Nuclear NF-κB Activity Research Articles

Increased Nuclear Thioredoxin-1 Potentiates Cadmium-Induced Cytotoxicity

Cadmium (Cd) is a widely dispersed environmental agent that causes oxidative toxicity through mechanisms that are sensitive to thioredoxin-1 (Trx1). Trx1 is a cytoplasmic protein that translocates to nuclei during oxidative stress. Recent research shows that interaction of Trx1 with actin plays a critical role in cell survival and that increased nuclear Trx-1 potentiates proinflammatory signaling and death in cell and mouse models. These observations indicate that oxidative toxicity caused by low-dose Cd could involve disruption of actin-Trx1 interaction, nuclear Trx1 translocation, and potentiation of proinflammatory cell death mechanisms. In this study, we investigated the role of nuclei-localized Trx1 in Cd-induced inflammation and cytotoxicity using in vitro and in vivo models. The results show that Cd stimulated nuclear translocation of Trx1 and p65 of NF-κB. Elevation of Trx1 in nuclei in in vitro cells and kidney of transgenic mice potentiated Cd-stimulated NF-κB activation and cell death. Cd-stimulated Trx1 nuclear translocation and NF-κB activation were inhibited by cytochalasin D, an inhibitor of actin polymerization, suggesting that actin regulates Trx1 nuclear translocation and NF-κB activation by Cd. A nuclear-targeted dominant negative form of Trx1 blocked Cd-stimulated NF-κB activation and decreased cell death. Addition of zinc, known to antagonize Cd toxicity by increasing metallothionein, had no effect on Cd-stimulated nuclear translocation of Trx1 and NF-κB activation. Taken together, the results show that nuclear translocation and accumulation of redox-active Trx1 in nuclei play an important role in Cd-induced inflammation and cell death.

Curcumin inhibits iron overload-induced hepatocytic apoptosis and nuclear factor-κB activity

Iron is an essential micronutrient for human beings but its overload induces various diseases of liver, the main body storage site for iron, such as liver fibrosis. Curcumin is a natural polyphenol derived from turmeric and has been used widely. Its pharmacological action has attracted great attention in recent years. The apoptosis of rat cultured hepatocytes was induced by FeNTA (ferric nitrilotriacetate)-induced Iron overload. The present study was to examine the effect of curcumin at low concentrations on FeNTA-induced apoptosis of hepatocytes and elucidate the underlying mechanisms. After the incubation of hepatocytes with 100 µmol/L FeNTA in the presence or absence of 1 - 10 µmmol/L of curcumin, a series of analyses were performed, including the analyses of hepatocytic apoptosis, the expressions of proteins relating with the regulations of cell apoptosis, caspase-3 activity, the production of reactive oxygen species (ROS) and nuclear factor NF-κB activity. Curcumin reduced the FeNTA-induced hepatocytic apoptosis by 46.65% and significantly down-regulated the protein levels of Bcl-2 and Bcl-XL. In contrast, it had no effect on the protein levels of Bax and Bad. The curcumin treatment reduced FeNTA-caused production of ROS and caspase-3 activity by 45.01% and 59.71% respectively. And the NF-κB activity was also inhibited. Curcumin at low concentrations reduces iron overload-caused hepatocytic apoptosis and NF-κB activity, the key regulatory transcription factor for the inflammation-related gene expression in cultured hepatocyte.

PI3Kγ activation is required for LPS-induced reactive oxygen species generation in respiratory epithelial cells

In this study, we investigated the molecular basis of reactive oxygen species (ROS) generation induced by lipopolysaccharide (LPS) in A549 cells--an alveolar epithelial cell line. A549 cells or normal human bronchial epithelial (NHBE) cells were stimulated with LPS. ROS generation was measured in A549 cells or NHBE cells pre-treated with a selective inhibitor of phosphatidylinositol 3-kinase γ (PI3Kγ), AS 605240, PI3Kγ siRNA, or a ROS scavenger, pyridoxamine (PM). Treatment of A549 cells or NHBE cells with LPS caused a significant increase in intracellular ROS generation. Pretreatment with the PI3Kγ inhibitor, AS 605240 decreased the LPS-induced increase of ROS generation, phosphorylation of Akt, and production of phosphatidyl 3,4,5-trisphosphate in A549 cells. In addition, interference with siRNA for PI3Kγ significantly reduced LPS-induced ROS generation in A549 cells. Treatment of A549 cells with LPS or hydrogen peroxide increased the nuclear factor-κB (NF-κB) in the nucleus, accompanying an increase in phosphorylation of inhibitory κB-α, degradation of the protein, and reduction of cytosolic NF-κB. Pretreatment with AS 605240 reduced these LPS-induced changes. In addition, pretreatment with PM or N-acetyl cysteine resulted in inhibition of nuclear NF-κB activation. These results suggest that PI3Kγ plays a key role in LPS-induced ROS generation in alveolar epithelial cells, thereby activating NF-κB.

The molecular mechanism of luteolin-induced apoptosis is potentially related to inhibition of angiogenesis in human pancreatic carcinoma cells

Luteolin has been shown to have a strong anticancer effect on various cancer models via programmed cell death (apoptosis). However, the fundamental mechanisms of these effects are still unclear. In the present study, we examined the question of whether or not luteolin can inhibit proliferation of pancreatic carcinoma cells, via apoptosis. We used three human pancreatic carcinoma cell lines, PANC-1, CoLo‑357 and BxPC-3 in our study. In luteolin-treated pancreatic carcinoma cells, typical features of apoptosis were observed. Luteolin increased the expression of the pro-apoptotic protein Bax and decreased the expression of the anti-apoptotic protein Bcl-2, with a concomitant increase in the levels of caspase-3 and cleaved PARP after treatment for 24h. Luteolin inhibited HUVEC proliferation and vessel growth in CAM invivo. In addition, the concentration of VEGF in the conditioned medium from human pancreatic carcinoma cells was downregulated by luteolin. Pancreatic carcinoma cells, pretreated with luteolin, could decrease the capillary-like structure formation by HUVEC, which was analyzed by a co-culture system. The abatement of VEGF secretion was related to the inhibition of VEGF mRNA expression, which may be regulated by inhibiting the transcription activity of nuclear transcription factor NF-κB.

Role of Nuclear Factor-κB in Oxidative Stress Associated with Rabies Virus Infection of Adult Rat Dorsal Root Ganglion Neurons

Recent studies in an experimental model of rabies showed major structural changes in the brain involving neuronal processes that are associated with severe clinical disease. Cultured adult rat dorsal root ganglion (DRG) neurons infected with the challenge virus standard-11 strain of rabies virus (CVS) showed axonal swellings and immunostaining for 4-hydroxy-2-nonenal (4-HNE), indicating evidence of lipid peroxidation associated with oxidative stress and reduced axonal growth compared to that of mock-infected DRG neurons. We have evaluated whether nuclear factor (NF)-κB might act as a critical bridge linking CVS infection and oxidative stress. On Western immunoblotting, CVS infection induced expression of the NF-κB p50 subunit compared to that of mock infection. Ciliary neurotrophic factor, a potent activator of NF-κB, had no effect on mock-infected rat DRG neurons and reduced the number of 4-HNE-labeled puncta. SN50, a peptide inhibitor of NF-κB, and CVS infection had an additive effect in producing axonal swellings, indicating that NF-κB is neuroprotective. The fluorescent signal for subunit p50 was quantitatively evaluated in the nucleus and cytoplasm of mock- and CVS-infected rat DRG neurons. At 24 h postinfection (p.i.), there was a significant increase in the nucleus/cytoplasm ratio, indicating increased transcriptional activity of NF-κB, perhaps as a response to stress. At both 48 and 72 h p.i., there was significantly reduced nuclear localization of NF-κB. CVS infection may induce oxidative stress by inhibiting nuclear activation of NF-κB. A rabies virus protein may directly inhibit NF-κB activity. Further investigations are needed to gain a better understanding of the basic mechanisms involved in the oxidative damage associated with rabies virus infection.

NF-κB contributes to the detrimental effects of social isolation after experimental stroke

Social isolation (SI) is increasingly recognized as a risk factor for stroke. Individuals with lack of social support systems have an increased incidence of stroke, poorer recovery, and greater functional decline after injury compared to individuals with social support. Attesting to the importance of social factors in stroke outcome is that these same effects can be reproducibly demonstrated in animals; social interaction improves behavioral deficits and reduces damage after experimental stroke, whereas SI enhances injury. The mechanism by which SI exacerbates injury is unclear. We investigated the role of nuclear factor-kappaB (NF-κB) signaling in male mice that were pair housed (PH) with an ovariectomized female prior to random assignment into continued PH or SI for 7 days prior to middle cerebral artery occlusion. The effects of SI on infarct volume and functional recovery were assessed at 72 h post-stroke. Nuclear NF-κB levels and activity were assessed by Western blot and transcriptional assays. SI significantly exacerbated infarct size in both male and female mice compared to PH mice. SI mice had delayed functional recovery compared to PH mice. An elevation of systemic IL-6 levels, increased nuclear NF-κB transcriptional activity, and enhanced nuclear translocation of NF-κB was seen in SI stroke animals. Interference with NF-κB signaling using either a pharmacological inhibitor or genetically engineered NF-κB p50 knockout mice abolished the detrimental effects of SI on both infarct size and functional recovery. This suggests that NF-κB mediates the detrimental effects of SI.

The Role of Nuclear Factor- B in Oxidative Stress Associated with Rabies Virus Infection (P03.263)

Objective: To investigate the role of NF-κB in rabies virus-induced oxidative stress in neurons. Background Recent studies in an experimental mouse model of rabies have shown that there are major structural changes in the brain involving neuronal processes that are associated with severe clinical disease. Cultured adult dorsal root ganglion (DRG) neurons are a good in vitro model for studying mechanisms involved in rabies virus – induced degeneration of neurites, because, unlike other neuronal cell types, these neurons are permissive to rabies virus infection. DRG neurons infected with the CVS strain of rabies virus show axonal swellings and immunostaining for 4-hydroxy-2-nonenal (4-HNE), indicating evidence of lipid peroxidation associated with oxidative stress, and also reduced axonal growth vs. mock-infected DRG neurons. Design/Methods: The expression and localization of NF-κB were evaluated by Western immunoblotting and immunofluorescence, respectively, in mock- versus CVS-infected rat DRG neurons. The effects of ciliary neurotrophic factor (CNTF), a potent activator of NF-κB, and SN50, a peptide inhibitor of NF-κB, were also evaluated. Results: CNTF had no effect on mock-infected rat DRG neurons, and was neuroprotective for CVS-neurons in reducing the number of 4-HNE-labeled puncta. SN50 and CVS infection had an additive effect in producing axonal swellings, suggesting that NF-κB is neuroprotective. CVS infection induced the expression of protein for the p50 subunit of NF-κB. The fluorescent signal for p50 was quantitatively evaluated in the nucleus and cytoplasm of mock- and CVS-infected rat DRG neurons. At 24 hrs p.i. there was a significant increase in the nucleus:cytoplasm ratio, indicating increased transcriptional activity of NF-kB, perhaps as a response to stress, whereas at both 48 and 72 hrs p.i. there was significantly reduced nuclear localization of NF-kB. Conclusions: CVS infection may induce oxidative stress by preventing nuclear activation of NF-κB. A rabies virus protein may directly inhibit NF-kB activity. Supported by: Canadian Institutes of Health Research. Disclosure: Dr. Jackson has nothing to disclose. Dr. Kammouni has nothing to disclose. Dr. Hasan has nothing to disclose. Dr. Fernyhough has nothing to disclose.

Abstract 3197: Functional microscale cell-based systems for studying hematologic cancers in complex microenvironments

Abstract Our ability to improve treatments for blood-related cancers such as multiple myeloma (MM) is currently hindered by limitations in lab procedures for studying cell signaling mechanisms in drug resistance. Conventional assays for studying signal transduction (gel shift assays) require large quantities of cell sample (> 100,000 cells per condition) that often cannot be acquired safely and reliably from primary bone marrow aspirations of different patients. Furthermore, in vitro assays often do not adequately represent key aspects of the complex bone marrow microenvironment, including spatial organization of stromal cell types. The objective of this study was to develop a new functional assay using microfluidics technology to examine signal transduction events, specifically in improved in vitro microenvironments, for non-adherent cells such as those associated with hematologic cancers, and for low cell number applications (∼1000 cells per condition) including patient samples. Successful development of this assay would provide an alternative to gel shift assays and streamline experiments. We developed microscale cell culture chambers that used a surface tension-based passive pumping method for fluidic delivery, obviating the need for external pumps and tubing commonly used in microfluidic systems, thus reducing dead volume and cell loss. To validate the platform, non-adherent RPMI8226 cells (human MM cell line) were cultured, treated with cytokines/drugs, fixed, and immunostained to determine cytoplasmic versus nuclear localization of NF-κB subunit RelA as a measure of canonical NF-κB activation. Fluorescent images of RelA were analyzed using custom image analysis for calculating ratio of nuclear to cytoplasmic signals (intensity ratio, IR) at single cell resolution. IR values of cells in a population were calculated to determine overall nuclear translocation and NF-κB activation. Results showed fluorescence immunostaining coupled with custom image analysis was able to detect dose-dependent TNF-α activation of NF-κB, and dose-dependent inhibition of NF-κB activity by bortezomib treatment. Ongoing work involves applying the platform to study effects of various drug treatments on NF-κB signaling in primary patient MM cells in monoculture and in coculture with bone marrow stromal cells. Our results demonstrate the platform is a functional, enabling tool for studying single-cell NF-κB signal transduction with low numbers of non-adherent cells. The platform is extensible to other hematologic cancers, applicable for other transcription factors (e.g., STAT3), amenable to coculture studies, and has potential to enable novel experiments with limited primary samples that may have significant impact in translational research. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3197. doi:1538-7445.AM2012-3197

Prior exercise training alleviates the lung inflammation induced by subsequent exposure to environmental cigarette smoke

Environmental cigarette smoke (CS) contains many compounds that are harmful to the respiratory system and lead to chronic lung inflammation and other lung diseases. Exercise training is known to confer protection against diseases with chronic inflammation by reducing inflammatory response in human or experimental animals. In this study, we investigated the preventive effect of exercise training against lung inflammation induced by environmental CS. In this study, two groups of mice received air exposure with (the exercise group) or without (the control group) exercise training for 8 weeks and another two groups received air exposure for the first 4 weeks and CS exposure for the following 4 weeks with (the exercise+CS group) or without (the CS group) exercise training for 8 weeks. As compared with lung tissues of control and exercise groups, those of the CS group showed significantly increased bronchoalveolar-capillary permeability, inflammatory cell infiltration, epithelial thickening, expression of proliferating cell nuclear antigen, mucin 2, cytokines, chemokines, adhesion molecules and activation of NF-κB. These CS-induced pathophysiologic consequences were largely prevented in the exercise + CS group. Collectively, prior exercise training may protect against lung inflammation induced by environmental CS in mice by attenuating the activation of NF-κB and the production of inflammatory mediators.

Relationship of the expression of IL-32 on NF-κB and p-p38 MAP kinase pathways in human esophageal cancer.

