A large body of evidence suggests that mitochondrial dysfunction and oxidative damage play a role in the pathogenesis of Parkinson's disease (PD). A number of antioxidants have been effective in animal models of PD. We have developed a family of mitochondria-targeted peptides that can protect against mitochondrial swelling and apoptosis (SS peptides). In this study, we examined the ability of two peptides, SS-31 and SS-20, to protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity in mice. SS-31 produced dose-dependent complete protection against loss of dopamine and its metabolites in striatum, as well as loss of tyrosine hydroxylase immunoreactive neurons in substantia nigra pars compacta. SS-20, which does not possess intrinsic ability in scavenging reactive oxygen species, also demonstrated significant neuroprotective effects on dopaminergic neurons of MPTP-treated mice. Both SS-31 and SS-20 were very potent (nM) in preventing MPP+ (1-methyl-4-phenylpyridinium)-induced cell death in cultured dopamine cells (SN4741). Studies with isolated mitochondria showed that both SS-31 and SS-20 prevented MPP+-induced inhibition of oxygen consumption and ATP production, and mitochondrial swelling. These findings provide strong evidence that these neuroprotective peptides, which target both mitochondrial dysfunction and oxidative damage, are a promising approach for the treatment of PD.
We show that 1-methyl-4-phenylpyridinium ion (MPP(+)), an active metabolite of 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP), induces cytotoxicity via endoplasmic reticulum (ER)- and mitochondria-mediated pathways, and thioredoxin-1 (TRX-1), a redox-active protein, prevents MPTP-induced neurotoxicity. TRX-1 overexpression suppressed reactive oxygen species and the ATP decline caused by MPP(+) in HepG2 cells. MPP(+) activated caspase-12 in PC12 cells and induced cytotoxicity in HeLa-rho(0) cells lacking mitochondrial DNA, as well as in the parental HeLa-S3 cells. TRX-1-transgenic mice demonstrated significant resistance to caspase-12 activation and the apoptotic decrease of dopaminergic neurons after MPTP administration, compared with wild-type C57BL/6 mice.
The optimized geometry of 1,5-dihydrolumiflavin has been calculated using density functional theory (DFT). Reduced lumiflavin was found to be bent along the N5-N10 axis, 25 degrees from planarity, which is nearly the same as previously reported restricted Hartree-Fock (RHF) calculations, which predict a bending angle of 27 degrees. The major difference in the DFT calculation is that the N10 methyl group adopts a more pseudoequatorial disposition and is only bent 13 degrees above the plane of the isoalloxazine ring system as opposed to 59 degrees in the RHF calculations. These computational results are compared with x-ray crystal structures of flavin models and flavoproteins. DFT calculation of 1,5-dihydroisoalloxazine resulted in a more modestly bent geometry of 17 degrees. This indicates that both electronic and steric interactions of the N10 methyl group of reduced lumiflavin contribute to the bent geometry.
The corresponding author has sought retraction of this work from ARS. The author statement is copied below: We, the authors, wish to retract "Cigarette Smoke-induced Oxidative/Nitrosative Stress Impairs VEGF- and Fluid Shear Stress-Mediated Signaling in Endothelial Cells" by Edirisinghe et al (Antioxid Redox Signal, 12(12): 1355-1369. doi:10.1089/ars.2009.2874) because we are not satisfied with the quality of some of the data presented in the paper. Overall, however, the data are reproducible and the conclusions drawn were not affected. We apologize for any inconvenience this may have caused to the readers.
The human leukocyte antigen (HLA)-B27 is strongly associated with a group of inflammatory arthritic disorders known as the spondyloarthropathies (SpAs). The unusual biochemistry of HLA-B27 has been proposed to participate in disease development, especially the enhanced ability of HLA-B27 to form several heavy chain-dimer populations. HLA-B27 possesses three unpaired cysteine (C) residues at position 67, 308, and 325, in addition to the four conserved cysteine residues at p101, 164, 203, and 259. C67 was proposed to participate in dimer formation of recombinant HLA-B27 protein and in vivo heavy chain-dimers. However, the structurally conserved C164 was demonstrated to participate in endoplasmic reticulum (ER) resident heavy chain-dimer formation. We therefore wanted to determine whether these aggregates involve cysteines other than C164 and the basis for the difference between the observed heavy chain-dimer species.
We determined that C164 and C101 can form distinct dimer structures and that the heterogenous nature of heavy chain-dimer species is due to differences in both redox status and conformation. Different HLA-B27 dimer populations can be found in physiologically relevant cell types derived from HLA-B27-positive patients with inflammatory arthritis. In addition, HLA-B27 dimer formation can be correlated with cellular stress induction.
The use of both mutagenesis and manipulating cellular redox environments demonstrates that HLA-B27 dimerization requires both specific cysteine?cysteine interactions and conformations with differing redox states.
HLA-B27 heavy chain-dimerization is a complex process and these findings provide an insight into HLA-B27 misfolding and a potential contribution to inflammatory disease development.
To establish a functional link between microRNA-107 (miR-107) and stem cell survival during ischemic preconditioning (IPC) of stem cells with multiple cycles of brief anoxia/re-oxygenation (10 or 30 min, one to three cycles) and show that the cytoprotective effects were independent of hypoxamir-210.
We demonstrated the induction of miR-107 in response to the IPC-induced activation of Akt/hypoxia inducible factor-1α (HIF-1α) in preconditioned mesenchymal stem cells ((PC)MSC), which showed improved survival during subsequent exposure to 6 h of lethal anoxia (p<0.05 vs. non-preconditioned MSC[(non-PC)MSC]). In silico analysis and luciferase activity assay confirmed programmed cell death-10 (PDCD10) as a putative target of miR-107 in (PC)MSC, which was significantly reduced during IPC and inversely related to stem cell survival under 6 h of lethal anoxia. Loss-of-function studies with miR-107 antagomir showed a significantly reduced survival of (PC)MSC. A comparison of miR-107 and miR-210 showed that both miRs participated independently via their respective putative target genes Pdcd10 and Casp8ap2. The simultaneous abrogation of Pdcd10 and Casp8ap2 had a stronger effect on (PC)MSC survival under lethal anoxia. The transplantation of (PC)MSC in an acute model of myocardial infarction showed a significantly improved survival of transplanted (PC)MSC with concomitantly enhanced miR-107 expression in (PC)MSC-transplanted animal hearts.
Cytoprotection afforded by IPC is regulated by miR-107 induction via Pdcd10 independent of miR-210/Casp8ap2 signaling, and the simultaneous abrogation miR-107/miR-210 has a stronger effect on the loss of (PC)MSC survival.
