Laboratory of Bioinorganic and Environmental Toxicology - LABITA, Department of Exact and Earth Sciences, Federal University of São Paulo, Rua Prof. Artur Riedel, 275, CEP 09972-270, Diadema, SP, Brazil.
Metallomics. 2020 Nov 1;12(11):1656-1678. doi: 10.1039/d0mt00085j. Epub 2020 Sep 7.
Manganese (Mn) is essential for living organisms, playing an important role in nervous system function. Nevertheless, chronic and/or acute exposure to this metal, especially during early life stages, can lead to neurotoxicity and dementia by unclear mechanisms. Thus, based on previous works of our group with yeast and zebrafish, we hypothesized that the mechanisms mediating manganese-induced neurotoxicity can be associated with the alteration of protein metabolism. These mechanisms may also depend on the chemical speciation of manganese. Therefore, the current study aimed at investigating the mechanisms mediating the toxic effects of manganese in primary cultures of cerebellar granule neurons (CGNs). By exposing cultured CGNs to different chemical species of manganese ([[2-[(dithiocarboxy)amino]ethyl]carbamodithioato]](2-)-kS,kS']manganese, named maneb (MB), and [1,2-ethanediylbis[carbamodithioato]]manganese mixture with [1,2-ethanediylbis[carbamodithioato]]zinc, named mancozeb (MZ), and manganese chloride (MnCl)), and using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, we observed that both MB and MZ induced similar cytotoxicity (LC∼ 7-9 μM), which was higher than that of MnCl (LC∼ 27 μM). Subsequently, we applied systems biology approaches, including metallomics, proteomics, gene expression and bioinformatics, and revealed that independent of chemical speciation, for non-cytotoxic concentrations (0.3-3 μM), Mn-induced neurotoxicity in CGNs is associated with metal dyshomeostasis and impaired protein metabolism. In this way, we verified that MB induced more post-translational alterations than MnCl, which can be a plausible explanation for cytotoxic differences between both chemical species. The metabolism of proteins is one of the most energy consuming cellular processes and its impairment appears to be a key event of some cellular stress processes reported separately in other studies such as cell cycle arrest, energy impairment, cell signaling, excitotoxicity, immune response, potential protein accumulation and apoptosis. Interestingly, we verified that Mn-induced neurotoxicity shares pathways associated with the development of Alzheimer's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, and Parkinson's disease. This has been observed in baker's yeast and zebrafish suggesting that the mode of action of Mn may be evolutionarily conserved.
锰（Mn）是生物体必需的元素，在神经系统功能中发挥着重要作用。然而，慢性和/或急性暴露于这种金属，尤其是在生命早期阶段，可能会导致神经毒性和痴呆，其机制尚不清楚。因此，基于我们小组之前在酵母和斑马鱼上的工作，我们假设介导锰诱导的神经毒性的机制可能与蛋白质代谢的改变有关。这些机制也可能取决于锰的化学形态。因此，本研究旨在研究原代小脑颗粒神经元（CGN）中锰的毒性作用的介导机制。通过将培养的 CGN 暴露于不同化学形态的锰（[[2-[(二硫代羧基)氨基]乙基]氨基甲二硫代酸根]（2-）-kS，kS']锰，命名为代森锰锌（MB），和 [[1,2-乙二基双[氨基甲二硫代酸根]（2-)]锰与 [[1,2-乙二基双[氨基甲二硫代酸根]（2-)]锌的混合物，命名为代森锰锌（MZ）和氯化锰（MnCl）），并使用 MTT（3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴化物）测定法，我们观察到 MB 和 MZ 均诱导相似的细胞毒性（LC∼7-9 μM），高于 MnCl（LC∼27 μM）。随后，我们应用系统生物学方法，包括金属组学、蛋白质组学、基因表达和生物信息学，揭示了无论化学形态如何，对于非细胞毒性浓度（0.3-3 μM），Mn 诱导的 CGN 神经毒性与金属稳态失衡和蛋白质代谢受损有关。通过这种方式，我们验证了 MB 诱导的翻译后修饰比 MnCl 多，这可以解释两种化学物质之间的细胞毒性差异。蛋白质代谢是细胞中最耗能的过程之一，其损伤似乎是细胞应激过程的关键事件，这些过程分别在其他研究中报道，如细胞周期停滞、能量损伤、细胞信号转导、兴奋毒性、免疫反应、潜在蛋白质积累和细胞凋亡。有趣的是，我们验证了 Mn 诱导的神经毒性与阿尔茨海默病、肌萎缩侧索硬化症、亨廷顿病和帕金森病的发病途径有关。这在酿酒酵母和斑马鱼中得到了验证，表明 Mn 的作用模式可能在进化上是保守的。
