弓形虫效应分子ROP18抑制Wnt/β-catenin通路干扰神经干细胞分化的机制研究

弓形虫是一种重要的生物致畸因子，其所致先天性脑病严重损害婴幼儿健康。神经干细胞（NSC）在神经系统发育和病理机制中起关键作用。课题组前期研究显示，弓形虫分泌排泄物可抑制NSC分化，其中棒状体蛋白18（ROP18）能抑制Wnt/β-catenin信号通路，从而显著降低NSC内β-catenin以及下游参与神经干细胞分化的Ngn1和Nng2表达，提示ROP18可调控Wnt/β-catenin信号途径干扰NSC分化。本研究采用小鼠原代NSC及其细胞系C17.2以及弓形虫ROP18的缺失突变体，以rROP18转染、胞内共定位、siRNA敲低和回补等，观察NSC形态以及分化标志物、ROP18磷酸化并降解β-catenin及与GSK3β的协同作用等，旨在揭示 ROP18对NSC分化与Wnt/β-catenin信号通路的抑制与调控机制。本研究对于揭示弓形虫脑病的发病机制及制定防治策略，具有重要意义。

Toxoplasma gondii (T.gondii) is a major cause of congenital brain disease. Encephalopathy caused by T. gondii significantly threatens the newborn infants. Neural stem cells (NSCs) play a crucial role in the development of central nervous system and neuropathogensis. Our previous studies indicated that Toxoplasmic excreted/secreted proteins inhibited the differetiation of NSCs, among them rhoptry18(ROP 18) greatly interfered with Wnt/β-catenin pathway and downregulated expressions of β-catenin and Ngn1 and Nng2 that are closely associated with subsequent NSC differentiation, indicating an adverse affect of ROP18 on NSC proliferation and differentiation. Using the primary NSCs of mouse/C17.2 cell line, and ROP18 deletion mutant of T.gondii, here we will have a deep insight into the degredation of ROP18-phosphorylated β-catenin, the synergic effect of GSK3β by rROP18 transfection, intracellular co-localization, siRNA knock-down and knock-in. The aim of the present study is to uncover the inhibitory mechanism of the effector molecule of ROP18 derived from T. gondii in NSCs differetiation via Wnt/β-catenin signaling pathway in Toxoplasmic encephalopathy, and to pave the way for implementation of control strategy of congenital toxoplasmosis.