title: Demonstration of contractility of circumferential actin bundles and its morphogenetic significance in pigmented epithelium in vitro and in vivo.
abstract: Each pigmented epithelial cell bears circumferential actin bundles at its apical level when the pigmented epithelium is established in eyes in situ or in culture in vitro. Well-differentiated pigmented epithelia in culture were treated with a 50% glycerol solution containing 0.1 M KCl, 5 mM EDTA, and 10 mM sodium phosphate buffer, pH 7.2, for 24 h or more at 4 degrees C. When the glycerinated epithelium was transferred to the ATP solution, each cell constituting the epithelium began to contract. The epithelium was cleaved into many cell groups as a result of contraction of each cell. The periphery of each cell group was lifted to form a cup or vesicle and eventually detached from the substratum. However, those cells that had not adhered tightly and not formed a monolayer epithelium with typical polygonal cellular pattern contracted independently as observed in the glycerinated fibroblasts. Contraction of the glycerinated pigmented epithelial cells was inhibited by N-ethylmaleimide but not by cytochalasin B. ITP and UTP also effected the contraction of the glycerinated cells, but GTP and ADP did not. Ca2+ was not required. This contractile model of pigmented epithelium provides a useful experimental system for analyzing the function of actin in cellular morphogenesis.
mesh_terms: D000199:Actins / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002642:Chick Embryo; D003571:Cytochalasin B / Q000494:pharmacology; D003599:Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D005033:Ethylmaleimide / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009024:Morphogenesis; D009711:Nucleotides / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000502:physiology
chemical_list: D000199:Actins; D009711:Nucleotides; D003571:Cytochalasin B; D008274:Magnesium; D005033:Ethylmaleimide; D002118:Calcium