Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan.
Calcif Tissue Int. 2019 Jul;105(1):89-96. doi: 10.1007/s00223-019-00537-w. Epub 2019 Feb 26.
Previous studies suggested that advanced glycation end products (AGEs) and insulin-like growth factor-I (IGF-I) are involved in the mechanism of diabetes-induced sarcopenia. In this study, we examined effects of treatments with AGEs and/or IGF-I for 24 h on myogenic differentiation and apoptosis in mouse myoblastic C2C12 cells. Real-time PCR and Western blot were performed to investigate mRNA and protein expressions, and apoptosis was examined by using a DNA fragment detection ELISA kit. AGE3 significantly decreased mRNA and protein expressions of MyoD and Myogenin, whereas IGF-I significantly increased them and attenuated the effects of AGE3. AGEs significantly decreased endogenous IGF-I mRNA expression and suppressed IGF-I-induced Akt activation. High glucose (22 mM) significantly increased mRNA expression of Rage, a receptor for AGEs, while IGF-I significantly decreased it. DNA fragment ELISA showed that AGE2 and AGE3 significantly increased apoptosis of C2C12 cells, whereas IGF-I significantly suppressed the AGE2- and AGE3-induced apoptosis. In contrast, high glucose enhanced AGE3-induced apoptosis. IGF-I significantly attenuated the effects of high glucose plus AGE3 on the mRNA and protein expressions of MyoD and Myogenin as well as the apoptosis. These findings indicate that AGEs inhibit myogenic differentiation and increase apoptosis in C2C12 cells, and that high glucose increases RAGE and enhances the AGE3-induced apoptosis, suggesting that AGEs and high glucose might contribute to the reduction of muscle mass and function. Moreover, IGF-I attenuated the detrimental effects of AGEs and high glucose in myoblastic cells; thus, IGF-I-Akt signal could be a therapeutic target of DM-induced sarcopenia.
先前的研究表明，晚期糖基化终产物（AGEs）和胰岛素样生长因子-I（IGF-I）参与了糖尿病引起的肌肉减少症的发生机制。在这项研究中，我们研究了用 AGEs 和/或 IGF-I 处理 24 小时对小鼠成肌细胞 C2C12 细胞的成肌分化和凋亡的影响。通过实时 PCR 和 Western blot 检测 mRNA 和蛋白表达，并用 DNA 片段检测 ELISA 试剂盒检测凋亡。AGE3 显著降低了 MyoD 和 Myogenin 的 mRNA 和蛋白表达，而 IGF-I 则显著增加了它们，并减弱了 AGE3 的作用。AGEs 显著降低了内源性 IGF-I mRNA 表达，并抑制了 IGF-I 诱导的 Akt 激活。高葡萄糖（22 mM）显著增加了 AGEs 的受体 Rage 的 mRNA 表达，而 IGF-I 则显著降低了它。DNA 片段 ELISA 显示，AGE2 和 AGE3 显著增加了 C2C12 细胞的凋亡，而 IGF-I 则显著抑制了 AGE2 和 AGE3 诱导的凋亡。相反，高葡萄糖增强了 AGE3 诱导的凋亡。IGF-I 显著减弱了高葡萄糖加 AGE3 对 MyoD 和 Myogenin 的 mRNA 和蛋白表达以及凋亡的影响。这些发现表明，AGEs 抑制 C2C12 细胞的成肌分化并增加凋亡，高葡萄糖增加 RAGE 并增强 AGE3 诱导的凋亡，表明 AGEs 和高葡萄糖可能导致肌肉质量和功能的减少。此外，IGF-I 减弱了 AGEs 和高葡萄糖在成肌细胞中的有害作用；因此，IGF-I-Akt 信号可能是糖尿病引起的肌肉减少症的治疗靶点。
