(HealthDay News) – Increased expression of MuRF-1, a component of the ubiquitin-proteasome system, is associated with chronic heart failure, and exercise training reduces MuRF-1 levels.
To investigate the molecular mechanism of muscle atrophy in chronic heart failure and its interaction with aging, Stephan Gielen, MD, from the Martin Luther University of Halle/Wittenberg in Germany, and colleagues measured the activation of the ubiquitin-proteasome system in 60 patients with chronic heart failure and 60 healthy controls. Participants were categorized based on age (30 aged <55 years and 30 aged >65 years), and were randomly assigned to four weeks of supervised endurance training or to a control group. Real-time polymerase chain reaction assays were used to measure expression of cathepsin-L and the muscle-specific E3 ligases MuRF-1 and MAFbx.
At baseline, the researchers found that MuRF-1 expression was significantly higher in patients than healthy controls. After four weeks of exercise training, for patients in both age groups, MuRF-1 mRNA expression was significantly reduced (patients ≤55 years: −32.8% [P=0.02]; patients ≥65 years: −37% [P<0.05]).
“MuRF-1, a component of the ubiquitin-proteasome system involved in muscle proteolysis, is increased in the skeletal muscle of patients with heart failure,” the authors write. “Exercise training results in reduced MuRF-1 levels, suggesting that it blocks ubiquitin-proteasome system activation and does so in both younger and older chronic heart failure patients.”