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Muscle Atrophy Research Paper

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Cellular and Molecular Mechanisms of Muscle Atrophy
The Ubiquitin-Proteasome System The ubiquitin-proteasome system is needed to rid muscles of sarcomeric proteins when there are muscle changes. “A decrease in muscle mass is associated with: (1) An increased conjugation of ubiquitin to muscle proteins; (2) an increased proteasomal ATP-dependent activity; (3) increased protein breakdown that can be efficiently blocked by proteasome inhibitors; and (4) upregulation of transcripts encoding ubiquitin, some ubiquitin-conjugating enzymes (E2), a few ubiquitin- protein ligases (E3) and several proteasome subunits” (Lecker et al., 2006, p. 25). Muscle atrophy is best defined as an active process that is controlled by a specific set of signaling pathways …show more content…

It plays a role in both the conditions and responds to numerous stimuli which includes: nutrient deprivation, cytokines, cellular stress, and amino acid starvation (Mizushima et al., 2008). There have been three different cell mechanisms explained in mammals for delivery of autophagic components to lysosomes: microautophagy, macroautophagy, and chaperone-mediated autophagy (CMA). The extent that CMA is involved in homeostasis of muscles is undefined and should be addressed in detail in the future (Bonaldo & Sandri, 2012). Per analysis of multiple organs, it has been seen determined that skeletal muscle has one of the highest rates of vesicle formation of tissues during fasting. “Autophagy is primarily considered to be a non-selective degradation pathway, but the significance of more selective forms of autophagy is becoming increasingly evident” (Bonaldo & Sandri, 2012, p. 29). In mammals, it is seen that an inactivation of the gene parkin or PINK1, leads to abnormal mitochondria and regulates mitophagy. This gene brings parkin to the mitochondria and endorses mitophagy through ubiquitylation of outer mitochondrial membrane proteins, which brings autophagic vesicles to ubiquitylated mitochondrial proteins (Narenda and Youle, 2011). “The main crucial role of the auto-lysosome system in relation to skeletal muscle is confirmed by the fact that alterations to this process contribute to the pathogenesis …show more content…

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