Accumulation of oxidized lipids in the arterial wall contributes to atherosclerosis. Glutathione peroxidase-4 (GPx4) is a hydroperoxide scavenger that removes oxidative modifications from lipids such as free fatty acids, cholesterols, and phospholipids. Here, we set out to assess the effects of GPx4 overexpression on atherosclerosis in apolipoprotein E-deficient (ApoE(-/-)) mice. The results revealed that atherosclerotic lesions in the aortic tree and aortic sinus of ApoE(-/-) mice overexpressing GPx4 (hGPx4Tg/ApoE(-/-)) were significantly smaller than those of ApoE(-/-) control mice. GPx4 overexpression also diminished signs of advanced lesions in the aortic sinus, as seen by a decreased occurrence of fibrous caps and acellular areas among hGPx4Tg/ApoE(-/-) animals. This delay of atherosclerosis in hGPx4Tg/ApoE(-/-) mice correlated with reduced aortic F(2)-isoprostane levels (R(2)=0.75, p<0.01). In addition, overexpression of GPx4 lessened atherogenic events induced by the oxidized lipids lysophosphatidylcholine and 7-ketocholesterol, including upregulated expression of adhesion molecules in endothelial cells and adhesion of monocytes to endothelial cells, as well as endothelial necrosis and apoptosis. These results suggest that overexpression of GPx4 inhibits the development of atherosclerosis by decreasing lipid peroxidation and inhibiting the sensitivity of vascular cells to oxidized lipids.

A reduction in endogenously generated reactive oxygen species in vivo delays benzo(α)pyrene (BaP)-accelerated atherosclerosis, as revealed in hypercholesterolemic mice overexpressing Cu/Znsuperoxide dismutase (SOD) and/or catalase. To understand the molecular events involved in this protective action, we studied the effects of Cu/Zn-SOD and/or catalase overexpression on BaP detoxification and on aryl hydrocarbon receptor (AhR) expression and its target gene expression in mouse aortic endothelial cells (MAECs). Our data demonstrate that overexpression of Cu/Zn-SOD and/or catalase leads to an 18-to 20-fold increase in the expression of AhR protein in MAECs. After BaP exposure, the amount of AhR binding to the cytochrome P450 (CYP) 1A1 promoter was significantly greater, and the concentrations of BaP reactive intermediates were significantly less in MAECs overexpressing Cu/Zn-SOD and/or catalase than in wild-type cells. In addition, the BaPinduced CYP1A1 and 1B1 protein levels and BaP-elevated glutathione S-transferase (GST) activity were significantly higher in these transgenic cells, in parallel with elevated GSTp1, CYP1A1, and CYP1B1 mRNA levels, compared to wild-type MAECs. Moreover, knockdown of AhR with RNA interference diminished the Cu/Zn-SOD and catalase enhancement of CYP1A1 expression, GST activity, and BaP detoxification. These data demonstrate that overexpression of Cu/Zn-SOD and/or catalase is associated with upregulation of AhR and its target genes, such as xenobiotic-metabolizing enzymes. KeywordsBenzo(α)pyrene; Aryl hydrocarbon receptor; Endothelial cells; Cu/Zn-superoxide dismutase; Catalase; Free radicals Polycyclic aromatic hydrocarbons (PAHs) are a class of chemical carcinogens found in cigarette smoke, automobile exhaust, and foods cooked at high temperature (reviewed in Refs. [17,33]). Benzo(α) pyrene (BaP), a representative PAH compound, has been shown to target vascular cells and accelerate the development of atherosclerosis [4]. A recent study from our laboratory demonstrated that over-expression of Cu/Zn-superoxide dismutase (SOD) and/or catalase inhibited BaP-accelerated atherosclerosis in hypercholesterolemic mice [42].*Corresponding author. Fax: +1 615 321 2949. Hyang@mmc.edu (H. Yang), Zguo@mmc.edu (Z. Guo). NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptHowever, the mechanism underlying the inhibitory action of these antioxidant enzymes on BaP-induced atherosclerosis has not been defined.It is generally accepted that the pathologic action of BaP results primarily from its reactive intermediates, which could be generated by multiple simultaneous or sequential metabolic transformations [13]. Initially, BaP is metabolized by cytochrome P450 (CYP) enzymes to epoxides, which can be hydrated to various dihydrodiols by epoxide hydrolase. 8-dihydro-BaP can be further oxidized to by CYPs [9]. BPDE is capable of binding covalently to DNA to form BPDE-DNA adducts, which is a crucial step leading to DNA mutations [10]. BaP-induced bulky DNA a...

