miR-29调控PTEN参与铝致突触可塑性损伤的机制研究

Aluminum is a widely exposed neurotoxicant. Excessive exposure to aluminum induces cognitive impairment. Synaptic plasticity impairment is main toxic mechanism caused by aluminum.The role of miRNAs in diseases of the nervous system is a hotspot in recent years.miR-29 can regulate the protuberant number of neurons and the growth of axon, further miR-29 is associated with synaptic plasticity. Previous study have found that aluminum can cause the change of miR-29 , might affect its target gene PTEN, might affect PI3K/Akt signaling pathways regulated by PTEN negatively, lead to the change of the activity of GSK-3 beta, then influence the expression of AMPA receptors, finally reduce synaptic transmission efficiency. This research will establish aluminum- exposed model and intervention model through in vivo study, Lateral ventricle stereotaxic injection study and in vitro study. Further detect the change of LTP in neuro, observe the chang of miR-29, PTEN and GSK-3beta signaling pathway related moleculars. This research aims to investigate aluminum- induced neurotoxicity from the viewpoint of miRNA, to explore the mechanism of miR-29 on GSK-3β signaling pathway regulated by PTEN in the synaptic plasticity injury induced by aluminum exposure. Furthermore, This research not only provides new informations for investigating the mechanism of aluminum- induced cognitive impaiment, but also try to take these moleculars as biomarkers for aluminum- induced neurotoxicity.

铝作为一种常见的神经毒物，主要表现为学习记忆功能降低，并表现为突触可塑性改变。miR-29能够引起神经元突起数量增加，轴突生长，与突触可塑性有关。前期研究发现铝暴露可致大鼠海马miR-29含量改变，可能会影响其靶基因PTEN的表达，影响对PI3K/Akt信号通路的负性调控，影响GSK-3β的活性，进而影响AMPA受体的表达，最后降低突触传递效能。本研究拟通过体内实验、侧脑室立体定位实验及体外实验建立铝中毒及干预模型，测定神经元LTP变化、miR-29变化、PTEN及GSK-3β信号通路相关分子的变化；旨在探索miR-29调控的PTEN及GSK-3β信号通路在铝致突触可塑性损伤中的作用，从miRNA水平阐明铝的神经毒性，为铝致认知功能损害机理提供新资料，并尝试将上述分子作为铝致神经毒性生物标志物。

铝作为一种常见的神经毒物，主要损伤学习记忆能力，并表现为突触可塑性损伤。miRNAs是近年来神经毒理学的研究热点，并参与了突触可塑性形成与调节过程。miRNA能够作用于特异靶基因，对突触功能与形态能够进行动态修饰及调控，从而影响突触可塑性和记忆形成。研究发现miR-29能够调控细胞增殖，突起数量增加，轴突生长，项目旨在探讨miR-29作为可能作用靶点，参与铝致突触可塑性损伤的可能环节和机制。因脑内miR-29a表达量最高，本项目选择miR-29a作为靶分子研究，动物体内实验发现铝可时间及剂量依赖性地损伤小鼠学习记忆能力并损伤突触可塑性，表现为突触后致密斑厚度变小，突触界面曲率减小，树突棘密度降低；分子生物学实验结果发现铝可降低小鼠海马miR-29a的水平，并提高其靶基因PTEN mRNA及蛋白水平，抑制PI3K/Akt/GSK-3β信号通路， 降低AMPA受体的表达；以上结果提示miR-29a/PTEN信号通路与铝损伤突触可塑性相关联。体外实验通过构建miR-29a慢病毒转染载体对小鼠海马原代神经元进行转染从而提高miR-29a的表达。体外实验结果发现miR-29a可增强小鼠海马原代神经元活力，降低PTEN mRNA及蛋白水平，激活PI3K/Akt/GSK-3β信号通路，促进小鼠海马原代神经元突起生长，促进原代神经元网络构建，改善神经元电活动。本项目研究证实了miR-29作为靶分子参与铝致突触可塑性损伤机制的假说，从miRNA水平阐明铝的神经毒性，为铝致认知功能损害机理提供新资料，并尝试将上述分子作为铝致神经毒性生物标志物。