Phenotypic regulation of animal skeletal muscle protein metabolism

Abstract

This review highlights the current state of phenotypic mechanisms of regulation of muscle protein metabolism in animals. Since the skeletal muscle represents 40–50% of body mass in mammals it is a critical regulator of overall metabolism. Therefore, an understanding of the processes involved in the postnatal increase in muscle mass, with associated accumulation of protein, is fundamental. Throughout life, a delicate balance exists between protein synthesis and degradation that is essential for growth and normal health of humans and animals. Signaling pathways coordinate muscle protein balance. Anabolic and catabolic stimuli are integrated through the PKB/Akt-mTORC1 signaling to regulate mechanisms that control muscle protein synthesis and breakdown. At an early periods of intensive growth, muscle mass is stimulated by an increase in protein synthesis at the level of mRNA translation. Throughout the life, proteolytic processes including autophagy lysosomal system, ubiquitin proteasome pathway, calcium-dependent calpains and cysteine protease caspase enzyme cascade influence the growth of muscle mass. Several signal transmission networks direct and coordinate these processes along with quality control mechanisms to maintain protein homeostasis (proteostasis). Genetic factors, hormones, amino acids, phytoecdysteroids, and rhodanines affect the protein metabolism via signaling pathways, changing the ability and / or efficiency of muscle growth.

Effects of dietary 20-hydroxyecdysone supplementation on whole-body protein turnover in growing pigs

“…It is believed that the anabolic adaptogenic effect of them, in particular 20-hydroxyecdysone, can be used in the nutrition of athletes [7]. In experiments on pigs, an increase in protein synthesis and deposition, muscle growth with the introduction of 20-hydroxyecdysone in the diet was found [16]. Feeding these and other phytoecdysteroids causes a decrease in obesity in mice [11,16].…”

“…In experiments on pigs, an increase in protein synthesis and deposition, muscle growth with the introduction of 20-hydroxyecdysone in the diet was found [16]. Feeding these and other phytoecdysteroids causes a decrease in obesity in mice [11,16]. However, recent feeding studies have failed to identify the distinct effects of 20-hydroxyecdysone on Akt or mTORC1 signaling in skeletal muscle [12].…”

Effect of amino acid level and ratio on whole-body protein turnover in piglets

“…Characteristically, the level of digestibility of amino acids should correspond to the needs of animals with a minimum protein content in the diet. In this case, the possibility of increasing the efficiency of using cheaper feed in feeding pigs, in particular, cereal grains with a low protein level, is being solved [3].…”

The role and metabolic functions of the branched-chain amino acids: a review

“…According to recent studies, BCAA affect several synthetic and catabolic cell signaling cascades leading to changes in phenotypes in mammals [1,2,3]. In addition, BCAA have unique properties, performing various physiological and metabolic functions.…”