This Article Full Text Full Text (PDF) All Versions of this Article: 22/11/1899    most recent 01.ATV.0000036080.42391.33v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tsukamoto, K. Articles by Matsuzawa, Y. Search for Related Content PubMed PubMed Citation Articles by Tsukamoto, K. Articles by Matsuzawa, Y. Related Collections Lipids Cell biology/structural biology Other arteriosclerosis Lipid and lipoprotein metabolism

(Arteriosclerosis, Thrombosis, and Vascular Biology. 2002;22:1899.)
© 2002 American Heart Association, Inc.

Atherosclerosis and Lipoproteins

Retarded Intracellular Lipid Transport Associated With Reduced Expression of Cdc42, a Member of Rho-GTPases, in Human Aged Skin Fibroblasts

A Possible Function of Cdc42 in Mediating Intracellular Lipid Transport

Kosuke Tsukamoto; Ken-ichi Hirano; Shizuya Yamashita; Naohiko Sakai; Chiaki Ikegami; Zhongyan Zhang; Fumihiko Matsuura; Hisatoyo Hiraoka; Akifumi Matsuyama; Masato Ishigami; Yuji Matsuzawa

From the Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, Osaka, Japan.

Correspondence to Ken-ichi Hirano, MD, PhD, Department of Internal Medicine and Molecular Science, Graduate School of Medicine, B5, Osaka University, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail khirano{at}kb3.so-net.ne.jp

Objective— Many cell types in atherosclerotic lesions are thought to have various biological abnormalities, such as impaired lipid homeostasis and slow cell proliferation, which may be related to senescence at cellular and individual levels. One of the common characteristics of senescent cells in vitro is the alteration of actin cytoskeletons, which have been reported to be involved in the intracellular transport of lipids. Recently, we raised the hypothesis that Cdc42, which is a member of the Rho-GTPase family and is known to play an important role in actin dynamics, might be important in cellular lipid transport.

Methods and Results— In the present study, we found that the protein expression levels and GTP-binding activities of Cdc42 were decreased in aged human skin fibroblasts. Moreover, we found the intracellular kinetics of Golgi-associated lipids to be retarded in these cells, which was demonstrated by the fluorescence recovery after photobleaching (FRAP) technique and the use of N-[7-(4-nitrobenzo-2-oxa-1,3-diazole)]-6-aminohexanoyl-D-erythro-sphingosine as a tracer. To correlate the decreased expression of Cdc42 with the retarded FRAP, we complemented the amount of wild-type c-myc–tagged Cdc42Hs (myc-Cdc42Hs-WT) by adenovirus-mediated gene transfer. We further tested the effect of the dominant-active form (myc-Cdc42Hs-DA, V12Cdc42Hs) or dominant-negative form (myc-Cdc42Hs-DN, N17Cdc42Hs) of Cdc42Hs on FRAP. Introduction of myc-Cdc42Hs-WT or myc-Cdc42Hs-DA recovered the retarded FRAP in the aged fibroblasts. Conversely, control fibroblasts infected with myc-Cdc42Hs-DN exhibited significantly retarded FRAP.

Conclusions— These data clearly indicate that the expression of Cdc42, a small G protein, is decreased in the aged cells in close association with the retarded intracellular lipid transport. The present study demonstrates a possible function of Cdc42 in the mediation of intracellular lipid transport.

Key Words: aging • Cdc42 • fluorescence recovery after photobleaching • intracellular lipid transport • vesicular transport

This article has been cited by other articles:

				J.-R. Nofer, A. T. Remaley, R. Feuerborn, I. Wolinnska, T. Engel, A. von Eckardstein, and G. Assmann Apolipoprotein A-I activates Cdc42 signaling through the ABCA1 transporter J. Lipid Res., April 1, 2006; 47(4): 794 - 803. [Abstract] [Full Text] [PDF]

				S. M. Bared, C. Buechler, A. Boettcher, R. Dayoub, A. Sigruener, M. Grandl, C. Rudolph, A. Dada, and G. Schmitz Association of ABCA1 with Syntaxin 13 and Flotillin-1 and Enhanced Phagocytosis in Tangier Cells Mol. Biol. Cell, December 1, 2004; 15(12): 5399 - 5407. [Abstract] [Full Text] [PDF]

				J.-R. Nofer, R. Feuerborn, B. Levkau, A. Sokoll, U. Seedorf, and G. Assmann Involvement of Cdc42 Signaling in ApoA-I-induced Cholesterol Efflux J. Biol. Chem., December 26, 2003; 278(52): 53055 - 53062. [Abstract] [Full Text] [PDF]