Daniel A. Donahue

Department of Virology

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IFITM proteins inhibit placental syncytiotrophoblast formation and promote fetal demise

Science (2019)

Julian Buchrieser Séverine A. Degrelle Thérèse Couderc Quentin Nevers Olivier Disson

Placenta formation and fetal demise A critical step of placental development is the fusion of trophoblast cells into a multi-nucleated syncytiotrophoblast layer. Trophoblast fusion is mediated by syncytins, encoded by endogenous retrovirus–derived envelope glycoproteins. Buchrieser et al. report that interferon-induced transmembrane (IFITM) proteins inhibit syncytin-mediated syncytiotrophoblast formation, restricting placental development and triggering fetal demise (see the Perspective by Kellam and Weiss). The results provide a molecular explanation for the placental dysfunctions observed in interferon-mediated disorders such as intrauterine growth retardation, TORCH (toxoplasmosis, other, rubella, cytomegalovirus, and herpes) infections, and some forms of preeclampsia. Science , this issue p. 176 ; see also p. 118

Syncytiotrophoblasts

Syncytium

Trophoblast

Cell fusion

Multinucleate

Interferon type I

Syncytiotrophoblasts

10.1126/science.aaw7733

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Citations (124)

Innovations to Address Complex Challenges: 22^ndAnnual Canadian Conference on HIV/AIDS Research

Canadian Journal of Infectious Diseases and Medical Microbiology (2013)

Jonathan B. Angel Robert S. Hogg Mark Hull Neora Pick Ma Luo

With a membership of more than 1,000 researchers and others interested in HIV research, the Canadian Association for HIV Research (CAHR) is the leading organization of HIV/AIDS researchers in Canada.The annual CAHR conference is the premier gathering in Canada for those working in the field of HIV, as well as policy makers, persons living with HIV, and other individuals committed to ending the pandemic.It is a chance to assess where we are, evaluate recent scientific developments, and together chart a course forward.This year's programme will present new scientific knowledge and offer many opportunities for structured dialogue on the major issues facing the global response to HIV.A variety of sessions such as abstract-driven presentations, symposia, and plenaries will meet the needs of various participants.Other related activities, including ancillary meetings and the New Investigator Workshop, will contribute to an exceptional opportunity for professional development and networking.CAHR 2013 will be a tremendous opportunity for researchers and community members from coast to coast to share the latest scientific advances in the field, learn from one another's expertise, and develop new ways to treat and prevent HIV.I hope you enjoy the conference, find it to be a worthwhile learning experience, and thank you in advance for your contributions, participation, and continued support.MESSAgE FROM THE CAHR pRESIDENT / MESSAgE DU pRÉSIDENT DE L'ACRV B ienvenue au 22 e Congrès canadien annuel de recherche sur le VIH/sida (congrès de l'ACRV 2013)!Comptant plus de 1 000 membres -des chercheurs et d'autres personnes s'intéressant à la recherche sur le VIH -, l'Association canadienne de recherche sur le VIH (ACRV) est un organisme canadien de premier plan se consacrant à la recherche sur le VIH/sida.Le congrès annuel de l'ACRV est l'événement le plus important au pays s'adressant aux personnes oeuvrant dans le domaine du VIH ainsi qu'aux décideurs, aux personnes vivant avec le VIH et aux autres personnes participant à la lutte contre la pandémie.Il offre une occasion de faire le point sur la situation, d'évaluer les récents progrès scientifiques et d'élaborer un plan d'action.Le congrès de cette année présentera les nouvelles connaissances scientifiques et permettra de discuter dans un cadre structuré des principaux enjeux liés à la lutte mondiale contre le VIH.Un éventail de séances telles que des présentations d'abrégés, des colloques et des séances plénières répondra aux besoins des différents participants.D'autres activités connexes, dont des réunions auxiliaires et l'atelier des nouveaux chercheurs dans le domaine du VIH, constitueront d'excellentes occasions de perfectionnement professionnel et de réseautage.À l'occasion du congrès de l'ACRV 2013, les chercheurs et les membres des collectivités d'un océan à l'autre pourront comme jamais échanger sur les plus récentes percées scientifiques, apprendre des autres et établir de nouvelles façons de traiter et de prévenir le VIH.J'espère que le congrès vous plaira et qu'il sera pour vous une expérience d'apprentissage utile.Merci d'avance pour vos contributions, votre participation et votre appui soutenu.

