Redox modulation of chromatin remodeling: impact on histone acetylation and deacetylation, NF-kappaB and pro-inflammatory gene expression

Suppression of lipopolysaccharide- and tumour necrosis factor-alpha-induced interleukin (IL)-8 expression by glucocorticoids involves changes in IL-8 promoter acetylation

There is accumulating evidence that the transrepressional effect of glucocorticoids in down-regulating proinflammatory gene expression might be regulated by an action on histone acetylation. To investigate this, we studied the effect of two glucocorticoids (dexamethasone and triamcinolone acetonide) on reducing lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-alpha-induced interleukin (IL)-8 release in a monocytic cell line and two lymphocytic cell lines (HUT-78 and Jurkat). The effect of the histone deacetylase inhibitor trichostatin A (TSA) on LPS- and TNF-alpha-induced IL-8 release and its repression by glucocorticoids was also examined. LPS and TNF-alpha induced IL-8 release in all three cell lines and this induction was inhibited by both dexamethasone and triamcinolone. Pretreatment of cells with TSA enhanced basal and LPS- and TNFalpha-stimulated IL-8 release in all three cell lines. TSA also attenuated the inhibitory effect of glucocorticoids on stimulated IL-8 release. Chromatin immunoprecipitation assays confirmed that LPS and TNF-alpha enhanced histone acetylation at the IL-8 promoter and that this was inhibited by triamcinolone in all three cell types. Changes in histone acetylation at the IL-8 are important in its regulation by proinflammatory and anti-inflammatory agents, and modulation of this activity may have therapeutic potential in inflammatory conditions.

Transcriptome analysis of gills from the white shrimp Litopenaeus vannamei infected with White Spot Syndrome Virus

We report the analysis of 872 cDNA clones from a WSSV-infected white shrimp Litopenaeus vannamei gill cDNA library. Comparison against the GenBank protein and nucleotide sequences identified 87% (E < or = 10(-2)) as previously known genes, while 13% are novel sequences. The 601 ESTs (87%) represent transcripts of 276 genes. These genes were categorized into 12 groups according to their functions. The more abundant categories were (1) ribosomal proteins (21%), (2) WSSV transcripts and sequences without homology to proteins deposited in the non-redundant database (15%), (3) hypothetical proteins (12%) which include genes never described in shrimp and (4) metabolism related proteins (9%). We also found genes involved in stress and immune response; and only one involved in ion transport. Full-length sequences of keratinocyte associated protein 2 (KCP2), selenoprotein M (SelM), chicadae, prohibitin and oncoprotein nm23 are reported. Their mRNAs steady state levels in addition to ferritin, changed at different times post-WSSV infection as estimated by RT-PCR. These results suggest that WSSV alters gene expression in gills and has led to the identification of novel white shrimp specific genes.

Histone deacetylase as therapeutic target in a rodent model of hemorrhagic shock: effect of different resuscitation strategies on lung and liver

BACKGROUND

DNA transcription is regulated in part by acetylation of nuclear histones, controlled by 2 groups of enzymes: histone deacetylases (HDAC) and histone acetyl transferases (HAT). We have shown previously that hemorrhage and resuscitation are associated with HDAC/HAT imbalance, which influences the acetylation status of cardiac histones. The goals of this study were to determine whether: (1) resuscitation after hemorrhage affects histone acetylation in a fluid- and organ-specific fashion; and (2) administration of HDAC inhibitors influences histone acetylation and subsequent gene expression.

METHODS

In the first experiment, rats (n = 6/group) were subjected to volume-controlled hemorrhage and resuscitated with: (1) racemic lactated Ringer's (DL-LR); (2) L-lactated Ringer's (L-LR); (3) 7.5% hypertonic saline (HTS); (4) ketone Ringer's (KR); or (5) pyruvate Ringer's (PR). Control groups included: (6) no hemorrhage (Sham); and (7) hemorrhage with no resuscitation (NR). In the second experiment (n = 5/group), 3 HDAC inhibitors, valproic acid (VPA), trichostatin A (TSA), and suberoylanilide hydroxamic acid (SAHA), were added to normal saline and used as fluid for resuscitation. At the end of resuscitation, lung and liver tissues were subjected to subcellular protein fractionation and Western blotting to analyze histone acetylation. In addition, cDNA microarrays and RT-PCR were used to measure expression of selected genes.

RESULTS

Hemorrhage did not change the level of histone acetylation in lungs, whereas resuscitation predominantly hyperacetylated histones. An analysis of histone acetylation on 10 lysine sites showed that L-LR, HTS, and KR resuscitation caused the largest number of changes (7, 6, and 6 respectively). SAHA hyperacetylated 7 sites in liver and affected expression of 57 genes (44 up, 13 down).

CONCLUSIONS

Resuscitation with various fluids, as well as infusion of pharmacologic HDAC inhibitors affects histone acetylation in a fluid- and organ-specific fashion, even when administered post-insult for a limited period of time. Uniquely affected genes are associated with metabolism, cellular growth, proliferation, differentiation, transformation, and cellular signaling.

Phenylbutyrate, a histone deacetylase inhibitor, protects against Adriamycin-induced cardiac injury

Cardiac injury is a major complication for oxidative-stress-generating anticancer agents exemplified by Adriamycin (ADR). Recently, several histone deacetylase inhibitors (HDACIs) including phenylbutyrate (PBA) have shown promise in the treatment of cancer with little known toxicity to normal tissues. PBA has been shown to protect against oxidative stress in normal tissues. Here, we examined whether PBA might protect heart against ADR toxicity in a mouse model. The mice were i.p. injected with ADR (20 mg/kg). PBA (400 mg/kg/day) was i.p. injected 1 day before and daily after the ADR injection for 2 days. We found that PBA significantly decreased the ADR-associated elevation of serum lactate dehydrogenase and creatine kinase activities and diminished ADR-induced ultrastructural damages of cardiac tissue by more than 70%. Importantly, PBA completely rescued ADR-caused reduction of cardiac functions exemplified by ejection fraction and fraction shortening, and increased cardiac manganese superoxide dismutase (MnSOD) protein and activity. Our results reveal a previously unrecognized role of HDACIs in protecting against ADR-induced cardiac injury and suggest that PBA may exert its cardioprotective effect, in part, by the increase of MnSOD. Thus, combining HDACIs with ADR could add a new mechanism to fight cancer while simultaneously decrease ADR-induced cardiotoxicity.

Sepsis since the discovery of Toll-like receptors: disease concepts and therapeutic opportunities

OBJECTIVE

Sepsis and its sequelae are the leading cause of death in critically ill patients. Discovery in the late 1990s of Toll-like receptors as primary sensors of microbial infection led to significant advances in understanding the pathogenesis of sepsis, including emerging differences between Gram-positive and Gram-negative infection and the potential for the manipulation of Toll-like receptors for the treatment of sepsis. This review describes these advances.

METHODS

Bibliographic search of the literature since 1999, with particular emphasis on the conceptual and therapeutic implications of Toll-like receptors for patients with systemic sepsis.

RESULTS AND CONCLUSIONS

Toll-like receptors initiate the inflammatory processes that underlie the clinical response to infection and therefore represent an important putative target for therapeutic intervention.

Inflammatory reactive oxygen species-mediated hemopoietic suppression in Fancc-deficient mice

Patients with the genomic instability syndrome Fanconi anemia (FA) commonly develop progressive bone marrow (BM) failure and have a high risk of cancer. Certain manifestations of the disease suggest that the FA immune system is dysfunctional and may contribute to the pathogenesis of both BM failure and malignancies. In this study, we have investigated inflammation and innate immunity in FA hemopoietic cells using mice deficient in Fanconi complementation group C gene (Fancc). We demonstrate that Fancc-deficient mice exhibit enhanced inflammatory response and are hypersensitive to LPS-induced septic shock as a result of hemopoietic suppression. This exacerbated inflammatory phenotype is intrinsic to the hemopoietic system and can be corrected by the re-expression of a wild-type FANCC gene, suggesting a potential role of the FANCC protein in innate immunity. LPS-mediated hemopoietic suppression requires two major inflammatory agents, TNF-alpha and reactive oxygen species. In addition, LPS-induced excessive accumulation of reactive oxygen species in Fancc(-/-) BM cells overactivates the stress kinase p38 and requires prolonged activation of the JNK. Our data implicate a role of inflammation in pathogenesis of FA and BM failure diseases in general.

