MK5介导的DJ-1蛋白的磷酸化修饰在脑梗死后神经元凋亡中作用

Stroke is a complex genetic disorder caused by multiple genetic and environmental factors. Recent study reported that a novel association between the locus 12q24.12 and all ischemic stroke subtypes but not cerebral hemorrhage. The gene MAP kinase-activated protein kinase 5 (MK5) is located in locus 12q24.12. However, whether MK5 plays a vital role in the progression of ischemic stroke remains unclear.. Our previous data indicated that MK5 have a neuroprotective effects which can protect neurons from OGD induced injury. The kinase activity of MK5 is important for its protective effects on neurons. However, the detailed mechanisms remains unsolved. By using mass spectral analysis and co-IP analysis, we found that MK5 can interact with DJ-1 and enhance the phosphorylated level of DJ-1. It has been reported that DJ-1 can improve the functional outcomes of ischemic stroke. Based on the above data, we made the assumption that the neuronal apoptosis after ischemic stroke may be attributed to reduced phosphorylated level of DJ-1 which is regulated by MK5. Therefore, we chose to focus on this pathway for our study, and we intend to clarify the possible mechanisms by which MK5 regulates the neuronal apoptosis after ischemic stroke. This study may offer a novel target for neuroprotective treatments after ischemic stroke.

脑梗死是由遗传和环境因素共同作用导致的脑血管病，研究表明染色体12q24.12区域编码基因与脑梗死密切相关，而促分裂原活化蛋白激酶活化蛋白激酶5（MAP kinase-activated protein kinase 5, MK5）编码基因位于染色体12q24.12区域。因此，我们提出：MK5在脑梗死发生发展中起什么作用？. 我们预实验发现MK5蛋白具有神经元保护作用，这与它的激酶活性密切相关。但是，具体机制是什么？前期研究发现MK5可以调节DJ-1的磷酸化修饰。既往研究表明DJ-1蛋白具有神经元保护作用。因此，我们提出假设：MK5介导的DJ-1蛋白的磷酸化修饰在脑梗死后神经元凋亡中起重要作用。本项目拟应用多种基因工程小鼠，以脑梗死后神经元凋亡等表型为切入点，从整体、细胞和分子水平阐明MK5蛋白在脑梗死发生发展中的作用及其机制，将为脑梗死后神经元保护治疗提供新靶点。

研究背景：探索MK5在脑梗死后作用及其在脑梗死后神经元凋亡中的作用机制。 .研究内容：①探讨MK5蛋白在脑梗死后表达变化趋势；②应用MK5敲除小鼠评估MK5对脑梗死后梗死体积及神经功能缺损的影响；③应用MK5敲除小鼠探讨梗死后周边脑组织炎症因子TNF-α，细胞凋亡蛋白Bcl-2、Bax、cleaved-caspase3、γH2aX蛋白表达变化；并检测梗死后小鼠脑组织小胶质细胞、星型胶质细胞、神经元的表达量④采用MK5敲除小鼠检测脑梗死后小鼠缺血半暗带组织p53蛋白的表达量。.研究结果：我们研究发现，WT小鼠在脑缺血后第一天MK5蛋白的表达量最高。与WT小鼠相比，MK5KO小鼠的梗死体积明显增大，神经功能受损明显更严重，炎症因子TNF-α，凋亡蛋白Bcl-2、Bax、cleaved-caspase3、γH2aX等蛋白等表达量明显增加，小鼠单位面积内星型胶质细胞和小胶质细胞阳性细胞数量都增加，神经元阳性神经元数量则减少，TUNEL阳性神经元的数量明显增多。进而进行机制探索，与对照小鼠相比，MK5KO的小鼠p53蛋白表达量明显增加，所以p53可能是MK5的关键性下游分子。.研究结论：MK5 在小鼠脑梗死后的发生发展过程中起到神经保护作用，MK5缺失能够加重脑梗死后神经元凋亡。MK5的作用可能通过调节p53蛋白的表达相关。.科学意义：我们的研究结果显示，MK5缺失能够加重脑梗死后神经元凋亡，加重神经功能缺损，其作用机制可能与其调节p53蛋白的表达相关。