Abstract-Atherosclerosis is associated with oxidative stress and inflammation, and upregulation of LOX-1, an endothelial receptor for oxidized LDL (oxLDL). Here, we describe generation of LOX-1 knockout (KO) mice in which binding of oxLDL to aortic endothelium was reduced and endothelium-dependent vasorelaxation preserved after treatment with oxLDL (PϽ0.01 versus wild-type mice). To address whether endothelial functional preservation might lead to reduction in atherogenesis, we crossed LOX-1 KO mice with LDLR KO mice and fed these mice 4% cholesterol/10% cocoa butter diet for 18 weeks. Atherosclerosis was found to cover 61Ϯ2% of aorta in the LDLR KO mice, but only 36Ϯ3% of aorta in the double KO mice. Luminal obstruction and intima thickness were significantly reduced in the double KO mice (versus LDLR KO mice). Expression of redox-sensitive NF-B and the inflammatory marker CD68 in LDLR KO mice was increased (PϽ0.01 versus wild-type mice), but not in the double KO mice. On the other hand, antiinflammatory cytokine IL-10 expression and superoxide dismutase activity were low in the LDLR KO mice (PϽ0.01 versus wild-type mice), but not in the double KO mice. Endothelial nitric oxide synthase expression was also preserved in the double KO mice. The proinflammatory signal MAPK P38 was activated in the LDLR KO mice, and LOX-1 deletion reduced this signal.

Summary Mesp1 is regarded as the master regulator of cardiovascular development, initiating the cardiac transcription factor cascade to direct the generation of cardiac mesoderm. To define the early embryonic cell population that responds to Mesp1, we performed pulse inductions of gene expression over tight temporal windows following embryonic stem cell differentiation. Remarkably, instead of promoting cardiac differentiation in the initial wave of mesoderm, Mesp1 binds to the Tal1 (Scl) +40k enhancer and generates Flk-1+ precursors expressing Etv2 (ER71) and Tal1 that undergo hematopoietic differentiation. The second wave of mesoderm responds to Mesp1 by differentiating into PDGFRα+ precursors that undergo cardiac differentiation. Furthermore, in the absence of serum-derived factors, Mesp1 promotes skeletal myogenic differentiation. Lineage tracing revealed that the majority of yolk sac and many adult hematopoietic cells derive from Mesp1+ precursors. Thus, Mesp1 is a context-dependent determination factor, integrating stage of differentiation and signaling environment to specify different lineage outcomes.

Objective-Vascular endothelial growth factor (VEGF), a key angiogenic growth factor, stimulates angiogenesis. Low levels of reactive oxygen species (ROS) function as signaling molecules for angiogenesis. We postulated that low concentrations of oxLDL might induce low levels of ROS and initiate angiogenesis. Methods and Results-An in vitro model of tube formation from human coronary artery endothelial cells (HCAECs) was used.oxLDL (0.1, 1, 2, 5 g/mL) induced VEGF expression and enhanced tube formation. oxLDL-mediated VEGF expression and tube formation were suppressed by a specific blocking anti-LOX-1 antibody. Anti-LOX-1 antibody also reduced oxLDL-induced increase in the expression of NADPH oxidase (gp91 phox and p47 phox subunits) and subsequent intracellular ROS generation, phosphorylation of p38 as well as p44/42MAPK, and NF-B p65 expression. gp91 phox siRNA had a similar effect. The expression of VEGF and NF-B p65 induced by oxLDL was also inhibited by the specific extracellular signal-regulated kinase (ERK) 1/2 inhibitor U0126 and the p38 MAPK inhibitor SB203580. Importantly, the NADPH oxidase inhibitor apocynin, gp91 phox siRNA, U0126, and SB203580 all reduced tube formation in response to oxLDL. Conclusions-These

SummaryCaenorhabditis elegans expresses a glutathione transferase (GST) belonging to the Pi class, for which we propose the name CeGSTP2-2. CeGSTP2-2 (the product of the gst-10 gene) has the ability to conjugate the lipid peroxidation product 4-hydroxynonenal (4-HNE). Transgenic C. elegans strains were generated in which the 5′ ′ ′ ′ -flanking region and promoter of gst-10 were placed upstream of gst-10 and mGsta4 cDNAs, respectively. mGsta4 encodes the murine mGSTA4-4, an enzyme with particularly high catalytic efficiency for 4-HNE. The localization of both transgenes was similar to that of native CeGSTP2-2. The 4-HNE-conjugating activity in worm lysates increased in the order: control < mGsta4 transgenic < gst-10 transgenic; and the amount of 4-HNE-protein adducts decreased in the same order, indicating that the transgenic enzymes were active and effective in limiting electrophilic damage by 4-HNE. Stress resistance and lifespan were measured in transgenic animals (five independent lines each) and were compared with two independent control lines. Resistance to paraquat, heat shock, ultraviolet irradiation and hydrogen peroxide was greater in transgenic strains. Median lifespan of mGsta4 and gst-10 transgenic strains vs. control strains was increased by 13% and 22%, respectively. In addition to the cause-effect relationship between GST expression and lifespan observed in the transgenic lines, correlative evidence was also obtained in a series of congenic lines of C. elegans in which lifespan paralleled the 4-HNE-conjugating activity in whole-animal lysates. We conclude that electrophilic damage by 4-HNE may contribute to organismal aging.