IPC enhances stem cell survival via the combined participation of hypoxia responsive miRs miR-107 and miR-210 via their respective putative target genes Pdcd10 and Casp8ap2.
Abstract Aims: The fate decision of adult stem cells is determined by the activation of specific intracellular signaling pathways after exposure to specific stimuli. In this study, we demonstrated specific functions of a novel small molecule, CBM-1078, that induced cell self-renewal via Oct4- and canonical Wnt/β-catenin-mediated deaging in cultured human adipose tissue-derived stem cells (hATSCs).
As a potential glycogen synthase kinase-3β (GSK-3β) inhibitor, CBM-1078 primarily activated β-catenin and Oct4 expression after inhibition of GSK-3β. Treatment of hATSCs with CBM-1078 led to transdifferentiation toward a neural precursor cell fate after transient self-renewal, and the cells were capable of differentiation into gamma-Aminobutyric acid (GABA)-secreting neuronal cells with pain-modulating functions in an animal model of neuropathic pain. During cell self-renewal, CBM-1078 directs the translocalization of β-catenin and Oct4 into the nucleus, an event that is crucial for the cooperative activation of hATSC neurogenesis via Oct4 and Wnt/β-catenin. Nuclear-localized β-catenin and Oct4 act together to regulate the expression of Oct4, Nanog, Sox2, β-catenin, c-Myc, and STAT3 after binding to the regulatory regions of these genes. Nuclear Oct4 and Wnt3a/β-catenin also control cell growth by binding to the promoters of STAT3, Gli3, and c-Myc after complex formation and direct interaction. CBM-1078 actively enhanced the DNA-binding affinity of Oct4 and β-catenin to functional genes and activated the Wnt/β-catenin pathway to promote hATSC reprogramming.
Innovation and conclusion:
This study revealed the value of a single small molecule, CBM-1078, showing a definitive cell reprogramming mechanism. Finally, we confirmed the therapeutic potential of GABA-hATSCs for treatment of neuropathic pain, which could be used for therapeutic purposes in humans. Antioxid. Redox Signal. 00, 000-000.
In recent years, it has become clear that balanced regulation of reactive oxygen species is of critical significance for cell-fate determination as well as for stem cell development, function, and survival. Although many questions regarding intracellular redox status regulation of stem cell fate remain, we review here what is known regarding the impact of cell-fate signaling as shown with a variety of human cancer cells and more recently on cancer-initiating cells and on the regenerative capacity of skeletal muscle and hematopoietic tissue and their stem cells. We also discuss the role of altered intracellular redox status as a potential primary pathogenic mechanism in muscular dystrophy and hematopoietic pathologies. Studies discussed here illustrate how understanding altered redox regulation of stem cell behavior may contribute to the development of novel stem cell therapies.
The authors noticed an inaccuracy after recently checking past experimental data in the article "Regulation of heart function by endogenous gaseous mediators-crosstalk between nitric oxide and hydrogen sulfide" by Yong QC, Cheong JL, Hua F, Deng LW, Khoo YM, Lee HS, Perry A, Wood M, Whiteman M, Bian JS. Antioxid Redox Signal. 2011 Jun;14(11):2081-91. The correct version of Fig 3A is provided as part of this erratum publication. The experiment was done together with several nitric oxide (NO) donors, including L-arginine and sodium nitroprusside (SNP). The mistake occurred during manuscript preparation, when the experimental data using SNP as NO donor were erroneously plotted as L-arginine. In this erratum, we replaced Figure 3A with the correct L-arginine data. The representative tracings were also edited to reflect the L-arginine data. The authors would like to stress that only the p-value of L-arg+NaHS group remains significant (p<0.05) when compared against the control. Therefore, the authors claim that these changes do not alter the conclusions of this article. The authors regret this error and apologize for any confusion or inconvenience it may have caused.
Our laboratory has published the first evidence obtained from fast low-angle-shot cine magnetic resonance imaging (11.7 T) studies demonstrating secondary myocyte death after ischemia/reperfusion (IR) of the murine heart. This work provides the first evidence from 11.7-T magnet-assisted pixel-level analysis of the post-IR murine myocardial infarct patches. Changes in function of the remodeling heart were examined in tandem. IR compromised cardiac function and induced LV hypertrophy. During recovery, the IR-induced increase in LV mass was partly offset. IR-induced wall thinning was noted in the anterior aspect of LV and at the diametrically opposite end. Infarct size was observed to be largest on post-IR days 3 and 7. With time (day 28), however, the infarct size was significantly reduced. IR-induced absolute signal-intensity enhancement was highest on post-IR days 3 and 7. As a function of post-IR time, signal-intensity enhancement was attenuated. The threshold of hyperenhanced tissue resulted in delineation of contours that identified necrotic (bona fide infarct) and reversibly injured infarct patches. The study of infarct transmurality indicated that whereas the permanently injured tissue volume remained unchanged, part of the reversibly injured infarct patch recovered in 4 weeks after IR. The approach validated in the current study is powerful in noninvasively monitoring remodeling of the post-IR beating murine myocardium.
It is now understood that the mechanisms leading to neuronal cell death after cerebral ischemia are highly complex. A well established fact in this field is that neurons continue to die over days and months after ischemia, and that reperfusion following cerebral ischemia contributes substantially to ischemic injury. It is now well accepted that central to ischemic/reperfusion-induced injury is what occurs to mitochondria hours to days following the ischemic insult. For many years, it has been established that reactive oxygen species (ROS) and reactive nitrogen species (RNS) promote lipid, protein, and DNA oxidation that affects normal cell physiology and eventually leads to neuronal demise. In addition to oxidation of neuronal molecules by ROS and RNS, a novel pathway for molecular modifications has risen from the concept that ROS can activate specific signal transduction pathways that, depending on the insult degree, can lead to either normal plasticity or pathology. Two examples of these pathways could explain why lethal ischemic insults lead to the translocation of protein kinase Cdelta (deltaPKC), which plays a role in apoptosis after cerebral ischemia, or why sublethal ischemic insults, such as in ischemic preconditioning, lead to the translocation of epsilonPKC, which plays a pivotal role in neuroprotection. A better understanding of the mechanisms by which ROS and/or RNS modulate key protein kinases that are involved in signaling pathways that lead to cell death and survival after cerebral ischemia will help devise novel therapeutic strategies.
