Angiotensin Blockade Inhibits Activation of Mitogen-Activated Protein Kinases in Rat Balloon-Injured Artery

Abstract

Background-The effect of balloon injury on the arterial signal transduction pathway has not been examined. In vitro studies show that extracellular signal-regulated kinases (ERKs) and c-Jun NH 2 -terminal kinases (JNKs), belonging to the mitogen-activated protein kinase (MAPK) family, play a critical role in the activation of transcription factor activator protein-1 (AP-1) and cell proliferation or apoptosis. However, the activation and role of MAPKs in vascular diseases in vivo remain to be determined. Therefore, we examined the effect of balloon injury on arterial MAPKs and the possible role of angiotensin II. Methods and Results-Arterial JNK and ERK activities were measured by in-gel kinase assay. AP-1 DNA binding activity was determined by gel mobility shift analysis. After balloon injury of rat carotid artery, JNK (p46JNK and p55JNK) and ERK (p44ERK and p42ERK) activities were increased as early as 2 minutes, reached their peak (6-to 18-fold) at 5 minutes, and thereafter rapidly declined to control levels. JNK and ERK activations were followed by a 3.9-fold increase in arterial AP-1 DNA binding activity, which contained c-Jun and c-Fos proteins. Arterial JNK activation at 2 or 5 minutes was remarkably suppressed by E4177 (an angiotensin AT1 receptor antagonist) and cilazapril (an ACE inhibitor). E4177 also prevented activation of ERKs by suppressing their tyrosine phosphorylation, whereas cilazapril failed to prevent such activation. The increased AP-1 DNA binding activity was significantly inhibited by both E4177 and cilazapril. Conclusions-Arterial JNKs and ERKs are dramatically activated by balloon injury associated with the activation of the AP-1 complex. These MAPK activations, followed by AP-1 activation, are mediated at least in part by the AT1 receptor. Thus, activation of JNKs and ERKs may be responsible for balloon injury-induced neointima formation. (Circulation. 1998;97:1731-1737.)

Dominant negative c-Jun gene transfer inhibits vascular smooth muscle cell proliferation and neointimal hyperplasia in rats

“…16 However, the biological role of AP-1 in vascular SMC remains to be determined. We and other groups of investigators have previously reported that AP-1-binding activity, composed of c-Jun, is significantly enhanced in injured rat artery by balloon angioplasty, the elevation of blood pressure, or angiotensin II infusion, [11][12][13][14] suggesting that AP-1 containing c-Jun may play some role in various vascular diseases. These findings encouraged us to examine the role of AP-1 in vascular SMC proliferation and intimal hyperplasia in injured artery, by gene transfer of dominant negative mutant of c-Jun.…”

“…9,10 Recently, AP-1 has been reported to be rapidly activated in balloon-injured artery and this activated AP-1 contained c-Jun, 11 and similar findings have been also obtained by our recent work. 12 Furthermore, in rats, vascular AP-1, composed of c-Jun, is also significantly activated in vivo by acute hypertension or angiotensin II administration. 13,14 However, the significance of AP-1 for vascular diseases remains to be defined, mainly because of the lack of the specific and potent pharmacological inhibitor of AP-1.…”

“…12 SMCs were harvested by scraping with lysis buffer, sonicated, centrifuged to obtain the supernatant, and stored at Ϫ80°C until use. Antibodies against c-Jun (sc-44; Santa Cruz, Santa Cruz, CA, USA) (1:10 000) were used for the detection of DN-c-Jun protein.…”

“…At 2 days after gene transfer, the endothelial denudation of the left common carotid artery was carried out by three passages of a Fogarty 2F balloon catheter (Baxter Healthcare, Deerfield, IL, USA) through the left femoral artery, as previously described. 12,28 Measurement of ratio of intimal/medial areas For the estimation of ratio of intimal/medial areas (I/M ratio), at 14 days after balloon injury, rats were anesthetized with ether, and carotid arteries were fixed by perfusion of 10% (wt/vol) formaldehyde for 15 min under constant pressure, removed, embedded in paraffin and sectioned at 3 m thickness. Cross-sections were stained with Elastica Van Gieson, and hematoxylin and eosin.…”

Dominant-negative mutant of c-Jun gene transfer: a novel therapeutic strategy for colorectal cancer

“…31 Ex vivo tissue samples were immediately frozen at À801C after dissection. Frozen tissue was homogenized by thawing the samples in an appropriate volume of the lysis buffer, followed by disruption with a polytron homogenizer.…”