Redox-Induced Src Kinase and Caveolin-1 Signaling in TGF-β1-Initiated SMAD2/3 Activation and PAI-1 Expression

Plasminogen activator inhibitor-1 (PAI-1), a major regulator of the plasmin-based pericellular proteolytic cascade, is significantly increased in human arterial plaques contributing to vessel fibrosis, arteriosclerosis and thrombosis, particularly in the context of elevated tissue TGF-β1. Identification of molecular events underlying to PAI-1 induction in response to TGF-β1 may yield novel targets for the therapy of cardiovascular disease.Reactive oxygen species are generated within 5 minutes after addition of TGF-β1 to quiescent vascular smooth muscle cells (VSMCs) resulting in pp60(c-src) activation and PAI-1 expression. TGF-β1-stimulated Src kinase signaling sustained the duration (but not the initiation) of SMAD3 phosphorylation in VSMC by reducing the levels of PPM1A, a recently identified C-terminal SMAD2/3 phosphatase, thereby maintaining SMAD2/3 in an active state with retention of PAI-1 transcription. The markedly increased PPM1A levels in triple Src kinase (c-Src, Yes, Fyn)-null fibroblasts are consistent with reductions in both SMAD3 phosphorylation and PAI-1 expression in response to TGF-β1 compared to wild-type cells. Activation of the Rho-ROCK pathway was mediated by Src kinases and required for PAI-1 induction in TGF-β1-stimulated VSMCs. Inhibition of Rho-ROCK signaling blocked the TGF-β1-mediated decrease in nuclear PPM1A content and effectively attenuated PAI-1 expression. TGF-β1-induced PAI-1 expression was undetectable in caveolin-1-null cells, correlating with the reduced Rho-GTP loading and SMAD2/3 phosphorylation evident in TGF-β1-treated caveolin-1-deficient cells relative to their wild-type counterparts. Src kinases, moreover, were critical upstream effectors of caveolin-1(Y14) phosphoryation and initiation of downstream signaling.TGF-β1-initiated Src-dependent caveolin-1(Y14) phosphorylation is a critical event in Rho-ROCK-mediated suppression of nuclear PPM1A levels maintaining, thereby, SMAD2/3-dependent transcription of the PAI-1 gene

Effects of endothelial dysfunction on residual platelet aggregability after dual antiplatelet therapy with aspirin and clopidogrel in patients with stable coronary artery disease

Background— Dual antiplatelet therapy with aspirin and clopidogrel is widely used in patients with coronary stents. High residual platelet reactivity (high RPR) after dual antiplatelet therapy is associated with increased cardiovascular events. Endothelial function could affect platelet reactivity in vivo. We hypothesized that endothelial dysfunction could be associated with high RPR after dual antiplatelet therapy in patients with stable coronary artery disease. Methods and Results— We screened patients with stable coronary artery disease for cytochrome P450 (CYP) 2C19 genotypes and enrolled 103 patients who lacked CYP2C19*2 or *3 loss-of-function allele to minimize the effect of this gene on high RPR. All patients received aspirin (100 mg/d) and clopidogrel (75 mg/d for long-term treatment or a loading dose of 300 mg) before the following tests. Platelet aggregability was assessed as P2Y12 reaction unit using the VerifyNow System. High RPR was defined as P2Y12 reaction unit ≥230. Peripheral endothelial function was expressed as reactive hyperemia index using reactive hyperemia peripheral arterial tonometry. Fifty-three patients exhibited high RPR. High RPR patients were significantly older, had higher levels of B-type natriuretic peptide, and were predominantly hypertensive compared with non–high RPR patients. Reactive hyperemia index was significantly lower in high RPR patients (0.46±0.15) compared with non–high RPR patients (0.61±0.18; P &lt;0.001). Linear regression analysis demonstrated significant negative correlation between reactive hyperemia index and P2Y12 reaction unit ( r =−0.32; P =0.001). Multivariable logistic regression analysis identified reactive hyperemia index as an independent and significant determinant of high RPR (odds ratio, 0.55; 95% confidence interval, 0.39–0.78; P =0.001). Conclusions— In patients with stable coronary artery disease, endothelial function was significantly impaired in high RPR patients. Endothelial dysfunction is independently correlated with high RPR after dual antiplatelet therapy. Clinical Trial Registration— URL: http://www.umin.ac.jp/ctr . Unique identifier: UMIN000008239. </jats:sec

