Branched-chain ketoacid ingestion: an alternative to efficiently increase skeletal muscle protein synthesis

Source and Composition in Amino Acid of Dietary Proteins in the Primary Prevention and Treatment of CKD

Nutrition is a cornerstone in the management of chronic kidney disease (CKD). To limit urea generation and accumulation, a global reduction in protein intake is routinely proposed. However, recent evidence has accumulated on the benefits of plant-based diets and plant-derived proteins without a clear understanding of underlying mechanisms. Particularly the roles of some amino acids (AAs) appear to be either deleterious or beneficial on the progression of CKD and its complications. This review outlines recent data on the role of a low protein intake, the plant nature of proteins, and some specific AAs actions on kidney function and metabolic disorders. We will focus on renal hemodynamics, intestinal microbiota, and the production of uremic toxins. Overall, these mechanistic effects are still poorly understood but deserve special attention to understand why low-protein diets provide clinical benefits and to find potential new therapeutic targets in CKD.

Lysine inhibits apoptosis in satellite cells to govern skeletal muscle growth via the JAK2-STAT3 pathway

Apoptosis is programmed cell death that can be stimulated by external stress or nutrition restrictions. However, the precise mechanism of apoptosis in skeletal muscle remains unknown. The objective of this study was to investigate whether apoptosis could be regulated by lysine (Lys) supplementation and the potential mechanism. In this study, an isobaric tag for relative and absolute quantification (iTRAQ) proteomics analysis of the longissimus dorsi muscle from piglets showed that the Janus family tyrosine kinase (JAK)-signal transducer and activator of transcription (STAT) pathway was involved in Lys deficiency-induced apoptosis and inhibited skeletal muscle growth. Meanwhile, western blotting results demonstrated that Lys deficiency led to apoptosis in the longissimus dorsi muscle with the JAK2-STAT3 pathway inhibition. Interestingly, apoptosis was suppressed, and the JAK2-STAT3 pathway was reactivated after Lys re-supplementation. In addition, the results showed that Lys deficiency-induced apoptosis in satellite cells (SCs) was mediated by the JAK2-STAT3 pathway inhibition. Moreover, the JAK2-STAT3 pathway was reactivated by Lys re-supplementation and suppressed cell apoptosis, and this effect was inhibited after treatment with Tyrphostin B42 (AG 490). In conclusion, we found that Lys inhibits apoptosis in SCs to govern skeletal muscle growth via the JAK2-STAT3 pathway.