The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the COVID-19 global pandemic, utilizes the host receptor angiotensin-converting enzyme 2 (ACE2) for viral entry. However, other host factors might also play important roles in SARS-CoV-2 infection, providing new directions for antiviral treatments. GRP78 is a stress-inducible chaperone important for entry and infectivity for many viruses. Recent molecular docking analyses revealed putative interaction between GRP78 and the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein (SARS-2-S). Here we report that GRP78 can form a complex with SARS-2-S and ACE2 on the surface and at the perinuclear region typical of the endoplasmic reticulum in VeroE6-ACE2 cells and that the substrate-binding domain of GRP78 is critical for this interaction. In vitro binding studies further confirmed that GRP78 can directly bind to the RBD of SARS-2-S and ACE2. To investigate the role of GRP78 in this complex, we knocked down GRP78 in VeroE6-ACE2 cells. Loss of GRP78 markedly reduced cell surface ACE2 expression and led to activation of markers of the unfolded protein response. Treatment of lung epithelial cells with a humanized monoclonal antibody (hMAb159) selected for its safe clinical profile in preclinical models depleted cell surface GRP78 and reduced cell surface ACE2 expression, as well as SARS-2-S-driven viral entry and SARS-CoV-2 infection in vitro . Our data suggest that GRP78 is an important host auxiliary factor for SARS-CoV-2 entry and infection and a potential target to combat this novel pathogen and other viruses that utilize GRP78 in combination therapy.
【저자키워드】 SARS-CoV-2, ACE2, antibody, SARS-CoV-2, Severe acute respiratory syndrome coronavirus 2, ACE2, angiotensin-converting enzyme 2, RBD, receptor-binding domain, GRP78, Spike protein, GRP78, 78-kDa glucose-regulated protein, hMAb159, humanized monoclonal antibody, SARS-2-S, SARS-CoV-2-Spike protein, VeroE6-ACE2, VeroE6 cells overexpressing ACE2, 【초록키워드】 COVID-19, viruses, coronavirus, spike, SARS-COV-2 infection, Infection, molecular docking, combination therapy, virus, angiotensin-converting enzyme 2, viral entry, Endoplasmic reticulum, global pandemic, Protein, pathogen, cells, RBD, unfolded protein response, ACE2 expression, Critical, binding, marker, Interaction, Analysis, Safe, acute respiratory syndrome, Activation, Factor, host receptor, SARS-CoV-2 entry, complex, domain, SARS-2-S, chaperone, antiviral treatments, Host, humanized monoclonal antibody, Loss, recent, Cell, selected, reduced, the RBD, the receptor-binding domain, lung epithelial cell, auxiliary, knocked down, the SARS-CoV-2, 【제목키워드】 Infection, viral entry, chaperone, block, Host, depleting, auxiliary,