of Veterinary Medicine, Blacksburg, Virginia, Untied States of Ameria
- Institute of Evolution, University of Haifa, Haifa, Israel
| | - Tanya LeRoith
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Jesse D. Bloom
- Basic Sciences Division and Computational Biology Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Rafael Elias Marques
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, Brazil
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
| | - James Weger-Lucarelli
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, Virginia, United States of America
- Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France
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8
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Carrillo-Bustamante P, Koh C, O'Neal AJ, Laukaitis HJ, Levashina EA, Saleh MC, Pedra JHF. Keystone Vector Biology Symposium 2023: emerging concepts and novel technologies. Trends Parasitol 2023; 39:403-409. [PMID: 36973134 DOI: 10.1016/j.pt.2023.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 03/11/2023] [Indexed: 03/29/2023]
Affiliation(s)
| | - Cassandra Koh
- Viruses and RNA Interference Unit, Institut Pasteur, Université Paris Cité, CNRS UMR3569, F-75015 Paris, France.
| | - Anya J O'Neal
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
| | - Hanna J Laukaitis
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
| | - Elena A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany.
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Institut Pasteur, Université Paris Cité, CNRS UMR3569, F-75015 Paris, France.
| | - Joao H F Pedra
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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9
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Koh C, Frangeul L, Blanc H, Ngoagouni C, Boyer S, Dussart P, Grau N, Girod R, Duchemin JB, Saleh MC. Ribosomal RNA (rRNA) sequences from 33 globally distributed mosquito species for improved metagenomics and species identification. eLife 2023; 12:82762. [PMID: 36688360 PMCID: PMC10014081 DOI: 10.7554/elife.82762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
Total RNA sequencing (RNA-seq) is an important tool in the study of mosquitoes and the RNA viruses they vector as it allows assessment of both host and viral RNA in specimens. However, there are two main constraints. First, as with many other species, abundant mosquito ribosomal RNA (rRNA) serves as the predominant template from which sequences are generated, meaning that the desired host and viral templates are sequenced far less. Second, mosquito specimens captured in the field must be correctly identified, in some cases to the sub-species level. Here, we generate mosquito rRNA datasets which will substantially mitigate both of these problems. We describe a strategy to assemble novel rRNA sequences from mosquito specimens and produce an unprecedented dataset of 234 full-length 28S and 18S rRNA sequences of 33 medically important species from countries with known histories of mosquito-borne virus circulation (Cambodia, the Central African Republic, Madagascar, and French Guiana). These sequences will allow both physical and computational removal of rRNA from specimens during RNA-seq protocols. We also assess the utility of rRNA sequences for molecular taxonomy and compare phylogenies constructed using rRNA sequences versus those created using the gold standard for molecular species identification of specimens-the mitochondrial cytochrome c oxidase I (COI) gene. We find that rRNA- and COI-derived phylogenetic trees are incongruent and that 28S and concatenated 28S+18S rRNA phylogenies reflect evolutionary relationships that are more aligned with contemporary mosquito systematics. This significant expansion to the current rRNA reference library for mosquitoes will improve mosquito RNA-seq metagenomics by permitting the optimization of species-specific rRNA depletion protocols for a broader range of species and streamlining species identification by rRNA sequence and phylogenetics.
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Affiliation(s)
- Cassandra Koh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Lionel Frangeul
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Hervé Blanc
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Carine Ngoagouni
- Institut Pasteur de Bangui, Medical Entomology LaboratoryBanguiCentral African Republic
| | - Sébastien Boyer
- Institut Pasteur du Cambodge, Medical and Veterinary Entomology UnitPhnom PenhCambodia
| | | | - Nina Grau
- Institut Pasteur de Madagascar, Medical Entomology UnitAntananarivoMadagascar
| | - Romain Girod
- Institut Pasteur de Madagascar, Medical Entomology UnitAntananarivoMadagascar
| | - Jean-Bernard Duchemin
- Institut Pasteur de la Guyane, Vectopôle Amazonien Emile AbonnencCayenneFrench Guiana
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
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10
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Abstract
The origin of RNA interference (RNAi) is usually explained by a defense-based hypothesis, in which RNAi evolved as a defense against transposable elements (TEs) and RNA viruses and was already present in the last eukaryotic common ancestor (LECA). However, since RNA antisense regulation and double-stranded RNAs (dsRNAs) are ancient and widespread phenomena, the origin of defensive RNAi should have occurred in parallel with its regulative functions to avoid imbalances in gene regulation. Thus, we propose a neutral evolutionary hypothesis for the origin of RNAi in which qualitative system drift from a prokaryotic antisense RNA gene regulation mechanism leads to the formation of RNAi through constructive neutral evolution (CNE). We argue that RNAi was already present in the ancestor of LECA before the need for a new defense system arose and that its presence helped to shape eukaryotic genomic architecture and stability. Where does RNA interference come from? This Essay describes a new step-by-step evolutionary model of how RNA interference might have originated in early eukaryotes through neutral events from the molecular machinery present in prokaryotes.
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Affiliation(s)
- Alessandro Torri
- Virus & RNA interference Unit, Department of Virology, Institut Pasteur, CNRS UMR 3569, Université Paris Cité, Paris, France
- * E-mail: (AT); (M-CS)
| | | | - Thomas Pradeu
- ImmunoConcEpT, CNRS UMR 5164, University of Bordeaux, Bordeaux, France
- Institut d’histoire et de philosophie des sciences et des techniques, CNRS UMR 8590, Pantheon-Sorbonne University, Paris, France
| | - Maria-Carla Saleh
- Virus & RNA interference Unit, Department of Virology, Institut Pasteur, CNRS UMR 3569, Université Paris Cité, Paris, France
- * E-mail: (AT); (M-CS)
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11
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Nigg JC, Mongelli V, Blanc H, Saleh MC. Innovative Toolbox for the Quantification of Drosophila C Virus, Drosophila A Virus, and Nora Virus. J Mol Biol 2021; 434:167308. [PMID: 34678301 DOI: 10.1016/j.jmb.2021.167308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/28/2021] [Accepted: 10/12/2021] [Indexed: 11/29/2022]
Abstract
Quantification of viral replication underlies investigations into host-virus interactions. In Drosophila melanogaster, persistent infections with Drosophila C virus, Drosophila A virus, and Nora virus are commonly observed in nature and in laboratory fly stocks. However, traditional endpoint dilution assays to quantify infectious titers are not compatible with persistently infecting isolates of these viruses that do not cause cytopathic effects in cell culture. Here we present a novel assay based on immunological detection of Drosophila C virus infection that allows quantification of infectious titers for a wider range of Drosophila C virus isolates. We also describe strand specific RT-qPCR assays for quantification of viral negative strand RNA produced during Drosophila C virus, Drosophila A virus, and Nora virus infection. Finally, we demonstrate the utility of these assays for quantification of viral replication during oral infections and persistent infections with each virus.
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Affiliation(s)
- Jared C Nigg
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS UMR 3569, 75724 Paris CEDEX 15, France.
| | - Vanesa Mongelli
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS UMR 3569, 75724 Paris CEDEX 15, France.
| | - Hervé Blanc
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS UMR 3569, 75724 Paris CEDEX 15, France.
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS UMR 3569, 75724 Paris CEDEX 15, France.
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12
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Levi LI, Rezelj VV, Henrion-Lacritick A, Erazo D, Boussier J, Vallet T, Bernhauerová V, Suzuki Y, Carrau L, Weger-Lucarelli J, Saleh MC, Vignuzzi M. Defective viral genomes from chikungunya virus are broad-spectrum antivirals and prevent virus dissemination in mosquitoes. PLoS Pathog 2021; 17:e1009110. [PMID: 33556143 PMCID: PMC7870000 DOI: 10.1371/journal.ppat.1009110] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 10/29/2020] [Indexed: 11/19/2022] Open
Abstract
Defective viral genomes (DVGs) are truncated and/or rearranged viral genomes produced during virus replication. Described in many RNA virus families, some of them have interfering activity on their parental virus and/or strong immunostimulatory potential, and are being considered in antiviral approaches. Chikungunya virus (CHIKV) is an alphavirus transmitted by Aedes spp. that infected millions of humans in the last 15 years. Here, we describe the DVGs arising during CHIKV infection in vitro in mammalian and mosquito cells, and in vivo in experimentally infected Aedes aegypti mosquitoes. We combined experimental and computational approaches to select DVG candidates most likely to have inhibitory activity and showed that, indeed, they strongly interfere with CHIKV replication both in mammalian and mosquito cells. We further demonstrated that some DVGs present broad-spectrum activity, inhibiting several CHIKV strains and other alphaviruses. Finally, we showed that pre-treating Aedes aegypti with DVGs prevented viral dissemination in vivo.
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Affiliation(s)
- Laura I. Levi
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
- École doctorale BioSPC, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Veronica V. Rezelj
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
| | | | - Diana Erazo
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
| | - J Boussier
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
- École doctorale Frontières du vivant, Université Paris Diderot, Paris, France
| | - Thomas Vallet
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
| | - Veronika Bernhauerová
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
- Department of Biophysics and Physical Chemistry, Faculty of Pharmacy, Charles University, Hradec Králové, Czech Republic
| | - Yasutsugu Suzuki
- Institut Pasteur, Viruses and RNAi Unit, CNRS UMR 3569, Paris, France
| | - Lucia Carrau
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
- École doctorale BioSPC, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - James Weger-Lucarelli
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, VA-MD Regional College of Veterinary Medicine, Blacksburg, Virginia, United States of America
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNAi Unit, CNRS UMR 3569, Paris, France
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis Unit, CNRS UMR 3569, Paris, France
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13
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Abstract
As an overarching immune mechanism, RNA interference (RNAi) displays pathogen specificity and memory via different pathways. The small interfering RNA (siRNA) pathway is the primary antiviral defense mechanism against RNA viruses of insects and plays a lesser role in defense against DNA viruses. Reflecting the pivotal role of the siRNA pathway in virus selection, different virus families have independently evolved unique strategies to counter this host response, including protein-mediated, decoy RNA-based, and microRNA-based strategies. In this review, we outline the interplay between insect viruses and the different pathways of the RNAi antiviral response; describe practical application of these interactions for improved expression systems and for pest and disease management; and highlight research avenues for advancement of the field.
