Cyclic AMP-independent ATF family members interact with NF-kappa B and function in the activation of the E-selectin promoter in response to cytokines

Annexin A3 Represses Endothelial Permeability and Inflammation During Sepsis via Actin Cytoskeleton Modulation

Increased endothelial permeability and a dysregulated inflammatory response play key roles in organ damage in sepsis. The role of annexin A3 (ANXA3) in regulating endothelial permeability and inflammation during sepsis is explored using ANXA3 knockout mice and primary human umbilical vein endothelial cells (HUVECs). The absence of ANXA3 exacerbated sepsis outcomes, including increased mortality, lung injury, leukocyte infiltration, and vascular permeability. ANXA3 is highly expressed in endothelial cells and its loss results in the formation of cytoskeletal stress fibers and a decrease in the expression of the junction proteins zonula occludens (Zo)-1, vascular endothelial (VE)-cadherin, and claudin 5, leading to increase permeability. ANXA3 knockdown also upregulates E-selectin (CD62E) expression through the phosphorylation of activating transcription factor 2 (ATF2), which increases monocyte adhesion in HUVECs after LPS stimulation. Inhibiting actin polymerization reverse these effects. Thus, ANXA3 stabilizes the actin cytoskeleton, playing a protective role in endothelial dysfunction during sepsis.

Chromatin mapping and single-cell immune profiling define the temporal dynamics of ibrutinib response in CLL

The Bruton tyrosine kinase (BTK) inhibitor ibrutinib provides effective treatment for patients with chronic lymphocytic leukemia (CLL), despite extensive heterogeneity in this disease. To define the underlining regulatory dynamics, we analyze high-resolution time courses of ibrutinib treatment in patients with CLL, combining immune-phenotyping, single-cell transcriptome profiling, and chromatin mapping. We identify a consistent regulatory program starting with a sharp decrease of NF-κB binding in CLL cells, which is followed by reduced activity of lineage-defining transcription factors, erosion of CLL cell identity, and acquisition of a quiescence-like gene signature. We observe patient-to-patient variation in the speed of execution of this program, which we exploit to predict patient-specific dynamics in the response to ibrutinib based on the pre-treatment patient samples. In aggregate, our study describes time-dependent cellular, molecular, and regulatory effects for therapeutic inhibition of B cell receptor signaling in CLL, and it establishes a broadly applicable method for epigenome/transcriptome-based treatment monitoring.

Ibrutinib, a Bruton tyrosine kinase inhibitor, provides effective treatment for chronic lymphocytic leukemia (CLL). Here, the authors describe time-dependent molecular changes to malignant cells and to the immune system in patients undergoing ibrutinib therapy, with can be used for therapy monitoring.

Carnosol suppresses interleukin-6 production in mouse lungs injured by ischemia–reperfusion operation and in RAW264.7 macrophages treated with lipopolysaccharide

Carnosol is a naturally occurring herbal compound, known for its antioxidative properties. We previously found that carnosol protected mouse lungs from ischemia–reperfusion injury in ex vivo cultures. To elucidate the molecular mechanisms underpinning carnosol-mediated lung protection, we analyzed modes of interleukin-6 (IL-6) gene expression, which is associated with lung ischemia–reperfusion injury. Microarray analysis of mouse lungs suggested that IL-6 mRNA levels were elevated in the mouse lungs subjected to clamp-reperfusion, which was associated with elevated levels of other inflammatory modulators, such as activating transcription factor 3 (ATF3). Carnosol pretreatment lowered the IL-6 protein levels in mouse lung homogenates prepared after the clamp-reperfusion. On the other hand, the ATF3 gene expression was negatively correlated with that of IL-6 in RAW264.7 cells. IL-6 mRNA levels and gene promoter activities were suppressed by carnosol in RAW264.7 cells, but rescued by ATF3 knockdown. When RAW264.7 cells were subjected to hypoxia–reoxygenation, carnosol treatment lowered oxygen consumption after reoxygenation, which was coupled with a correlation with a transient production of mitochondrial reactive oxygen species and following ATF3 gene expression. These results suggest that carnosol treatment could be a new strategy for protecting lungs from ischemia–reperfusion injury by modulating the ATF3–IL-6 axis.

Associations of estradiol levels and genetic polymorphisms of inflammatory genes with the risk of ischemic stroke

Background

Estrogen plays an important role as an anti-inflammatory and neuroprotective agent in ischemic stroke. In this study, we analyzed the effect of a polygenic risk score (PRS) constructed using inflammatory genes and estradiol levels on the risk of ischemic stroke.

Methods

This case-control study was conducted with 624 ischemic stroke patients and 624 age- and gender-matched controls. The PRS estimated the polygenic contribution of inflammatory genes from ischemic stroke susceptibility loci. Estradiol levels were measured using a radioimmunoassay. High and low estradiol levels were defined according to the log-transformed median estradiol levels in female and male controls.

Results

Subjects in the fourth quartile of the PRS had a significant 1.57-fold risk of ischemic stroke (95% confidence interval [CI], 1.12 ~ 2.19), after adjusting for covariates compared to individuals in the lowest quartile. Compared to individuals with high estradiol levels and a low PRS as the reference group, those exposed to low estradiol levels and a high PRS had an increased risk of ischemic stroke (odds ratio, 3.35; 95% CI, 1.79 ~ 6.28). Similar results were also observed in males when the analysis was stratified by gender.

Conclusions

Our data suggest that the PRS can be useful in evaluating a high risk of ischemic stroke among patients, especially those exposed to low estradiol levels.

TNF-α enhancement of CD62E mediates adhesion of non-small cell lung cancer cells to brain endothelium via CD15 in lung-brain metastasis

BACKGROUND

CD15, which is overexpressed on various cancers, has been reported as a cell adhesion molecule that plays a key role in non-CNS metastasis. However, the role of CD15 in brain metastasis is largely unexplored. This study provides a better understanding of CD15/CD62E interaction, enhanced by tumor necrosis factor-α (TNF-α), and its correlation with brain metastasis in non-small cell lung cancer (NSCLC).

METHODS

CD15 and E-selectin (CD62E) expression was demonstrated in both human primary and metastatic NSCLC cells using flow cytometry, immunofluorescence, and Western blotting. The role of CD15 was investigated using an adhesion assay under static and physiological flow live-cell conditions. Human tissue sections were examined using immunohistochemistry.

RESULTS

CD15, which was weakly expressed on hCMEC/D3 human brain endothelial cells, was expressed at high levels on metastatic NSCLC cells (NCI-H1299, SEBTA-001, and SEBTA-005) and at lower levels on primary NSCLC (COR-L105 and A549) cells (P < .001). The highest expression of CD62E was observed on hCMEC/D3 cells activated with TNF-α, with lower levels on metastatic NSCLC cells followed by primary NSCLC cells. Metastatic NSCLC cells adhered most strongly to hCMEC/D3 compared with primary NSCLC cells. CD15 immunoblocking decreased cancer cell adhesion to brain endothelium under static and shear stress conditions (P < .0001), confirming a correlation between CD15 and cerebral metastasis. Both CD15 and CD62E expression were detected in lung metastatic brain biopsies.

CONCLUSION

This study enhances the understanding of cancer cell-brain endothelial adhesion and confirms that CD15 plays a crucial role in adhesion in concert with TNF-α activation of its binding partner, CD62E.

Crucial Role of the Aryl Hydrocarbon Receptor (AhR) in Indoxyl Sulfate-Induced Vascular Inflammation

AIM

The aryl hydrocarbon receptor (AhR), a ligand-inducible transcription factor mediating toxic effects of dioxins and uremic toxins, has recently emerged as a pathophysiological regulator of immune-inflammatory conditions. Indoxyl sulfate, a uremic toxin, is associated with cardiovascular disease in patients with chronic kidney disease and has been shown to be a ligand for AhR. The aim of this study was to investigate the potential role of AhR in indoxyl sulfate-induced leukocyte-endothelial interactions.

METHODS

Endothelial cell-specific AhR knockout (eAhR KO) mice were produced by crossing AhR floxed mice with Tie2 Cre mice. Indoxyl sulfate was administered for 2 weeks, followed by injection of TNF-α. Leukocyte recruitment to the femoral artery was assessed by intravital microscopy. Vascular endothelial cells were transfected with siRNA specific to AhR (siAhR) and treated with indoxyl sulfate, followed by stimulation with TNF-α.

RESULTS

Indoxyl sulfate dramatically enhanced TNF-α-induced leukocyte recruitment to the vascular wall in control animals but not in eAhR KO mice. In endothelial cells, siAhR significantly reduced indoxyl sulfate-enhanced leukocyte adhesion as well as E-selectin expression, whereas the activation of JNK and nuclear factor-κB was not affected. A luciferase assay revealed that the region between －153 and －146 bps in the E-selectin promoter was responsible for indoxyl sulfate activity via AhR. Mutational analysis of this region revealed that activator protein-1 (AP-1) is responsible for indoxyl sulfate-triggered E-selectin expression via AhR.

CONCLUSION

AhR mediates indoxyl sulfate-enhanced leukocyte-endothelial interactions through AP-1 transcriptional activity, which may constitute a new mechanism of vascular inflammation in patients with renal disease.

Induction of activating transcription factor 3 limits survival following infarct-induced heart failure in mice

Numerous fibrotic and inflammatory changes occur in the failing heart. Recent evidence indicates that certain transcription factors, such as activating transcription factor 3 (ATF3), are activated during heart failure. Because ATF3 may be upregulated in the failing heart and affect inflammation, we focused on the potential role of ATF3 on postinfarct heart failure. We subjected anesthetized, wild-type mice to nonreperfused myocardial infarction and observed a significant induction in ATF3 expression and nuclear translocation. To test whether the induction of ATF3 affected the severity of heart failure, we subjected wild-type and ATF3-null mice to nonreperfused infarct-induced heart failure. There were no differences in cardiac function between the two genotypes, except at the 2-wk time point; however, ATF3-null mice survived the heart failure protocol at a significantly higher rate than the wild-type mice. Similar to the slight favorable improvements in chamber dimensions at 2 wk, we also observed greater cardiomyocyte hypertrophy and more fibrosis in the noninfarcted regions of the ATF3-null hearts compared with the wild-type. Nevertheless, there were no significant group differences at 4 wk. Furthermore, we found no significant differences in markers of inflammation between the wild-type and ATF3-null hearts. Our data suggest that ATF3 suppresses fibrosis early but not late during infarct-induced heart failure. Although ATF3 deficiency was associated with more fibrosis, this did not occur at the expense of survival, which was higher in the ATF3-null mice. Overall, ATF3 may serve a largely maladaptive role during heart failure.

Deoxycholic acid inhibited proliferation and induced apoptosis and necrosis by regulating the activity of transcription factors in rat pancreatic acinar cell line AR42J

The objective of this study is to investigate the effect of deoxycholic acid (DCA) on rat pancreatic acinar cell line AR42J and the functional mechanisms of DCA on AR42J cells. AR42J cells were treated with various concentrations of DCA for 24 h and also treated with 0.4 mmol/L DCA for multiple times, and then, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to detect the AR42J cell survival rate. Flow cytometric was used to detect the cell apoptosis and necrosis in AR42J cells treated with 0.4 mmol/L and 0.8 mmol/L DCA. The cells treated with phosphate buffer saline (PBS) were served as control. In addition, the DNA-binding activity assays of transcription factors (TFs) in nuclear proteins of cells treated with DCA were determined using Panomics Procarta Transcription Factor Assay Kit. The relative survival rates were markedly decreased (P < 0.05) in a dose- and time-dependent manner. Compared with control group, the cell apoptosis and necrosis ratio were both significantly elevated in 0.4 mmol/L DCA and 0.8 mmol/L DCA groups (P < 0.01). A significant increase (P < 0.05) in the activity of transcription factor 2 (ATF2), interferon-stimulated response element (ISRE), NKX-2.5, androgen receptor (AR), p53, and hypoxia-inducible factor-1 (HIF-1) was observed, and the activity of peroxisome proliferator-activated receptor (PPAR), activator protein 1 (AP1), and E2F1 was reduced (P < 0.05). In conclusion, DCA inhibited proliferation and induced apoptosis and necrosis in AR42J cells. The expression changes of related genes regulated by TFs might be the molecular mechanism of AR42J cell injury.

Dynasore enhances the formation of mitochondrial antiviral signalling aggregates and endocytosis-independent NF-κB activation

BACKGROUND AND PURPOSE

Dynasore has been used extensively as an inhibitor of clathrin-mediated endocytosis. While studying the role of endocytosis in LPS-induced signalling events, we discovered that dynasore itself induced activation of NF-κB, independently of its effects on endocytosis and without involving the Toll-like receptor 4 signalling pathways. The purpose of this study was to characterize this novel effect and to explore the underlying mechanism of action.

EXPERIMENTAL APPROACH

We utilized gel electrophoresis, microscopy, gene knockdown and luciferase-based promoter activity to evaluate the effect of dynasore on cell signalling pathways and to delineate the mechanisms involved in its effects,

KEY RESULTS

Dynasore activated the NF-κB and IFN-β pathways by activating mitochondrial antiviral signalling protein (MAVS). We showed that MAVS is activated by NOX/Rac and forms high molecular weight aggregates, similar to that observed in response to viral infection. We also demonstrated that dynasore-induced activation of JNK occurs downstream of MAVS and is required for activation of NF-κB and IFN-β.

CONCLUSION AND IMPLICATIONS

These findings demonstrate a novel effect of dynasore on cell signalling. We describe a novel Rac1-, ROS- and MAVS-mediated signalling cascade through which dynasore dramatically activates NF-κB, mimicking the viral induction of this key inflammatory signalling pathway. Our results call attention to the need for a broader interpretation of results when dynasore is used in its traditional fashion as an inhibitor of clathrin-mediated endocytosis. These results suggest the intriguing possibility that dynasore or one of its analogues might be of value as an antiviral therapeutic strategy or vaccine adjuvant.

Cell density impacts epigenetic regulation of cytokine-induced E-selectin gene expression in vascular endothelium

Growing evidence suggests that the phenotype of endothelial cells during angiogenesis differs from that of quiescent endothelial cells, although little is known regarding the difference in the susceptibility to inflammation between both the conditions. Here, we assessed the inflammatory response in sparse and confluent endothelial cell monolayers. To obtain sparse and confluent monolayers, human umbilical vein endothelial cells were seeded at a density of 7.3 × 10(3) cells/cm(2) and 29.2 × 10(3) cells/cm(2), respectively, followed by culturing for 36 h and stimulation with tumor necrosis factor α. The levels of tumor necrosis factor α-induced E-selectin protein and mRNA expression were higher in the confluent monolayer than in the sparse monolayer. The phosphorylation of c-jun N-terminal kinase and p38 mitogen-activated protein kinase or nuclear factor-κB activation was not involved in this phenomenon. A chromatin immunoprecipitation assay of the E-selectin promoter using an anti-acetyl-histone H3 antibody showed that the E-selectin promoter was highly and specifically acetylated in the confluent monolayer after tumor necrosis factor α activation. Furthermore, chromatin accessibility real-time PCR showed that the chromatin accessibility at the E-selectin promoter was higher in the confluent monolayer than in the sparse monolayer. Our data suggest that the inflammatory response may change during blood vessel maturation via epigenetic mechanisms that affect the accessibility of chromatin.

Testosterone: a vascular hormone in health and disease

Coronary heart disease is a leading cause of premature death in men. Epidemiological studies have shown a high prevalence of low serum testosterone levels in men with cardiovascular disease (CVD). Furthermore, a low testosterone level is associated in some but not in all observational studies with an increase in cardiovascular events and mortality. Testosterone has beneficial effects on several cardiovascular risk factors, which include cholesterol, endothelial dysfunction and inflammation: key mediators of atherosclerosis. A bidirectional relationship between low endogenous testosterone levels and concurrent illness complicates attempts to validate causality in this association and potential mechanistic actions are complex. Testosterone is a vasoactive hormone that predominantly has vasodilatory actions on several vascular beds, although some studies have reported conflicting effects. In clinical studies, acute and chronic testosterone administration increases coronary artery diameter and flow, improves cardiac ischaemia and symptoms in men with chronic stable angina and reduces peripheral vascular resistance in chronic heart failure. Although the mechanism of the action of testosterone on vascular tone in vivo is not understood, laboratory research has found that testosterone is an L-calcium channel blocker and induces potassium channel activation in vascular smooth muscle cells. Animal studies have consistently demonstrated that testosterone is atheroprotective, whereas testosterone deficiency promotes the early stages of atherogenesis. The translational effects of testosterone between in vitro animal and human studies, some of which have conflicting effects, will be discussed in this review. We review the evidence for a role of testosterone in vascular health, its therapeutic potential and safety in hypogonadal men with CVD, and some of the possible underlying mechanisms.

