Environmental Health Perspectives 105, Supplement 5, September 1997: Article by Barchowsky et al.

Environmental Health Perspectives 105, Supplement 5, September 1997

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Increased Focal Adhesion Kinase- and Urokinase-type Plasminogen Activator Receptor-associated Cell Signaling in Endothelial Cells Exposed to Asbestos

A. Barchowsky, B.M. Lannon, L.C. Elmore, and M.D. Treadwell

Department of Pharmacology, Dartmouth Medical School, Hanover, New Hampshire

Abstract
Exposure of low-passage endothelial cells in culture to nonlethal amounts of asbestos, but not refractory ceramic fiber-1, increases cell motility and gene expression. These changes may be initiated by the fibers mimicking matrix proteins as ligands for receptors on the cell surface. In the present study, 1- to 3-hr exposures of endothelial cells to 5 mg/cm ² of chrysotile asbestos caused marked cell elongation and motility. However, little morphological change was seen when chrysotile was added to cells pretreated with either mannosamine to prevent assembly of glycophosphatidylinositol (GPI)-anchored receptors or with herbimycin A to inhibit tyrosine kinase activity. Affinity purification of GPI-anchored urokinase-type plasminogen activator receptor (uPAR) from chrysotile-exposed cells demonstrated that asbestos altered the profile of proteins and phosphoproteins complexed with this receptor. Tyrosine kinase activities in the complexes were also increased by asbestos. Immunoprecipitations with selective monoclonal antibodies demonstrated that both chrysotile and crocidolite asbestos increase kinase activities associated with p60 Src or p120 focal adhesion kinase (FAK). Further, chrysotile also changed the profile of proteins and phosphoproteins associated with FAK in intact cells. These data suggest that asbestos initiates endothelial cell phenotypic change through interactions with uPAR-containing complexes and that this change is mediated through tyrosine kinase cascades.-- Environ Health Perspect 105(Suppl 5):1131-1137 (1997)

Key words : focal adhesion kinase, endothelial, urokinase-type plasminogen activator receptor, asbestos, Src kinase

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1997; accepted 31 March 1997.

This work was supported by the following grants from the National Institutes of Health: HL52738 (AB), ES07373 (AB), and OH03267 (MDT).

Address correspondence to Dr. A. Barchowsky, Department of Pharmacology, Dartmouth Medical School, 7650 Remsen, Hanover, NH 03755. Telephone: (603) 650-1673. Fax: (603) 650-1129. E-mail: barchowsky@dartmouth.edu

Abbreviations used: BSA, bovine serum albumin; DMEM, Dulbecco's modified Eagle's medium; FAK, focal adhesion kinase; FBS, fetal bovine serum; GPI, glycophosphatidylinositol; PAGE, polyacrylamide gel electrophoresis; PBS, phosphate-buffered saline; RCF, refractory ceramic fiber; uPA, urokinase-type plasminogen activator; uPAR, uPA receptor.

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Last Update: October 17, 1997