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Reactive oxygen species (ROS) are engaged in several processes essential for normal cell functioning, such as differentiation, anti-microbial defense, stimulus sensing and signaling. Interestingly, recent studies imply that cellular signal transduction and gene regulation are mediated not only directly by ROS but also by the molecules derived from ROS-mediated oxidation. Lipid peroxidation leads to non-enzymatic formation of oxylipins. These molecules were shown to modulate expression of signaling associated genes including genes encoding phosphatases, kinases and transcription factors. Oxidized peptides derived from protein oxidation might be engaged in organelle-specific ROS signaling. In turn, oxidation of particular mRNAs leads to decrease in the level of encoded proteins and thus, contributes to the post-transcriptional regulation of gene expression. Present mini review summarizes latest findings concerning involvement of products of lipid, protein and RNA oxidation in signal transduction and gene regulation.

Reactive oxygen species (ROS) are engaged in several processes essential for normal cell functioning, such as differentiation, anti-microbial defense, stimulus sensing and signaling. Interestingly, recent studies imply that cellular signal transduction and gene regulation are mediated not only directly by ROS but also by the molecules derived from ROS-mediated oxidation. Lipid peroxidation leads to non-enzymatic formation of oxylipins. These molecules were shown to modulate expression of signaling associated genes including genes encoding phosphatases, kinases and transcription factors. Oxidized peptides derived from protein oxidation might be engaged in organelle-specific ROS signaling. In turn, oxidation of particular mRNAs leads to decrease in the level of encoded proteins and thus, contributes to the post-transcriptional regulation of gene expression. Present mini review summarizes latest findings concerning involvement of products of lipid, protein and RNA oxidation in signal transduction and gene regulation. [ABSTRACT FROM AUTHOR]

The strictly regulated removal of oxidized structures is a universal stress response of eukaryotic cells that targets damaged or toxic components for vacuolar or lysosomal degradation. Autophagy stands at the crossroad between cell survival and death. It promotes survival by degrading proteins and organelles damaged during oxidative stress, but it is also activated as a part of death programs, when the damage cannot be overcome. Evidence is accumulating that the cellular sites of ROS production and signaling may be primary targets of autophagy. Therefore, autophagosomal targeting of mitochondria (mitophagy) is of particular importance. Mitophagy is a selective process that can specifically target dysfunctional mitochondria, but also mitophagy may play a role in controlling the number and quality of mitochondria during stress. Here we review the mechanisms of both non-specific autophagy and mitochondrial targeting in plants, drawing analogies and emphasizing differences with yeast and mammalian systems. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is a small, ubiquitous molecule, whose physiological function in plants has recently been widely investigated. It seems that one of its pivotal properties is the antioxidant capacity, enabling plants to alleviate the effects of the oxidized stress. In this work we investigated the role of NO in soybean ( Glycine max L. Cv. Navico) cell suspension treated with cadmium. Sodium nitroprusside (SNP), nitric oxide donor, markedly decreased the negative influence of Cd2+ on cell growth. It was also found to stimulate superoxide dismutase (SOD, EC 1.15.1.1). Using specific fluorochromes — dihydroethidine (DHE) and 2′,7′- dichlorofluorescein (DCFH-DA) it was shown that NO was very effective in reducing the level of superoxide anion (O) and hydrogen peroxide, respectively. Furthermore, as evaluated by means of NO specific fluorochrome 4,5-diaminofluorescein diacetate (DAF-2DA), increased production of NO was found in Cd-treated cells. In cadmium-stressed cells SNP lowered the level of oxidized proteins. Our results suggest that the antioxidant properties of nitric oxide in Cd-treated soybean cells rely mainly on its ability to direct scavenging of ROS and stimulation of the antioxidant system. [ABSTRACT FROM AUTHOR]

We recently reported that the transient expression of polyglutamine tracts of various size in exon 1 of the huntingtin polypeptide (httEx1) generated abnormally high levels of intracellular reactive oxygen species that directly contributed to cell death. Here, we compared the protection generated by heat shock proteins to that provided by the antioxidant agent N-acetyl-l-cysteine. In cells expressing httEx1 with 72 glutamine repeats (httEx1-72Q), the overexpression of Hsp27 or Hsp70 plus Hdj-1(Hsp40) or treatment of the cells with N-acetyl-l-cysteine inhibited not only mitochondrial membrane potential disruption but also the increase in reactive oxygen species, nitric oxide and protein oxidation. However, only heat shock proteins and not N-acetyl-l-cysteine reduced the size of the inclusion bodies formed by httEx1-72Q. In cells expressing httEx1 polypeptide with 103 glutamine repeats (httEx1-103Q), heat shock proteins neither decreased oxidative damage nor reduced the size of the inclusions. In contrast, N-acetyl-l-cysteine still efficiently decreased the oxidative damage induced by httEx1-103Q polypeptide without altering the inclusions. N-Acetyl-l-cysteine was inactive with regard to proteasome inhibition, whereas heat shock proteins partially restored the caspase-like activity of this protease. These observations suggest some relationships between the presence of inclusion bodies and the oxidative damage induced by httEx1-polyQ. [ABSTRACT FROM AUTHOR]

Modification of proteins by reactive oxygen species is implicated in different disorders. The proteasome is a multicatalytic proteinase in charge of intracellular protein turnover and of oxidized proteins degradation. Consequently, proteasome function is very important in controlling the level of altered proteins in eukaryotic cells. Evidence for a decline in proteasome activity during skin photo-aging has been provided in Bulteau et al. in 2002. The ability of a lipid algae extract (Phaeodactylum tricornutum) to stimulate 20S proteasome peptidase activities was described by Nizard et al. in 2001. Furthermore, keratinocytes treated with Phaeodactylum tricornutum extract and then UVA and UVB irradiated, exhibited a sustained level of proteasome activity comparable to the one of nonirradiated cells. The level of modified proteins can be quantified by measurement of protein carbonyl content (Oxyblot technique), which has been shown to increase with aging and other disorders. In this paper, it is described that, in the presence of this lipid algae extract, the level of oxidized proteins is reduced, as assessed by the Oxyblot technique. These results are obtained both with culture of human keratinocytes and stratum corneum skin cells (obtained by stripping) from human volunteers. Altogether, these results argue for the presence of compounds in this algae extract that have a stimulating and/or protective effect on proteasome activity, resulting in a decreased level of protein oxidation. [ABSTRACT FROM AUTHOR]