Oxidative stress and MAPK involved into ATF2 expression in immortalized human urothelial cells treated by arsenic

ATF2 is a subfamily member of AP-1 and has an important role in cellular stress responses. ATF2 has been implicated in a transcriptional response leading to cell migration and malignant tumor progression. However, little is known about the effect of arsenic on expression of ATF2 and regulatory pathways in human urothelial cells. In this study, ATF2 expression was measured in NaAsO(2)-treated human uroepithelial cell line (SV-HUC-1) with 1, 2, 4, 8 and 10 μM concentrations in order to provide some basis data for the study on mechanism of bladder cancer induced by arsenic. We found that ATF2 expression levels at 2, 4, 8 and 10 μM arsenic-treated cells were significantly higher than those of control cells, and the strongest expression occurred in 4 μM NaAsO(2)-treated cells. Antioxidants (melatonin) and JNK or p38 inhibitors decreased significantly arsenic-induced ATF2 expression. Taken together, these data indicated that the increasing of ATF2 expression is mediated via oxidative stress induced by arsenic in SV-HUC-1 cells, and JNK or p38 rather than ERK is responsible for arsenic-induced ATF2 expression. ROS were also involved in arsenic induced the activation of JNK and p38 MAPK signaling pathway.

Kaiso directs the transcriptional corepressor MTG16 to the Kaiso binding site in target promoters

Myeloid translocation genes (MTGs) are transcriptional corepressors originally identified in acute myelogenous leukemia that have recently been linked to epithelial malignancy with non-synonymous mutations identified in both MTG8 and MTG16 in colon, breast, and lung carcinoma in addition to functioning as negative regulators of WNT and Notch signaling. A yeast two-hybrid approach was used to discover novel MTG binding partners. This screen identified the Zinc fingers, C2H2 and BTB domain containing (ZBTB) family members ZBTB4 and ZBTB38 as MTG16 interacting proteins. ZBTB4 is downregulated in breast cancer and modulates p53 responses. Because ZBTB33 (Kaiso), like MTG16, modulates Wnt signaling at the level of TCF4, and its deletion suppresses intestinal tumorigenesis in the Apc^Min mouse, we determined that Kaiso also interacted with MTG16 to modulate transcription. The zinc finger domains of Kaiso as well as ZBTB4 and ZBTB38 bound MTG16 and the association with Kaiso was confirmed using co-immunoprecipitation. MTG family members were required to efficiently repress both a heterologous reporter construct containing Kaiso binding sites (4×KBS) and the known Kaiso target, Matrix metalloproteinase-7 (MMP-7/Matrilysin). Moreover, chromatin immunoprecipitation studies placed MTG16 in a complex occupying the Kaiso binding site on the MMP-7 promoter. The presence of MTG16 in this complex, and its contributions to transcriptional repression both required Kaiso binding to its binding site on DNA, establishing MTG16-Kaiso binding as functionally relevant in Kaiso-dependent transcriptional repression. Examination of a large multi-stage CRC expression array dataset revealed patterns of Kaiso, MTG16, and MMP-7 expression supporting the hypothesis that loss of either Kaiso or MTG16 can de-regulate a target promoter such as that of MMP-7. These findings provide new insights into the mechanisms of transcriptional control by ZBTB family members and broaden the scope of co-repressor functions for the MTG family, suggesting coordinate regulation of transcription by Kaiso/MTG complexes in cancer.

Transcriptional regulation of mouse neuroglobin gene by cyclic AMP responsive element binding protein (CREB) in N2a cells

Neuroglobin (Ngb) has been demonstrated to be a novel neuroprotective protein that protects against hypoxia/ischemia and oxidative stress-induced injury in the nervous system. However, the regulation mechanisms of Ngb gene expression under both normal resting and stress conditions have not been fully elucidated. The cyclic AMP response element binding protein (CREB) is a key transcription factor that regulates a variety of pro-survival genes, but its role in regulating the neuroprotective gene Ngb has not been studied. In this study we investigated the transcriptional regulation of mouse Ngb gene by CREB in mouse neuroblastoma cell line N2a. Our results showed that CREB knockdown decreased Ngb gene expression, and overexpression of the wild-type CREB, but not the mutant CREB, significantly increased Ngb gene expression in N2a cells. Moreover, a cAMP response element (CRE) site located at -854 in the promoter region of mouse Ngb gene was found to be responsible for both basal and CREB-induced Ngb promoter activity. Using chromatin immunopreciptation (ChIP) assays, we found that CREB could bind to the Ngb promoter region spanning from -1016 to -793 that harbors the CRE site. Taken together, our results suggested that transcription factor CREB participates in the transcriptional regulation of mouse Ngb gene.

Rapidly induced gene networks following induction of long-term potentiation at perforant path synapses in vivo

The canonical view of the maintenance of long-term potentiation (LTP), a widely accepted experimental model for memory processes, is that new gene transcription contributes to its consolidation; however, the gene networks involved are unknown. To address this issue, we have used high-density Rat 230.2 Affymetrix arrays to establish a set of genes induced 20-min post-LTP, and using Ingenuity Pathway network analysis tools we have investigated how these early responding genes are interrelated. This analysis identified LTP-induced regulatory networks in which the transcription factors (TFs) nuclear factor-KB and serum response factor, which, to date, have not been widely recognized as coordinating the early gene response, play a key role alongside the more well-known TFs cyclic AMP response element-binding protein, and early growth response 1. Analysis of gene-regulatory promoter sites and chromosomal locations of the genes within the dataset reinforced the importance of these molecules in the early gene response and predicted that the coordinated action might arise from gene clustering on particular chromosomes. We have also identified a transcription-based response that affects mitogen-activated protein kinase signaling pathways and protein synthesis during the stabilization of the LTP response. Furthermore, evidence from biological function, networks, and regulatory analyses showed convergence on genes related to development, proliferation, and neurogenesis, suggesting that these functions are regulated early following LTP induction. This raises the interesting possibility that LTP-related gene expression plays a role in both synaptic reorganization and neurogenesis.

Effect of obesity on the association between ATF3 gene haplotypes and C-reactive protein level in Taiwanese

OBJECTIVE

ATF3 has traditionally been related to various inflammatory processes. Our aim was to test the statistical association between variations in the ATF3 gene and levels of nine serum inflammatory markers, including C reactive protein (CRP), in a Taiwanese population using interaction analysis.

METHODS

A sample population of 604 Taiwanese subjects was enrolled. Five tagging single nucleotide polymorphisms of the ATF3 gene from the Han Chinese HapMap Database were selected and genotyped.

RESULTS

With or without adjustment for clinical covariates, ATF3 genotypes were found to be associated with CRP levels but not with other inflammatory marker levels. Minor alleles of 2 of the 5 ATF3 SNPs were associated with decreased CRP levels predominantly in non-obese subjects (Bonferoni P=0.018, and P=0.002 for rs11571530, and rs10475, respectively). Two haplotypes inferred from the 5 SNPs, GATTA and TACCA, were also associated with increased or decreased CRP levels, respectively, in non-obese subjects (Bonferoni P=0.012 and P=0.01, respectively) but not in obese subjects. Interaction analysis revealed interaction of obesity with an ATF3 genotype associated with a high CRP level (interaction P=0.006 for SNP rs10475). An effect of obesity on CRP level was also noted in haplotype interaction analysis (interaction P=0.019 for haplotype TACCA).

CONCLUSIONS

ATF3 polymorphisms are independently associated with CRP levels in Taiwanese subjects. Further, ATF3 genotypes/haplotypes interact with obesity to set CRP levels. These findings may have implications for the prediction of atherosclerotic disease.

Multistage carcinogenesis process as molecular targets in cancer chemoprevention by epicatechin-3-gallate

The consumption of green tea has long been associated with a reduced risk of cancer development. (-)-Epicatechin-3-gallate (ECG) or (-)-epigallocatechin-3-gallate (EGCG) are the major antioxidative polyphenolic compounds of green tea. They have been shown to exert growth-inhibitory potential of various cancer cells in culture and antitumor activity in vivo models. ECG or EGCG could interact with various molecules like proteins, transcription factors, and enzymes, which block multiple stages of carcinogenesis via regulating intracellular signaling transduction pathways. Moreover, ECG and EGCG possess pharmacological and physiological properties including induction of phase II enzymes, mediation of anti-inflammation response, regulation of cell proliferation and apoptosis effects and prevention of tumor angiogenesis, invasion and metastasis. Numerous review articles have been focused on EGCG, however none have been focused on ECG despite many studies supporting the cancer preventive potential of ECG. To develop ECG as an anticarcinogenic agent, more clear understanding of the cell signaling pathways and the molecular targets responsible for chemopreventive and chemotherapeutic effects are needed. This review summarizes recent research on the ECG-induced cellular signal transduction events which implicate in cancer management.

