Cytoskeletal interactions regulate inducible L-selectin clustering.
L-selectin (CD62L) amplifies neutrophil capture within the microvasculature at sites of inflammation. Activation by G protein-coupled stimuli or through ligation of L-selectin promotes clustering of L-selectin and serves to increase its adhesiveness, signaling, and colocalization with beta(2)-integrins. Currently, little is known about the molecular process regulating the lateral mobility of L-selectin. On neutrophil stimulation, a progressive change takes place in the organization of its plasma membrane, resulting in membrane domains that are characteristically enriched in glycosyl phosphatidylinositol (GPI)-anchored proteins and exclude the transmembrane protein CD45. Clustering of L-selectin, facilitated by E-selectin engagement or antibody cross-linking, resulted in its colocalization with GPI-anchored CD55, but not with CD45 or CD11c. Disrupting microfilaments in neutrophils or removing a conserved cationic motif in the cytoplasmic domain of L-selectin increased its mobility and membrane domain localization in the plasma membrane. In addition, the conserved element was critical for L-selectin-dependent tethering under shear flow. Our data indicate that L-selectin's lateral mobility is regulated by interactions with the actin cytoskeleton that in turn fortifies leukocyte tethering. We hypothesize that both membrane mobility and stabilization augment L-selectin's effector functions and are regulated by dynamic associations with membrane domains and the actin cytoskeleton.
Mattila
Polly E
PE
Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108, USA.
Green
Chad E
CE
Schaff
Ulrich
U
Simon
Scott I
SI
Walcheck
Bruce
B
D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D019040:E-Selectin / Q000378:metabolism; D006801:Humans; D019041:L-Selectin / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D019040:E-Selectin; D019041:L-Selectin