Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina.
Neurochem Int. 2011 Aug;59(2):297-308. doi: 10.1016/j.neuint.2011.06.001. Epub 2011 Jun 16.
Manganese (Mn) is a trace element known to be essential for maintaining the proper function and regulation of many biochemical and cellular reactions. However, chronic exposure to high levels of Mn in occupational or environmental settings can lead to its accumulation in the brain resulting in a degenerative brain disorder referred to as Manganism. Astrocytes are the main Mn store in the central nervous system and several lines of evidence implicate these cells as major players in the role of Manganism development. In the present study, we employed rat astrocytoma C6 cells as a sensitive experimental model for investigating molecular mechanisms involved in Mn neurotoxicity. Our results show that C6 cells undergo reactive oxygen species-mediated apoptotic cell death involving caspase-8 and mitochondrial-mediated pathways in response to Mn. Exposed cells exhibit typical apoptotic features, such as chromatin condensation, cell shrinkage, membrane blebbing, caspase-3 activation and caspase-specific cleavage of the endogenous substrate poly (ADP-ribose) polymerase. Participation of the caspase-8 dependent pathway was assessed by increased levels of FasL, caspase-8 activation and Bid cleavage. The involvement of the mitochondrial pathway was demonstrated by the disruption of the mitochondrial membrane potential, the opening of the mitochondrial permeability transition pore, cytochrome c release, caspase-9 activation and the increased mitochondrial levels of the pro-apoptotic Bcl-2 family proteins. In addition, our data also shows for the first time that mitochondrial fragmentation plays a relevant role in Mn-induced apoptosis. Taking together, these findings contribute to a deeper elucidation of the molecular signaling mechanisms underlying Mn-induced apoptosis.
锰（Mn）是一种必需微量元素，已知其对维持许多生化和细胞反应的正常功能和调节至关重要。然而，在职业或环境环境中慢性暴露于高水平的 Mn 会导致其在大脑中积累，从而导致一种称为锰中毒的退行性脑疾病。星形胶质细胞是中枢神经系统中 Mn 的主要储存库，有几条证据表明这些细胞是锰中毒发展的主要参与者。在本研究中，我们使用大鼠星形细胞瘤 C6 细胞作为研究 Mn 神经毒性相关分子机制的敏感实验模型。我们的结果表明，C6 细胞在受到 Mn 刺激后会通过活性氧介导的细胞凋亡途径发生凋亡，该途径涉及半胱天冬酶-8 和线粒体介导的途径。暴露的细胞表现出典型的凋亡特征，如染色质浓缩、细胞收缩、细胞膜起泡、半胱天冬酶-3 激活和内源性底物多聚（ADP-核糖）聚合酶的半胱天冬酶特异性裂解。通过 FasL 水平升高、半胱天冬酶-8 激活和 Bid 裂解评估半胱天冬酶-8 依赖性途径的参与。线粒体途径的参与通过破坏线粒体膜电位、线粒体通透性转换孔的开放、细胞色素 c 释放、半胱天冬酶-9 激活和促凋亡 Bcl-2 家族蛋白的线粒体水平增加来证明。此外，我们的数据还首次表明线粒体碎片化在 Mn 诱导的细胞凋亡中发挥相关作用。综上所述，这些发现有助于更深入地阐明 Mn 诱导细胞凋亡的分子信号机制。
