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Linkage to the actin cytoskeleton is critical for α4β1‐mediated leukocyte rolling and chemokine‐induced arrest, but not prolonged adhesion
Author(s) -
Rullo Jacob,
Hyduk Sharon J,
Digby Genevieve,
Lee Leslie,
Cybulsky Myron I
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.360.2
Subject(s) - microbiology and biotechnology , actin cytoskeleton , integrin , cytoskeleton , cell adhesion , adhesion , cell adhesion molecule , fluorescence recovery after photobleaching , chemistry , biology , receptor , biochemistry , cell , organic chemistry , membrane
The avidity or strength of integrin‐mediated cell adhesion is attributed to affinity (strength of individual bonds) and valency (number of bonds formed). We investigated the role of the actin cytoskeleton in α4β1 integrin mediated adhesion to VCAM‐1 in assays that model distinct steps of leukocyte emigration. In U937 cells stably transfected with the formyl peptide receptor, α4β1 integrin affinity up‐regulation induced by GPCR signaling remained intact following disruption of the actin cytoskeleton by cytochalasin D (cytoD) or latrunculin B (latB) (2 µM, 30 min incubation). Parallel plate flow chamber adhesion assays revealed that U937 cells pretreated with cytoD or latB failed to roll on surfaces coated with VCAM‐1 and arrest on surfaces co‐coated with VCAM‐1 and SDF‐1α. High affinity α4β1 induced by Mn2+ independent of GPCR signaling mediated spontaneous U937 arrest, which was blocked by cytoD or latB pretreatment. In contrast, U937 cell adhesion in 15 min assays was not inhibited by cytoD or latB. Fluorescence recovery after photobleaching demonstrated increased diffusion of α4β1 integrins in cells pretreated with cytoD, consistent with a disruption of integrin linkage to the actin cytoskeleton. These studies suggest that constitutive linkage of α4β1 integrins to the actin cytoskeleton is critical for mediating α4β1‐dependent rolling and arrest, but not prolonged leukocyte adhesion. Funded by CIHR.