Tumor Necrosis Factor α Activates the Human Plasminogen Activator Inhibitor-1 Gene through a Distal Nuclear Factor κB Site

Protein C and protein S changes in GH-deficient adults on r-HGH replacement therapy: correlations with PAI-1 and t-PA plasma levels

BACKGROUND

In the rat liver, growth hormone (GH) affects the synthesis of vitamin-K-dependent factors, including Protein C (prot.C) and protein S (prot.S), two natural anticoagulants that prevent hypercoagulable states. Adults with GH deficiency (GHD) are at risk of thrombotic events. High circulating levels of PAI-1 and t-PA, that reflect hypercoagulable states, may contribute to such risk. In GHD adults on replacement therapy with recombinant human GH (r-HGH), %Δ PAI-1 and %Δ t-PA are related to %Δ insulin changes.

OBJECTIVES

To evaluate changes in vitamin-K-dependent factors in GHD on r-HGH replacement.

METHODS

In 60 GHD adults, to relate plasma levels of vitamin-K-dependent factors with those of PAI-1, t-PA and insulin before and after 6-month (6-mo) replacement therapy with r-HGH.

RESULTS

After 6-mo r-HGH replacement, %Δ insulin enhancements occurred in 36/60 subjects. PAI-1, t-PA, Prot.C, Prot.S and FVIIact did not change in them. In the 24/40 subjects that experienced %Δ insulin reductions, Prot.C (p=0.025), Prot.S (p=0.031) and FVIIact (p=0.049) decreased significantly. PAI-1 (p=0.019) and t-PA antigen (p=0.009) behaved similarly. In a multivariate analysis, %∆ PAI-1 (β=0.436, p<0.01) was the strongest predictor of %∆ prot.S, wheras %∆ t-PA (β=0.385, p<0.008) and %∆ insulin (β=0.429, p<0.004) were the strongest predictors of %∆ prot.C. In all cases, regardless of %Δ insulin changes, FII, FVII Ag and FIX levels did not change from baseline.

CONCLUSIONS

In GHD adults on r-HGH replacement, changes in vitamin-K-dependent factors reflect a subtle adaptation of the natural anticoagulant system to PAI-1 and t-PA changes, via the response of insulin to r-HGH.

Particulate matter-induced lung inflammation increases systemic levels of PAI-1 and activates coagulation through distinct mechanisms

Background

Exposure of human populations to ambient particulate matter (PM) air pollution significantly contributes to the mortality attributable to ischemic cardiovascular events. We reported that mice treated with intratracheally instilled PM develop a prothrombotic state that requires the release of IL-6 by alveolar macrophages. We sought to determine whether exposure of mice to PM increases the levels of PAI-1, a major regulator of thrombolysis, via a similar or distinct mechanism.

Methods and Principal Findings

Adult, male C57BL/6 and IL-6 knock out (IL-6^−/−) mice were exposed to either concentrated ambient PM less than 2.5 µm (CAPs) or filtered air 8 hours daily for 3 days or were exposed to either urban particulate matter or PBS via intratracheal instillation and examined 24 hours later. Exposure to CAPs or urban PM resulted in the IL-6 dependent activation of coagulation in the lung and systemically. PAI-1 mRNA and protein levels were higher in the lung and adipose tissue of mice treated with CAPs or PM compared with filtered air or PBS controls. The increase in PAI-1 was similar in wild-type and IL-6^−/− mice but was absent in mice treated with etanercept, a TNF-α inhibitor. Treatment with etanercept did not prevent the PM-induced tendency toward thrombus formation.

Conclusions

Mice exposed to inhaled PM exhibited a TNF-α-dependent increase in PAI-1 and an IL-6-dependent activation of coagulation. These results suggest that multiple mechanisms link PM-induced lung inflammation with the development of a prothrombotic state.

1,25-Dihydroxyvitamin D₃ suppresses inflammation-induced expression of plasminogen activator inhibitor-1 by blocking nuclear factor-κB activation

Plasminogen activator inhibitor (PAI)-1 is a major fibrinolytic inhibitor. High PAI-1 is associated with increased renal and cardiovascular disease risk. Previous studies demonstrated PAI-1 down-regulation by 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), but the molecular mechanism remains unknown. Here we show that exposure of mouse embryonic fibroblasts to TNFα or LPS led to a marked induction of PAI-1, which was blunted by 1,25(OH)₂D₃, NF-κB inhibitor or p65 siRNA, suggesting the involvement of NF-κB in 1,25(OH)₂D₃-induced repression. In mouse Pai-1 promoter a putative cis-κB element was identified at -299. EMSA and ChIP assays showed that TNF-α increased p50/p65 binding to this κB site, which was disrupted by 1,25(OH)₂D₃. Luciferase reporter assays showed that PAI-1 promoter activity was induced by TNFα or LPS, and the induction was blocked by 1,25(OH)₂D₃. Mutation of the κB site blunted TNFα, LPS or 1,25(OH)₂D₃ effects. 1,25(OH)₂D₃ blocked IκBα degradation and arrested p50/p65 nuclear translocation. In mice LPS stimulated PAI-1 expression in the heart and macrophages, and the stimulation was blunted by pre-treatment with a vitamin D analog. Together these data demonstrate that 1,25(OH)₂D₃ down-regulates PAI-1 by blocking NF-κB activation. Inhibition of PAI-1 production may contribute to the reno- and cardio-protective effects of vitamin D.

Loss of metallothionein predisposes mice to diethylnitrosamine-induced hepatocarcinogenesis by activating NF-kappaB target genes

Metallothioneins (MT) are potent scavengers of free radicals that are silenced in primary hepatocellular carcinomas (HCC) of human and rodent origin. To examine whether loss of MT promotes hepatocarcinogenesis, male Mt-1 and Mt-2 double knockout (MTKO) and wild-type (WT) mice were exposed to diethylnitrosamine (DEN) and induction of HCC was monitored at 23 and 33 weeks. The size and number of liver tumors, the ratio between liver and body weight, and liver damage were markedly elevated in the MTKO mice at both time points compared with the WT mice. At 23 weeks, MTKO mice developed HCC whereas WT mice developed only preneoplastic nodules suggesting that loss of MT accelerates hepatocarcinogenesis. MTKO tumors also exhibited higher superoxide anion levels. Although NF-κB activity increased in the liver nuclear extracts of both genotypes after DEN exposure, the complex formed in MTKO mice was predominantly p50/65 heterodimer (transcriptional activator) as opposed to p50 homodimer (transcriptional repressor) in WT mice. Phosphorylation of p65 at Ser276 causing its activation was also significantly augmented in DEN-exposed MTKO livers. NF-κB targets that include early growth response genes and proinflammatory cytokines were significantly upregulated in MTKO mice. Concurrently, there was a remarkable increase (∼100-fold) in Pai-1 expression; significant increase in c-Jun, c-Fos, c-Myc, Ets2, and ATF3 expressions; and growth factor signaling that probably contributed to the increased tumor growth in MTKO mice. Taken together, these results demonstrate that MTs protect mice from hepatocarcinogen-induced liver damage and carcinogenesis, underscoring their potential therapeutic application against hepatocellular cancer.

Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models

Adverse drug reactions (ADRs) present a serious human health problem. They are major contributors to hospitalization and mortality throughout the world (Lazarou et al., 1998; Pirmohamed et al., 2004). A small fraction (less than 5%) of ADRs can be classified as "idiosyncratic." Idiosyncratic ADRs (IADRs) are caused by drugs with diverse pharmacological effects and occur at various times during drug therapy. Although IADRs affect a number of organs, liver toxicity occurs frequently and is the primary focus of this review. Because of the inconsistency of clinical data and the lack of experimental animal models, how IADRs arise is largely undefined. Generation of toxic drug metabolites and induction of specific immunity are frequently cited as causes of IADRs, but definitive evidence supporting either mechanism is lacking for most drugs. Among the more recent hypotheses for causation of IADRs is that inflammatory stress induced by exogenous or endogenous inflammagens is a susceptibility factor. In this review, we give a brief overview of idiosyncratic hepatotoxicity and the inflammatory response induced by bacterial lipopolysaccharide. We discuss the inflammatory stress hypothesis and use as examples two drugs that have caused IADRs in human patients: ranitidine and diclofenac. The review focuses on experimental animal models that support the inflammatory stress hypothesis and on the mechanisms of hepatotoxic response in these models. The need for design of epidemiological studies and the potential for implementation of inflammation interaction studies in preclinical toxicity screening are also discussed briefly.

