Department of Food and Nutrition, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Korea.
Neurochem Res. 2013 Aug;38(8):1561-71. doi: 10.1007/s11064-013-1057-5. Epub 2013 Apr 27.
Mammalian AMP-activated protein kinase (AMPK) acts as a metabolite-sensing protein kinase in multiple tissues. Recent studies have shown that AMPK activation also regulates intracellular signaling pathways involved in cellular survival and apoptosis. Previously, we have reported that AMPK activation alleviates the endoplasmic reticulum (ER) stress-mediated neurotoxicity and tau hyperphosphorylation caused by palmitate. Therefore, we investigated whether AMPK activation alleviates ER stress-mediated neurotoxicity in SH-SY5Y human neuroblastoma cells incubated with homocysteine. Regulation of AMPK activity by isoflavone was also determined to investigate the underlying mechanism of its neuroprotective effect. Treatment of SH-SY5Y human neuroblastoma cells with N (1)-(β-D-ribofuranosyl)-5-aminoimidazole-4-carboxamide (AICAR), a pharmacological activator of AMPK, significantly protected cells against cytotoxicity imposed by tunicamycin and homocysteine. Homocysteine significantly suppressed AMPK activation, which was alleviated by AICAR. We observed a significant inhibition of the unfolded protein response by AICAR in cells incubated with homocysteine, suggesting a protective role of AMPK activation against ER stress-mediated neurotoxicity. AICAR also significantly reduced tau hyperphosphorylation by inactivating glycogen synthase kinase-3β and c-Jun N-terminal kinase in cells incubated with homocysteine. Furthermore, treatment of cells with soy isoflavone, genistein and daidzein significantly activated AMPK, which was repressed by tunicamycin and homocysteine. Therefore, our results suggest that AMPK activation by isoflavone as well as AICAR alleviates homocysteine-mediated neurotoxicity in SH-SY5Y cells.
哺乳动物的 AMP 激活蛋白激酶（AMPK）作为一种代谢物感应蛋白激酶，在多种组织中发挥作用。最近的研究表明，AMPK 的激活还调节参与细胞存活和凋亡的细胞内信号通路。先前，我们已经报道 AMPK 的激活可减轻棕榈酸引起的内质网（ER）应激介导的神经毒性和 tau 过度磷酸化。因此，我们研究了 AMPK 的激活是否可减轻同型半胱氨酸孵育的 SH-SY5Y 人神经母细胞瘤细胞中 ER 应激介导的神经毒性。还通过异黄酮调节 AMPK 活性，以研究其神经保护作用的潜在机制。用 N（1）-（β-D-呋喃核糖基）-5-氨基咪唑-4-甲酰胺（AICAR）处理 SH-SY5Y 人神经母细胞瘤细胞，即 AMPK 的药理学激活剂，可显著保护细胞免受衣霉素和同型半胱氨酸引起的细胞毒性。同型半胱氨酸显著抑制 AMPK 的激活，而 AICAR 可缓解这种抑制。我们观察到 AICAR 可显著抑制孵育有同型半胱氨酸的细胞中的未折叠蛋白反应，提示 AMPK 的激活可防止 ER 应激介导的神经毒性。AICAR 还通过使糖原合酶激酶-3β和 c-Jun N 末端激酶失活，显著降低了孵育有同型半胱氨酸的细胞中的 tau 过度磷酸化。此外，用大豆异黄酮、染料木黄酮和大豆苷元处理细胞可显著激活 AMPK，而衣霉素和同型半胱氨酸则抑制其激活。因此，我们的结果表明，异黄酮和 AICAR 通过激活 AMPK 可减轻 SH-SY5Y 细胞中的同型半胱氨酸介导的神经毒性。