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Affiliation(s)
- Bryony C Bonning
- Department of Entomology and Nematology, University of Florida, Gainesville, Florida 32611, USA;
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Institut Pasteur, CNRS UMR 3569, 75724 Paris CEDEX 15, France;
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14
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Suzuki Y, Baidaliuk A, Miesen P, Frangeul L, Crist AB, Merkling SH, Fontaine A, Lequime S, Moltini-Conclois I, Blanc H, van Rij RP, Lambrechts L, Saleh MC. Non-retroviral Endogenous Viral Element Limits Cognate Virus Replication in Aedes aegypti Ovaries. Curr Biol 2020; 30:3495-3506.e6. [PMID: 32679098 PMCID: PMC7522710 DOI: 10.1016/j.cub.2020.06.057] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/06/2020] [Accepted: 06/16/2020] [Indexed: 12/27/2022]
Abstract
Endogenous viral elements (EVEs) are viral sequences integrated in host genomes. A large number of non-retroviral EVEs was recently detected in Aedes mosquito genomes, leading to the hypothesis that mosquito EVEs may control exogenous infections by closely related viruses. Here, we experimentally investigated the role of an EVE naturally found in Aedes aegypti populations and derived from the widespread insect-specific virus, cell-fusing agent virus (CFAV). Using CRISPR-Cas9 genome editing, we created an Ae. aegypti line lacking the CFAV EVE. Absence of the EVE resulted in increased CFAV replication in ovaries, possibly modulating vertical transmission of the virus. Viral replication was controlled by targeting of viral RNA by EVE-derived P-element-induced wimpy testis-interacting RNAs (piRNAs). Our results provide evidence that antiviral piRNAs are produced in the presence of a naturally occurring EVE and its cognate virus, demonstrating a functional link between non-retroviral EVEs and antiviral immunity in a natural insect-virus interaction. Aedes aegypti harbors EVEs with high sequence identity to a contemporary RNA virus EVE-derived piRNAs target genomic viral RNA in infected mosquitoes Ablation of EVE results in increased viral replication in Aedes aegypti ovaries piRNA pathway fulfills antiviral function in presence of EVE and cognate virus
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Affiliation(s)
- Yasutsugu Suzuki
- Viruses and RNA Interference Unit, Institut Pasteur, UMR3569, CNRS, Paris, France
| | - Artem Baidaliuk
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRS, Paris, France; Collège Doctoral, Sorbonne Université, 75005 Paris, France
| | - Pascal Miesen
- Viruses and RNA Interference Unit, Institut Pasteur, UMR3569, CNRS, Paris, France; Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Lionel Frangeul
- Viruses and RNA Interference Unit, Institut Pasteur, UMR3569, CNRS, Paris, France
| | - Anna B Crist
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRS, Paris, France
| | - Sarah H Merkling
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRS, Paris, France
| | - Albin Fontaine
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRS, Paris, France
| | - Sebastian Lequime
- Laboratory of Clinical and Epidemiological Virology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | | | - Hervé Blanc
- Viruses and RNA Interference Unit, Institut Pasteur, UMR3569, CNRS, Paris, France
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Louis Lambrechts
- Insect-Virus Interactions Unit, Institut Pasteur, UMR2000, CNRS, Paris, France.
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Institut Pasteur, UMR3569, CNRS, Paris, France.
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15
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Torri A, Mongelli V, Mondotte JA, Saleh MC. Viral Infection and Stress Affect Protein Levels of Dicer 2 and Argonaute 2 in Drosophila melanogaster. Front Immunol 2020; 11:362. [PMID: 32194567 PMCID: PMC7065269 DOI: 10.3389/fimmu.2020.00362] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/14/2020] [Indexed: 12/21/2022] Open
Abstract
The small interfering RNA (siRNA) pathway of Drosophila melanogaster, mainly characterized by the activity of the enzymes Dicer 2 (Dcr-2) and Argonaute 2 (Ago-2), has been described as the major antiviral immune response. Several lines of evidence demonstrated its pivotal role in conferring resistance against viral infections at cellular and systemic level. However, only few studies have addressed the regulation and induction of this system upon infection and knowledge on stability and turnover of the siRNA pathway core components transcripts and proteins remains scarce. In the current work, we explore whether the siRNA pathway is regulated following viral infection in D. melanogaster. After infecting different fly strains with two different viruses and modes of infection, we observed changes in Dcr-2 and Ago-2 protein concentrations that were not related with changes in gene expression. This response was observed either upon viral infection or upon stress-related experimental procedure, indicating a bivalent function of the siRNA system operating as a general gene regulation rather than a specific antiviral system.
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Affiliation(s)
- Alessandro Torri
- Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche, Institut Pasteur, Paris, France
| | - Vanesa Mongelli
- Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche, Institut Pasteur, Paris, France
| | - Juan A Mondotte
- Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche, Institut Pasteur, Paris, France
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche, Institut Pasteur, Paris, France
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16
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Merkling SH, Raquin V, Dabo S, Henrion-Lacritick A, Blanc H, Moltini-Conclois I, Frangeul L, Varet H, Saleh MC, Lambrechts L. Tudor-SN Promotes Early Replication of Dengue Virus in the Aedes aegypti Midgut. iScience 2020; 23:100870. [PMID: 32059176 PMCID: PMC7054812 DOI: 10.1016/j.isci.2020.100870] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/24/2019] [Accepted: 01/24/2020] [Indexed: 01/15/2023] Open
Abstract
Diseases caused by mosquito-borne viruses have been on the rise for the last decades, and novel methods aiming to use laboratory-engineered mosquitoes that are incapable of carrying viruses have been developed to reduce pathogen transmission. This has stimulated efforts to identify optimal target genes that are naturally involved in mosquito antiviral defenses or required for viral replication. Here, we investigated the role of a member of the Tudor protein family, Tudor-SN, upon dengue virus infection in the mosquito Aedes aegypti. Tudor-SN knockdown reduced dengue virus replication in the midgut of Ae. aegypti females. In immunofluorescence assays, Tudor-SN localized to the nucleolus in both Ae. aegypti and Aedes albopictus cells. A reporter assay and small RNA profiling demonstrated that Tudor-SN was not required for RNA interference function in vivo. Collectively, these results defined a novel proviral role for Tudor-SN upon early dengue virus infection of the Ae. aegypti midgut.
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Affiliation(s)
- Sarah Hélène Merkling
- Institut Pasteur, Insect-Virus Interactions Unit, UMR2000, CNRS, 75015 Paris, France
| | - Vincent Raquin
- Institut Pasteur, Insect-Virus Interactions Unit, UMR2000, CNRS, 75015 Paris, France
| | - Stéphanie Dabo
- Institut Pasteur, Insect-Virus Interactions Unit, UMR2000, CNRS, 75015 Paris, France
| | | | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference Unit, UMR3569, CNRS, 75015 Paris, France
| | | | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA Interference Unit, UMR3569, CNRS, 75015 Paris, France
| | - Hugo Varet
- Hub de Bioinformatique et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, USR 3756, CNRS, Paris, France; Plate-forme Technologique Biomics - Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, UMR3569, CNRS, 75015 Paris, France.
| | - Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions Unit, UMR2000, CNRS, 75015 Paris, France.
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17
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Abstract
The inexorable emergence of mosquito-borne arboviruses and the failure of traditional vector control methods to prevent their transmission have triggered the development of alternative entomological interventions to render mosquito populations incapable of carrying arboviruses. Here, we use a theoretical framework to argue that decreasing mosquito tolerance to arbovirus infection could be a more evolutionarily sustainable disease control strategy than increasing mosquito resistance. Increasing resistance is predicted to select for mutant arboviruses escaping resistance, whereas reducing tolerance should lead to the death of infected vectors and thus select for mosquito-attenuated arbovirus variants that are less transmissible.
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Affiliation(s)
- Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions Unit, Department of Virology, UMR2000, CNRS, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, UMR3569, CNRS, 75015 Paris, France.
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18
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19
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Mondotte JA, Gausson V, Frangeul L, Blanc H, Lambrechts L, Saleh MC. Immune priming and clearance of orally acquired RNA viruses in Drosophila. Nat Microbiol 2018; 3:1394-1403. [PMID: 30374170 DOI: 10.1038/s41564-018-0265-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/06/2018] [Indexed: 12/17/2022]
Abstract
Immune responses in insects are differentially triggered depending on the infection route used by the pathogen. In most studies involving Drosophila melanogaster and viruses, infection is done by injection, while oral infection, which is probably the most common route of viral entry in nature, remains unexplored. Here, we orally infected adults and larvae from wild-type and RNA interference (RNAi) mutant flies with different RNA viruses. We found that, in contrast with what is observed following virus injection, oral infections initiated at larval or adult stages are cleared in adult flies. Virus elimination occurred despite a larger infectious dose than for injected flies and evidence of viral replication. RNAi mutant flies suffered greater mortality relative to wild-type flies following oral infection, but they also eliminated the virus, implying that RNAi is not essential for viral clearance and that other immune mechanisms act during oral infections. We further showed that information of infection by RNA viruses acquired orally leaves a trace under a DNA form, which confers protection against future reinfection by the same virus. Together, this work presents evidence of clearance and immune priming for RNA viruses in insects and challenges the current view of antiviral immunity in insects.
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Affiliation(s)
- Juan A Mondotte
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, CNRS Unité Mixte de Recherche 3569, Paris, France
| | - Valérie Gausson
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, CNRS Unité Mixte de Recherche 3569, Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, CNRS Unité Mixte de Recherche 3569, Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, CNRS Unité Mixte de Recherche 3569, Paris, France
| | - Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions Group, Department of Genomes and Genetics, CNRS Unité Mixte de Recherche 2000, Paris, France
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, Department of Virology, CNRS Unité Mixte de Recherche 3569, Paris, France.
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20
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Poirier EZ, Goic B, Tomé-Poderti L, Frangeul L, Boussier J, Gausson V, Blanc H, Vallet T, Loyd H, Levi LI, Lanciano S, Baron C, Merkling SH, Lambrechts L, Mirouze M, Carpenter S, Vignuzzi M, Saleh MC. Dicer-2-Dependent Generation of Viral DNA from Defective Genomes of RNA Viruses Modulates Antiviral Immunity in Insects. Cell Host Microbe 2018; 23:353-365.e8. [PMID: 29503180 PMCID: PMC5857290 DOI: 10.1016/j.chom.2018.02.001] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/08/2017] [Accepted: 02/07/2018] [Indexed: 12/21/2022]
Abstract
The RNAi pathway confers antiviral immunity in insects. Virus-specific siRNA responses are amplified via the reverse transcription of viral RNA to viral DNA (vDNA). The nature, biogenesis, and regulation of vDNA are unclear. We find that vDNA produced during RNA virus infection of Drosophila and mosquitoes is present in both linear and circular forms. Circular vDNA (cvDNA) is sufficient to produce siRNAs that confer partially protective immunity when challenged with a cognate virus. cvDNAs bear homology to defective viral genomes (DVGs), and DVGs serve as templates for vDNA and cvDNA synthesis. Accordingly, DVGs promote the amplification of vDNA-mediated antiviral RNAi responses in infected Drosophila. Furthermore, vDNA synthesis is regulated by the DExD/H helicase domain of Dicer-2 in a mechanism distinct from its role in siRNA generation. We suggest that, analogous to mammalian RIG-I-like receptors, Dicer-2 functions like a pattern recognition receptor for DVGs to modulate antiviral immunity in insects.
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Affiliation(s)
- Enzo Z Poirier
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; University of Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 75013 Paris, France
| | - Bertsy Goic
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lorena Tomé-Poderti
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Jérémy Boussier
- Institut Pasteur, Immunobiology of Dendritic Cells, Institut National de la Santé et de la Recherche Médicale, U1223, 75015 Paris, France
| | - Valérie Gausson
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Thomas Vallet
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hyelee Loyd
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Laura I Levi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sophie Lanciano
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Chloé Baron
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sarah H Merkling
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Marie Mirouze
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Susan Carpenter
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
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Abstract
The use of Drosophila as a model organism has made an important contribution to our understanding of the function and regulation of innate immunity in insects. Indeed, insects can discriminate between different types of pathogens and mount specific and effective responses. Strikingly, the same pathogen can trigger a different immune response in the same organism, depending solely on the route of infection by which the pathogen is delivered. In this review, we recapitulate what is known about antiviral responses in Drosophila, and how they are triggered depending on the route and the mode used for the virus to infect its host.
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Affiliation(s)
- Juan A Mondotte
- Institut Pasteur, Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche 3569, Paris, France
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference Unit, CNRS Unité Mixte de Recherche 3569, Paris, France.
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22
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Abstract
Like every other organism on Earth, insects are infected with viruses, and they rely on RNA interference (RNAi) mechanisms to circumvent viral infections. A remarkable characteristic of RNAi is that it is both broadly acting, because it is triggered by double-stranded RNA molecules derived from virtually any virus, and extremely specific, because it targets only the particular viral sequence that initiated the process. Reviews covering the different facets of the RNAi antiviral immune response in insects have been published elsewhere. In this review, we build a framework to guide future investigation. We focus on the remaining questions and avenues of research that need to be addressed to move the field forward, including issues such as the activity of viral suppressors of RNAi, comparative genomics, the development of detailed maps of the subcellular localization of viral replication complexes with the RNAi machinery, and the regulation of the antiviral RNAi response.
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Affiliation(s)
- Vanesa Mongelli
- Viruses and RNA Interference Unit, Department of Virology, CNRS UMR 3569, Institut Pasteur, 75724 Paris Cedex 15, France;
| | - Maria-Carla Saleh
- Viruses and RNA Interference Unit, Department of Virology, CNRS UMR 3569, Institut Pasteur, 75724 Paris Cedex 15, France;
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23
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Girardi E, Miesen P, Pennings B, Frangeul L, Saleh MC, van Rij RP. Histone-derived piRNA biogenesis depends on the ping-pong partners Piwi5 and Ago3 in Aedes aegypti. Nucleic Acids Res 2017; 45:4881-4892. [PMID: 28115625 PMCID: PMC5416884 DOI: 10.1093/nar/gkw1368] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 01/04/2017] [Indexed: 12/13/2022] Open
Abstract
The piRNA pathway is of key importance in controlling transposable elements in most animal species. In the vector mosquito Aedes aegypti, the presence of eight PIWI proteins and the accumulation of viral piRNAs upon arbovirus infection suggest additional functions of the piRNA pathway beyond genome defense. To better understand the regulatory potential of this pathway, we analyzed in detail host-derived piRNAs in A. aegypti Aag2 cells. We show that a large repertoire of protein-coding genes and non-retroviral integrated RNA virus elements are processed into genic piRNAs by different combinations of PIWI proteins. Among these, we identify a class of genes that produces piRNAs from coding sequences in an Ago3- and Piwi5-dependent fashion. We demonstrate that the replication-dependent histone gene family is a genic source of ping-pong dependent piRNAs and that histone-derived piRNAs are dynamically expressed throughout the cell cycle, suggesting a role for the piRNA pathway in the regulation of histone gene expression. Moreover, our results establish the Aag2 cell line as an accessible experimental model to study gene-derived piRNAs.
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Affiliation(s)
- Erika Girardi
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Bas Pennings
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA interference, CNRS URM 3569, 75724 Paris Cedex 15, France
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA interference, CNRS URM 3569, 75724 Paris Cedex 15, France
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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24
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Passoni G, Langevin C, Palha N, Mounce BC, Briolat V, Affaticati P, De Job E, Joly JS, Vignuzzi M, Saleh MC, Herbomel P, Boudinot P, Levraud JP. Imaging of viral neuroinvasion in the zebrafish reveals that Sindbis and chikungunya viruses favour different entry routes. Dis Model Mech 2017; 10:847-857. [PMID: 28483796 PMCID: PMC5536907 DOI: 10.1242/dmm.029231] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/02/2017] [Indexed: 12/13/2022] Open
Abstract
Alphaviruses, such as chikungunya virus (CHIKV) and Sindbis virus (SINV), are vector-borne pathogens that cause acute illnesses in humans and are sometimes associated with neuropathies, especially in infants and elderly patients. Little is known about their mechanism of entry into the central nervous system (CNS), even for SINV, which has been used extensively as a model for viral encephalopathies. We previously established a CHIKV infection model in the optically transparent zebrafish larva; here we describe a new SINV infection model in this host. We imaged in vivo the onset and progression of the infection caused by intravenous SINV inoculation. Similar to that described for CHIKV, infection in the periphery was detected early and was transient, whereas CNS infection started at later time points and was persistent or progressive. We then tested the possible mechanisms of neuroinvasion by CHIKV and SINV. Neither virus relied on macrophage-mediated transport to access the CNS. CHIKV, but not SINV, always infects endothelial cells of the brain vasculature. By contrast, axonal transport was much more efficient with SINV than CHIKV, both from the periphery to the CNS and between neural tissues. Thus, the preferred mechanisms of neuroinvasion by these two related viruses are distinct, providing a powerful imaging-friendly system to compare mechanisms and prevention methods of encephalopathies.
