The αvβ3 Integrin Regulates α5β1-mediated Cell Migration toward Fibronectin*
- From the Departments of ‡Bone Biology and Osteoporosis and §Pharmacology, Merck Research Laboratories, West Point, Pennsylvania 19486
Abstract
This study examines the interactions of αvβ3 and α5β1 in the regulation of cell migration. Human embryonic kidney (HEK) 293 cells that express α5β1 endogenously were transfected with αvβ3 and β3 mutants, and their attachment and migration to fibronectin (Fn) and vitronectin (Vn) were measured. An αvβ3 blocking antibody and the αvβ3 ligand cyclic G-Pen-GRGDSPC-A inhibited α5β1-mediated migration toward Fn, but not attachment to Fn. This function was αvβ3-specific since αvβ5 transfection and αvβ5 blocking antibody did not produce this effect. Mutations introduced into the β3 integrin subunit to dissect this phenomenon revealed the following. Disruption of the ligand binding domain by the Glanzmann thrombasthenia mutation β3-D119Y constitutively abolished migration toward both Vn and Fn, and attachment to Vn but not to Fn. Insertion of the Glanzmann mutation β3-S752P into the cytoplasmic domain or its truncation (β3-Δ717) abolished binding to Vn but not to Fn. Inhibition of migration toward Fn was inhibited in these cells by αvβ3 blocking antibody. αvβ3-mediated inhibition was, however, abolished by truncation of the transmembrane domain (β3-Δ693). These findings demonstrate αvβ3 regulation of α5β1-mediated cell migration and suggest that the β3 transmembrane domain is essential for this function.
Footnotes
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↵* The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed. Fax: 215-652-4328.
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↵1 The abbreviations used are: Fn, fibronectin; Col I, collagen type I; Col IV, collagen type IV; FnR, fibronectin receptor; HUVEC, human umbilical vein endothelial cell; Ln, laminin; Vn, vitronectin; VnR, vitronectin receptor; IAP, integrin-associated protein; mAb, monoclonal antibody; FBS, fetal bovine serum; FITC, fluorescein isothiocyanate; uPAR, urokinase-type plasminogen activator receptor; MEM, minimal essential medium.
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- Received April 15, 1997.
- Revision received July 1, 1997.
