title: Differential regulation of thyroid cell-cell and cell-substrate adhesion by thyrotropin.
abstract: Preservation of cell aggregation is necessary for thyroid follicular differentiation in vitro and requires stimulation by thyrotropin (TSH). We have tested the hypothesis that TSH preferentially increases thyroid cell-cell adhesion relative to cell-substrate adhesion. Cell-cell adhesion was measured in short-term suspension cultures by the decrease in the fraction of single cells remaining in culture (free cell ratio, FCR). When incubated in medium alone freshly isolated cells showed a progressive fall in FCR but this was accelerated by TSH and the cyclic AMP analog, 8-(4-chlorophenylthio)cyclic AMP. Aggregation was dependent upon extracellular Ca2+ and also promoted by a cell-free membrane extract. In contrast, attachment of cells to plastic dishes treated for tissue culture was not affected by TSH. We conclude that thyroid cells possess a TSH-sensitive cell adhesion system. The preferential increase in cell-cell adhesion may be one mechanism by which TSH stimulates the formation and preservation of follicles in vitro.
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: K C
authors.initials: KC
authors.lastname: Abel
authors.forename: J R
authors.initials: JR
authors.lastname: Bourke
authors.forename: S W
authors.initials: SW
authors.lastname: Manley
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D007700:Kinetics; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology*; D013972:Thyrotropin / Q000502:physiology*
chemical_list: D013972:Thyrotropin; D002118:Calcium