Vaticanol B, a resveratrol tetramer, regulates endoplasmic reticulum stress and inflammation

Enhanced endoplasmic reticulum (ER) stress has been implicated in various pathological situations including inflammation. During a search for compounds that regulate ER stress, we identified vaticanol B, a tetramer of resveratrol, as an agent that protects against ER stress-induced cell death. Vaticanol B suppressed the induction of unfolded protein response-targeted genes such as glucose-regulated protein 78 (GRP78) and C/EBP-homologous protein (CHOP) after cells were treated with ER stressors. Analysis in the mouse macrophage cell line RAW 264.7 revealed that vaticanol B also possesses a strong anti-inflammatory activity. Production of a variety of inflammatory modulators such as tumor necrosis factor-alpha, nitric oxide, and prostaglandin E(2) was inhibited by vaticanol B to a much greater extent than by monomeric or dimeric resveratrol after exposure of cells to lipopolysaccharide. Further investigations to determine the common mechanisms underlying the regulation of ER stress and inflammation by vaticanol B disclosed an important role for vaticanol B in regulation of basic gene expression and in prevention of the protein leakage from the ER into the cytosol in both conditions. These results suggest that vaticanol B is a novel anti-inflammatory agent that improves the ER environment by reducing the protein load on the ER and by maintaining the membrane integrity of the ER.

The pro-inflammatory cytokines, IL-1beta and TNF-alpha, inhibit intestinal alkaline phosphatase gene expression

High levels of the pro-inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), are present in the gut mucosa of patients suffering form various diseases, most notably inflammatory bowel diseases (IBD). Since the inflammatory milieu can cause important alterations in epithelial cell function, we examined the cytokine effects on the expression of the enterocyte differentiation marker, intestinal alkaline phosphatase (IAP), a protein that detoxifies bacterial lipopolysaccharides (LPS) and limits fat absorption. Sodium butyrate (NaBu), a short-chain fatty acid and histone deacetylase (HDAC) inhibitor, was used to induce IAP expression in HT-29 cells and the cells were also treated +/- the cytokines. Northern blots confirmed IAP induction by NaBu, however, pretreatment (6 h) with either cytokine showed a dose-dependent inhibition of IAP expression. IAP Western analyses and alkaline phosphatase enzyme assays corroborated the Northern data and confirmed that the cytokines inhibit IAP induction. Transient transfections with a reporter plasmid carrying the human IAP promoter showed significant inhibition of NaBu-induced IAP gene activation by the cytokines (100 and 60% inhibition with IL-1beta and TNF-alpha, respectively). Western analyses showed that NaBu induced H4 and H3 histone acetylation, and pretreatment with IL-1beta or TNF-alpha did not change this global acetylation pattern. In contrast, chromatin immunoprecipitation showed that local histone acetylation of the IAP promoter region was specifically inhibited by either cytokine. We conclude that IL-1beta and TNF-alpha inhibit NaBu-induced IAP gene expression, likely by blocking the histone acetylation within its promoter. Cytokine-mediated IAP gene silencing may have important implications for gut epithelial function in the setting of intestinal inflammatory conditions.

Inhibitory effects of saikosaponin-d on CCl4-induced hepatic fibrogenesis in rats

AIM: To investigate the suppressive effect of saikosaponin-d (SSd) on hepatic fibrosis in rats induced by CCl₄ injections in combination with alcohol and high fat, low protein feeding and its relationship with the expression of nuclear factor-κB (NF-κB), tumor necrosis factor-alpha (TNF-α) and interleukins-6 (IL-6).

METHODS: Hepatic fibrosis models were induced by subcutaneous injection of CCl₄ at a dosage of 3 mL/kg in rats. At the same time, rats in treatment groups were injected intraperitoneally with SSd at different doses (1.0, 1.5 and 2.0 mg/kg) once daily for 6 wk in combination with CCl₄, while the control group received olive oil instead of CCl₄. At the end of the experiment, rats were anesthetized and killed (except for 8 rats which died during the experiment; 2 from the model group, 3 in high-dose group, 1 in medium-dose group and 2 in low-dose group). Hematoxylin and eosin (HE) staining and Van Gieson staining were used to examine the changes in liver pathology. The levels of alanine aminotransferase (ALT), triglyeride (TG), albumin (ALB), globulin (GLB), hyaluronic acid (HA) and laminin (LN) in serum and the content of hydroxyproline (HYP) in liver were measured by biochemical examinations and radioimmuneoassay, respectively. In addition, the expression of TNF-α and IL-6 in liver homogenate was evaluated by enzyme-linked immunosorbent assay (ELISA) and the levels of NF-κBp65 and I-κBα in liver tissue were analyzed by Western blotting.

RESULTS: Both histological examination and Van Gieson staining demonstrated that SSd could attenuate the area and extent of necrosis and reduce the scores of liver fibrosis. Similarly, the levels of ALT, TG, GLB, HA, and LN in serum, and the contents of HYP, TNF-α and IL-6 in liver were all significantly increased in model group in comparison with those in control group. Whereas, the treatment with SSd markedly reduced all the above parameters compared with the model group, especially in the medium group (ALT: 412 ± 94.5 IU/L vs 113.76 ± 14.91 IU/L, TG: 0.95 ± 0.16 mmol/L vs 0.51 ± 0.06 mmol/L, GLB: 35.62 ± 3.28 g/L vs 24.82 ± 2.73 g/L, HA: 42.15 ± 8.25 ng/mL vs 19.83 ± 3.12 ng/mL, LN: 27.56 ± 4.21 ng/mL vs 13.78 ± 2.57 ng/mL, HYP: 27.32 ± 4.32 μg/mg vs 16.20 ± 3.12 μg/mg, TNF-α: 4.38 ± 0.76 ng/L vs 1.94 ± 0.27 ng/L, IL-6: 28.24 ± 6.37 pg/g vs 12.72 ± 5.26 pg/g, respectively, P < 0.01). SSd also decreased ALB in serum (28.49 ± 4.93 g/L vs 37.51 ± 3.17 g/L, P < 0.05). Moreover, the expression of NF-κB p65 in the liver of treated groups was lower than that in model groups while the expression of I-κBα was higher in treated group than in model group (P < 0.01). The expression of NF-κBp65 and TNF-α had a positive correlation with the level of HA in serum of rats after treatment with CCl₄ (r = 0.862, P < 0.01; r = 0.928, P < 0.01, respectively).

CONCLUSION: SSd attenuates CCl₄-induced hepatic fibrosis in rats, which may be related to its effects of hepato-protective and anti-inflammation properties, the down-regulation of liver TNF-α, IL-6 and NF-κBp65 expression and the increased I-κBα activity in liver.

Hypoxia-induced and stress-specific changes in chromatin structure and function

Cellular adaptation to stress relies on specific, regulated responses to evoke changes in gene expression. Stresses such as hypoxia, heat shock, oxidative stress and DNA-damage activate signaling cascades that ultimately lead to either induction or repression of stress-responsive genes. In this review, we concentrate on the mechanisms by which stress-induced signaling promotes alterations in chromatin structure, whether the read-out is activation or repression of transcription. Specific alterations in chromatin are highly regulated and dictated by the type of imposed stress. Our primary focus is on the types of chromatin alterations that occur under hypoxic conditions, which exist within a majority of tumors, and to compare these to changes in chromatin structure that occur in response to a wide variety of cellular stresses.

Histone acetyltransferase p300 modulates gene expression in an epigenetic manner at high blood alcohol levels

When rats are fed ethanol intragastrically at a constant rate for 1 month, the urinary alcohol level (UAL) cycles over 7-9 day intervals. At the peak UAL, the liver is hypoxic shifting the redox state to a reduced rate. Microarray analysis done on livers at the UAL peaks shows changes in approximately 1300 gene expression compared to the pair-fed controls. To determine the mechanism of the gene expression changes, histone acetylation regulation was investigated in liver nuclear extracts at the peaks and troughs of the UAL and their pair-fed controls. No change occurred in SirT-1. P300, a histone acetyltransferase (HAT), which acetylates histone H3 on lysine 9, was increased at the peaks. Histone 3 acetylated at lysine 9 was also increased at the peaks. This indicates that the up regulated genes at the UAL peaks resulted from an increase in p300 transcription regulation, epigenetically. P300 activates transcription of numerous genes in response to signal transcription factors such as H1F 1alpha, increased in the nucleus at UAL peaks. Signal transduction pathways, such as NFkappaB, AP-1, ERK, JNK, and p38 were not increased at the peaks. beta-Catenin was increased in the nuclear extract at the UAL troughs, where increased gene expression was absent. The increase in gene expression at the peaks was due, in part, to increased acetylation of histone 3 at lysine 9.

