The present study provides evidence that the LOX-1-MT1-MMP axis plays a crucial role in RhoA and Rac1 activation signalling pathways in ox-LDL stimulation, suggesting that this axis may be a promising target for treating endothelial dysfunction.

Background-Lysophosphatidylcholine] i increase caused by LPC. This suppressive effect was quickly reversed by geranylgeranylpyrophosphate (GGPP) and was mimicked by inhibitors of Rho and Rho kinase. LPC induced the translocation of the GTP-bound active form of RhoA into membranes within 1 minute as determined by a pull-down assay and reduced the levels of RhoA in the cytoplasm, indicating that LPC quickly increases the GTP/GDP ratio of RhoA and induces membrane translocation. Statins prevented the GTP/GDP exchange of RhoA and its membrane translocation from the cytoplasm caused by LPC, and these effects of statins were reversed by GGPP. The responses of RhoA activation to statins and GGPP concurred with their effects on Ca 2ϩ mobilization. LPC also induced a nonselective cation current after a lag. Statins prolonged the lag and decreased the current amplitude, and GGPP abolished the inhibitory effect on the current. Conclusions-LPC induced

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RhoA plays a critical signaling role in thrombin-induced endothelial dysfunction. The possible thrombin regulation of geranylgeranylation, a lipid modification, of unprocessed RhoA and the significance of the geranylgeranylation in RhoA activation in endothelial cells (ECs) are not well understood. The amounts of the unprocessed and geranylgeranylated forms of RhoA in non-stimulated cultured human aortic ECs were 31 ؎ 8 and 69 ؎ 8% total cellular RhoA, respectively (n ‫؍‬ 6, p < 0.0001), as determined by the Triton X-114 partition method. Thrombin-induced rapid conversion of most of the unprocessed RhoA into the geranylgeranylated form within 1 min through stimulating geranylgeranyltransferase I (GGTase I) activity. Thrombin-induced rapid geranylgeranylation was inhibited by acute short term (3 min) pretreatment with atorvastatin as well as by an inhibitor of GGTase I (GGTI-286). Thrombin also rapidly stimulated GTP loading of RhoA, which was blocked by acute pretreatment with either atorvastatin or GGTI-286. These observations indicate the dependence of thrombin stimulation of RhoA on the rapid geranylgeranylation of unprocessed RhoA. Importantly, the addition of geranylgeranylpyrophosphate to ECs pretreated with atorvastatin quickly reversed the atorvastatin inhibition of thrombin stimulation of RhoA. These results suggest that geranylgeranylation of unprocessed RhoA may limit thrombin-induced full activation of RhoA in ECs. Cytoskeleton analysis demonstrated that atorvastatin and GGTI-286 inhibited thrombin-induced stress fiber formation. We provide the evidence that, in thrombin-stimulated ECs, the unprocessed form of RhoA is rapidly geranylgeranylated to become the mature form, which then is converted into GTP-bound active RhoA.

Terahertz (THz) wave generation based on nonlinear frequency conversion is promising way for realizing a tunable monochromatic bright THz-wave source. Such a development of efficient and wide tunable THz-wave source depends on discovery of novel brilliant nonlinear crystal. Important factors of a nonlinear crystal for THz-wave generation are, 1. High nonlinearity and 2. Good transparency at THz frequency region. Unfortunately, many nonlinear crystals have strong absorption at THz frequency region. The fact limits efficient and wide tunable THz-wave generation. Here, we show that Cherenkov radiation with waveguide structure is an effective strategy for achieving efficient and extremely wide tunable THz-wave source. We fabricated MgO-doped lithium niobate slab waveguide with 3.8 microm of thickness and demonstrated difference frequency generation of THz-wave generation with Cherenkov phase matching. Extremely frequency-widened THz-wave generation, from 0.1 to 7.2 THz, without no structural dips successfully obtained. The tuning frequency range of waveguided Cherenkov radiation source was extremely widened compare to that of injection seeded-Terahertz Parametric Generator. The tuning range obtained in this work for THz-wave generation using lithium niobate crystal was the widest value in our knowledge. The highest THz-wave energy obtained was about 3.2 pJ, and the energy conversion efficiency was about 10(-5) %. The method can be easily applied for many conventional nonlinear crystals, results in realizing simple, reasonable, compact, high efficient and ultra broad band THz-wave sources.

