Oxidation of Peroxiredoxins in Response to Hydrogen Peroxide and Contractile Activity in Skeletal Muscle

Abstract

Skeletal muscle responds to exercise and other environmental changes by modifying the expression and activity of genes involved in regulation of muscle structure, mass and energy metabolism. These responses are attenuated during ageing contributing to reduced muscle mass and function. Exercise generates reactive oxygen species, including hydrogen peroxide (H2O2) which is a key signalling molecule involved in cell responses to stress. A possible mechanism by which increased H2O2 leads to modified gene expression is by reaction of H2O2 with peroxiredoxins (PRX) leading to their oxidation and the formation of disulphide bridges resulting in dimerisation. PRX can then transmit oxidising equivalents to other less reactive proteins by disulphide exchange as part of a redox relay culminating in the activation of specific transcription factors and increased transcription of target genes.This study investigated the oxidation of PRX in the response of muscle to contractile activity and how this pathway was disrupted during ageing. Dimerisation (used as a marker of oxidation) of each PRX was analysed using non‐reducing SDS‐PAGE and western blot analysis. In C2C12 cells PRX1, PRX2 and PRX3 were all found to have increased dimerisation in response to acute treatment with low doses (2.5 and 25μM) of H2O2 in a dose‐dependent manner. A higher dose of H2O2 (250μM) caused all PRXs tested to revert to the monomeric form, consistent with the formation of hyper‐oxidised forms of PRX that are unable to form disulphide bridges. This was confirmed using an antibody specific to hyper‐oxidised PRX.PRX oxidation in response to contractile activity was examined in muscle fibres isolated from the flexor digitalis brevis of adult (6–8 months) or old (26 months) C57BL/6J mice with contractions induced by electrical field stimulation. In fibres from adult mice dimerisation of PRX2 was observed to increase significantly following 2 minutes (28% increase, p<0.05) and 15 minutes of contractions (34% increase, p<0.05), indicating significantly increased PRX2 oxidation. PRX3 dimerisation was significantly increased after 15 minutes of contractions (96% increase, p<0.05) whilst dimerisation of PRX1 remained unchanged. In muscle fibres isolated from old mice there were no significant changes in dimerisation of any of the PRX tested following contractile activity.Contractile activity induced rapid oxidation of PRX2 and PRX3 in skeletal muscle and this process was dysregulated in muscle from old mice. Defects in the regulation of PRX can lead to disruption of downstream signalling pathways and may be responsible for the loss of muscle adaptation to exercise. An understanding of how redox signals are transmitted in muscle following exercise and how they are changed in ageing may help indicate approaches designed to maintain muscle strength in older people.Support or Funding InformationSupported by the UK Medical Research Council (MRC).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.