Sodium taurocholate cotransporting polypeptide (NTCP) is expressed at the surface of human hepatocytes and functions as an entry 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 entry 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 entry 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 4β (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.

中文翻译：

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表皮生长因子受体的内吞作用机制协调了传入的乙型肝炎病毒向内体网络的运输。

牛磺胆酸钠共转运多肽（NTCP）在人肝细胞表面表达，并作为乙型肝炎病毒（HBV）的进入受体。最近，我们已经报道了表皮生长因子受体（EGFR）在细胞进入过程中参与了NTCP介导的病毒内在化。在这里，我们分析了EGFR的哪些功能对于介导HBV内在化至关重要。与报道的EGFR下游信号转导对于丙型肝炎病毒（HCV）进入至关重要的功能相反，EGFR下游信号转导蛋白的阻断，包括促分裂原活化蛋白激酶（MAPK），磷酸肌醇3激酶（PI3K）和信号转导子和转录激活子（STAT）对HBV感染没有影响或影响很小。反而，EGFR的有害突变或内吞作用衔接子分子的基因敲低导致EGFR内吞作用缺乏，从而消除了通过NTCP导致的HBV内在化，并防止了病毒感染。EGFR激活与EGFR转运协同作用，导致HBV preS1在时间上依赖于重新定位到早期和晚期内体和溶酶体。通过定点诱变或敲低两个EGFR分选分子，信号转导衔接子分子（STAM）和溶酶体蛋白跨膜4β（LAPTM4B）抑制EGFR泛素化，表明EGFR转运至晚期内体对于有效感染HBV至关重要。累积地，这些结果支持了EGFR内吞/分选机制驱动NTCP结合的HBV从细胞表面向内体网络转运的想法，