核转录因子κB信号通路在应力调控成肌细胞分化中的作用

背景:NF-κB信号通路在细胞生长分化、炎症反应、肿瘤生长等过程中发挥重要的调节作用,也参与成肌细胞分化的调控。目的:分析NF-κB信号通路在应力介导的C2C12成肌细胞分化中的作用及其作用机制。方法:成功构建大鼠C2C12成肌细胞体外培养-力学刺激模型,采用多通道细胞牵张应力加载系统,以0.5Hz的加载频率和10%的细胞拉伸变形幅度对细胞进行拉伸培养2,6,12,24h。结果与结论:①C2C12成肌细胞在周期性机械拉伸力作用下,NF-κB信号通路被激活。当细胞受到应力刺激6h后,胞核NF-κBp65亚基蛋白表达水平开始增强,24h内NF-κBp65亚基蛋白表达水平达到峰值。加力12,24h组与未加力对照组之间差异有显著性意义(P<0.05)。②IκBα蛋白表达水平在加力6h后表达显著下降,24h内IκBα蛋白表达水平减弱达到最低。加力12,24h组与未加力对照组之间差异有显著性意义(P<0.05)。③周期性张应力促进C2C12成肌细胞分化过程中Myogenin的表达,加入NF-κB信号通路特异性抑制剂吡咯烷二硫氨基甲酸(20μmol/L)后再加力,Myogenin的表达明显降低。以上结果提示:①NF-κB信号通路可能参与应力介导的C2C12成肌细胞分化的调控过程。②当细胞受到应力刺激时,胞质IκBα发生磷酸化并降解。③NF-κB信号通路在应力介导的C2C12成肌细胞分化过程中发挥重要作用,但不是这一调控过程的惟一通路。

Role of nuclear factor kappa B signaling pathway in stretch-induced differentiation of C2C12 myoblasts

BACKGROUND:Nuclear factor kappa B(NF-κB) is a convergence point of several signaling pathway,playing an important role in cell growth and differentiation,inflammatory response,and tumor growth,as well as regulation of myoblasts differentiation.OBJECTIVE:To investigate the effect and action mechanism of NF-κB signaling pathway on stretch-induced differentiation of C2C12 myoblasts.METHODS:In vitro culture-tensile stimulate models of C2C12 myoblasts were established successfully by using a multi-passage load adding system.Cyclic stretch was applied on the myoblasts for 2,6,12 and 24 hours at an optimal magnitude(10%) and frequency(0.5 Hz).RESULTS AND CONCLUSION:①NF-κB signaling pathway was activated when C2C12 myoblasts were induced by cyclic stretch.The expression of p65 subunit of NF-κB was increased after 6 hours of mechanical stretch,reaching a maximum after 24 hours of mechanical stretch,which was significantly different from the control groups(P < 0.05),confirming a correlation between NF-κB activation and stretch-induced muscle differentiation.②To determine whether IκBα degradation occurred in response to mechanical stretch,C2C12 cells were exposed to cyclic stretch for various time points and total protein extracts were analyzed by Western blot analysis.A significant reduction in the levels of IκBα was observed after 6 hours of mechanical stretch,reaching a minimum after 24 hours of mechanical stretch,significantly different from the control groups(P < 0.05).③Treatment of cells with the specific NF-κB inhibitor,pyrrolidine dithiocarbamate,could decrease the expression of myogenin,but not completely abolish the myogenin expression after stretch.These results indicated that:①NF-κB may be involved in stretch-induced C2C12 cell differentiation.②Phosphorylation and subsequent degradation of IκBα occurs on stimulation of the cells.③NF-κB signaling pathway plays an important role during stretch-induced C2C12 cell differentiation,but is not activated exclusively in this process.