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Qu Y, Wang X, Zhu Y, Wang W, Wang Y, Hu G, Liu C, Li J, Ren S, Xiao MZX, Liu Z, Wang C, Fu J, Zhang Y, Li P, Zhang R, Liang Q. ORF3a-Mediated Incomplete Autophagy Facilitates Severe Acute Respiratory Syndrome Coronavirus-2 Replication. Front Cell Dev Biol 2021; 9:716208. [PMID: 34386498 PMCID: PMC8353283 DOI: 10.3389/fcell.2021.716208] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/05/2021] [Indexed: 12/23/2022] Open
Abstract
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the causative agent for the coronavirus disease 2019 (COVID-19) pandemic and there is an urgent need to understand the cellular response to SARS-CoV-2 infection. Beclin 1 is an essential scaffold autophagy protein that forms two distinct subcomplexes with modulators Atg14 and UVRAG, responsible for autophagosome formation and maturation, respectively. In the present study, we found that SARS-CoV-2 infection triggers an incomplete autophagy response, elevated autophagosome formation but impaired autophagosome maturation, and declined autophagy by genetic knockout of essential autophagic genes reduces SARS-CoV-2 replication efficiency. By screening 26 viral proteins of SARS-CoV-2, we demonstrated that expression of ORF3a alone is sufficient to induce incomplete autophagy. Mechanistically, SARS-CoV-2 ORF3a interacts with autophagy regulator UVRAG to facilitate PI3KC3-C1 (Beclin-1-Vps34-Atg14) but selectively inhibit PI3KC3-C2 (Beclin-1-Vps34-UVRAG). Interestingly, although SARS-CoV ORF3a shares 72.7% amino acid identity with the SARS-CoV-2 ORF3a, the former had no effect on cellular autophagy response. Thus, our findings provide the mechanistic evidence of possible takeover of host autophagy machinery by ORF3a to facilitate SARS-CoV-2 replication and raise the possibility of targeting the autophagic pathway for the treatment of COVID-19.
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Affiliation(s)
- Yafei Qu
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xin Wang
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yunkai Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Science, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Weili Wang
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuyan Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Science, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Gaowei Hu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Science, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Chengrong Liu
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jingjiao Li
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shanhui Ren
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Science, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Maggie Z X Xiao
- Faculty of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Zhenshan Liu
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chunxia Wang
- Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Joyce Fu
- Department of Statistics, University of California, Riverside, Riverside, CA, United States
| | - Yucai Zhang
- Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Ping Li
- Key Laboratory for Food Microbial Technology of Zhejiang Province, Zhejiang Gongshang University, Hangzhou, China
| | - Rong Zhang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Science, Shanghai Medical College, Biosafety Level 3 Laboratory, Fudan University, Shanghai, China
| | - Qiming Liang
- Research Center of Translational Medicine, Shanghai Institute of Immunology, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
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Novel Role of vBcl2 in the Virion Assembly of Kaposi's Sarcoma-Associated Herpesvirus. J Virol 2018; 92:JVI.00914-17. [PMID: 29167347 DOI: 10.1128/jvi.00914-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022] Open
Abstract
The viral Bcl-2 homolog (vBcl2) of Kaposi's sarcoma-associated herpesvirus (KSHV) displays efficient antiapoptotic and antiautophagic activity through its central BH3 domain, which functions to prolong the life span of virus-infected cells and ultimately enhances virus replication and latency. Independent of its antiapoptotic and antiautophagic activity, vBcl2 also plays an essential role in KSHV lytic replication through its amino-terminal amino acids (aa) 11 to 20. Here, we report a novel molecular mechanism of vBcl2-mediated regulation of KSHV lytic replication. vBcl2 specifically bound the tegument protein open reading frame 55 (ORF55) through its amino-terminal aa 11 to 20, allowing their association with virions. Consequently, the vBcl2 peptide derived from vBcl2 aa 11 to 20 effectively disrupted the interaction between vBcl2 and ORF55, inhibiting the incorporation of the ORF55 tegument protein into virions. This study provides new insight into vBcl2's function in KSHV virion assembly that is separable from its inhibitory role in host apoptosis and autophagy.IMPORTANCE KSHV, an important human pathogen accounting for a large percentage of virally caused cancers worldwide, has evolved a variety of stratagems for evading host immune responses to establish lifelong persistent infection. Upon viral infection, infected cells can go through programmed cell death, including apoptosis and autophagy, which plays an effective role in antiviral responses. To counter the host response, KSHV vBcl2 efficiently blocks apoptosis and autophagy to persist for the life span of virus-infected cells. Besides its anti-programmed-cell-death activity, vBcl2 also interacts with the ORF55 tegument protein for virion assembly in infected cells. Interestingly, the vBcl2 peptide disrupts the vBcl2-ORF55 interaction and effectively inhibits KSHV virion assembly. This study indicates that KSHV vBcl2 harbors at least three genetically separable functions to modulate both host cell death signaling and virion production and that the vBcl2 peptide can be developed as an anti-KSHV therapeutic application.
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