10.1155/2013/849649

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Expression of Nef from unintegrated HIV-1 DNA downregulates cell surface CXCR4 and CCR5 on T-lymphocytes

Retrovirology (2010)

Richard D. Sloan Daniel A. Donahue Björn D. Kuhl Tamara Bar-Magen Mark A. Wainberg

Abstract Background Transcription of HIV-1 cDNA prior to, or in the absence of, integration leads to synthesis of all classes of viral RNA transcripts. Yet only a limited range of viral proteins, including Nef, are translated in this context. Nef expression from unintegrated HIV-1 DNA has been shown to reduce cell surface CD4 levels in T-cells. We wished to determine whether Nef expressed from unintegrated DNA was also able to downregulate the chemokine coreceptors CXCR4 and CCR5. Viral integration was blocked through use of an inactive integrase or by using the integrase inhibitor raltegravir. Infected cells bearing unintegrated DNA were assayed by flow cytometry in the GFP reporter cell line, Rev-CEM, for cell surface levels of CD4, CXCR4 and CCR5. Results In cells bearing only unintegrated HIV-1 DNA, we found that surface levels of CXCR4 were significantly reduced, while levels of CCR5 were also diminished, but not to the extent of CXCR4. We also confirmed the downregulation of CD4. Similar patterns of results were obtained with both integrase-deficient virus or with wild-type infections of cells treated with raltegravir. The Alu-HIV qPCR assay that we used for detection of proviral DNA did not detect any integrated viral DNA. Conclusions Our results demonstrate that Nef can be expressed from unintegrated DNA at functionally relevant levels and suggest a role for Nef in downregulation of CXCR4 and CCR5. These findings may help to explain how downregulation of CXCR4, CCR5 and CD4 might restrict superinfection and/or prevent signal transduction involving HIV-1 infected cells.

Raltegravir

Integrase inhibitor

10.1186/1742-4690-7-44

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Citations (37)

Tetherin restricts direct cell-to-cell infection of HIV-1

Retrovirology (2010)

Björn D. Kuhl Richard D. Sloan Daniel A. Donahue Tamara Bar-Magen Chen Liang

Abstract Background Tetherin (BST-2/CD317/HM1.24) is an interferon (IFN)-inducible factor of the innate immune system, recently shown to exert antiviral activity against HIV-1 and other enveloped viruses by tethering nascent viral particles to the cell surface, thereby inhibiting viral release. In HIV-1 infection, the viral protein U (Vpu) counteracts this antiviral action by down-modulating tetherin from the cell surface. Viral dissemination between T-cells can occur via cell-free transmission or the more efficient direct cell-to-cell route through lipid raft-rich virological synapses, to which tetherin localizes. Results We established a flow cytometry-based co-culture assay to distinguish viral transfer from viral transmission and investigated the influence of tetherin on cell-to-cell spread of HIV-1. Sup-T1 cells inducible for tetherin expression were used to examine the impact of effector and target cell tetherin expression on virus transfer and transmission. Using this assay, we showed that tetherin inhibits direct cell-to-cell virus transfer and transmission. Viral Vpu promoted viral transmission from tetherin-expressing cells by down-modulating tetherin from the effector cell surface. Further, we showed that tetherin on the target cell promotes viral transfer and transmission. Viral infectivity in itself was not affected by tetherin. Conclusion In addition to inhibiting viral release, tetherin also inhibits direct cell-to-cell spread. Viral protein Vpu counteracts this restriction, outweighing its possible cost of fitness in cell-to-cell transmission. The differential role of tetherin in effector and target cells suggest a role for tetherin in cell-cell contacts and virological synapses.

Tetherin

10.1186/1742-4690-7-115

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Citations (96)

Comparative biochemical analysis of HIV-1 subtype B and C integrase enzymes

Retrovirology (2009)

Tamara Bar-Magen Richard D. Sloan Verena Faltenbacher Daniel A. Donahue Björn D. Kuhl

Abstract Background Integrase inhibitors are currently being incorporated into highly active antiretroviral therapy (HAART). Due to high HIV variability, integrase inhibitor efficacy must be evaluated against a range of integrase enzymes from different subtypes. Methods This study compares the enzymatic activities of HIV-1 integrase from subtypes B and C as well as susceptibility to various integrase inhibitors in vitro . The catalytic activities of both enzymes were analyzed in regard to each of 3' processing and strand transfer activities both in the presence and absence of the integrase inhibitors raltegravir (RAL), elvitegravir (EVG), and MK-2048. Results Our results show that integrase function is similar with enzymes of either subtype and that the various integrase strand transfer inhibitors (INSTIs) that were employed possessed similar inhibitory activity against both enzymes. Conclusion This suggests that the use of integrase inhibitors against HIV-1 subtype C will result in comparable outcomes to those obtained against subtype B infections.

