Expression and Regulation of MuRF-1 and Atrogin-1 are Required for Skeletal Muscle Atrophy

Skeletal muscle atrophy is a debilitating consequence of many pathological conditions and diseases. The mechanisms for muscle atrophy could be attributed to an increase in protein degradation and/or a decrease in protein synthesis. The increase in protein degradation may be caused by the activation of the ubiquitin-proteasome proteolysis pathway. Many studies have confirmed the expression levels of two muscle-specific E3 ubiquitin ligases, MuRF-1 and atrogin-1, are increased in each type of skeletal muscle atrophy. However, the specific substrates for the MuRF-1 and atrogin-1 have not been clearly defined in the muscle degradation process. The expression of these two molecules are regulated by the activation of Nuclear Factor kappa B (NF-kB), forkhead type transcription factors (Foxo), and mitochondrial T3 receptor (p43). The expression and regulation of MuRF-1 and atrogin-1 in different diseases and conditions is the focus of this review. The aim of this review is to assist the research and therapy of skeletal muscle atrophy.