Characterization of contraction-inducible CXC chemokines and their roles in C2C12 myocytes

Physical exercise triggers the release of several cytokines/chemokines from working skeletal muscles, but the underlying mechanism(s) by which skeletal muscles decipher and respond to highly complex contractile stimuli remains largely unknown. In an effort to investigate the regulatory mechanisms of the expressions of two contraction-inducible CXC chemokines, CXCL1/KC and CXCL5/LIX, in contracting skeletal muscle cells, we took advantage of our in vitro exercise model using highly developed contractile C(2)C(12) myotubes, which acquire properties similar to those of in vivo skeletal muscle via manipulation of Ca(2+) transients with electric pulse stimulation (EPS). Production of these CXC chemokines was immediately augmented by EPS-evoked contractile activity in a manner dependent on the activities of JNK and NF-kappaB, but not p38, ERK1/2, or calcineurin. Intriguingly, exposure of myotubes to cyclic mechanical stretch also induced expression of these CXC chemokines; however, a much longer period of stimulation (approximately 12 h) was required, despite rapid JNK phosphorylation. We also demonstrate herein that CXCL1/KC and CXCL5/LIX have the ability to raise intracellular Ca(2+) concentrations via CXCR2-mediated activation of pertussis toxin-sensitive Galpha(i) proteins in C(2)C(12) myoblasts, an action at least partially responsible for their migration and differentiation. Although we revealed a possible negative feedback regulation of their own production in response to the contractile activity in differentiated myotubes, exogenous administration of these CXC chemokines did not acutely influence either insulin-induced Akt phosphorylation or GLUT4 translocation in C(2)C(12) myotubes. Taken together, these data shed light on the fundamental characteristics of contraction-inducible CXC chemokine production and their potential roles in skeletal muscle cells.

Glucocorticoids and the emerging importance of T cell subsets in steroid refractory diseases

Glucocorticoids remain the first-line treatment for a range of autoimmune and allergic diseases. However, 30% of patients fail to achieve disease control at tolerable systemic doses and continue to have an increased immune response with poor clinical outcome. This steroid refractory (SR) phenotype has previously been attributed to enhanced expression of inactive glucocorticoid receptor isoforms and cytokine-mediated suppression of glucocorticoid (GC) signaling, in particular by interleukin-2. These mechanisms are discussed, with emphasis on recent evidence for the role of the CD4(+)CD25(int) and GC-induced T regulatory cell subsets in perpetrating SR disease.

Overexpression of phosphorylated-ATF2 and STAT3 in cutaneous angiosarcoma and pyogenic granuloma

BACKGROUND

Activating transcription factor-2/Activator protein-1 (AP-1), Signal transducer and activator of transcription-3 and p53 are important regulators of cellular proliferation, apoptosis, differentiation in the pathogenesis of many human tumors, but the expression of phosphorylated (p)-activating transcription factor-2 (p-ATF2), phosphorylated (p)-signal transducer and activator of transcription-3 (p-STAT3) and p53 family (p63 and p73) has not been investigated in cutaneous angiosarcoma (CAS) and pyogenic granuloma (PG) so far.

OBJECTIVES

To investigate the expression of p-ATF2, p-STAT3 and p53 and its family in cutaneous vascular tumors (CAS and PG).

METHODS

Paraffin-embedded specimens of 14 CAS and 19 PG were subjected to immunohistochemical staining for p-ATF2, p-STAT3, p53, p63 and p73.

RESULTS

P-ATF2 was expressed in 13 out of 14 CAS and in all of 19 PG. P-STAT3 was expressed in all of 14 CAS and 19 PG. P53 was expressed in all of 14 CAS and 19 PG, while both p63 and p73 were negative in CAS and PG. The p-ATF2-, p-STAT3- and p53 expression (% positive cells) in CAS and PG were significantly higher than in normal dermal vessels, but none of these transcription factors distinguished malignant (CAS)- from benign (PG) vascular tumor.

CONCLUSIONS

The present study suggests that overexpression of p-ATF2, p-STAT3 and possibly p53, but not p63 or p73, may contribute to the tumorigenesis of cutaneous vascular tumors.

Protein O-N-acetylglucosaminylation modulates promoter activities of cyclic AMP response element and activator protein 1 and enhances E-selectin expression on HuH-7 human hepatoma cells

High glucose accelerates O-N-acetylglucosaminylation (O-GlcNAcylation) of proteins and causes diabetic complications. In the present study, we found that treatment of HuH-7 human hepatoma cells with high glucose or the protein O-N-acetylglucosaminidase (O-GlcNAcase) inhibitor O-(2-acetoamide-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc) increased the cell surface expression of E-selectin. A dual luciferase reporter assay indicated that high glucose and PUGNAc suppressed promoter activities of the cyclic AMP response element (CRE) and enhanced those of activator protein 1 (AP-1). Enhanced CRE promoter activities in HuH-7 cells treated with dibutyryl cAMP or co-transfected with a protein kinase A expression vector pFC-PKA that enhances the phosphorylation of CRE binding protein (CREB) were suppressed by PUGNAc. In contrast, PUGNAc further increased the enhanced AP-1 promoter activity in cells transfected with a mitogen-activated protein kinase kinase kinase expression vector pFC-MEKK that enhances c-Jun phosphorylation. Immuno-blotting using an anti-O-GlcNAc antibody revealed that high glucose and PUGNAc accelerated protein O-GlcNAcylation and that there were substantial differences in the O-GlcNAcylated proteins in the cytoplasmic and nuclear fractions. In addition, PUGNAc increased the nuclear import of O-GlcNAcylated CREB. These results suggest that protein O-GlcNAcylation modulates the promoter activities of E-selectin gene, suppression of CRE and enhancement of AP-1, and enhances E-selectin protein expression on hepatocytes.

Green tea catechin (-)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation

Epicatechin gallate (ECG) is the third major catechin component in green tea, but it shows strong biological activity in some aspects, including apoptosis, cell growth inhibition, and membrane transport system in various cells. We previously reported that ECG induces activating transcription factor 3 (ATF3), which is involved in pro-apoptosis in HCT-116 cells. In this report, we present a molecular mechanism by which ECG induces ATF3 expression at the transcriptional level. We found that Sp3 contributed to the basal expression of the ATF3 gene, whereas EGR-1 played an important role in ECG-induced ATF3 expression in HCT-116 cells, as assessed by EMSA and co-transfection experiments. These results suggested that EGR-1, a tumour suppressor protein, could substantiate ECG's role of ATF3 expression in human colorectal cancer cells. We also found that pro-oxidant activity of ECG contributed to ECG-induced ATF3 expression.

Protein kinase R, IkappaB kinase-beta and NF-kappaB are required for human rhinovirus induced pro-inflammatory cytokine production in bronchial epithelial cells

Rhinovirus infections cause the majority of acute exacerbations of airway diseases such as asthma and chronic obstructive pulmonary disease, with increased pro-inflammatory cytokine production by infected bronchial epithelial cells contributing to disease pathogenesis. Theses diseases are a huge cause of morbidity worldwide, and contribute a major economic burden to healthcare costs. Current steroid based treatments are only partially efficient at controlling virus induced inflammation, which remains an unmet therapeutic goal. Although NF-kappaB has been implicated, the precise mechanisms of rhinovirus induction of pro-inflammatory gene expression in bronchial epithelial cells are unclear. We hypothesised that rhinovirus replication and generation of dsRNA was an important process of pro-inflammatory cytokine induction. Using pharmalogical (2-aminopurine and a new small molecule inhibitor) and genetic inhibition of the dsRNA binding kinase protein kinase R, striking inhibition of dsRNA (polyrIC) and rhinovirus induced CCL5, CXCL8 and IL-6 protein was observed. Using confocal microscopy, rhinovirus induced protein kinase R phosphorylation co-located with NF-kappaB p65 nuclear translocation. Focusing on CXCL8, both rhinovirus infection and dsRNA treatment required IkappaB kinase-beta for induction of CXCL8. Analysis of cis-acting sites in the CXCL8 promoter revealed that both rhinovirus infection and dsRNA treatment upregulated CXCL8 promoter activation via NF-kappaB and NF-IL6 binding sites. Together, the results demonstrate the importance of dsRNA in induction of pro-inflammatory cytokines by rhinoviruses, and suggest that protein kinase R is involved in NF-kappaB mediated gene transcription of pro-inflammatory cytokines via IkappaB kinase-beta. These molecules regulating rhinovirus induction of inflammation represent therapeutic targets.