Raltegravir

Elvitegravir

Integrase inhibitor

Dolutegravir

Integrases

10.1186/1742-4690-6-103

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Citations (46)

SUN2 Silencing Impairs CD4 T Cell Proliferation and Alters Sensitivity to HIV-1 Infection Independently of Cyclophilin A

Journal of Virology (2017)

Daniel A. Donahue Françoise Porrot Norbert Couespel Olivier Schwartz

Linker of nucleoskeleton and cytoskeleton (LINC) complexes connect the nucleus to the cytoskeleton in eukaryotic cells. We previously reported that the overexpression of SUN2, an inner nuclear membrane protein and LINC complex component, inhibits HIV infection between the steps of reverse transcription and nuclear import in a capsid-specific manner. We also reported that SUN2 silencing does not modulate HIV infection in several cell lines. Silencing of SUN2 was recently reported to decrease HIV infection of CD4 T cells, an effect which was suggested to result from modulation of cyclophilin A (CypA)-dependent steps of HIV infection. We confirm here that HIV infection of primary CD4 T cells is compromised in the absence of endogenous SUN2, and we extend these findings to additional viral strains. However, we find that CypA is not required for the decreased infection observed in SUN2-silenced cells and, conversely, that endogenous SUN2 is not required for the well-documented positive modulation of HIV infection by CypA. In contrast, CD4 T cells lacking SUN2 exhibit a considerable defect in proliferative capacity and display reduced levels of activation markers and decreased viability. Additionally, SUN2-silenced CD4 T cells that become infected support reduced levels of viral protein expression. Our results demonstrate that SUN2 is required for the optimal activation and proliferation of primary CD4 T cells and suggest that the disruption of these processes explains the contribution of endogenous SUN2 to HIV infection in primary lymphocytes.IMPORTANCE Linker of nucleoskeleton and cytoskeleton (LINC) complexes connect the nucleus to the cytoskeleton. We previously reported that the overexpression of the LINC complex protein SUN2 inhibits HIV infection by targeting the viral capsid and blocking infection before the virus enters the nucleus. A recent report showed that the depletion of endogenous SUN2 in primary CD4 T cells results in decreased HIV infection and that this involves cyclophilin A (CypA), a host protein that interacts with the capsid of HIV to promote infection. We confirm that HIV infection is reduced in CD4 T cells lacking SUN2, but we find no role for CypA. Instead, SUN2 silencing results in CD4 T cells with decreased viability and much lower proliferation rates. Our results show that SUN2 is required for optimal CD4 T cell activation and proliferation and explain the reduced level of HIV infection in the absence of SUN2.

Cypa

10.1128/jvi.02303-16

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Citations (26)

Biochemical evidence of HIV-1 subtype B and C different patterns of resistance to integrase inhibitors

AIDS (2010)

Tamara Bar-Magen Numhauser Daniel A. Donahue Emily M McDonough Björn D. Kuhl Verena Faltenbacher

Integrase inhibitor

Source

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SUN2 Overexpression Deforms Nuclear Shape and Inhibits HIV

Journal of Virology (2016)

Daniel A. Donahue Sonia Amraoui Francesca Di Nunzio Camille Kieffer Françoise Porrot

