Annexin A2 is involved in the formation of hepatitis C virus replication complex on the lipid raft.
The hepatitis C virus (HCV) RNA replicates in hepatic cells by forming a replication complex on the lipid raft (detergent-resistant membrane [DRM]). Replication complex formation requires various viral nonstructural (NS) proteins as well as host cellular proteins. In our previous study (C. K. Lai, K. S. Jeng, K. Machida, and M. M. Lai, J. Virol. 82:8838-8848, 2008), we found that a cellular protein, annexin A2 (Anxa2), interacts with NS3/NS4A. Since NS3/NS4A is a membranous protein and Anxa2 is known as a lipid raft-associated scaffold protein, we postulate that Anxa2 helps in the formation of the HCV replication complex on the lipid raft. Further studies showed that Anxa2 was localized at the HCV-induced membranous web and interacted with NS4B, NS5A, and NS5B and colocalized with them in the perinuclear region. The silencing of Anxa2 decreased the formation of membranous web-like structures and viral RNA replication. Subcellular fractionation and bimolecular fluorescence complementation analysis revealed that Anxa2 was partially associated with HCV at the lipid raft enriched with phosphatidylinositol-4-phosphate (PI4P) and caveolin-2. Further, the overexpression of Anxa2 in HCV-nonsusceptible HEK293 cells caused the enrichment of HCV NS proteins in the DRM fraction and increased the colony-forming ability of the HCV replicon. Since Anxa2 is known to induce the formation of the lipid raft microdomain, we propose that Anxa2 recruits HCV NS proteins and enriches them on the lipid raft to form the HCV replication complex.
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
Vikas
V
Saxena
Chao-Kuen
CK
Lai
Ti-Chun
TC
Chao
King-Song
KS
Jeng
Michael M C
MM
Lai
D017306:Annexin A2 / Q000235:genetics / Q000378:metabolism*; D051243:Caveolin 2 / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism / Q000821:virology; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism* / Q000648:ultrastructure; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000378:metabolism; D014779:Virus Replication; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; D012324:RNA-Dependent RNA Polymerase
D017306:Annexin A2; D051243:Caveolin 2; D018129:Phosphatidylinositol Phosphates; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C037178:phosphatidylinositol 4-phosphate; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase