Myosin II-actin interaction in MDCK cells: role in cell shape changes in response to Ca2+ variations.

摘要: Cultured MDCK cell monolayers respond to a low level of extracellular calcium ([Ca2+]e≤5μm) with loss transepithelial electrical resistance and transport function, changes in position circumferential ring actin filaments tethered the plasma membrane at zonula adhaerens. Keeping this cytoskeletal structure place seems necessary preserve architecture tight junctions therefore their sealing capacity. All three effects are reversible upon restituting normal [Ca2+]e. Recent work provided evidence actin–myosin interactions filament ring, thus suggesting contraction process involved alteration cytoskeleton. We now report that active does occur causes an extensive morphological transformation cells. A marked increase height simultaneous decrease width area contact substratum was seen within 10min removal [Ca2+]e; recovery began immediately after replacing calcium, although it took longer for completion. Conventional confocal epifluorescence studies showed colocalized myosin II various planes resting or contracted cells, particular level. Electron-micrographs revealed associated waist-like constriction when Ca2+ removed from cultures. Contraction, as well relaxation, response [Ca2+]e variations were inhibited by cytochalasin-D (an actin-filament disrupting drug), okadaic acid inhibitor light-chain dephosphorylation), 2,3-butanedione monoxime (a blocker ATPase activity). Similarly, no observed cells previously depleted metabolic energy 2,4-dinitrophenol 2-deoxy-D-glucose preincubation. The mediated structural poses new questions interpretation vitro experiments, understanding epithelial function.