P38 MAPK相关通路在软骨细胞自噬与凋亡发生及转换中的作用

Autophagy has dual function in the regulation of cell fate, while the complex relationship between autophagy and apoptosis has an important role in the degeneration of OA cartilage and therefore is necessary to be demonstrated. Our previous study mainly aimed on the switches from protective autophagy to apoptosis. Recently, we mainly investigated the mechanisms by which OA initiated, and futher proved that P38 in joint cartilage of OA animal was activated. Further bioinformatics analysis revealed that there might be some binding sites of ATF4 at the region of PLSCR1 promoter. And PLSCR1 might be involved in the regulation of autophagy network , while the detailed regulatory relationship was still not known. Therefore, we decided to use the OA animal model and cultured chondrocytes as the object of this study, and detected the alteration of P38, apoptosis and autophagy markers after inflammatory cytokines stimulation. Further experiment would be took place to judge the cell fate determination function of autophagy in chondrocytes, and the status of ROS in regulating P38. After exploring the role of P38 in regulating downstream transcription factor(such as ATF2, ATF4 and so on) and the pattern by which these transcription factors determine target genes expression, we explored the important function of P38 in the induction and switch of autophagy and autophagy, and further combined the results of gene array to determine the switch mechanisms between autophagy and apoptosis. Therefore, all of the above supported a theoretical basis for OA chondrocytes fate reversion and OA targeting therapy .

自噬是调节细胞命运的双向开关，她与凋亡间复杂的作用关系在关节软骨退变中发挥重要功能，而机制不清。申请人前期工作重点围绕自噬和凋亡的发生及转换机制进行研究。近期工作发现骨关节炎（OA）动物的关节软骨中，P38被显著激活。生物信息学分析进一步提示：PLSCR1启动子区存在转录因子ATF4潜在结合位点。并且，PLSCR1可能参与自噬的网络调节，而机制不清。因此，申请人计划以OA动物模型和培养的软骨细胞为研究对象，首先，检测炎症因子作用下，活性氧、P38、凋亡和自噬的变化情况，明确自噬在软骨细胞命运决定中的作用以及确定活性氧对P38的调控地位；之后，通过探索P38对下游ATF2、ATF4等转录因子的调控地位以及相关转录因子对靶蛋白的表达调控方式，明确P38通路调节自噬和凋亡的分子机制；在此基础上，结合芯片结果，揭示软骨细胞自噬和凋亡转化的具体机制，从而为扭转OA软骨细胞命运及OA靶向治疗提供依据。

本项目重点探索活性氧/P38 MAPK相关信号通路在细胞自噬与凋亡发生及转化中的重要作用。项目执行期内，申请人及其团队采用RNA测序等分子生物学手段，探索并发现P38 MAPK具有调节炎症环境下，软骨细胞自噬发生的功能，且ATF4/PLSCR1信号轴是软骨细胞应对炎症环境的重要反馈，也是调节自噬发生的具体方式。与此同时，申请人研究进一步发现PLSCR1还可以与凋亡诱导因子AIF形成复合体，AIF则可以通过影响PLSCR1与自噬起始复合物Atg5-Atg12的相互作用，解除PLSCR1对细胞自噬的抑制功能，从而具有调节自噬发生的能力。这一调节机制同样与活性氧升高密切相关。鉴于AIF兼有诱导细胞凋亡发生的功能，AIF可被视作细胞自噬与凋亡发生的关键节点蛋白，在细胞命运决定过程中发挥关键作用。此外，项目执行期内，申请人与国内重点高校、研究所展开合作，探索并证实新型纳米药物以活性氧依赖的方式，诱导细胞免疫源性死亡，具有激活免疫的功能。项目执行期内，申请人及其团队严格按照项目年度研究计划执行，完成预期论文及人才培养目标。综上所述，申请人及其团队紧密围绕活性氧、P38 MAPK及PLSCR1的表达及活化研究展开，全面阐述P38 MAPK及其相关通路在细胞命运决定中的关键作用，为疾病的治疗奠定基础。