Peroxisome Proliferator-Activated Receptor gamma (PPARgamma) ligands have the potential for use as anti-inflammatory agents in chronic airway diseases. We hypothesized that cigarette smoke (CS)-mediated pro-inflammatory cytokine release would be downregulated in the monocyte-macrophage cell line (MonoMac6) by synthetic and natural PPARgamma ligands. Surprisingly, treatment of MonoMac6 cells with the natural PPARgamma ligand 15-deoxy-Delta12,14-prostaglandin J2 led to increased cytokine (IL-8) release in response to either TNF-alpha or CS extract (CSE). However, exposure to rosiglitazone, a synthetic agonist, led to decreased TNF-alpha, but not CSE, mediated cytokine release. Cytokine release correlated with nuclear PPARgamma localization; CSE reduced the amount of activated PPARgamma located in the nucleus and formed aldehyde adducts as PPARgamma protein carbonyls. Furthermore, it was shown that PPARgamma interacts with the RelA/p65 subunit of NF-kappaB under TNF-alpha exposure conditions, but this interaction was disrupted by CS exposure, suggesting that CS blocks this important anti-inflammatory pathway involving PPARgamma. Thus, these new data show that activation of PPARgamma with natural or synthetic ligands have differential inhibitory effects on CS-mediated pro-inflammatory mediator release. These data have implications in designing therapies for treatment of COPD and pulmonary fibrosis.
The mechanism of heme oxygenase-1 (ho-1) gene activation by 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) was examined. 15d-PGJ(2) stimulated expression of HO-1 mRNA and protein and of a mouse ho-1 gene promoter/luciferase fusion construct (HO15luc) in a dose-dependent manner in mouse hepatoma (Hepa) cells. HO15luc expression was not effected by troglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand, but induction by 15d-PGJ(2) was abrogated by the antioxidant N-acetylcysteine. The primary 15d-PGJ(2) responsive sequences were localized to a 5' distal enhancer (E1) and identified as the stress-response element, previously shown to mediate ho-1 activation by several agents, including heme and heavy metals. Treatment of Hepa cells with 15d-PGJ(2) stimulated stress-response element-binding activity as judged by electrophoretic mobility shift assays. Antibody "supershift" experiments identified NF-E2 related factor 2 (Nrf2), but not Fos, Jun, or activating transcription factor/cyclic AMP response element binding protein transcription factors, within the 15d-PGJ(2)-induced complexes. Similarly, a dominant-negative mutant of Nrf2, but not of c-Jun or c-Fos, abrogated 15d-PGJ(2)-stimulated E1 transcription activity. Finally, prior induction of HO-1 in RAW264.7 mouse macrophages by 15d-PGJ(2) attenuated cell death caused by diesel exhaust particle extracts. These results demonstrate that induction of mouse HO-1 expression by 15d-PGJ(2) is independent of PPAR-gamma but dependent on oxidative stress, is regulated by the oxidative stress-activated transcription factor Nrf2, and provides cytoprotective activity.
Here we attempted to test a novel hypothesis that hypoxia may induce Ca(2+) release through reactive oxygen species (ROS)-mediated dissociation of FK506-binding protein 12.6 (FKBP12.6) from ryanodine receptors (RyRs) on the sarcoplasmic reticulum (SR) in pulmonary artery smooth muscle cells (PASMCs). The results reveal that hypoxic exposure significantly decreased the amount of FKBP12.6 on the SR of PAs and increased FKBP12.6 in the cytosol. The colocalization of FKBP12.6 with RyRs was decreased in intact PASMCs. Pharmacological and genetic inhibition of intracellular ROS generation prevented hypoxia from decreasing FKBP12.6 on the SR and increasing FKBP12.6 in the cytosol. Exogenous ROS (H(2)O(2)) reduced FKBP12.6 on the SR and augmented FKBP12.6 in the cytosol. Oxidized FKBP12.6 was absent on the SR from PAs pretreated with and without hypoxia, but it was present with a higher amount in the cytosol from PAs pretreated with than without hypoxia. Hypoxia and H(2)O(2) diminished the association of FKBP12.6 from type 2 RyRs (RyR2). The activity of RyRs was increased in PAs pretreated with hypoxia or H(2)O(2). FKBP12.6 removal enhanced, whereas RyR2 gene deletion blocked the hypoxic increase in [Ca(2+)](i) in PASMCs. Collectively, we conclude that hypoxia may induce Ca(2+) release by causing ROS-mediated dissociation of FKBP12.6 from RyR2 in PASMCs.
Nitrosative stress, where nitrosylation of tyrosine leading to 3-nitrotyrosine proteins or free 3-nitrotyrosine is the most prominent change, has been proposed as a pathogenic mechanism in Parkinson's disease (PD). Levels of 3-nitrotyrosine proteins in serum and cerebrospinal fluid (CSF) of patients with PD have not been studied. Nitrosative stress-induced protein changes in serum and CSF were analyzed in PD patients (n=54) and controls (n=40). Herein we demonstrate the presence of nitrosative stress in serum and CSF of patients with early PD leading to selective increase of 3-nitrotyrosine proteins other than nitroalbumin, without free 3-nitrotyrosine (Hoehn-Yahr stage 1, p<0.05; stage 2, p<0.01). Among 3-nitrotyrosine proteins, nitro-α-synuclein (N-αSyn) was detected in serum, not CSF, and the sites of tyrosine nitrosylation were observed to be modified in patients with early PD. Thus intensity of nitrosylation of Tyr125/136 residues is enhanced (stage 1, p<0.05; stage 2, p<0.01), and that of Tyr39 site is reduced (stage 1, p<0.05), and the ratio between both parameters (N-αSyn-Tyr125/136:N-αSyn-Tyr39 ratio) is significantly higher in early-PD patients (p<0.01). These observations lead to the hypothesis that evaluating nitrosative stress through enhanced levels of 3-nitrotyrosine proteins in serum and CSF without changes in nitroalbumin, together with the profile of tyrosine nitrosylation of serum αSyn characterized by dominant nitrosylation of Tyr125/136 could serve for diagnosis of sporadic Parkinson's disease.
MiR126 was found to be frequently lost in many types of cancer, including malignant mesothelioma (MM), which represents one of the most challenging neoplastic diseases. In this study, we investigated the potential tumor suppressor function of MiR126 in MM cells. The effect of MiR126 was examined in response to oxidative stress, aberrant mitochondrial function induced by inhibition of complex I, mitochondrial DNA (mtDNA) depletion, and hypoxia.
