Mechanisms of protein balance in skeletal muscle

Abstract

Increased global demand for adequate protein nutrition against a backdrop of climate change and concern for animal agriculture sustainability necessitates new and more efficient approaches to livestock growth and production. Anabolic growth is achieved when rates of new synthesis exceed turnover, producing a positive net protein balance. Conversely, deterioration or atrophy of lean mass is a consequence of a net negative protein balance. During early life and periods of growth, muscle mass is driven by increases in protein synthesis at the level of mRNA translation. Throughout life, muscle mass is further influenced by degradative processes such as autophagy and the ubiquitin proteasome pathway. Multiple signal transduction networks guide and coordinate these processes alongside quality control mechanisms to maintain protein homeostasis (proteostasis). Genetics, hormones and environmental stimuli each influence proteostasis control, altering capacity and/or efficiency of muscle growth. An overview of recent findings and current methods to assess muscle protein balance and proteostasis is presented. Current efforts to identify novel control points have the potential through selective breeding design or development of hormetic strategies to better promote growth and health span during environmental stress.

α‐Ketoglutarate prevents skeletal muscle protein degradation and muscle atrophy through PHD3/ADRB2 pathway

“…Excessive protein degradation is the main cause for skeletal muscle atrophy, which is harmful to human health and leads to muscle fatigue and reduced life span (28)(29)(30)(31). Abnormal protein degradation and muscle atrophy generally occur with genetic mutation (DMD) (32), hormone exposure (glucocorticoid) (33), or disease (cachexia) (34).…”

Hyperammonemia and proteostasis in cirrhosis

“…Most studies to date have used the principle of overcoming the anabolic resistance, a state where physiological stimuli including nutrients and physical activity do not result in the expected improvement in skeletal muscle mass or anabolism[11]. Since skeletal muscle is the largest protein store in the body a the balance between protein synthesis and proteolysis, components of protein homeostasis (proteostasis) is a major contributor to maintenance of muscle mass[12]. Protein homeostasis is controlled by the coordinated actions of several cellular processes, including protein synthesis and degradation.…”

“…Maintenance of skeletal muscle mass is a dynamic process that involves a balance between protein synthesis and proteolysis or protein breakdown[12]. Besides protein synthesis and proteolysis, other components that contribute to proteostasis include ribosomal mass and function, mitochondrial function to provide ATP, and the post translational modifications that occur in the endoplasmic reticulum that in the skeletal muscle is specialized to form the sarcoplasmic reticulum[12,14]. The process of protein synthesis is an energy intense process that involves a series of coordinated steps that involve assembly of the mRNAs with the ribosomal subunits for translation into proteins [15].…”

Role of nerve–muscle interactions and reactive oxygen species in regulation of muscle proteostasis with ageing

“…These components are responsible for the fate of unfolded, misfolded or oxidised proteins, i.e. whether they will refold into their original conformation or whether they will be removed from the cell (Kaushik & Cuervo, ; Anthony, ; Hohn et al . ).…”