https://staff.blog.ui.ac.id/hsuryadi/files/2012/02/ROS_RNS.pdf

Free radicals and antioxidants in normal physiological functions and human disease

At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...

/pdf/free-radicals-in-the-physiological-control-of-cell-function-g3w3iyr0ph.pdf

Free Radicals in the Physiological Control of Cell Function

▪ Abstract The transcription factor NF-κB, more than a decade after its discovery, remains an exciting and active area of study. The involvement of NF-κB in the expression of numerous cytokines and adhesion molecules has supported its role as an evolutionarily conserved coordinating element in the organism's response to situations of infection, stress, and injury. Recently, significant advances have been made in elucidating the details of the pathways through which signals are transmitted to the NF-κB:IκB complex in the cytosol. The field now awaits the discovery and characterization of the kinase responsible for the inducible phosphorylation of IκB proteins. Another exciting development has been the demonstration that in certain situations NF-κB acts as an anti-apoptotic protein; therefore, elucidation of the mechanism by which NF-κB protects against cell death is an important goal. Finally, the generation of knockouts of members of the NF-κB/IκB family has allowed the study of the roles of these protein...

NF-kappa B and Rel proteins: evolutionarily conserved mediators of immune responses

NF-kappa B is a ubiquitous transcription factor. Nevertheless, its properties seem to be most extensively exploited in cells of the immune system. Among these properties are NF-kappa B's rapid posttranslational activation in response to many pathogenic signals, its direct participation in cytoplasmic/nuclear signaling, and its potency to activate transcription of a great variety of genes encoding immunologically relevant proteins. In vertebrates, five distinct DNA binding subunits are currently known which might extensively heterodimerize, thereby forming complexes with distinct transcriptional activity, DNA sequence specificity, and cell type- and cell stage-specific distribution. The activity of DNA binding NF-kappa B dimers is tightly controlled by accessory proteins called I kappa B subunits of which there are also five different species currently known in vertebrates. I kappa B proteins inhibit DNA binding and prevent nuclear uptake of NF-kappa B complexes. An exception is the Bcl-3 protein which in addition can function as a transcription activating subunit in th nucleus. Other I kappa B proteins are rather involved in terminating NF-kappa B's activity in the nucleus. The intracellular events that lead to the inactivation of I kappa B, i.e. the activation of NF-kappa B, are complex. They involve phosphorylation and proteolytic reactions and seem to be controlled by the cells' redox status. Interference with the activation or activity of NF-kappa B may be beneficial in suppressing toxic/septic shock, graft-vs-host reactions, acute inflammatory reactions, acute phase response, and radiation damage. The inhibition of NF-kappa B activation by antioxidants and specific protease inhibitors may provide a pharmacological basis for interfering with these acute processes.

Function and activation of NF-kappa B in the immune system.

ROS Function in Redox Signaling and Oxidative Stress

Hydrogen peroxide and oxygen radicals are agents commonly produced during inflammatory processes. In this study, we show that micromolar concentrations of H2O2 can induce the expression and replication of HIV-1 in a human T cell line. The effect is mediated by the NF-kappa B transcription factor which is potently and rapidly activated by an H2O2 treatment of cells from its inactive cytoplasmic form. N-acetyl-L-cysteine (NAC), a well characterized antioxidant which counteracts the effects of reactive oxygen intermediates (ROI) in living cells, prevented the activation of NF-kappa B by H2O2. NAC and other thiol compounds also blocked the activation of NF-kappa B by cycloheximide, double-stranded RNA, calcium ionophore, TNF-alpha, active phorbol ester, interleukin-1, lipopolysaccharide and lectin. This suggests that diverse agents thought to activate NF-kappa B by distinct intracellular pathways might all act through a common mechanism involving the synthesis of ROI. ROI appear to serve as messengers mediating directly or indirectly the release of the inhibitory subunit I kappa B from NF-kappa B.

Reactive oxygen intermediates as apparently widely used messengers in the activation of the NF-kappa B transcription factor and HIV-1.

Dithiocarbamates and iron chelators were recently considered for the treatment of AIDS and neurodegenerative diseases. In this study, we show that dithiocarbamates and metal chelators can potently block the activation of nuclear factor kappa B (NF-kappa B), a transcription factor involved in human immunodeficiency virus type 1 (HIV-1) expression, signaling, and immediate early gene activation during inflammatory processes. Using cell cultures, the pyrrolidine derivative of dithiocarbamate (PDTC) was investigated in detail. Micromolar amounts of PDTC reversibly suppressed the release of the inhibitory subunit I kappa B from the latent cytoplasmic form of NF-kappa B in cells treated with phorbol ester, interleukin 1, and tumor necrosis factor alpha. Other DNA binding activities and the induction of AP-1 by phorbol ester were not affected. The antioxidant PDTC also blocked the activation of NF-kappa B by bacterial lipopolysaccharide (LPS), suggesting a role of oxygen radicals in the intracellular signaling of LPS. This idea was supported by demonstrating that treatment of pre-B and B cells with LPS induced the production of O2- and H2O2. PDTC prevented specifically the kappa B-dependent transactivation of reporter genes under the control of the HIV-1 long terminal repeat and simian virus 40 enhancer. The results from this study lend further support to the idea that oxygen radicals play an important role in the activation of NF-kappa B and HIV-1.

Dithiocarbamates as potent inhibitors of nuclear factor kappa B activation in intact cells.

NF-kB is a multiprotein complex that can activate a great variety of genes involved in early defence reactions of higher organisms. In nonstimulated cells, NF-kB resides in the cytoplasm in an inac...

Nuclear Factor Kb: An Oxidative Stress-Responsive Transcription Factor of Eukaryotic Cells (A Review)

We show that AP-1 is an antioxidant-responsive transcription factor. DNA binding and transactivation by AP-1 were induced in HeLa cells upon treatment with the antioxidants pyrrolidine dithiocarbamate (PDTC) and N-acetyl-L-cysteine (NAC), and upon transient expression of the antioxidative enzyme thioredoxin. While PDTC and NAC enhanced DNA binding and transactivation of AP-1 in response to phorbol ester, the oxidant H2O2 suppressed phorbol ester activation of the factor. H2O2 on its own was only a weak inducer of AP-1. Activation of AP-1 by PDTC was dependent on protein synthesis and involved transcriptional induction of c-jun and c-fos genes. Transcriptional activation of c-fos by PDTC was conferred by the serum response element, suggesting that serum response factor and associated proteins function as primary antioxidant-responsive transcription factors. In the same cell line, the oxidative stress-responsive transcription factor NF-kappa B behaved in a manner strikingly opposite to AP-1. DNA binding and transactivation by NF-kappa B were strongly activated by H2O2, while the antioxidants alone were ineffective. H2O2 potentiated the activation of NF-kappa B by phorbol ester, while PDTC and NAC suppressed PMA activation of the factor. PDTC did not influence protein kinase C (PKC) activity and PKC activation by PMA, indicating that the antioxidant acted downstream of and independently from PKC.

R Schreck

Papers

Reactive oxygen intermediates as apparently widely used messengers in the activation of the NF-kappa B transcription factor and HIV-1.

Dithiocarbamates as potent inhibitors of nuclear factor kappa B activation in intact cells.

Nuclear Factor Kb: An Oxidative Stress-Responsive Transcription Factor of Eukaryotic Cells (A Review)

H2O2 and antioxidants have opposite effects on activation of NF-kappa B and AP-1 in intact cells: AP-1 as secondary antioxidant-responsive factor.

A role for oxygen radicals as second messengers