MiR126 was up-regulated by oxidative stress in nonmalignant mesothelial (Met5A) and MM (H28) cell lines. In Met5A cells, rotenone inhibited MiR126 expression, but mtDNA depletion and hypoxia up-regulated MiR126. However, these various stimuli suppressed the levels of MiR126 in H28 cells. MiR126 affected mitochondrial energy metabolism, reduced mitochondrial respiration, and promoted glycolysis in H28 cells. This metabolic shift, associated with insulin receptor substrate-1 (IRS1)-modulated ATP-citrate lyase deregulation, resulted in higher ATP and citrate production. These changes were linked to the down-regulation of IRS1 by ectopic MiR126, reducing Akt signaling and inhibiting cytosolic sequestration of Forkhead box O1 (FoxO1), which promoted the expression of genes involved in gluconeogenesis and oxidative stress defense. These metabolic changes induced hypoxia-inducible factor-1α (HIF1α) stabilization. Consequently, MiR126 suppressed the malignancy of MM cells in vitro, a notion corroborated by the failure of H28(MiR126) cells to form tumors in nude mice.
Innovation and conclusion:
MiR126 affects mitochondrial energy metabolism, resulting in MM tumor suppression. Since MM is a fatal neoplastic disease with a few therapeutic options, this finding is of potential translational importance.
Brain function depends exquisitely on oxygen for energy metabolism. Measurements of brain tissue oxygen tension, by a variety of quantitative and qualitative techniques, going back for >50 years, have led to a number of significant conclusions. These conclusions have important consequences for understanding brain physiology as it is now being explored by techniques such as blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI) and near-infrared spectroscopy (NIRS). It has been known for some time that most of the measured oxygen tensions are less than venous pO2 and are distributed in a spatially and temporally heterogeneous manner on a microregional scale. Although certain large-scale methods can provide reproducible average brain pO2 measurements, no useful concept of a characteristic oxygen tension or meaningful average value for brain tissue oxygen can be known on a microregional level. Only an oxygen field exists with large local gradients due to local tissue respiration, and the most useful way to express this is with a pO2 distribution curve or histogram. The neurons of the brain cortex normally exist in a low-oxygen environment and on activation are oxygenated by increases in local capillary blood flow that lead to increases in hemoglobin saturation and tissue oxygen.
The present study examined whether Aβ(1-42) can induce endogenous expression of interleukin-13 (IL-13) or (IL-4) within activated microglia in the rat hippocampus in vivo. We further investigated whether these cytokines mediate ROS/RNS generation through activation of NADPH oxidase and/or inducible nitric oxide synthase (iNOS), and thus contribute to the degeneration of hippocampal neurons in vivo.
Here, we show that IL-13 and IL-4, endogenously expressed in Aβ(1-42)-activated microglia in hippocampus in vivo, contribute to degeneration of hippocampal neurons in vivo. Neutralization of IL-13 and IL-4 protected hippocampal neurons in vivo against neurotoxicity by inhibiting activation of microglial NADPH oxidase and iNOS, resulting in attenuation of ROS generation and oxidative damage of protein, lipid and DNA.
To our knowledge, this is the first study to demonstrate the possible involvement of endogenously expressed IL-13 and/or IL-4 in activated microglia after Aβ(1-42) injection in the degeneration of hippocampal neurons in vivo. The current findings suggest that the deleterious effects of microglia-derived endogenous IL-13 and/or IL-4 are involved in oxidative stress-mediated neurodegenerative diseases, such as AD.
We carefully hypothesize that IL-13 and IL-4, well-known as anti-inflammatory cytokines might serve as neurotoxic mediators by enhancing microglia-derived oxidative stress in Aβ(1-42)-treated hippocampus in vivo.
Epithelial to mesenchymal transition (EMT) is a fundamental process, paradigmatic of the concept of cell plasticity, that leads epithelial cells to lose their polarization and specialized junctional structures, to undergo cytoskeleton reorganization, and to acquire morphological and functional features of mesenchymal-like cells. Although EMT has been originally described in embryonic development, where cell migration and tissue remodeling have a primary role in regulating morphogenesis in multicellular organisms, recent literature has provided evidence suggesting that the EMT process is a more general biological process that is also involved in several pathophysiological conditions, including cancer progression and organ fibrosis. This review offers first a comprehensive introduction to describe major relevant features of EMT, followed by sections dedicated on those signaling mechanisms that are known to regulate or affect the process, including the recently proposed role for oxidative stress and reactive oxygen species (ROS). Current literature data involving EMT in both physiological conditions (i.e., embryogenesis) and major human diseases are then critically analyzed, with a special final focus on the emerging role of hypoxia as a relevant independent condition able to trigger EMT.
We tested the hypothesis that the constitutive activity of the inducible form of nitric oxide synthase (NOS2) serves to protect cells against numerous endogenous stresses. To accomplish this, we treated HepG2 cell lines that were individually transfected with 13 different promoter/response element (RE) chloramphenicol acetyl transferase (CAT) reporter constructs, with a highly selective NOS2 inhibitor, 1400W [N-(3-(aminomethyl)benzyl) acetamidine)]. HepG2 cells were incubated for 6 h with 0, 1, 10, 50, 100, and 200 microM 1400W, and the activation of the promoter/RE CAT reporter constructs was simultaneously determined. The highest fold inductions occurred at 200 microM 1400W, a concentration that had no effect on overall cell viability, as determined by the MTT assay. Twelve of the 13 promoter/RE CAT reporter constructs were significantly activated by 200 microM 1400W. These results indicate the extensive protective role of constitutive NOS2 against genotoxic, oxidative, and endoplasmic reticulum stresses. The mechanism of this protection may involve the complexing of iron by nitric oxide (NO) to reduce hydroxyl radical formation, NO inhibition of electron transport and the generation of reactive oxygen species within mitochondria, NO inhibition of cyclooxygenase, lipoxygenase, and cytochrome P450 enzyme activity, and the scavenging of superoxide anions by NO to form peroxynitrite.
In response to various stimuli, membrane lipid rafts (LRs) are clustered to aggregate or recruit NADPH oxidase subunits and related proteins in vascular endothelial cells (ECs), forming redox signaling platforms. These LR signaling platforms may play important roles in the normal regulation of endothelial function and in the development of endothelial dysfunction or injury under pathological conditions. This LR-mediated mechanism now takes center stage in cell signaling for the regulation of many cellular activities or cell function such as ECs redox signaling, phagosomal activity of phagocytes, and cell apopotosis of lymphocytes. This brief review summarizes current evidence that relates to the formation of LR redox signaling platforms and their features in ECs, the functional significance of these signaling platforms in mediating death receptor activation-induced endothelial dysfunction, and the mechanisms initiating or promoting the formation of these platforms. It is expected that information provided here will help readers to understand this new signaling mechanism and perhaps extend the LR signaling platform concept to other research areas related to death receptors, redox signaling, endothelial biology, and cell/molecular biology of the cardiovascular system.
