Requirement of NOX2 and Reactive Oxygen Species for Efficient RIG-I-Mediated Antiviral Response through Regulation of MAVS Expression

The innate immune response is essential to the host defense against viruses, through restriction of virus replication and coordination of the adaptive immune response. Induction of antiviral genes is a tightly regulated process initiated mainly through sensing of invading virus nucleic acids in the cytoplasm by RIG-I like helicases, RIG-I or Mda5, which transmit the signal through a common mitochondria-associated adaptor, MAVS. Although major breakthroughs have recently been made, much remains unknown about the mechanisms that translate virus recognition into antiviral genes expression. Beside the reputed detrimental role, reactive oxygen species (ROS) act as modulators of cellular signaling and gene regulation. NADPH oxidase (NOX) enzymes are a main source of deliberate cellular ROS production. Here, we found that NOX2 and ROS are required for the host cell to trigger an efficient RIG-I-mediated IRF-3 activation and downstream antiviral IFNβ and IFIT1 gene expression. Additionally, we provide evidence that NOX2 is critical for the expression of the central mitochondria-associated adaptor MAVS. Taken together these data reveal a new facet to the regulation of the innate host defense against viruses through the identification of an unrecognized role of NOX2 and ROS

Androgen-Regulated Expression of Arginase 1, Arginase 2 and Interleukin-8 in Human Prostate Cancer

BACKGROUND: Prostate cancer (PCa) is the most frequently diagnosed cancer in North American men. Androgen-deprivation therapy (ADT) accentuates the infiltration of immune cells within the prostate. However, the immunosuppressive pathways regulated by androgens in PCa are not well characterized. Arginase 2 (ARG2) expression by PCa cells leads to a reduced activation of tumor-specific T cells. Our hypothesis was that androgens could regulate the expression of ARG2 by PCa cells. METHODOLOGY/PRINCIPAL FINDINGS: In this report, we demonstrate that both ARG1 and ARG2 are expressed by hormone-sensitive (HS) and hormone-refractory (HR) PCa cell lines, with the LNCaP cells having the highest arginase activity. In prostate tissue samples, ARG2 was more expressed in normal and non-malignant prostatic tissues compared to tumor tissues. Following androgen stimulation of LNCaP cells with 10 nM R1881, both ARG1 and ARG2 were overexpressed. The regulation of arginase expression following androgen stimulation was dependent on the androgen receptor (AR), as a siRNA treatment targeting the AR inhibited both ARG1 and ARG2 overexpression. This observation was correlated in vivo in patients by immunohistochemistry. Patients treated by ADT prior to surgery had lower ARG2 expression in both non-malignant and malignant tissues. Furthermore, ARG1 and ARG2 were enzymatically active and their decreased expression by siRNA resulted in reduced overall arginase activity and l-arginine metabolism. The decreased ARG1 and ARG2 expression also translated with diminished LNCaP cells cell growth and increased PBMC activation following exposure to LNCaP cells conditioned media. Finally, we found that interleukin-8 (IL-8) was also upregulated following androgen stimulation and that it directly increased the expression of ARG1 and ARG2 in the absence of androgens. CONCLUSION/SIGNIFICANCE: Our data provides the first detailed in vitro and in vivo account of an androgen-regulated immunosuppressive pathway in human PCa through the expression of ARG1, ARG2 and IL-8

The Biobanque québécoise de la COVID-19 (BQC19)—A cohort to prospectively study the clinical and biological determinants of COVID-19 clinical trajectories

SARS-CoV-2 infection causing the novel coronavirus disease 2019 (COVID–19) has been responsible for more than 2.8 million deaths and nearly 125 million infections worldwide as of March 2021. In March 2020, the World Health Organization determined that the COVID–19 outbreak is a global pandemic. The urgency and magnitude of this pandemic demanded immediate action and coordination between local, regional, national, and international actors. In that mission, researchers require access to high-quality biological materials and data from SARS-CoV-2 infected and uninfected patients, covering the spectrum of disease manifestations. The “Biobanque québécoise de la COVID-19” (BQC19) is a pan–provincial initiative undertaken in Québec, Canada to enable the collection, storage and sharing of samples and data related to the COVID-19 crisis. As a disease-oriented biobank based on high-quality biosamples and clinical data of hospitalized and non-hospitalized SARS-CoV-2 PCR positive and negative individuals. The BQC19 follows a legal and ethical management framework approved by local health authorities. The biosamples include plasma, serum, peripheral blood mononuclear cells and DNA and RNA isolated from whole blood. In addition to the clinical variables, BQC19 will provide in-depth analytical data derived from the biosamples including whole genome and transcriptome sequencing, proteome and metabolome analyses, multiplex measurements of key circulating markers as well as anti-SARS-CoV-2 antibody responses. BQC19 will provide the scientific and medical communities access to data and samples to better understand, manage and ultimately limit, the impact of COVID-19. In this paper we present BQC19, describe the process according to which it is governed and organized, and address opportunities for future research collaborations. BQC19 aims to be a part of a global communal effort addressing the challenges of COVID–19

