PICK1调节P2Y6受体介导的小胶质细胞吞噬及其在急性神经损伤中的作用

Microglia are the immune cells in the central nervous system (CNS). Its phagocytosis is very important for maintaining the stability of CNS. During acute brain injury, the clearance of necrotic cells and debris through phagocytic microglia is able to prevent a "secondary damage" caused by these substances. It has been shown that P2Y6 receptors facilitate the phagocytosis of microglia. However, the underlying mechanisms are unclear. Our preliminary work first found that PICK1 regulated the membrane expression of P2Y6 receptors in microglia. In this projece, several techniques including biochemistry, cell biology, pharmacology, electrophysiological recording and knockout mice will be combined to study: 1) Modulation of P2Y6 receptors expression by PICK1 P2Y6 receptor and its mechanisms; 2) Functions of PICK1 in the regulation of microglial phagocytosis; 3) Comparison of acute neuronal injury mediated by microglia phagocytosis in wild-type and PICK1 knockout mice, in order to understand the role of PICK1 in neuronal injury. We expect that this study will promote the understanding of microglial phagocytosis and provide a theoretical basis for the treatment of acute neuronal injury in CNS.

小胶质细胞是中枢神经系统的免疫细胞，其吞噬作用对于维持中枢神经系统的稳定非常重要。大脑急性损伤中小胶质细胞能够通过吞噬坏死细胞及碎片，预防这些物质引起的“二次损伤”。P2Y6受体被证实能够易化小胶质细胞吞噬作用，但其调节机制目前不清楚。我们前期工作首次发现PICK1可以调节小胶质细胞P2Y6受体的膜表达。本项目将综合利用生化、细胞生物学、药理学、电生理记录和基因敲除小鼠等技术，开展如下研究：1) PICK1对P2Y6受体表达的调节功能及其机制；2) PICK1参与调控小胶质细胞的吞噬作用；3) 在正常小鼠和PICK1基因敲除小鼠比较小胶质细胞吞噬介导的急性神经元损伤，以了解PICK1在神经元损伤中的作用。预期研究成果将促进理解小胶质细胞的吞噬功能，为中枢神经系统急性神经元损伤疾病的治疗提供理论基础。

中枢神经系统急性损伤中小胶质细胞膜上P2Y6受体表达增加。受损神经元释放UDP作为“eat-me”信号，通过UDP-P2Y6受体信号系统小胶质细胞可锁定受损神经元并发挥吞噬作用。但在此之前P2Y6受体在小胶质细胞膜上表达改变的调控机制并不清楚。本项目利用生物化学、细胞生物学、药理学、电生理记录以及基因敲除小鼠等，阐明了<1> PICK1能调节小胶质细胞膜上P2Y6受体功能性表达；<2>PICK1分子通过调节P2Y6受体间接调控小胶质细胞吞噬功能；<3>侧脑室注射红藻氨酸诱发癫痫，PICK1基因敲除小鼠由于其细胞膜表面P2Y6受体减少，导致小胶质细胞激活减少。此研究将为进一步研究神经系统急性损伤提供新的理论依据。