Clinical characteristics and long-term prognosis of contemporary patients with vasospastic angina: Ethnic differences detected in an international comparative study.

BACKGROUND: Possible ethnic differences in clinical characteristics and long-term prognosis of contemporary patients with vasospastic angina (VSA) remain to be elucidated. METHODS AND RESULTS: The Japanese Coronary Spasm Association (JCSA) conducted an international, prospective, and multicenter registry study for VSA patients. A total of 1457 VSA patients (Japanese/Caucasians, 1339/118) were enrolled based on the same diagnostic criteria. Compared with Caucasian patients, Japanese patients were characterized by higher proportions of males (68 vs. 51%) and smoking history (60 vs. 49%). Japanese patients more often had angina especially during the night and early morning hours, compared with Caucasians. Ninety-five percent of Japanese and 84% of Caucasian patients underwent pharmacological provocation test. Importantly, no significant differences in the patterns of coronary spasm were apparent, with diffuse spasm most frequently noted in both ethnicities. The prescription rate of calcium-channel blockers was higher in Japanese (96 vs. 86%), whereas the uses of nitrates (46 vs. 59%), statins (43 vs. 65%), renin-angiotensin-system inhibitors (27 vs. 51%), and β-blockers (10 vs. 24%) were more common in Caucasian patients. Survival rate free from major adverse cardiac events (MACE) was slightly but significantly higher in Japanese than in Caucasians (86.7 vs. 76.6% at 5 years, P < 0.001). Notably, multivariable analysis revealed that the JCSA risk score correlated with MACE rates not only in Japanese but also in Caucasian patients. CONCLUSION: These results indicate that there are ethnic differences in clinical profiles and long-term prognosis of contemporary VSA patients

Sirt7 Deficiency Attenuates Neointimal Formation Following Vascular Injury by Modulating Vascular Smooth Muscle Cell Proliferation

Background: Sirt7 is a recently identified sirtuin and has important roles in various pathological conditions, including cancer progression and metabolic disorders. It has previously been reported that Sirt7 is a key molecule in acute myocardial wound healing and pressure overload-induced cardiac hypertrophy. In this study, the role of Sirt7 in neointimal formation after vascular injury is investigated. Methods and Results: Systemic (Sirt7(-/-)) and smooth muscle cell-specific Sirt7-deficient mice were subjected to femoral artery wire injury. Primary vascular smooth muscle cells (VSMCs) were isolated from the aorta of wild type (WT) and Sirt7(-/-) mice and their capacity for cell proliferation and migration was compared. Sirt7 expression was increased in vascular tissue at the sites of injury. Sirt7(-/-) mice demonstrated significant reduction in neointimal formation compared to WT mice. In vitro, Sirt7 deficiency attenuated the proliferation of serum-induced VSMCs. Serum stimulation-induced upregulation of cyclins and cyclin-dependent-kinase 2 (CDK2) was significantly attenuated in VSMCs of Sirt7(-/-) compared with WT mice. These changes were accompanied by enhanced expression of the microRNA 290-295 cluster, the translational negative regulator of CDK2, in VSMCs of Sirt7(-/-) mice. It was confirmed that smooth muscle cell-specific Sirt7-deficient mice showed significant reduction in neointima compared with control mice. Conclusions: Sirt7 deficiency attenuates neointimal formation after vascular injury. Given the predominant role in vascular neointimal formation, Sirt7 is a potentially suitable target for treatment of vascular diseases