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Affiliation(s)
- Gabriella Passoni
- Virology and Molecular Immunology, INRA, Université Paris-Saclay, Domaine de Vilvert, Jouy-en-Josas F-78352, France.,Macrophages and Development of Immunity, Institut Pasteur, CNRS UMR 3738, 25 rue du docteur Roux, Paris F-75015, France
| | - Christelle Langevin
- Virology and Molecular Immunology, INRA, Université Paris-Saclay, Domaine de Vilvert, Jouy-en-Josas F-78352, France
| | - Nuno Palha
- Macrophages and Development of Immunity, Institut Pasteur, CNRS UMR 3738, 25 rue du docteur Roux, Paris F-75015, France
| | - Bryan C Mounce
- Viral Populations and Pathogenesis Unit, Institut Pasteur, CNRS UMR 3569, Paris F-75015, France
| | - Valérie Briolat
- Macrophages and Development of Immunity, Institut Pasteur, CNRS UMR 3738, 25 rue du docteur Roux, Paris F-75015, France
| | - Pierre Affaticati
- Tefor Core Facility, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, Gif-sur-Yvette F-91190, France
| | - Elodie De Job
- Tefor Core Facility, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, Gif-sur-Yvette F-91190, France
| | - Jean-Stéphane Joly
- Tefor Core Facility, Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, Gif-sur-Yvette F-91190, France
| | - Marco Vignuzzi
- Viral Populations and Pathogenesis Unit, Institut Pasteur, CNRS UMR 3569, Paris F-75015, France
| | - Maria-Carla Saleh
- Viruses and RNA Interference, Institut Pasteur, CNRS UMR 3569, Paris F-75015, France
| | - Philippe Herbomel
- Macrophages and Development of Immunity, Institut Pasteur, CNRS UMR 3738, 25 rue du docteur Roux, Paris F-75015, France
| | - Pierre Boudinot
- Virology and Molecular Immunology, INRA, Université Paris-Saclay, Domaine de Vilvert, Jouy-en-Josas F-78352, France
| | - Jean-Pierre Levraud
- Macrophages and Development of Immunity, Institut Pasteur, CNRS UMR 3738, 25 rue du docteur Roux, Paris F-75015, France
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25
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Tomé-Poderti L, Saleh MC. R.I.P. dead bacteria, you will not be attacked. Nat Immunol 2016; 17:1138-40. [DOI: 10.1038/ni.3562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Saleh MC. Editorial overview: Host-microbe interactions: viruses: Viral sensing and activation of immunity. Curr Opin Microbiol 2014; 20:x-xi. [PMID: 25066799 PMCID: PMC7128443 DOI: 10.1016/j.mib.2014.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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27
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van Mierlo JT, Overheul GJ, Obadia B, van Cleef KWR, Webster CL, Saleh MC, Obbard DJ, van Rij RP. Novel Drosophila viruses encode host-specific suppressors of RNAi. PLoS Pathog 2014; 10:e1004256. [PMID: 25032815 PMCID: PMC4102588 DOI: 10.1371/journal.ppat.1004256] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 06/03/2014] [Indexed: 12/24/2022] Open
Abstract
The ongoing conflict between viruses and their hosts can drive the co-evolution between host immune genes and viral suppressors of immunity. It has been suggested that an evolutionary ‘arms race’ may occur between rapidly evolving components of the antiviral RNAi pathway of Drosophila and viral genes that antagonize it. We have recently shown that viral protein 1 (VP1) of Drosophila melanogaster Nora virus (DmelNV) suppresses Argonaute-2 (AGO2)-mediated target RNA cleavage (slicer activity) to antagonize antiviral RNAi. Here we show that viral AGO2 antagonists of divergent Nora-like viruses can have host specific activities. We have identified novel Nora-like viruses in wild-caught populations of D. immigrans (DimmNV) and D. subobscura (DsubNV) that are 36% and 26% divergent from DmelNV at the amino acid level. We show that DimmNV and DsubNV VP1 are unable to suppress RNAi in D. melanogaster S2 cells, whereas DmelNV VP1 potently suppresses RNAi in this host species. Moreover, we show that the RNAi suppressor activity of DimmNV VP1 is restricted to its natural host species, D. immigrans. Specifically, we find that DimmNV VP1 interacts with D. immigrans AGO2, but not with D. melanogaster AGO2, and that it suppresses slicer activity in embryo lysates from D. immigrans, but not in lysates from D. melanogaster. This species-specific interaction is reflected in the ability of DimmNV VP1 to enhance RNA production by a recombinant Sindbis virus in a host-specific manner. Our results emphasize the importance of analyzing viral RNAi suppressor activity in the relevant host species. We suggest that rapid co-evolution between RNA viruses and their hosts may result in host species-specific activities of RNAi suppressor proteins, and therefore that viral RNAi suppressors could be host-specificity factors. Viruses and their hosts can engage in an evolutionary arms race. Viruses may select for hosts with more effective immune responses, whereas the immune response of the host may select for viruses that evade the immune system. These viral counter-defenses may in turn drive adaptations in host immune genes. A potential outcome of this perpetual cycle is that the interaction between virus and host becomes more specific. In insects, the host antiviral RNAi machinery exerts strong evolutionary pressure that has led to the evolution of viral proteins that can antagonize the RNAi response. We have identified novel viruses that infect different fruit fly species and we show that the RNAi suppressor proteins of these viruses can be specific to their host. Furthermore, we show that these proteins can enhance virus replication in a host-specific manner. These results are in line with the hypothesis that virus-host co-evolution shapes the genomes of both virus and host. Moreover, our results suggest that RNAi suppressor proteins have the potential to determine host specificity of viruses.
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Affiliation(s)
- Joël T. van Mierlo
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Gijs J. Overheul
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Benjamin Obadia
- Institut Pasteur, Viruses and RNA interference Unit and Centre National de la Recherche Scientifique, UMR 3569, Paris, France
| | - Koen W. R. van Cleef
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Claire L. Webster
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA interference Unit and Centre National de la Recherche Scientifique, UMR 3569, Paris, France
| | - Darren J. Obbard
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (DJO); (RPvR)
| | - Ronald P. van Rij
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
- * E-mail: (DJO); (RPvR)
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28
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Moyano AJ, Tobares RA, Rizzi YS, Krapp AR, Mondotte JA, Bocco JL, Saleh MC, Carrillo N, Smania AM. A long-chain flavodoxin protects Pseudomonas aeruginosa from oxidative stress and host bacterial clearance. PLoS Genet 2014; 10:e1004163. [PMID: 24550745 PMCID: PMC3923664 DOI: 10.1371/journal.pgen.1004163] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/20/2013] [Indexed: 12/12/2022] Open
Abstract
Long-chain flavodoxins, ubiquitous electron shuttles containing flavin mononucleotide (FMN) as prosthetic group, play an important protective role against reactive oxygen species (ROS) in various microorganisms. Pseudomonas aeruginosa is an opportunistic pathogen which frequently has to face ROS toxicity in the environment as well as within the host. We identified a single ORF, hereafter referred to as fldP (for flavodoxin from P. aeruginosa), displaying the highest similarity in length, sequence identity and predicted secondary structure with typical long-chain flavodoxins. The gene was cloned and expressed in Escherichia coli. The recombinant product (FldP) could bind FMN and exhibited flavodoxin activity in vitro. Expression of fldP in P. aeruginosa was induced by oxidative stress conditions through an OxyR-independent mechanism, and an fldP-null mutant accumulated higher intracellular ROS levels and exhibited decreased tolerance to H2O2 toxicity compared to wild-type siblings. The mutant phenotype could be complemented by expression of a cyanobacterial flavodoxin. Overexpression of FldP in a mutT-deficient P. aeruginosa strain decreased H2O2-induced cell death and the hypermutability caused by DNA oxidative damage. FldP contributed to the survival of P. aeruginosa within cultured mammalian macrophages and in infected Drosophila melanogaster, which led in turn to accelerated death of the flies. Interestingly, the fldP gene is present in some but not all P. aeruginosa strains, constituting a component of the P. aeruginosa accessory genome. It is located in a genomic island as part of a self-regulated polycistronic operon containing a suite of stress-associated genes. The collected results indicate that the fldP gene encodes a long-chain flavodoxin, which protects the cell from oxidative stress, thereby expanding the capabilities of P. aeruginosa to thrive in hostile environments. Coping with toxic reactive oxygen species (ROS) generated as by-products of aerobic metabolism is a major challenge for O2-thriving organisms, which deploy multilevel responses to prevent ROS-triggered damage, including membrane modifications, induction of antioxidant and repair systems and/or replacement of ROS-sensitive targets by resistant isofunctional versions, among others. The opportunistic pathogen Pseudomonas aeruginosa is frequently exposed to ROS in the environment as well as within the host, and we describe herein a new response by which this microorganism can deal with oxidative stress. This pathway depends on a previously uncharacterized gene that we named fldP (for flavodoxin from P. aeruginosa), which encodes a flavoprotein that belongs to the family of long-chain flavodoxins. FldP exhibited a protective role against ROS-dependent physiological and mutational damage, and contributed to the survival of P. aeruginosa during in vivo infection of flies as well as within mammalian macrophagic cells. Thus, fldP increases the adaptive repertoire of P. aeruginosa to face oxidative stress.
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Affiliation(s)
- Alejandro J. Moyano
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Romina A. Tobares
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Yanina S. Rizzi
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Adriana R. Krapp
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Juan A. Mondotte
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR3569, Paris, France
| | - José L. Bocco
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR3569, Paris, France
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Andrea M. Smania
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
- * E-mail:
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29
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Rozen-Gagnon K, Stapleford KA, Mongelli V, Blanc H, Failloux AB, Saleh MC, Vignuzzi M. Alphavirus mutator variants present host-specific defects and attenuation in mammalian and insect models. PLoS Pathog 2014; 10:e1003877. [PMID: 24453971 PMCID: PMC3894214 DOI: 10.1371/journal.ppat.1003877] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/25/2013] [Indexed: 01/26/2023] Open
Abstract
Arboviruses cycle through both vertebrates and invertebrates, which requires them to adapt to disparate hosts while maintaining genetic integrity during genome replication. To study the genetic mechanisms and determinants of these processes, we use chikungunya virus (CHIKV), a re-emerging human pathogen transmitted by the Aedes mosquito. We previously isolated a high fidelity (or antimutator) polymerase variant, C483Y, which had decreased fitness in both mammalian and mosquito hosts, suggesting this residue may be a key molecular determinant. To further investigate effects of position 483 on RNA-dependent RNA-polymerase (RdRp) fidelity, we substituted every amino acid at this position. We isolated novel mutators with decreased replication fidelity and higher mutation frequencies, allowing us to examine the fitness of error-prone arbovirus variants. Although CHIKV mutators displayed no major replication defects in mammalian cell culture, they had reduced specific infectivity and were attenuated in vivo. Unexpectedly, mutator phenotypes were suppressed in mosquito cells and the variants exhibited significant defects in RNA synthesis. Consequently, these replication defects resulted in strong selection for reversion during infection of mosquitoes. Since residue 483 is conserved among alphaviruses, we examined the analogous mutations in Sindbis virus (SINV), which also reduced polymerase fidelity and generated replication defects in mosquito cells. However, replication defects were mosquito cell-specific and were not observed in Drosophila S2 cells, allowing us to evaluate the potential attenuation of mutators in insect models where pressure for reversion was absent. Indeed, the SINV mutator variant was attenuated in fruit flies. These findings confirm that residue 483 is a determinant regulating alphavirus polymerase fidelity and demonstrate proof of principle that arboviruses can be attenuated in mammalian and insect hosts by reducing fidelity. Chikungunya (CHIKV) is a re-emerging mosquito-borne virus that constitutes a major and growing human health burden. Like all RNA viruses, during viral replication CHIKV copies its genome using a polymerase that makes an average of one mistake per replication cycle. Therefore, a single virus generates millions of viral progeny that carry a multitude of distinct mutations in their genomes. In this study, we isolated CHIKV mutators (strains that make more errors than the wildtype virus), to study how higher mutation rates affect fitness in arthropod-borne viruses (arboviruses). CHIKV mutators have reduced virulence in mice and severe replication defects in Aedes mosquito cells. However, these replication defects result in selective pressure for reversion of mutators to a wildtype polymerase in mosquito hosts. To examine how mutators would behave in an insect model in absence of this genetic instability, we isolated mutators of a related virus, Sindbis virus (SINV). SINV mutators had no replication defect in fruit fly (Drosophila) cells, and a SINV mutator strain was stable and attenuated in fruit flies. This work shows proof of principle that arbovirus mutators can exhibit attenuation in both mammalian and insect hosts, and may remain a viable vaccine strategy.
