Mutagenesis of the ezrin-radixin-moesin binding domain of L-selectin tail affects shedding, microvillar positioning, and leukocyte tethering.
L-selectin is a cell adhesion molecule that mediates the initial capture (tethering) and subsequent rolling of leukocytes along ligands expressed on endothelial cells. We have previously identified ezrin and moesin as novel binding partners of the 17-amino acid L-selectin tail, but the biological role of this interaction is not known. Here we identify two basic amino acid residues within the L-selectin tail that are required for binding to ezrin-radixinmoesin (ERM) proteins: arginine 357 and lysine 362. L-selectin mutants defective for ERM binding show reduced localization to microvilli and decreased phorbol 12-myristate 13-acetate-induced shedding of the L-selectin ectodomain. Cells expressing these L-selectin mutants have reduced tethering to the L-selectin ligand P-selectin glycoprotein ligand-1, but rolling velocity on P-selectin glycoprotein ligand-1 is not affected. These results suggest that ERM proteins are required for microvillar positioning of L-selectin and that this is important both for leukocyte tethering and L-selectin shedding.
Ivetic
Aleksandar
A
Ludwig Institute for Cancer Research, Royal Free and University College School of Medicine, 91 Riding House Street, London W1W 7BS United Kingdom. aleks@ludwig.ucl.ac.uk
Florey
Oliver
O
Deka
Jürgen
J
Haskard
Dorian O
DO
Ager
Ann
A
Ridley
Anne J
AJ
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine; D001665:Binding Sites; D001798:Blood Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006801:Humans; D007163:Immunosorbent Techniques; D019041:L-Selectin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism* / Q000648:ultrastructure; D008239:Lysine; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D008871:Microvilli / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010750:Phosphoproteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D013329:Structure-Activity Relationship; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D000099149:Ezrin
D001120:Arginine; D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D019041:L-Selectin; D008239:Lysine; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D013755:Tetradecanoylphorbol Acetate; D000099149:Ezrin; C084882:P-selectin ligand protein; C071058:moesin; C071776:radixin