Rad GTPase attenuates vascular lesion formation by inhibition of vascular smooth muscle cell migration.
BACKGROUND
Rad (Ras associated with diabetes) GTPase is a prototypic member of a new subfamily of Ras-related GTPases with unique structural features, although its physiological role remains largely unknown. In the present study, we characterized the Rad function in vascular smooth muscle cells (VSMCs) and the influence of adenovirus-mediated Rad (Ad-Rad) gene delivery on vascular remodeling after experimental angioplasty.


RESULTS
We documented for the first time that neointimal formation using balloon-injured rat carotid arteries was associated with a significant increase in Rad expression as determined by immunohistochemistry and quantitative real-time reverse-transcriptase polymerase chain reaction. The levels of Rad expression in VSMCs were highly induced by platelet-derived growth factor and tumor necrosis factor-alpha. Morphometric analyses 14 days after injury revealed significantly diminished neointimal formation in the Ad-Rad-treated carotid arteries compared with Ad-GFP or PBS controls, whereas the mutated form of Rad GTPase, which can bind GDP but not GTP, increased neointimal formation. Overexpression of Rad significantly inhibited the attachment and migration of VSMCs. In addition, Rad expression dramatically reduced the formation of focal contacts and stress fibers in VSMCs by blocking the Rho/ROK signaling pathway.


CONCLUSIONS
Our data clearly identified Rad GTPase as a novel and critical mediator that inhibits vascular lesion formation. Manipulation of the Rad signaling pathway may provide new therapeutic approaches that will limit vascular pathological remodeling.
Fu
Mingui
M
Cardiovascular Research Institute, Morehouse School of Medicine, Atlanta, Ga 30310, USA.
Zhang
Jifeng
J
Tseng
Yu-Hua
YH
Cui
Taixing
T
Zhu
Xiaojun
X
Xiao
Yan
Y
Mou
Yongshan
Y
De Leon
Hector
H
Chang
Mary M J
MM
Hamamori
Yasuo
Y
Kahn
C Ronald
CR
Chen
Yuqing E
YE
D000199:Actins / Q000037:antagonists & inhibitors; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000196:embryology; D002339:Carotid Arteries; D002465:Cell Movement / Q000502:physiology*; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D022502:Stress Fibers / Q000378:metabolism; D017539:Tunica Intima / Q000378:metabolism / Q000473:pathology; D018631:ras Proteins / Q000096:biosynthesis / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D054460:rho-Associated Kinases
D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; C084355:RRAD protein, human; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D018631:ras Proteins; D020741:rho GTP-Binding Proteins