59 Background: Esophageal cancer is the seventh leading cause of cancer death in males in the United States, and a strong link has been demonstrated between inflammation and esophageal cancer. Interleukin (IL)-32 is a recently described proinflammatory cytokine characterized by the induction of nuclear factor NF-κB activation, the p38 MAPK also plays an important role in key cellular processes related to inflammation and cancer. We investigated whether the IL-32 expression may be involved in esophageal carcinogenesis through modulates the activity of NF-κB and p- p38 MAPK. Methods: Malignant esophageal and blood samples were obtained from 65 operable untreated patients, normal samples was obtained from 35 patients operated for other reasons as control. IL-32 expression, phosphorylated P38MAPK are visualized by immunohistochemistry, RT-PCR for IL-32 mRNA expression and for detected cytokines (TNF-α, IL-1 β, IL-6 and IL-8 ), NF-kB phosphorylation was analyzed by immunoblotting, ELISA for further detection IL-32 and cytokines concentration in the patients sera. Results: IL-32 expression was increased in malignant esophageal samples compared with control (P = 0.01),and mostly in adenocarcinomas type (76.7%) and (21%) in squamous cell carcinomas. IL-32 expression detected at the mRNA level (P = 0.007 vs. control), and its correlated with NF-κB activation (P = 0.003), and up-regulation of phospho p38MAPK (P= 0.004), and also increased in the cytokines concentration compared with the control samples. Conclusions: Understanding the pathway of IL-32 expression to stimulates the secretion cytokines via the activation of NF-κB and up-regulation of p- p38MAPK might be responsible in the esophageal carcinogenesis and used as tumor marker.

Free fatty acids induce transglutaminase 2‐dependent apoptosis in hepatocytes via ER stress‐stimulated PERK pathways

Non-alcoholic steatohepatitis (NASH), a progressive form of fatty liver, shares histological similarities with alcoholic steatohepatitis (ASH), including accumulated fat, hepatic apoptosis, and fibrous tissues in the liver, but the molecular mechanisms responsible for hepatic apoptosis remain unclear. We previously reported that transglutaminase 2 (TG2), induced in the nuclei of ethanol-treated hepatocytes, crosslinks and inactivates the transcription factor Sp1, leading to hepatic apoptosis. In this study, we investigated whether a similar change is involved in NASH, and if so, how TG2 and crosslinked Sp1 (CLSp1) are induced. Elevated nuclear TG2 and CLSp1 formation was demonstrated in NASH patients, as well as increased activation of apoptosis inducing factor (AIF) and release of cytochrome c. In Hc human normal hepatocytes treated with free fatty acids (FFAs), biochemical analyses revealed that ethanol and FFAs provoked fat accumulation, endoplasmic reticulum (ER) stress, increased nuclear factor kappa B (NFκB), and nuclear TG2. Salubrinal, a selective inhibitor of the ER stress-induced pancreatic ER kinase (PERK) signaling pathway, inhibited NFκB activation, nuclear TG2 expression, and apoptosis only if it was induced by FFAs, but not by ethanol. These results suggest that FFAs could increase ER stress and lead to nuclear NFκB activation and TG2 induction through PERK-dependent pathways, resulting in TG2-mediated apoptosis accompanying crosslinking and inactivation of Sp1, activation of AIF, and release of cytochrome c.

The postprandial inflammatory response after ingestion of heated oils in obese persons is reduced by the presence of phenol compounds

Heating during the process of cooking alters the chemical properties of foods and may affect subsequent postprandial inflammation. We tested the effects of four meals rich in different oils subjected to heating on the postprandial inflammatory metabolism of peripheral blood mononuclear cells (PBMCs). Twenty obese participants received four breakfasts following a randomized crossover design, consisting of milk and muffins made with different oils (virgin olive oil (VOO), sunflower oil (SFO), and a mixture of seeds oil (SFO/canola oil) with added either dimethylpolysiloxane (SOD), or natural antioxidants from olive mill wastewater alperujo (phenols; SOP)), previously subjected to 20 heating cycles. Postprandial inflammatory status in PBMCs was assessed by the activation of nuclear NF-κB, the concentration in cytoplasm of the NF-κB inhibitor (IκB-α), the mRNA levels of NF-κB subunits and activators (p65, IKKβ, and IKKα) and other inflammatory molecules (TNF-α, IL-1β, IL-6, MIF, and JNK), and lipopolysaccharide (LPS) levels. VOO and SOP breakfasts reduced NF-κB activation, increased IκB-α, and decreased LPS plasma concentration. SFO increased IKKα, IKKβ, p65, IL-1b, IL-6, MIF, and JNK mRNA levels, and plasma LPS. Oils rich in phenols, whether natural (VOO) or artificially added (SOP), reduce postprandial inflammation, compared with seed oil (sunflower).

