Regulatory mechanisms involved in blunting protein synthesis in working skeletal muscle

Protein synthesis is suppressed in working skeletal muscle. Teleologically, the skeletal muscle halts an ATP-consuming anabolic process such as protein synthesis to spare ATP for contractile activity during an emergency. So far, 2 mechanisms have been proposed for halting protein synthesis in working muscle. One of these mechanisms suggests that AMPK inhibits mTORC1, which is arguably a master regulator of the initiation step in protein translation. Another theory suggests Ca2+-dependent inactivation of eukaryotic elongation factor 2 (eEF2), which regulates the elongation step in protein translation. Previous reports in the literature suggest that factors other than AMPK and/or eEF2 are involved in the suppression of protein synthesis. We have recently shown that REDD1 might also be involved in blunting protein synthesis in working muscle. Understanding these mechanisms might lead to the development of new strategies and treatments, not only for athletes but also for individuals with muscle-wasting conditions such as sarcopenia.