Histone deacetylation: an important mechanism in inflammatory lung diseases

Inflammatory lung diseases are characterised by increased expression of multiple inflammatory genes that are regulated by proinflammatory transcription factors, such as NF-kappaB. Gene expression is regulated by modifications such as acetylation of core histones through the concerted action of coactivators such as CBP (cAMP-response element binding protein (CREB)-binding protein) which have intrinsic histone acetyltransferase (HAT) activity and are able to recruit other HAT enzymes. Conversely gene repression is mediated via histone deacetylases (HDAC) and other corepressors. In biopsies from asthmatic subjects there is an increase in HAT activity and some reduction in HDAC activity. Both of these changes are partially reversed by corticosteroid therapy. Corticosteroids switch off inflammatory genes in asthma through a combination of a direct inhibition of HAT activity and by the recruitment of HDAC2 to the activated NF-kappaB-stimulated inflammatory gene complex. In chronic obstructive pulmonary disease (COPD), a corticosteroid insensitive disease, there is a reduction in HDAC activity and HDAC2 expression, which may account for the amplified inflammation and resistance to the actions of corticosteroids. The reduction in HDAC2 may be secondary to oxidative and nitrative stress as a result of cigarette smoking and severe inflammation. This may also occur to differing degrees in severe asthma, smoking asthmatic patients and cystic fibrosis. Similar mechanisms may also account for the steroid resistance seen within latent adenovirus infections. The reduction in HDAC activity induced by oxidative stress can be restored by theophylline, acting through specific kinases, which may be able to reverse steroid resistance in COPD and other inflammatory lung diseases. The modulation of HAT/HDAC activity may lead to the development of novel anti-inflammatory approaches to inflammatory lung diseases that are currently difficult to treat.

Polyphenols and cancer cell growth

Polyphenols constitute an important group of phytochemicals that gained increased research attention since it was found that they could affect cancer cell growth. Initial evidence came from epidemiologic studies suggesting that a diet that includes regular consumption of fruits and vegetables (rich in polyphenols) significantly reduces the risk of many cancers. In the present work we briefly review the effects of polyphenols on cancer cell fate, leading towards growth, differentiation and apoptosis. Their action can be attributed not only to their ability to act as antioxidants but also to their ability to interact with basic cellular mechanisms. Such interactions include interference with membrane and intracellular receptors, modulation of signaling cascades, interaction with the basic enzymes involved in tumor promotion and metastasis, interaction with oncogenes and oncoproteins, and, finally, direct or indirect interactions with nucleic acids and nucleoproteins. These actions involve almost the whole spectrum of basic cellular machinery--from the cell membrane to signaling cytoplasmic molecules and to the major nuclear components--and provide insights into their beneficial health effects. In addition, the actions justify the scientific interest in this class of compounds, and provide clues about their possible pharmaceutical exploitation in the field of oncology.

The role of mitochondrial function in the oocyte and embryo

Mitochondria have long been known to be the powerhouses of the cell but they also contribute to redox and Ca2+ homeostasis, provide intermediary metabolites and store proapoptotic factors. Mitochondria have a unique behavior during development. They are maternally transmitted with little (if any) paternal contribution, and they originate from a restricted founder population, which is amplified during oogenesis. Then, having established the full complement of mitochondria in the fully grown oocyte, there is no further increase of the mitochondrial population during early development. The localization of mitochondria in the egg during maturation and their segregation to blastomeres in the cleaving embryo are strictly regulated. Gradients in the distribution of mitochondria present in the egg have the potential to give rise to blastomeres receiving different numbers of mitochondria. Such maternally inherited differences in mitochondrial distribution are thought to play roles in defining the long-term viability of the blastomere in some cases and embryonic axes and patterning in others. Mitochondria may also regulate development by a number of other means, including modulating Ca2+ signaling, and the production of ATP, reactive oxygen species, and intermediary metabolites. If the participation of mitochondria in the regulation of sperm-triggered Ca2+ oscillations is now well established, the role of other properties of mitochondrial function during development remain largely unexplored probably due to the difficulty of accessing the mitochondrial compartment in an embryo. Maintaining a functional complement of maternally derived mitochondria is vital for the early embryo. Mitochondrial dysfunction may not only compromise developmental processes but also trigger apoptosis in the embryo. This dual role for mitochondria (to maintain life or to commit to cell death) may well represent a quality control system in the early embryo that will determine whether the embryo proceeds further into development or is quickly eliminated.

Neuroprotective effects of curcumin

Neurodegenerative diseases result in the loss of functional neurons and synapses. Although future stem cell therapies offer some hope, current treatments for most of these diseases are less than adequate and ourbest hope is to prevent these devastating diseases. Neuroprotective approaches work best prior to the initiation of damage, suggesting that some safe and effective prophylaxis would be highly desirable. Curcumin has an outstanding safety profile and a number of pleiotropic actions with potential for neuroprotective efficacy, including anti-inflammatory, antioxidant, and anti-protein-aggregate activities. These can be achieved at submicromolar levels. Curcumin's dose-response curves are strongly dose dependent and often biphasic so that in vitro data need to be cautiously interpreted; many effects might not be achievable in target tissues in vivo with oral dosing. However, despite concerns about poor oral bioavailability, curcumin has at least 10 known neuroprotective actions and many of these might be realized in vivo. Indeed, accumulating cell culture and animal model data show that dietary curcumin is a strong candidate for use in the prevention or treatment of major disabling age-related neurodegenerative diseases like Alzheimer's, Parkinson's, and stroke. Promising results have already led to ongoing pilot clinical trials.

Endoplasmic reticulum stress induces myostatin precursor protein and NF-kappaB in cultured human muscle fibers: relevance to inclusion body myositis

Sporadic-inclusion body myositis (s-IBM) is the most common progressive muscle disease of older persons. It leads to pronounced muscle fiber atrophy and weakness, and there is no successful treatment. We have previously shown that myostatin precursor protein (MstnPP) and myostatin (Mstn) dimer are increased in biopsied s-IBM muscle fibers, and proposed that MstnPP/Mstn increase may contribute to muscle fiber atrophy and weakness in s-IBM patients. Mstn is known to be a negative regulator of muscle fiber mass. It is synthesized as MstnPP, which undergoes posttranslational processing in the muscle fiber to produce mature, active Mstn. To explore possible mechanisms involved in Mstn abnormalities in s-IBM, in the present study we utilized primary cultures of normal human muscle fibers and experimentally modified the intracellular micro-environment to induce endoplasmic-reticulum (ER)-stress, thereby mimicking an important aspect of the s-IBM muscle fiber milieu. ER stress was induced by treating well-differentiated cultured muscle fibers with either tunicamycin or thapsigargin, both well-established ER stress inducers. Our results indicate for the first time that the ER stress significantly increased MstnPP mRNA and protein. The results also suggest that in our system ER stress activates NF-kappaB, and we suggest that MstnPP increase occurred through the ER-stress-activated NF-kappaB. We therefore propose a novel mechanism leading to the Mstn increase in s-IBM. Accordingly, interfering with pathways inducing ER stress, NF-kappaB activation or its action on the MstnPP gene promoter might prevent Mstn increase and provide a new therapeutic approach for s-IBM and, possibly, for muscle atrophy in other neuromuscular diseases.

Cytotoxic effect of curcumin on malaria parasite Plasmodium falciparum: inhibition of histone acetylation and generation of reactive oxygen species

The emergence of multidrug-resistant parasites is a major concern for malaria control, and development of novel drugs is a high priority. Curcumin, a natural polyphenolic compound, possesses diverse pharmacological properties. Among its antiprotozoan activities, curcumin was potent against both chloroquine-sensitive and -resistant Plasmodium falciparum strains. Consistent with findings in mammalian cell lines, curcumin's prooxidant activity promoted the production in P. falciparum of reactive oxygen species (ROS), whose cytotoxic effect could be antagonized by coincubation with antioxidants and ROS scavengers. Curcumin treatment also resulted in damage of both mitochondrial and nuclear DNA, probably due to the elevation of intracellular ROS. Furthermore, we have demonstrated that curcumin inhibited the histone acetyltransferase (HAT) activity of the recombinant P. falciparum general control nonderepressed 5 (PfGCN5) in vitro and reduced nuclear HAT activity of the parasite in culture. Curcumin-induced hypoacetylation of histone H3 at K9 and K14, but not H4 at K5, K8, K12, and K16, suggested that curcumin caused specific inhibition of the PfGCN5 HAT. Taken together, these results indicated that at least the generation of ROS and down-regulation of PfGCN5 HAT activity accounted for curcumin's cytotoxicity for malaria parasites.

