The machinery for endocytosis of epidermal growth factor receptor coordinates the transport of incoming hepatitis B virus to the endosomal network [Microbiology] (Journal of Biological Chemistry)

Sodium taurocholate cotransporting polypeptide (NTCP) is expressed at the surface of human hepatocytes and functions as an item receptor of hepatitis B virus (HBV). Recently, we have reported that epidermal growth factor receptor (EGFR) is involved in NTCP-mediated viral internalization during the cell item process. Here, we analyzed which function of EGFR is essential for mediating HBV internalization. In contrast to the reported crucial function of EGFR-downstream signaling for the item of hepatitis C virus (HCV), blockade of EGFR-downstream signaling proteins, including mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), and signal transducer and activator of transcription (STAT), had no or only minor effects on HBV infection. Instead, deficiency of EGFR endocytosis resulting from either a deleterious mutation in EGFR or genetic knockdown of endocytosis adaptor molecules abrogated internalization of HBV via NTCP and prevented viral infection. EGFR activation triggered a time-dependent relocalization of HBV preS1 to the early and late endosomes and to lysosomes in concert with EGFR transport. Suppression of EGFR ubiquitination by site-directed mutagenesis or by knocking down two EGFR-sorting molecules, signal-transducing adaptor molecule (STAM) and lysosomal protein transmembrane 4? (LAPTM4B), suggested that EGFR transport to the late endosome is critical for efficient HBV infection. Cumulatively, these results support the idea that the EGFR endocytosis/sorting machinery drives the translocation of NTCP-bound HBV from the cell surface to the endosomal network, which eventually enables productive viral infection.