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Title: Isolation and characterization of variants of polyoma transformed BHK 21 cells defective in adhesion to fibronectin
Author: Salama, Nasr M.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1986
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In order to investigate the interplay between the cell surface and the cytoskeleton in adhesion, variants of polyoma-transformed BHK 21 cells were isolated with or without N-methyl-N-nitro-N-nitrosoguanidine as a mutagen, which are of very low adhesiveness towards surfaces coated with fibronectin. On culture surface the variants yield loosely attached colonies of very distinctive unspread morphology. Variants retain the ability to cap fluorescent Con A, and are unable to spread on any surface yet tested, including adsorbed serum, Con A, fibronectin, vitronectin or poly-L-lysine. In a flow-chamber adhesion assay, which minimises the contribution of gross spreading to adhesion, the variants are much less adhesive to fibronectin or serum films than the parental cells, but they adhere equally to poly-L-lysine. A high proportion (35%) of cells in a variant population showed spreading ability on a clean tissue culture plastic surface. The proportion of variants spread is less than that of parental cells. Mn at 10-4M did not stimulate these variants to spread 'to full extent, but there was an increase in spreading in response to manganese on tissue culture plastic in absence of serum. An f-actin specific fluorescent probe showed the distribution of f-actin in Py3 cells on a surface coated with fibronectin. Stress fibres appeared very distinct. No stress fibres were observed in the variants in the course of study. f-actin was seen underneath the plasma membrane and at cell-cell contact areas. Proteins retained in detergent insoluble residues of Py3 and variants were studied by various techniques. No differences in protein bands were seen. The alteration in these variants can be explained as follows: 1. There are simultaneous changes in the ability of cell surface to bind fibronectin and in the cytoskeletal control. 2. The putative fibronectin receptor, altered in the variant, is involved in some way in the spreading response on all surfaces.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral