Wang Tong-Yu, Ma Zhuo, Wang Can, Liu Chang, Yan Dong-Ying, Deng Yu, Liu Wei, Xu Zhao-Fa, Xu Bin
Department of Environmental Health, School of Public Health, China Medical University, People's Republic of China.
Department of Environmental Health, School of Public Health, China Medical University, People's Republic of China.
Toxicol Lett. 2018 Mar 15;285:34-42. doi: 10.1016/j.toxlet.2017.12.024. Epub 2017 Dec 28.
Overexposure to Manganese (Mn) has been known to disrupt neurotransmitter release in the brain. However, the underlying mechanisms of Mn exposure on neurotransmitter vesicle release are still unclear. The current study investigated whether Mn-induced alpha-synuclein protein overexpression could disrupt the Rab3 cycle leading to synaptic vesicle fusion dysfunction. After the neurons were exposed to Mn (100 μM) for 0, 6, 12, 24 h, [Ca], alpha-synuclein and Rab3A-GTP protein expression increased gradually. However, the interaction of synaptotagmin/Rab3-GAP and Rab3A-GTP/Rab3-GAP decreased significantly in response to Mn treatment for 12-24 h. Remarkably, the treatment with Mn caused an increase in the interaction of alpha-synuclein/Rab3A-GTP. To further validate that Mn-induced alpha-synuclein disrupted the proteins interactions of Rab3A-GTP/Rab3-GAP, the lentivirus vector of alpha-synuclein/negative shRNA was transfected in primary cultured neurons to knockdown the expression of alpha-synuclein. Our results showed that the interaction of Rab3A-GTP/Rab3-GAP in alpha-synuclein knockdown neurons treated with Mn for 24 h had a significant recovery. These results suggested that Mn-induced alpha-synuclein protein overexpression, which bound to Rab3A-GTP and inhibited the GTP hydrolysis of Rab3 protein, disrupted the Rab3 cycle leading to synaptic vesicle fusion dysfunction.
已知过度暴露于锰（Mn）会扰乱大脑中的神经递质释放。然而，锰暴露对神经递质囊泡释放的潜在机制仍不清楚。当前的研究调查了锰诱导的α-突触核蛋白过表达是否会破坏Rab3循环，导致突触囊泡融合功能障碍。将神经元暴露于锰（100μM）0、6、12、24小时后，[Ca]、α-突触核蛋白和Rab3A-GTP蛋白表达逐渐增加。然而，在锰处理12-24小时后，突触结合蛋白/Rab3-GAP和Rab3A-GTP/Rab3-GAP的相互作用显著降低。值得注意的是，锰处理导致α-突触核蛋白/Rab3A-GTP的相互作用增加。为了进一步验证锰诱导的α-突触核蛋白破坏了Rab3A-GTP/Rab3-GAP的蛋白质相互作用，将α-突触核蛋白/阴性短发夹RNA的慢病毒载体转染到原代培养的神经元中，以敲低α-突触核蛋白的表达。我们的结果表明，在锰处理24小时的α-突触核蛋白敲低神经元中，Rab3A-GTP/Rab3-GAP的相互作用有显著恢复。这些结果表明，锰诱导的α-突触核蛋白过表达与Rab3A-GTP结合并抑制Rab3蛋白的GTP水解，破坏了Rab3循环，导致突触囊泡融合功能障碍。