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Affiliation(s)
- Kathryn Rozen-Gagnon
- Institut Pasteur, Viral Populations and Pathogenesis, CNRS UMR 3569, Paris, France
- University Paris Diderot, Sorbonne Paris Cite, Cellule Pasteur, Paris, France
| | | | - Vanesa Mongelli
- Institut Pasteur, Viruses and RNA Interference, UMR 3569, Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viral Populations and Pathogenesis, CNRS UMR 3569, Paris, France
| | | | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, UMR 3569, Paris, France
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis, CNRS UMR 3569, Paris, France
- * E-mail:
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30
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Karlikow M, Goic B, Saleh MC. RNAi and antiviral defense in Drosophila: setting up a systemic immune response. Dev Comp Immunol 2014; 42:85-92. [PMID: 23684730 DOI: 10.1016/j.dci.2013.05.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 06/02/2023]
Abstract
RNA interference (RNAi) controls gene expression in eukaryotic cells and thus, cellular homeostasis. In addition, in plants, nematodes and arthropods it is a central antiviral effector mechanism. Antiviral RNAi has been well described as a cell autonomous response, which is triggered by double-stranded RNA (dsRNA) molecules. This dsRNA is the precursor for the silencing of viral RNA in a sequence-specific manner. In plants, systemic antiviral immunity has been demonstrated, however much less is known in animals. Recently, some evidence for a systemic antiviral response in arthropods has come to light. Cell autonomous RNAi may not be sufficient to reach an efficient antiviral response, and the organism might rely on the spread and uptake of an RNAi signal of unknown origin. In this review, we offer a perspective on how RNAi-mediated antiviral immunity could confer systemic protection in insects and we propose directions for future research to understand the mechanism of RNAi-immune signal sorting, spreading and amplification.
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Affiliation(s)
- Margot Karlikow
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR3569, Paris, France
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31
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Saleh MC, McConkey S. NADH-dependent cytochrome b5 reductase and NADPH methemoglobin reductase activity in the erythrocytes of Oncorhynchus mykiss. Fish Physiol Biochem 2012; 38:1807-1813. [PMID: 22733093 DOI: 10.1007/s10695-012-9677-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 06/11/2012] [Indexed: 06/01/2023]
Abstract
Methemoglobin is oxidized hemoglobin that cannot bind to or dissociate from oxygen. In fish, it is most commonly caused by exposure to excess nitrites and can lead to abnormal swimming, buoyancy, or death. The methemoglobin concentration in mammals is determined by the balance of oxidizing agents versus reducing enzymes in erythrocytes. The objective of our studies was to characterize the enzymes that reduce methemoglobin in fish erythrocytes. Whole blood was collected from healthy rainbow trout. Methemoglobin was induced in vitro by NaNO(2) exposure. Methemoglobin reduction in controls was compared to reduction in samples with added NADH, NADPH, or NADPH and methylene blue. Rainbow trout whole blood was also fractionated into cytosol, microsomal, and mitochondria/plasma membranes/nuclei fractions. The fractions were compared for NADH-dependent cytochrome b5 reductase (CB5R) activity and for nitrite induction of methemoglobin. The CB5R activity in rainbow trout erythrocytes was compared to the CB5R activity in equine, feline, and canine erythrocytes. Rainbow trout erythrocytes had significant NADPH methemoglobin reductase activity in the presence of methylene blue (P < 0.001). The CB5R activity was greatest (P < 0.001) in the plasma membrane/mitochondria/nuclei fraction. The CB5R activity in rainbow trout erythrocytes was not significantly different than canine or equine activity but was significantly lower than feline CB5R activity (P < 0.0001). Methemoglobin in rainbow trout erythrocytes can be reduced by CB5R or NADPH-dependent methemoglobin reductase. Unlike mammalian anuclear erythrocytes, which are dependent on soluble CB5R, the nucleated RBCs of rainbow trout use membrane-bound CB5R to reduce methemoglobin.
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Affiliation(s)
- M C Saleh
- Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada
| | - S McConkey
- Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada.
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32
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Vodovar N, Bronkhorst AW, van Cleef KWR, Miesen P, Blanc H, van Rij RP, Saleh MC. Arbovirus-derived piRNAs exhibit a ping-pong signature in mosquito cells. PLoS One 2012; 7:e30861. [PMID: 22292064 PMCID: PMC3265520 DOI: 10.1371/journal.pone.0030861] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/22/2011] [Indexed: 12/26/2022] Open
Abstract
The siRNA pathway is an essential antiviral mechanism in insects. Whether other RNA interference pathways are involved in antiviral defense remains unclear. Here, we report in cells derived from the two main vectors for arboviruses, Aedes albopictus and Aedes aegypti, the production of viral small RNAs that exhibit the hallmarks of ping-pong derived piwi-associated RNAs (piRNAs) after infection with positive or negative sense RNA viruses. Furthermore, these cells produce endogenous piRNAs that mapped to transposable elements. Our results show that these mosquito cells can initiate de novo piRNA production and recapitulate the ping-pong dependent piRNA pathway upon viral infection. The mechanism of viral-piRNA production is discussed.
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Affiliation(s)
- Nicolas Vodovar
- Institut Pasteur, Viruses and RNA interference Group and Centre National de la Recherche Scientifique URA 3015, Paris, France
| | - Alfred W. Bronkhorst
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Koen W. R. van Cleef
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Pascal Miesen
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA interference Group and Centre National de la Recherche Scientifique URA 3015, Paris, France
| | - Ronald P. van Rij
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands
- * E-mail: (RPvR); (M-CS)
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA interference Group and Centre National de la Recherche Scientifique URA 3015, Paris, France
- * E-mail: (RPvR); (M-CS)
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Saleh MC, Connell BJ, Saleh TM. Resveratrol preconditioning induces cellular stress proteins and is mediated via NMDA and estrogen receptors. Neuroscience 2009; 166:445-54. [PMID: 20040366 DOI: 10.1016/j.neuroscience.2009.12.060] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/22/2009] [Accepted: 12/23/2009] [Indexed: 11/20/2022]
Abstract
Resveratrol pretreatment has been shown to provide neuroprotection in models of cerebral ischemia. This phenomenon, commonly termed preconditioning, promotes ischemic tolerance and may involve mild activation of endoplasmic reticulum stress pathways in the affected tissue. Systemic injection of resveratrol (2 x 10(-3), 2 x 10(-4), 1 x 10(-4) mg/kg) 30 min prior to a 4 h period of right middle cerebral artery occlusion significantly reduced infarct area in the insular region of rat prefrontal cortex. This affect was blocked when resveratrol treatment was combined with a non-selective estrogen receptor antagonist, or preceded by intracortical injection of an NMDA receptor antagonist. The neuroprotective effect of resveratrol was associated with reduced renal sympathetic nerve activity as well as induction of resident endoplasmic reticulum chaperone proteins, glucose-regulated proteins 78 and 94. The calcium-sensitive chaperone heat shock protein 70 and the cysteine protease m calpain did not respond to resveratrol pretreatment. However, a significant induction of heat shock protein 70 was observed in the contralateral cortex of resveratrol pretreated rats following 4 h of right middle cerebral artery occlusion. These data suggest that resveratrol preconditioning promotes ischemic tolerance in the short term, in part via effects mediated through activation of estrogen and NMDA receptors, as well as through mild activation of cellular stress proteins.
