title: Ca(2+)- and calcineurin-dependent recycling of an integrin to the front of migrating neutrophils.
abstract: Chemoattractants stimulate neutrophil migration by activating signalling pathways including repeated transient increases in intracellular free calcium, [Ca2+]i. A motile neutrophil sends out many pseudopods, some of which adhere to the substrate; to continue moving forward the cell must release these attachments. Adhesion can be actively regulated, and neutrophils in which [Ca2+]i transients are inhibited become stuck on fibronectin or vitronectin, extracellular matrix proteins that neutrophils encounter in vivo. Function-blocking antibodies to beta 3 integrins or the alpha v beta 3 heterodimer restore motility on vitronectin to [Ca2+]i-buffered cells (B. Hendey, M.A.L., E. Marcantonio and F.R.M., manuscript submitted), indicating that an alpha v beta 3-like integrin is responsible for the [Ca2+]i-sensitive adhesion. We show that the density of alpha v beta 3 integrins in the adherent membrane of neutrophils migrating on vitronectin is much higher at the leading edge than at the rear, but [Ca2+]i buffering or inhibition of Ca(2+)-calmodulin-activated protein phosphatase 2B (calcineurin) leads to accumulation of alpha v beta 3 on the adherent surface at the rear of the cell. We show that the polarized distribution of alpha v beta 3 integrins in migrating neutrophils is maintained by [Ca2+]i-dependent release of adhesion followed by endocytosis of these integrins and recycling to the leading edge.
authors.affiliation: Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Lawson
authors.forename: F R
authors.initials: FR
authors.lastname: Maxfield
mesh_terms: D019703:Calcineurin; D002118:Calcium / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D004705:Endocytosis; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D016023:Integrins / Q000378:metabolism*; D018613:Microscopy, Confocal; D009504:Neutrophils / Q000378:metabolism* / Q000648:ultrastructure; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011554:Pseudopodia / Q000378:metabolism; D019030:Receptors, Vitronectin; D016608:Talin / Q000378:metabolism; D019096:Vitronectin
chemical_list: D002148:Calmodulin-Binding Proteins; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D016023:Integrins; D019030:Receptors, Vitronectin; D016608:Talin; D019096:Vitronectin; C064660:integrin alphaVbeta5; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D002118:Calcium