Integrin alpha 8 beta 1 promotes attachment, cell spreading, and neurite outgrowth on fibronectin.
The integrin alpha 8 subunit, isolated by low stringency hybridization, is a novel integrin subunit that associates with beta 1. To identify ligands, we have prepared a function-blocking antiserum to the extracellular domain of alpha 8, and we have established by transfection K562 cell lines that stably express alpha 8 beta 1 heterodimers on the cell surface. We demonstrate here by cell adhesion and neurite outgrowth assays that alpha 8 beta 1 is a fibronectin receptor. Studies on fibronectin fragments using RGD peptides as inhibitors show that alpha 8 beta 1 binds to the RGD site of fibronectin. In contrast to the endogenous alpha 5 beta 1 fibronectin receptor in K562 cells, alpha 8 beta 1 not only promotes cell attachment but also extensive cell spreading, suggesting functional differences between the two receptors. In chick embryo fibroblasts, alpha 8 beta 1 is localized to focal adhesions. We conclude that alpha 8 beta 1 is a receptor for fibronectin and can promote attachment, cell spreading, and neurite outgrowth on fibronectin.
Müller
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U
Department of Physiology, University of California at San Francisco 94143-0724, USA.
Bossy
B
B
Venstrom
K
K
Reichardt
L F
LF
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D002448:Cell Adhesion; D002454:Cell Differentiation; D002642:Chick Embryo; D005353:Fibronectins / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D016023:Integrins / Q000502:physiology*; D008024:Ligands; D016501:Neurites / Q000502:physiology*; D009842:Oligopeptides / Q000276:immunology / Q000494:pharmacology*; D017469:Receptors, Fibronectin / Q000276:immunology*; D011971:Receptors, Immunologic; D014407:Tumor Cells, Cultured
D000906:Antibodies; D005353:Fibronectins; D016023:Integrins; D008024:Ligands; D009842:Oligopeptides; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; C094866:integrin alpha8beta1; C047981:arginyl-glycyl-aspartic acid