Human catalase gene is regulated by peroxisome proliferator activated receptor-gamma through a response element distinct from that of mouse

Oxidative stress has been implicated as a causal role in atherosclerosis, microvascular complications of diabetes as well as in beta cell failure in type 2 diabetes. PPARgamma agonists not only improve insulin sensitivity but also eliminate oxidative stress. In mouse, catalase, a major antioxidant enzyme, is directly regulated by PPARgamma through two PPARgamma binding elements in its promoter. This study examined the regulatory mechanisms of catalase expression in human. Expression of catalase was significantly upregulated in human primary adipocytes upon treatment with a PPARgamma agonist. However, the mouse PPARgamma response elements are not functionally conserved in human catalase promoter. In luciferase reporter assay containing human catalase promoter, PPARgamma /RXRalpha, in combination of a PPARgamma agonist significantly transactivated 19 kb of promoter and this was mediated via a novel PPARgamma response element (PPRE) at -12 kb from transcription initiation site of human catalase gene. Electrophoretic mobility shift assay showed direct binding of PPARgamma to this PPRE. Together, our results indicate that PPARgamma regulates the expression of catalase gene in human through a PPRE distinct from that of mouse, and could explain, at least in part, the observed inhibitory effects of PPARgamma on oxidative stress in human.

Role for nuclear factor-kappaB in augmented lung injury because of interaction between hyperoxia and high stretch ventilation

High-tidal-volume mechanical ventilation and hyperoxia used in patients with acute lung injury (ALI) can induce alveolar coagulopathy and fibrin depositions within the airways. Hyperoxia has been shown to increase ventilator-induced lung injury (VILI), but the mechanisms that regulate interaction between high-tidal-volume mechanical ventilation and hyperoxia are unclear. We hypothesized that mechanical stretch with hyperoxia synergistically augmented neutrophil infiltration and production of plasminogen activator inhibitor-1 (PAI-1) via the nuclear factor-kappaB (NF-kappaB) pathway. C57BL/6 mice (n=5 per group) were exposed to high-tidal-volume (30 mL/kg) or low-tidal-volume (6 mL/kg) mechanical ventilation with room air or hyperoxia for 1 to 5h after 2-microg/g NF-kappaB inhibitor (SN-50) administration. Nonventilated mice with room air or hyperoxia served as control groups. Evans blue dye, myeloperoxidase, electrophoretic mobility shifting of nuclear protein, and inflammatory cytokine were measured. The expression of tumor necrosis factor-alpha (TNF-alpha) and PAI-1 were studied by immunohistochemistry. The addition of hyperoxia to high-tidal-volume ventilation-augmented lung injury, as demonstrated by increased microvascular leak, neutrophil migration into the lung, TNF-alpha and active PAI-1 production, DNA binding activity of NF-kappaB, and NF-kappaB activation. No statistically significant increase of neutrophil infiltration and inflammatory cytokine production was found in the mice ventilated at 6 mL/kg using hyperoxia. Hyperoxia-induced augmentation of VILI was attenuated in mice with pharmacologic inhibition of NF-kappaB activity by SN-50. We conclude that hyperoxia increased high-tidal-volume-induced cytokine production and neutrophil influx through activation of the NF-kappaB pathway.

Activator protein-2 impairs the invasion of a human extravillous trophoblast cell line

The reduced migration/invasion of extravillous trophoblasts (EVTs) is a key feature of the genesis of preeclampsia. We and others previously reported that transcriptional factors activator protein-2 (AP-2) alpha and AP-2gamma act as suppressors of tumor invasion. The present study examined the expressions of AP-2alpha and AP-2gamma in preeclamptic placenta vs. control placenta and investigated their effect on the function of EVTs. The expressions of AP-2alpha and AP-2gamma were elevated in the preeclamptic placentas in comparison with the gestational age-matched control placentas. Their expressions also increased in EVTs of the preeclamptic placentas. Thereafter, we transfected AP-2alpha or AP-2gamma into human EVT cell line, HTR-8/SVneo. The overexpression of AP-2alpha or AP-2gamma decreased the migratory and invasive abilities in HTR-8/SVneo cells. This was followed by the reduction of protease activated receptor-1 and matrix metalloproteinases and a significant induction of plasminogen activator inhibitor-1 and the tissue inhibitor of metalloproteinase-1. AP-2alpha and AP-2gamma were weakly expressed in the cultured EVTs and HTR-8/SVneo cells, whereas they were induced by TNF-alpha, which increases in preeclamptic placenta and impairs trophoblast invasion. In the presence of TNF-alpha, the invasion of the HTR-8/SVneo cells was partially restored by a blocking of AP-2 induction using small interfering RNA of AP-2. The present data suggest that AP-2 may suppress trophoblast migration and invasion, thus leading to a shallow placentation in preeclampsia.

Real-Time Monitoring of Nuclear Factor κB Activity in Cultured Cells and in Animal Models

Nuclear factor κB (NF-κB) is a transcription factor that plays a major role in many human disorders, including immune diseases and cancer. We designed a reporter system based on NF-κB responsive promoter elements driving expression of the secreted Gaussia princeps luciferase (Gluc). We show that this bioluminescent reporter is a highly sensitive tool for noninvasive monitoring of the kinetics of NF-κB activation and inhibition over time, both in conditioned medium of cultured cells and in the blood and urine of animals. NF-κB activation was successfully monitored in real time in endothelial cells in response to tumor angiogenic signaling, as well as in monocytes in response to inflammation. Further, we demonstrated dual blood monitoring of both NF-κB activation during tumor development as correlated to tumor formation using the NF-κB Gluc reporter, as well as the secreted alkaline phosphatase reporter. This NF-κB reporter system provides a powerful tool for monitoring NF-κB activity in real time in vitro and in vivo.

Activation of endothelial intrinsic NF-{kappa}B pathway impairs protein C anticoagulation mechanism and promotes coagulation in endotoxemic mice

Although the role of systemic activation of the nuclear factor kappaB (NF-kappaB) pathway in septic coagulation has been well documented, little is known about the contribution of endothelial-specific NF-kappaB signaling in this pathologic process. Here, we used transgenic mice that conditionally overexpress a mutant I-kappaBalpha, an inhibitor of NF-kappaB, selectively on endothelium, and their wild-type littermates to define the role of endothelial-specific NF-kappaB in septic coagulation. In wild-type mice, lipopolysaccharide (LPS) challenge (5 mg/kg intraperitoneally) caused markedly increased plasma markers of coagulation, decreased plasma fibrinogen level, and widespread tissue fibrin deposition, which were abrogated by endothelial NF-kappaB blockade in transgenic mice. Endothelial NF-kappaB blockade inhibited tissue factor expression in endothelial cells, but not in leukocytes. Endothelial NF-kappaB blockade did not inhibit LPS-induced tissue factor expression in heart, kidney, and liver. Endothelial NF-kappaB blockade prevented LPS down-regulation of endothelial protein C receptor (EPCR) and thrombomodulin protein expressions, inhibited tissue tumor necrosis factor-alpha converting enzyme activity, reduced EPCR shedding, and restored plasma protein C level. Our data demonstrate that endothelial intrinsic NF-kappaB signaling plays a pivotal role in septic coagulation and suggests a link between endothelial-specific NF-kappaB activation and the impairment of the thrombomodulin-protein C-EPCR anticoagulation pathway.

Unfractionated heparin and enoxaparin reduce high-stretch ventilation augmented lung injury: a prospective, controlled animal experiment

Introduction

Dysregulation of coagulation and local fibrinolysis found in patients with acute lung injury often results in the need for the support of mechanical ventilation. High-tidal-volume mechanical ventilation can increase lung damage and suppression of fibrinolytic activity, but the mechanisms are unclear. We hypothesized that subcutaneous injections of unfractionated heparin and enoxaparin would decrease neutrophil infiltration, lung edema, and plasminogen-activator inhibitor-1 (PAI-1) production in mice exposed to high-tidal-volume ventilation.

