title: Thyroid cell spreading and focal adhesion formation depend upon protein tyrosine phosphorylation and actin microfilaments.
abstract: Adhesion to proteins of the extracellular matrix exerts a profound influence upon cell function and behavior. Similar adhesive interactions mediate the spreading of cultured cells upon artificial substrata. Recently we observed that thyrotropin (TSH) and intercellular contact regulated thyroid cell-substrate adhesion to inhibit cell spreading, but not initial attachment. This is a mechanism which preserves thyroid follicular differentiation in culture. In the present study we have investigated the role of cytoplasmic components in mediating thyroid cell adhesion to collagen. The earliest change associated with cell spreading was the accumulation of vinculin and phosphotyrosine in developing focal adhesions, which was followed by stress fiber and microtubule assembly. Genistein, an inhibitor of tyrosine kinases, and cytochalasin B inhibited cell spreading and focal adhesion formation without affecting initial attachment to substrate. In contrast microtubule disorganization by colchicine did not alter any parameter of thyroid cell-substrate adhesion. These observations indicate that protein tyrosine phosphorylation and dynamic microfilament integrity are essential for attached thyroid cells to spread upon substrate. They are therefore potential intracellular loci at which TSH and intercellular contact may regulate cell adhesion to extracellular matrix and influence thyroid cell behavior.
authors.affiliation: Department of Physiology and Pharmacology, University of Queensland St. Lucia, Brisbane, Australia.
authors.forename: A S
authors.initials: AS
authors.lastname: Yap
authors.forename: J R
authors.initials: JR
authors.lastname: Keast
authors.forename: S W
authors.initials: SW
authors.lastname: Manley
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D019833:Genistein; D006493:Heparin / Q000494:pharmacology; D007529:Isoflavones / Q000494:pharmacology; D007700:Kinetics; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D016596:Vinculin / Q000032:analysis / Q000378:metabolism
chemical_list: D000199:Actins; D007529:Isoflavones; D016596:Vinculin; D019000:Phosphotyrosine; D003571:Cytochalasin B; D014443:Tyrosine; D006493:Heparin; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D003078:Colchicine