Biology subjects

Hage, A.

Publications and source records attributed to Hage, A..

8 recordsLinked to original sources

bioRxiv2026

Epigenetic regulation of DPP4 receptor expression by NONO enables replication of MERS-CoV

Middle East respiratory syndrome coronavirus (MERS-CoV), first reported in 2012, belongs to the Betacoronavirus genus, including SARS-CoV and SARS-CoV-2. Human-to-human transmission of MERS-CoV appears inefficient, but repeated spillover events have been reported from at least 27 countries, raising concern for future emergent events. Coronaviruses (CoVs) rely extensively on host proteins to support their replication. Several studies have implicated the paraspeckle non-POU domain-containing octamer-binding protein (NONO) as an RNA-binding protein (RBP) that binds to CoV genomes, but the role of this protein in regulating replication is unknown. Here, we show that NONO is required for expression of dipeptidyl peptidase 4 (DPP4, also known as CD26), the major cellular receptor required for MERS-CoV attachment and entry. NONO did not impact DPP4 mRNA processing or stability but instead promoted DPP4 transcription through control of active H3K4me3 and repressive H3K27me3 histone modifications at the DPP4 locus. Together, these findings identify NONO as a key proviral host factor for MERS-CoV and reveal an epigenetic mechanism linking a host RBP to viral entry receptor expression that may represent a target for therapeutic strategies.

microbiology↗

bioRxiv2026

The paraspeckle protein NONO potentiates the antiviral innate immune response through chromatin regulation

Type-I interferons (IFN-I) and IFN-stimulated genes (ISGs) are central to antiviral defense, while dysregulation can drive autoimmunity. IFNB1 expression is controlled by a highly ordered multiprotein complex composed of IRF3/7, NF{kappa}B, and ATF2/c-Jun (AP-1) that recruit coactivators and chromatin-remodeling proteins to expose the IFNB1 promoter for the RNA polymerase II (RNA Pol II) transcriptional machinery. Here, we identified the paraspeckle protein non-POU domain-containing octamer-binding protein (NONO) as a critical facilitator of innate immune activation. Loss of NONO enhanced replication of multiple orthoflaviviruses including West Nile virus due to impaired induction of IFN-I and ISGs. NONO did not affect upstream signaling but instead promoted chromatin accessibility and promoter access for RNA Pol II to drive expression of IFNB1, ISGs, and proinflammatory cytokines. These findings position NONO as a key regulator of antiviral gene expression and reveal chromatin-levels of control that determine effective antiviral immunity.

immunology↗

bioRxiv2026

Restraint of Powassan virus replication by TRIM5α facilitates viral avoidance of antiviral immunity

TRIpartite Motif (TRIM) protein 5 alpha (TRIM5) is a well characterized cellular inhibitor of lentivirus replication that limits transmission of related viruses between primates. We previously reported that TRIM5 derived from humans and rhesus macaques inhibits replication of orthoflaviviruses belonging to the tick-borne encephalitis virus (TBEV) serocomplex, including TBEV, Kyasanur forest disease virus and Langat virus (LGTV), but interestingly not the tick-borne Powassan virus (POWV). To further characterize the primate TRIM5 and orthoflavivirus interface, we screened TRIM5 variants from representative old- and new-world primates for restriction capacity. TRIM5 from old-world African green monkey, De Brazzas monkey and chimpanzee demonstrated virus-specific restriction of tick-borne orthoflaviviruses. Efforts to determine why TRIM5 fails to inhibit POWV revealed that our lab stock had acquired a non-synonymous mutation in NS3 that, when introduced into a POWV molecular clone, facilitated virus replication in the presence of all inhibitory primate TRIM5 proteins. Infection of human dendritic cells with TRIM5-resistant POWV resulted in high early replication and strong induction of interferon responses that limited replication compared with the wild-type virus. Thus, primate TRIM5 functions as a potent cellular barrier to infection with tick-borne orthoflaviviruses that restrains replication to a level that may help avoid early innate immune recognition.