In the original research communication, "Mitochondrial Ferritin Attenuates β-Amyloid-Induced Neurotoxicity: Reduction in Oxidative Damage Through the Erk/P38 Mitogen-Activated Protein Kinase Pathways" by Wen-Shuang Wu et al published in Volume 18, Number 2, pages 158-169, the first micrograph of top line was repeated with the 3rd micrograph of bottom line in Fig. 3Ai. We include a replacement figure and regret for the error.
15-Deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) is a cyclopentenone prostaglandin regarded as antiinflammatory mediator, which can act through peroxisome proliferator-activated receptor-gamma (PPARgamma) or through G protein-coupled surface receptors. It has been demonstrated that 15d-PGJ(2) potently increases the generation of interleukin-8 (IL-8) in human microvascular endothelial cells (HMEC-1s); however, the mechanism of this induction is not known. The aim of the study was to find the pathway involved in 15d-PGJ(2)-mediated IL-8 stimulation. Our data confirmed that the effect of 15d-PGJ(2) is independent of PPARgamma. For the first time, we excluded the activation of G proteins and the contribution of G protein-coupled surface receptors in endothelial cells treated with 15d-PGJ(2). Instead, we demonstrated that stimulation of IL-8 involved induction of oxidative stress, activation of p38 kinases, and increase in stability of IL-8 mRNA. Upregulation of IL-8 promoter, although measurable, seemed to play a less-pronounced role. Additionally, our results indicate the involvement of cAMP elevation and may suggest a role for ATF2 transcription factor. Concomitant induction of heme oxygenase-1 in HMEC-1s did not influence the synthesis of IL-8. In summary, we showed that 15d-PGJ(2), acting through oxidative stress, may exert proinflammatory effects. The upregulation of IL-8 is mostly associated with p38-mediated stabilization of mRNA.
The Caenorhabditis elegans Forkhead box O transcription factor (FOXO) homolog DAF-16 functions as a central mediator of multiple biological processes such as longevity, development, fat storage, stress resistance, and reproduction. In C. elegans, similar to other systems, DAF-16 functions as the downstream target of a conserved, well-characterized insulin/insulin-like growth factor (IGF)-1 signaling pathway. This cascade is comprised of an insulin/IGF-1 receptor, which signals through a conserved PI 3-kinase/AKT pathway that ultimately downregulates DAF-16/FOXO activity. Importantly, studies have shown that multiple pathways intersect with the insulin/IGF-1 signaling pathway and impinge on DAF-16 for their regulation. Therefore, in C. elegans, the single FOXO family member, DAF-16, integrates signals from several pathways and then regulates its many downstream target genes.
Many phenolic compounds can act as antioxidants by donating a proton to peroxyl radicals and quenching lipid peroxidation. Phenoxyl radicals produced this way or from metabolism by peroxidases, tyrosinase, or mixed-function oxidases, however, may react with sulfhydryl groups of proteins and other endogenous thiols. In this regard, phenolic compounds may have cytotoxic potential instead of antioxidant effects. We employed the anticancer drug, etoposide (VP-16), as a model phenolic compound to study the sensitivity of ryanodine-sensitive Ca2+ channel (RyR) to VP-16 phenoxyl radicals. The combination of VP-16 and tyrosinase, used to generate the etoposide phenoxyl radical, produced marked Ca2+ release from Ca2+-loaded RyR-rich vesicles prepared from terminal cisternae fraction of sarcoplasmic reticulum (SR). This effect was reversed by the SH-reagent, dithiothreitol (DTT), suggesting that cysteines within the RyR-protein complex were targets for modification by VP-16 phenoxyl radicals. VP-16/tyrosinase-induced release of Ca2+ was attenuated in vesicles prepared from longitudinal SR, which contain relatively little RyR. The effects of the VP-16 phenoxyl radical on Ca2+-ATPase in SR vesicles resembled those observed with caffeine or 4,4'-dithiodipyridine, both of which activate RyR Ca2+ release and lead to activation of Ca2+-ATPase via prolonged Ca2+ cycling. The addition of ruthenium red returned Ca2+-ATPase to its original level. Thus, under these conditions Ca2+-ATPase was not directly affected by VP-16 phenoxyl radical. The hypersensitive SH-groups on RyR are shown to be targets for oxidation of VP-16 phenoxyl radical, and suggest that other phenolic compounds could similarly disrupt Ca2+ homeostasis.
Previously, we showed that angiotensin II stimulation of the NADH/NADPH oxidase is involved in hypertrophy of cultured vascular smooth muscle cells (VSMC). Here, we examine the pathways leading to oxidase activation, and demonstrate that arachidonic acid metabolites mediate hypertrophy by activating the p22phox-based NADH/NADPH oxidase. Angiotensin II stimulates phospholipase A2, releasing arachidonic acid, which stimulates oxidase activity in vitro. When arachidonic acid metabolism is blocked with 5,8,11,14-eicosatetraynoic acid (ETYA) or nordihydroguaiaretic acid (NDGA), oxidase activity decreases by 80 +/- 10%. In VSMC transfected with antisense p22phox to attenuate NADH/NADPH oxidase expression, arachidonic acid is unable to stimulate NADH/NADPH-dependent superoxide production. In these cells, or in cells in which NADH/NADPH oxidase activity is inhibited by diphenylene iodonium, angiotensin II-induced [3H]leucine incorporation is also inhibited. Attenuation of oxidase activation by inhibiting arachidonic acid metabolism with ETYA, NDGA, baicalein, or SKF-525A also inhibits angiotensin II-stimulated protein synthesis (74 +/- 2% and 34 +/- 1%, respectively). Thus, endogenous noncyclooxygenase arachidonic acid metabolites mediate angiotensin II-stimulated protein synthesis in cultured VSMC by activating the NADH/NADPH oxidase, providing mechanistic evidence for redox control of VSMC hypertrophy.
Heme oxygenase (HO)-1, involved in the heme degradation process, is an important antioxidant enzyme. The induction of HO-1 gene expression, in response to diverse oxidative stimuli, represents a critical event in adaptive cellular response. Experimental models of various diseases, including acute inflammation, atherosclerosis, degenerative diseases, and carcinogenesis, have demonstrated that the induction of HO-1 can prevent or mitigate the symptoms associated with these ailments. Recent progress in our understanding of cellular signaling networks as critical modulators of gene transcription sheds light on the molecular basis of HO-1 gene expression. A panel of redox-sensitive transcription factors such as activator protein-1, nuclear factor- kappaB, and nuclear factor E2-related factor-2, and some of the upstream kinases have been identified as regulators of HO-1 gene induction. The scope of this review is limited to focus on molecular mechanisms underlying HO-1 expression and the significance of targeted induction of HO-1 as a strategy to achieve chemoprevention and chemoprotection.