Inhibition of tumor necrosis factor-alpha-inducible inflammatory genes by interferon-gamma is associated with altered nuclear factor-kappaB transactivation and enhanced histone deacetylase activity

Airway smooth muscle (ASM) cells can act as effector cells in the initiation and/or perpetuation of airway inflammation in asthma by producing various inflammatory chemokines or cytokines. Previous studies from our laboratory and others showed that the combination of tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) or endogenous IFNbeta results in a synergistic induction of various pro-inflammatory genes, including CD38 and regulated upon activation normal T-cell expressed and secreted (RANTES), in ASM cells. In contrast to these studies, we found that IFNgamma (1000 U/ml) markedly inhibited TNFalpha-induced expression of interleukin (IL)-6, IL-8, and eotaxin by 66.29+/-3.33, 43.86+/-7.11, and 63.25+/-6.46%, respectively. These genes were also found to be NF-kappaB-dependent in that TNFalpha-induced expression of IL-6, IL-8, and eotaxin was dose-dependently inhibited by the selective IKKbeta inhibitor 4-(2'-aminoethyl)amino-1,8-dimethylimidazo[1,2-a]quinoxaline (BMS-345541) (1-30 microM). Using a luciferase reporter construct containing kappaB sites, we found that IFNgamma (10-1000 U/ml) inhibits NF-kappaB-dependent gene transcription in a dose-dependent manner. Moreover, IFNgamma failed to affect TNFalpha-induced IkappaKbeta phosphorylation or IkappaB degradation as well as nuclear NF-kappaB/DNA interaction. It is noteworthy that IFNgamma decreases TNFalpha-induced histone acetyl transferase (HAT) and increases histone deacetylase (HDAC) activities. Finally, trichostatin A, an HDAC inhibitor, prevents IFNgamma inhibitory action on TNFalpha-induced gene expression. Together, our data indicate that IFNgamma is a potent inhibitor of specific TNFalpha-inducible inflammatory genes by acting on NF-kappaB transactivation via the modulation of HDAC function.

Regulation of inflammation and redox signaling by dietary polyphenols

Reactive oxygen species (ROS) play a key role in enhancing the inflammation through the activation of NF-kappaB and AP-1 transcription factors, and nuclear histone acetylation and deacetylation in various inflammatory diseases. Such undesired effects of oxidative stress have been found to be controlled by the antioxidant and/or anti-inflammatory effects of dietary polyphenols such as curcumin (diferuloylmethane, a principal component of turmeric) and resveratrol (a flavonoid found in red wine). The phenolic compounds in fruits, vegetables, tea and wine are mostly derivatives, and/or isomers of flavones, isoflavones, flavonols, catechins, tocopherols, and phenolic acids. Polyphenols modulate important cellular signaling processes such as cellular growth, differentiation and host of other cellular features. In addition, they modulate NF-kappaB activation, chromatin structure, glutathione biosynthesis, nuclear redox factor (Nrf2) activation, scavenge effect of ROS directly or via glutathione peroxidase activity and as a consequence regulate inflammatory genes in macrophages and lung epithelial cells. However, recent data suggest that dietary polyphenols can work as modifiers of signal transduction pathways to elicit their beneficial effects. The effects of polyphenols however, have been reported to be more pronounced in vitro using high concentrations which are not physiological in vivo. This commentary discusses the recent data on dietary polyphenols in the control of signaling and inflammation particularly during oxidative stress, their metabolism and bioavailability.

Nitric oxide regulates mitochondrial oxidative stress protection via the transcriptional coactivator PGC-1alpha

Nitric oxide (NO) has both prooxidant and antioxidant activities in the endothelium; however, the molecular mechanisms involved are still a matter of controversy. PGC-1alpha [peroxisome proliferators-activated receptor (PPAR) gamma coactivator 1-alpha] induces the expression of several members of the mitochondrial reactive oxygen species (ROS) detoxification system. Here, we show that NO regulates this system through the modulation of PGC-1alpha expression. Short-term (<12 h) treatment of endothelial cells with NO donors down-regulates PGC-1alpha expression, whereas long-term (>24 h) treatment up-regulates it. Treatment with the NOS inhibitor l-NAME has the opposite effect. Down-regulation of PGC-1alpha by NO is mediated by protein kinase G (PKG). It is blocked by the soluble guanylate cyclase (sGC) inhibitor ODQ and the PKG inhibitor KT5823, and mimicked by the cGMP analog 8-Br-cGMP. Changes in PGC-1alpha expression are in all cases paralleled by corresponding variations in the mitochondrial ROS detoxification system. Cells that transiently overexpress PGC-1alpha from the cytomeglovirus (CMV) promoter respond poorly to NO donors. Analysis of tissues from eNOS(-/-) mice showed reduced levels of PGC-1alpha and the mitochondrial ROS detoxification system. These data suggest that NO can regulate the mitochondrial ROS detoxification system both positively and negatively through PGC-1alpha.

Cigarette smoke induces proinflammatory cytokine release by activation of NF-κB and posttranslational modifications of histone deacetylase in macrophages

Cigarette smoke-mediated oxidative stress induces an inflammatory response in the lungs by stimulating the release of proinflammatory cytokines. Chromatin remodeling due to histone acetylation and deacetylation is known to play an important role in transcriptional regulation of proinflammatory genes. The aim of this study was to investigate the molecular mechanism(s) of inflammatory responses caused by cigarette smoke extract (CSE) in the human macrophage-like cell line MonoMac6 and whether the treatment of these cells with the antioxidant glutathione (GSH) monoethyl ester, or modulation of the thioredoxin redox system, can attenuate cigarette smoke-mediated IL-8 release. Exposure of MonoMac6 cells to CSE (1% and 2.5%) increased IL-8 and TNF-α production vs. control at 24 h and was associated with significant depletion of GSH levels associated with increased reactive oxygen species release in addition to activation of NF-κB. Inhibition of IKK ablated the CSE-mediated IL-8 release, suggesting that this process is dependent on the NF-κB pathway. CSE also reduced histone deacetylase (HDAC) activity and HDAC1, HDAC2, and HDAC3 protein levels. This was associated with posttranslational modification of HDAC1, HDAC2, and HDAC3 protein by nitrotyrosine and aldehyde-adduct formation. Pretreatment of cells with GSH monoethyl ester, but not thioredoxin/thioredoxin reductase, reversed cigarette smoke-induced reduction in HDAC levels and significantly inhibited IL-8 release. Thus cigarette smoke-induced release of IL-8 is associated with activation of NF-κB via IKK and reduction in HDAC levels/activity in macrophages. Moreover, cigarette smoke-mediated proinflammatory events are regulated by the redox status of the cells.

Targeting histone deacetylase 2 in chronic obstructive pulmonary disease treatment

There is increasing evidence that histone acetylation plays a critical role in the regulation of inflammatory genes and in mediating the anti-inflammatory effects of corticosteroids. Inflammatory stimuli through transcription factors, such as NF-kappaB, recruit co-activator molecules with intrinsic histone acetyltransferase activity, leading to hyperacetylation of core histones and gene activation. Histone deacetylases (HDACs) reverse this process and suppress inflammatory genes. Corticosteroids, the most effective anti-inflammatory drugs so far available, recruit HDAC2 to activated inflammatory gene complexes through an interaction with glucocorticoid receptor and thus switch off activated inflammatory genes. In chronic obstructive pulmonary disease and in asthmatic patients who smoke, there is a reduction in HDAC2 activity and expression, resulting in amplification of inflammation and corticosteroid resistance. Therapeutic strategies to increase HDAC activity may, therefore, be expected to reduce inflammation and restore steroid responsiveness. These strategies include low doses of theophylline or antioxidants and nitric oxide synthase inhibitors. HDACs may be inhibited directly by siRNA and in the future by small-molecule activators may be discovered through high output screening. These drugs may represent a novel approach to treating chronic inflammatory diseases.

Free radical theory of autoimmunity

Background

Despite great advances in clinical oncology, the molecular mechanisms underlying the failure of chemotherapeutic intervention in treating lymphoproliferative and related disorders are not well understood.

Hypothesis

A hypothetical scheme to explain the damage induced by chemotherapy and associated chronic oxidative stress is proposed on the basis of published literature, experimental data and anecdotal observations. Brief accounts of multidrug resistance, lymphoid malignancy, the cellular and molecular basis of autoimmunity and chronic oxidative stress are assembled to form a basis for the hypothesis and to indicate the likelihood that it is valid in vivo.

Conclusion

The argument set forward in this article suggests a possible mechanism for the development of autoimmunity. According to this view, the various sorts of damage induced by chemotherapy have a role in the pattern of drug resistance, which is associated with the initiation of autoimmunity.

Radiation and the regulatory landscape of neo2-Darwinism

Several recently revealed features of eukaryotic genomes were not predicted by earlier evolutionary paradigms, including the relatively small number of genes, the very large amounts of non-functional code and its quarantine in heterochromatin, the remarkable conservation of many functionally important genes across relatively enormous phylogenetic distances, and the prevalence of extra-genomic information associated with chromatin structure and histone proteins. All of these emphasize a paramount role for regulatory evolution, which is further reinforced by recent perspectives highlighting even higher-order regulation governing epigenetics and development (EVO-DEVO). Modern neo2-Darwinism, with its emphasis on regulatory mechanisms and regulatory evolution provides new vision for understanding radiation biology, particularly because free radicals and redox states are central to many regulatory mechanisms and free radicals generated by radiation mimic and amplify endogenous signalling. This paper explores some of these aspects and their implications for low-dose radiation biology.

DATS reduces LPS-induced iNOS expression, NO production, oxidative stress, and NF-kappaB activation in RAW 264.7 macrophages

Diallyl trisulfide (DATS), diallyl sulfide (DAS), and diallyl disulfide (DADS) are the three major organosulfur compounds (OSCs) in garlic oil. In contrast to DADS and DATS, evidence of an anti-inflammatory effect of DATS is limited. In this study compares the efficacy of DATS with those of DAS and DADS on lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in RAW 264.7 macrophages. The NO production in LPS-activated RAW 264.7 macrophages was suppressed by both DADS and DATS in a dose-dependent manner. At 100 muM, the nitrite levels of DADS- and DATS-treated cells were 57 and 34%, respectively, of cells treated with LPS alone. DAS, however, had no influence on NO production even at a concentration of 1 mM. Western blot and Northern blot assays showed that DADS and DATS but not DAS dose-dependently suppressed LPS-induced iNOS protein and mRNA expression in a pattern similar to that noted for NO production. LPS-induced cellular peroxide production was significantly inhibited by DADS and DATS (P < 0.05) but not by DAS. Electrophoresis mobility shift assays further indicated that DADS and DATS effectively inhibited the activation of NF-kappaB induced by LPS. Taken together, these results indicate that the differential efficacy of three major OSCs of garlic oil on suppression of iNOS expression and NO production is related to the number of sulfur atoms and is in the order DATS > DADS > DAS. The inhibitory effect of DATS on LPS-induced iNOS expression is likely attributed to its antioxidant potential to inhibit NF-kappaB activation.

Thrombin-induced caspases 3 and 9 translocation to the cytoskeleton is independent of changes in cytosolic calcium in human platelets

Apoptosis has been shown to be associated with changes in cytosolic free calcium concentration ([Ca(2+)](c)). Here we show that the agonist thrombin induces activation of caspases 9 and 3 and translocation of the caspase active forms and procaspases to the cytoskeleton in human platelets. Dimethyl-BAPTA loading did not affect thrombin-induced caspase 9 and 3 activation or translocation suggesting that these responses are independent of increases in [Ca(2+)](c). Treatment with thapsigargin plus ionomycin, to induce extensive Ca(2+) store depletion and subsequent increase in [Ca(2+)](c), stimulates caspase activation although it was unable to induce caspase translocation to the cytoskeleton. Similar results were observed in cells loaded with dimethyl-BAPTA, suggesting that activation of caspases 9 and 3 by thapsigargin plus ionomycin does not require rises in [Ca(2+)](c). These findings suggest that thrombin-induced caspase 9 and 3 activation and translocation are independent on rises in [Ca(2+)](c) but might require store depletion in human platelets.

An assessment of the role of reactive oxygen species and redox signaling in norepinephrine-induced apoptosis and hypertrophy of H9c2 cardiac myoblasts

Cardiac myocytes, upon exposure to increasing doses of norepinephrine (NE), transit from hypertrophic to apoptotic phenotype. Since reactive oxygen species (ROS) generation is attributed to both phenomena, the authors tested whether an elevation in intracellular ROS level causes such transition. H9c2 cardiac myoblasts upon treatment with hypertrophic and apoptotic doses of NE (2 and 100 microM, respectively) transiently induced intracellular ROS at a comparable level, while 200 microM H(2)O(2), another proapoptotic agonist, showed robust and sustained ROS generation. Upon analysis of a number of redox-responsive transcription factors as the downstream targets of ROS signaling, the authors observed that NE (2 and 100 microM) and H(2)O(2) (200 microM) were ineffective in inducing NF-kappaB while both the agonists upregulated AP-1 and Nrf-2. However, the extents of induction of AP-1 and Nrf-2 were not in direct correlation with the respective ROS levels. Also, AP-1 activities induced by two doses of NE were intrinsically different, since at 2 microM, it primarily induced FosB, and at 100 microM it activated Fra-1. Differential induction of FosB and Fra-1 was also reiterated in adult rat myocardium injected with increasing doses of NE. Therefore, NE induces hypertrophy and apoptosis in cardiac myocytes by distinct redox-signaling rather than a general surge of ROS.

NF-kappaB activation by reactive oxygen species: fifteen years later

The transcription factor NF-kappaB plays a major role in coordinating innate and adaptative immunity, cellular proliferation, apoptosis and development. Since the discovery in 1991 that NF-kappaB may be activated by H(2)O(2), several laboratories have put a considerable effort into dissecting the molecular mechanisms underlying this activation. Whereas early studies revealed an atypical mechanism of activation, leading to IkappaBalpha Y42 phosphorylation independently of IkappaB kinase (IKK), recent findings suggest that H(2)O(2) activates NF-kappaB mainly through the classical IKK-dependent pathway. The molecular mechanisms leading to IKK activation are, however, cell-type specific and will be presented here. In this review, we also describe the effect of other ROS (HOCl and (1)O(2)) and reactive nitrogen species on NF-kappaB activation. Finally, we critically review the recent data highlighting the role of ROS in NF-kappaB activation by proinflammatory cytokines (TNF-alpha and IL-1beta) and lipopolysaccharide (LPS), two major components of innate immunity.

Effects of polyphenols on human Th1 and Th2 cytokine production

BACKGROUND

Numerous phenolic compounds are consumed in the diet in a range of foods. There are very few studies of the effects of these compounds on the production of lymphocyte-derived cytokines.

AIM OF THE STUDY

To investigate the effects of five phenolic compounds on cytokine production by cultured human lymphocytes.

METHODS

Human whole blood cultures were stimulated with the T cell stimulant concanavalin A for 48 h in the presence of phenolic compounds (vanillic acid, syringic acid, kaempferol, oleuropein and tyrosol) at concentrations up to 10(-4) M. Interleukin (IL)-2, IL-4 and interferon-gamma (IFN-gamma) concentrations were measured in the culture supernatants by ELISA.

RESULTS

IFN-gamma concentration was significantly lower in cultures containing 10(-4) M kaempferol than in cultures with kaempferol at 10(-7), 10(-6)and 10(-5) M or without kaempferol. The other phenolic compounds did not affect IFN-gamma concentration and none of the phenolics tested affected IL-2 or IL-4 concentrations.

CONCLUSIONS

Some, but not all, phenolic compounds can decrease IFN-gamma production by stimulated human whole blood cultures.

