Реферат
ER-phagy is a form of autophagy, which is mediated by ER-phagy receptors and selectively degrades endoplasmic reticulum (ER). RNA viruses have been shown to utilize the ER as a membrane source to establish their replication organelles double-membrane vesicles (DMVs). However, whether viruses modulate ER-phagy to drive viral DMV formation and its underlying molecular mechanisms remain largely unknown. Here, we demonstrate that coronavirus subverts ER-phagy by hijacking the ER-phagy receptors FAM134B and ATL3 into p62 condensates, resulting in increased viral replication. Mechanistically, we show that viral protein ORF8 binds to and undergoes condensation with p62. FAM134B and ATL3 interact with homodimer of ORF8 and are aggregated into ORF8/p62 liquid droplets, leading to ER-phagy inhibition. ORF8/p62 condensates disrupt ER-phagy to facilitate viral DMV formation and activates ER stress. Together, our data highlight how coronavirus modulates ER-phagy to drive viral replication by hijacking ER-phagy receptors. Graphical abstract Tan et al. describe an important mechanism by which SARS-CoV-2 protein ORF8 inhibits ER-phagy by hijacking the receptors FAM134B and ATL3 into p62 condensates, facilitating the production of viral replication organelle double membrane vesicles.
Реферат
ER-phagy is a form of autophagy that is mediated by ER-phagy receptors and selectively degrades endoplasmic reticulum (ER). Coronaviruses have been shown to use the ER as a membrane source to establish their double-membrane vesicles (DMVs). However, whether viruses modulate ER-phagy to drive viral DMV formation and its underlying molecular mechanisms remains largely unknown. Here, we demonstrate that coronavirus subverts ER-phagy by hijacking the ER-phagy receptors FAM134B and ATL3 into p62 condensates, resulting in increased viral replication. Mechanistically, we show that viral protein ORF8 binds to and undergoes condensation with p62. FAM134B and ATL3 interact with homodimer of ORF8 and are aggregated into ORF8/p62 liquid droplets, leading to ER-phagy inhibition. ORF8/p62 condensates disrupt ER-phagy to facilitate viral DMV formation and activate ER stress. Together, our data highlight how coronavirus modulates ER-phagy to drive viral replication by hijacking ER-phagy receptors.
Реферат
As an enveloped virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains a membrane protein (M) that mediates viral release from cellular membranes. However, the molecular mechanisms of SARS-CoV-2 virion release remain poorly understood. In the present study, we performed RNA interference (RNAi) screening and identified the E3 ligase RNF5, which mediates the ubiquitination of SARS-CoV-2 M at residue K15 to enhance the interaction of the viral envelope protein (E) with M, whereas the deubiquitinating enzyme POH1 negatively regulates this process. The M-E complex ensures the uniform size of viral particles for viral maturation and mediates virion release. Moreover, M traffics from the Golgi apparatus to autophagosomes and uses autophagosomes for virion release, and this process is dependent on RNF5-mediated ubiquitin modification and M-E interaction. These results demonstrate that ubiquitin modification of SARS-CoV-2 M stabilizes the M-E complex and uses autophagosomes for virion release. IMPORTANCE Enveloped virus particles are released from the membranes of host cells, and viral membrane proteins (M) are critical for this process. A better understanding of the molecular mechanisms of SARS-CoV-2 assembly and budding is critical for the development of antiviral therapies. Envelope protein (E) and M of SARS-CoV-2 form complexes to mediate viral assembly and budding. RNF5 was identified to play a role as the E3 ligase, and POH1 was demonstrated to function as the deubiquitinating enzyme of SARS-CoV-2 M. The two components collectively regulate the interaction of M with E to promote viral assembly and budding. Ubiquitinated M uses autophagosomes for viral release. Our findings provide insights into the mechanisms of SARS-CoV-2 assembly and budding, demonstrating the importance of ubiquitination modification and autophagy in viral replication.
Реферат
Importance: Ocular manifestations and outcomes in children with confirmed coronavirus disease 2019 (COVID-19), relevant affecting factors, and differences in ocular disease between children and adults have yet to be fully understood. Objective: To investigate ocular manifestations and clinical characteristics of children with laboratory-confirmed COVID-19. Design, Setting, and Participants: This cross-sectional study was conducted at Wuhan Children's Hospital in Wuhan, China. Children with COVID-19 confirmed by severe acute respiratory syndrome coronavirus disease 2 nucleic acid tests of upper respiratory tract specimens between January 26 and March 18, 2020, were included. Main Outcomes and Measures: Onset clinical symptoms and duration, ocular symptoms, and needs for medication. Results: A total of 216 pediatric patients were included, among whom 134 (62%) were boys, with a median (interquartile range) age of 7.25 (2.6-11.6) years. Based on the exposure history, 193 children (89.4%) had a confirmed (173 [80.1%]) or suspected (20 [9.3%]) family member with COVID-19 infection. The most common symptoms among symptomatic children were fever (81 [37.5%]) and cough (79 [36.6%]). Of 216 children, 93 (43.1%) had no systemic or respiratory symptoms. All children with mild (101 [46.8%]) or moderate (115 [53.2%]) symptoms recovered without reported death. Forty-nine children (22.7%) showed various ocular manifestations, of which 9 had ocular complaints being the initial manifestations of COVID-19. The common ocular manifestations were conjunctival discharge (27 [55.1%]), eye rubbing (19 [38.8%]), and conjunctival congestion (5 [10.2%]). Children with systemic symptoms (29.3% vs 14.0%; difference, 15.3%; 95% CI, 9.8%-20.7%; P = .008) or with cough (31.6% vs 17.5%; difference, 14.1%; 95% CI, 8.0%-20.3%; P = .02) were more likely to develop ocular symptoms. Ocular symptoms were typically mild, and children recovered or improved. Conclusions and Relevance: In this cross-sectional study, children hospitalized with COVID-19 in Wuhan, China, presented with a series of onset symptoms including fever, cough, and ocular manifestations, such as conjunctival discharge, eye rubbing, and conjunctival congestion. Patients' systemic clinical symptoms or cough were associated with ocular symptoms. Ocular symptoms recovered or improved eventually.