An abundance of scientific literature exists demonstrating that oxidative stress influences the MAPK signaling pathways. This review summarizes these findings for the ERK, JNK, p38, and BMK1 pathways. For each of these different MAPK signaling pathways, the following is reviewed: the proteins involved in the signaling pathways, how oxidative stress can activate cellular signaling via these pathways, the types of oxidative stress that are known to induce activation of the different pathways, and the specific cell types in which oxidants induce MAPK responses. In addition, the functional outcome of oxidative stress-induced activation of these pathways is discussed. The purpose of this review is to provide the reader with an overall understanding and appreciation of oxidative stress-induced MAPK signaling.
The production of reactive oxygen species (ROS) accompanies many signaling events. Antioxidants and ROS scavenging enzymes in general have effects that indicate a critical role for ROS in downstream signaling, but a mechanistic understanding of the contribution of ROS as second messengers is incomplete. Here, the role of reactive oxygen species in cell signaling is discussed, emphasizing the ability of ROS to directly modify signaling proteins through thiol oxidation. Examples are provided of protein thiol modifications that control signal transduction effectors that include protein kinases, phosphatases, and transcription factors. Whereas the effects of cysteine oxidation on these proteins in experimental systems is clear, it has proven more difficult to demonstrate these modifications in response to physiologic stimuli. Improved detection methods for analysis of thiol modification will be essential to define these regulatory mechanisms. Bridging these two areas of research could reveal new regulatory mechanisms in signaling pathways, and identify new therapeutic targets.
Edaravone (MCI-186) is a novel synthetic free radical scavenger intended to have neuroprotective effect against ischemic insult. It is currently used on patients with cerebral infarction. Here, we note beneficial pharmaceutical effects of edaravone in rat experimental traumatic brain injury. Under specific experimental conditions, edaravone minimized traumatic brain injury by functioning as a synthetic antioxidant. Clinical trials testing the efficacy of edaravone are warranted.
Renowned great scientist and redox pioneer, Dr. Britton Chance, closed his 97 years of legendary life on November 16, 2010. He was the Eldridge Reeves Johnson emeritus professor of biophysics, physical chemistry, and radiologic physics at the University of Pennsylvania. He achieved fame as a prominent biophysicist and developer of highly innovative biomedical instrumentation. His scientific career stretched over almost one century and he achieved many scientific and engineering breakthroughs throughout his long prolific career. The advances that he and his colleagues achieved led to great strides in our understanding of biology and disease. He was among the first scientists to recognize the importance of free radicals and reactive oxygen species in mitochondrial metabolism and cells as well as to map pathways of redox biology and signaling. Dr. Chance served as a pioneer and inspiration to generations of researchers in the fields of redox biochemistry, metabolism, and disease. He will be missed by all of us in the research community but will live on through his monumental scientific accomplishments, the novel instrumentation he developed, as well as the many scientists whom he trained and influenced.
Hypoxia-inducible transcription factor (HIF)-prolyl hydroxylases domain (PHD-1-3) are oxygen sensors that regulate the stability of the HIFs in an oxygen-dependent manner. Suppression of PHD enzymes leads to stabilization of HIFs and offers a potential treatment option for many ischemic disorders, such as peripheral artery occlusive disease, myocardial infarction, and stroke. Here, we show that homozygous disruption of PHD-1 (PHD-1(-/-)) could facilitate HIF-1α-mediated cardioprotection in ischemia/reperfused (I/R) myocardium. Wild-type (WT) and PHD-1(-/-) mice were randomized into WT time-matched control (TMC), PHD-1(-/-) TMC (PHD1TMC), WT I/R, and PHD-1(-/-) I/R (PHD1IR). Isolated hearts from each group were subjected to 30 min of global ischemia followed by 2 h of reperfusion. TMC hearts were perfused for 2 h 30 min without ischemia. Decreased infarct size (35%±0.6% vs. 49%±0.4%) and apoptotic cardiomyocytes (106±13 vs. 233±21 counts/100 high-power field) were observed in PHD1IR compared to wild-type ischemia/reperfusion (WTIR). Protein expression of HIF-1α was significantly increased in PHD1IR compared to WTIR. mRNA expression of β-catenin (1.9-fold), endothelial nitric oxide synthase (1.9-fold), p65 (1.9-fold), and Bcl-2 (2.7-fold) were upregulated in the PHD1IR compared with WTIR, which was studied by real-time quantitative polymerase chain reaction. Further, gel-shift analysis showed increased DNA binding activity of HIF-1α and nuclear factor-kappaB in PHD1IR compared to WTIR. In addition, nuclear translocation of β-catenin was increased in PHD1IR compared with WTIR. These findings indicated that silencing of PHD-1 attenuates myocardial I/R injury probably by enhancing HIF-1α/β-catenin/endothelial nitric oxide synthase/nuclear factor-kappaB and Bcl-2 signaling pathway.
The plasminogen activator inhibitor-1 (PAI-1) expression can be enhanced by hypoxia and various stimuli associated with oxidative stress. Among the FOXO transcription factors, FOXO4 appears to be crucial in the response against oxidative stress. Therefore, it was the aim of this study to investigate the role of peroxide-induced oxidative stress and FOXO4 on PAI-1 expression under normoxia and hypoxia. Treatment of cells with hydrogen peroxide increased PAI-1 mRNA, protein, and promoter activity, and knocking down FOXO4 abolished the peroxide-dependent PAI-1 induction. PAI-1 promoter reporter gene assays revealed that the peroxide and FOXO4-dependent induction was mediated through the HIF-1 and CREB-binding HRE within the PAI-1 promoter. Western blot analyses then indicated that peroxide and FOXO4 downregulated HIF-1alpha levels, whereas CREB levels were increased. Chromatin immunoprecipitations showed that FOXO4 did not bind the PAI-1 promoter, whereas CREB binding was enhanced on FOXO4 overexpression. In addition, knockdown of CREB abolished the FOXO4-mediated PAI-1 induction. Together, these findings provide the first evidence that oxidative stress and FOXO4 induce PAI-1 expression through an indirect mechanism involving modulation of HIF-1alpha and CREB protein levels and that enhanced CREB binding to the PAI-1 promoter is critical for the PAI-1 induction under oxidative stress.
SirT1 is a class III histone deacetylase that has been implicated in metabolic and reactive oxygen species control. In the vasculature it has been shown to decrease endothelial superoxide production, prevent endothelial dysfunction and atherosclerosis. However, the mechanisms that mediate SirT1 antioxidant functions remain to be characterized. The transcription factor FoxO3a and the transcriptional coactivator peroxisome proliferator activated receptor γ-coactivator 1α (PGC-1α) have been shown to induce the expression of antioxidant genes and to be deacetylated by SirT1.
