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J. Cell Biol.,
Volume 142, Number 3, August 10, 1998 859-871


* Department of Medicine and Department of Biochemistry and Molecular Biology, and W.K. Warren Medical Research
Institute, University of Oklahoma Health Sciences Center, and Cardiovascular Biology Research Program, Oklahoma Medical
Research Foundation, Oklahoma City, Oklahoma 73104; and Flowing leukocytes tether to and roll on
P-selectin, a receptor on endothelial cells that is rapidly
internalized in clathrin-coated pits. We asked whether
the association of P-selectin with clathrin-coated pits
contributes to its adhesive function. Under flow, rolling neutrophils accumulated efficiently on CHO cells expressing wild-type P-selectin or a P-selectin construct
with a substitution in the cytoplasmic domain that
caused even faster internalization than that of the wild-type protein. By contrast, far fewer rolling neutrophils
accumulated on CHO cells expressing P-selectin constructs with a deletion or a substitution in the cytoplasmic domain that impaired internalization. Neutrophils
rolled on the internalization-competent constructs with
greater adhesive strength, slower velocity, and more
uniform motion. Flowing neutrophils tethered equivalently to internalization-competent or internalization-defective P-selectin, but after tethering, they rolled further on internalization-competent P-selectin. Confocal
microscopy demonstrated colocalization of
Department of Cell Biology and Neuroanatomy, University of
Minnesota, Minneapolis, Minnesota 55455
-adaptin,
a component of clathrin-coated pits, with wild-type P-selectin, but not with P-selectin lacking the cytoplasmic domain. Treatment of CHO cells or endothelial
cells with hypertonic medium reversibly impaired the
clathrin-mediated internalization of P-selectin and its
ability to support neutrophil rolling. Interactions of the
cytoplasmic domain of P-selectin with clathrin-coated
pits provide a novel mechanism to enhance leukocyte
adhesion under flow.
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