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Nestin is an intermediate filament protein mainly expressed in muscle and neural progenitors. Recently, we reported that nestin is expressed in rat vascular smooth muscle cells (VSMCs), disappears after serum-deprivation and then is re-expressed again following EGF stimulation. As the function of nestin in VSMCs remains unknown, its anti-apoptotic function was investigated in this study. We first showed that cell viability of nestin-depleted cells following H2O2 treatments decreased by nestin RNAi. Further DNA laddering analysis and flow cytometry results demonstrated that this loss of cell viability was mediated through apoptosis. In addition, caspase-9, caspase-3 and PARP were activated in nestin-depleted VSMCs following H2O2 treatments, indicating that nestin has an upstream inhibitory effect on caspase activation. It is well known that EGF serves as a survival factor in rat VSMCs. Here, we show that the cytoprotective effect of EGF was prevented by nestin RNAi. In addition, the inhibition of Cdk5 prevented Bcl-2 phosphorylation and enhanced H2O2-induced caspase-3 activation as well as subsequent DNA fragmentation. Taken together, these results provide evidence for another cytoprotective role of EGF in that it is mediated through its stimulation of nestin expression which leads to the prevention of caspase activation by Cdk-5-induced Bcl-2 phosphorylation in rat VSMCs. [ABSTRACT FROM PUBLISHER]

Aims Macrophage-related oxidative stress plays an important role in the inflammatory process in atherosclerosis. Recently, dextromethorphan (DXM), a common cough-suppressing ingredient with a high safety profile, was found to inhibit the activation of microglia, the resident macrophage in the nervous system. We investigated whether DXM could reduce macrophage production of cytokines and superoxide and the resultant influence on atherosclerosis formation in mice. Methods and results We used in vitro and in vivo studies to evaluate the DXM inhibitory effect on oxidative stress. Dextromethorphan pretreatment significantly suppressed the production of tumour necrosis factor-α, monocyte chemoattractant protein-1, interleukin-6, interleukin-10, and superoxide in macrophage cell culture after stimulation. Indeed, DXM reduced macrophage nicotinamide adenine dinucleotide phosphate oxidase activity by decreasing membrane translocation of p47phox and p67phox through the inhibition of protein kinase C and extracellular signal-regulated kinase activation. The anti-atherosclerosis effect of DXM was tested using two animal models, apolipoprotein E (apoE)-deficient mice and a mouse carotid ligation model. Dextromethorphan treatment (10–40 mg/kg/day) for 10 weeks in apoE-deficient mice significantly reduced superoxide production in their polymorphonuclear leukocytes and aortas. It significantly decreased the severity of aortic atherosclerosis in the apoE-deficient mice and decreased carotid neointima formation after ligation in C57BL/6 mice. Conclusion Our data show that DXM, with its novel effect in reducing oxidative stress, significantly reduces atherosclerosis and neointima formation in mice. [ABSTRACT FROM AUTHOR]

: Aims Thrombomodulin (TM), a potent anticoagulant, is not detected in quiescent vascular smooth muscle cells (VSMCs). In diseased vessels, VSMC expresses TM, but the mechanisms are unclear. This study examined molecular mechanisms for TM expression in VSMCs. : Methods and results Platelet-derived growth factor-BB (PDGF-BB) induced TM expression in cultured human aortic VSMCs. PDGF-induced TM is functional in activating protein C. TM induction was eliminated by inhibitors of Src kinase, phosphatidylinositol 3-kinase (PI3-kinase), and mammalian target of rapamycin (mTOR) and by expressing dominant-negative Akt while expressing active Akt-stimulated TM expression. PDGF-BB activated the TM promoter, and the deletion of a sequence segment −394/−255 drastically reduced TM promoter activity. Transcription factor E26 transformation-specific sequence-1 (Ets-1) was upregulated by PDGF-BB in a PI3-kinase- and mTOR-dependent manner. RNA interference of Ets-1 inhibited PDGF induction of TM, and overexpressing Ets-1 increased TM expression. Chromatin immunoprecipitation and electrophoretic mobility shift assay detected increased Ets-1 binding to the TM promoter after PDGF treatment. Following carotid artery ligation of C57/BL6 mice, PDGF-BB and TM were co-expressed in the media and neointima. : Conclusion In VSMCs, PDGF-BB stimulates TM expression that is mainly mediated by Ets-1 via the Src kinase/PI3-kinase/Akt/mTOR signalling pathway. Furthermore, PDGF-BB may regulate TM expression in VSMCs during vascular remodelling. [ABSTRACT FROM AUTHOR]