title: Changes in Na(+)-K(+)-ATPase activity influence cell attachment to fibronectin.
abstract: Most vital cellular functions are dependent on a fine-tuned regulation of intracellular ion homeostasis. Here we have demonstrated, using COS cells that were untransfected or transfected with wild-type rat ouabain-resistant Na(+)-K(+)-ATPase, that partial inhibition of Na(+)-K(+)-ATPase has a dramatic influence on cell attachment to fibronectin. Ouabain dose-dependently decreased attachment in untransfected cells and in cells expressing wild-type Na(+)-K(+)-ATPase, but not in cells expressing ouabain-insensitive Na(+)-K(+)-ATPase, whereas inhibition of Na(+)-K(+)-ATPase by lowering extracellular K(+) concentration decreased attachment in all three cell types. Thirty percent inhibition of Na(+)-K(+)-ATPase significantly attenuated attachment. Na(+)-K(+)-ATPase inhibition caused a sustained increase in the intracellular Ca(2+) concentration that obscured Ca(2+) transients observed in untreated cells during attachment. Inhibitors of Ca(2+) transporters significantly decreased attachment, but inhibition of Na(+)/H(+) exchanger did not. Ouabain reduced focal adhesion kinase autophosphorylation but had no effect on cell surface integrin expression. These results suggest that the level of Na(+)-K(+)-ATPase activity strongly influences cell attachment, possibly by an effect on intracellular Ca(2+).
authors.affiliation: Department of Woman and Child Health, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Roger
authors.initials: R
authors.lastname: Belusa
authors.forename: Oleg
authors.initials: O
authors.lastname: Aizman
authors.forename: Ronnie M
authors.initials: RM
authors.lastname: Andersson
authors.forename: Anita
authors.initials: A
authors.lastname: Aperia
mesh_terms: D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002468:Cell Physiological Phenomena; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005353:Fibronectins / Q000502:physiology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007425:Intracellular Membranes / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011188:Potassium / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D005353:Fibronectins; D010042:Ouabain; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium