Macropinocytosis and SARS-CoV-2 cell entry

Macropinocytosis is a type of large-scale endocytosis that is triggered by the interaction of receptor proteins and ligands, such as growth factors, cytokines, chemokines, and lipopolysaccharide (LPS). Macropinocytosis ingests the extracellular fluid solutes and conveys them into the lysosome in the context of cell growth and differentiation. Aside from its physiological functions, macropinocytosis has been observed in viral infections. While the infectious mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still unknown, recent studies suggest the involvement of macropinocytosis in its cell entry. In this review, we discuss the roles of endocytosis in SARS-CoV/SARS-CoV-2 cell entries and propose a hypothetical role of macropinocytosis in SARS-CoV-2 cell entry.