Blood, 1 July 2001, Vol. 98, No. 1, pp. 108-116
HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY
Platelet/polymorphonuclear leukocyte adhesion: a new role for SRC
kinases in Mac-1 adhesive function triggered by P-selectin
Paola Piccardoni,
Rita Sideri,
Stefano Manarini,
Antonio Piccoli,
Nicola Martelli,
Giovanni de
Gaetano,
Chiara Cerletti, and
Virgilio Evangelista
From the Department of Vascular Medicine and
Pharmacology, "G.Bizzozero" Laboratory of Blood and Vascular Cell
Interactions, Istituto di Ricerche Farmacologiche Mario Negri,
Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy; and
Università Cattolica del Sacro Cuore, Centro di Ricerca e
Formazione ad Alta Tecnologia nelle Scienze Biomediche, Campobasso,
Italy.
Adhesion of polymorphonuclear leukocytes (PMNLs) to
activated platelets requires a P-selectin-triggered, tyrosine
kinase-dependent adhesiveness of Mac-1 and is accompanied by tyrosine
phosphorylation of a 110-kd protein (P-110) in PMNLs.
Inhibitors of SRC tyrosine kinases were found to inhibit PMNL adhesion
to activated platelets or to P-selectin expressing Chinese hamster
ovary (CHO-P) cells and the tyrosine phosphorylation of P-110. Adhesion
of PMNLs to activated platelets or to CHO-P cells stimulated activity
of LYN and HCK. Monoclonal antibody blockade of P-selectin or
2-integrins reduced the activation of both kinases. In PMNLs either
adherent to platelets or aggregated by P-selectin-IgG chimera, Mac-1
was rapidly redistributed to the Triton X-100-insoluble cytoskeletal fraction, and large clusters of Mac-1 colocalized with patches of
F-actin at the sites of cell-cell contact. In PMNLs stimulated by
P-selectin-IgG chimera, SRC kinase inhibition impaired Mac-1 clustering, F-actin accumulation, and CD18 redistribution to the cytoskeleton. Disruption of the actin filament network by cytochalasin D prevented PMNL-platelet adhesion and P-selectin-induced PMNL aggregation and impaired the clustering of Mac-1. In agreement with the
requirement for the 2-integrin in the functional up-regulation of
LYN and HCK, integrin blockade by monoclonal antibodies resulted in a
complete inhibition of P-selectin-induced Mac-1 clustering and F-actin
accumulation. Taken together, the results indicate that, after an
initial P-selectin-triggered 2-integrin interaction with the
ligand, SRC kinases are activated and allow the remodeling of
cytoskeleton-integrin linkages and integrin clustering that finally
strengthen cell-cell adhesion. This model highlights a new role for SRC
kinases in a regulatory loop by which the Mac-1 promotes its own
adhesive function.
