不同浓度α- 突触核蛋白对培养SH-SY5Y细胞6- 羟基多巴胺神经毒性的双重作用
周明, 徐胜利*, 陈彪
α- 突触核蛋白(α-synuclein, α-SN)和泛素- 蛋白酶体系统(ubiquitin-proteasome system, UPS)在帕金森病发病过程中都起着重要作用，探讨两者在多巴胺能神经细胞死亡过程中的相互关系有重要意义。本文分别采用不同浓度的重组人α-SN、蛋白酶体活性抑制剂lactacystin 单独处理，或与多巴胺能神经细胞特异毒素6- 羟基多巴胺(6-OHDA)联合处理多巴胺能神经细胞系SH-SY5Y 细胞，然后检测细胞活性和蛋白酶体活性。结果显示，α-SN 依据浓度的不同而具有神经保护或神经毒性的双重作用。5 μmol/L 以下浓度的α-SN 可对抗6-OHDA 对SH-SY5Y 细胞的毒性，并有一定促增殖作用；10 μmol/L 以上浓度的α-SN 对细胞有毒性作用，并加重了6-OHDA 的细胞毒性。采用相应浓度的lactacystin 处理，获得与α-SN 处理相似的结果，而MEK1/2 特异抑制剂PD98059 干预则可完全阻断低浓度α-SN 和lactacystin 的神经保护作用。以上结果提示，不同浓度α-SN 对SH-SY5Y 细胞的6-OHDA 神经毒性的双重作用是通过抑制蛋白酶体活性实现的，而其对神经细胞的保护作用和MAPK 途径相关。
[Dual effects of different concentrations of α-synuclein on the neurotoxicity of 6-hydroxydopamine in SH-SY5Y cells.] [Ariticle in Chinese]
ZHOU Ming, XU Sheng-Li*, CHEN Biao
Department of Neurobiology, Institute of Geriatrics of Beijing, Xuanwu Hospital of the Capital University of Medical Sciences, Key Laboratory for Neurodegenerative Disease of Ministry of Education, Beijing 100053, China
α-synuclein (α-SN) has been postulated to play a pivotal role in the pathogenesis of Parkinson’s disease (PD). However, the physiological functions of α-SN and the molecular and cellular mechanisms underlying neuronal loss remain unclear. Recent studies suggest that α-SN plays dual roles of neuroprotection and neurotoxicity depending on its concentration or level of expression. In the present study, we explored the potential mechanisms for α-SN to regulate neuronal survival. α-SN at different concentrations (0.1 to 40 μmol/L) with or without 50 μmol/L 6-hydroxydopamine (6-OHDA) were added into the culture medium of the SH-SY5Y dopaminergic neural cells. The cell viability was measured on post-treatment day 1, 2 and 3. The activity of proteasome inhibited by α-SN was tested by a proteasome activity assay system after 2 h of α-SN treatment. According to the activity of proteasome inhibited by α-SN, the correlative dose of proteasome inhibitor––lactacystin (10 nmol/L to 5 μmol/L) with or without 50 μmol/L 6-OHDA were used and the cell viability was assayed on post-treatment day 1, 2 and 3. The results showed that α-SN played dual roles of neuroprotection and neurotoxicity depending on its concentration. At low concentration (0.1 to 5 μmol/L), α-SN promoted the proliferation and protected neurons against the neurotoxicity of 6-OHDA; in contrast, at high concentration (10 to 40 μmol/L), α-SN possessed cytotoxicity. The results of lactacystin treatment implied that the dual roles of α-SN were related to the moderate and strong inhibition of proteasome activity. The MEK1/2 specific inhibitor PD98059 completely blocked the protection of both α-SN and lactacystin, suggesting that MAPK pathway might be involved in the neuroprotection of α-SN.
通讯作者：徐胜利 E-mail: email@example.com
周明, 徐胜利, 陈彪. 不同浓度α- 突触核蛋白对培养SH-SY5Y细胞6- 羟基多巴胺神经毒性的双重作用[J]. 生理学报 2009; 61 (4): 324-330.
ZHOU Ming, XU Sheng-Li, CHEN Biao. [Dual effects of different concentrations of α-synuclein on the neurotoxicity of 6-hydroxydopamine in SH-SY5Y cells.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (4): 324-330 (in Chinese with English abstract).