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What do we really know about the ubiquitin-proteasome pathway in muscle atrophy?Studies of many different rodent models of muscle wasting have indicated that accelerated proteolysis via the ubiquitin-proteasome pathway is the principal cause of muscle atrophy induced by fasting, cancer cachexia, metabolic acidosis, denervation, disuse, diabetes, sepsis, burns, hyperthyroidism and excess glucocorticoids. However, our understanding about how muscle proteins are degraded, and how the ubiquitin-proteasome pathway is activated in muscle under these conditions, is still very limited. The identities of the important ubiquitin-protein ligases in skeletal muscle, and the ways in which they recognize substrates are still largely unknown. Recent in-vitro studies have suggested that one set of ubquitination enzymes, E2(14K) and E3(alpha), which are responsible for the 'N-end rule' system of ubiquitination, plays an important role in muscle, especially in catabolic states. However, their functional significance in degrading different muscle proteins is still unclear. This review focuses on the many gaps in our understanding of the functioning of the ubiquitin-proteasome pathway in muscle atrophy, and highlights the strengths and limitations of the different experimental approaches used in such studies.
Document ID
20040112313
Document Type
Reprint (Version printed in journal)
Authors
Jagoe, R. T. (Harvard Medical School Boston, Massachusetts 02115, United States)
Goldberg, A. L.
Date Acquired
August 21, 2013
Publication Date
May 1, 2001
Publication Information
Publication: Current opinion in clinical nutrition and metabolic care
Volume: 4
Issue: 3
ISSN: 1363-1950
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Review
Review, Tutorial
Non-NASA Center
NASA Discipline Musculoskeletal