microbiology↗

bioRxiv2024

TRIM7 ubiquitinates SARS-CoV-2 membrane protein to limit apoptosis and viral replication

SARS-CoV-2 is a highly transmissible virus that causes COVID-19 disease. Mechanisms of viral pathogenesis include excessive inflammation and viral-induced cell death, resulting in tissue damage. We identified the host E3-ubiquitin ligase TRIM7 as an inhibitor of apoptosis and SARS-CoV-2 replication via ubiquitination of the viral membrane (M) protein. Trim7-/- mice exhibited increased pathology and virus titers associated with epithelial apoptosis and dysregulated immune responses. Mechanistically, TRIM7 ubiquitinates M on K14, which protects cells from cell death. Longitudinal SARS-CoV-2 sequence analysis from infected patients revealed that mutations on M-K14 appeared in circulating variants during the pandemic. The relevance of these mutations was tested in a mouse model. A recombinant M- K14/K15R virus showed reduced viral replication, consistent with the role of K15 in virus assembly, and increased levels of apoptosis associated with the loss of ubiquitination on K14. TRIM7 antiviral activity requires caspase-6 inhibition, linking apoptosis with viral replication and pathology.

microbiology↗

bioRxiv2021

A novel mechanism of regulation of the transcription factor GLI3 by toll-like receptor signaling

The transcription factor GLI3 is a member of the GLI family and has been shown to be regulated by canonical hedgehog (HH) signaling through smoothened (SMO). Little is known about SMO-independent regulation of GLI3. Here, we identify TLR signaling as a novel pathway regulating GLI3 expression. We show that GLI3 expression is induced by LPS/TLR4 in human monocyte cell lines and peripheral blood CD14+ cells. Further analysis identified TRIF, but not MyD88, signaling as the adapter used by TLR4 to regulate GLI3. Using pharmacological and genetic tools, we identified IRF3 as the transcription factor regulating GLI3 downstream of TRIF. Furthermore, using additional TLR ligands that signal exclusively through TRIF such as the TLR4 ligand, MPLA and the TLR3 ligand, Poly(I:C), we confirm the role of TRIF-IRF3 in the regulation of GLI3. We found that IRF3 directly binds to the GLI3 promoter region and this binding was increased upon stimulation of TRIF-IRF3 with Poly(I:C). Furthermore, using IRF3-/- MEFs, we found that Poly(I:C) stimulation no longer induced GLI3 expression. Finally, using macrophages from mice lacking Gli3 expression in myeloid cells (M-Gli3-/-), we found that in the absence of Gli3, LPS stimulated macrophages secrete less CCL2 and TNF- compared with macrophages from wild-type (WT) mice. Taken together, these results identify a novel TLR-TRIF-IRF3 pathway that regulates the expression of GLI3 that regulates inflammatory cytokines and expands our understanding of the non-canonical signaling pathways involved in the regulation of GLI transcription factors.

immunology↗

bioRxiv2020

Topoisomerase III-beta is required for efficient replication of positive-sense RNA viruses

Based on genome-scale loss-of-function screens we discovered that Topoisomerase III-{beta} (TOP3B), a human topoisomerase that acts on DNA and RNA, is required for yellow fever virus and dengue virus-2 replication. Remarkably, we found that TOP3B is required for efficient replication of all positive-sense-single stranded RNA viruses tested, including SARS-CoV-2. While there are no drugs that specifically inhibit this topoisomerase, we posit that TOP3B is an attractive anti-viral target.

microbiology↗

bioRxiv2019

VAMP8 contributes to TRIM6-mediated type-I interferon antiviral response during West Nile virus infection

