探討鋅離子在多巴胺誘導對大鼠初代培養神經細胞焦亡中的影響

Study the Effects of Zn2+ in Dopamine-induced Pyroptosis in Primary-cultured Rat Embryonic Cortical Neurons

曾惠群(Hui-Chiun Tseng)

指導教授 ： 潘建源

國立臺灣大學/生命科學院/生命科學系/碩士(2020年)

https://doi.org/10.6342/NTU202003034

摘要

近年研究發現許多神經退化性疾病，如阿茲海默症、杭丁頓氏症和帕金森氏症等的發病機制與神經炎症 (neuroinflammation) 有關，並受到神經科學家們的廣泛關注。發炎反應啟動後，炎症小體 (inflammasomes) 的形成，會活化caspase-1，進而啟動細胞焦亡機制 (pyroptosis pathway)，釋放成熟的炎症細胞因子，包括IL-1β和IL-18至細胞外。我們過去的研究發現，多巴胺（dopamine, DA）會造成細胞內鋅離子濃度上升，誘導初代培養的大鼠胚胎皮質神經細胞死亡、及IL-1β基因表現增加。但是，神經炎症是否與DA誘導的細胞死亡有關尚不清楚。在本研究中，我們以初代培養的大鼠胚胎皮質神經細胞為模式，處理DA和二氫己啶 （dihydrexidine, DHX, 多巴胺D1受體促進劑），誘導細胞死亡。再以TPEN (鋅離子螯合劑)，MCC950 (細胞焦亡炎症小體抑制劑) 與VX765 (caspase 1抑製劑)，預處理培養的神經細胞，結果顯示這些抑制劑可減緩DA或DHX所造成的神經細胞死亡。而聚合酶鏈鎖反應和西方點墨法的結果顯示，DA或DHX處理會增加IL-1β基因與蛋白質的表現量 ; 而此增加，可以被TPEN所降低。而IL-1β的前處理，可以減少DA所造成的細胞死亡。這些結果顯示，細胞焦亡參與在D1受體與鋅離子所誘導的神經細胞死亡過程中，而過程中所釋放的IL-1β可提高神經細胞的存活率。因此如何控制細胞焦亡與IL-1β的釋放，將可提供神經退化性疾病新的治療策略。

關鍵字

多巴胺 ； 炎症小體 ； 神經退化性疾病 ； 神經炎症 ； 細胞焦亡 ； 鋅離子

並列摘要

Neuroinflammation has attracted much attention recently in the nervous system for its association with the pathogenesis of neurodegenerative disorders like Alzheimer's, Huntington’s, and Parkinson's diseases etc. The activation of inflammation will induce the formation of inflammasomes which activates the caspase-1 resulting in the induction of pyroptosis signaling pathway and the release of matured inflammatory cytokines including IL-1β and IL-18 into the extracellular milieu. Our previous reports have shown that dopamine (DA) elevates intracellular Zn2+ concentration which is a perquisite for DA-induced cell death and enhances the mRNA level of IL-1β in cultured rat embryonic cortical neurons. However, it is unclear that neuroinflammation is involved in DA-induced cell death. In this report, we treated the primary cultured rat embryonic cortical neurons with DA and dihydrexidine (DHX), a dopamine D1 receptor agonist, to induce cell death. Pretreating the cultured neurons with TPEN, a cell permeable Zn2+ chelator, MCC950, an inflammasome blocker, and VX765, a caspase 1 inhibitor could suppress cell death induced by dopamine and DHX. The PCR and Western blot analysis showed DA and DHX treatments increased the expression levels of IL-1 in culture neuron cells. In addition, pretreating the neurons with IL-1β suppressed the DA-induced cell death. These results suggest the involvement of pyroptosis in D1 receptor-Zn2+-cell death pathway and the released IL-1β enhances the cell survival. Therefore, controlling the pyroptosis and IL-1β level can be a new therapeutic strategy for neurodegenerative diseases.

並列關鍵字

dopamine ； inflammasome ； neurodegeneration ； neuroinflammation ； pyroptosis ； Zn2+

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