Redox cellular status

The major determinant of myocardial redox status is the glutathione content of the heart (Griffith and Meister, 1979). Therefore, fluctuations in myocardial glutathione status may exert a regulatory role in cellular metabolism in a comparable manner to the phosphorylation and dephosphorylation of proteins and enzymes. 

If cellular redox state, determined by the glutathione status of the heart, plays a role in the modulation of ion transporter activity in cardiac tissue, it is important to identify possible mechanisms by which these effects are mediated. Protein S-,thiolation is a process that was originally used to describe the formation of adducts of proteins with low molecular thiols such as glutathione (Miller etal., 1990). In view of the significant alterations of cardiac glutathione status (GSH and GSSG) and ion-transporter activity during oxidant stress, the process of S-thiolation may be responsible for modifications of protein structure and function. 

The few reports on bioremediation of colored effluents by yeasts usually mention nonenzymatic processes as the major mechanism for azo dye decolorization [5-10]. In a first approximation based on the cellular viability status, these processes can be divided into two different types bioaccumulation and biosorption. Bioaccumulation usually refers to an active uptake mechanism carried out by living microorganisms (actively growing yeasts). The possibility of further dye biotransformation by redox reactions may also occur due to the involvement of... 

For many years, the cytoprotective effects of plant phenolic compounds were attributed to their ability to direct scavenge oxidants and free radicals. However, as discussed in the last section, this concept is oversimplified and misleading. More and more evidence suggess that plant phenolic compounds could interact with cellular components and trigger a series of cellular responses, which are able to modulate the redox status of the cells and protect the cells from potentially toxic electrophiles/oxidants. 

Castagne V., Gautschi M., Lefevre K., Posada A., and Clarke P. G. H. (1999). Relationships between neuronal death and the cellular redox status. Focus on the developing nervous system. Prog. Neurobiol. 59 397-423. 

Glutamate-Mediated Alterations in Cellular Redox Status... 

In neural cells, the redox status is controlled by the thioredoxin (Trx) and glutathione (GSH) systems that scavenge harmful intracellular ROS. Thioredoxins are antioxidants that serve as a general protein disulphide oxidoreductase (Saitoh et al., 1998). They interact with a broad range of proteins by a redox mechanism based on the reversible oxidation of 2 cysteine thiol groups to a disulphide, accompanied by the transfer of 2 electrons and 2 protons. These proteins maintain their reduced state through the thioredoxin system, which consists of NADPH, thioredoxin reductase (TR), and thioredoxin (Trx) (Williams, Jr. et al., 2000 Saitoh et al., 1998). The thioredoxin system is a system inducible by oxidative stress that reduces the disulfide bond in proteins (Fig. 7.4). It is a major cellular redox system that maintains cysteine residues in the reduced state in numerous proteins. 

Cargnoni, A., Ceconi, C., Gaia, G., Agnoletti, L., and Ferrari, R. 2002. Cellular thiols redox status a switch for NF-kB activation during myocardial post-ischemic reperfusion. J. Mol. Cell. Cardiol. 34 997-1005. 

Liu, W., Kato, M., Akhand, A.A., Hayakawa, A., Suzuki, H., MiyataT., Kurokawa, K., Hotta, Y., Ishikawa, N., and Nakashima, I., 2000, 4-hydroxynonenal induces a cellular redox status-related activation of the caspase cascade forapoptotic cell death,./. Cell. Sci. 113 635-461. 

Much remains to be learned about the redox control of the NFKB/lKBa system. This system is regulated in both a positive and negative way, and each step of that regulation may be subjected to control by oxidation and reduction. The effects of cellular reduction appear to differ in the cellular compartment considered, because reduction suppresses NFkB translocation from the cytoplasm, but may enhance NFkB in the nucleus. Because newly synthesized iKBa is expressed in the nucleus and terminates NFkB function, it will be important to know whether the nuclear redox status also controls this novel, negative function of iKBa. The reactive molecules involved in NFkB... 

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