Danying Liao1,2, Jesse Sundlov1, Jieqing Zhu1,3, Heng Mei2, Yu Hu2, Debra K Newman1,4,5,6, Peter J Newman1,2,4,7,6. 1. Blood Research Institute, Versiti Blood Center of Wisconsin, Milwaukee (D.L., J.S., J.Z., D.K.N., P.J.N.). 2. Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, China (D.L., H.M., Y.H., P.J.N.). 3. Department of Biochemistry (J.Z.), Medical College of Wisconsin, Milwaukee. 4. Department of Pharmacology (D.K.N., P.J.N.), Medical College of Wisconsin, Milwaukee. 5. Department of Microbiology (D.K.N.), Medical College of Wisconsin, Milwaukee. 6. The Cardiovascular Center (D.K.N., P.J.N.), Medical College of Wisconsin, Milwaukee. 7. Department of Cell Biology, Neurobiology and Anatomy (P.J.N.), Medical College of Wisconsin, Milwaukee.
Abstract
OBJECTIVE: PECAM-1 (platelet endothelial cell adhesion molecule 1) is a 130 kDa member of the immunoglobulin (Ig) gene superfamily that is expressed on the surfaces of platelets and leukocytes and concentrated at the intercellular junctions of confluent endothelial cell monolayers. PECAM-1 Ig domains 1 and 2 (IgD1 and IgD2) engage in homophilic interactions that support a host of vascular functions, including support of leukocyte transendothelial migration and the maintenance of endothelial junctional integrity. The recently solved crystal structure of PECAM-1 IgD1 and IgD2 revealed a number of intermolecular interfaces predicted to play important roles in stabilizing PECAM-1/PECAM-1 homophilic interactions and in formation and maintenance of endothelial cell-cell contacts. We sought to determine whether the protein interfaces implicated in the crystal structure reflect physiologically important interactions. Approach and Results: We assessed the impact of single amino acid substitutions at the interfaces between opposing PECAM-1 molecules on homophilic binding and endothelial cell function. Substitution of key residues within the IgD1-IgD1 and IgD1-IgD2 interfaces but not those within the smaller IgD2-IgD2 interface, markedly disrupted PECAM-1 homophilic binding and its downstream effector functions, including the ability of PECAM-1 to localize at endothelial cell-cell borders, mediate the formation of endothelial tubes, and restore endothelial barrier integrity. CONCLUSIONS: Taken together, these results validate the recently described PECAM-1 IgD1/IgD2 crystal structure by demonstrating that specific residues visualized within the IgD1-IgD1 and IgD1-IgD2 interfaces of opposing molecules in the crystal are required for functionally important homophilic interactions. This information can now be exploited to modulate functions of PECAM-1 in vivo.
OBJECTIVE: PECAM-1 (platelet endothelial cell adhesion molecule 1) is a 130 kDa member of the immunoglobulin (Ig) gene superfamily that is expressed on the surfaces of platelets and leukocytes and concentrated at the intercellular junctions of confluent endothelial cell monolayers. PECAM-1 Ig domains 1 and 2 (IgD1 and IgD2) engage in homophilic interactions that support a host of vascular functions, including support of leukocyte transendothelial migration and the maintenance of endothelial junctional integrity. The recently solved crystal structure of PECAM-1 IgD1 and IgD2 revealed a number of intermolecular interfaces predicted to play important roles in stabilizing PECAM-1/PECAM-1 homophilic interactions and in formation and maintenance of endothelial cell-cell contacts. We sought to determine whether the protein interfaces implicated in the crystal structure reflect physiologically important interactions. Approach and Results: We assessed the impact of single amino acid substitutions at the interfaces between opposing PECAM-1 molecules on homophilic binding and endothelial cell function. Substitution of key residues within the IgD1-IgD1 and IgD1-IgD2 interfaces but not those within the smaller IgD2-IgD2 interface, markedly disrupted PECAM-1 homophilic binding and its downstream effector functions, including the ability of PECAM-1 to localize at endothelial cell-cell borders, mediate the formation of endothelial tubes, and restore endothelial barrier integrity. CONCLUSIONS: Taken together, these results validate the recently described PECAM-1 IgD1/IgD2 crystal structure by demonstrating that specific residues visualized within the IgD1-IgD1 and IgD1-IgD2 interfaces of opposing molecules in the crystal are required for functionally important homophilic interactions. This information can now be exploited to modulate functions of PECAM-1 in vivo.
Authors: Jamie R Privratsky; Cathy M Paddock; Oliver Florey; Debra K Newman; William A Muller; Peter J Newman Journal: J Cell Sci Date: 2011-04-12 Impact factor: 5.285
Authors: Sibylle von Vietinghoff; Gisela Tunnemann; Claudia Eulenberg; Maren Wellner; M Cristina Cardoso; Friedrich C Luft; Ralph Kettritz Journal: Blood Date: 2007-01-23 Impact factor: 22.113
Authors: Ulrich J H Sachs; Cornelia L Andrei-Selmer; Amudhan Maniar; Timo Weiss; Cathy Paddock; Valeria V Orlova; Eun Young Choi; Peter J Newman; Klaus T Preissner; Triantafyllos Chavakis; Sentot Santoso Journal: J Biol Chem Date: 2007-06-19 Impact factor: 5.157