Methods

Male C57BL/6 mice, weighing 20 to 25 g, were exposed to either high-tidal-volume (30 ml/kg) or low-tidal-volume (6 ml/kg) mechanical ventilation with room air for 1 to 5 hours after 200 IU/kg or 400 IU/kg unfractionated heparin and 4 mg/kg or 8 mg/kg enoxaparin administration. Nonventilated mice served as a control group. Evan blue dye, lung wet- to dry-weight ratio, histopathologic grading of epithelium, myeloperoxidase, and gene expression of PAI-1 were measured. The expression of PAI-1 was studied by immunohistochemistry.

Results

High-tidal-volume ventilation induced increased microvascular permeability, neutrophil influx, PAI-1 mRNA expression, production of PAI-1 protein, and positive staining of PAI-1 in epithelium in a dose-dependent manner. Lung injury induced by high-tidal-volume ventilation was attenuated with PAI-1-deficient mice and pharmacologic inhibition of PAI-1 activity by low-dose unfractionated heparin and enoxaparin.

Conclusions

We conclude that high-tidal-volume mechanical ventilation increased microvascular permeability, neutrophil influx, lung PAI-1 mRNA expression, production of active PAI-1. The deleterious effects were attenuated by low-dose unfractionated heparin or enoxaparin treatment. Understanding the protective mechanism of unfractionated heparin and enoxaparin related to the reduction of PAI-1 may afford further knowledge of the effects of mechanical forces in the lung and development of possible therapeutic strategies involved in acute lung injury.

Unexpected Pulseless Disease Associated With Recurrent Venous Thromboembolisms

Venous thromboembolic disease is a well-documented complication of Klinefelter’s syndrome, even if mechanisms underlying this prothrombotic state have not been conclusively established. On the contrary, arterial thrombosis is far less frequent, and a case of a patient with Klinefelter’s syndrome presenting with simultaneous venous thrombtoembolic disease and a complete thrombosis of the left subclavian artery is presented. Elevated levels of type 1 plasminogen activator inhibitor, in the absence of other usual thrombophilic abnormalities, raise the question of the role played by this inhibitor of the fibrinolysis in the arterial and venous thromboses presented by this patient.

Intracellular signaling pathways involved in inhibition of PAI-1 expression by CNP in endothelial cells

PAI-1 is a multifunctional protein stimulated by infectious agents and its activation is mediated by inflammatory cytokines such as TNFalpha. Recent studies demonstrate that natriuretic peptides, particularly C-type (CNP), can affect PAI-1 expression in bovine aortic smooth muscle cells and rat aortic endothelial cells. We have previously shown that CNP inhibits both basal and TNFalpha induced expression of PAI-1 in human endothelial cells. Herein, we describe mechanism by which CNP modulates signaling engaged in controlling PAI-1 expression in human endothelial cells. To examine which pathway initiated by TNFalpha is influenced, we tested kinase activity of MAP, PI3K/AKT and involvement of cGMP in endothelial cells exposed to CNP. CNP significantly increased cGMP level in endothelial cells. Its analogue, 8-Br-cGMP alone had no effect but significantly inhibited TNFalpha induced expression of PAI-1. Similarly, CNP and the inhibitors of ERK1/2 (PD098059) and PI3K (LY294002) attenuated PAI-1 expression induced by TNFalpha. CNP almost abolished TNFalpha induced phosphorylation of ERK1/2 but did not affect JNK phosphorylation, indicating that its effect on ERK1/2 was specific. These data suggest that CNP might function as the natural defense of vascular wall against cytokine induced PAI-1 release through its ability to inactivate PI3K/AKT and MEK/ERK pathways.

PAI-1 and functional blockade of SNAI1 in breast cancer cell migration

Introduction

Snail, a family of transcriptional repressors implicated in cell movement, has been correlated with tumour invasion. The Plasminogen Activation (PA) system, including urokinase plasminogen activator (uPA), its receptor and its inhibitor, plasminogen activator inhibitor type 1(PAI-1), also plays a key role in cancer invasion and metastasis, either through proteolytic degradation or by non-proteolytic modulation of cell adhesion and migration. Thus, Snail and the PA system are both over-expressed in cancer and influence this process. In this study we aimed to determine if the activity of SNAI1 (a member of the Snail family) is correlated with expression of the PA system components and how this correlation can influence tumoural cell migration.

Methods

We compared the invasive breast cancer cell-line MDA-MB-231 expressing SNAI1 (MDA-mock) with its derived clone expressing a dominant-negative form of SNAI1 (SNAI1-DN). Expression of PA system mRNAs was analysed by cDNA microarrays and real-time quantitative RT-PCR. Wound healing assays were used to determine cell migration. PAI-1 distribution was assessed by immunostaining.

Results

We demonstrated by both cDNA microarrays and real-time quantitative RT-PCR that the functional blockade of SNAI1 induces a significant decrease of PAI-1 and uPA transcripts. After performing an in vitro wound-healing assay, we observed that SNAI1-DN cells migrate more slowly than MDA-mock cells and in a more collective manner. The blockade of SNAI1 activity resulted in the redistribution of PAI-1 in SNAI1-DN cells decorating large lamellipodia, which are commonly found structures in these cells.

Conclusions

In the absence of functional SNAI1, the expression of PAI-1 transcripts is decreased, although the protein is redistributed at the leading edge of migrating cells in a manner comparable with that seen in normal epithelial cells.

Computational identification of the normal and perturbed genetic networks involved in myeloid differentiation and acute promyelocytic leukemia

A dissection of the genetic networks and circuitries is described for two form of leukaemia. Integrating transcription factor binding and gene expression profiling, networks are revealed that underly this important human disease.

Background

Acute myeloid leukemia (AML) comprises a group of diseases characterized by the abnormal development of malignant myeloid cells. Recent studies have demonstrated an important role for aberrant transcriptional regulation in AML pathophysiology. Although several transcription factors (TFs) involved in myeloid development and leukemia have been studied extensively and independently, how these TFs coordinate with others and how their dysregulation perturbs the genetic circuitry underlying myeloid differentiation is not yet known. We propose an integrated approach for mammalian genetic network construction by combining the analysis of gene expression profiling data and the identification of TF binding sites.

Results

We utilized our approach to construct the genetic circuitries operating in normal myeloid differentiation versus acute promyelocytic leukemia (APL), a subtype of AML. In the normal and disease networks, we found that multiple transcriptional regulatory cascades converge on the TFs Rora and Rxra, respectively. Furthermore, the TFs dysregulated in APL participate in a common regulatory pathway and may perturb the normal network through Fos. Finally, a model of APL pathogenesis is proposed in which the chimeric TF PML-RARα activates the dysregulation in APL through six mediator TFs.

Conclusion

This report demonstrates the utility of our approach to construct mammalian genetic networks, and to obtain new insights regarding regulatory circuitries operating in complex diseases in humans.

Oxidative stress, plasminogen activator inhibitor 1, and lung fibrosis

Fibrosis is characterized by excessive accumulation of extracellular matrix (ECM) in basement membranes and interstitial tissues, resulting from increased synthesis or decreased degradation of ECM or both. The plasminogen activator/plasmin system plays an important role in ECM degradation, whereas the plasminogen activator inhibitor 1 (PAI-1) is a physiologic inhibitor of plasminogen activators. PAI-1 expression is increased in the lung fibrotic diseases and in experimental fibrosis models. The deletion of the PAI-1 gene reduces, whereas the overexpression of PAI-1 enhances, the susceptibility of animals to lung fibrosis induced by different stimuli, indicating an important role of PAI-1 in the development of lung fibrosis. Many growth factors, including transforming growth factor beta (TGF-beta) and tumor necrosis factor alpha (TNF-alpha), as well as other chemicals/agents, induce PAI-1 expression in cultured cells and in vivo. Reactive oxygen and nitrogen species (ROS/RNS) have been shown to mediate the induction of PAI-1 by many of these stimuli. This review summarizes some recent findings that help us to understand the role of PAI-1 in the development of lung fibrosis and ROS/RNS in the regulation of PAI-1 expression during fibrogenesis.