In a previous screen of putative interferon-stimulated genes, SUN2 was shown to inhibit HIV-1 infection in an uncharacterized manner. SUN2 is an inner nuclear membrane protein belonging to the linker of nucleoskeleton and cytoskeleton complex. We have analyzed here the role of SUN2 in HIV infection. We report that in contrast to what was initially thought, SUN2 is not induced by type I interferon, and that SUN2 silencing does not modulate HIV infection. However, SUN2 overexpression in cell lines and in primary monocyte-derived dendritic cells inhibits the replication of HIV but not murine leukemia virus or chikungunya virus. We identified HIV-1 and HIV-2 strains that are unaffected by SUN2, suggesting that the effect is specific to particular viral components or cofactors. Intriguingly, SUN2 overexpression induces a multilobular flower-like nuclear shape that does not impact cell viability and is similar to that of cells isolated from patients with HTLV-I-associated adult T-cell leukemia or with progeria. Nuclear shape changes and HIV inhibition both mapped to the nucleoplasmic domain of SUN2 that interacts with the nuclear lamina. This block to HIV replication occurs between reverse transcription and nuclear entry, and passaging experiments selected for a single-amino-acid change in capsid (CA) that leads to resistance to overexpressed SUN2. Furthermore, using chemical inhibition or silencing of cyclophilin A (CypA), as well as CA mutant viruses, we implicated CypA in the SUN2-imposed block to HIV infection. Our results demonstrate that SUN2 overexpression perturbs both nuclear shape and early events of HIV infection.Cells encode proteins that interfere with viral replication, a number of which have been identified in overexpression screens. SUN2 is a nuclear membrane protein that was shown to inhibit HIV infection in such a screen, but how it blocked HIV infection was not known. We show that SUN2 overexpression blocks the infection of certain strains of HIV before nuclear entry. Mutation of the viral capsid protein yielded SUN2-resistant HIV. Additionally, the inhibition of HIV infection by SUN2 involves cyclophilin A, a protein that binds the HIV capsid and directs subsequent steps of infection. We also found that SUN2 overexpression substantially changes the shape of the cell's nucleus, resulting in many flower-like nuclei. Both HIV inhibition and deformation of nuclear shape required the domain of SUN2 that interacts with the nuclear lamina. Our results demonstrate that SUN2 interferes with HIV infection and highlight novel links between nuclear shape and viral infection.

10.1128/jvi.03202-15

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Citations (46)

HIV Fusion in Dendritic Cells Occurs Mainly at the Surface and Is Limited by Low CD4 Levels

Journal of Virology (2017)

Lise Chauveau Daniel A. Donahue Blandine Monel Françoise Porrot Timothée Bruel

ABSTRACT HIV-1 poorly infects monocyte-derived dendritic cells (MDDCs). This is in large part due to SAMHD1, which restricts viral reverse transcription. Pseudotyping HIV-1 with vesicular stomatitis virus G protein (VSV-G) strongly enhances infection, suggesting that earlier steps of viral replication, including fusion, are also inefficient in MDDCs. The site of HIV-1 fusion remains controversial and may depend on the cell type, with reports indicating that it occurs at the plasma membrane or, conversely, in an endocytic compartment. Here, we examined the pathways of HIV-1 entry in MDDCs. Using a combination of temperature shift and fusion inhibitors, we show that HIV-1 fusion mainly occurs at the cell surface. We then asked whether surface levels or intracellular localization of CD4 modulates HIV-1 entry. Increasing CD4 levels strongly enhanced fusion and infection with various HIV-1 isolates, including reference and transmitted/founder strains, but not with BaL, which uses low CD4 levels for entry. Overexpressing coreceptors did not facilitate viral infection. To further study the localization of fusion events, we generated CD4 mutants carrying heterologous cytoplasmic tails (LAMP1 or Toll-like receptor 7 [TLR7]) to redirect the molecule to intracellular compartments. The intracellular CD4 mutants did not facilitate HIV-1 fusion and replication in MDDCs. Fusion of an HIV-2 isolate with MDDCs was also enhanced by increasing surface CD4 levels. Our results demonstrate that MDDCs are inefficiently infected by various HIV-1 and HIV-2 strains, in part because of low CD4 levels. In these cells, viral fusion occurs mainly at the surface, and probably not after internalization. IMPORTANCE Dendritic cells (DCs) are professional antigen-presenting cells inducing innate and adaptive immune responses. DCs express the HIV receptor CD4 and are potential target cells for HIV. There is debate about the sensitivity of DCs to productive HIV-1 and HIV-2 infection. The fusion step of the viral replication cycle is inefficient in DCs, and the underlying mechanisms are poorly characterized. We show that increasing the levels of CD4 at the plasma membrane allows more HIV fusion and productive infection in DCs. We further demonstrate that HIV fusion occurs mainly at the cell surface and not in an intracellular compartment. Our results help us understand why DCs are poorly sensitive to HIV infection.

Cell fusion

10.1128/jvi.01248-17

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Citations (18)

Faculty Opinions recommendation of Directly infected resting CD4+T cells can produce HIV Gag without spreading infection in a model of HIV latency.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature (2012)

Mark A. Wainberg Daniel A. Donahue

10.3410/f.717956420.793461120

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