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Affiliation(s)
- M C Saleh
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada
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Saleh MC, Tassetto M, van Rij RP, Goic B, Gausson V, Berry B, Jacquier C, Antoniewski C, Andino R. Antiviral immunity in Drosophila requires systemic RNA interference spread. Nature 2009; 458:346-50. [PMID: 19204732 PMCID: PMC3978076 DOI: 10.1038/nature07712] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Accepted: 12/03/2008] [Indexed: 12/19/2022]
Abstract
Multicellular organisms evolved sophisticated defence systems to confer protection against pathogens. An important characteristic of these immune systems is their ability to act both locally at the site of infection and at distal uninfected locations. In insects, such as Drosophila melanogaster, RNA interference (RNAi) mediates antiviral immunity. However, the antiviral RNAi defence in flies seems to be a local, cell-autonomous process, as flies are thought to be unable to generate a systemic RNAi response. Here we show that a recently defined double-stranded RNA (dsRNA) uptake pathway is essential for effective antiviral RNAi immunity in adult flies. Mutant flies defective in this dsRNA uptake pathway were hypersensitive to infection with Drosophila C virus and Sindbis virus. Mortality in dsRNA-uptake-defective flies was accompanied by 100-to 10(5)-fold increases in viral titres and higher levels of viral RNA. Furthermore, inoculating naked dsRNA into flies elicited a sequence-specific antiviral immune response that required an intact dsRNA uptake pathway. These findings suggest that spread of dsRNA to uninfected sites is essential for effective antiviral immunity. Notably, infection with green fluorescent protein (GFP)-tagged Sindbis virus suppressed expression of host-encoded GFP at a distal site. Thus, similar to protein-based immunity in vertebrates, the antiviral RNAi response in flies also relies on the systemic spread of a virus-specific immunity signal.
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Affiliation(s)
- Maria-Carla Saleh
- Department of Microbiology and Immunology, University of California, San Francisco 94122-2280, USA
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van Rij RP, Saleh MC, Berry B, Foo C, Houk A, Antoniewski C, Andino R. The RNA silencing endonuclease Argonaute 2 mediates specific antiviral immunity in Drosophila melanogaster. Genes Dev 2006; 20:2985-95. [PMID: 17079687 PMCID: PMC1620017 DOI: 10.1101/gad.1482006] [Citation(s) in RCA: 431] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Most organisms have evolved defense mechanisms to protect themselves from viruses and other pathogens. Arthropods lack the protein-based adaptive immune response found in vertebrates. Here we show that the central catalytic component of the RNA-induced silencing complex (RISC), the nuclease Argonaute 2 (Ago-2), is essential for antiviral defense in adult Drosophila melanogaster. Ago-2-defective flies are hypersensitive to infection with a major fruit fly pathogen, Drosophila C virus (DCV), and with Cricket Paralysis virus (CrPV). Increased mortality in ago-2 mutant flies was associated with a dramatic increase in viral RNA accumulation and virus titers. The physiological significance of this antiviral mechanism is underscored by our finding that DCV encodes a potent suppressor of RNA interference (RNAi). This suppressor binds long double-stranded RNA (dsRNA) and inhibits Dicer-2-mediated processing of dsRNA into short interfering RNA (siRNA), but does not bind short siRNAs or disrupt the microRNA (miRNA) pathway. Based on these results we propose that RNAi is a major antiviral immune defense mechanism in Drosophila.
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Affiliation(s)
- Ronald P van Rij
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, CA 94143, USA
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McQuaid TS, Saleh MC, Joseph JW, Gyulkhandanyan A, Manning-Fox JE, MacLellan JD, Wheeler MB, Chan CB. cAMP-mediated signaling normalizes glucose-stimulated insulin secretion in uncoupling protein-2 overexpressing beta-cells. J Endocrinol 2006; 190:669-80. [PMID: 17003268 DOI: 10.1677/joe.1.06723] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We investigated whether an increase in cAMP could normalize glucose-stimulated insulin secretion (GSIS) in uncoupling protein-2 (UCP2) overexpressing (ucp2-OE) beta-cells. Indices of beta-cell (beta-TC-6f7 cells and rodent islets) function were measured after induction of ucp2, in the presence or absence of cAMP-stimulating agents, analogs, or inhibitors. Islets of ob/ob mice had improved glucose-responsiveness in the presence of forskolin. Rat islets overexpressing ucp2 had significantly lower GSIS than controls. Acutely, the protein kinase A (PKA) and epac pathway stimulant forskolin normalized insulin secretion in ucp2-OE rat islets and beta-TC-6f7 beta-cells, an effect blocked by specific PKA inhibitors but not mimicked by epac agonists. However, there was no effect of ucp2-OE on cAMP concentrations or PKA activity. In ucp2-OE islets, forskolin inhibited ATP-dependent potassium (K(ATP)) channel currents and (86)Rb(+) efflux, indicative of K(ATP) block. Likewise, forskolin application increased intracellular Ca(2+), which could account for its stimulatory effects on insulin secretion. Chronic exposure to forskolin increased ucp2 mRNA and exaggerated basal secretion but not GSIS. In mice deficient in UCP2, there was no augmentation of either cAMP content or cAMP-dependent insulin secretion. Thus, elevating cellular cAMP can reverse the deficiency in GSIS invoked by ucp2-OE, at least partly through PKA-mediated effects on the K(ATP) channel.
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Affiliation(s)
- T S McQuaid
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward, C1A 4P3 Canada
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Saleh MC, van Rij RP, Hekele A, Gillis A, Foley E, O’Farrell PH, Andino R. The endocytic pathway mediates cell entry of dsRNA to induce RNAi silencing. Nat Cell Biol 2006; 8. [PMID: 16862146 PMCID: PMC2731564 DOI: 10.1038/ncbl439] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Many metazoan cells can take up exogenous double-stranded (ds) RNA and use it to initiate an RNA silencing response, however, the mechanism for this uptake is ill-defined. Here, we identify the pathway for dsRNA uptake in Drosophila melanogaster S2 cells. Biochemical and cell biological analyses, and a genome-wide screen for components of the dsRNA-uptake machinery, indicated that dsRNA is taken up by an active process involving receptor-mediated endocytosis. Pharmacological inhibition of endocytic pathways disrupted exogenous dsRNA entry and the induction of gene silencing. This dsRNA uptake mechanism seems to be evolutionarily conserved, as knockdown of orthologues in Caenorhabditis elegans inactivated the RNA interference response in worms. Thus, this entry pathway is required for systemic RNA silencing in whole organisms. In Drosophila cells, pharmacological evidence suggests that dsRNA entry is mediated by pattern-recognition receptors. The possible role of these receptors in dsRNA entry may link RNA interference (RNAi) silencing to other innate immune responses.
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Affiliation(s)
- Maria-Carla Saleh
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Ronald P. van Rij
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Armin Hekele
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Amethyst Gillis
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Edan Foley
- Department of Biochemistry and Biophysics, University of California San Francisco, CA 94143-2200, USA
| | - Patrick H. O’Farrell
- Department of Biochemistry and Biophysics, University of California San Francisco, CA 94143-2200, USA
| | - Raul Andino
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
- Correspondence should be addressed to R.A. (e-mail: )
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Saleh MC, van Rij RP, Hekele A, Gillis A, Foley E, O’Farrell PH, Andino R. The endocytic pathway mediates cell entry of dsRNA to induce RNAi silencing. Nat Cell Biol 2006; 8:793-802. [PMID: 16862146 PMCID: PMC2731564 DOI: 10.1038/ncb1439] [Citation(s) in RCA: 355] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 06/06/2006] [Indexed: 02/06/2023]
Abstract
Many metazoan cells can take up exogenous double-stranded (ds) RNA and use it to initiate an RNA silencing response, however, the mechanism for this uptake is ill-defined. Here, we identify the pathway for dsRNA uptake in Drosophila melanogaster S2 cells. Biochemical and cell biological analyses, and a genome-wide screen for components of the dsRNA-uptake machinery, indicated that dsRNA is taken up by an active process involving receptor-mediated endocytosis. Pharmacological inhibition of endocytic pathways disrupted exogenous dsRNA entry and the induction of gene silencing. This dsRNA uptake mechanism seems to be evolutionarily conserved, as knockdown of orthologues in Caenorhabditis elegans inactivated the RNA interference response in worms. Thus, this entry pathway is required for systemic RNA silencing in whole organisms. In Drosophila cells, pharmacological evidence suggests that dsRNA entry is mediated by pattern-recognition receptors. The possible role of these receptors in dsRNA entry may link RNA interference (RNAi) silencing to other innate immune responses.
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Affiliation(s)
- Maria-Carla Saleh
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Ronald P. van Rij
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Armin Hekele
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Amethyst Gillis
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
| | - Edan Foley
- Department of Biochemistry and Biophysics, University of California San Francisco, CA 94143-2200, USA
| | - Patrick H. O’Farrell
- Department of Biochemistry and Biophysics, University of California San Francisco, CA 94143-2200, USA
| | - Raul Andino
- Department of Microbiology and Immunology, University of California San Francisco, CA 94143–2280, USA
- Correspondence should be addressed to R.A. (e-mail: )
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Sow A, Lamant M, Bonny JM, Larvaron P, Piaud O, Lécureuil C, Fontaine I, Saleh MC, Garcia Otin AL, Renou JP, Baron B, Zakin M, Guillou F. Oligodendrocyte differentiation is increased in transferrin transgenic mice. J Neurosci Res 2006; 83:403-14. [PMID: 16400659 DOI: 10.1002/jnr.20741] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transferrin (Tf), the iron transport glycoprotein found in biological fluids of vertebrates, is synthesized mainly by hepatocytes. Tf is also synthesized by oligodendrocytes (Ol), and several lines of evidence indicate that brain Tf could be involved in myelinogenesis. Because Tf is postnatally expressed in the brain, we sought to investigate whether Tf could intervene in Ol differentiation. For this purpose, we analyzed transgenic mice overexpressing the complete human Tf gene in Ol. We show that the hTf transgene was expressed only from 5 days postpartum onward. In the brain of 14-day-old transgenic mice, the DM-20 mRNA level was decreased, whereas the PLP, MBP, CNP, and MAG mRNA levels were increased. We counted a higher proportion of Ol expressing the O4 (Ol-specific antigens) and PLP in brain cells cultured from transgenic mice. These results support the idea that overexpressing Tf in the brain accelerates the oligodendrocyte lineage maturation. Accordingly, by NMR imaging acquisition of diffusion tensor in hTf transgenic mice, we observed early maturation of the cerebellum and spinal cord and more myelination in the corpus callosum. In addition, hTf overexpression led to an increase in Sox10 mRNA and protein. Increases in Sox10 and in Tf expression occur simultaneously during brain development. The Olig1 mRNA level also increased, but long after the rise of hTf and Sox10. The Olig2 mRNA level remained unchanged in the brain of transgenic mice. Our findings suggest that Tf could influence oligodendrocyte progenitor differentiation in the CNS.