Cardiac histones are substrates of histone deacetylase activity in hemorrhagic shock and resuscitation

BACKGROUND

DNA transcription is regulated, in part, by acetylation of nuclear histones that are controlled by 2 groups of enzymes: histone deacetylases (HDAC) and histone acetyl transferases (HAT). Whether an imbalance in HDAC/HAT system plays a role in hemorrhage/resuscitation is unknown. The goals of this study were to determine whether hemorrhage results in deacetylation of cardiac histones and whether this can be corrected through the application of different resuscitation strategies or specific HDAC inhibitors.

METHODS

In the first experiment, rats (n = 6 per group) were subjected to volume-controlled hemorrhage and resuscitated with racemic lactated Ringer's solution, L-lactated Ringer's solution, 7.5% hypertonic saline solution, ketone Ringer's solution, and pyruvate Ringer's solution. Control groups included no hemorrhage (sham) and hemorrhage with no resuscitation. In the second experiment (n = 5 per group), 3 HDAC inhibitors (valproic acid, trichostatin A, and suberoylanilide hydroxamic acid) were added to saline solution resuscitation. Heart tissue was collected at the end of resuscitation. Isolated subcellular protein fractions were used in Western blotting to analyze the patterns of total protein acetylation and histone acetylation specifically. HDAC and HAT activity was measured in tissue extracts.

RESULTS

Hemorrhage led to partial histone deacetylation. Resuscitation resulted in protein hyperacetylation in nuclear fractions only. A detailed analysis of histones (on 10 acetylation sites) revealed that ketone Ringer's solution hyperacetylated histones H2B, H3, and H4. The addition of suberoylanilide hydroxamic acid hyperacetylated histones more effectively than other resuscitation strategies, presumably by direct inhibition of HDAC activity.

CONCLUSION

Hemorrhage/resuscitation is associated with HDAC/HAT activity misbalance, and the acetylation status of cardiac histones is influenced by the choice of resuscitation strategy. Shock-induced changes can be reversed through the infusion of pharmacologic HDAC inhibitor, even when it is administered after the insult for a limited period of time.

Reduced histone deacetylase in COPD: clinical implications

COPD is characterized by progressive inflammation in the small airways and lung parenchyma, and this is mediated by the increased expression of multiple inflammatory genes. The increased expression of inflammatory genes is regulated by acetylation of core histones around which DNA is wound, and conversely these activated genes are switched off by deacetylation of these histones. Histone deacetylases (HDACs) suppress inflammatory gene expression, but their activity and expression (particularly of HDAC-2) is reduced in the peripheral lung and in alveolar macrophages of patients with COPD. This results in amplification of the inflammatory response as COPD progresses but also accounts for corticosteroid resistance in COPD, since HDAC-2 is required by corticosteroids to switch off activated inflammatory genes. The reduction in HDAC-2 appears to be secondary to the increased oxidative and nitrative stress in COPD lungs. Antioxidants and inhibitors of nitric oxide synthesis may therefore restore corticosteroid sensitivity in COPD, but this can also be achieved by low doses of theophylline, which is an HDAC activator. This mechanism is also relevant to asthmatic patients who smoke, patients with severe asthma and cystic fibrosis, in whom oxidative stress is also increased.

Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed.

Protein oxidation by chronic pulmonary diseases in children

The oxidation of proteins may play an important role in the pathogenesis of chronic inflammatory lung diseases, and may contribute to lung damage. However, the extent of oxidation and the distribution among proteins are not known for most pediatric lung diseases. In this work, protein oxidation was assessed as protein carbonyls. Bronchoalveolar lavages (BAL) from children with chronic lung diseases were investigated by dot-blot assay for content and for pattern of distribution of oxidized proteins by two-dimensional (2D) electrophoresis and Western blotting. Significantly higher levels of protein oxidation than in healthy controls were determined in groups of patients with interstitial lung disease, gastro-esophageal reflux disease, and pulmonary alveolar proteinosis. The proteins most sensitive to oxidation were serum albumin, surfactant protein A, and alpha1-antitrypsin. Our data show increased oxidative stress in lungs of children with chronic pulmonary diseases, with significant interindividual variations. The extent of protein oxidation was proportional to the count of neutrophilic granulocytes in BAL fluid. These findings strongly support the concept that an abundance of reactive oxygen species produced during neutrophilic inflammation may be a deleterious factor, leading to pulmonary damage in these patients.

The Effect of Cigarette Smoke-derived Oxidants on the Inflammatory Response of the Lung

The inhalation of cigarette smoke triggers a marked cellular influx in the lung and this inflammation is believed to play a central role in the development of smoke-related lung diseases such as asthma and COPD. Studies demonstrate that smoke-derived oxidants are a major factor in this inflammatory reaction to cigarette smoke. These oxidants can overwhelm the lung's antioxidant defenses and they can up regulate inflammation by a number of mechanisms. Free radicals directly stimulate the production of chemotactic compounds such as 8-isoprostane. In addition, smoke-derived oxidants can activate several intracellular signaling cascades including NF-κB, MAPK and AP-1. This transcriptional activation induces the expression of cytokines and intracellular adhesion molecules that facilitates the trafficking of neutrophils, macrophages and lymphocytes into the lung. Moreover, oxidants can promote chromatin remodeling that facilitates the expression of proinflammatory genes by stimulating the acetylation of histone residues in the nucleosome. This leads to conformational changes that enhance expression by rendering the gene more accessible to binding to transcriptional factors. Thus, the oxidant-antioxidant imbalance generated by cigarette smoke can promote inflammation which is critical to the functional decline that occurs in both asthma and COPD patients. Future research is needed to better define the effects of smoke-derived oxidants on lung inflammation and to determine the most efficacious strategies for generating significant antioxidant protection in the lung.

Reactive oxygen species and related haem pathway components as possible epigenetic modifiers in neurobehavioural pathology

The neuroendocrine response to stress utilizes several bio-communicative pathways which also play a role in neurodevelopmental plasticity. The mechanism of action of steroidal compounds includes DNA alteration by reactive oxygen species (ROS) arising through redox cycling of reactive hormone derivatives. ROS and reactive nitrogen species play a significant role in signaling networks affecting gene transcriptional regulation during normal as well as stress-induced responses. ROS-associated synaptic and regulatory region plasticity may have been important for normal brain evolution, but probably simultaneously lowered the threshold for inducing neuropathology. A shift from 'plasticity' to 'instability' is likely to be associated with the emergence of complex effects depending on the timing, duration and intensity of the ROS insult, and is suggested to include heritable epigenetic chromatin/regulatory region remodeling differentially influencing expression levels of significant neuropsychiatric genes and their variant alleles. Neurobehavioural disorder clinical manifestations have been linked with ROS effects. The concepts discussed here relate to ROS-associated instability of DNA regulatory region sequences and a proposal that it may play an important modifying role in brain and neuro-behaviourally related gene expression. Genes encoding key steps in mitochondrial, haem, iron and bilirubin ROS metabolic pathways have been used as examples to illustrate how ROS-modified regulatory networks could possibly alter the context within which (even ostensibly unrelated) neuropsychiatric gene candidates may sometimes be recruited. Furthermore, reactions of certain radicals release sufficient energy to generate UV-photons. DNA conformational changes accompanied by changes in photon emission suggest that functional neuroimaging findings probably reflect interaction on the level of ROS/biophoton/genome regulatory region domains rather than the signatures of individual neurobehavioural disorder candidate genes.

Nuclear factor-kappa B nuclear translocation in the cochlea of mice following acoustic overstimulation

There is increasing evidence to suggest that the expression of many molecules in the lateral wall of the cochlea plays an important role in noise-induced stress responses. In this study, activation of the nuclear transcription factor nuclear factor-kappa B (NF-kappaB) was investigated in the cochlea of mice treated with intense noise exposure (4 kHz, octave band, 124 dB, for 2 h). The present noise exposure led to remarkable auditory brainstem response threshold shifts and cochlear damage on surface preparations. To assess the effects of noise exposure on NF-kappaB/DNA binding activity in the cochlea, we prepared nuclear extracts from the cochlea at different time points after noise exposure and carried out an electrophoretic mobility shift assay using a probe specific to NF-kappaB. NF-kappaB/DNA binding was significantly enhanced in the cochlea 2-6 h after noise exposure and returned to basal levels after 12 h. Supershift analysis using antibodies against p65 and p50 proteins, which are components of NF-kappaB, demonstrated that enhancement of NF-kappaB/DNA binding was at least in part due to nuclear translocation of p65. An immunohistochemical study also showed that nuclear translocation of both p65 and p50 was observed in the lateral wall after noise exposure and that there may be a possible close association between p65 and enhanced inducible nitric oxide synthase expression. These results suggest that NF-kappaB may have a detrimental role in the response to acoustic overstimulation in the cochlea of mice.