A study on the action of vitamin E supplementation on plasminogen activator inhibitor type 1 and platelet nitric oxide production in type 2 diabetic patients

BACKGROUND AND AIM

Type 2 diabetic (T2DM) patients show decreased fibrinolysis, mainly linked to high plasminogen activator inhibitor type 1 (PAI-1) production, together with a reduced bioavailability of nitric oxide and an impairment in Na(+)/K(+)-ATPase activity possibly involved in increased cardiovascular risk. Vitamin E is the major natural lipid-soluble antioxidant in human plasma. The present work was conducted in order to measure PAI-1, ICAM and VCAM-1 plasma levels, platelet nitric oxide production and membrane Na(+)/K(+)-ATPase activity in type 2 diabetic subjects treated with vitamin E (500 IU/day) for 10 weeks and then followed for other 20 weeks.

METHODS AND RESULTS

Thirty-seven T2DM patients (24 males and 13 females) were studied. None of them were affected by any other disease or diabetic complications. Significant differences were detected for PAI-1 antigen (p<0.001), PAI-1 activity (p<0.001), nitric oxide (NO) production (p<0.001), and Na(+)/K(+)-ATPase activity (p<0.001) among the 4 phases of the study. A significant decrease both in ICAM and VCAM-1 plasma levels was also found at the 10th week compared with baseline (respectively p<0.001 and p<0.05).

CONCLUSION

Our data suggest that vitamin E counteracts endothelial activation in T2DM patients possibly representing a new tool for endothelial protection.

Sepsis

Sepsis is a clinical syndrome defined by a systemic response to infection. With progression to sepsis-associated organ failure (ie, severe sepsis) or hypotension (ie, septic shock) mortality increases. Sepsis is a cause of considerable mortality, morbidity, cost, and health care utilization. Abnormalities in the inflammation, immune, coagulation, oxygen delivery, and utilization pathways play a role in organ dysfunction and death. Early identification of septic patients allows for evidence-based interventions, such as prompt antibiotics, goal-directed resuscitation, and activated protein C. Appropriate care for sepsis may be more easily delivered by dividing this clinical entity into various stages and with changes in structures of delivery that extend across traditional boundaries. Better description of the molecular basis of the disease process also will allow for more targeted therapies.

EGF regulates plasminogen activator inhibitor-1 (PAI-1) by a pathway involving c-Src, PKCdelta, and sphingosine kinase 1 in glioblastoma cells

Patients with gliomas expressing high levels of epidermal growth factor receptor (EGFR) and plasminogen activator inhibitor-1 (PAI-1) have a shorter overall survival prognosis. Moreover, EGF enhances PAI-1 expression in glioma cells. Although multiple known signaling cascades are activated by EGF in glioma cells, we show for the first time that EGF enhances expression of PAI-1 via sequential activation of c-Src, protein kinase C delta (PKCdelta), and sphingosine kinase 1 (SphK1), the enzyme that produces sphingosine-1-phosphate. EGF induced rapid phosphorylation of c-Src and PKCdelta and concomitant translocation of PKCdelta as well as SphK1 to the plasma membrane. Down-regulation of PKCdelta abolished EGF-induced SphK1 translocation and up-regulation of PAI-1 by EGF; whereas, down-regulation of PKCalpha had no effect on the EGF-induced PAI-1 activation but enhanced its basal expression. Similarly, inhibition of c-Src activity by PP2 blocked both EGF-induced translocation of SphK1 and PKCdelta to the plasma membrane and up-regulation of PAI-1 expression. Furthermore, SphK1 was indispensable for both EGF-induced c-Jun phosphorylation and PAI-1 expression. Collectively, our results provide a functional link between three critical downstream targets of EGF, c-Src, PKCdelta, and SphK1 that have all been implicated in regulating motility and invasion of glioma cells.

Markedly impaired fibrinolytic balance contributes to cardiovascular risk in adults with growth hormone deficiency

CONTEXT

Adults with GH deficiency (GHD) have multiple cardiovascular risk factors, including an unfavorable lipid profile and body composition as well as impairments in endothelial function and cardiac performance. We hypothesized that GHD is associated with elevated levels of plasminogen activator inhibitor-1 (PAI-1), the major inhibitor of plasminogen activation in the circulation.

OBJECTIVE

The objective of the study was to determine the fibrinolytic profile of adults with GHD in comparison with controls.

STUDY DESIGN AND PARTICIPANTS

This was a prospective, observational study including 12 adults with GHD. Twelve gender-, age-, and body mass index-matched adults served as controls.

MAIN OUTCOME MEASURES

The primary outcome measures were circadian plasma PAI-1 antigen with corresponding tissue-plasminogen activator (tPA) activity values. Endothelial function was assessed by flow-mediated vasodilation and fibrinolytic potential by venous occlusion test.

RESULTS

Adults with GHD exhibited an unfavorable 24-h fibrinolytic profile characterized by a mean 62% elevation in PAI-1 antigen (2.77 ng/ml after adjustment for baseline PAI-1; P = 0.049) in the setting of a mean 24% reduction in tPA activity (-0.17 IU/ml after adjustment for baseline tPA; P = 0.003). Fibrinolytic response was defective in GHD, as demonstrated by a sustained elevation in PAI-1 activity greater than 4 IU/ml after venous occlusion [7.2 IU/ml (interquartile range 0.8-17.4); P = 0.018]. Endothelial function was impaired in GHD, as quantified by percent flow-mediated vasodilation over 120 sec [area under the curve 3.8 (interquartile range -2.4 to 7.9) vs. 12.8 (interquartile range 2.1-19.4); P = 0.043].

CONCLUSIONS

Adults with GHD demonstrate alterations in plasma fibrinolytic balance, including elevated levels of PAI-1 antigen with decreased tPA activity. These changes may contribute to the increased cardiovascular morbidity within this population.

Upstream stimulating factor-1 mediates the E-box-dependent transcriptional repression of the plasminogen activator inhibitor-1 gene in human mast cells

Plasminogen activator inhibitor (PAI)-1 promotes development of asthma. PAI-1 mRNA and protein are markedly induced in activated mast cells (MCs), a major effector cell type in asthma. However, regulatory mechanisms of PAI-1 transcription in MCs are unknown. We present first evidence that PAI-1 is transcriptionally regulated in human MCs (hMCs). In addition to three enhancer regions, we demonstrated that the E-box at -566 bp to -561 bp is the negative regulatory element, and the specific and constitutive binding of the upstream stimulating factor-1 to this E-box is the key mechanism of the negative regulation of PAI-1 expression in hMCs.

The HMG-CoA reductase inhibitor rosuvastatin inhibits plasminogen activator inhibitor-1 expression and secretion in human adipocytes

Human preadipocytes and adipocytes are known to produce the proatherogenic factor PAI-1 and proinflammatory cytokines, and obesity was found to be state of increased adipose production of these factors. In the present study, we investigated the effect of rosuvastatin on the regulation of PAI-1 gene expression in human adipocytes. Human preadipocytes, adipocytes in primary culture and the SGBS cell line were used as cell models. Cells were transfected using various constructs and promoter activity was measured as luciferase activity. PAI-1 expression was measured by quantitative RT-PCR and ELISA. Rosuvastatin inhibited PAI-1 mRNA expression and secretion of the protein in a concentration-dependent manner. This effect was reversed by isoprenoids. Addition of MEK-inhibitors and NFkappaB inhibitors also reduced PAI-1 expression and PAI-1 promoter luciferase activity. Further experiments revealed that rosuvastatin down-regulated the MEKK-1 mediated activation of the PAI-1 promoter. In conclusion our data suggest that rosuvastatin inhibits PAI-1 expression and release from human adipocytes via a MEKK-1-dependent but not a NFkappaB-dependent mechanism.

Fibrinolysis, inflammation, and regulation of the plasminogen activating system

The maintenance of a given physiological process demands a coordinated and spatially regulated pattern of gene regulation. This applies to genes encoding components of enzyme cascades, including those of the plasminogen activating system. This family of proteases is vital to fibrinolysis and dysregulation of the expression pattern of one or more of these proteins in response to inflammatory events can impact on hemostasis. Gene regulation occurs on many levels, and it is apparent that the genes encoding the plasminogen activator (fibrinolytic) proteins are subject to both direct transcriptional control and significant post-transcriptional mechanisms. It is now clear that perturbation of these genes at either of these levels can dramatically alter expression levels and have a direct impact on the host's response to a variety of physiological and pharmacological challenges. Inflammatory processes are well known to impact on the fibrinolytic system and to promote thrombosis, cancer and diabetes. This review discusses how inflammatory and other signals affect the transcriptional and post-transcriptional expression patterns of this system, and how this modulates fibrinolysis in vivo.

Human chorionic gonadotrophin attenuates NF-kappaB activation and cytokine expression of endometriotic stromal cells

Recently, a clinical study provided evidence that treatment of endometriotic women with human chorionic gonadotrophin (hCG) alleviates disease-related pain and sleeplessness suggesting therapeutic effects of the hormone. Since endometriosis is associated with aberrant concentrations of inflammatory mediators in the peritoneal fluid, we investigated whether hCG may affect cytokine-dependent activation of the key-regulatory transcription factor NF-kappaB and expression of two nuclear factor kappa B (NF-kappaB)-inducible genes, tumour necrosing factor (TNF-alpha) and interleukin (IL)-1beta, in stromal cells isolated from ectopic endometriotic tissues. Electrophoretic mobility shift assay revealed that treatment of these cultures with the urinary preparation hCG-A suppressed TNF-alpha- or IL-1beta-induced NF-kappaB DNA-binding activity, whereas another urinary hCG preparation (hCG-B) was less effective. Recombinant alphahCG or epidermal growth factor (EGF), a contaminant of some urinary hCG preparations, did not alter cytokine-dependent NF-kappaB activation. Immunofluorescene of its p65 subunit revealed that pre-incubation with hCG-A strongly decreased TNF-alpha-dependent nuclear expression of NF-kappaB. Accordingly, hCG-A diminished IL-1beta-induced TNF-alpha transcript levels and protein release measured by quantitative real-time PCR and enzyme-linked immunosorbent assay. The hormone also attenuated TNF-alpha-dependent mRNA expression of IL-1beta. Western blot analyses revealed that hCG-A impaired TNF-alpha-mediated phosphorylation and degradation of the inhibitor IkappaBalpha suggesting that the hormone may reduce nuclear import of NF-kappaB by stabilizing its inhibitor. The data suggest that hCG attenuates inflammation-dependent NF-kappaB activation and cytokine expression that could provide one explanation for the beneficial role of the hormone in endometriotic patients.

Identification of NF-kappaB responsive elements in follistatin related gene (FLRG) promoter

Follistatin related gene (FLRG) has been previously identified from a chromosomal translocation observed in a B-cell chronic lymphocytic leukemia (B-CLL). FLRG (alternative names: follistatin-related protein, FSRP/follistatin-like-3, FSTL3) is a secreted glycoprotein highly similar to follistatin. Like follistatin, FLRG is involved in the regulation of various biological effects through its binding to members of the transforming growth factor beta (TGFbeta) superfamily such as activin A and myostatin. We have previously shown that TGFbeta and activin A are potent inducers of FLRG transcriptional activation through the Smad proteins. Using a biochemical approach, we investigated whether tumor necrosis factor alpha (TNFalpha) could regulate FLRG expression since TNFalpha plays a critical role in hematopoietic malignancies. We demonstrate that TNFalpha activates FLRG expression at the transcriptional level. This activation depends on a promoter region containing four 107-108 bp DNA repeats, which are evolutionary conserved in primates. These repeats carry a strong phylogenetic signal, which is not common among non-coding sequences. Each DNA repeat contains one TNFalpha responsive element (5'-GGGAGAG/TTCC-3') able to bind nuclear factor kappaB (NF-kappaB) transcription factors. We also show that TGFbeta, through the Smad proteins, potentates the effect of TNFalpha on FLRG expression. This cooperation is unexpected since TGFbeta and TNFalpha usually have opposite biological effects. In all, this work brings new insights in the understanding of FLRG regulation by cytokines and growth factors. It opens attractive perspectives of research that should allow us to better understand the role of FLRG during tumorigenesis.

High glucose induces plasminogen activator inhibitor-1 expression through Rho/Rho-kinase-mediated NF-kappaB activation in bovine aortic endothelial cells

Recently, it has become evident that elevated levels of plasminogen activator inhibitor-1 (PAI-1) are associated with myocardial infarction and stroke, especially in patients with diabetes. The molecular mechanisms involved in hyperglycemia-induced PAI-1 expression in bovine aortic endothelial cells (BAEC) were investigated. PAI-1 expression in BAEC was significantly increased in accordance with the concentration of glucose in media from 5.7 mM to 23 mM. Stimulation with high glucose (23 mM) significantly increased small GTPase Rho A activation. Pretreatment with a Rho-kinase inhibitor, Y-27632 (1-10 microM), significantly blocked high glucose-induced PAI-1 expression. NF-kappaB activity determined using the luciferase reporter gene assay was significantly enhanced by high glucose, and pretreatment with Y-27632 inhibited high glucose-induced PAI-1 expression at the basal level. An inhibitor of NF-kappaB action, namely parthenolide (0.1 microM), BAY 11-7082 (5 microM) and SN50 (1 microM), significantly blocked high glucose-mediated PAI-1 expression to a level with low glucose (5.7 mM). These data suggested that high glucose-induced PAI-1 expression in endothelial cells is mediated by NF-kappaB activation through the Rho/Rho-kinase pathway. Inhibition of Rho/Rho-kinase signaling might be a novel target for diabetes and metabolic syndrome.

IL-1 and IL-6 induce hepatocyte plasminogen activator inhibitor-1 expression through independent signaling pathways converging on C/EBPδ

To elucidate signaling pathways activated by IL-1 and IL-6 that contribute to increased expression of plasminogen activator inhibitor-1 (PAI-1), we studied human hepatoma (HepG2) cells and primary mouse hepatocytes. HepG2 cell PAI-1 mRNA increased in response to IL-1β, IL-6, and IL-1β plus IL-6 as shown by real-time PCR. Activity of the transiently transfected PAI-1 promoter (−829 to +36 bp) increased as well. Systematic promoter deletion assays showed that the region from −239 to −210 bp containing a putative CCAAT-enhancer binding protein (C/EBP) binding site was critical. Point mutations in this region abolished the IL-1β and IL-6 responses. Antibody interference electrophoretic mobility shift assays showed that C/EBPδ (but not C/EBPα or C/EBPβ) binding and protein were increased by IL-1β, IL-6, and IL-1β plus IL-6 in HepG2 cells. IL-1β and IL-6 increased expression of both PAI-1 mRNA and C/EBPδ mRNA in mouse primary hepatocytes as well. Downregulation of C/EBPδ induced with small interfering RNA (siRNA) decreased secretion of PAI-1. As judged from results obtained with inhibitors, signal transduction in all three of the mitogen-activated protein kinase pathways was involved in IL-1-inducible PAI-1 expression. By contrast, JAK signaling was responsible for the IL-6-induced inducible expression. Thus IL-1 and IL-6 exert directionally similar effects on PAI-1 expression, but the induction involves distinct signaling pathways with a final common mediator, C/EBPδ.

The orphan nuclear receptor Rev-erb alpha regulates circadian expression of plasminogen activator inhibitor type 1

Plasminogen activator inhibitor type 1 (PAI-1) is a major physiologic regulator of the fibrinolytic system and has recently gained recognition as a modulator of inflammation and atherosclerosis. PAI-1 exhibits circadian rhythmicity in its expression, peaking in the early morning, which is associated with increased risk for cardiovascular events. However, the mechanisms that determine PAI-1 circadian rhythmicity remain poorly understood. We discovered that the orphan nuclear receptor Rev-erb alpha, a core component of the circadian loop, represses human PAI-1 gene expression through two Rev-erb alpha binding sites in the PAI-1 promoter. Mutations of these sites, as well as RNA interference targeting endogenous Rev-erb alpha and its corepressors, led to increased expression of the PAI-1 gene. Furthermore, glycogen synthase kinase 3beta (GSK3beta) contributes to pai-1 repression by phosphorylating and stabilizing Rev-erb alpha protein, which can be blocked by lithium. Interestingly, serum shock generated circadian oscillations in PAI-1 mRNA in NIH3T3 cells, suggesting that PAI-1 is a direct output gene of the circadian loop. Ectopic expression of a stabilized form of Rev-erb alpha that mimics GSK3beta phosphorylation dramatically dampened PAI-1 circadian oscillations. Thus, our results suggest that Rev-erb alpha is a major determinant of the circadian PAI-1 expression and a potential modulator of the morning susceptibility to myocardial infarction.

The complement component C5a induces the expression of plasminogen activator inhibitor-1 in human macrophages via NF-kappaB activation

BACKGROUND

Atherosclerosis is considered to be a chronic inflammatory disorder. Activation of the complement cascade is a major aspect of chronic inflammatory diseases. Complement components were identified in atherosclerotic plaques, and a correlation between adverse events and C5a plasma levels was found. These findings support the notion that complement activation contributes to development and progression of atherosclerotic lesions.

OBJECTIVES

We investigated whether complement components C3a and C5a regulate plasminogen activator inhibitor (PAI-1) in human macrophages.

METHODS

Human monocyte-derived macrophages (MDM) and human plaque macrophages were cultured and incubated with the complement component C5a.

RESULTS

C5a increased PAI-1 up to 11-fold in human MDM and up to 2.7-fold in human plaque macrophages. These results were confirmed at the mRNA level using real time-polymerase chain reaction. Pertussis toxin or anti-C5aR/CD88 antibody completely abolished the effect of recombinant human C5a on PAI-1 production, suggesting a role of the C5a receptor. Experiments with antitumor necrosis factor (TNF)-alpha antibodies and tiron showed that the effect of C5a was not mediated by TNF-alpha or oxidative burst. Furthermore C5a induced NF-kappaB binding to the cis element in human macrophages and the C5a-induced increase in PAI-1 was completely abolished by an NF-kappaB inhibitor.

CONCLUSIONS

We conclude that C5a upregulates PAI-1 in macrophages via NF-kappaB activation. We hypothesize that - if operative in vivo- this effect could favor thrombus development and thrombus stabilization in the lesion area. On the other hand one could speculate that C5a-induced upregulation of PAI-1 in plaque macrophages could act as a defense mechanism against plaque destabilization and rupture.

Identification of a peroxisome proliferator responsive element (PPRE)-like cis-element in mouse plasminogen activator inhibitor-1 gene promoter

PAI-1 is expressed and secreted by adipose tissue which may mediate the pathogenesis of obesity-associated cardiovascular complications. Evidence is presented in this report that PAI-1 is not expressed by preadipocyte, but significantly induced during 3T3-L1 adipocyte differentiation and the PAI-1 expression correlates with the induction of peroxisome proliferator-activated receptor gamma (PPARgamma). A peroxisome proliferator responsive element (PPRE)-like cis-element (-206TCCCCCATGCCCT-194) is identified in the mouse PAI-1 gene promoter by electrophoretic mobility shift assay (EMSA) combined with transient transfection experiments; the PPRE-like cis-element forms a specific DNA-protein complex only with adipocyte nuclear extracts, not with preadipocyte nuclear extracts; the DNA-protein complex can be totally competed away by non-labeled consensus PPRE, and can be supershifted with PPARgamma antibody. Mutation of this PPRE-like cis-element can abolish the transactivation of mouse PAI-1 promoter mediated by PPARgamma. Specific PPARgamma ligand Pioglitazone can significantly induce the PAI-1 expression, and stimulate the secretion of PAI-1 into medium.

NF-kappa B activation as a pathological mechanism of septic shock and inflammation

The pathophysiology of sepsis and septic shock involves complex cytokine and inflammatory mediator networks. NF-kappaB activation is a central event leading to the activation of these networks. The role of NF-kappaB in septic pathophysiology and the signal transduction pathways leading to NF-kappaB activation during sepsis have been an area of intensive investigation. NF-kappaB is activated by a variety of pathogens known to cause septic shock syndrome. NF-kappaB activity is markedly increased in every organ studied, both in animal models of septic shock and in human subjects with sepsis. Greater levels of NF-kappaB activity are associated with a higher rate of mortality and worse clinical outcome. NF-kappaB mediates the transcription of exceptional large number of genes, the products of which are known to play important roles in septic pathophysiology. Mice deficient in those NF-kappaB-dependent genes are resistant to the development of septic shock and to septic lethality. More importantly, blockade of NF-kappaB pathway corrects septic abnormalities. Inhibition of NF-kappaB activation restores systemic hypotension, ameliorates septic myocardial dysfunction and vascular derangement, inhibits multiple proinflammatory gene expression, diminishes intravascular coagulation, reduces tissue neutrophil influx, and prevents microvascular endothelial leakage. Inhibition of NF-kappaB activation prevents multiple organ injury and improves survival in rodent models of septic shock. Thus NF-kappaB activation plays a central role in the pathophysiology of septic shock.

Identification of TNF-alpha-responsive NF-kappaB p65-binding element in the distal promoter of the mouse serine protease inhibitor SerpinE2

Serine protease inhibitor SerpinE2 is known as a cytokine-inducible gene. Here, we investigated whether tumor necrosis factor alpha-(TNF-alpha)-induced expression of SerpinE2 is mediated by the nuclear factor-kappaB (NF-kappaB) p65 subunit. Both steady state and TNF-alpha-induced expression of SerpinE2 mRNA were abrogated in p65-/- murine embryonic fibroblasts (MEFs). Reconstitution with wild-type p65 rescued SerpinE2 mRNA expression in an IkappaB kinase beta-dependent manner. Electrophoresis mobility shift assay and ChIP assay demonstrated that p65 bound to the kappaB-like DNA sequence located at approximately -9 kbp in the SerpinE2 promoter. In addition, TNF-alpha stimulated luciferase gene expression driven by the kappaB-like element in the reconstituted MEFs, but not in p65-/- MEFs. These results indicated that activation of NF-kappaB p65 plays an important role in TNF-alpha-induced expression of SerpinE2.

Transforming growth factor‐β1 enhances the antifibrinolytic and prothrombotic state of growing endothelial cells in a cell cycle‐specific manner

Cell cycle-dependent modulation of protein expression may influence the balance of antithrombotic and prothrombotic properties of endothelial cells. In the present study, we examined the regulation of prothrombotic and antithrombotic molecules by transforming growth factor-beta1 (TGF-beta1) during distinct phases of the cell cycle in human umbilical vein endothelial cells. In the absence of TGF-beta1, the expression of thrombomodulin, the plasminogen activators u-PA and t-PA, and their inhibitor PAI-1 was significantly increased in the S/G2 compared to the G1 phase. Treatment of endothelial cells with TGF-beta1, however, resulted in elevated expression of PAI-1 specifically in the S/G2 phase, while t-PA and u-PA increased to the same extent in both the G1 and S/G2 phase. These findings demonstrate that the expression of a subset of hemostatically relevant proteins is regulated during endothelial cell cycle and that TGF-beta1 can differentially modulate cell cycle-controlled protein expression.

TNFalpha-mediated induction of PAI-1 restricts invasion of HTR-8/SVneo trophoblast cells

The pro-inflammatory cytokine TNFalpha has numerous effects on placental trophoblasts. Here, we investigated the effects of the cytokine on gene expression and function of the extravillous trophoblast cell line HTR-8/SVneo. Wound healing and Matrigel invasion assays demonstrate that TNFalpha impairs motility and invasiveness. In contrast, counting of cumulative cell numbers and FACS analyses revealed that the cytokine did neither affect proliferation nor distribution of cell cycle phases. Immunocytochemistry of the cytokeratin 18 neo-epitope suggests that TNFalpha did not induce apoptosis in HTR-8/SVneo cells. Gelatine zymography and enzyme activity assays of supernatants of TNFalpha-treated cells demonstrate elevation of the pro- and active form of MMP-9 suggesting that increased expression of the protease cannot overcome the TNFalpha-inhibitory effect on cell invasion. Semi-quantitative RT-PCR analyses suggest that the cytokine may not alter mRNA levels of uPA and tPA. However, elevated expression of PAI-1 was detected by RT-PCR, as well as by Northern and Western blot analyses. Supplementation of PAI-1-blocking antibodies restored invasion of TNF-alpha-incubated HTR-8/SVneo cells through Matrigel-coated transwells. In addition, immunocytochemistry revealed nuclear accumulation of the p65 subunit of NFkappaB in the presence of the cytokine. EMSA indicated TNFalpha-induced binding of the inflammatory transcription factor to an NFkappaB consensus sequence and to the NFkappaB recognition site located in the PAI-1 promoter. The data suggest that TNFalpha restricts trophoblast invasion mainly by increasing the expression of PAI-1. Induction of the inhibitor may involve TNFalpha-stimulated activation of NFkappaB.

Oxidative stress provokes atherogenic changes in adipokine gene expression in 3T3-L1 adipocytes

Increased oxidative stress has been associated with obesity-related disorders. In this study, we investigated how oxidative stress, in different ways of exposure, regulates gene expression of various adipokines in 3T3-L1 adipocytes. Exposure to 100-500microM H(2)O(2) for 10min, as well as exposure to 5-25mU/ml glucose oxidase for 18h, similarly decreased adiponectin, leptin, and resistin mRNAs, and increased plasminogen activator inhibitor-1 mRNA. Secretion levels of adipokines were also changed by oxidative stress in parallel with mRNA expression levels. Although a peak increase in plasminogen activator inhibitor-1 mRNA was achieved between 4 and 8h after exposure to H(2)O(2) for 10min, significant decreases in adiponectin and resistin mRNA were observed after 16h, while leptin mRNA was decreased earlier. Our results suggest that oxidative stress, even of short duration, has a significant impact on the regulation of various adipokine gene expressions favoring atherosclerosis.

Induction of PAI-1 expression by tumor necrosis factor alpha in endothelial cells is mediated by its responsive element located in the 4G/5G site

Plasminogen activator inhibitor type 1 (PAI-1) is induced by many proinflammatory and pro-oxidant factors. Among them, tumor necrosis factor alpha (TNFalpha), a pivotal early mediator that regulates and amplifies the development of inflammation, is one of the strongest PAI-1 synthesis activators. Location of the TNFalpha response element in the PAI-1 promoter is still ambiguous. In this study, we attempted to evaluate the significance of the element located in the 4G/5G site of the PAI-1 promoter in the TNFalpha stimulation of PAI-1 expression in endothelial cells. PAI-1 expression was monitored at: (a) the level of mRNA using real-time PCR, (b) PAI-1 gene transcription by transfection reporter assays, and (c) protein synthesis using the enzyme immunoassay. NF-kappaB activity was monitored using the electrophoretic mobility shift assay. Its activity was modified by either antisense oligonucleotides or transfection of endothelial cells with the wild-type or mutated IkappaBalpha. We have shown that TNFalpha-induced expression and gene transcription of PAI-1 involves a regulatory region present in segment -664/-680 of the PAI-1 promoter. This reaction involves the TNFalpha-induced generation of superoxide leading to activation of NF-kappaB, and can be abolished by antioxidants and by overexpression of a super-suppressor phosphorylation-resistant IkappaBalpha. Stimulation of PAI-1 under these conditions involves the motif of the PAI-1 promoter adjacent to the 4G/5G site, which can directly interact with NF-kappaB. We show that activation of PAI-1 gene by TNFalpha and reactive oxygen species is mediated by interaction of NF-kappaB with the cis-acting element located in the -675 4G/5G insertion/deletion in the PAI-1 promoter.

Radiation and transforming growth factor-beta cooperate in transcriptional activation of the profibrotic plasminogen activator inhibitor-1 gene

Radiation-induced fibrosis is an important side effect in the treatment of cancer. Profibrotic proteins, such as plasminogen activator inhibitor-1 (PAI-1), transforming growth factor-beta (TGF-beta), and tissue type inhibitor of metalloproteinases-1 (Timp-1), are thought to play major roles in the development of fibrosis via the modulation of extracellular matrix integrity. We did a detailed analysis of transcriptional activation of these profibrotic genes by radiation and TGF-beta. Irradiation of HepG2 cells led to a high increase in PAI-1 mRNA levels and a mild increase in Timp-1 mRNA levels. In contrast, TGF-beta1 and Smad7 were not increased. Radiation and TGF-beta showed strong cooperative effects in transcription of the PAI-1 gene. The TGF-beta1 gene showed a mild cooperative activation, whereas Timp-1 and Smad7 were not cooperatively activated by radiation and TGF-beta. Analysis using the proximal 800 bp of the human PAI-1 promoter revealed a dose-dependent increase of PAI-1 levels between 2 and 32 Gy gamma-rays that was independent of latent TGF-beta activation. Subsequent site-directed mutagenesis of the PAI-1 promoter revealed that mutation of a p53-binding element abolished radiation-induced PAI-1 transcription. In line with this, PAI-1 was not activated in p53-null Hep3B cells, indicating that p53 underlies the radiation-induced PAI-1 activation and the cooperativity with the TGF-beta/Smad pathway. Together, these data show that radiation and TGF-beta activate PAI-1 via partially nonoverlapping signaling cascades that in concert synergize on PAI-1 transcription. This may play a role in patient-to-patient variations in susceptibility toward fibrosis after radiotherapy.

Peroxisome proliferator-activated receptor gamma as a drug target in the pathogenesis of insulin resistance

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the nuclear hormone receptor superfamily. The activation of PPAR-gamma, an isotype of PPARs, can either increase or decrease the transcription of target genes. The genes controlled by this form of PPAR have been shown to encode proteins or peptides that participate in the pathogenesis of insulin resistance. Insulin resistance is defined as a state of reduced responsiveness to normal circulating concentrations of insulin and it often co-exists with central obesity, hypertension, dyslipidemia, and atherosclerosis. There is substantial evidence that links obesity with insulin resistance and type-2 diabetes. The early phase of obesity-related insulin resistance has 2 components: (a) interruption of lipid homeostasis leading to the increased plasma concentration of fatty acids that is normally suppressed by the activation of PPAR-gamma, and (b) activation of factors such as cytokines depressed by PPAR-gamma that cause insulin resistance. Therefore, it is logical to suggest that activation of PPAR-gamma may partially reverse the state of insulin resistance. Evidently, activation of the nuclear receptor, PPAR-gamma, by thiazolidinediones has been reported to ameliorate insulin resistance. Although hepatotoxity and possibility to induce congestive heart failure (CHF) limit the widely use of thiazolodinediones, they are still powerful weapon to fight against insulin resistance and type-2 diabetes if use properly. This article reviews the physiology of PPAR-gamma and insulin-signaling transduction, the pathogenesis of insulin resistance in obesity-related type-2 diabetes, the pharmacological role of PPAR-gamma in insulin resistance, and additional effects of thiazolidinediones.

Thiazolidinediones inhibit TNFalpha induction of PAI-1 independent of PPARgamma activation

Increased plasminogen activator inhibitor type 1 (PAI-1) levels are observed in endothelial cells stimulated by tumour necrosis factor alpha (TNFalpha). Thiazolidinediones (TZDs) may inhibit elevated endothelial cell PAI-1 accounting, in part, for the putative atheroprotective effects of TZDs. In an endothelial cell line, Rosiglitazone (RG) and Pioglitazone (PG) inhibited induction of PAI-1 by TNFalpha. The specific peroxisome proliferator-activated receptor gamma (PPARgamma) inhibitor, SR-202, failed to modulate this effect. RG also inhibited the effect of TNFalpha on a reporter gene construct harbouring the proximal PAI-1 promoter and PAI-1 mRNA in cells co-transfected with a dominant-negative PPARgamma construct. RG and PG attenuated TNFalpha-mediated induction of trans-acting factor(s) Nur77/Nurr1 and binding of nuclear proteins (NP) to the cis-acting element (NBRE). SR-202 failed to modulate these effects. The observations suggest TZDs inhibit TNFalpha-mediated PAI-1 induction independent of inducible PPARgamma activation and this may involve in the modulation of Nur77/Nurr1 expression and NP binding to the PAI-1 NBRE.

Signalling pathways regulating the invasive differentiation of human trophoblasts: a review

The invasive differentiation pathway of trophoblasts is an indispensable physiological process of early human placental development. Formation of anchoring villi, proliferation of cell columns and invasion of extravillous cytotrophoblasts into maternal decidual stroma and vessels induce vascular changes ensuring an adequate blood supply to the growing fetus. Extravillous trophoblast differentiation is regulated by numerous growth factors as well as by extracellular matrix proteins and adhesion molecules expressed at the fetal-maternal interface. These regulatory molecules control cell invasion by modulating activities of matrix-degrading protease systems and ECM adhesion. The differentiation process involves numerous signalling cascades/proteins such as the GTPases RhoA, the protein kinases ROCK, ERK1, ERK2, FAK, PI3K, Akt/protein kinase B and mTOR as well as TGF-beta-dependent SMAD factors. While an increasing number of signalling pathways regulating trophoblast differentiation are being unravelled, downstream effectors such as executing transcription factors remain largely elusive. Here, we summarise our current knowledge on signal transduction cascades regulating invasive trophoblast differentiation. We will focus on cell model systems which are used to study the particular differentiation process and discuss signalling pathways which regulate trophoblast proliferation and motility.

PAI-1 and atherothrombosis

Plasminogen activator inhibitor-1 (PAI-1) is the major physiologic inhibitor of tissue-type plasminogen activator in plasma, and is elevated in a variety of clinical situations that are associated with increased risk of ischemic cardiovascular events. Recent insights into the biology of PAI-1 suggest that it is more than just an innocent bystander in the pathogenesis of ischemic heart disease. Elevated PAI-1 levels appear to increase the risk of atherothrombotic events and may also promote the progression of vascular disease. The development and testing of specific PAI-1 antagonists will enable basic and clinical investigators the opportunity to test the hypothesis that vascular PAI-1 excess promotes the development of intravascular thrombosis and atherosclerosis.

Molecular mechanisms of tumor necrosis factor-alpha-mediated plasminogen activator inhibitor-1 expression in adipocytes

Increased expression of plasminogen activator inhibitor -1 (PAI-1) in adipose tissues is thought to contribute to both the cardiovascular and metabolic complications associated with obesity. Tumor necrosis factor alpha (TNF-alpha) is chronically elevated in adipose tissues of obese rodents and humans and has been directly implicated to induce PAI-1 in adipocytes. In this study, we used 3T3-L1 adipocytes to examine the mechanism by which TNF-alpha up-regulates PAI-1 in the adipocyte. Acute (3 h) and chronic (24 h) exposure of 3T3-L1 adipocytes to TNF-alpha induces PAI-1 mRNA by increasing the rate of transcription of the PAI-1 gene, and de novo protein synthesis is not required for this process. Although the p44/42 and PKC signaling pathways appear to be significant in the induction of PAI-1 mRNA in response to acute treatment with TNF-alpha, the more dramatic induction of PAI-1 mRNA observed in response to chronic exposure of adipocytes to TNF-alpha was mediated by these and additional signaling molecules, including p38, PI3-kinase, tyrosine kinases, and the transcription factor NF-kappaB. Moreover, the dramatic increase in PAI-1 observed after chronic exposure of adipocytes to TNF-alpha was accompanied by increased metabolic insulin resistance. Finally, we demonstrate that the PKC pathway is also central for PAI-1 induction in response to insulin and transforming growth factor-beta (TGF-beta), two additional molecules which are elevated in obesity and shown to directly induce PAI-1 in the adipocyte. The understanding of the mechanism of regulating PAI-1 expression in the adipocytes at the molecular level provides new insight to help identify novel targets in fighting the pathological complications of obesity.

In vivo and in vitro analysis of the human tissue-type plasminogen activator gene promoter in neuroblastomal cell lines: evidence for a functional upstream kappaB element

Besides its well-established role in wound healing and fibrinolysis, tissue-type plasminogen activator (t-PA) has been shown to contribute to cognitive processes and memory formation within the central nervous system, and to promote glutamate receptor-mediated excitotoxicity. The t-PA gene is expressed and regulated in neuronal cells but the regulatory transcriptional processes directing this expression are still poorly characterized. We have used DNase I-hypersensitivity mapping and in vivo foot printing to identify putative regulatory elements and transcription factor binding sites in two human neuroblastomal (KELLY and SK-N-SH) and one human glioblastomal (SNB-19) cell lines. Hypersensitive sites were found in the proximal promoter region of all cell lines, and within the first exon for KELLY and SNB-19 cells. Mapping of methylation-protected residues in vivo detected a cluster of protected residues corresponding to a cAMP response element (CRE) and Sp1 sites in the proximal promoter previously shown to be essential for basal expression in other cell types. Protected residues were also found at other sites, notably a kappaB element at position bp -3081 to -3072 that was partly protected in KELLY and SNB-19 cells. Analysis of transfected reporter constructs in KELLY and SNB-19 cells confirmed that this particular element is functionally significant in the transactivation of the t-PA promoter in both cell types. This study defines, by in vivo and in vitro methods, a previously undescribed kappaB site in the t-PA gene promoter that influences t-PA expression in neuronal cells.

Lysophosphatidylcholine induces tPA gene expression through CRE-dependent mechanism

Lysophosphatidylcholine (lysoPC) is implicated in the development of atherosclerosis and certain autoimmune diseases, and is reported to induce tissue-type plasminogen activator (tPA) at the protein level in endothelial cells. This study was designed to investigate the effect of lysoPC on tPA gene expression and the underlying molecular mechanisms in cultured endothelial cells. LysoPC transiently induced the mRNA expression of tPA in endothelial cells. LysoPC also induced the mRNA expression of urokinase-type plasminogen activator (uPA), uPA receptor, and plasminogen activator inhibitor-1, but the kinetics were different from that of tPA. Promoter analysis revealed that the cyclic AMP-responsive element of the tPA gene (tPACRE) is required for lysoPC-induced tPA expression. Furthermore, an electrophoresis mobility shift assay showed that lysoPC increased the binding activity of CRE binding protein to tPACRE. These results indicated that lysoPC transcriptionally upregulated the gene expression of tPA in endothelial cells, at least in part, via tPACRE activation.

Smad6s regulates plasminogen activator inhibitor-1 through a protein kinase C-beta-dependent up-regulation of transforming growth factor-beta

Plasminogen activator inhibitor-1 (PAI-1) is a serpin class protease inhibitor that plays a central role in the regulation of vascular function and tissue remodeling by modulating thrombosis, inflammation, and the extracellular matrix. A central mediator controlling PAI-1 is transforming growth factor-beta (TGF-beta), which induces its expression and promotes fibrosis. We have found that a unique member of the Smad family of signal transduction molecules, Smad6s, modulates the expression of PAI-1. Overexpression of Smad6s in endothelial cells increases promoter activity and PAI-1 secretion, and an antisense to Smad6s suppresses the induction of PAI-1 by TGF-beta. The effect of Smad6s on the PAI-1 promoter appeared to be the result of increase binding of the forkhead winged helix factor FoxD1 to a TGF-beta-responsive element. Furthermore, the effect of Smad6s on PAI-1 up-regulation and on FoxD1 binding was found to result from up-regulation of TGF-beta and could be inhibited by the blocking TGF-beta signaling with Smad7. The ability of Smad6s to regulate the TGF-beta promoter and subsequent PAI-1 induction was suppressed by a selective protein kinase C-beta (PKC-beta) inhibitor. Consistent with the in vitro data, we found that increased Smad6s in diseased vessels correlated with increased TGF-beta and PAI-1 levels. Overall, our results demonstrate that the level of Smad6s can alter the level of TGF-beta and the subsequent induction of PAI-1 via a FoxD1 transcription site. Furthermore, our data suggest that this process, which is up-regulated in diseased vessels, can be modulated by the inhibition of PKC-beta.