自噬在有机磷化合物诱导的迟发性神经病中的作用及其分子机制

Organophosphorus compounds can cause toxic neuropathy known as organophosphate-induced delayed neuropathy (OPIDN) in human being. Although cases of OPIDN have been documented for over a century, the precise mechanism of OPIDN is still unknown. Our preliminary data indicated that tri-ortho-cresyl phosphate (TOCP) resulted in a significant change in autophagy activity and autophagy-related proteins in hen nerve tissues. Inhibition of autophagy appears to well explain the accumulation of neurofilaments, mitochondria and multivesicular vesicles in the swollen axon observed in OPIDN. Based on these findings, we hypothesize that autophagy dysfunction likely play a causal, pathologic role in OPIDN. This project primarily aims to evaluate the changes of autophagic flux in neurons by examining the formation of autophagosomes, the fusion of autophagosomes and lysosome, and the degradation of autophagic substrates in in vivo and in vitro models following TOCP. To further investigate the molecular mechanisms for autophagy dysfunction and axonal degeneration in OPIDN, we will determine whether there exists a deregulation of Beclin-1-dependent machinery. Additionally, we will examine whether the deregulation of autophagy is associated with the activation of kinases and cytoplasmic proteases, such as AKT, CDK5, calpains and caspases. The project is expected to reveal critical insights into molecular mechanisms underlying the initiation and development of OPIDN. Uncovering these mechanisms will expand our understanding of the pathogenesis of OPIDN, and lead to the development of new therapeutic strategies for preventing or curing OPIDN.

有机磷化合物在人类中能诱发一种迟发性神经病（OPIDN），但其发生机制尚未阐明，因此缺乏有效的防治措施。在前期研究中，我们发现三邻甲苯磷酸酯（TOCP）诱导的OPIDN中脊髓运动神经元自噬活性发生变化，能够较好地解释病理上出现的神经丝、线粒体等变性堆积现象，提示自噬可能在OPIDN发生中起关键作用。本课题拟以TOCP诱导的神经元自噬功能改变为切入点，利用电镜、基因转染、免疫共沉淀和Western blot等技术从整体动物和离体细胞两个水平评价OPIDN中自噬流的改变，明确自噬在OPIDN发生进展中的作用。在此基础上，研究Beclin-1介导的自噬调控机制的可能变化，以及胞浆蛋白酶calpain、caspase 和蛋白激酶AKT、CDK5等与Beclin-1调控变化的关系，探讨有机磷毒物干扰自噬引起轴突病变的潜在机制，以期揭示OPIDN发生的分子机理，为有效地防治OPIDN提供科学依据。

有机磷化合物在人类中能诱发一种迟发性神经病（organophosphorus ester-induced delayed neuropathy，OPIDN），但其发生机制尚未阐明。本研究利用电镜、激光共聚焦、Western blot、qRT-PCR等技术手段，系统研究三邻甲苯磷酸酯(tri-ortho-cresyl phosphate，TOCP)诱导的OPIDN动物模型和细胞模型中神经细胞自噬活性的变化，在此基础上探索TOCP引起自噬变化的可能机制，以期揭示OPIDN发生的分子机制。. 主要的研究发现：. [1] TOCP影响了神经细胞的自噬活性；. [2]TOCP染毒引起LC3、p62/SQSTM1等多种自噬相关蛋白表达的升高；. [3]TOCP染毒激活了LC3、p62等多种自噬相关基因的转录；. [4]Beclin-1介导的调控机制不是TOCP染毒后自噬激活的关键原因；. [5]TOCP染毒促进了p62的磷酸化，导致Keap-1-Nrf2 信号通路的激活。. 本研究结果提示自噬激活是TOCP引起神经元损伤、诱导OPIDN发生过程中的一个关键事件。