Defective cholesterol efflux in Werner syndrome fibroblasts and its phenotypic correction by Cdc42, a RhoGTPase.
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.
Zhang
Zhongyan
Z
Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
Hirano
Ken-ichi
K
Tsukamoto
Kosuke
K
Ikegami
Chiaki
C
Koseki
Masahiro
M
Saijo
Kaoru
K
Ohno
Tadao
T
Sakai
Naohiko
N
Hiraoka
Hisatoyo
H
Shimomura
Iichiro
I
Yamashita
Shizuya
S
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
D002784:Cholesterol; D020764:cdc42 GTP-Binding Protein