Familial ALS-superoxide dismutases associate with mitochondria and shift their redox potentials

Recent studies suggest that the toxicity of familial amyotrophic lateral sclerosis mutant Cu, Zn superoxide dismutase (SOD1) arises from its selective recruitment to mitochondria. Here we demonstrate that each of 12 different familial ALS-mutant SOD1s with widely differing biophysical properties are associated with mitochondria of motoneuronal cells to a much greater extent than wild-type SOD1, and that this effect may depend on the oxidation of Cys residues. We demonstrate further that mutant SOD1 proteins associated with the mitochondria tend to form cross-linked oligomers and that their presence causes a shift in the redox state of these organelles and results in impairment of respiratory complexes. The observation that such a diverse set of mutant SOD1 proteins behave so similarly in mitochondria of motoneuronal cells and so differently from wild-type SOD1 suggests that this behavior may explain the toxicity of ALS-mutant SOD1 proteins, which causes motor neurons to die

Redox bases underlying the anti-tumor activity of garlic-contained organo-sulfur compounds: Implication in chemoprevention and chemotherapy

The beneficial effects of phytochemicals on human health have been extensively addressed. The majority of this outcome derives from their capability to function as antioxidants, thus the consumption of foods rich in these compounds is considered an advisable preventive therapy in slowing oxidative stress-mediated degenerative processes, such as those occurring during aging. Nevertheless, high concentrations of redox-active compounds could switch the antioxidant property to a pro-oxidant action leading to cell cycle arrest and death. This aspect place phytochemicals as promising therapeutics particularly for cancer prevention or treatment. Although their beneficial properties are known from ancient times, only during the recent years the molecular mechanisms underlying the anti-proliferative effects mediated by garlic-derived organo-sulfur compounds (OSC) are going to be clarified, with particular regard to what their pro-apoptotic features concerns. This chapter discusses the main findings that have contributed to the comprehension of OSC-mediated redox-dependent events governing growth arrest and apoptosis. Particularly, we report the mechanisms through which OSC have been suggested to generate reactive oxygen species and to modulate the redox state of specific reactive cysteines. Both processes will be argued as necessary events in inducing either irreversible damage to cellular macromolecules (e.g. DNA and cytoskeleton proteins), or waves of signaling finally resulting in the activation of the apoptotic program. In this perspective, the classes of proteins which have been indicated to represent the targets of OSC-mediated oxidative modifications, and to have a role in cellular redox response will be discussed

Activation of c-Jun-N-terminal kinase is required for apoptosis triggered by glutathione disulfide in neuroblastoma cells

Changes in intracellular redox status are crucial events that trigger downstream proliferation or death responses through activation of specific signaling pathways. Moreover, cell responses to oxidative challenge may depend on the pattern of redox-sensitive molecular factors. The stress-activated protein kinases c-Jun-N-terminal kinase (JNK) and p38 MAP kinase (p38(MAPK)) are implicated in different forms of apoptotic neuronal cell death. Here, we investigated the effects, on neuroblastoma cells, of the prooxidant molecule GSSG, which we previously demonstrated to be an efficient proapoptotic compound able to activate the p38(MAPK) death pathway in promonocytic cells. We found that neuroblastoma cells are not prone to GSSG-induced apoptosis, although the treatment slightly induced growth arrest through the accumulation of p53 and its downstream target gene, p21. However, GSSG treatment became cytotoxic when cells were previously depleted of intracellular GSH content. Under this condition, apoptosis was triggered by an increased production of superoxide that led to a specific activation of the JNK-dependent pathway. The involvement of superoxide and JNK was demonstrated by cell death inhibition in experiments carried out in the presence of Cu,Zn superoxide dismutase or with specific inhibitors of JNK activity. Our data give support to the studies that indicate preferential requirements for the involvement of stress-activated kinases in apoptotic neuronal cells. (c) 2005 Elsevier Inc. All rights reserved