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MESH Headings
- 2',3'-Cyclic-Nucleotide Phosphodiesterases/genetics
- 2',3'-Cyclic-Nucleotide Phosphodiesterases/metabolism
- Age Factors
- Analysis of Variance
- Animals
- Animals, Newborn
- Blotting, Northern/methods
- Blotting, Western/methods
- Body Weight/genetics
- Brain/cytology
- Cell Count/methods
- Cell Differentiation/genetics
- Cells, Cultured
- Enzyme-Linked Immunosorbent Assay/methods
- Gene Expression Regulation, Developmental/genetics
- Humans
- Immunohistochemistry/methods
- Magnetic Resonance Imaging/methods
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic/physiology
- Myelin Basic Protein/genetics
- Myelin Basic Protein/metabolism
- Myelin Proteolipid Protein/genetics
- Myelin Proteolipid Protein/metabolism
- Myelin-Associated Glycoprotein
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Oligodendroglia/cytology
- Oligodendroglia/physiology
- RNA, Messenger/isolation & purification
- Radioimmunoassay/methods
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Transferrin/genetics
- Transferrin/metabolism
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Affiliation(s)
- Amina Sow
- Unité Physiologie de la Reproduction et des Comportements (PRC), Institut National de la Recherche Agronomique, UMR 6175 INRA-CNRS-Université de Tours-Haras Nationaux, Nouzilly, France
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Abstract
RNA interference or RNA silencing is a dsRNA guided mechanism that mediates sequence specific degradation of RNA. The recent demonstration that RNA interference can be used to inhibit virus replication has initiated an exciting field of research: first, as a potential novel antiviral therapeutic approach and, second, as a tool for dissecting virus-host interactions. Here we review and discuss the current data and perspectives on the use of RNA interference in the study of poliovirus as a model for positive strand RNA viruses.
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Affiliation(s)
- Maria-Carla Saleh
- Department of Microbiology and Immunology, University of California, 513 Parnassus Avenue, Box 0414, San Francisco, CA 94143-2280, USA
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Lécureuil C, Saleh MC, Fontaine I, Baron B, Zakin MM, Guillou F. Transgenic mice as a model to study the regulation of human transferrin expression in Sertoli cells. Hum Reprod 2004; 19:1300-7. [PMID: 15105395 DOI: 10.1093/humrep/deh297] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Understanding the regulation of proteins secreted by human Sertoli cells is important for identifying the causes of infertility in men. However, experiments with Sertoli cells purified from healthy testes are difficult to perform, for obvious ethical reasons. Therefore, experiments with transgenic mouse models could provide an alternative approach to study the function and regulation of a human gene in Sertoli cells. METHODS To validate this approach, transgenic mice were generated using phage P1 containing an 80 kbp insert encompassing the complete human transferrin (hTf) gene. The expression pattern of hTf in the mouse background was analysed by isolating Sertoli cells from transgenic mice and comparing the regulation of the human and mouse Tf genes by hormones, retinoids and a cytokine in vitro. RESULTS The hTf gene in transgenic mice shows a tissue-specific expression pattern that mimics the pattern observed in the human. In Sertoli cell cultures, FSH, insulin, retinol or tumour necrosis factor-alpha (TNF-alpha) stimulated hTf secretion, while testosterone alone had no effect. A combination of FSH, insulin, retinol and testosterone or a combination of TNF-alpha and retinol stimulated hTf secretion, but no additive effect was observed. CONCLUSION Besides their well-known advantages, transgenic mice seem to be useful models to recapitulate the normal regulation of a human gene.
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Affiliation(s)
- C Lécureuil
- UMR 6175 Institut National de la Recherche Agronomique, Centre National de Recherche Scientifique, Université de Tours, Haras Nationaux 'Physiologie de la Reproduction et des Comportements', 37380 Nouzilly, Paris, France
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Crotty S, Saleh MC, Gitlin L, Beske O, Andino R. The poliovirus replication machinery can escape inhibition by an antiviral drug that targets a host cell protein. J Virol 2004; 78:3378-86. [PMID: 15016860 PMCID: PMC371039 DOI: 10.1128/jvi.78.7.3378-3386.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viral replication depends on specific interactions with host factors. For example, poliovirus RNA replication requires association with intracellular membranes. Brefeldin A (BFA), which induces a major rearrangement of the cellular secretory apparatus, is a potent inhibitor of poliovirus RNA replication. Most aspects governing the relationship between viral replication complex and the host membranes remain poorly defined. To explore these interactions, we used a genetic approach and isolated BFA-resistant poliovirus variants. Mutations within viral proteins 2C and 3A render poliovirus resistant to BFA. In the absence of BFA, viruses containing either or both of these mutations replicated similarly to wild type. In the presence of BFA, viruses carrying a single mutation in 2C or 3A exhibited an intermediate-growth phenotype, while the double mutant was fully resistant. The viral proteins 2C and 3A have critical roles in both RNA replication and vesicle formation. The identification of BFA resistant mutants may facilitate the identification of cellular membrane-associated proteins necessary for induction of vesicle formation and RNA replication. Importantly, our data underscore the dramatic plasticity of the host-virus interactions required for successful viral replication.
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Affiliation(s)
- Shane Crotty
- Department of Microbiology and Immunology, University of California-San Francisco, San Francisco, California 94143-2280, USA
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43
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Saleh MC, Espinosa de los Monteros A, de Arriba Zerpa GA, Fontaine I, Piaud O, Djordjijevic D, Baroukh N, Garcia Otin AL, Ortiz E, Lewis S, Fiette L, Santambrogio P, Belzung C, Connor JR, de Vellis J, Pasquini JM, Zakin MM, Baron B, Guillou F. Myelination and motor coordination are increased in transferrin transgenic mice. J Neurosci Res 2003; 72:587-94. [PMID: 12749023 DOI: 10.1002/jnr.10619] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Myelin deficiency in the central nervous system (CNS) can cause severe disabling conditions. Most of the transgenic mice models overexpressing myelin components have limitations for investigators of myelin deficiency and myelin therapy as they severely alter CNS architecture. It has been postulated that transferrin (Tf) is involved in oligodendrocyte (OL) maturation and myelinogenesis. Because Tf is not an intrinsic myelin constituent, we decided to investigate if its overexpression could have an impact on the myelination process without affecting myelin integrity. We generated transgenic mice containing the complete human Tf gene specifically overexpressed in OLs. This overexpression leads to more than a 30% increase in myelin components, such as galactolipids, phospholipids, and proteins. Electron microscopy showed that myelin is structurally normal in terms of thickness and compaction. Behavior analysis showed that mice do not display significant modifications in their locomotion and cognitive and emotional abilities. Furthermore, in one of the genetic background, animals presented a significant increase in motor coordination. We did not find any modification in OL number during early postnatal development, suggesting that Tf does not act on OL proliferation. In addition, the levels of iron and ferritin remained unchanged in the brain of transgenic mice compared to control mice. Our findings indicate that, besides its known iron transport function, Tf is able to influence myelination process and induce behavioral improvements in mice.
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Affiliation(s)
- Maria-Carla Saleh
- Unité d'Expression des Gènes Eucaryotes, Institut Pasteur, Paris, France
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Abstract
Hypertrophy of beta cells from obese fa/fa rats is associated with increased sensitivity to basal glucose. Exposure to glucose in culture distorts insulin secretion more in beta cells from large than small islets from fa/fa rats. The aim of the present study is to investigate whether increased beta cell volume is associated with both glucose hypersensitivity and altered activity of the glucose-sensitive anion conductance. Beta cells from fa/fa rats had increased volume compared with those from lean rats after 24 h culture. Three-day exposure to 25 mM glucose in culture induced 10-15% hypertrophy in beta cells from lean rats and basal secretion from intact islets was increased tenfold. Estimates of ion channel activity were made from measurement of radiolabeled ion efflux. Taurine efflux, a marker of glucose-regulated anion channel activity, was reduced after high glucose exposure but no alterations in glucose-dependent K+ efflux were detected. The reverse hemolytic plaque assay was used to determine the contributions of the number of secreting cells (recruitment) versus secretion per cell in beta cells from enlarged (>250 microm diameter), intermediate (125-250 microm) and small (<125 microm) islets from lean and obese rats exposed to conditions mimicking hyperglycemia. After overnight culture, basal secretion was twofold greater from beta cells of large fa/fa islets compared with all other groups. Recruitment at low glucose was increased in all lean or fa/fa beta cells derived from >125 microm islets. When beta cells from small islets were exposed to supra-physiological glucose for 3 days, recruitment was increased at basal glucose and blunted at high glucose. Glucose exposure converts the recruitment profile of beta cells from small islets to resemble that of beta cells from large islets while inducing cellular hypertrophy and reduced anion conductance. However, hypertrophy alone did not predict functional characteristics of overnight-cultured beta cells from fa/fa rats.
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Affiliation(s)
- C B Chan
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, C1A 4P3 Canada.
