Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, 4222, Australia.
Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, 4111, Australia.
Neurotox Res. 2018 Feb;33(2):229-238. doi: 10.1007/s12640-017-9825-7. Epub 2017 Oct 24.
Intracellular aggregates of α-synuclein are the pathological hallmark of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), being linked to neurotoxicity. Multiple triggers of α-synuclein aggregation have been implicated, including raised copper. The potential protective role of the endogenous copper-/zinc-binding proteins, metallothioneins (MT), has been explored in relation to copper-induced α-synuclein aggregation. Up-regulated endogenous expression of MT was induced in SHSY-5Y cells by the synthetic glucocorticoid analogue, dexamethasone. After treatment to induce endogenous MT expression, immunofluorescence confocal microscopy was used to quantify protein aggregates in cells with/without copper treatment. MT induction resulted in significant (p < 0.01), dose-dependent up-regulation of MT expression and significant reduction in Cu-dependent α-synuclein intracellular aggregates (p < 0.01) that could be suppressed by MT-specific siRNA. Ubiquitous (MT-2) and brain-specific (MT-3) isoforms were investigated by transient transfection of the GFP-fusion proteins, observing equivalent α-synuclein aggregate suppression by each. These studies indicate MT induction could have potential in PD/DLB neuroprotective therapy by suppressing α-synuclein aggregation.
细胞内α-突触核蛋白的聚集是帕金森病（PD）和路易体痴呆（DLB）的病理标志，与神经毒性有关。已经涉及到多种导致α-突触核蛋白聚集的触发因素，包括铜的升高。金属硫蛋白（MT）等内源性铜/锌结合蛋白的潜在保护作用已在与铜诱导的α-突触核蛋白聚集相关的研究中得到了探索。合成糖皮质激素类似物地塞米松诱导 SHSY-5Y 细胞中内源性 MT 的上调。在用/不用铜处理后，用免疫荧光共聚焦显微镜定量分析细胞中的蛋白聚集体。MT 诱导导致 MT 表达显著（p<0.01）、剂量依赖性上调，并显著减少 Cu 依赖性α-突触核蛋白细胞内聚集体（p<0.01），而 MT 特异性 siRNA 可抑制这一作用。通过 GFP 融合蛋白的瞬时转染研究了普遍存在的（MT-2）和脑特异性（MT-3）同工型，观察到每个同工型对α-突触核蛋白聚集体的抑制作用相当。这些研究表明，通过抑制α-突触核蛋白聚集，MT 诱导可能在 PD/DLB 神经保护治疗中具有潜力。
