title: Association of heat-shock protein 70 with lipid rafts is required for Japanese encephalitis virus infection in Huh7 cells.
abstract: Japanese encephalitis virus (JEV) is an enveloped flavivirus and the most common agent of viral encephalitis. It enters cells through receptor-mediated endocytosis and low pH-triggered membrane fusion. Although lipid rafts, cholesterol-enriched lipid-ordered membrane domains, have been shown to participate in JEV entry, the mechanisms of the early events of JEV infection, including the cellular receptors of JEV, remain largely unknown. In the current study, it was demonstrated that heat-shock protein 70 (HSP70), rather than other members of the HSP70 family, was required for JEV entry into a human cell line. Cell-surface expression of HSP70 and a direct interaction between JEV envelope (E) protein and HSP70 were observed. Biochemical fractionation showed that HSP70 clearly migrated into the raft fraction after virus infection and co-fractioned with E protein. Depletion of cholesterol shifted the E protein and HSP70 to a non-raft membrane and decreased JEV entry without affecting virus binding to host cells. Notably, recruitment of HSP70 into lipid rafts was required for activation of the phosphoinositide 3-kinase/Akt signalling pathway in the early stage of JEV infection. These results indicate that lipid rafts facilitate JEV entry, possibly by providing a convenient platform to concentrate JEV and its receptors on the host-cell membrane.
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Yong-Zhe
authors.initials: YZ
authors.lastname: Zhu
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Ming-Mei
authors.initials: MM
authors.lastname: Cao
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Wen-Bo
authors.initials: WB
authors.lastname: Wang
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Ren
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Department of Microbiology, Shanghai Key Laboratory of Medical Biodefense, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Zhong-Tian
authors.initials: ZT
authors.lastname: Qi
mesh_terms: D002460:Cell Line; D004664:Encephalitis Virus, Japanese / Q000235:genetics / Q000502:physiology*; D004672:Encephalitis, Japanese / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism* / Q000821:virology; D011485:Protein Binding; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism; D053585:Virus Attachment
chemical_list: D018840:HSP70 Heat-Shock Proteins; D008563:Membrane Lipids; D014759:Viral Envelope Proteins