Pathological cardiac hypertrophy is associated with nearly all forms of heart failure. It develops in response to disorders such as coronary artery disease, hypertension and myocardial infarction. Angiotensin II (Ang II) has direct effects on the myocardium and promotes hypertension. Chronic elevation of Ang II can lead to pathological cardiac hypertrophy and cardiac failure. Autophagy is an important process in the pathogenesis of cardiovascular diseases. Under physiological conditions, autophagy is an essential homeostatic mechanism to maintain the global cardiac structure function by ridding damaged cells or unwanted macromolecules and organelles. Dysregulation of autophagy may play an important role in Ang II-induced cardiac hypertrophy although conflicting reports on the effects of Ang II on autophagy and cardiac hypertrophy exist. Some studies showed that autophagy activation attenuated Ang II-induced cardiac dysfunction. Others suggested that inhibition of the Ang II induced autophagy should be protective. The discrepancies may be due to different model systems and different signaling pathway involved. Ang II-induced cardiac hypertrophy may be alleviated through regulation of autophagy. This review focuses on Ang II to highlight the molecular targets and pathways identified in the prevention and treatment of Ang II-induced pathological cardiac hypertrophy by regulating autophagy.

The carcinogenic polycylic aromatic hydrocarbon, benzo(a)pyrene (BaP), has been shown to generate reactive oxygen species (ROS) and accelerate the development of atherosclerosis. To assess the causal role of BaP-generated ROS in this process, we evaluated atherosclerotic metrics in apolipoprotein E-deficient (ApoE-/-) mice with or without overexpression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase. Without BaP, aortic atherosclerotic lesions were smaller in ApoE-/- mice overexpressing catalase or both Cu/Zn-SOD and catalase than in those overexpressing neither or Cu/Zn-SOD only. After treating with BaP or vehicle for 24 weeks, mean lesion sizes in the aortic tree and aortic root of ApoE-/- mice were increased by approximately 60% and 40%, respectively. BaP also increased the levels of oxidized lipids in the aortic tree of ApoE-/- mice and increased the frequency of advanced lesions. In contrast, BaP did not significantly alter lipid peroxidation levels or atherosclerotic lesions in the aortas of ApoE-/- mice overexpressing Cu/Zn-SOD and/or catalase. Overexpression of Cu/Zn-SOD and/or catalase also inhibited BaP-induced expression of cell adhesion molecules in aortas and endothelial cells, and reduced BaP-induced monocyte adhesion to endothelial cells. These observations, together with the functions of catalase and Cu/Zn-SOD to scavenge hydrogen peroxide and superoxide anions, implicate a causal role of ROS in the pathogenesis of BaP-induced atherosclerosis.

Individuals with a heterozygous mutation at the ataxia-telangiectasia mutated gene ( ATM ) have been reported to be predisposed to ischemic heart disease. This report examined for the first time the effect of a heterozygous ATM mutation ( ATM ؉ / ؊ ) on plasma lipid levels and atherosclerosis intensity using, and ATM ؉ / ؊ / ApoE ؊ / ؊ mice. Our data demonstrated that the plasma cholesterol and triglyceride levels in ATM ؉ / ؊ and ATM ؉ / ؊ / LDLR ؊ / ؊ mice were approximately the same as those in ATM ؉ / ؉ and ATM ؉ / ؉ / LDLR ؊ / ؊ control mice, respectively. In contrast, the plasma cholesterol level was significantly higher in ATM ؉ / ؊ / ApoE ؊ / ؊ mice than in ATM ؉ / ؉ / ApoE ؊ / ؊ control mice. In addition, the ATM ؉ / ؊ / ApoE ؊ / ؊ mice showed higher plasma apoB-48 levels, slower clearance for plasma apoB-48-carrying lipoproteins, and more advanced atherosclerotic lesions in the aorta compared with the ATM ؉ / ؉ / ApoE ؊ / ؊ mice. These novel results suggest that the product of ATM is involved in an apoE-independent pathway for catabolism of apoB-48-carrying remnants; therefore, superimposition of a heterozygous ATM mutation onto an ApoE deficiency background reduces the clearance of apoB-48-carrying lipoproteins from the blood circulation and promotes the formation of atherosclerosis. The product of the ataxia-telangiectasia mutated gene ( ATM ) has been reported to be a nuclear protein and involved in several signaling pathways, including DNA damage recognition, cell cycle control, and meiotic recombination (for review, see 1). It is now known that a fraction of ATM is also present in the cytoplasm and associated with vesicular structures such as peroxisomes (2). Ataxiatelangiectasia patients [i.e., those individuals carrying mutations at both ATM alleles ( ATM Ϫ / Ϫ )] express a variety of progressive clinical symptoms, such as cerebellar ataxia, telangiectasias, and a high incidence of cancer (for review, see 3). Cells obtained from ataxia-telangiectasia patients are more sensitive to ionizing radiation and show increased chromosomal aberrations compared with those obtained from normal subjects (4). Individuals with an ATM mutation in one allele ( ATM ϩ / Ϫ ) are spared most of the symptoms of the disease but are predisposed to cancer (5). A close review of the literature suggests that heterozygous ATM deficiency might also increase the risk of atherosclerosis-related cardiovascular diseases. For example, Swift and Chase (6) reported that the age-related mortality of heterozygous ATM carriers was increased markedly compared with the general population and that ischemic heart disease was one of the underlying causes for the early death of these individuals. Ataxia-telangiectasia patients reportedly have increased plasma cholesterol and triglyceride levels (7), which are the two major risk factors for atherosclerosis. However, ataxia-telangiectasia patients do not usually live past 20 or 30 years of age, and atherosclerosis has not been studied in these individuals.More recently, a mouse mode...