Here we investigated SirT1 regulation of antioxidant genes and the roles played by FoxO3a and PGC-1α in this regulation.
We found that SirT1 regulates the expression of several antioxidant genes in bovine aortic endothelial cells, including Mn superoxide dismutase (MnSOD), catalase, peroxiredoxins 3 and 5 (Prx3, Prx5), thioredoxin 2 (Trx2), thioredoxin reductase 2 (TR2), and uncoupling protein 2 (UCP-2) and can be localized in the regulatory regions of these genes. We also found that knockdown of either FoxO3a or PGC-1α prevented the induction of antioxidant genes by SirT1 over-expression. Furthermore, SirT1 increased the formation of a FoxO3a/PGC-1α complex as determined by co-immunoprecipitation (IP) assays, concomitantly reducing H2O2-dependent FoxO3a and PGC-1α acetylation. Data showing that FoxO3a knockdown increases PGC-1α acetylation levels and vice versa, suggest that SirT1 activity on FoxO3a and PGC-1α may be dependent of the formation of a FoxO3a/PGC-1α complex.
A unifying mechanism for SirT1 activities is suggested.
We show that SirT1 regulation of antioxidant genes in vascular endothelial cells depends on the formation of a FoxO3a/PGC-1α complex.
Oxidative stress and mitochondrial dysfunction participate together in the development of heart failure (HF). mRNA levels of monoamine oxidase-A (MAO-A), a mitochondrial enzyme that produces hydrogen peroxide (H(2)O(2)), increase in several models of cardiomyopathies. Therefore, we hypothesized that an increase in cardiac MAO-A could cause oxidative stress and mitochondrial damage, leading to cardiac dysfunction. In the present study, we evaluated the consequences of cardiac MAO-A augmentation on chronic oxidative damage, cardiomyocyte survival, and heart function, and identified the intracellular pathways involved.
We generated transgenic (Tg) mice with cardiac-specific MAO-A overexpression. Tg mice displayed cardiac MAO-A activity levels similar to those found in HF and aging. As expected, Tg mice showed a significant decrease in the cardiac amounts of the MAO-A substrates serotonin and norepinephrine. This was associated with enhanced H(2)O(2) generation in situ and mitochondrial DNA oxidation. As a consequence, MAO-A Tg mice demonstrated progressive loss of cardiomyocytes by necrosis and ventricular failure, which were prevented by chronic treatment with the MAO-A inhibitor clorgyline and the antioxidant N-acetyl-cystein. Interestingly, Tg hearts exhibited p53 accumulation and downregulation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial function. This was concomitant with cardiac mitochondrial ultrastructural defects and ATP depletion. In vitro, MAO-A adenovirus transduction of neonatal cardiomyocytes mimicked the results in MAO-A Tg mice, triggering oxidative stress-dependent p53 activation, leading to PGC-1α downregulation, mitochondrial impairment, and cardiomyocyte necrosis.
Innovation and conclusion:
We provide the first evidence that MAO-A upregulation in the heart causes oxidative mitochondrial damage, p53-dependent repression of PGC-1α, cardiomyocyte necrosis, and chronic ventricular dysfunction.
Increased oxidative stress in vascular cells is implicated in the pathogenesis of atherosclerosis. Reactive oxygen species (ROS) induce vascular inflammation via the proinflammatory cytokine/NF-kappaB pathway. Several lines of evidence suggest that peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1alpha) is an important regulator of intracellular ROS levels. However, no studies have examined the effects of PGC-1alpha on this process. We investigated the effects of PGC-1alpha on inflammatory molecule expression and activity of the redox-sensitive transcription factor, NF-kappaB, in vascular cells. PGC-1alpha expressed in human aortic smooth (HASMCs) and endothelial cells (HAECs) is upregulated by AMP-activated protein kinase activators, including metformin, rosiglitazone and alpha-lipoic acid. Tumor necrosis factor-alpha (TNF-alpha), a major proinflammatory factor in the development of vascular inflammation, stimulates intracellular ROS production through an increase in both mitochondrial ROS and NAD(P)H oxidase activity. Adenovirus-mediated overexpression of the PGC-1alpha gene in HASMCs and HAECs leads to a significant reduction in intracellular and mitochondrial ROS production as well as NAD(P)H oxidase activity. Consequently, NF-kappaB activity and MCP-1 and VCAM-1 induced by TNF-alpha are suppressed. Our data support the possibility that agents stimulating PGC-1alpha expression in the vasculature aid in preventing the development of atherosclerosis.
Pulmonary vascular remodeling associated with pulmonary hypertension is characterized by media thickening, disordered proliferation, and in situ thrombosis. The p21-activated kinase-1 (PAK-1) can control growth, migration, and prothrombotic activity, and the hypoxia-inducible transcription factor HIF-1alpha was associated with pulmonary vascular remodeling. Here we studied whether PAK-1 and HIF-1alpha are linked in pulmonary vascular remodeling. PAK-1 was expressed in the media of remodeled pulmonary vessels from patients with pulmonary vasculopathy and was upregulated, together with its upstream regulator Rac1 and HIF-1alpha in lung tissue from lambs with pulmonary vascular remodeling. PAK-1 and Rac1 were activated by thrombin involving calcium, thus resulting in enhanced generation of reactive oxygen species (ROS) in human pulmonary artery smooth muscle cells (PASMCs). Activation of PAK-1 stimulated HIF activity and HIF-1alpha expression involving ROS and NF-kappaB, enhanced the expression of the HIF-1 target gene plasminogen activator inhibitor-1, and stimulated PASMC proliferation. Importantly, HIF-1 itself bound to the Rac1 promoter and enhanced Rac1 and PAK-1 transcription. Thus, PAK-1 and its activator Rac1 are novel HIF-1 targets that may constitute a positive-feedback loop for induction of HIF-1alpha by thrombin and ROS, thus explaining elevated levels of PAK-1, Rac1, and HIF-1alpha in remodeled pulmonary vessels.
The transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1 α (PPARGC1A or PGC-1α) is a powerful controller of cell metabolism and assures the balance between the production and the scavenging of pro-oxidant molecules by coordinating mitochondrial biogenesis and the expression of antioxidants. However, even though a huge amount of data referring to the role of PGC-1α is available, the molecular mechanisms of its regulation at the transcriptional level are not completely understood. In the present report, we aim at characterizing whether the decrease of antioxidant glutathione (GSH) modulates PGC-1α expression and its downstream metabolic pathways.
