title: Actin-rich spherical extrusion induced in okadaic acid-treated K562 cells by crosslinking of membrane microdomains.
abstract: Interconnection between surface microdomains and the actin cytoskeleton is vital to various cellular activities. We studied the responses of okadaic acid (OKA)-treated K562 leukemia cells to crosslinking of membrane microdomains. Although OKA alone induced clustering of surface-bound F-actin, addition of a biotinylated poly(ethylene glycol) derivative of cholesterol (bPEG-Chol) and subsequent binding of streptavidin (SA) further induced accumulation of the clusters, resulting in the formation of a spherical cell extrusion. This extrusion was also induced by direct crosslinking of a raft marker, CD59, and ganglioside GM1. In addition, we found that knockout of the gene encoding Fyn kinase inhibited formation of the spherical extrusion in murine T-cells. In bPEG-Chol/SA-treated cells, CD59, ganglioside GM1, and clathrin/AP-2 were all accumulated on the surface of the actin-rich extrusion, whereas dynamin and transferrin receptors were unaffected. Intermediate filaments, mitochondria, and other vesicles also accumulated. These results suggest that crosslinking of membrane domains exaggerates the linkage between actin and a defined set of membrane proteins in OKA-treated cells.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Yamanashi, Japan. tbaba@res.yamanashimed.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Baba
authors.forename: Keiko
authors.initials: K
authors.lastname: Udaka
authors.forename: Nobuo
authors.initials: N
authors.lastname: Terada
authors.forename: Hideho
authors.initials: H
authors.lastname: Ueda
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Fujii
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ohno
authors.forename: Satoshi B
authors.initials: SB
authors.lastname: Sato
mesh_terms: D000199:Actins / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002966:Clathrin / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry*; D006801:Humans; D020014:K562 Cells; D008055:Lipids / Q000737:chemistry; D019319:Okadaic Acid / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D000199:Actins; D002966:Clathrin; D003432:Cross-Linking Reagents; D008055:Lipids; D019319:Okadaic Acid