Objective-Peroxisome proliferator-activated receptor ␥ (PPAR␥) ligands reduce lesion formation in animal models of atherosclerosis by mechanisms that have not been defined completely. We hypothesized that PPAR␥ ligands stimulate endothelial-derived nitric oxide release (·NO) to protect the vascular wall. Methods and Results-The PPAR␥ ligands, 15-deoxy-⌬ 12,14 -prostaglandin J 2 (15d-PGJ 2 ) or ciglitazone, stimulated a PPAR response element-luciferase reporter construct in transfected porcine pulmonary artery endothelial cells (PAECs), demonstrating that PPAR␥ was transcriptionally functional. Treatment with 15d-PGJ 2 or ciglitazone significantly increased release of ·NO from PAECs or human aortic endothelial cells and augmented calcium ionophore-induced ·NO release from human umbilical vein endothelial cells measured by chemiluminescence analysis of culture media. Increases in ·NO release caused by treatment with 15d-PGJ 2 occurred at 24 hours, but not after 1 to 16 hours, and were abrogated by treatment with the transcriptional inhibitor ␣-amanitin. Overexpression of PPAR␥ or treatment with 9-cis retinoic acid also enhanced PAEC ·NO release. Neither 15d-PGJ 2 nor ciglitazone altered eNOS mRNA, whereas 15d-PGJ 2 , but not ciglitazone, decreased eNOS protein. Key Words: peroxisome proliferator-activated receptor ␥ Ⅲ endothelium Ⅲ nitric oxide Ⅲ nitric oxide synthase Ⅲ thiazolidinedione T he production of nitric oxide (·NO) by vascular endothelial cells is critical for maintenance of normal vascular physiology. 1 In endothelial cells (ECs), the type III endothelial nitric oxide synthase (eNOS) produces ·NO from the amino acid L-arginine. Our preliminary observations, 2 as well as reports by others, [3][4][5] indicate that exogenous fatty acids alter EC ·NO production. The molecular mechanism contributing to fatty acid-induced alterations in EC ·NO production remain unexplored. One potential mechanism for fatty acidinduced alterations in gene expression is the activation of peroxisome proliferator-activated receptors (PPARs). Originally described in 1990, PPARs belong to the nuclear hormone receptor superfamily of ligand-activated transcription factors including steroid, thyroid, and retinoid hormone receptors. 6 Structurally diverse ligands including long-chain fatty acids, eicosanoids, thiazolidinediones, and fibrates activate PPARs, which form obligate heterodimers with the 9-cis retinoic acid receptor, RXR. 7 On ligand binding, PPARs become transcriptionally active at PPAR response elements (PPRE) and alter the expression of target genes. Conclusions-TakenPPAR␥ is expressed in vascular endothelial cells 8 -11 and smooth muscle cells. 12 The expression of PPARs in vascular wall cells suggests their potential role in vascular disease. 8 -10 Some in vitro studies suggest potential atherogenic effects of PPAR␥ activation, 8,[13][14][15] whereas other studies associate PPAR␥ with potential vascular protective effects. 16 -21 Importantly, two independent in vivo studies using the LDL receptor knockout mouse demo...

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Inducible nitric-oxide synthase (iNOS) plays a central role in the regulation of vascular function and response to injury. A central mediator controlling iNOS expression is transforming growth factor-␤ (TGF-␤), which represses its expression through a mechanism that is poorly understood. We have identified a binding site in the iNOS promoter that interacts with the nuclear heterodimer TCF11/MafG using chromatin immunoprecipitation and mutation analyses. We demonstrate that binding at this site acts to repress the induction of iNOS gene expression by cytokines. We show that this repressor is induced by TGF-␤1 and by Smad6-short, which enhances TGF-␤ signaling. In contrast, the up-regulation of TCF11/MafG binding could be suppressed by overexpression of the TGF-␤ inhibitor Smad7, and a small interfering RNA to TCF11 blocked the suppression of iNOS by TGF-␤. The binding of TCF11/MafG to the iNOS promoter could be enhanced by phorbol 12-myristate 13-acetate and suppressed by the protein kinase C inhibitor staurosporine. Moreover, the induction of TCF11/MafG binding by TGF-␤ and Smad6-short could be blocked by staurosporine, and the effect of TGF-␤ was blocked by the selective protein kinase C inhibitor calphostin C. Consistent with the in vitro data, we found suppression of TCF11 coincident with iNOS upregulation in a rat model of endotoxemia, and we observed a highly significant negative correlation between TCF11 and nitric oxide production. Furthermore, treatment with activated protein C, a serine protease effective in septic shock, blocked the down-regulation of TCF11 and suppressed endotoxin-induced iNOS. Overall, our results demonstrate a novel mechanism by which iNOS expression is regulated in the context of inflammatory activation.Nitric oxide (NO) is an important regulator and mediator of numerous and diverse processes, including vascular function, neurotransmission, tumor biology, and innate immune response (reviewed in Ref. 1). The production and balance of NO from inducible nitric-oxide synthase (iNOS) 3 play an important role in septic shock because overexpression mediates vascular collapse and cardiac dysfunction (2) and contributes to multiple organ dysfunction (reviewed in Ref.3). Selective iNOS inhibition has been shown to attenuate the hemodynamic alterations in sepsis models (4). During acute inflammatory insult, iNOS is synergistically induced by the TH-1 cytokines tumor necrosis factor-␣, interleukin-1␤, and interferon-␥ (5). Following cytokine activation and iNOS induction, vascular smooth muscle cells produces high levels of NO (6). A key factor in controlling iNOS expression is transforming growth factor-␤ (TGF-␤), which has been shown to suppress the expression of iNOS at the mRNA level in a variety of cells (6 -8), and anti-TGF antibody has been shown to block the suppression of iNOS in the vasculature (9). Moreover, in an endotoxin model of septic shock, TGF-␤1 treatment markedly reduced iNOS mRNA in several organs and blocked the lipopolysaccharide (LPS)-induced hypotension (10).Although t...

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We have investigated keratin expression in fetal, newborn and adult rat intestines by immunofluorescence staining, immunoblotting of two-dimensional gels and Northern blot analysis of total cellular RNAs. Keratin-type intermediate filaments, composed predominantly of keratin no. 19, were observed already in the undifferentiated stratified epithelium present at 15-16 days of gestation. The marked maturation and differentiation of the epithelium taking place at 18-19 days of gestation was characterized by the appearance of the differentiation-specific keratin no. 21 and by a significant increase in the relative amount of keratin no. 8. The keratin pattern typical of adult villus cells became established at the time of birth, and was marked by a considerable increase in the complexity of the keratin-related polypeptides detected on two-dimensional gels, indicative of extensive post-translational modification of all keratins. Starting at 20 days of gestation there was a major increase in the relative abundance of mRNAs coding for keratin nos. 8, 19 and 21; in contrast, the relative amount of keratin no. 18 mRNA reached a peak shortly after birth and declined to very low levels in adult intestine. These results demonstrated marked changes in keratin expression and post-translational processing taking place at key stages of intestinal development. The appearance of keratin no. 21 in coincidence with the formation of an adult-type brush border and terminal web would be consistent with it having an important role in the organization of the intermediate filament network in the apical cytoplasm of the differentiated intestinal cells.