In vitro anti-neuroblastoma activity of saquinavir and its association with imatinib

Neuroblastoma (NB) has a poor prognosis when in advanced stages, highlighting the need for new therapeutic options. The human immunodeficiency virus (HIV) protease inhibitor saquinavir is active invitro against chronic myeloid leukaemia cells, in synergy with the tyrosine kinase inhibitor imatinib. Here, we evaluated the effects of saquinavir, alone or in association with imatinib, on cell proliferation (count of viable cells after trypan blue exclusion), apoptosis (AnnexinV binding) and invasion (through a transwell membrane coated with Matrigel) in SJ-N-KP, IMR5, AF-8, SK-N-SH and SK-N-BE NB lines, all expressing c-kit and PDGF-R (determined by flow cytometry). Saquinavir showed a dose-dependent anti-proliferative and anti-invasive activity on NB lines, increased by the association with imatinib when the two drugs were utilized at clinically attainable concentrations. The same low saquinavir concentrations inhibited in NB cells the nuclear activation of NF-κB (Western immuno-blotting for nuclear NF-κB p50 and p65). Saquinavir at high concentrations also exerted a pro-apoptotic activity on NB lines, significantly increased by the association with imatinib. In conclusion, saquinavir and imatinib are both drugs utilized for long-term therapies, with good oral bioavailability and a well-known toxicity profile. The anti-NB activity of saquinavir and of its association with imatinib suggests a potential usefulness in the treatment of NB, particularly for remission maintenance.

Abstract 17470: NF-κB Activation Down Stream of Tuber Sclerosis Complex -mTOR Signaling pathway is Suppressed in Doxorubicin-Induced Cardiotoxicity

The signaling networks that coordinate cell survival and cell death are poorly defined in the heart. The mammalian target of rapamycin (mTOR) is a highly conserved serine threonine kinase centrally involved in vital processes including growth, proliferation, and gene transcription. However, mTOR's role in regulating cell survival under normal or disease conditions has not been undetermined. Previously we established a cytoprotective role for the cellular factor NF-κB in ventricular myocytes. Notably, we demonstrated that NF-κB activation was necessary and sufficient for basal cell survival and suppressing mitochondrial perturbations during hypoxic injury. Herein, we provide new compelling evidence that activation of IKK-NF-κB signaling pathway down-stream of mTOR suppresses mitochondrial perturbations and cell death during metabolic stress imposed by nutrient deprivation or hypoxia. In contrast to wild type cells, constitutive activation of mTOR in tuber sclerosis complex (TSC) 2 -/- cells displayed marked increased mTOR targets p-P70S6, p-4EBP-1 and S6 protein. Interestingly, a significant increase in nuclear NF-κB activity and NF-κB gene transcription was also observed in TSC 2 -/- cells. Interestingly, in in vivo and in vitro models of Doxorubicin (Dox) -induced cardiotoxicity we observed a marked reduction in mTOR and NF-κB activity. However, basal NF-κB activity and cell viability were significantly reduced upon mTOR inactivation following metabolic stress or hypoxia. Moreover, basal Bnip3 gene transcription and cell death were significantly increased in cells treated with DOX and defective for mTOR activity. IKKβ- mediated activation of NF-κB restored mTOR activity and suppressed cell death induced by Bnip3 in DOX treated cells. To our knowledge our data provide the first direct evidence that operationally links mTOR and cell survival via IKKβ-NF-κB mediated repression of Bnip3.

