Oxidative stress, caused by reactive oxygen and nitrogen species (RONS), is widely recognized as important in both in the pathogenesis and subsequent pathophysiological sequelae of many diseases, including diabetes, cancer, and muscular dystrophy. We have developed a technique using novel molecular probes in conjunction with mass spectrometry to identify targets of oxidative stress in vivo. This proteomics-based approach allows a greater examination of the effects of oxidative stress on many proteins, facilitating insights into the mechanisms through which RONS cause functional changes to muscle tissue in Duchenne Muscular Dystrophy (DMD).
A key target of RONS is the thiol moiety of cysteine residues in proteins. This reversible oxidation has been established as a modulator of protein function. A characteristic of DMD is the loss of muscle function. We have identified significantly increased protein thiol oxidation on several proteins in the mdx mouse model of DMD. Of particular interest is the observed oxidation of the large protein titin, the oxidation of which is known to modulate the passive stiffness of muscle. As muscle stiffness affects contractile strength, this has the potential to increase susceptibility to exercise-induced damage. Titin has not been extensively studied as the large size of the protein renders it inappropriate for traditional gel electrophoresis. This finding exemplifies the value of proteomic, in vivo approaches to examining the effects of oxidative stress in disease models.