Interpretive Summary: Cultured equine satellite cells as a model system to assess leucine stimulated protein synthesis in horse muscle
By Anne Zinn
A research team at the University of Minnesota has found that the amino acid leucine activates the mTOR translation initiation pathway and increases transcription of global proteins in cultured equine satellite cells. This is the first study to examine leucine-stimulated translation initiation in cultured equine satellite cells. The full results of this study, conducted at the University of Minnesota's College of Veterinary Medicine, can be found in the February 2018 edition of the Journal of Animal Science.
Leucine has been shown to regulate the key mammalian/mechanistic target of mTOR pathway that integrates and responds to environmental cues to promote cell growth and is a substrate for protein synthesis. Leucine's role in stimulating protein synthesis has been well established in humans, rats, mice, and pigs, but there has been little data related to the activating role of leucine in equine skeletal muscle. Therefore, the objective of this study was to use cultured equine satellite cells to evaluate the effect of leucine as a regulator of protein synthesis in equine skeletal muscle.
Protein synthesis was evaluated by measuring the incorporation of Phenylalamine in equine satellite cell myotube cultures treated with a leucine titration. To evaluate the mTOR signaling pathway, the research team treated the equine satellite cell myotube cultures with leucine (LEU) or a no-leucine control (CON) in the presence or absence of rapamycin (an inhibitor of mTOR). The study revealed that leucine stimulates protein synthesis in equine skeletal muscle through the activation of downstream effectors of mTOR (4E-BP1 and rS6). Activation of the same initiation factors were completely blocked by rapamycin and mTOR activation was inhibited by rapamycin in the presence of leucine.
Use of the cell culture system with primary equine satellite muscle cells provided the research team the opportunity to distinguish the impact of leucine on muscle and protein synthesis, independent of systemic interactions. This study indicates that cell culture system is a valid method in this type of research. The results will continue to inform future research regarding the equine skeletal muscle and its healthy development.
To view the full article "Cultured equine satellite cells as a model system to assess leucine stimulated protein synthesis in horse muscle," visit the Journal of Animal Science.