title: α-Lipoic Acids Promote the Protein Synthesis of C2C12 Myotubes by the TLR2/PI3K Signaling Pathway.
abstract: Skeletal muscle protein turnover is regulated by endocrine hormones, nutrients, and inflammation. α-Lipoic acid (ALA) plays an important role in energy homeostasis. Therefore, the aim of this study was to investigate the effects of ALA on protein synthesis in skeletal muscles and reveal the underlying mechanism. ALA (25 μM) significantly increased the protein synthesis and phosphorylation of Akt, mTOR, and S6 in C2C12 myotubes with attenuated phosphorylation of AMPK, Ikkα/β, and eIF2α. Intraperitoneal injection of 50 mg/kg ALA also produced the same results in mouse gastrocnemius. Both the PI3K (LY294002) and mTOR (rapamycin) inhibitors abolished the effects of ALA on protein synthesis in the C2C12 myotubes. However, AICAR (AMPK agonist) failed to block the activation of mTOR and S6 by ALA. ALA increased TLR2 and MyD88 mRNA expression in the C2C12 myotubes. TLR2 knockdown by siRNA almost eliminated the effects of ALA on protein synthesis and the Akt/mTOR pathway in the C2C12 myotubes. Immunoprecipitation data showed that ALA enhanced the p85 subunit of PI3K binding to MyD88. These findings indicate that ALA induces protein synthesis and the PI3K/Akt signaling pathway by TLR2.
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Yuanyuan
authors: Y
authors: Jing
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Xingcai
authors: X
authors: Cai
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Yaqiong
authors: Y
authors: Xu
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Canjun
authors: C
authors: Zhu
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Lina
authors: L
authors: Wang
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Songbo
authors: S
authors: Wang
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Xiaotong
authors: X
authors: Zhu
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Ping
authors: P
authors: Gao
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Yongliang
authors: Y
authors: Zhang
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Qingyan
authors: Q
authors: Jiang
authors: College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University , Guangzhou 510640, Guangdong, China.
authors: Gang
authors: G
authors: Shu
mesh_terms: D000818:Animals; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D014176:Protein Biosynthesis; D015398:Signal Transduction; D008063:Thioctic Acid / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D008063:Thioctic Acid; D019869:Phosphatidylinositol 3-Kinases
keywords: TLR2; inflammation; lipoic acid; mTOR; protein synthesis