mTORC1信号通路在椎间盘退变中的作用及其机制研究

According to statistics，intervertebral disc degeneration(IDD) is believed to be the most common cause of lubar intervertebral disc protrusion.The onset of IDD is closed related to the changes in compenents of intervertebral disc,however the underlying pathogenesis of IDD is still unclear,which leads to lack of effective prevention and therapy.Mammalian target of rapamycin complex 1(mTORC1) serves as a central regulator of cell metabolism,growth,proliferation and survival.Our preliminary study suggested that specific knock-out TSC1 in chondrocyte during the skeletal development,which up-regulates the mTORC1 signalling,could result in the obvious kyphosis、thoracocyllosis and degeneration of intervertabral disc cartilage.These results indicate that mTORC signalling pathway could play an important role in the composing of intervertebral disc.We intend to dually modulate the mTORC1 signalling in chondrocyte-specific knock-out mice(knock out TSC1 or Raptor) before and after the IDD model established、and the various stages of its growing development.Our proposal aims to study the relationship between mTORC1 signalling activity of chondrocyte and IDD,and investigate the mechanis,which will be beneficial for the further IDD treatment targeting for the mTORC1 signalling of chondrocyte.

椎间盘退变(IDD)是腰椎间盘突出症的重要原因。椎间盘软骨退变与IDD发病紧密相关，但引起椎间盘软骨退变与IDD的原因与分子机制有待阐明。雷帕霉素靶蛋白复合物1(mTORC1)是感受营养与应激信号调节细胞生长与代谢的中心调控分子。课题组前期研究发现：小鼠软骨细胞特异敲除mTORC1上游抑制分子TSC1（mTORC1激活）后，出现脊柱后凸，胸廓发育畸形，椎间盘软骨退化，提示mTORC1活化在椎间盘软骨改变中起重要作用。本课题拟构建立可诱导、软骨细胞特异TSC1或Raptor（mTORC1特异组分）敲除小鼠模型，在其生长发育不同阶段以及IDD造模前后的不同时间，分别使其软骨细胞mTORC1激活和失活，观察其椎间盘退变情况，从分子、细胞与整体水平阐明软骨细胞mTORC1在椎间盘软骨改变与IDD发病中的作用并探讨其分子机制，为IDD发病机制与mTORC1功能增加新内容，为IDD防治提供新靶点。

随着对腰椎间盘突出症病理变化的深入研究发现：椎间盘终板软骨的退变与IDD发病紧密相关，椎间盘终板软骨代谢的失平衡是导致椎间盘突出的重要原因，从而推断椎间盘退变(IDD)是腰椎间盘突出症的重要原因。帕霉素靶蛋白复合物1(mTORC1)是感受营养与应激信号调节细胞生长与代谢的中心调控分子，其信号通路在椎间盘代谢过程中起一定的作用。本研究构建可诱导、软骨细胞特异TSC1敲除小鼠模型，将小鼠软骨细胞特异敲除mTORC1上游抑制分子TSC1，过度激活mTORC1。在其生长发育不同阶段以及IDD造模前后的不同时间，通过x线检查评估椎间盘退变状态，组织病理学检查椎间盘退变变化，Western-blot等检测退变后椎间盘软骨中mTORC1信号通路中的蛋白变化情况，从而观察其椎间盘退变情况。结果显示脊柱出现一定程度的后凸畸形，腰椎椎间盘软骨明显出现退变，椎间盘间隙明显下降，说明mTORC1活化促进椎间盘软骨退变从而导致椎间盘退变，mTORC1活化在椎间盘退变过程中起重要作用。本研究从分子、细胞与整体水平阐明了软骨细胞mTORC1的激活，促进了椎间盘软骨的退变并导致IDD发生，抑制mTORC1功能能预防椎间盘退变。