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

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

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

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 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.

Original languageEnglish
Article numbere1011571
JournalPLoS Pathogens
Volume19
Issue number8 August
DOIs
Publication statusPublished - 10 Aug 2023

Bibliographical note

Funding Information:
Funding: MC is supported by One Health funding provided by the Faculty of Veterinary Medicine. KS and LZXH are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation program (ERC-2019-STG-852452). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Publisher Copyright:
Copyright: © 2023 Chatterjee et al.

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