title: Defective cholesterol efflux in Werner syndrome fibroblasts and its phenotypic correction by Cdc42, a RhoGTPase.
abstract: Werner syndrome (WS) is characterized by the early onset of senescent phenotypes including premature atherosclerotic cardiovascular diseases, although the underlying molecular mechanism for atherosclerosis has not been fully understood yet. Cholesterol efflux from the cells is the initial step of reverse cholesterol transport, a major protective system against atherosclerosis. The aim of the present study was to determine whether this crucial step may be altered in WS. We examined intracellular lipid transport and cholesterol efflux and the expression levels of its related molecules in skin fibroblasts obtained from patients with WS. Cholesterol efflux was markedly reduced in the WS fibroblasts in association with increased cellular cholesterol. Fluorescent recovery after photobleaching (FRAP) technique revealed that intracellular lipid transport around Golgi apparatus was markedly reduced when using a C6-NBD-Ceramide as a tracer. Cdc42 protein and its GTP-bound form were markedly reduced in the WS fibroblasts. The complementation of wild-type Cdc42 corrected cholesterol efflux, intracellular lipid transport, and cellular cholesterol levels in the WS fibroblasts. These data indicated that the reduced expression of Cdc42 may be responsible for the abnormal lipid transport, which in turn might be related to the cardiovascular manifestations in WS.
authors.affiliation: Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Hirano
authors.forename: Kosuke
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ikegami
authors.forename: Masahiro
authors.initials: M
authors.lastname: Koseki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Saijo
authors.forename: Tadao
authors.initials: T
authors.lastname: Ohno
authors.forename: Naohiko
authors.initials: N
authors.lastname: Sakai
authors.forename: Hisatoyo
authors.initials: H
authors.lastname: Hiraoka
authors.forename: Iichiro
authors.initials: I
authors.lastname: Shimomura
authors.forename: Shizuya
authors.initials: S
authors.lastname: Yamashita
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000328:Adult; D001161:Arteriosclerosis / Q000378:metabolism; D001692:Biological Transport; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D050356:Lipid Metabolism; D008875:Middle Aged; D014898:Werner Syndrome / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D002784:Cholesterol; D020764:cdc42 GTP-Binding Protein