These data challenge the simple view that FSHD is caused by a broad "opening" of D4Z4 and lead us to postulate that the region of focal demethylation is the site of action of the key D4Z4 chromatin regulatory factors that go awry in FSHD.

Aspirin treatment is associated with diminished endogenous oxidant stress and enhanced resistance to exogenous peroxide, both likely mediated by activation of antioxidant defenses. Our evidence indicates that aspirin attenuates insulin-like signaling, thus protecting against oxidative stress, postponing age-associated functional declines and extending C. elegans lifespan under benign conditions.

SUMMARY Facioscapulohumeral muscular dystrophy (FSHD) is an enigmatic disease associated with epigenetic alterations in the subtelomeric heterochromatin of the D4Z4 macrosatellite repeat. Each repeat unit encodes DUX4, a gene that is normally silent in most tissues. Besides muscular loss, most patients suffer retinal vascular telangiectasias. To generate an animal model, we introduced a doxycycline-inducible transgene encoding DUX4and 3′genomic DNA into a euchromatic region of the mouse X chromosome. Without induction, DUX4 RNA was expressed at low levels in many tissues and animals displayed a variety of unexpected dominant leaky phenotypes, including male-specific lethality. Remarkably, rare live-born males expressed DUX4 RNA in the retina and presented a retinal vascular telangiectasia. By using doxycycline to induce DUX4 expression in satellite cells, we observed impaired myogenesis in vitro and in vivo. This mouse model, which shows pathologies due to FSHD-related D4Z4 sequences, is likely to be useful for testing anti-DUX4 therapies in FSHD.

Abstract-Angiotensin II via type 1 receptor activation upregulates the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and LOX-1 activation, in turn, upregulates angiotensin II type 1 receptor expression. We postulated that interruption of this positive feedback loop might attenuate the genesis of angiotensin II-induced hypertension and subsequent cardiac remodeling. To examine this postulate, LOX-1 knockout and wild-type mice were infused with angiotensin II or norepinephrine (control for angiotensin II) for 4 weeks. Angiotensin II-, but not norepinephrine-, induced hypertension was attenuated in LOX-1 knockout mice. Angiotensin II-induced cardiac remodeling was also attenuated in LOX-1 knockout mice. Importantly, angiotensin II type 1 receptor expression was reduced, and the expression and activity of endothelial NO synthase were preserved in the tissues of LOX-1 knockout mice given angiotensin II. Reactive oxygen species generation, nicotinamide-adenine dinucleotide phosphate oxidase expression, and phosphorylation of p38 and p44/42 mitogen-activated protein kinases were also much less pronounced in the LOX-1 knockout mice given angiotensin II. These alterations in biochemical and structural abnormalities were associated with preservation of cardiac hemodynamics in the LOX-1 knockout mice. To confirm that fibroblast function is modulated in the absence of LOX-1, cardiac fibroblasts from wild-type and LOX-1 knockout mice were treated with angiotensin II. Indeed, LOX-1 knockout mice cardiac fibroblasts revealed an attenuated profibrotic response on treatment with angiotensin II. These observations provide strong evidence that LOX-1 is a key modulator of the development of angiotensin II-induced hypertension and subsequent cardiac remodeling. (Hypertension. 2008;52:556-562.)Key Words: angiotensin Ⅲ hypertension Ⅲ cardiac remodeling Ⅲ LOX-1 Ⅲ oxidative stress C ardiac remodeling is initially an adaptive response to several forms of cardiac stress states, such as hypertension. Sustained remodeling results in heart failure and is a powerful independent risk factor for cardiac morbidity and mortality. 1 Therefore, identification of the molecular mechanisms involved in cardiac remodeling is an important challenge for the cardiovascular biologists.The renin-angiotensin system and its effector hormone, angiotensin II (Ang II), have well-known endocrine properties that contribute to cardiac remodeling and heart failure. Previous studies have shown that Ang II via type 1 receptor (AT1R) activation stimulates the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). 2 In turn, activation of LOX-1 upregulates AT1R expression. 3 Activation of both AT1R and LOX-1 induces a state of oxidative stress. 4 In addition, activation of both AT1R and LOX-1 enhances the growth of cardiac fibroblasts and promotes collagen synthesis. 5,6 Although LOX-1 mRNA expression is minimal in normal arterial tissues, it is markedly upregulated in vascular tissues of spontaneously hypertensive...