title: The Role of Sialylated Glycans in Human Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1)-mediated Trans Homophilic Interactions and Endothelial Cell Barrier Function.
abstract: Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1) is a major component of the endothelial cell intercellular junction. Previous studies have shown that PECAM-1 homophilic interactions, mediated by amino-terminal immunoglobulin homology domain 1, contribute to maintenance of the vascular permeability barrier and to its re-establishment following inflammatory or thrombotic insult. PECAM-1 glycans account for ∼30% of its molecular mass, and the newly solved crystal structure of human PECAM-1 immunoglobulin homology domain 1 reveals that a glycan emanating from the asparagine residue at position 25 (Asn-25) is located within the trans homophilic-binding interface, suggesting a role for an Asn-25-associated glycan in PECAM-1 homophilic interactions. In support of this possibility, unbiased molecular docking studies revealed that negatively charged α2,3 sialic acid moieties bind tightly to a groove within the PECAM-1 homophilic interface in an orientation that favors the formation of an electrostatic bridge with positively charged Lys-89, mutation of which has been shown previously to disrupt PECAM-1-mediated homophilic binding. To verify the contribution of the Asn-25 glycan to endothelial barrier function, we generated an N25Q mutant form of PECAM-1 that is not glycosylated at this position and examined its ability to contribute to vascular integrity in endothelial cell-like REN cells. Confocal microscopy showed that although N25Q PECAM-1 concentrates normally at cell-cell junctions, the ability of this mutant form of PECAM-1 to support re-establishment of a permeability barrier following disruption with thrombin was significantly compromised. Taken together, these data suggest that a sialic acid-containing glycan emanating from Asn-25 reinforces dynamic endothelial cell-cell interactions by stabilizing the PECAM-1 homophilic binding interface.
authors: From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.|the Departments of Pharmacology.
authors: Panida
authors: P
authors: Lertkiatmongkol
authors: From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.
authors: Cathy
authors: C
authors: Paddock
authors: From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.|the Departments of Pharmacology.
authors: Debra K
authors: DK
authors: Newman
authors: From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and.|Biochemistry, and.
authors: Jieqing
authors: J
authors: Zhu
authors: the Departments of Pharmacology.
authors: Michael J
authors: MJ
authors: Thomas
authors: From the Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, Wisconsin 53201, and peter.newman@bcw.edu.|the Departments of Pharmacology.|Cell Biology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors: Peter J
authors: PJ
authors: Newman
mesh_terms: D019943:Amino Acid Substitution; D002450:Cell Communication / Q000502:physiology*; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D020125:Mutation, Missense; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012794:Sialic Acids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013917:Thrombin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011134:Polysaccharides; D012794:Sialic Acids; D013917:Thrombin
keywords: adhesion; endothelial cell; glycosylation; permeability; platelet endothelial cell adhesion molecule (PECAM); sialic acid; vascular biology