过度载荷诱导椎间盘细胞凋亡的力学生物信号转导机制

Over-loading plays an important role in intervertebral disc degeneration by inducing disc cell apoptosis, the mechano-biology signal transduction in this process, however, needs further investigation. The current project attempts to elucidate the mechanism how mechanical stimuli transfer to biological response in over-loading induced disc cell apoptosis. Firstly, the expression of integrins, G-proteins, receptor tyrosine kinases, and stretch-activated ion channels, will be detected by molecular biological methods in degenerated disc tissues from rat models of intervertebral disc degeneration induced by unbalanced dynamic and static forces of the lumbar spine. Secondly, by using a novel culture system, the relative importance of integrins, G-proteins, receptor tyrosine kinases and stretch-activated ion channels, as well as their downstream elements in over-loading induced disc cell apoptosis, will be observed in vitro. Finally, the role of integrin RNA interference in suppressing disc cell apoptosis and in retarding the development of intervertebral disc degeneration will also be investigated. The results of this project will help to better understand the pathogenesis of intervertebral disc degeneration and may provide potential therapy for it.

过度载荷通过诱导椎间盘细胞凋亡在椎间盘退变过程中发挥了重要作用，但椎间盘细胞凋亡的力学生物信号转导机制目前并不清楚。本项目首先通过动物模型观察整合素、G蛋白、受体酪氨酸激酶和牵张激活性离子通道等分子结构是否与动静力失衡所致的大鼠腰椎间盘退变以及椎间盘细胞凋亡相关；其次通过体外细胞培养检测整合素、G蛋白、受体酪氨酸激酶和牵张激活性离子通道在过度载荷诱导的椎间盘细胞凋亡过程中的相对重要性及其各自的下游信号分子；最后通过体内、外实验观察整合素RNA干扰对过度载荷诱导的椎间盘细胞凋亡以及动物模型椎间盘退变的影响。通过本项目试图阐明应力诱导椎间盘细胞凋亡的力学生物信号转导机制，并为椎间盘退变的生物学防治开辟新思路与新途径。

本课题研究了细胞表面力学感受元件的表达与细胞凋亡水平、椎间盘退变的相关性。探讨了整合素β1在过度载荷诱导的大鼠纤维环细胞凋亡过程中的作用及机制。并通过慢病毒介导的integrin β1（整合素β1）基因过表达，观察integrin β1对体内外病理性力学刺激诱导的大鼠椎间盘细胞凋亡的影响。.研究发现，整合素β1、DDR2、TRPV4及BK通道等在大鼠的椎间盘组织中均有不同表达，退变的椎间盘组织中整合素β1表达减少、细胞过度凋亡。过度牵张载荷刺激后纤维环细胞凋亡增多，其原因可能是应力刺激使细胞膜表面的整合素（主要是β1）功能障碍，继而引起FAK、Src的活性降低，ERK1/2的磷酸化水平降低，JNK、p38磷酸化水平增高，启动了细胞凋亡进程。慢病毒介导的ITGβ1过表达使周期性牵张载荷诱导的纤维环细胞凋亡率降低。椎间盘内直接注射ITGβ1过表达慢病毒载体抑制动静力失衡诱发的椎间盘细胞凋亡，并缓解椎间盘退变。.本研究系统的探讨了过度载荷诱导椎间盘细胞凋亡的力学信号转导机制，对深入了解椎间盘退变发生的力学及分子机制具有重要意义。同时，本研究为椎间盘退变的基因治疗提供了新的治疗靶点。