The combination of ursolic acid and leucine potentiates the differentiation of C2C12 murine myoblasts through the mTOR signaling pathway

Abstract

Abstract. Aging causes phenotypic changes in skeletal muscle progenitor cells that lead to the progressive loss of myogenic differentiation and thus a decrease in muscle mass. The naturally occurring triterpene, ursolic acid, has been reported to be an effective agent for the prevention of muscle loss by suppressing degenerative muscular dystrophy. Leucine, a branched-chain amino acid, and its metabolite, β-hydroxy-β-methylbutyric acid, have been reported to enhance protein synthesis in skeletal muscle. Therefore, the aim of the present study was to investigate whether the combination of ursolic acid and leucine promotes greater myogenic differentiation compared to either agent alone in C2C12 murine myoblasts. Morphological changes were observed and creatine kinase (CK) activity analysis was performed to determine the conditions through which the combination of ursolic acid and leucine would exert the most prominent effects on muscle cell differentiation. The effect of the combination of ursolic acid and leucine on the expression of myogenic differentiation marker genes was examined by RT-PCR and western blot analysis. The combination of ursolic acid (0.5 µM) and leucine (10 µM) proved to be the most effective in promoting myogenic differentiation. The combination of ursolic acid and leucine significantly increased CK activity than treatment with either agent alone. The level of myosin heavy chain, a myogenic differentiation marker protein, was also enhanced by the combination of ursolic acid and leucine. The combination of ursolic acid and leucine significantly induced the expression of myogenic differentiation marker genes, such as myogenic differentiation 1 (MyoD) and myogenin, at both the mRNA and protein level. In addition, the number of myotubes and the fusion index were increased. These findings indicate that the combination of ursolic acid and leucine promotes muscle cell differentiation, thus suggesting that this combination of agents may prove to be beneficial in increasing muscle mass.

Serine is required for the maintenance of redox balance and proliferation in the intestine under oxidative stress

“…However, our results do not exclude the possibility that there exist other signaling pathways mediating the effects of serine. Nevertheless, these results indicated that except for supporting cellular proliferation by providing one‐carbon units and other substrates through its catabolism, serine also activated the signaling pathway that promote proliferation, as other amino acids such as arginine and leucine did . Previous studies had reported several amino acid sensors such as arginine sensors (CASTOR and SLC38A9) and leucine sensor (Sestrin 2) for the mTOR pathway.…”

“…Nevertheless, these results indicated that except for supporting cellular proliferation by providing one-carbon units and other substrates through its catabolism, serine also activated the signaling pathway that promote proliferation, as other amino acids such as arginine and leucine did. 32,33 Previous studies had reported several amino acid sensors such as arginine sensors (CASTOR and SLC38A9) 34,35 and leucine sensor (Sestrin 2) 36 for the mTOR pathway. Consequently, future study is needed to explore serine sensors and elucidate the mechanism by which the mTOR pathway detects and transmits the serine signal.…”

Schisandrae fructus enhances myogenic differentiation and inhibits atrophy through protein synthesis in human myotubes

“…25 Several materials, such as leucine and ursolic acid, as well as exercise, have been known to induce skeletal muscle hypertrophy stimulating v-akt murine thymoma viral oncogene homolog (Akt) or mammalian target of rapamycin (mTOR) signaling. [26][27][28][29][30][31][32] Activation of mTOR generates upregulation of phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (p-4E-BP1) or phosphorylated 70 kDa ribosomal protein S6 kinase (p-P70S6K). Those signals induce hypertrophy by enhancing translation of mRNAs.…”

“…According to the previous studies, many kinds of materials, such as ursolic acid and leucine, 26,32,37,51 as well as exercise that have been known to induce skeletal muscle hypertrophy are associated with mTOR and transforming growth factorbeta signaling. 21,26,27 SF also activated signaling pathway of mTOR/p-P70S6K and p-4E-BP1 in early phases of differentiation (Figure 2).…”

Schisandrae fructus enhances myogenic differentiation and inhibits atrophy through protein synthesis in human myotubes

“…25 Several materials, such as leucine and ursolic acid, as well as exercise, have been known to induce skeletal muscle hypertrophy stimulating v-akt murine thymoma viral oncogene homolog (Akt) or mammalian target of rapamycin (mTOR) signaling. [26][27][28][29][30][31][32] Activation of mTOR generates upregulation of phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (p-4E-BP1) or phosphorylated 70 kDa correspondence: cheol Min Kim center for anti-aging Industry, Pusan National University, 70-16, eomgung-ro, sasang-gu, Busan 47046, republic of Korea Tel +82 51 315 7416 Fax +82 51 583 8820 email kimcm@pusan.ac.kr ribosomal protein S6 kinase (p-P70S6K). Those signals induce hypertrophy by enhancing translation of mRNAs.…”