Muc1 mucins on the cell surface are adhesion sites forPseudomonas aeruginosa

Abstract

Recently, we cloned and characterized a full-length cDNA of the hamster Muc1 gene, the expression of which appears to be associated with secretory cell differentiation (Park HR, Hyun SW, and Kim KC. Am J Respir Cell Mol Biol 15: 237-244, 1996). The role of Muc1 mucins in the airway, however, is unknown. In this study, we investigated whether cell surface mucins are adhesion sites for Pseudomonas aeruginosa. Chinese hamster ovary (CHO) cells not normally expressing Muc1 mucin were stably transfected with the hamster Muc1 cDNA, and binding to P. aeruginosa was examined. Our results showed that 1) stably transfected CHO cells expressed both Muc1 mRNA and Muc1 mucins based on Northern and Western blot analyses, 2) Muc1 mucins present on the cell surface were degraded by neutrophil elastase, and 3) expression of Muc1 mucins on the cell surface resulted in a significant increase in adhesion of P. aeruginosa that was completely abolished by either proteolytic cleavage with neutrophil elastase or deletion of the extracellular domain by mutation. We conclude that Muc1 mucins expressed on the surface of CHO cells serve as adhesion sites for P. aeruginosa, suggesting a possible role for these glycoproteins in the early stage of airway infection and providing a model system for studying epithelial cell responses to bacterial adhesion that leads to airway inflammation in general and cystic fibrosis in particular.

The cell surface mucin MUC1 limits the severity of influenza A virus infection

“…Such chemoattraction and adherence to specific mucin carbohydrates have also been demonstrated for mouse adenovirus type I (MAVS-1) 40 and respiratory syncytial virus (RSV), 13 as well as bacteria including Campylobacter jejuni, 24 Helicobacter pylori 26 and Pseudomonas aeruginosa. 25 In this study we have been able to block IAV infection of MDCK cells with synthetic MUC1 glycopeptides expressing a2-6-linked Neu5Ac, with those having a longer peptide chain of 20 amino acids being much more efficient than glycopeptides of 11 amino acids in length. This difference may reflect steric hindrance of receptor-binding sites on adjacent monomers of the trimeric HA molecule.…”

“…Initially, the large extracellular domain, which is heavily O-glycosylated with oligosaccharide structures terminating in Neu5Ac, acts as a virus trap and a releasable decoy ligand for IAV, resulting in partial dampening of infection during the early stages. Second, we contend that, as observed for other pathogens, [24][25][26] MUC1 regulates influenza virus-induced inflammation that would otherwise contribute to more severe pulmonary disease and potentially death. Understanding the MUC1 regulatory mechanisms in the context of IAV infection is of obvious interest to our future studies and may lead to an understanding of the mechanism as to why IAV infection is as a major trigger for disease exacerbations in patients with chronic respiratory illnesses where cs-mucins are aberrantly expressed.…”

“…As many microbial pathogens are known to trigger shedding of the MUC1 extracellular domain (ED) after binding, [24][25][26][27] we tested whether this phenomenon could also be caused by IAV. Supernatants were collected from PR8-infected CHO-K1 control and MUC1 þ cell cultures and the amount of MUC1-ED present in the supernatant was determined by ELISA.…”

NEU1 Sialidase Expressed in Human Airway Epithelia Regulates Epidermal Growth Factor Receptor (EGFR) and MUC1 Protein Signaling

“…ϭ 100) and incubated for 24 h. The cells were washed twice with PBS, fixed for 10 min with 2.5% glutaraldehyde in PBS at room temperature, and washed three times with PBS as described (30). Green fluorescent protein-expressing Pseudomonas aeruginosa strain PA01 (GFP-PA01) provided by Dr. Joanna B. Goldberg (University of Virginia, Charlottesville, VA) (31) was cultured overnight in LB broth, washed twice with PBS, resuspended in PBS containing 2.0 mg/ml glucose, and quantified spectrophotometrically at A 600 .…”

Regulation of Airway Mucin Gene Expression

“…It is expressed in secretory epithelial cells of the airways, GI tract, and female reproductive tract and is associated with goblet cells (124). Its function is not well defined yet, but it appears to play a role in antiadhesion of tumor cells or bacteria (124,125). It can mediate signal transduction responses through Ras, β-catenin, and p53.…”