Hyperandrogenism sensitizes mononuclear cells to promote glucose-induced inflammation in lean reproductive-age women

Hyperandrogenism and chronic low-grade inflammation are related in polycystic ovary syndrome (PCOS), but it is unknown whether hyperandrogenemia can activate inflammation. We determined the effect of oral androgen administration on fasting and glucose-stimulated nuclear factor-κB (NF-κB) activation and expression and related markers of inflammation in mononuclear cells (MNC) of lean reproductive-age women. Sixteen lean, ovulatory reproductive-age women were treated with 130 mg of DHEA or placebo (n = 8 each) for 5 days in a randomized, controlled, double-blind fashion. Nuclear activation of NF-κB, p65 and p105 NF-κB subunit RNA, TNFα and IL-1β mRNA, and NF-κB p65 and inhibitory-κB (IκB) protein were quantified from MNC obtained while fasting and 2 h after glucose ingestion, before and after DHEA or placebo administration. Before treatment, subjects receiving DHEA or placebo exhibited no differences in androgens or any inflammatory markers while fasting and after glucose ingestion. Compared with placebo, DHEA administration raised levels of testosterone, androstenedione, and DHEA-S, increased the percent change in fasting and glucose-challenged activated NF-κB, p65, p105, TNFα, and IL-1β RNA and p65 protein, and decreased the percent change in fasting and glucose-challenged IκB protein. We conclude that elevation of circulating androgens to the range observed in PCOS upregulates the NF-κB inflammation pathway in lean reproductive-age women. Thus, hyperandrogenemia activates and sensitizes MNC to glucose in this population.

Heme oxygenase-1 downregulate the activity of nuclear factor NF-κB and protect the damage of cardiocyte induced by lipopolysaccharide in rats

ObjectiveTo determine whether HO-1 played a important role in the protection of cardiocyte in the lipopolysaccharide-induced acute cardiocyte injury model.MethodCardiocyte was isolated from SD neonate rat, and was enrolled into...

C-Jun N-terminal kinase phosphorylates DCP1a to control formation of P bodies

Cytokines and stress-inducing stimuli signal through c-Jun N-terminal kinase (JNK) using a diverse and only partially defined set of downstream effectors. In this paper, the decapping complex subunit DCP1a was identified as a novel JNK target. JNK phosphorylated DCP1a at residue S315 in vivo and in vitro and coimmunoprecipitated and colocalized with DCP1a in processing bodies (P bodies). Sustained JNK activation by several different inducers led to DCP1a dispersion from P bodies, whereas IL-1 treatment transiently increased P body number. Inhibition of TAK1-JNK signaling also affected the number and size of P bodies and the localization of DCP1a, Xrn1, and Edc4. Transcriptome analysis further identified a central role for DCP1a in IL-1-induced messenger ribonucleic acid (mRNA) expression. Phosphomimetic mutation of S315 stabilized IL-8 but not IκBα mRNA, whereas overexpressed DCP1a blocked IL-8 transcription and suppressed p65 NF-κB nuclear activity. Collectively, these data reveal DCP1a as a multifunctional regulator of mRNA expression and suggest a novel mechanism controlling the subcellular localization of DCP1a in response to stress or inflammatory stimuli.

4-Hydroxy-2-hexenal-induced apoptosis in human renal proximal tubular epithelial cells

The aldehyde products of lipid peroxidation such as 4-hydroxy-2-hexenal (HHE) might be responsible for the pathogenesis of kidney injury. The present study was aimed to investigate the effects of HHE on renal tubular epithelial cells and its signaling mechanisms. Human proximal tubular epithelial (HK-2) cells were treated with 10 μM of HHE. Cell viability was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The fluorescent probe 2',7'-dichlorofluorescein diacetate was used to measure intracellular levels of reactive oxygen species (ROS). The protein expression of NF-κB, mitogen-activated protein kinase (MAPK), pro-apoptoic Bax and anti-apoptotic protein Bcl-2 was determined by semiquantitative immunoblotting. Apoptosis was assessed by flow cytometry analysis after the cells were stained by fluorescein isothiocyanate-conjugated annexin V protein and propidium iodine. Treatment with various doses of HHE resulted in dose-dependent decreases of cell viability and increases of ROS. HHE increased the expression of p38 MAPK, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). HHE induced NF-κB activation and IκB-α degradation. Increased nuclear NF-κB activation was blocked by inhibitors of ERK (PD98059) or JNK (SP600125), but not affected by p38 MAPK inhibitor (SB203580). Flow cytometry analysis revealed HHE-induced apoptosis. HHE decreased the expression of Bcl-2, while it increased that of Bax, which was attenuated by the treatment of NF-κB inhibitor (Bay 11-7082) or N-acetyl-L-cysteine (NAC). An inhibition of NF-κB prevented HHE-induced apoptosis. HHE-induced tubular cell apoptosis is mediated by modulation of Bax and Bcl-2 via ROS generation. HHE-mediated accumulation of ROS may induce redox-sensitive transcription factor, NF-κB, through activation of ERK and JNK, resulting in cellular apoptosis in HK-2 cells.