This study was conducted to examine the role of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in monocyte adhesion-induced redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in endothelial cells (ECs). LOX-1 was blocked by an antibody-neutralizing LOX-1 TS92 or small interfering RNA. In cultured human aortic ECs, monocyte adhesion activated Rac1 and p47(phox), and increased NADPH oxidase activity and reactive oxygen species (ROS) generation within 30 min and NF-kappaB phosphorylation within 1 h, resulting in redox-sensitive gene expression. Akt and eNOS phosphorylation was induced 15 min after adding monocytes and returned to control level after 30 min, whereas NO production was not altered by monocyte adhesion. Blockade of LOX-1 blunted the monocyte adhesion-triggered redox-sensitive signaling pathway and Akt/eNOS phosphorylation in ECs. Both endothelial intracellular Ca2+ mobilization and Ca2+ influx caused by monocyte attachment were markedly attenuated by pretreatment of ECs with TS92. This suggests that LOX-1 is involved in redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in monocyte adhesion to ECs independent of oxidized low-density lipoprotein (ox-LDL). Furthermore, blockade of Ca2+ inhibited monocyte adhesion-triggered Rac1 and p47(phox) activation and ROS generation in ECs, whereas Ca2+ signaling was suppressed by blockade of NADPH oxidase and ROS generation. Finally, TS92 blocked the monocyte adhesion to ECs stimulated with or without tumor necrosis factor-alpha or ox-LDL. We provide evidence that LOX-1 plays a role in redox-sensitive, Akt/eNOS and Ca2+ signaling pathways in monocyte adhesion to ECs independent of the ox-LDL-LOX-1 axis.

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Objective-Ca2ϩ plays an important role in tissue factor (TF) gene expression. We investigated the role of endogenous nitric oxide (NO) in the induction of TF expression in endothelial cells (ECs) by monocyte adhesion and the mechanisms of NO action. Methods and Results-Inhibition of endogenous NO by N-nitro-L-arginine methyl ester (L-NAME) enhanced TF promoter activity and protein expression induced in human coronary ECs by monocyte adhesion, as well as EC surface TF activity. L-NAME also induced monocyte chemoattractant protein-1 (MCP-1) expression, which was blocked by an NO donor, NOC18. Exogenous MCP-1 enhanced TF expression induced by monocyte adhesion, whereas adenovirusmediated expression of the mutant MCP-1, 7ND, abolished the L-NAME enhancement of TF expression induced by monocyte adhesion. Monocyte attachment to L-NAME-treated ECs increased Ca 2ϩ influx, which was prevented by NOC18, anti-MCP-1 antibody or 7ND. These results indicate that the binding of increased MCP-1 induced by endogenous NO blockade to CCR2 mediated the enhancement of Ca 2ϩ influx only when monocytes adhered to ECs, which upregulated TF expression in ECs triggered by monocyte adhesion. Key Words: calcium Ⅲ endothelium Ⅲ nitric oxide Ⅲ MCP-1 Ⅲ tissue factor I n the early stage of atherosclerosis, monocyte chemoattractant protein-1 (MCP-1) and adherent molecules are induced in endothelial cells (ECs) under conditions of endothelial dysfunction. These result in monocyte adhesion to the ECs, which plays a crucial role in the progression of atherosclerosis. 1,2 MCP-1 also triggers firm adhesion of monocytes to vascular ECs under low flow conditions. 3 Namiki et al reported that local overexpression of MCP-1 at the vascular wall induces macrophage accumulation in rabbits. 4 In addition, Boring et al showed that the deficiency of CCR2, a receptor for MCP-1, attenuates monocyte/macrophage recruitment at vascular inflammatory sites. 5 These observations indicate that MCP-1/CCR2 plays a central role in the monocyte-EC interaction of atherogenesis. Conclusion-MCP-1/CCR2 may play a role inNitric oxide (NO) synthesized in ECs contributes to normal vascular function, including vascular relaxation, antiinflammation, and antithrombogenicity. Yang et al reported that enhanced production of NO reduces endotoxin-and cytokine-induced tissue factor (TF) expression. 6 Endothelial NO synthesis is inhibited by N -nitro-L-arginine methyl ester (L-NAME) which increases MCP-1 in ECs in vitro. 7 In vivo studies with a rat model showed that inhibition of NO synthesis by L-NAME increased MCP-1 expression and induced increased arterial thrombogenicity including upregulated expression of TF and the resultant thrombin generation. 2,8 Intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) consists of intracellular mobilization from Ca 2ϩ stores and influx via the plasma membrane. The upregulated expression of TF is inhibited by 1,2-bis(o-amino-5-fluorophenoxy)ethane-N,N,Nc,Nc-tetraacetic acid tetraacetoxymethylester (BAPTA-AM) chelation of Ca 2ϩ in cultured smooth mus...