摘要：SummaryThe severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike glycoprotein (S) binds to angiotensin-converting enzyme 2 (ACE2) to mediate membrane fusion via two distinct pathways: 1) a surface, serine protease-dependent or 2) an endosomal, cysteine protease-dependent pathway. In this study, we found that SARS-CoV-2 S has a wider protease usage and can also be activated by TMPRSS13 and matrix metalloproteinases (MMPs). We found that MMP-2 and MMP-9 played roles in SARS-CoV-2 S cell-cell fusion and TMPRSS2- and cathepsin-independent viral entry in cells expressing high MMP levels. MMP-dependent viral entry required cleavage at the S1/S2 junction in viral producer cells, and differential processing of variants of concern S dictated its usage; the efficiently processed Delta S preferred metalloproteinase-dependent entry when available, and less processed Omicron S was unable to us metalloproteinases for entry. As MMP-2/9 are released during inflammation, they may play roles in S-mediated cytopathic effects, tropism, and disease outcome.Graphical abstractDisplay OmittedHighlights•MMP-2 and MMP-9 enable SARS-CoV-2 S-mediated syncytia in the absence of TMPRSS2•SARS-CoV-2 can enter cells via MMPs in a TMPRSS2- and cathepsin-independent manner•MMP-dependent S activation requires prior S1/S2 processing•Delta S can readily use MMPs for entry while Omicron S cannotBiological sciences; Molecular biology; Microbiology; Virology
