Visualization of sialyl Lewis(X) glycosphingolipid microdomains in model membranes as selectin recognition motifs using a fluorescence label.
Selectin-induced leukocyte rolling along the endothelial surface is an essential step in the cellular immune response. For efficient recognition, the relevant carbohydrate epitope sialyl Lewis(X) (sLe(X); alpha-Neup5Ac-(2-->3)-beta-Galp-(1-->4)-[alpha-Fucp-(1-->3)]GlcpNAc) has to be arranged in clusters. We describe the synthesis of the sLe(X)-glycosphingolipid (sLe(X)-GSL) with a NBD fluorescence label in the tail region, which allows the direct visualization of sLe(X)-GSL microdomains to very low concentrations (0.01mol%) in various planar phosphocholine matrices by fluorescence microscopy. Cell rolling experiments of E-selectin expressing cells along these membranes confirmed that the fluorescence analog behaves similar to the naturally occuring sLe(X)-GSL. This is direct evidence for recent hypotheses on multivalent sLe(X) binding as molecular basis for selectin-mediated cell rolling.
Gege
Christian
C
Department of Chemistry, Universität Konstanz, Box M725, D-78457 Konstanz, Germany. christian.gege@web.de
Schumacher
Gabriele
G
Rothe
Ulrich
U
Schmidt
Richard R
RR
Bendas
Gerd
G
D000818:Animals; D016466:CHO Cells; D002240:Carbohydrate Sequence; D006224:Cricetinae; D003412:Cricetulus; D019040:E-Selectin / Q000378:metabolism*; D006028:Glycosphingolipids / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D000080506:Sialyl Lewis X Antigen
D019040:E-Selectin; D006028:Glycosphingolipids; D008051:Lipid Bilayers; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen