Ginsenoside Rb1 and Rb2 upregulate Akt/mTOR signaling – mediated muscular hypertrophy and myoblast differentiation

다국어 초록 (Multilingual Abstract)

Background: As a process of aging, skeletal muscle mass and function gradually decrease. It is reportedthat ginsenoside Rb1 and Rb2 play a role as AMP-activated protein kinase activator, resulting in regulatingglucose homeostasis, and Rb1 reduces oxidative stress in aged skeletal muscles throughactivating the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. We examined the effects of Rb1 and Rb2on differentiation of the muscle stem cells and myotube formation.
Methods: C2C12 myoblasts treated with Rb1 and/or Rb2 were differentiated and induced to myotubeformation, followed by immunoblotting for myogenic marker proteins, such as myosin heavy chain,MyoD, and myogenin, or immunostaining for myosin heavy chain or immunoprecipitation analysis forheterodimerization of MyoD/E-proteins.
Results: Rb1 and Rb2 enhanced myoblast differentiation through accelerating MyoD/E-protein heterodimerization and increased myotube hypertrophy, accompanied by activation of Akt/mammalian target of rapamycin signaling. In addition, Rb1 and Rb2 induced the MyoD-mediatedtransdifferentiation of the rhabdomyosarcoma cells into myoblasts. Furthermore, co-treatment withRb1 and Rb2 had synergistically enhanced myoblast differentiation through Akt activation.
Conclusion: Rb1 and Rb2 upregulate myotube growth and myogenic differentiation through activatingAkt/mammalian target of rapamycin signaling and inducing myogenic conversion of fibroblasts. Thus,our first finding indicates that Rb1 and Rb2 have strong potential as a helpful remedy to prevent andtreat muscle atrophy, such as age-related muscular dystrophy.

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