title: Ultrastructural study of echinocytes induced by poly (ethylene glycol)-cholesterol.
abstract: Poly (ethylene glycol)-cholesterol (PEG-Chol) consists of a hydrophilic PEG and hydrophobic cholesterol moiety. When PEG-Chol was applied to erythrocytes, the reagent quantitatively induced protrusions by exclusively distributing in the outer monolayer of the membrane. This kind of response has been regarded as a general response that reduces the stress of expansion of the outer monolayer. However, the relationship between the membrane architecture and the distribution of such molecules is unknown. In this study, we examined the distribution of tagged PEG-Chol along the shape change pathway. The echinocytic shape was initiated by the initial formation of bumps on the rim of the discoid, which subsequently elongated as protrusions. These protrusions contained aggregates of granular structures, which appeared to accommodate the increase in the outer monolayer area. At higher concentrations, PEG-Chol further induced sphero-echinocytosis that resulted in numerous branched protrusion processes. We found that PEG-Chol was exclusively distributed in these protrusions and, in particular, accumulated at the tips. These results suggested that externally intercalated PEG-Chol was sequestrated from erythrocytes as membrane protrusions through an as-yet-unknown mechanism.
authors.affiliation: Department of Anatomy, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Tamaho, 409-3898 Yamanashi, Japan. tbaba@yamanashi.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Baba
authors.forename: Nobuo
authors.initials: N
authors.lastname: Terada
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Fujii
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Ohno
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ohno
authors.forename: Satoshi B
authors.initials: SB
authors.lastname: Sato
mesh_terms: D022081:Cell Surface Extensions / Q000187:drug effects* / Q000648:ultrastructure; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects* / Q000648:ultrastructure*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D016253:Microscopy, Immunoelectron; D011092:Polyethylene Glycols / Q000494:pharmacology*
chemical_list: C095164:poly(oxyethylene) cholesteryl ether; D011092:Polyethylene Glycols; D002784:Cholesterol