Redox modifications of protein-thiols: emerging roles in cell signaling

Glutathione represents the major low molecular weight antioxidant redox recycling thiol in mammalian cells and plays a central role in the cellular defence against oxidative damage. Classically glutathione has been known to provide the cell with a reducing environment in addition to maintaining the proteins in a reduced state. Emerging evidences suggest that the glutathione redox status may entail dynamic regulation of protein function by reversible disulfide bond formation. The formation of inter- and intramolecular disulfides as well as mixed disulfides between protein cysteines and glutathione, i.e., S-glutathiolation, has now been associated with the stabilization of extracellular proteins, protection of proteins against irreversible oxidation of critical cysteine residues, and regulation of enzyme functions and transcription. Regulation of DNA binding of redox-dependent transcription factors such as nuclear factor-kappaB, p53, and activator protein-1, has been suggested as one of the mechanisms by which cells may transduce oxidative stress redox signaling into an inducible expression of a wide variety of genes implicated in cellular changes such as proliferation, differentiation, and apoptosis. However, the molecular mechanisms linking the glutathione cellular redox state to a reversible oxidation of various signaling proteins are still poorly understood. This commentary discusses the emerging concept of protein-S-thiolation, protein-S-nitrosation and protein-SH (formation of sulfenic, sulfinic and sulfonic acids) in redox signaling during normal physiology and under oxidative stress in controlling the cellular processes.

TWEAK Attenuates the Transition from Innate to Adaptive Immunity

Innate immunity is the first line of defense against infection, protecting the host during the development of adaptive immunity and critically affecting the nature of the adaptive response. We show that, in contrast to tumor necrosis factor alpha (TNF-alpha), the related protein TWEAK attenuates the transition from innate to adaptive mechanisms. TWEAK-/- mice had overabundant natural killer (NK) cells and displayed hypersensitivity to bacterial endotoxin, with their innate immune cells producing excess interferon (IFN)-gamma and interleukin (IL)-12. TWEAK inhibited stimulation of the transcriptional activator STAT-1 and induced p65 nuclear factor (NF)-kappaB association with histone deacetylase 1, repressing cytokine production. TWEAK-/- mice developed oversized spleens with expanded memory and T helper 1 (TH1) subtype cells upon aging and mounted stronger innate and adaptive TH1-based responses against tumor challenge. Thus, TWEAK suppresses production of IFN-gamma and IL-12, curtailing the innate response and its transition to adaptive TH1 immunity.

Redox-sensitive transcription factors as prime targets for chemoprevention with anti-inflammatory and antioxidative phytochemicals

Oxidative stress has been implicated in various pathological conditions including cancer. However, the human body has an intrinsic ability to fight against oxidative stress. A wide array of phase 2 detoxifying or antioxidant enzymes constitutes a fundamental cellular defense system against oxidative and electrophilic insults. Transcriptional activation of genes encoding detoxifying and antioxidant enzymes by NF-E2 related factor 2 (Nrf2), a member of the cap'n'collar family of basic leucine zipper transcription factors, may protect cells and tissues from oxidative damage. Many chemopreventive and chemoprotective phytochemicals have been found to enhance cellular antioxidant capacity through activation of this particular transcription factor, thereby blocking initiation of carcinogenesis. A new horizon in chemoprevention research is the recent discovery of molecular links between inflammation and cancer. Components of the cell signaling pathways, especially those that converge on redox-sensitive transcription factors, including nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) involved in mediating inflammatory response, have been implicated in carcinogenesis. A wide variety of chemopreventive and chemoprotective agents can alter or correct undesired cellular functions caused by abnormal proinflammatory signal transmission mediated by inappropriately activated NF-kappaB and AP-1. The modulation of cellular signaling by anti-inflammatory phytochemicals hence provides a rational and pragmatic strategy for molecular target-based chemoprevention.

Androgen receptor and NFkB expression in human normal and glaucomatous optic nerve head astrocytes in vitro and in experimental glaucoma

For several decades, clinical and experimental observations suggested a relationship between steroids and glaucoma; however, the possibility that androgens are also involved in the glaucomatous changes in the optic nerve heads (ONH) has not been explored. Our previous findings that glaucomatous ONH astrocytes synthesize androgen-metabolising enzymes and overproduce a neuroactive androgen, 5alpha-androstane-3alpha, 17beta-diol (3alpha-diol) led us to propose that ONH astrocytes are androgen target cells. Androgens modulate different cellular processes through androgen receptor (AR). NFkB is a transcription factor that positively regulates AR transcription. Here, we analysed AR and NFkB expression in normal and glaucomatous ONH astrocytes in vitro, and in vivo in a monkey model of experimental glaucoma (ExpG) by quantitative real time RT-PCR, Western blotting and immunohistochemistry. We demonstrated that in vitro human glaucomatous ONH astrocytes express AR mRNA and protein at higher levels than normal astrocytes and that in vivo ONH astrocytes from eyes with ExpG showed increased nuclear and cytoplasmic AR immunostaining compared to control eyes. In the retina, retinal ganglion cells (RGC) demonstrated cytoplasmic staining both in control and in ExpG eyes. NFkB mRNA expression was higher in glaucomatous ONH astrocytes than in normal and more nuclear NFkB protein was detected in glaucomatous ONH astrocytes. In vivo immunopositive NFkB nuclear staining of ONH astrocytes in ONH and in RGC in retina was detected both in control and in ExpG eyes. We conclude that in addition to our published data, increase of AR and NFkB expression in glaucomatous ONH astrocytes provides strong evidence that androgens play a significant role in the pathophysiology of glaucoma.

Role of Rac-GTPase and reactive oxygen species in cardiac differentiation of stem cells

In the life of a cell, there is a constant balance between generation of reactive oxygen species (ROS) and activity of antioxidant defense mechanisms. Besides the damaging effects of ROS on many biomolecules, ROS also play a significant role in signal transduction pathways of growth factors suggesting a role of oxidative species in cell differentiation. ROS have recently been involved in the process of cardiac differentiation of stem cells. Several molecular mechanisms, including ones mediated by the GTPase Rac that underlie the regulatory role of ROS in the process of stem cell differentiation toward a cardiac lineage, are reviewed.

Steroid-resistant Inflammation in a Rat Model of Chronic Obstructive Pulmonary Disease Is Associated with a Lack of Nuclear Factor-κB Pathway Activation

RATIONALE

Emphysema is one component of chronic obstructive pulmonary disease (COPD), a respiratory disease currently increasing in prevalence worldwide. The mainstay therapy adopted to treat patients with COPD is glucocorticoids; unfortunately, this treatment has limited impact on disease symptoms or underlying airway inflammation.

OBJECTIVE

There is an urgent need to develop therapies that modify both the underlying inflammation, thought to be involved in disease progression, and the structural changes in the emphysematous lung.

METHODS

We have characterized an elastase-driven model of experimental emphysema in the rat that demonstrates COPD-like airway inflammation and determined the impact of a clinically relevant glucocorticoid.

MEASUREMENTS AND MAIN RESULTS

We observed an increase in lung neutrophils, lymphomononuclear cells, mucus production, and inflammatory cytokines. Also present were increases in average air space area, which are associated with emphysema-like changes in lung function, such as increased residual volume and decreased flow; these increases in area were maintained for up to 10 weeks. In addition, we observed that elastase-induced airway neutrophilia is steroid resistant. Interestingly, the inflammation observed after elastase administration was found to be temporally associated with a lack of nuclear factor-kappaB pathway activation. This apparent nuclear factor-kappaB-independent inflammation may explain why treatment with a glucocorticoid was ineffective in this preclinical model and could suggest parallels in the steroid-resistant human disease.

CONCLUSION

We believe that this model, in addition to its suitability for testing therapies that may modify existing emphysema, could be useful in the search for new therapies to reduce the steroid-resistant airway inflammation evident in COPD.