Hydroquinone Stimulates Inflammatory Functions in Microvascular Endothelial Cells via NF-κB Nuclear Activation

Hydroquinone impairs several leucocyte cell functions, which alter the immune response. Although endothelial cell functions are important for the development of immune responses, hydroquinone actions on endothelial cell have not been shown. Therefore, the effect of hydroquinone exposure (10 or 100 μM for 2 hr) on primary culture of microvascular endothelial cells (PMECs) obtained from the cremaster muscle of Wistar rats incubated in the presence or absence of lipopolysaccharide (LPS, 2 μg/mL) was investigated. Hydroquinone treatment induced the membrane expression of cell adhesion molecules (CAMs) from the immunoglobulin superfamilies ICAM-1 (intercellular), VCAM-1(vascular) and PECAM-1 (platelet endothelial) and induced the secretion of cytokines interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α). The effects were dependent on transcriptional modifications because enhanced CAM mRNA expression as well as both cytokines and nuclear factor κB (NF-κB) nuclear activation was found. These effects may be due to the direct action of hydroquinone rather than its quinone metabolites, because endothelial cells do not present myeloperoxidase enzyme and hydroquinone incubation did not induce the expression of cytochrome P450 2E1 (CYP2E1) or prostaglandin H synthase 1. In addition, the incubation of endothelial cells with benzoquinone (10 μM, 2 hr) impaired PECAM-1 expression and did not modify NF-κB nuclear activation. Taken together, the data herein presented reveal that hydroquinone evokes pro-inflammatory properties in endothelial cells that are triggered by the enhancement of NF-κB nuclear translocation-dependent gene transcription.

Andrographolide Inhibits ICAM-1 Expression and NF-κB Activation in TNF-α-Treated EA.hy926 Cells

Several lines of evidence indicate that inflammation and endothelial cell dysfunction are important initiating events in atherosclerosis. Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine, induces the expression of cell adhesion molecules and results in monocyte adherence and atheromatous plaque formation. Andrographolide (AP) is a major bioactive diterpene lactone in Andrographis paniculata that has anti-inflammatory activity. A previous study demonstrated the role of heme oxygenase 1 (HO-1) in the inhibition of TNF-α-induced ICAM-1 expression by AP. The present study investigated the effect of AP on the IKK/NF-κB signaling pathway, which mediates TNF-α-induced ICAM-1 expression in EA.hy926 cells. Similar to the previous study, AP inhibited TNF-α-induced ICAM-1 mRNA and protein levels, its expression on the cell surface, and subsequent adhesion of HL-60 cells to EA.hy926 cells. AP inhibited TNF-α-induced κB inhibitor (IκB) kinase (IKK) and IκBα activation, p65 nuclear translocation, NF-κB and DNA binding activity, and promoter activity of ICAM-1. Although AP increased the intracellular cAMP concentration and induced the phosphorylation of cAMP response element-binding protein (CREB), knocking down CREB protein expression by transfecting the cells with CREB-specific small interfering RNA did not relieve the inhibition of ICAM-1 expression by AP. Taken together, these results suggest that AP down-regulates TNF-α-induced ICAM-1 expression at least in part via attenuation of activation of NF-κB in EA.hy926 cells rather than through activation of CREB. The results suggest that AP may have potential as a cardiovascular-protective agent.