title: Hypotonic stress influence the membrane potential and alter the proliferation of keratinocytes in vitro.
abstract: Keratinocyte proliferation and differentiation is strongly influenced by mechanical forces. We investigated the effect of osmotic changes in the development of HaCaT cells in culture using intracellular calcium measurements, electrophysiological recordings and molecular biology techniques. The application of hypotonic stress (174 mOsmol/l) caused a sustained hyperpolarization of HaCaT cells from a resting potential of -27 +/- 4 to -51 +/- 9 mV. This change was partially reversible. The surface membrane channels involved in the hyperpolarization were identified as chloride channels due to the lack of response in the absence of the anion. Cells responded with an elevation of intracellular calcium concentration to hypotonic stress, which critically depended on external calcium. The presence of phorbol-12-myristate-13-acetate in the culture medium for 12 h augmented the subsequent response to hypotonic stress. A sudden switch from iso- to hypotonic solution increased cell proliferation and suppressed the production of involucrin, filaggrin and transglutaminase, markers of keratinocyte differentiation. It is concluded that sudden mechanical forces increase the proliferation of keratinocytes through alterations in their membrane potential and intracellular calcium concentration. These changes together with additional modifications in channel expression and intracellular signalling mechanisms could underlie the increased proliferation of keratinocytes in hyperproliferative skin diseases.
authors.affiliation: Department of Physiology, University of Debrecen, Debrecen, Hungary.
authors.forename: Mónika
authors.initials: M
authors.lastname: Gönczi
authors.forename: Norbert
authors.initials: N
authors.lastname: Szentandrássy
authors.forename: László
authors.initials: L
authors.lastname: Fülöp
authors.forename: Andrea
authors.initials: A
authors.lastname: Telek
authors.forename: Gyula P
authors.initials: GP
authors.lastname: Szigeti
authors.forename: János
authors.initials: J
authors.lastname: Magyar
authors.forename: Tamás
authors.initials: T
authors.lastname: Bíró
authors.forename: Péter P
authors.initials: PP
authors.lastname: Nánási
authors.forename: László
authors.initials: L
authors.lastname: Csernoch
mesh_terms: D001798:Blood Proteins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002461:Cell Line, Transformed; D002712:Chlorides / Q000494:pharmacology; D000091344:Filaggrin Proteins; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology*; D066298:In Vitro Techniques; D015603:Keratinocytes / Q000166:cytology* / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D013314:Stress, Mechanical; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
chemical_list: D001798:Blood Proteins; D002712:Chlorides; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007038:Hypotonic Solutions; D002118:Calcium