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45
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Abstract
Uncoupling protein-2, discovered in 1997, belongs to a family of inner mitochondrial membrane proteins that, in general, function as carriers. The function(s) of uncoupling protein-2 have not yet been definitively described. However, mounting evidence suggests that uncoupling protein-2 could act in multiple tissues as a regulator of lipid metabolism. A role as a modulator of reactive oxygen species as a defence against infection is also postulated. In this review, a brief overview of the general and specific properties of uncoupling protein-2 is given and evidence for metabolic and immune regulatory functions is summarized. Uncoupling protein-2 could have particular importance in the regulation of lipid metabolism in adipose tissue and skeletal muscle. In addition, its ability to inhibit insulin secretion could also promote fat utilization over storage. Inhibition by uncoupling protein-2 of reactive oxygen species formation in macrophages and other tissues could have implications for regulation of immune function. The possibility of functions of uncoupling protein-2 in other tissues such as the brain are beginning to emerge.
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Affiliation(s)
- M C Saleh
- Department of Anatomy and Physiology, University of Prince Edward Island, Charlottetown, PE I, Canada
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46
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Abstract
In the present investigation, electrophysiological recordings of thalamic relay neurons were used to investigate the role of estrogen as a modulator of visceral afferent information through the PBN to forebrain structures. Experiments were done in anaesthetized (sodium thiobutabarbitol; 100 mg/kg) male and ovariectomized female rats supplemented for 7 days prior with either 17beta-estradiol (OVX-E(2)) or saline (OVX-S). A portion of the right cervical vagus was isolated for the electrical activation (0.8 Hz, 2 ms duration) of visceral afferents. The evoked single and multi-unit activity was recorded via a recording electrode in the ventrobasal thalamus. Exogenous microinjection of 17beta-estradiol (0.1, 0.25 and 0.5 microM; 200 nl) into the parabrachial nucleus (PBN) produced a significant, dose-dependent attenuation in the magnitude of visceral afferent activation-evoked responses of neurons recorded in the thalamus in both male and OVX-E(2) groups. No effect on evoked thalamic activity was observed following injection of estrogen into the PBN of OVX-S animals. Co-injection of estrogen with the GABA(A) receptor antagonist, bicuculine (0.1 microM; 200 nl) but not phaclofen (GABA(B); 0.1, 0.5 or 1 microM; 200 nl) resulted in an increase in the evoked thalamic response in males (55+/-11%) and OVX-E(2) female (68+/-15%) rats. These studies suggest that estrogen inhibits neurotransmission in the PBN via an interaction with the GABA(A) receptor to modulate the flow of visceral information to the thalamus.
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Affiliation(s)
- T M Saleh
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, PEI Health Research Institute, Charlottetown, P.E.I., Canada C1A 4P3.
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47
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Abstract
The current investigation examines the effect of acute and chronic estrogen administration on baroreflex sensitivity and autonomic tone following 2 h of vagal afferent stimulation in ovariectomized female rats. Female Sprague-Dawley rats were ovariectomized and supplemented daily for 7 days with either estrogen (OVX-E2; 0.5 microg/kg; s.c.) or saline (OVX-S; 0.9%; s.c.). On the 8th day the animals were anaesthetized (sodium thiobutabarbitol; 100 mg/kg) and instrumented for recording blood pressure, heart rate and efferent vagal and renal nerve activities. The baroreflex was evoked using intravenous injection of various doses of phenylephrine hydrochloride (0.025, 0.05+/-0.1 mg/kg). Electrical stimulation of vagal afferents for 2 h produces autonomic imbalance characterized by sympathoexcitation and parasympathetic withdrawal. This protocol of vagal stimulation produced a significant increase in renal nerve activity (from 20+/-6 to 140+/-20 spikes/2 s) and decreases in both vagal nerve activity (from 22+/-3 to 10+/-2 spikes/2 s) and baroreflex sensitivity (from 0.55+/-0.05 to 0.3+/-0.05) in OVX-S female rats. However. vagal stimulation had no effect on baroreflex sensitivity or autonomic nerve activities in OVX-E2 rats. Administration of a single, bolus dose of estrogen (1 x 10(-2) mg/kg) to OVX-S rats immediately prior to termination of vagal stimulation blocked the changes in autonomic nerve activities and baroreflex sensitivity previously observed. These results suggest that both chronic and acute estrogen supplementation may provide resistance to the autonomic disturbances associated with visceral afferent activation.
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Affiliation(s)
- T M Saleh
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
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48
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Abstract
Among the many benefits of long-term hormone replacement therapy to postmenopausal women is a significant reduction in risk for and progression of cardiovascular disease. However, long-term estrogen replacement therapy has been associated with several undesirable, and likely dose-dependent, side-effects. There is some evidence to suggest that the dose of estrogen which confers optimal beneficial effects on the cardiovascular system is much lower than that which is currently prescribed for postmenopausal women. The following experiments were conducted to determine the dose-response relationship of acutely administered estrogen on autonomic tone and reflex control of heart rate in ovariectomized Sprague-Dawley female rats. Rats were anaesthetized with sodium thiobutabarbital (100 mg/kg) and instrumented to record blood pressure, heart rate and efferent parasympathetic and sympathetic nerve activities. The sensitivity of the cardiac baroreflex was tested using intravenous injection of either phenylephrine hydrochloride (0.025-0.1 mg/kg) or sodium nitroprusside (0.0025-0.01 mg/kg). Intravenous injection of estrogen produced dose-dependent increases in the magnitude of the baroreflex sensitivity and parasympathetic tone while reducing sympathetic tone with a maximal effect observed at 1 x 10(-3) mg/kg. Prior administration of the selective estrogen receptor antagonist, ICI 182,780 blocked the estrogen-induced changes in baroreflex sensitivity and autonomic tone. These results demonstrate that acutely administered, low-dose estrogen has beneficial effects on autonomic tone and cardiovascular reflexes.
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Affiliation(s)
- T M Saleh
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
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49
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Abstract
The role of estrogen in central autonomic nuclei was examined in ovariectomized female Sprague-Dawley rats supplemented daily for 7 days with either estrogen (5 microg/kg; sc) or saline (0.9%; sc). Animals were subsequently anaesthetized with sodium thiobutabarbital (Inactin; 100 mg/kg; ip) and instrumented to record blood pressure and heart rate. Efferent vagal parasympathetic (VPNA) and renal sympathetic (RSNA) nerve activities were recorded and used to assess baseline and reflexive changes in autonomic tone. The cardiac baroreflex was evoked using a single bolus injection of phenylephrine (0.1 mg/kg) both before and following either intrathecal injection of estrogen (0.5 microM; 1 microl) or bilateral injection of estrogen (0.5 microM; 100 nl/side) into several central autonomic nuclei. In estrogen-replaced rats, both the baseline and PE-evoked values for mean arterial pressure and RSNA were significantly decreased following injection of estrogen into the nucleus tractus solitarius (NTS), rostral ventrolateral medulla (RVLM), parabrachial nucleus (PBN), central nucleus of the amygdala (CNA) and the intrathecal space. Baseline heart rate and VPNA were significantly decreased following injection of estrogen into NTS, nucleus ambiguous (Amb), PBN and the intrathecal space. PE-evoked changes in heart rate and VPNA were significantly enhanced following injection of estrogen into these same nuclei. Injection of estrogen into the insular cortex (IC) produced significant decreases in baseline and PE-evoked RSNA only. The cardiac baroreflex was significantly enhanced following injection of estrogen into all nuclei and the intrathecal space. In saline-replaced females, injection of estrogen into NTS, RVLM, Amb and the intrathecal space had similar effects on both baseline and PE-evoked parameters although of a reduced magnitude compared to estrogen-replaced rats. However, no significant changes in autonomic tone and baroreflex function were observed following the injection of estrogen into the PBN, CNA or IC of saline-replaced rats. These results demonstrate a role for estrogen in central autonomic nuclei in female rats and suggest a possible alteration of estrogen receptor distribution or efficacy within the central nervous system of estrogen-deficient female rats.
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Affiliation(s)
- M C Saleh
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, P.E.I., C1A 4P3, Charlottetown, Canada
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50
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de Arriba Zerpa GA, Saleh MC, Fernández PM, Guillou F, Espinosa de los Monteros A, de Vellis J, Zakin MM, Baron B. Alternative splicing prevents transferrin secretion during differentiation of a human oligodendrocyte cell line. J Neurosci Res 2000; 61:388-95. [PMID: 10931525 DOI: 10.1002/1097-4547(20000815)61:4<388::aid-jnr5>3.0.co;2-q] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Transferrin, the iron-transport protein of vertebrate serum, is synthesized mainly in the liver, from which it is secreted into the blood. Transferrin is also synthesized in oligodendrocytes and is an early marker of their differentiation. We have analyzed the regulation of transferrin expression in HOG cells, a human oligodendrocyte cell line. Transferrin expression was correlated with the appearance of oligodendrocyte differentiation markers when cells were exposed to differentiation medium. In contrast to the protein expressed in hepatocytes or in Sertoli cells, transferrin was secreted by neither HOG cells nor immature rat primary oligodendrocytes in vitro. Moreover, transferrin appears to be localized in the cytosol and not in the secretory compartment, as is expected for secreted proteins. This transferrin localization was correlated with the synthesis of a specific transcript, resulting from an alternative splicing, which leads to the elimination of the signal peptide sequence. These results suggest the existence of a functional difference between transferrin synthesized in the brain and in other organs such as liver and testis. They are in accordance with the hypothesis that transferrin plays a specific role, other than iron transport, in oligodendrocyte maturation and in the myelination process.
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