Cardiovascular Research Advance Access originally published online on June 7, 2008
Cardiovascular Research 2008 80(1):114-122; doi:10.1093/cvr/cvn158
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Rho-GDP dissociation inhibitor alpha downregulated by low shear stress promotes vascular smooth muscle cell migration and apoptosis: a proteomic analysis
1 Institute of Mechanobiology and Medical Engineering, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, PO Box 888, 800 Dongchuan Road, Minhang, Shanghai 200240, P.R. China
2 Departments of Bioengineering and Medicine, University of California, San Diego, La Jolla, CA 92093-0412, USA
* Corresponding author. Tel: +86 21 34204863; fax: +86 21 34204118. E-mail address: zljiang{at}sjtu.edu.cn
Aims: Low shear stress (LSS) plays a significant role in vascular remodelling during atherogenesis, which involves migration, proliferation, and apoptosis of vascular smooth muscle cells (VSMCs). The aim of the present study is to elucidate the molecular mechanisms by which LSS induces vascular remodelling.
Methods and results: Using proteomic techniques, two-dimensional electrophoresis, and mass spectrometry, the protein profiles of Sprague–Dawley rat aorta cultured under two levels of shear stress, 5 and 15 dyn/cm2, were determined. The results showed a significantly lower expression of protein-Rho-GDP dissociation inhibitor alpha (Rho-GDI
) in the LSS vessels. Rho-GDI
signalling mechanisms and effects on VSMC migration and apoptosis were then studied to understand the role of Rho-GDI
in the LSS-induced vascular remodelling. A decrease in Rho-GDI
expression by using target small interfering RNA (siRNA) transfection caused increases in the phosphorylation of Rac1 and Akt and enhancements of VSMC migration and apoptosis. Treatment with the PI3K/Akt-specific inhibitor wortmannin significantly decreased Akt phosphorylation, but had no effect on Rho-GDI
expression and Rac1 phosphorylation. Wortmannin was able to reverse the Rho-GDI
siRNA-induced enhancement of VSMC migration, but not VSMC apoptosis.
Conclusion: The results indicate that the LSS-induced VSMC migration and apoptosis are mediated by a downregulation of Rho-GDI
. The effect of Rho-GDI
on VSMC migration is mediated by the PI3K/Akt pathway, but its effect on VSMC apoptosis is not.
KEYWORDS Rho-GDI
; Migration; Apoptosis; Vascular smooth muscle cells; Shear stress
Time for primary review: 22 days