We found that upon GSH shortage, induced either by its chemical depletion or by metabolic stress (i.e., fasting), p53 binds to the PPARGC1A promoter of both human and mouse genes, and this event is positively related to increased PGC-1α expression. This effect was abrogated by inhibiting nitric oxide (NO) synthase or guanylate cyclase, implicating NO/cGMP signaling in such a process. We show that p53-mediated PGC-1α upregulation is directed to potentiate the antioxidant defense through nuclear factor (erythroid-derived 2)-like2 (NFE2L2)-mediated expression of manganese superoxide dismutase (SOD2) and γ-glutamylcysteine ligase without modulating mitochondrial biogenesis.
Innovation and conclusions:
We outlined a new NO-dependent signaling axis responsible for survival antioxidant response upon mild metabolic stress (fasting) and/or oxidative imbalance (GSH depletion). Such signaling axis could become the cornerstone for new pharmacological or dietary approaches for improving antioxidant response during ageing and human pathologies associated with oxidative stress.
We have investigated the impact of diaspirin cross-linked hemoglobin (DBBF-Hb), a blood substitute, on cell signaling pathways that are modulated in part by biological peroxides (i.e., hydrogen peroxide, lipid peroxide, and peroxynitrite). Bovine aortic endothelial cells (BAECs) subjected to hypoxia expressed hypoxia-inducible factor (HIF-1alpha) in a time course that paralleled the expressions of heme oxygenase (HO-1). Co-incubation of the oxy form (HbFe(2+)) with hypoxic BAECs resulted in an increase in the expression of HIF-1alpha in a manner that corresponded linearly with the decay of HbFe(2+) and accumulation of the ferric form (HbFe(3+)). Inclusion of HbFe(3+) with hypoxic BAECs produced twice as much expression in the HIF-1alpha and HO-1 proteins as opposed to HbFe(2+) alone, or HbFe(2+) plus hypoxia. In addition, higher and more persistent levels of the ferryl form (HbFe(4+)), due to the consumption of endogenous peroxides, were found in the hypoxic media containing hemoglobin. Nitric oxide (NO) released from an NO donor reduced the levels of HIF-1alpha in the hypoxic cells treated with either HbFe(2+) or HbFe(3+), but had little or no effect on the levels of HO-1. DBBF-Hb modulates key cell-signaling pathways by competing with peroxides required for the deactivation of HIF-1alpha, which may modulate important physiological mediators.
Hypoxia-inducible factor (HIF) is a transcriptional activator that promotes death or survival in neurons. The regulators and targets of HIF-1alpha-mediated death remain unclear. We found that prodeath effects of HIF-1 are not attributable to an imbalance in HIF-1alpha and HIF-1beta expression. Rather, the synergistic death caused by oxidative stress and by overexpression of an oxygen-resistant HIF-VP16 in neuroblasts was attributable to transcriptional upregulation of BH3-only prodeath proteins, PUMA or BNIP3. By contrast, overexpression of BNIP3 was not sufficient to potentiate oxidative death. As acidosis is known to activate BNIP3-mediated death, we examined other secondary stresses, such as oxidants or prolyl hydroxylase activity are necessary for exposing the prodeath functions of HIF in neurons. Antioxidants or prolyl hydroxylase inhibition prevented potentiation of death by HIF-1alpha. Together, these studies suggest that antioxidants and PHD inhibitors abrogate the ability of HIF-mediated transactivation of BH3-only proteins to potentiate oxidative death in normoxia. The findings offer strategies for minimizing the prodeath effects of HIF-1 in neurologic conditions associated with hypoxia and oxidative stress, such as stroke and spinal cord injury.
Translocated in liposarcoma (TLS) is a poorly characterized multifunctional protein involved in the genotoxic response. TLS regulates gene expression at several steps, including splicing and mRNA transport, possibly connecting transcriptional and posttranscriptional events.
In this study we aimed to idenfity molecular targets and regulatory partners of TLS.
Results and innovation:
Here we report that TLS transcriptionally regulates the expression of oxidative stress protection genes. This regulation requires interaction with the transcriptional coactivator peroxisome proliferator activated receptor γ-coactivator 1α (PGC-1α), a master regulator of mitochondrial function that coordinately induces the expression of genes involved in detoxification of mitochondrial reactive oxygen species (ROS). Microarray gene expression analysis showed that TLS transcriptional activity is impaired in the absence of PGC-1α, and is thus largely dependent on PGC-1α.
These results suggest the existence of a regulatory circuit linking the control of ROS detoxification to the coordinated cross-talk between oxidative metabolism and the cellular response to genomic DNA damage.
To elucidate the role of reactive oxygen species (ROS) in arthritis and to identify targets of arthritis treatment in conditions with different levels of oxidant stress.
Through establishing an arthritis model by injecting arthritogenic serum into wildtype and NADPH oxidase 2 (NOX2)-deficient mice, we found that the arthritis had a neutrophilic infiltrate and was more severe in Ncf1-/- mice, a mouse strain lacking the expression of the NCF1/p47phox component of NOX2. The levels of IL-1β and IL-6 in inflamed joints were higher in Ncf1-/- than in controls. Antagonists of TNFα and IL-1β were equally effective in suppressing the arthritis in wildtype mice while IL-1β blockade was more effective than TNFα blockade in Ncf1-/- mice. A treatment of caspase inhibitor and the combination treatment of a caspase inhibitor and a cathepsin inhibitor, but not a cathepsin inhibitor alone, suppressed arthritic severity in the wild type mice, while a treatment of cathepsin inhibitor and the combination treatment of a caspase inhibitor and a cathepsin inhibitor, but not a caspase inhibitor alone, were effective in treating Ncf1-/- mice. Consistently, cathepsin B was found to proteolytically process pro-IL-1β to its active form, and this activity was suppressed by ROS.
This novel mechanism of a redox-mediated immune regulation of arthritis through leukocyte-produced ROS is important for devising optimal treatment for patients with different levels of tissue ROS.
Our results suggest that ROS act as negative feedback to constrain IL-1β-mediated inflammation, accounting for the more severe arthritis in the absence of NOX2.
Studies on thioredoxin (Trx) and its related molecules have expanded dramatically recently. Proteins that share the similar active-site sequence, -Cys-Xxx-Yyy-Cys-, are called the Trx family, and the number of Trx family members is increasing. Trx reductase, which reduces oxidized Trx in cooperation with NADPH, has three isoforms, and peroxiredoxin, which is Trx-dependent peroxidase, has six isoforms. In addition to a role as an antioxidant, Trx and its related molecules play crucial roles in the redox regulation of signal transduction. The classical cytosolic Trx1 and truncated Trx80 are released from cells. Plasma/serum levels of Trx1 are good markers for oxidative stress. Exogenous Trx1 shows cytoprotective and antiinflammatory effects and has a good potential for clinical application. This is an update review on Trx and its related molecules.