La kinase IKKε

La kinase IKKε, membre atypique de la famille des kinases IKK, a récemment été reconnue comme étant un oncogène majeur surexprimé dans une large proportion de cancers du sein. Outre son rôle dans la régulation du facteur de transcription NF-κB, dont l’action dans le développement du cancer du sein est largement établie, IKKε participe à la phosphorylation de divers substrats. L’identification de certains de ces substrats a permis de trouver des voies oncogéniques qui pourraient constituer des cibles thérapeutiques. De plus, IKKε semble jouer un rôle dans la résistance au tamoxifène. Ces nouvelles données ouvrent des perspectives prometteuses en vue de la mise au point de thérapies ciblant IKKε dans les cancers du sein

CSV2018: The 2nd Symposium of the Canadian Society for Virology

The 2nd Symposium of the Canadian Society for Virology (CSV2018) was held in June 2018 in Halifax, Nova Scotia, Canada, as a featured event marking the 200th anniversary of Dalhousie University. CSV2018 attracted 175 attendees from across Canada and around the world, more than double the number that attended the first CSV symposium two years earlier. CSV2018 provided a forum to discuss a wide range of topics in virology including human, veterinary, plant, and microbial pathogens. Invited keynote speakers included David Kelvin (Dalhousie University and Shantou University Medical College) who provided a historical perspective on influenza on the 100th anniversary of the 1918 pandemic; Sylvain Moineau (Université Laval) who described CRISPR-Cas systems and anti-CRISPR proteins in warfare between bacteriophages and their host microbes; and Kate O’Brien (then from Johns Hopkins University, now relocated to the World Health Organization where she is Director of Immunization, Vaccines and Biologicals), who discussed the underlying viral etiology for pneumonia in the developing world, and the evidence for respiratory syncytial virus (RSV) as a primary cause. Reflecting a strong commitment of Canadian virologists to science communication, CSV2018 featured the launch of Halifax’s first annual Soapbox Science event to enable public engagement with female scientists, and the live-taping of the 499th episode of the This Week in Virology (TWIV) podcast, hosted by Vincent Racaniello (Columbia University) and science writer Alan Dove. TWIV featured interviews of CSV co-founders Nathalie Grandvaux (Université de Montréal) and Craig McCormick (Dalhousie University), who discussed the origins and objectives of the new society; Ryan Noyce (University of Alberta), who discussed technical and ethical considerations of synthetic virology; and Kate O’Brien, who discussed vaccines and global health. Finally, because CSV seeks to provide a better future for the next generation of Canadian virologists, the symposium featured a large number of oral and poster presentations from trainees and closed with the awarding of presentation prizes to trainees, followed by a tour of the Halifax Citadel National Historic Site and an evening of entertainment at the historic Alexander Keith’s Brewery

Virus Infection Triggers MAVS Polymers of Distinct Molecular Weight

The mitochondrial antiviral signaling (MAVS) adaptor protein is a central signaling hub required for cells to mount an antiviral response following virus sensing by retinoic acid-inducible gene I (RIG-I)-like receptors. MAVS localizes in the membrane of mitochondria and peroxisomes and in mitochondrial-associated endoplasmic reticulum membranes. Structural and functional studies have revealed that MAVS activity relies on the formation of functional high molecular weight prion-like aggregates. The formation of protein aggregates typically relies on a dynamic transition between oligomerization and aggregation states. The existence of intermediate state(s) of MAVS polymers, other than aggregates, has not yet been documented. Here, we used a combination of non-reducing SDS-PAGE and semi-denaturing detergent agarose gel electrophoresis (SDD-AGE) to resolve whole cell extract preparations to distinguish MAVS polymerization states. While SDD-AGE analysis of whole cell extracts revealed the formation of previously described high molecular weight prion-like aggregates upon constitutively active RIG-I ectopic expression and virus infection, non-reducing SDS-PAGE allowed us to demonstrate the induction of lower molecular weight oligomers. Cleavage of MAVS using the NS3/4A protease revealed that anchoring to intracellular membranes is required for the appropriate polymerization into active high molecular weight aggregates. Altogether, our data suggest that RIG-I-dependent MAVS activation involves the coexistence of MAVS polymers with distinct molecular weights

Respiratory Syncytial Virus and Cellular Stress Responses: Impact on Replication and Physiopathology

