Farr Susan A, Ripley Jessica L, Sultana Rukhsana, Zhang Zhaoshu, Niehoff Michael L, Platt Thomas L, Murphy M Paul, Morley John E, Kumar Vijaya, Butterfield D Allan
Research & Development Service, VA Medical Center, St. Louis, MO, USA.
Department of Chemistry, Center of Membrane Sciences, Sanders Brown Center on Aging, University of Kentucky, Lexington, KY 40506, USA.
Free Radic Biol Med. 2014 Feb;67:387-95. doi: 10.1016/j.freeradbiomed.2013.11.014. Epub 2013 Dec 16.
Glycogen synthase kinase (GSK)-3β is a multifunctional protein that has been implicated in the pathological characteristics of Alzheimer's disease (AD), including the heightened levels of neurofibrillary tangles, amyloid-beta (Aβ), and neurodegeneration. In this study we used 12-month-old SAMP8 mice, an AD model, to examine the effects GSK-3β may cause regarding the cognitive impairment and oxidative stress associated with AD. To suppress the level of GSK-3β, SAMP8 mice were treated with an antisense oligonucleotide (GAO) directed at this kinase. We measured a decreased level of GSK-3β in the cortex of the mice, indicating the success of the antisense treatment. Learning and memory assessments of the SAMP8 mice were tested post-antisense treatment using an aversive T-maze and object recognition test, both of which observably improved. In cortex samples of the SAMP8 mice, decreased levels of protein carbonyl and protein-bound HNE were measured, indicating decreased oxidative stress. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a transcription factor known to increase the level of many antioxidants, including glutathione-S transferase (GST), and is negatively regulated by the activity of GSK-3β. Our results indicated the increased nuclear localization of Nrf2 and level of GST, suggesting the increased activity of the transcription factor as a result of GSK-3β suppression, consistent with the decreased oxidative stress observed. Consistent with the improved learning and memory, and consistent with GSK-3b being a tau kinase, we observed decreased tau phosphorylation in brain of GAO-treated SAMP8 mice compared to that of RAO-treated SAMP8 mice. Lastly, we examined the ability of GAO to cross the blood-brain barrier and determined it to be possible. The results presented in this study demonstrate that reducing GSK-3 with a phosphorothionated antisense against GSK-3 improves learning and memory, reduces oxidative stress, possibly coincident with increased levels of the antioxidant transcriptional activity of Nrf2, and decreases tau phosphorylation. Our study supports the notion of GAO as a possible treatment for AD.
糖原合酶激酶（GSK）-3β是一种多功能蛋白，与阿尔茨海默病（AD）的病理特征有关，包括神经原纤维缠结、β淀粉样蛋白（Aβ）水平升高和神经退行性变。在本研究中，我们使用12月龄的AD模型SAMP8小鼠，来研究GSK-3β可能对与AD相关的认知障碍和氧化应激产生的影响。为了抑制GSK-3β的水平，我们用针对该激酶的反义寡核苷酸（GAO）处理SAMP8小鼠。我们检测到小鼠皮层中GSK-3β水平降低，表明反义治疗取得成功。反义治疗后，使用厌恶T迷宫和物体识别测试对SAMP8小鼠的学习和记忆进行评估，结果二者均有明显改善。在SAMP8小鼠的皮层样本中，检测到蛋白质羰基和蛋白质结合的HNE水平降低，表明氧化应激减轻。核因子红细胞2相关因子2（Nrf2）是一种转录因子，已知其可增加包括谷胱甘肽-S转移酶（GST）在内的多种抗氧化剂的水平，并且受GSK-3β活性的负调控。我们的结果表明Nrf2的核定位增加以及GST水平升高，这表明由于GSK-3β受到抑制，转录因子的活性增强，这与观察到的氧化应激减轻一致。与学习和记忆改善一致，并且鉴于GSK-3β是一种tau激酶，我们观察到与随机寡核苷酸（RAO）处理的SAMP8小鼠相比，GAO处理的SAMP8小鼠脑内tau磷酸化水平降低。最后，我们检测了GAO穿过血脑屏障的能力，并确定这是可行的。本研究结果表明，用针对GSK-3的硫代磷酸反义寡核苷酸降低GSK-3水平可改善学习和记忆、减轻氧化应激，这可能与Nrf2抗氧化转录活性水平升高同时发生，并降低tau磷酸化。我们的研究支持GAO作为AD可能治疗方法的观点。
