Transformation of chicken embryo fibroblasts by v-src uncouples beta 1 integrin-mediated outside-in but not inside-out signaling

Citation
A. Datta et al., Transformation of chicken embryo fibroblasts by v-src uncouples beta 1 integrin-mediated outside-in but not inside-out signaling, MOL CELL B, 21(21), 2001, pp. 7295-7306
Citations number
69
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Molecular Biology & Genetics
Journal title
MOLECULAR AND CELLULAR BIOLOGY
ISSN journal
0270-7306 → ACNP
Volume
21
Issue
21
Year of publication
2001
Pages
7295 - 7306
Database
ISI
SICI code
0270-7306(200111)21:21<7295:TOCEFB>2.0.ZU;2-0
Abstract
Adhesion of cells to extracellular matrix is mediated by integrin family re ceptors. The process of receptor-ligand binding is dependent on metabolic e nergy and is regulated by intracellular signals, termed inside-out signals. The strength of the initial alpha5 beta1-mediated adhesion of v-src-transf ormed chicken embryo fibroblasts (v-srcCEF) was similar to that of normal C EF. A chemically cross-linked fibronectin substrate was able to restore cel l spreading and the ability of v-srcCEF to assemble a fibronectin matrix. O ver time, v-srcCEF showed decreased adhesion due to the reduction of alpha5 beta1-fibronectin bonds consequent on the reduction of substrate-bound fib ronectin due to the secretion of proteases by v-srcCEF. Excess synthesis of hyaluronic acid by v-srcCEF also reduced the alpha5 beta1-fibronectin bond s and contributed to cell detachment at later times in culture. Thus, the a dhesion defects were not due to a failure of alpha5 beta1 function and adhe sion of the v-srcCEF was alpha5 beta1 dependent. Integrin-mediated adhesion also produces signals that affect cell proliferation and cell differentiat ion. An early consequence of these "outside-in" signals was the phosphoryla tion of FAK Y397 in direct proportion to the number of alpha5 beta1-fibrone ctin bonds formed. In contrast, v-srcCEF had an increased level of phosphor ylation on five different tyrosines in FAK, and none of these phosphorylati on levels were sensitive to the number of alpha5 beta1-fibronectin bonds. I n the absence of serum, CEF proliferation was sensitive to changes in alpha 5 beta1-mediated adhesion levels. Transformation by v-src increased the ser um-free proliferation rate and made it insensitive to alpha5 beta1-mediated adhesion. Thus, the v-srcCEF were insensitive to the normal outside-in sig nals from alpha5 beta1 integrin.