Protein catabolism pathways in muscle tissue

Protein catabolism pathways in muscle tissue refer to the collective set of enzymatic and regulatory processes responsible for breaking down muscle proteins—primarily actin, myosin, and other contractile fibers—into peptides and amino acids. These pathways are engaged to maintain protein homeostasis, generate energy from amino acids, and provide substrates for gluconeogenesis, especially during periods of fasting, disease, disuse, or metabolic stress. The main catabolic pathways in muscle involve: - The **ubiquitin-proteasome system** (responsible for targeted degradation of most cytosolic proteins) - The **autophagy-lysosome system** (bulk degradation of protein aggregates and damaged organelles) - **Calpain and caspase pathways** (calcium-dependent and apoptotic proteolysis) Triggers for enhanced muscle protein catabolism include glucocorticoid hormones, inflammatory cytokines (e.g., TNF-α, IL-6), oxidative and metabolic stress, disuse/unloading, nutrient deprivation, and certain disease states (such as cancer, diabetes, chronic kidney disease, AIDS, and aging). Muscle protein catabolism is physiologically opposed by anabolic pathways (primarily mTOR signaling, promoted by insulin and amino acids such as leucine). Dysregulation of these pathways contributes to pathological muscle loss (atrophy, cachexia, sarcopenia)[1][3][6][7]. Note: This entity refers to a class of biological pathways, not a discrete molecular target such as a receptor, enzyme, or transporter. Thus, it is not considered a "therapeutic target" in the strict molecular sense, and "is_incorrect" is true according to the conventions provided.

Other names

Muscle protein breakdown pathwaysSkeletal muscle protein degradation pathways

Inhibition of the ubiquitin-proteasome pathway; Modulation of autophagy-lysosome pathway; Regulation of anabolic/catabolic hormone balance