MAPK信号通路在微囊藻毒素致肝细胞毒性中的作用机制研究

Protein phosphatase 2A (PP2A) plays a key role in the toxic mechanisms of microcystin. Previous studies mainly focus on the effects of microcystin on PP2A. However, after PP2A activity alteration, PP2A downstream targets are the real signal transporters and performers (direct or indirect). Protein phosphatase 2A (PP2A) plays a key role in the toxic mechanisms of microcystin. Previous studies mainly focus on the effects of microcystin on PP2A. However, after PP2A activity alteration, PP2A downstream targets are the real signal transporters and performers. As the direct substrates of PP2A, MAPK superfamily attracts our attention. In our previous studies, using human normal liver cell line, we found that microcystin could induce hyperphosphorylation of HSP27 and Tau through activation of JNK/P38; and subsequently alter these proteins ability of binding to and stabilizing cytoskeleton, inducing cytoskeleton destabilization. Therefore, this project is aim to exploring other hepatotoxicity effects induced by microcystin, and comprehensively exploring the mechanisms of MAPK signal pathways in these toxic effects by detecting MAPKs, their response substrates and related proteins’ interaction. The anticipatory results will highlight the role of PP2A substrates in microcystin-induced hepatotoxicity, and will also provide novel molecular targets for controlling microcystin hepatotoxicity in signal pathways, which have important theoretical significance and application prospects.

蛋白磷酸酶PP2A在微囊藻毒素的致毒机制中具有关键性调控作用，以往的研究更多的关注毒素对PP2A本身的影响，而实际上PP2A活性改变之后，受其调控的下游分子才是真正的信息传递者和功能执行者（直接或间接）。MAPK超家族作为PP2A直接调控的下游底物引起了我们的关注。申请者在前期研究中应用人正常肝细胞模型发现，微囊藻毒素通过激活JNK和p38 MAPK引起HSP27、Tau蛋白超磷酸化，从而影响HSP27和Tau结合并稳定细胞骨架的能力，引起微丝和微管稳定性降低。据此，进一步揭示微囊藻毒素引起的其它肝细胞毒性效应；并且从MAPKs、酶蛋白作用底物的响应、蛋白质相互作用等角度全面探究MAPK通路在毒素致肝细胞毒性中的分子机理是本项目的研究内容。本项目不仅能够从PP2A底物角度进一步阐明微囊藻毒素致肝毒性的分子机制，也能够为从信号通路水平控制其肝毒性提供作用靶点，具有重要的理论意义和应用前景。

微囊藻毒素是水华蓝藻的次级代生产物，以往的研究更多的关注蛋白磷酸酶PP2A在微囊藻毒素的致毒机制中的调控作用。本项目的前期研究结果提示，PP2A直接调控的下游底物MAPK超家族可能才是毒素信号传递的真正调控者。本项目的主要研究内容包括全面揭示微囊藻毒素引起的肝细胞毒性效应，并且从MAPKs酶蛋白作用底物的响应、蛋白质相互作用等角度全面探究MAPK通路在毒素致肝细胞毒性中的分子机理。本研究系统的构建了多浓度、多时段的微囊藻毒素的体外急性肝毒性模型。研究结果证实，微囊藻毒素降低肝细胞粘附性，引起细胞周期分子标志物的改变，激活MAPK家族的P38和ERK1/2通路。而ERK1/2 信号通路作为MAPK超家族的重要成员，在微囊藻毒素的致毒机理研究中，能够调节相关分子标志物的磷酸化水平和在细胞内的定位，从而为受损细胞提供保护机制，以对抗微囊藻毒素的毒性损伤作用。本研究为微囊藻毒素的毒性评价提供可参考、无需重复构建的急性肝毒性模型。为微囊藻毒素的毒性评价提供可检测的分子标志物。 完善了微囊藻毒素的致毒机理，为水华的预防医学毒性检测提供前期研究基础和可参考评价体系。