Human respiratory syncytial virus (RSV), a member of the Paramyxoviridae family, is a major cause of severe acute lower respiratory tract infection in infants, elderly and immunocompromised adults. Despite decades of research, a complete integrated picture of RSV-host interaction is still missing. Several cellular responses to stress are involved in the host-response to many virus infections. The endoplasmic reticulum stress induced by altered endoplasmic reticulum (ER) function leads to activation of the unfolded-protein response (UPR) to restore homeostasis. Formation of cytoplasmic stress granules containing translationally stalled mRNAs is a means to control protein translation. Production of reactive oxygen species is balanced by an antioxidant response to prevent oxidative stress and the resulting damages. In recent years, ongoing research has started to unveil specific regulatory interactions of RSV with these host cellular stress responses. Here, we discuss the latest findings regarding the mechanisms evolved by RSV to induce, subvert or manipulate the ER stress, the stress granule and oxidative stress responses. We summarize the evidence linking these stress responses with the regulation of RSV replication and the associated pathogenesis

Binding of Kaposi's Sarcoma-Associated Herpesvirus K-bZIP to Interferon-Responsive Factor 3 Elements Modulates Antiviral Gene Expression▿

Kaposi's sarcoma-associated herpesvirus encodes numerous regulatory proteins capable of modulating viral and cellular gene expression and affecting host cell functions. K-bZIP, a leucine zipper-containing transcription factor encoded by ORFK8, is one such protein. During infection, transcription of the ORFK8 early gene is turned on by the immediate-early replication and transcription factor activator (RTA). One described function of the K-bZIP nuclear protein is to interact with and repress RTA-mediated transactivation of viral promoters, including that of the K8 gene. In the present work, we provide evidence that the expression of K-bZIP results in the activation of the ifn-β gene. Of interest, ifn-β gene activation by K-bZIP is independent of interferon (IFN)-responsive factor 3 (IRF-3) and nuclear factor κB (NF-κB) activation. Using a DNA binding affinity assay and electromobility shift assay, we report that K-bZIP binds efficiently to the PRDIII-I region of the beta IFN (IFN-β) promoter, and, in doing so, it prevents the attachment of activated IRF-3 but not that of NF-κB or ATF2/c-Jun to the IFN-β promoter sequence. As a consequence, ifn-β gene activation in response to IFN inducers such as Sendai virus infection or expression of retinoic acid-inducible gene I, mitochondrial antiviral signaling protein, or TANK-binding kinase 1 (TBK-1) is severely impaired (>90%) by the presence of K-bZIP. K-bZIP also prevents the activation of RANTES and CXCL11, whose promoters are also regulated by IRF-3. Lysine 158 (target for SUMO conjugation), threonine 111, and serine 167 (targets for phosphorylation) mutants of K-bZIP were equally effective as wild-type K-bZIP in mediating the repression of TBK-1-activated ifn-β gene expression. Lastly, the overexpression of CREB binding protein could not reverse the K-bZIP repression of TBK-1-activated ifn-β gene expression. In all, our results indicate that K-bZIP binds directly to the PRDIII-I region of the IFN-β promoter and, as a consequence, causes a low level of ifn-β gene transcription. In doing so, K-bZIP prevents IRF-3 from binding to the IFN-β promoter and precludes the formation of the enhanceosome, which is required for maximal ifn-β gene transcription. A new role for K-bZIP as a protein involved in immune evasion is therefore uncovered

Interleukin (IL)-6 Inhibits IL-27- and IL-30-Mediated Inflammatory Responses in Human Monocytes

Interleukin (IL)-30, the IL-27p28 subunit of the heterodimeric cytokine IL-27, acts as an antagonist of IL-27 and IL-6 signaling in murine cells via glycoprotein 130 (gp130) receptor and additional binding partners. Thus far, functions of IL-30 have not been fully elucidated in human cells. We demonstrate that like IL-27, IL-30 upregulated TLR4 expression to enhance lipopolysaccharide-induced TNF-α production in human monocytes; however, these IL-30-mediated activities did not reach the same levels of cytokine induction compared to IL-27. Interestingly, IL-30- and IL-27-mediated interferon-γ-induced protein 10 (IP-10) production required WSX-1 engagement and signal transducer and activator of transcription (STAT) 3 phosphorylation; furthermore, IL-30 induced STAT phosphorylation after 16 h, whereas IL-27 induced STAT phosphorylation within 30 min. This prompted us to examine if a secondary mediator was required for IL-30-induced pro-inflammatory functions, and hence we examined IL-6-related molecules. Combined with inhibition of soluble IL-6 receptor α (sIL-6Rα) and data showing that IL-6 inhibited IL-30/IL-27-induced IP-10 expression, we demonstrate a role for sIL-6Rα and gp130 in IL-30-mediated activity in human cells