title: Neutrophil adhesion to E-selectin under shear promotes the redistribution and co-clustering of ADAM17 and its proteolytic substrate L-selectin.
abstract: E-selectin is expressed by the vascular endothelium and binds flowing neutrophils in the blood to facilitate their recruitment into the underlying tissue at sites of inflammation. L-selectin on neutrophils is engaged by E-selectin and undergoes rapid clustering and then coalescence in the trailing edge of polarizing cells. These processes are believed to increase the valency and capacity of L-selectin to signal CD18 integrin activity. Neutrophils, upon exiting the microvasculature, down-regulate their surface L-selectin through ectodomain shedding by a disintegrin and metalloprotease 17 (ADAM17). We reasoned that neutrophil tethering and rolling on E-selectin might initiate a coordinate change in the membrane distribution of ADAM17 as well. We found that ADAM17 indeed underwent a dramatic cell surface redistribution to the trailing edge of neutrophils rolling on purified E-selectin when activated by a chemoattractant under shear flow; however, its lateral migration occurred at a slower rate than L-selectin. ADAM17 and L-selectin also redistributed in the same manner in neutrophils attached to IL-1beta-stimulated HUVEC under shear flow. In contrast, the coalescence of L-selectin on the surface of neutrophils by antibody cross-linking did not promote the redistribution of ADAM17, suggesting that these molecules do not constitutively associate in the plasma membrane. Together, our findings reveal that neutrophil activation upon E-selectin adhesion initiates active transport of ADAM17 and L-selectin to the cell uropod, thus providing additional insight into the molecular mechanisms that regulate L-selectin during leukocyte extravasation.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schaff
authors.forename: Polly E
authors.initials: PE
authors.lastname: Mattila
authors.forename: Scott I
authors.initials: SI
authors.lastname: Simon
authors.forename: Bruce
authors.initials: B
authors.lastname: Walcheck
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism*; D000072198:ADAM17 Protein; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D019040:E-Selectin / Q000276:immunology* / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000276:immunology; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D019041:L-Selectin / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods; D009504:Neutrophils / Q000276:immunology*; D013314:Stress, Mechanical
chemical_list: D019040:E-Selectin; D053583:Interleukin-1beta; D019041:L-Selectin; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human