A module of negative feedback regulators defines growth factor signaling

Signaling pathways invoke interplays between forward signaling and feedback to drive robust cellular response. In this study, we address the dynamics of growth factor signaling through profiling of protein phosphorylation and gene expression, demonstrating the presence of a kinetically defined cluster of delayed early genes that function to attenuate the early events of growth factor signaling. Using epidermal growth factor receptor signaling as the major model system and concentrating on regulation of transcription and mRNA stability, we demonstrate that a number of genes within the delayed early gene cluster function as feedback regulators of immediate early genes. Consistent with their role in negative regulation of cell signaling, genes within this cluster are downregulated in diverse tumor types, in correlation with clinical outcome. More generally, our study proposes a mechanistic description of the cellular response to growth factors by defining architectural motifs that underlie the function of signaling networks.

Interleukin-1-induced NF-κB recruitment to the oxytocin receptor gene inhibits RNA polymerase II–promoter interactions in cultured human myometrial cells

The myometrial oxytocin receptor (OTR) is highly regulated during pregnancy, reaching maximal concentrations near term. These levels are then abruptly reduced in advanced labour and the post-partum period. Our goal was to examine the molecular basis for this reduction, using chromatin immunoprecipitation (ChIP). Interleukin-1alpha (IL1A) treatment of cultured human myometrial cells has previously been shown to reduce steady-state levels of OTR mRNA. We show further that IL1A reduced RNA polymerase II cross-linking to the otr promoter, as reflective of transcriptional inhibition. IL1A also increased the recruitment of nuclear factor kappaB (NF-kappaB) to a site 955 bp upstream from the transcriptional start site. Inhibition of NF-kappaB activation negated the effects of IL1A on polymerase II dissociation, indicating a causal relationship, at least in part, between recruitment of NF-kappaB and detachment of polymerase from the otherwise constitutively active otr promoter. IL1A treatment also resulted in increased histone H4 acetylation in the otr promoter region. Whereas NF-kappaB recruitment and histone acetylation are generally associated with activation of gene expression, our findings show that both processes can be involved in dissociation of RNA polymerase II from an active promoter. The results of these studies suggest that the elevation of IL1 in the myometrium occurring at the end of pregnancy initiates the process of down-regulation of OTRs in advanced labour, resulting in the desensitization of the myometrium to elevated levels of OT in the blood during lactation.

Metformin inhibits proinflammatory responses and nuclear factor-kappaB in human vascular wall cells

OBJECTIVE

Metformin may benefit the macrovascular complications of diabetes independently of its conventional hypoglycemic effects. Accumulating evidence suggests that inflammatory processes participate in type 2 diabetes and its atherothrombotic manifestations. Therefore, this study examined the potential action of metformin as an inhibitor of pro-inflammatory responses in human vascular smooth muscle cells (SMCs), macrophages (Mphis), and endothelial cells (ECs).

METHODS AND RESULTS

Metformin dose-dependently inhibited IL-1beta-induced release of the pro-inflammatory cytokines IL-6 and IL-8 in ECs, SMCs, and Mphis. Investigation of potential signaling pathways demonstrated that metformin diminished IL-1beta-induced activation and nuclear translocation of nuclear factor-kappa B (NF-kappaB) in SMCs. Furthermore, metformin suppressed IL-1beta-induced activation of the pro-inflammatory phosphokinases Akt, p38, and Erk, but did not affect PI3 kinase (PI3K) activity. To address the significance of the anti-inflammatory effects of a therapeutically relevant plasma concentration of metformin (20 micromol/L), we conducted experiments in ECs treated with high glucose. Pretreatment with metformin also decreased phosphorylation of Akt and protein kinase C (PKC) in ECs under these conditions.

CONCLUSIONS

These data suggest that metformin can exert a direct vascular anti-inflammatory effect by inhibiting NF-kappaB through blockade of the PI3K-Akt pathway. The novel anti-inflammatory actions of metformin may explain in part the apparent clinical reduction by metformin of cardiovascular events not fully attributable to its hypoglycemic action.

Regulation of c-Jun N-terminal Kinase and p38 Kinase Pathways in Endothelial Cells

The rapid and transient induction of E-selectin gene expression by inflammatory tumor necrosis factor (TNF)-alpha in endothelial cells is mediated by signaling pathways which involve c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) kinase pathways. To explore this regulation, we first observed that in the continuous presence of cytokine TNF, activation of JNK-1 in both nuclear and cytoplasmic compartments peaked at 15-30 min, with activity returning to uninduced levels by 60 min. Phosphorylation of both the p38 kinase and its molecular target, the nuclear transcription factor, activating transcription factor-2, were transient after TNF-alpha or interleukin (IL)-1beta induction. However, cycloheximide treatment prolonged the TNF-alpha-induced JNK-1 kinase activity beyond 60 min, suggesting that protein synthesis is required to limit this signaling cascade. We investigated the possible role of the dual-specificity phosphatases MAPK phosphatase (MKP)-1 and MKP-2 in limiting cytokine-induced MAPK signaling. Maximum induction of MKP-1 mRNA and nuclear protein levels by TNF-alpha or IL-1beta were noted at 60 min and their expression correlated with the termination of JNK kinase activity, whereas nuclear levels of MKP-2 were not significantly affected by treatment with TNF-alpha or IL-1beta. Transient overexpression of MKP-1 demonstrated significant specific inhibition of E-selectin promoter activity consistent with a regulatory role for dual-specificity phosphatases. Inhibition of MKP-1 expression through the use of small interfering RNAs prolonged the cytokine-induced p38 and JNK kinase phosphorylation. Our results suggest that endogenous inhibitors of the MAPK cascade, such as the dual-specificity phosphatases like MKP-1 may be important for the postinduction repression of MAPK activity and E-selectin transcription in endothelial cells. Thus, these inhibitors may play an important role in limiting the inflammatory effects of TNF-alpha and IL-1beta.

Differential roles of hydrogen peroxide and superoxide in mediating IL-1-induced NF-kappa B activation and iNOS expression in bovine articular chondrocytes

Our previous studies showed that reactive oxygen species (ROS) are required for the pro-inflammatory cytokine interleukin-1 beta (IL-1) to induce the activity of the Nuclear transcription Factor-kappa B (NF-kappa B) and the expression of the inducible isoform of the nitric oxide synthase (iNOS) in bovine articular chondrocytes. This study aimed at elucidating the role of hydrogen peroxide (H(2)O(2)) and the superoxide radical, two major ROS, in mediating those IL-1-induced responses. The results obtained show that chondrocytes produce both H(2)O(2) and superoxide radical in response to IL-1. Treatment of the chondrocyte cultures with H(2)O(2) alone did not induce NF-kappa B activation or iNOS expression. Addition of H(2)O(2) simultaneously with IL-1 did neither enhance nor inhibit NF-kappa B activation and iNOS expression, relatively to treatment with IL-1 alone. Accordingly, treatment with catalase did not inhibit those IL-1-induced responses. Treatment with superoxide dismutase, however, effectively prevented IL-1-induced I kappa B-alpha degradation and iNOS expression. Taken together, the results obtained indicate that superoxide mediates IL-1-induced I kappa B-alpha degradation and the consequent NF-kappa B activation and iNOS expression in chondrocytes, whereas H(2)O(2) does not seem to participate in those IL-1-induced responses. In conclusion, the present study identifies the superoxide radical as the ROS involved in mediating the IL-1-induced signaling pathway that leads to NF-kappa B activation and to the expression of NF-kappa B-dependent genes in bovine articular chondrocytes.

An ATF2-derived peptide sensitizes melanomas to apoptosis and inhibits their growth and metastasis

Melanomas are among the aggressive tumor types because of their notorious resistance to treatment and their high capacity to metastasize. ATF2 is among transcription factors implicated in the progression of melanoma and its resistance to treatment. Here we demonstrate that the expression of a peptide spanning amino acids 50-100 of ATF2 (ATF2(50-100)) reduces ATF2 transcriptional activities while increasing the expression and activity of c-Jun. Altering the balance of Jun/ATF2 transcriptional activities sensitized melanoma cells to apoptosis, an effect that could be attenuated by inhibiting c-Jun. Inhibition of ATF2 via RNA interference likewise increased c-Jun expression and primed melanoma cells to undergo apoptosis. Growth and metastasis of SW1 and B16F10 mouse melanomas were inhibited by ATF2(50-100) to varying degrees up to a complete regression, depending on the mode (inducible, constitutive, or adenoviral delivery) of its expression.

Diacerhein and rhein prevent interleukin-1beta-induced nuclear factor-kappaB activation by inhibiting the degradation of inhibitor kappaB-alpha

Diacerhein and rhein are anthraquinone compounds that ameliorate the course of osteoarthritis. Recent reports also suggest that these compounds may have antiinflammatory properties, but the cellular mechanisms by which they exert antiosteoarthritic and possibly antiinflammatory effects are still incompletely understood. The purpose of this study was to investigate the ability of diacerhein and rhein to inhibit the activation of the transcription factor nuclear factor kappaB, induced by the proinflammatory cytokine interleukin-1beta, in primary monolayer cultures of bovine articular chondrocytes. We also studied the ability of diacerhein and rhein to prevent the expression of the inducible nitric oxide synthase gene, which is driven by nuclear factor-kappaB. We observed that interleukin-1beta induced the degradation of the inhibitor kappaB-alpha protein and the translocation of the protein p65 (a member of the nuclear factor-kappaB family) to the nucleus, which were inhibited by diacerhein and rhein, in a dose-dependent manner. Interleukin-1beta-induced nuclear factor-kappaB binding to a specific (gamma-(32)P)-labelled oligonucleotide probe was also inhibited by treatment of chondrocytes with diacerhein or rhein, as revealed by electrophoretic mobility shift assay. Inducible nitric oxide synthase mRNA and protein synthesis and nitric oxide production were also inhibited by diacerhein and rhein, in a dose-dependent manner. The half-maximal inhibitory concentrations of diacerhein and rhein, relative to nitric oxide production, were 8.2 microM ;and 7.7 microM, respectively. These results suggest that diacerhein and rhein inhibit nuclear factor-kappaB activation and, consequently, the expression of nuclear factor-kappaB-dependent genes, such as the inducible nitric oxide synthase gene, which can explain their antiosteoarthritic and antiinflammatory effects.

Possible participation of intracellular platelet-activating factor in NF-kappaB activation in rat peritoneal macrophages

As we had found previously that thapsigargin, an endomembrane Ca2+-ATPase inhibitor, induces production of intracellular platelet-activating factor (PAF) [Br. J. Pharmacol. 116 (1995) 2141], we decided to investigate the possible roles of intracellular PAF in nuclear factor (NF)-kappaB activation of thapsigargin-stimulated rat peritoneal macrophages. When rat peritoneal macrophages were stimulated with thapsigargin, the level of inhibitory protein of NF-kappaB-alpha (IkappaB-alpha) was decreased and the nuclear translocation of NF-kappaB was increased. The thapsigargin-induced activation of NF-kappaB was inhibited by the PAF synthesis inhibitor SK&F 98625 and the PAF antagonist E6123. Structurally unrelated PAF antagonists such as E5880 and L-652,731 also inhibited the thapsigargin-induced activation of NF-kappaB. Lipopolysaccharide (LPS)-induced activation of NF-kappaB was also suppressed by these drugs. In a culture of rat peritoneal macrophages, exogenously added PAF did not induce degradation of IkappaB-alpha. These findings suggest that the intracellular PAF produced by the stimulation with thapsigargin or LPS is involved in activation of the NF-kappaB pathway.

NF-kappaB activates Bcl-2 expression in t(14;18) lymphoma cells

The t(14;18) translocation, which is characteristic of follicular lymphoma, results in the overexpression of the bcl-2 gene dependent upon regulatory elements within the bcl-2 5' flanking region and the immunoglobulin heavy chain gene enhancers. Conflicting evidence exists on the effects of NF-kappaB expression on Bcl-2 levels in different cell types. Lymphoma cells with the t(14;18) translocation show high levels of nuclear NF-kappaB proteins. We observed decreased levels of endogenous Bcl-2 when the IkappaBalpha-super-repressor was expressed in a t(14;18) cell line. Deletion analysis of the bcl-2 promoter indicated that the repressive effect of the IkappaBalpha-super-repressor occurred through a region that contained no NF-kappaB consensus sequences. This highly active region contained a c-AMP response element (CRE) and several Sp1 binding sites. Chromatin immunoprecipitation assays with antibodies specific for the NF-kappaB and CREB/ATF family members, as well as Sp1, resulted in the isolation of this IkappaBalpha-super-repressor responsive region of the bcl-2 promoter. Mutation of the CRE and the two Sp1 sites in different combinations in bcl-2 reporter constructs resulted in the loss of bcl-2 promoter repression by the IkappaBalpha-super-repressor. We therefore conclude that the activation of bcl-2 by NF-kappaB in t(14;18) lymphoma cells is mediated through the CRE and Sp1 binding sites.

The human immunodeficiency virus-1 Tat protein activates human umbilical vein endothelial cell E-selectin expression via an NF-kappa B-dependent mechanism

Human immunodeficiency virus infection is associated with inflammation and endothelial cell activation that cannot be ascribed to direct infection by the virus or to the presence of opportunistic infections. Factors related to the virus itself, to the host and/or to environmental exposures probably account for these observations. The HIV protein Tat, a viral regulator required for efficient transcription of the viral genome in host cells is secreted from infected cells and taken up by uninfected by-stander cells. Tat can also act as a general transcriptional activator of key inflammatory molecules. We have examined whether Tat contributes to this endothelial cell activation by activating NF-kappaB. Human endothelial cells exposed to Tat in the culture medium activated E-selectin expression with delayed kinetics compared with tumor necrosis factor (TNF). Tat-mediated E-selectin up-regulation required the basic domain of Tat and was inhibited by a Tat antibody. Transfection of human E-selectin promoter-luciferase reporter constructs into Tat-bearing cells or into endothelial cells co-transfected with a Tat expression vector resulted in induction of luciferase expression. Either Tat or TNF activated p65 translocation and binding to an oligonucleotide containing the E-selectin kappaB site 3 sequence. Tat-mediated p65 translocation was also delayed compared with TNF. Neither agent induced new synthesis of p65. A super-repressor adenovirus (AdIkappaBalphaSR) that constitutively sequesters IkappaB in the cytoplasm as well as cycloheximide or actinomycin D inhibited Tat- or TNF-mediated kappaB translocation and E-selectin up-regulation.

17beta-Estradiol inhibits cytokine induction of the human E-selectin promoter

Estradiol has been shown to decrease levels of the cell adhesion molecule E-selectin in cultured cells and in women on hormone replacement therapy. We set out to determine if the mechanism of estradiol action on E-selectin is at the level of its promoter. It was found that estradiol repressed the cytokine-stimulated induction of luciferase activity driven by the human E-selectin promoter in a reporter plasmid (hE-sel-LUC) in co-transfected human hepatoma cells (Hep G2) and human umbilical cord endothelial cells (ECV-304). Repression by estradiol was dependent on the presence of transfected estrogen receptor (ER) alpha or beta expression vectors. The ER antagonist ICI-182,780 blocked the repression by estradiol, confirming the receptor-dependence of the effect. The intact DNA-binding domain of ERalpha was required for estradiol repression of the cytokine-induced stimulation of the promoter in each cell line as demonstrated by the inability of an ER construct with two point mutations in the DNA-binding domain to inhibit reporter activity. Mutation of the NFK-B site at -94 to -85 within the E-selectin promoter led to less stimulation of hE-sel-LUC by interleukin one beta (IL-1beta). Estradiol did not inhibit this IL-1beta stimulated luciferase activity, indicating that the NFK-B site is necessary for ER-mediated inhibition of this promoter. Mutation of the AP-1 site at -500 to -494 within the E-selectin promoter had no effect on the ability of IL-1beta to stimulate its transcription, and estradiol repressed this activation in an ER-dependent manner with identical efficacy and potency in comparison with the wild-type promoter. Therefore, the E-selectin promoter is down-regulated by estradiol working through either ERalpha or ERbeta and requires the NFK-B site at -94 to -85 within the promoter.

Inhibition of cyclic-3',5'-nucleotide phosphodiesterase abrogates the synergism of hypoxia with lipopolysaccharide in the induction of macrophage TNF-alpha production

BACKGROUND

Local tumor necrosis factor (TNF)-alpha production by resident macrophages (M phi) contributes to posttraumatic tissue injury. Hypoxia decreases cellular cyclic adenosine monophosphate (cAMP) levels and enhances M phi secretion of TNF-alpha following lipopolysaccharide (LPS) stimulation. Thus, tissue hypoxia associated with trauma likely synergizes with proinflammatory mediators in the induction of M phi TNF-alpha production through an influence on cAMP generation or degradation. It is unclear whether elevation of cellular cAMP inhibits LPS-stimulated TNF-alpha production by hypoxic M phi. Moreover, it is unknown whether the synergism of hypoxia with LPS can be abrogated by promotion of cAMP generation or inhibition of cAMP degradation.

METHODS

Rat peritoneal M phi were stimulated with Escherichia coli LPS (20 ng/ml) in a normoxic (room air with 5% CO(2)) or hypoxic (95% N(2) with 5% CO(2)) condition. TNF-alpha levels in cell-free supernatants were measured by enzyme-linked immunoassay. The beta-adrenoceptor agonist isoproterenol (ISP; 5.0 microM) and the adenylate cyclase activator forskolin (FSK; 50 microM) were applied to promote cAMP generation. The nonselective cyclic-3',5'-nucleotide phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1.0 mM) and the PDE III-specific inhibitor milrinone (200 microM) were used to inhibit cAMP degradation. The nondegradable cAMP analogue dibutyryl cAMP (dbcAMP; 100 microM) was applied to further determine the role of PDE. RESULTS. Although hypoxia alone had a minimal effect on TNF-alpha production, it dramatically enhanced LPS-stimulated TNF-alpha production (4.08 +/- 0.28 ng/10(6) cells in hypoxia plus LPS vs 1.63 +/- 0.26 ng/10(6) cells in LPS, 2.5-fold, P < 0.01). Promotion of cAMP generation by either ISP or FSK reduced TNF-alpha production by hypoxic cells. However, neither of these two agents abolished the synergism of hypoxia with LPS (1.68 +/- 0.13 ng/10(6) cells in ISP plus hypoxia plus LPS vs 0.55 +/- 0.04 ng/10(6) cells in ISP plus LPS, threefold; 1.17 +/- 0.03 ng/10(6) cells in FSK plus hypoxia plus LPS vs 0.33 +/- 0.02 ng/10(6) cells in FSK plus LPS, 3.5-fold; both P < 0.01). Inhibition of cAMP degradation with IBMX reduced TNF-alpha production in hypoxic cells and abrogated the synergism (0.31 +/- 0.11 ng/10(6) cells in IBMX plus hypoxia plus LPS vs 0.27 +/- 0.04 ng/10(6) cells in IBMX plus LPS, P > 0.05), and the PDE III inhibitor milrinone had a comparable effect. Moreover, dbcAMP also attenuated TNF-alpha production with abrogation of the synergistic effect of hypoxia (0.56 +/- 0.08 ng/10(6) cells in dbcAMP plus hypoxia plus LPS vs 0.46 +/- 0.04 ng/10(6) cells in dbcAMP plus LPS, P > 0.05).

CONCLUSIONS

The results show that elevation of cellular cAMP, either by promotion of generation or by inhibition of degradation, suppresses LPS-stimulated TNF-alpha production in hypoxic M phi. It appears that hypoxia synergizes with LPS in the induction of M phi TNF-alpha production through PDE-mediated cAMP degradation. Inhibition of PDE may be a therapeutic approach for suppression of synergistic induction of M phi TNF-alpha production by hypoxia and LPS in posttraumatic tissue.

Retinoblastoma protein interacts with ATF2 and JNK/p38 in stimulating the transforming growth factor-beta2 promoter

Two highly related transcription factors, ATF2 and ATFa, enhance the activity of the Transforming Growth Factor beta2 (TGF-beta2) promoter via a partial cAMP response element in transfected CHO cells. The retinoblastoma protein (Rb) also activates this promoter and enhances the stimulatory effects of ATF2 but causes near extinction of the effects of ATFa. The site on Rb required for its effects alone and in combination with the ATFs has been mapped mainly to the A/B pockets but the C pocket is also implicated. Whereas MKK7 or JNK expression enhances the actions of both ATFs, MKK6 or p38 expression only augments the effects of ATF2. Immunoprecipitation with Rb antibodies of lysates from transfected cells brings down expressed ATF2 but not ATFa. Expressed JNK and p38 are also found in the anti-Rb immunoprecipitates. ATF2 antibodies bring down expressed Rb, JNK and p38 and expression of Rb enhances the immunoprecipitation of both JNK and p38 by ATF2 antibodies. The results suggest that Rb is acting as a matchmaker by bridging either JNK or p38 with their common substrate ATF2 and, hence, facilitating its activation. Consistent with this suggestion, expression of Rb enhances the phosphorylation of ATF2 in CHO cells.

NFkappa B interacts with serum amyloid A3 enhancer factor to synergistically activate mouse serum amyloid A3 gene transcription

We had previously identified a distal regulatory element (DRE) in the mouse serum amyloid A3 (SAA3) promoter that functions as a cytokine-inducible transcription enhancer. Within this DRE, three functional elements interact with CCAAT/enhancer-binding protein (C/EBP) and SAA3 enhancer factor (SEF) transcription factors. In this study, we show that cotransfection of the SEF expression plasmid with an SAA3/luciferase reporter resulted in 3-5-fold activation of the SAA3 promoter. When SEF-transfected cells were further stimulated with conditioned medium or interleukin-1, SAA3 promoter activity was dramatically increased, suggesting that SEF may cooperate functionally with other interleukin-1-inducible transcription factors to synergistically up-regulate SAA3 gene transcription. Indeed, cotransfection of SEF and NFkappaBp65 expression DNAs resulted in synergistic activation of the SAA3 promoter. Intriguingly, no consensus NFkappaB-binding site was found in the SAA3 promoter region; rather a putative NFkappaB-binding sequence with 3-base pair mismatches was identified in the DRE. When this sequence was used in an electrophoretic mobility shift assay, it interacted with NFkappaBp50, albeit with binding affinities that were several hundredfold lower than that with the consensus NFkappaB probe. Functional cooperation between SEF and NFkappaB was further strengthened by the finding that SEF and NFkappaB formed stable cytokine-inducible protein-protein complexes. Finally, despite its weak binding, mutation of this NFkappaB-binding site nevertheless dramatically reduced both NFkappaBp65- and cytokine-mediated induction of SAA3 promoter. Therefore, the molecular basis for the functional synergy between SEF and NFkappaB may, in part, be the ability of SEF to recruit NFkappaB through physical interactions that lead to enhancement or stabilization of NFkappaB binding to the SAA3 promoter element.

A constitutive active MEK --> ERK pathway negatively regulates NF-kappa B-dependent gene expression by modulating TATA-binding protein phosphorylation

Endotoxin-induced cytokine gene expression is regulated, in part, by NF-kappaB. We have shown that both the ERK and p38 mitogen-activated protein (MAP) kinases are necessary for cytokine gene transcription and that the p38 MAP kinase is required for NF-kappaB-driven transcription, so we hypothesized that the MEK --> ERK pathway regulated NF-kappaB-driven transcription as well. We found that a constitutive active MEK --> ERK pathway inhibited NF-kappaB-driven transcription. In addition, both PD 98059 and a dominant negative ERK2 augmented NF-kappaB-driven transcription; however, neither PD 98059 nor MEK1 altered NF-kappaB activation at any level. The constitutive active MEK --> ERK pathway inhibited the phosphorylation of TBP, which is necessary for both interaction with RelA and binding to the TATA box. Due to the fact that we have shown that the p38 MAP kinase modulates TBP activation, we evaluated the effect of the constitutive active MEK --> ERK pathway on p38 MAP kinase activity. We found that the MEK --> ERK pathway negatively regulates NF-kappaB-driven transcription, in part, by inhibiting p38 MAP kinase activity. Thus, the ERK and p38 MAP kinases have differential effects on NF-kappaB-driven transcription.

Repression of TNF-alpha-induced E-selectin expression by PPAR activators: involvement of transcriptional repressor LRF-1/ATF3

Peroxisome proliferator-activated receptor (PPAR) activators were shown to inhibit the expression of E-selectin of human vascular endothelial cells in response to tumor necrosis factor-alpha (TNF-alpha). Troglitazone, pioglitazone, alpha-clofibrate, and 15-deoxy-Delta12,14-prostaglandin J2 all inhibited the TNF-alpha-stimulated E-selectin gene transcription in reporter assay. To further clarify the underlying transcriptional regulation, nuclear factor(s) that binds to the nuclear factor-endothelial leukocyte adhesion molecule 1 (NF-ELAM1) site of the E-selectin gene promoter was investigated. The activators caused a significant induction of liver regenerating factor 1 (LRF1)/activating transcription factor 3 (ATF3), which bound to the NF-ELAM1 site and repressed the TNF-alpha-induced E-selectin gene expression. From these data, the effect of PPAR activators was mediated, in part, through the induction of LRF1/ATF3. This might provide a novel molecular mechanism of anti-inflammatory effect of PPAR activators.

beta(2)-Integrin blockade driven by E-selectin promoter prevents neutrophil sequestration and lung injury in mice

Interaction of CD11/CD18 beta(2) integrins on polymorphonuclear leukocytes (PMNs) with their counterreceptor, intercellular adhesion molecule-1, on the surface of vascular endothelial cells is a critical event mediating stable PMN adhesion and migration across the pulmonary vascular endothelial barrier. Neutrophil inhibitory factor (NIF), a 41-kDa glycoprotein isolated from the canine hookworm (Ancylostoma caninum), binds to the I domain of CD11a and CD11b and inhibits beta(2) integrin-dependent PMN adhesion. We describe a novel strategy using the endothelial cell-specific E-selectin promoter to induce NIF expression in an inflammation-specific manner in pulmonary vascular endothelial cells. A construct containing NIF cDNA driven by the inducible endothelial cell-specific E-selectin promoter (pESNIF) was transfected into human pulmonary artery endothelial cells (HPAECs). Lipopolysaccharide challenge (known to activate E-selectin) resulted in NIF mRNA and protein expression in transfected HPAECs. NIF expression induced by the E-selectin promoter prevented PMN adhesion to the activated HPAECs, whereas PMNs adhered avidly to activated HPAECs in the absence of NIF expression. To address the utility of this approach in conditionally preventing in vivo PMN sequestration, we injected mice intravenously with cationic liposomes containing the pESNIF construct. Analysis of lung tissue showed that intraperitoneal challenge of Escherichia coli resulted in NIF expression. Inflammation-specific NIF expression induced by the E-selectin promoter prevented lung PMN sequestration and vascular injury induced by E coli challenge. These studies suggest the feasibility of conditionally blocking beta(2) integrin function at sites where the endothelium is activated and thereby of locally preventing PMN activation and migration responses that lead to tissue inflammation.

Inhibitory effect of ATF3 antisense oligonucleotide on ectopic growth of HT29 human colon cancer cells

ATF3 is a transcription factor belonging to the Jun / Fos family whose mouse homologue (TI-241) was isolated, using the differential screening method, from B16 mouse melanoma cells as a blood-borne metastasis-associated gene. Here we show the tumorigenicity-inhibiting effect of an antisense oligonucleotide designed to reduce the expression of ATF3 in HT29 colon cancer cells. HT29 cells were reported to metastasize to the skin after intravenous inoculation. The antisense oligonucleotide inhibited cell attachment to the collagen-coated floor of the plates and invasion of HT29 cells in vitro, which are thought to be two important factors in the process of cancer metastasis and ectopic tumor growth. While the antisense oligonucleotide had no effect on cell growth of HT29 cells in vitro, mice that were inoculated subcutaneously with HT29 cells and treated with the antisense oligonucleotide survived longer than the control mice due to the inhibition of tumor growth in vivo. These show that ATF3 plays an important role in the ectopic growth / metastasis of HT29 colon cancer cells.

Adaptive responses of the endothelium to stress

It is now established that endothelial cells acquire several functional properties in response to a diverse array of extracellular stimuli. This expression of an altered phenotype is referred to as endothelial cell activation, and it includes several activities that promote inflammation and coagulation. While it is recognized that endothelial cell activation has a principal role in host defense, recent studies also demonstrate that endothelial cells are capable of complex molecular responses that protect the endothelium against various forms of stress including heat shock, hypoxia, oxidative stress, shock, ischemia-reperfusion injury, toxins, wounds, and mechanical stress. In this review, we examine endothelial cell genotypic and phenotypic responses to stress. Also, we highlight important cellular stress responses that, although not yet demonstrated directly in endothelial cells, likely exist as part of the repertoire of stress responses in endothelium. A detailed understanding of the molecular mechanisms mediating the adaptive responses of endothelial cells to stress should facilitate the development of novel therapeutics to aid in the management of diverse surgical diseases and their complications.

Induction of E-selectin expression by double-stranded RNA and TNF-alpha is attenuated in murine aortic endothelial cells derived from double-stranded RNA-activated kinase (PKR)-null mice

The adherence of leukocytes on the endothelium is mediated in part by the transient expression of the E-selectin adhesion molecule. Because we have previously shown that the dsRNA-activated kinase PKR mediates dsRNA induction of NF-kappaB, we used murine aortic endothelial (MuAE) cells isolated from wild-type and PKR-null mice to investigate the role of PKR in the induction of E-selectin expression by dsRNA (pIC) and TNF-alpha. E-selectin mRNA and protein expression was inducible by both pIC and TNF-alpha in wild-type MuAE cells, whereas induction of E-selectin expression by these agents was defective in PKR-null MuAE cells. Induction of E-selectin promoter activity and NF-kappaB DNA binding activity were substantially reduced in pIC- or TNF-alpha-treated PKR-null cells, indicating a role for PKR in both pIC and TNF-alpha induction of E-selectin via an NF-kappaB-dependent pathway. In PKR-null cells, pIC-mediated degradation of IkappaBbeta is deficient. Activation of this pathway requires the PKR-dependent degradation of the IkappaBbeta protein. Moreover, both phosphorylated and unphosphorylated activating transcription factor 2 DNA-binding activities were reduced in PKR-null aortic endothelial cells. These results indicate that the PKR is required for full activation of E-selectin expression by pIC and TNF-alpha in primary mouse aortic endothelial cells identifying activating transcription factor 2 as a new target for PKR-dependent regulation and suggest a role for PKR in leukocyte adhesion.

The p38 mitogen-activated protein kinase is required for NF-kappaB-dependent gene expression. The role of TATA-binding protein (TBP)

Endotoxin-induced cytokine gene transcription in monocytes and macrophages is regulated in part by NF-kappaB. We have previously shown that the p38 mitogen-activated protein (MAP) kinase is necessary for endotoxin-induced cytokine gene transcription. Due to the fact that most cytokine promoter sequences have active NF-kappaB sites, we hypothesized that the p38 MAP kinase was necessary for NF-kappaB-dependent gene expression. We found that NF-kappaB-dependent gene expression was reduced to near control levels with either SB 203580 or a dominant-negative p38 MAP kinase expression vector. Inhibition of the p38 MAP kinase did not alter NF-kappaB activation at any level, but it significantly reduced the DNA binding of TATA-binding protein (TBP) to the TATA box. The dominant-negative p38 MAP kinase expression vector interfered with the direct interaction of native TFIID (TBP) with a co-transfected p65 fusion protein. Likewise, this dominant-negative plasmid also interfered with the direct interaction of a co-transfected TBP fusion protein with the native p65 subunit. The p38 kinase also phosphorylated TFIID (TBP) in vitro, and SB 203580 inhibited phosphorylation of TFIID (TBP) in vivo. Thus, the p38 MAP kinase regulates NF-kappaB-dependent gene transcription, in part, by modulating activation of TFIID (TBP).

Integration of Rac-dependent regulation of cyclin D1 transcription through a nuclear factor-kappaB-dependent pathway

The small GTP-binding protein Rac1, a member of the Ras superfamily, plays a fundamental role in cytoskeleton reorganization, cellular transformation, the induction of DNA synthesis, and superoxide production. Cyclin D1 abundance is rate-limiting in normal G(1) phase progression, and the abundance of cyclin D1 is induced by activating mutations of both Ras and Rac1. Nuclear factor-kappaB (NF-kappaB) proteins consist of cytoplasmic hetero- or homodimeric Rel-related proteins complexed to a member of the IkappaB family of inhibitor proteins. In the current studies, activating mutants of Rac1 (Rac(Leu-61), Rac(Val-12)) induced cyclin D1 expression and the cyclin D1 promoter in NIH 3T3 cells. Induction of cyclin D1 by Rac1 required both an NF-kappaB and an ATF-2 binding site. Inhibiting NF-kappaB by overexpression of an NF-kappaB trans-dominant inhibitor (nonphosphorylatable IkappaBalpha) reduced cyclin D1 promoter activation by the Rac1 mutants, placing NF-kappaB in a pathway of Rac1 activation of cyclin D1. Specific amino acid mutations in the amino-terminal effector domain of Rac(Leu-61) had comparable effects on NF-kappaB transcriptional activity and activation of the cyclin D1 promoter. The NF-kappaB factors Rel A (p65) and NF-kappaB(1) (p50) induced the cyclin D1 promoter, requiring both the NF-kappaB binding site and the ATF-2 site. Stable overexpression of Rac(Leu-61) increased binding of Rel A and NF-kappaB(1) to the cyclin D1 promoter NF-kappaB site. Activation of Rac1 in NIH 3T3 cells induces both NF-kappaB binding and activity and enhances expression of cyclin D1 through an NF-kappaB and ATF-2 site in the proximal promoter, suggesting a critical role for NF-kappaB in cell cycle regulation through cyclin D1 and Rac1.