Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P17931 (galectin-3)
 2,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transmembrane mucins are highly O-glycosylated glycoproteins that coat the apical glycocalyx on mucosal surfaces and represent the first line of cellular defense against infection and injury. Relatively low levels of N-glycans are found on transmembrane mucins, and their structure and function remain poorly characterized. We previously reported that carbohydrate-dependent interactions of transmembrane mucins with galectin-3 contribute to maintenance of the epithelial barrier at the ocular surface. Now, using MALDI-TOF mass spectrometry, we report that transmembrane mucin N-glycans in differentiated human corneal epithelial cells contain primarily complex-type structures with N-acetyllactosamine, a preferred galectin ligand. In N-glycosylation inhibition experiments, we find that treatment with tunicamycin and siRNA-mediated knockdown of the Golgi N-acetylglucosaminyltransferase I gene (MGAT1) induce partial loss of both total and cell-surface levels of the largest mucin, MUC16, and a concomitant reduction in glycocalyx barrier function. Moreover, we identified a distinct role for N-glycans in promoting MUC16's binding affinity toward galectin-3 and in causing retention of the lectin on the epithelial cell surface. Taken together, these studies define a role for N-linked oligosaccharides in supporting the stability and function of transmembrane mucins on mucosal surfaces.
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PMID:N-Glycosylation affects the stability and barrier function of the MUC16 mucin. 2848 69