Significance of palmitoylation of CD81 on its association with tetraspanin-enriched microdomains and mediating hepatitis C virus cell entry.

CD81, a co-receptor for hepatitis C virus (HCV), is a member of the tetraspanin superfamily and is heavily palmitoylated in the juxtamembrane cysteine residues. Palmitoylation plays an important role in protein-protein interactions and association with cholesterol-rich domains of membranes. In this study, Huh7 cells expressing wild-type or palmitoylation-defective CD81 were generated to analyze whether palmitoylation of CD81 is involved in HCV cell entry. Our data showed that de-palmitoylation of CD81 dramatically reduced its association with tetraspanin CD151, but did not influence CD81 partition in detergent-resistant membranes. Moreover, de-palmitoylated CD81 decreased the host cell susceptibility to HCV. Notably, CD151-specific antibodies and siRNA inhibited HCV cell entry, and detachment of CD81 with CD151 decreased the lateral movement of virus particle/CD81 complex to areas of cell-cell contact. These results suggest that palmitoylation of CD81 should facilitate HCV entry, at least in part, by regulating the association of CD81 with tetraspanin-enriched microdomains.