Lysine Interacts with Frizzled7 to Activate β-Catenin in Satellite Cell-Participated Skeletal Muscle Growth

This work provided an interesting finding of lysine (Lys) control on skeletal muscle growth besides protein synthesis. According to the isobaric tag for relative and absolute quantitation and molecular docking analyses, we found both in in vivo skeletal muscle and in vitro muscle satellite cells (MuSCs) that the frizzled7 (FZD7) expression level was positively correlated with Lys levels and this was consistent with the activation of the Wnt/beta-catenin pathway. On the other hand, FZD7 inhibition suppressed the Lysrescued Wnt/beta-catenin pathway, FZD7 knockdown caused cell proliferation, and Wnt/beta-catenin pathway restrictions could not be compensated for by Lys or Wnt3a. Furthermore, the combination between Lys and recombinant pig frizzled7 (rpFZD7) protein was confirmed by isothermal titration calorimetry. This finding displayed concrete evidence that Lys is not only a molecular block of protein synthesis but is also a ligand for FZD7 to activate beta-catenin to stimulate MuSCs in promoting skeletal muscle growth.

Automated summary

This study revealed that lysine not only controls protein synthesis but also plays a role in regulating skeletal muscle growth. The expression of frizzled7 (FZD7) was positively correlated with lysine levels, and this was consistent with the activation of the Wnt/beta-catenin pathway. In addition, it was found that lysine binds to recombinant pig frizzled7 (rpFZD7) protein. This finding provides concrete evidence that lysine acts as a ligand for FZD7 to activate beta-catenin and stimulate muscle satellite cells (MuSCs) in promoting skeletal muscle growth.