Krüppel-like factor 4 is induced by rapamycin and mediates the anti-proliferative effect of rapamycin in rat carotid arteries after balloon injury.
OBJECTIVE
The transcription factor, Krüppel-like factor 4 (KLF4), plays an important role in regulating the proliferation of vascular smooth muscle cells. This study aimed to examine the effect of rapamycin on the expression of KLF4 and the role of KLF4 in arterial neointimal formation.


METHODS
Expression of KLF4 was monitored using real-time PCR and immunoblotting in cultured vascular smooth muscle cells. and in rat carotid arteries in vivo after balloon injury. Adenovirus-mediated overexpression and siRNA-mediated knockdown of KLF4 were used to examine the role of KLF4 in mediating the anti-proliferative role of rapamycin . KLF4-regulated genes were identified using cDNA microarray.


RESULTS
Rapamycin induced the expression of KLF4 in vitro and in vivo. Overexpression of KLF4 inhibited cell proliferation and the activity of mammalian target of rapamycin (mTOR) and its downstream pathways, including 4EBP-1 and p70S6K in vascular smooth muscle cells and prevented the neointimal formation in the balloon-injured arteries. KLF4 up-regulated the expression of GADD45β, p57(kip2) and p27(kip1) . Furthermore, knockdown of KLF4 attenuated the anti-proliferative effect of rapamycin both in vitro and in vivo.


CONCLUSIONS
KLF4 plays an important role in mediating the anti-proliferative effect of rapamycin in VSMCs and balloon-injured arteries. Thus, it is a potential target for the treatment of proliferative vascular disorders such as restenosis after angioplasty.
Peking University Health Science Center, Beijing, China.
Ying
Y
Wang
Beilei
B
Zhao
Yi
Y
Zhang
Zhihui
Z
Tang
Qiang
Q
Shen
Youyi
Y
Zhang
Weizhen
W
Zhang
Jie
J
Du
Shu
S
Chien
Nanping
N
Wang
D000800:Angioplasty, Balloon / Q000009:adverse effects; D000818:Animals; D001483:Base Sequence; D020212:Carotid Artery Injuries / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics; D055785:Gene Knockdown Techniques; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects; D058426:Neointima / Q000473:pathology / Q000517:prevention & control; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors
C000715469:Klf4 protein, rat; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D034741:RNA, Small Interfering; D050760:Cyclin-Dependent Kinase Inhibitor p27; C546845:mTOR protein, rat; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus