Lipid raft adhesion receptors and Syk regulate selectin-dependent rolling under flow conditions.
Selectins and their ligand P-selectin glycoprotein ligand-1 (PSGL-1) mediate leukocyte rolling along inflamed vessels. Cell rolling is modulated by selectin interactions with their ligands and by topographic requirements including L-selectin and PSGL-1 clustering on tips of leukocyte microvilli. Lipid rafts are cell membrane microdomains reported to function as signaling platforms. Here, we show that disruption of leukocyte lipid rafts with cholesterol chelating agents depleted raft-associated PSGL-1 and L-selectin and strongly reduced L-, P-, and E-selectin-dependent rolling. Cholesterol repletion reversed inhibition of cell rolling. Importantly, leukocyte rolling on P-selectin induced the recruitment of spleen tyrosine kinase (Syk), a tyrosine kinase associated to lipid raft PSGL-1. Furthermore, inhibition of Syk activity or expression, with pharmacologic inhibitors or by RNA interference, strongly reduced leukocyte rolling on P-selectin, but not on E-selectin or PSGL-1. These observations identify novel regulatory mechanisms of leukocyte rolling on selectins with a strong dependency on lipid raft integrity and Syk activity.
Abbal
Claire
C
Service of Hematology, CHUV, Lausanne, Switzerland.
Lambelet
Martine
M
Bertaggia
Debora
D
Gerbex
Carole
C
Martinez
Manuel
M
Arcaro
Alexandre
A
Schapira
Marc
M
Spertini
Olivier
O
D002784:Cholesterol / Q000502:physiology; D019040:E-Selectin; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D019041:L-Selectin; D036904:Leukocyte Rolling; D008562:Membrane Glycoproteins; D021962:Membrane Microdomains / Q000737:chemistry* / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology*; D009504:Neutrophils / Q000737:chemistry / Q000502:physiology*; D019007:P-Selectin; D019038:Platelet Glycoprotein GPIb-IX Complex; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D019087:Selectins; D013314:Stress, Mechanical; D000072377:Syk Kinase
D019040:E-Selectin; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D019007:P-Selectin; C084882:P-selectin ligand protein; D019038:Platelet Glycoprotein GPIb-IX Complex; D019087:Selectins; C094990:adhesion receptor; D019041:L-Selectin; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase