Muscle protein degradation pathway

The muscle protein degradation pathway comprises several interconnected systems that are responsible for breaking down intracellular proteins within skeletal muscle. The main pathways are the ubiquitin–proteasome system (UPS), the autophagy–lysosome pathway, the calcium-dependent calpain system, and the caspase system. The UPS, involving E1/E2/E3 enzymes and the 26S proteasome, specifically tags and degrades short-lived and regulatory proteins, and is particularly upregulated during muscle atrophy. The autophagy–lysosome pathway degrades long-lived proteins and whole organelles. Both are activated by signals such as inflammatory cytokines, glucocorticoids, reactive oxygen species, and impaired insulin/IGF-1 signaling[1][2][5][7]. Common regulatory elements include E3 ubiquitin ligases (notably MuRF1 and Atrogin-1), and the activity or overexpression of these can serve as biomarkers and therapeutic targets within these pathways. Targeting the muscle protein degradation pathway as a whole lacks specificity; modern therapies instead focus on individual pathway components, such as the proteasome, specific E3 ligases, or upstream inflammatory signals. Important caveat: Since "muscle protein degradation pathway" is not a single protein or canonical target, any references to drugs or mechanisms pertain to components within these pathways, not the pathway as a whole. Structured drug databases will reference individual enzymes (such as the proteasome, MuRF1, Atrogin-1) rather than the collective "muscle protein degradation pathway" as a target[2][5][7].

Other names

Skeletal muscle proteolysisMuscle atrophy protein degradationMuscle catabolic pathways

Inhibition of proteasome (proteasome inhibitors); Modulation of autophagy; Inhibition of E3 ubiquitin ligases (e.g., MuRF1, Atrogin-1/MAFbx); Anti-inflammatory action (targeting cytokine-mediated activation)