Tabandeh Mohammad Reza, Hosseini Seyed Ahmad, Hosseini Maryam
a Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine , Shahid Chamran University of Ahvaz , Ahvaz , Iran.
b Cellular and Molecular Research Center (CMRC), Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences (AJUMS) , Ahvaz , Iran.
J Recept Signal Transduct Res. 2017 Aug;37(4):370-378. doi: 10.1080/10799893.2017.1286676. Epub 2017 Feb 14.
Ginsenoside Rb1 improves insulin sensitivity and glucose uptake in muscle cells via different signaling pathways; however, it is not clear that it has any effect on leptin signaling in skeletal muscle.
The aim of this study was to investigate the effect of ginsenoside Rb1 on leptin receptors expression and main signaling pathways of leptin (STAT3, PI3 kinase and ERK kinase) in C2C12 skeletal muscle cells.
C2C12 myotubes were incubated with various concentrations of Rb1 (0.1, 1 and 10 μM) for different incubation times (1-12 h). Leptin receptors expression and GLUT-4 translocation were analyzed using realtime PCR and western blot analyses, respectively. PI3 and ERK kinases were blocked using their specific inhibitors (wortmannin and PD98059) in the presence and absence of RB1 to determine the main signaling pathway related to leptin receptor activation in C2C12 cells.
Rb1 could maximally stimulate both leptin receptors (OBRa and OBRb) mRNA and protein expression and phosphorylation of STAT3, PI3K and ERK2 in C2C12 myotubes at 10 μM for 3 h. Rb1 induced GLUT4 translocation was inhibited by the silencing of OBRb mRNA, demonstrated that glucose uptake was mediated via leptin receptor activation. GLUT4 recruitment to the cell surface induced by Rb1 was inhibited by wortmannin, an inhibitor of PI3K in combination with OBRb siRNA, but not by PD98059 an ERK2 kinase-1 inhibitor, indicating that GLUT4 translocation induced by Rb1 was associated with the leptin receptor upregulation and subsequent activation of PI3K.
Our results suggest that Rb1 promote translocation of GLUT4 by upregulation of leptin receptors and activation of PI3K.
人参皂苷Rb1通过不同的信号通路改善肌肉细胞中的胰岛素敏感性和葡萄糖摄取；然而，其对骨骼肌中瘦素信号传导是否有任何影响尚不清楚。
本研究旨在探讨人参皂苷Rb1对C2C12骨骼肌细胞中瘦素受体表达及瘦素的主要信号通路（信号转导和转录激活因子3、磷脂酰肌醇-3激酶和细胞外信号调节激酶）的影响。
将C2C12肌管与不同浓度的Rb1（0.1、1和10 μM）孵育不同时间（1 - 12小时）。分别使用实时聚合酶链反应和蛋白质免疫印迹分析来检测瘦素受体表达和葡萄糖转运蛋白4转位情况。在存在和不存在Rb1的情况下，使用其特异性抑制剂（渥曼青霉素和PD98059）阻断磷脂酰肌醇-3激酶和细胞外信号调节激酶，以确定与C2C12细胞中瘦素受体激活相关的主要信号通路。
在10 μM浓度下孵育3小时，Rb1可最大程度地刺激C2C12肌管中瘦素受体（OBRa和OBRb）的mRNA和蛋白质表达以及信号转导和转录激活因子3、磷脂酰肌醇-3激酶和细胞外信号调节激酶2的磷酸化。OBRb mRNA沉默抑制了Rb1诱导的葡萄糖转运蛋白4转位，表明葡萄糖摄取是通过瘦素受体激活介导的。渥曼青霉素（一种磷脂酰肌醇-3激酶抑制剂）与OBRb小干扰RNA联合使用可抑制Rb1诱导的葡萄糖转运蛋白4募集到细胞表面，但细胞外信号调节激酶2激酶-1抑制剂PD98059则无此作用，这表明Rb1诱导的葡萄糖转运蛋白4转位与瘦素受体上调及随后的磷脂酰肌醇-3激酶激活有关。
我们的结果表明，Rb1通过上调瘦素受体和激活磷脂酰肌醇-3激酶促进葡萄糖转运蛋白4的转位。
