Chen Xiaoling, Zhang Man, Jia Gang, Zhao Hua, Liu Guangmang, Huang Zhiqing
Key Laboratory for Animal Disease-Resistance Nutrition of Chinese Ministry of Education, Institute of Animal Nutrition, Sichuan Agricultural University, Chengdu, Sichuan 611130, P.R. China.
Biol Chem. 2022 Jul 18;403(10):959-967. doi: 10.1515/hsz-2022-0165. Print 2022 Sep 27.
The aim of this study was to investigate the effect and mechanism of L-theanine (LT) on muscle fiber type transformation in C2C12 myotubes. Our data showed that LT exhibited significantly higher slow oxidative muscle fiber expression and lower glycolytic fibers expression. In addition, LT significantly increased the activities of malate dehydrogenase (MDH) and succinic dehydrogenase (SDH), and decreased lactate dehydrogenase (LDH) activity, the calcineurin (CaN) activity and the protein expressions of nuclear factor of activated T cell 1 (NFATc1), prospero-related homeobox1 (prox1), and calcineurin A (CnA) were significantly increased. However, inhibition of CaN activity by cyclosporine A (CsA) abolished LT-induced increase of slow oxidative muscle fiber expression and decrease of glycolytic fibers expression. Moreover, inhibition of prox1 expression by prox1-siRNA disrupted LT-induced activation of CaN signaling pathway and muscle fiber type transformation. Taken together, these results indicated that LT could promote skeletal muscle fiber type transformation from type II to type I via activation of prox1/CaN signaling pathway.
本研究旨在探讨L-茶氨酸（LT）对C2C12肌管中肌纤维类型转化的影响及其机制。我们的数据表明，LT显著提高了慢氧化型肌纤维的表达，降低了糖酵解型纤维的表达。此外，LT显著提高了苹果酸脱氢酶（MDH）和琥珀酸脱氢酶（SDH）的活性，降低了乳酸脱氢酶（LDH）的活性，钙调神经磷酸酶（CaN）的活性以及活化T细胞核因子1（NFATc1）、prospero相关同源盒蛋白1（prox1）和钙调神经磷酸酶A（CnA）的蛋白表达显著增加。然而，环孢素A（CsA）抑制CaN活性消除了LT诱导的慢氧化型肌纤维表达增加和糖酵解型纤维表达减少。此外，prox1-siRNA抑制prox1表达破坏了LT诱导的CaN信号通路激活和肌纤维类型转化。综上所述，这些结果表明，LT可通过激活prox1/CaN信号通路促进骨骼肌纤维类型从II型向I型转化。
