酸性环境下GPR4介导髓核细胞cAMP蓄积调控椎间盘退变的作用及机制研究

It is known that inflammation and acidic environment are key factors for intervertebral disc degeneration (IDD). And G protein-coupled receptor 4 (GPR4) is a H+ cell sensor. Our previous study indicated that GPR4 regulates IDD under the acidic environment of disc via the inflammation mediated by cAMP accumulation in nucleus pulposus cell. However, the specific effect and mechanism of GPR4 are still largely unknown. Based on our previous study and related research, we propose the hypothesis that GPR4 promotes inflammation under the acidic environment of disc via activating cAMP accumulation-mediated MAPK and NF-κB signaling pathways, then plays the regulating role in IDD. Therefore, in this study, we intend to confirm the effect of GPR4 in regulating IDD under acidic conditions, and clarify the mechanism of GPR4 regulating IDD by promoting inflammation via activating cAMP accumulation-mediated MAPK and NF-κB signaling pathways, through the methods of gene transfection, RNA interference and signal pathway inhibitors. Furthermore, we will validate the effect and mechanism of GPR4 through animal experiments. Our study will provide new targets and insights for the biological therapy of IDD.

已知炎症反应和酸性环境是导致椎间盘退变的关键因素，G蛋白偶联受体4（G protein-coupled receptor 4, GPR4）则是一种细胞H+感受器。我们前期研究发现，酸性环境下GPR4通过介导髓核细胞环磷酸腺苷(cAMP)蓄积，启动炎症反应调控椎间盘退变，但GPR4的具体作用及其机制尚未完全阐明。结合前期研究结果和相关文献，我们提出假说：酸性环境下，GPR4通过介导髓核细胞cAMP蓄积激活炎症信号通路MAPK和NF-κB通路，进而启动炎症反应调控椎间盘退变。为证实假说，我们拟采用基因转染、RNA干扰和信号通路抑制剂等方法，在体外酸性环境下验证GPR4调控椎间盘退变的作用，阐明GPR4通过介导髓核细胞cAMP蓄积激活MAPK和NF-κB通路，进而启动炎症反应调控椎间盘退变的作用机制，并在动物体内进一步验证GPR4的作用及其机制。本研究将为椎间盘退变的生物学治疗提供新的靶点和思路。

椎间盘退变性疾病临床极为常见，目前认为炎症反应和酸性环境是导致椎间盘退变的关键因素。我们研究发现，酸性环境下一种酸感受器G蛋白偶联受体4（G protein-coupled receptor 4, GPR4）可通过介导髓核细胞环磷酸腺苷(cAMP)蓄积，启动炎症反应调控椎间盘退变。通过在本项目中，我们已阐明在椎间盘退变酸性环境下，GPR4通过介导髓核细胞cAMP蓄积，启动cAMP/PKA信号通路，进而激活MAPK和NF-κB信号通路，最终发挥调控椎间盘退变的作用。此外，我们通过动物模型在体内水平验证了GPR4调控椎间盘退变的作用。本项目结果阐明酸性环境下GPR4调控椎间盘退变的作用及具体分子调控机制，从而为椎间盘退变生物学治疗的新靶点提供充分的科学依据，为突破酸性环境限制椎间盘退变生物学治疗效果的瓶颈奠定基础。