Several members of the tripartite motif (TRIM) family of E3 ubiquitin ligases regulate immune pathways including the antiviral type I interferon (IFN-I) system. Previously, we demonstrated that TRIM6 is involved in IFN-I induction and signaling. In the absence of TRIM6, optimal IFN-I signaling is reduced, allowing increased replication of interferon-sensitive viruses. Despite having evolved numerous mechanisms to restrict the vertebrate hosts IFN-I response, West Nile Virus (WNV) replication is sensitive to pre-treatment with IFN-I. However, the regulators and products of the IFN-I pathway that are important in regulating WNV replication are incompletely defined. Consistent with WNVs sensitivity to IFN-I, we found that in TRIM6 knockout (TRIM6-KO) A549 cells WNV replication is significantly increased and IFN-I induction and signaling is impaired compared to wild-type (wt) cells. IFN{beta} pre-treatment was more effective in protecting against subsequent WNV infection in wt cells as compared to TRIM6-KO, indicating that TRIM6 contributes to the establishment of an IFN-induced antiviral response against WNV. Using next generation sequencing, we identified VAMP8 as a potential factor involved in this TRIM6-mediated antiviral response. VAMP8 knockdown resulted in reduced Jak1 and STAT1 phosphorylation and impaired induction of several ISGs following WNV infection or IFN{beta} treatment. Furthermore, VAMP8-mediated STAT1 phosphorylation required the presence of TRIM6. Therefore, the VAMP8 protein is a novel regulator of IFN-I signaling, and its expression and function is dependent on TRIM6 activity. Overall, these results provide evidence that TRIM6 contributes to the antiviral response against WNV and identified VAMP8 as a novel regulator of the IFN-I system.\n\nIMPORTANCEWNV is a mosquito-borne flavivirus that poses threat to human health across large discontinuous areas throughout the world. Infection with WNV results in febrile illness, which can progress to severe neurological disease. Currently, there are no approved treatment options to control WNV infection. Understanding the cellular immune responses that regulate viral replication is important in diversifying the resources available to control WNV. Here we show that the elimination of TRIM6 in human cells results in an increase in WNV replication and alters the expression and function of other components of the IFN-I pathway through VAMP8. Dissecting the interactions between WNV and host defenses both informs basic molecular virology and promotes the development of host- and viral-targeted antiviral strategies.

immunology↗

bioRxiv2019

Peptidoglycan associated cyclic lipopeptide disrupts viral infectivity

Enteric viruses exploit bacterial components including lipopolysaccharides (LPS) and peptidoglycan (PG) to facilitate infection in humans. With origins in the bat enteric system, we wondered if severe acute respiratory syndrome-coronavirus (SARS-CoV) or Middle East respiratory syndrome-CoV (MERS-CoV) also use bacterial components to modulate infectivity. To test this question, we incubated CoVs with LPS and PG and evaluated infectivity finding no change following LPS treatment. However, PG from B. subtilis reduced infection >10,000-fold while PG from other bacterial species failed to recapitulate this. Treatment with an alcohol solvent transferred inhibitory activity to the wash and mass spectrometry revealed surfactin, a cyclic lipopeptide antibiotic, as the inhibitory compound. This antibiotic had robust dose- and temperature-dependent inhibition of CoV infectivity. Mechanistic studies indicated that surfactin disrupts CoV virion integrity and surfactin treatment of the virus inoculum ablated infection in vivo. Finally, similar cyclic lipopeptides had no effect on CoV infectivity and the inhibitory effect of surfactin extended broadly to enveloped viruses including influenza, Ebola, Zika, Nipah, Chikungunya, Una, Mayaro, Dugbe, and Crimean-Congo hemorrhagic fever viruses. Overall, our results indicate that peptidoglycan-associated surfactin has broad virucidal activity and suggest bacteria byproducts may negatively modulate virus infection.\n\nImportanceIn this manuscript, we considered a role for bacteria in shaping coronavirus infection. Taking cues from studies of enteric viruses, we initially investigated how bacterial surface components might improve CoV infection. Instead, we found that peptidoglycan-associated surfactin is a potent viricidal compound that disrupts virion integrity with broad activity against enveloped viruses. Our results indicate that interactions with commensal bacterial may improve or disrupt viral infections highlighting the importance of understanding these microbial interactions and their implications for viral pathogenesis and treatment.

microbiology↗