JNK activation limits dendritic cell maturation in response to reactive oxygen species by the induction of apoptosis

Dendritic cells (DC) sense infection in their local microenvironment and respond appropriately in order to induce T cell immunity. This response is mediated in part via the mitogen-activated protein kinase (MAPK) pathways. Hydrogen peroxide is present frequently in the inflammatory DC milieu and is known to activate MAPK. Therefore this study examines the role of hydrogen peroxide, both alone and in combination with lipopolysaccharide (LPS), in the regulation of activation of two key MAPK, p38 and JNK, regulation of phenotype, and regulation of apoptosis in human monocyte-derived DC. At low concentrations, hydrogen peroxide activates p38, but does not alter DC phenotype. At higher concentrations, hydrogen peroxide activates both p38 and JNK. Activation of JNK, which is associated with inhibition of tyrosine phosphatases in DC, is linked to the induction of DC apoptosis. An upstream JNK inhibitor (CEP11004) and a competitive JNK inhibitor (SP600125) both partially protected the DC from the proapoptotic effects of hydrogen peroxide. Unexpectedly, hydrogen peroxide and LPS synergize in inducing JNK activation and DC apoptosis. JNK-mediated apoptosis may limit damaging immune responses against neoepitopes generated by modification of self-antigens by reactive oxygen species present at sites of inflammation.

Riboflavin deficiency causes protein and DNA damage in HepG2 cells, triggering arrest in G1 phase of the cell cycle

Eukaryotes convert riboflavin to flavin adenine dinucleotide, which serves as a coenzyme for glutathione reductase and other enzymes. Glutathione reductase mediates the regeneration of reduced glutathione, which plays an important role in scavenging free radicals and reactive oxygen species. Here we tested the hypothesis that riboflavin deficiency decreases glutathione reductase activity in HepG2 liver cells, causing oxidative damage to proteins and DNA, and cell cycle arrest. As a secondary goal, we determined whether riboflavin deficiency is associated with gene expression patterns indicating cell stress. Cells were cultured in riboflavin-deficient and riboflavin-supplemented media for 4 days. Activity of glutathione reductase was not detectable in cells cultured in riboflavin-deficient medium. Riboflavin deficiency was associated with an increase in the abundance of damaged (carbonylated) proteins and with increased incidence of DNA strand breaks. Damage to proteins and DNA was paralleled by increased abundance of the stress-related transcription factor GADD153. Riboflavin-deficient cells arrested in G1 phase of the cell cycle. Moreover, oxidative stress caused by riboflavin deficiency was associated with increased expression of clusters of genes that play roles in cell stress and apoptosis. For example, the abundance of the pro-apoptotic pleiomorphic adenoma gene-like 1 gene was 183% greater in riboflavin-deficient cells compared with riboflavin-sufficient controls. We conclude that riboflavin deficiency is associated with oxidative damage to proteins and DNA in liver cells, leading to cell stress and G1 phase arrest.

Increase of intracellular glutathione by low-level NO mediated by transcription factor NF-κB in RAW 264.7 cells

The mechanism underlying the elevation of intracellular glutathione (GSH) in RAW 264.7 cells exposed to low concentrations of sodium nitroprusside (SNP), a well-known nitric oxide (NO) donor, was investigated. The peak of intracellular GSH was reached at 6 h after exposure of the cells to SNP (0.1-0.5 mM), and this was preceded by the induction of mRNA for gamma-glutamylcysteine synthetase (gamma-GCS; the rate-limiting enzyme of de novo GSH synthesis), which peaked at 3 h. N-alpha-Tosyl-L-phenylalanine chloromethyl ketone (TPCK) and caffeic acid phenethyl ester (CAPE), specific inhibitors of NF-kappaB, significantly suppressed the SNP-induced elevation of GSH protein and gamma-GCS mRNA, while curcumin, an inhibitor of AP-1, was less effective. Electrophoretic mobility shift assay (EMSA) showed that SNP exposure markedly increased the DNA binding of NF-kappaB, but not that of AP-1. Deletion or mutagenesis of the NF-kappaB site in the gamma-GCS gene promoter abolished the SNP-induced up-regulation of GSH protein and gamma-GCS mRNA. These results suggest that the elevation of intracellular GSH in RAW 264.7 cells exposed to low concentrations of SNP occurs through the operation of the de novo GSH pathway, and is mediated by transcriptional up-regulation of the gamma-GCS gene, predominantly at the NF-kappaB binding site in its promoter.

Macrophages overexpressing tartrate-resistant acid phosphatase show altered profile of free radical production and enhanced capacity of bacterial killing

Activated macrophages and osteoclasts express high amounts of tartrate-resistant acid phosphatase (TRACP, acp5). TRACP has a binuclear iron center with a redox-active iron that has been shown to catalyze the formation of reactive oxygen species (ROS) by Fenton's reaction. Previous studies suggest that ROS generated by TRACP may participate in degradation of endocytosed bone matrix products in resorbing osteoclasts and degradation of foreign compounds during antigen presentation in activated macrophages. Here we have compared free radical production in macrophages of TRACP overexpressing (TRACP+) and wild-type (WT) mice. TRACP overexpression increased both ROS levels and superoxide production. Nitric oxide production was increased in activated macrophages of WT mice, but not in TRACP+ mice. Macrophages from TRACP+ mice showed increased capacity of bacterial killing. Recombinant TRACP enzyme was capable of bacterial killing in the presence of hydrogen peroxide. These results suggest that TRACP has an important biological function in immune defense system.

Curcumin-induced histone hypoacetylation: The role of reactive oxygen species

Curcumin (Cur), a well-known dietary pigment derived from Curcuma longa, is a promising anticancer drug, but its in vivo target molecules remain to be clarified. Here we report that exposure of human hepatoma cells to Cur led to a significant decrease of histone acetylation. Histone acetyltransferase (HAT) and histone deacetylase (HDAC) are the enzymes controlling the state of histone acetylation in vivo. Cur treatment resulted in a comparable inhibition of histone acetylation in the absence or presence of trichostatin A (the specific HDAC inhibitor), and showed no effect on the in vitro activity of HDAC. In contrast, the domain negative of p300 (a most potent HAT protein) could block the inhibition of Cur on histone acetylation; and the Cur treatment significantly inhibited the HAT activity both in vivo and in vitro. Thus, it is HAT, but not HDAC that is involved in Cur-induced histone hypoacetylation. At the same time, exposure of cells to low or high concentrations of Cur diminished or enhanced the ROS generation, respectively. And the promotion of ROS was obviously involved in Cur-induced histone hypoacetylation, since Cur-caused histone acetylation and HAT activity decrease could be markedly diminished by the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) or their combination, but not by their heat-inactivated forms. The data presented here prove that HAT is one of the in vivo target molecules of Cur; through inhibiting its activity, Cur induces histone hypoacetylation in vivo, where the ROS generation plays an important role. Considering the critical roles of histone acetylation in eukaryotic gene transcription and the involvement of histone hypoacetylation in the lose of cell viability caused by high concentrations of Cur, these results open a new door for us to further understand the molecular mechanism involved in the in vivo function of Cur.

The Role of Oxidative Stress in the Pathogenesis??of COPD

Chronic inflammation and oxidative stress are important features in the pathogenesis of COPD. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. Oxidative stress has important implications on several events of lung physiology and for the pathogenesis of COPD. These include oxidative inactivation of antiproteases and surfactants, mucus hypersecretion, membrane lipid peroxidation, mitochondrial respiration, alveolar epithelial injury, remodeling of extracellular matrix, and apoptosis. An increased level of ROS produced in the airways is reflected by increased markers of oxidative stress in the airspaces, sputum, breath, lungs, and blood in patients with COPD. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde and 4-hydroxy-2-nonenal have been successfully measured in breath condensate. ROS and aldehydes play a key role in enhancing the inflammation through the activation of mitogen-activated protein kinases and redox-sensitive transcription factors such as nuclear factor kappa B and activator protein-1. Oxidative stress also alters nuclear histone acetylation and deacetylation leading to increased gene expression of pro-inflammatory mediators in the lung. Oxidative stress may play a role in the poor clinical efficacy of corticosteroids in the treatment of COPD. Since a variety of oxidants, free radicals, and aldehydes are implicated in the pathogenesis of COPD it is likely that a combination of antioxidants may be effective in the treatment of COPD. Antioxidant compounds may also be of therapeutic value in monitoring oxidative biomarkers indicating disease progression. Various approaches to enhance the lung antioxidant screen and the clinical effectiveness of antioxidant compounds in the treatment of COPD are discussed.