Separate Oligosaccharide Determinants Mediate Interactions of the Low-Molecular-Weight Salivary Mucin with Neutrophils and Bacteria

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• 作者：Akraporn Prakobphol ; Kirsten Tangemann ; Steven D. Rosen ; Charles I. Hoover ; Hakon Leffler ; and Susan J. Fisher
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：May 25, 1999
• 年：1999
• 卷：38
• 期：21
• 页码：6817 - 6825
• 全文大小：89K
• 年卷期：v.38,no.21(May 25, 1999)
• ISSN：1520-4995

文摘

The low-molecular-weight human salivary mucin (MG2) coats oral surfaces, where it is in aprime location for governing cell adhesion. Since oligosaccharides form many of the interactive facets onmucin molecules, we examined MG2 glycosylation as it relates to the molecule's adhesive functions. Ourprevious study of MG2 oligosaccharide structures showed that the termini predominantly carry T, sialyl-T, Lewis^x (Le^x), sialyl Le^x (sLe^x), lactosamine, and sialyl lactosamine determinants [Prakobphol, A., etal. (1998) Biochemistry 37, 4916-4927]. In addition, we showed that sLe^x determinants confer L-selectinligand activity to this molecule. Here we studied adhesive interactions between MG2 and cells that trafficin the oral cavity: neutrophils and bacteria. Under flow conditions, neutrophils tethered to MG2-coatedsurfaces at forces between 1.25 and 2 dyn/cm², i.e., comparable to the shear stress generated at the toothsurface by salivary flow (~0.8 dyn/cm²). MG2 was also found in association with neutrophils isolatedfrom the oral cavity, evidence that the cells interact with this mucin in vivo. Since MG2 serves as anadhesion receptor for bacteria, the MG2 saccharides that serve this function were also identified. Sevenof 18 oral bacteria strains that were tested adhered to MG2. Importantly, six of these seven strains adheredvia T antigen, sialyl-T antigen, and/or lactosamine sequences. No adherence to Le^x and sLe^x epitopes wasdetected in all the strains that were tested. Together, these results suggest that distinct subsets of MG2saccharides function as ligands for neutrophil L-selectin and receptors for bacterial adhesion, a findingwith interesting implications for both oral health and mucin function.