Cytoskeletal rearrangement in K562 erythroleukaemic cells forced to grow on a positively charged polymer surface

We have recently demonstrated that if human K562 erythroleukaemic cells, wh ich normally grow in suspension, are grown on a positively-charged surface composed of polylysine, a transient reorganization of CD54 (ICAM-1), CD58 ( LFA-3) and alpha nu beta(3) (vitronecin receptor), three important CAMs loc ated on the cell membrane, takes place. In addition, changes of longer dura tion in membrane conductivity (ionic transport across the cell membrane) an d membrane permittivity (static distribution of charges across the cell mem brane), indicating more permanent structural as well as functional alterati ons in the cell membrane, were also observed [2]. Because of the close inte rrelationship which exists between the cell membrane, CAMs and the cytoskel eton, changes in this intracellular network as well as in the surface morph ology of K562 cells grown on the positively-charged polymer, polylysine, we re examined. In particular, actin and tubulin were investigated qualitative ly and quantitatively by immunofluorescence microscopy and flow cytometry, respectively, while the cell surface was studied by scanning electron micro scopy (SEM). The data indicate that when K562 cells are grown onto polylysi ne no quantitative changes occurred to the cytoskeletal elements even if th ese were rearranged and that the cell membrane surface is also greatly alte red. These results are discussed in light of the pivotal role played by CAM s and the cell cytoskeleton in transducing environmental stimuli, in this c ase those provided by a positive charge, from the cell membrane to the insi de of the cell. (C) 1999 Kluwer Academic Publishers.