Journal Article

Glycosylated extracellular mucin domains protect against SARS-CoV-2 infection at the respiratory surface

van Putten, Jos P. M., Westendorp, Bart, Lamers, Mart M., Huang, Liane Z. X., Chatterjee, Maitrayee, Mykytyn, Anna Z., Wubbolts, Richard W., Haagmans, Bart L., Bosch, Berend-Jan, Wang, Chunyan, Strijbis, Karin

2023

Overview

Mucins play an essential role in protecting the respiratory tract against microbial infections while also acting as binding sites for bacterial and viral adhesins. The heavily O -glycosylated gel-forming mucins MUC5AC and MUC5B eliminate pathogens by mucociliary clearance. Transmembrane mucins MUC1, MUC4, and MUC16 can restrict microbial invasion at the apical surface of the epithelium. In this study, we determined the impact of host mucins and mucin glycans on epithelial entry of SARS-CoV-2. Human lung epithelial Calu-3 cells express the SARS-CoV-2 entry receptor ACE2 and high levels of glycosylated MUC1, but not MUC4 and MUC16, on their cell surface. The O -glycan-specific mucinase StcE specifically removed the glycosylated part of the MUC1 extracellular domain while leaving the underlying SEA domain and cytoplasmic tail intact. StcE treatment of Calu-3 cells significantly enhanced infection with SARS-CoV-2 pseudovirus and authentic virus, while removal of terminal mucin glycans sialic acid and fucose from the epithelial surface did not impact viral entry. In Calu-3 cells, the transmembrane mucin MUC1 and ACE2 are located to the apical surface in close proximity and StcE treatment results in enhanced binding of purified spike protein. Both MUC1 and MUC16 are expressed on the surface of human organoid-derived air-liquid interface (ALI) differentiated airway cultures and StcE treatment led to mucin removal and increased levels of SARS-CoV-2 replication. In these cultures, MUC1 was highly expressed in non-ciliated cells while MUC16 was enriched in goblet cells. In conclusion, the glycosylated extracellular domains of different transmembrane mucins might have similar protective functions in different respiratory cell types by restricting SARS-CoV-2 binding and entry.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: ACE2 / Acids / Adhesins / Analysis / Angiotensin-converting enzyme 2 / Antibodies / Binding sites / Biology and Life Sciences / Cell surface / Cells / Composition / COVID-19 / Datasets / Enzymes / Epithelium / Glycan / Glycoproteins / Goblet cells / Health aspects / Infection / Infections / Localization / Medicine and health sciences / Microorganisms / Microscopy / Molecular weight / Mucin / Mucinase / Mucins / Organic acids / Organoids / Pathogens / Physical Sciences / Polysaccharides / Protection and preservation / Protein binding / Proteins / Research and Analysis Methods / Respiratory tract / Severe acute respiratory syndrome coronavirus 2 / Spike protein / Viral diseases / Viral infections / Viruses