Glutathione influences c-Myc-induced apoptosis in M14 human melanoma cells

The objective of this article is to dissect the mechanisms by which the down-regulation of c-Myc induces programmed cell death in melanoma cells. In stable and doxycycline-inducible M14 melanoma cells, down-regulation of c-Myc induced apoptosis subsequent to a decrease in the intracellular reduced glutathione content and a concomitant accumulation of its oxidized form. This redox alteration was associated with a decrease of the enzyme activities of γ-glutamyl-cysteine synthetase and NADPH-dependent GSSG reductase, as well as a consequent glutathione release in the extracellular medium. Cytochrome c was released into the cytosol at very early stages of apoptosis induction, long before detectable production of reactive oxygen species and activation of caspase-9 and -3. Macroarray analysis revealed that down-regulation of c-Myc produced striking changes in gene expression in the section related to metabolism, where the expression of γ-glutamyl-cysteine synthetase and GSSG reductase was found to be significantly reduced. The addition of N-acetyl-L-cysteine or glutathione ethyl ester inhibited the apoptotic process, thus confirming the key role of glutathione in programmed cell death induced by c-Myc

Regulatory and structural properties differentiating the chromosomal and the bacteriophage-associated Escherichia coli O157:H7 Cu, Zn Superoxide Dismutases

<p>Abstract</p> <p>Background</p> <p>Highly virulent enterohemorrhagic <it>Escherichia coli </it>O157:H7 strains possess three <it>sodC </it>genes encoding for periplasmic Cu, Zn superoxide dismutases: <it>sodC</it>, which is identical to the gene present in non-pathogenic <it>E. coli </it>strains, and <it>sodC</it>-F1 and <it>sodC</it>-F2, two nearly identical genes located within lambdoid prophage sequences. The significance of this apparent <it>sodC </it>redundancy in <it>E. coli </it>O157:H7 has not yet been investigated.</p> <p>Results</p> <p>We report that strains deleted of one or more <it>sodC </it>genes are less resistant than the wild type strain to a challenge with hydrogen peroxide, thus confirming their involvement in the bacterial antioxidant apparatus. To understand if the different <it>sodC </it>genes have truly overlapping functions, we have carried out a comparison of the functional, structural and regulatory properties of the various <it>E. coli </it>O157:H7 SodC enzymes. We have found that the chromosomal and prophagic <it>sodC </it>genes are differentially regulated <it>in vitro</it>. <it>sodC </it>is exclusively expressed in aerobic cultures grown to the stationary phase. In contrast, <it>sodC</it>-F1 and <it>sodC</it>-F2 are expressed also in the logarithmic phase and in anaerobic cultures. Moreover, the abundance of SodC-F1/SodC-F2 increases with respect to that of SodC in bacteria recovered from infected Caco-2 cells, suggesting higher expression/stability of SodC-F1/SodC-F2 in intracellular environments. This observation correlates with the properties of the proteins. In fact, monomeric SodC and dimeric SodC-F1/SodC-F2 are characterized by sharp differences in catalytic activity, metal affinity, protease resistance and stability.</p> <p>Conclusion</p> <p>Our data show that the chromosomal and bacteriophage-associated <it>E. coli </it>O157:H7 <it>sodC </it>genes have different regulatory properties and encode for proteins with distinct structural/functional features, suggesting that they likely play distinctive roles in bacterial protection from reactive oxygen species. In particular, dimeric SodC-F1 and SodC-F2 possess physico-chemical properties which make these enzymes more suitable than SodC to resist the harsh environmental conditions which are encountered by bacteria within the infected host.</p

COFLEX: FLEXIBLE BRACELET ANTI COVID-19 TO PROTECT CONSTRUCTION WORKERS

Abstract. To implement the protocol contrasting the diffusion of Covid-19, the employer is required, to ensure the safety and health of the worker at work, to adopt measures related to the control of body temperature (with respect for privacy), the minimum distance during work and all other activities such as breaks, canteen breaks, access to toilets, in addition to the adoption of specifically developed safety procedures, such as e.g. the use of man-down detection devices. In this context, the project aims to illustrate a system able of providing support in the safeguarding of workers' health on construction sites. This system, based on information received from sensors capable of identifying workers' positions (e.g., if less than 1m away) and their vital parameters (e.g., body temperature, gasped breathing), as well as moving objects inside the construction site area (e.g., to check if a worker is passing under a moving crane), will raise early alerts directly to the workers and/or to the central software, with respect for privacy, to immediately activate all the necessary measures to mitigate the risk. The system, based on the data communicated by the various sensors, will store and process them for the purpose of extracting useful information for risk management. The proposed system configured itself as a new product taking advantage from a high Technology Readiness Level maturated from the Smart Safety Belt already developed by some of the authors