Carnosic acid protects neuronal HT22 Cells through activation of the antioxidant-responsive element in free carboxylic acid- and catechol hydroxyl moieties-dependent manners
Carnosic acid protects neuronal HT22 Cells through activation of the antioxidant-responsive element in free carboxylic acid- and catechol hydroxyl moieties-dependent manners
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DOI：
10.1016/j.neulet.2008.01.079
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发表时间：
2008-04-01
影响因子：
2.5
通讯作者：
Shirasawa, Takuji
中科院分区：
文献类型：
--
作者：
Satoh, Takumi;Izumi, Masanori;Shirasawa, Takuji
在以前的研究中，我们发现肉桂酸(CA)通过激活Keap1/Nrf2途径来保护皮质神经元，该途径的激活是由KEAP1蛋白的关键半胱氨酸硫醇被亲电的苯醌类型的CA的S烷基化启动的[T.Satoh，K.Kosaka，K.Itch，A.Kobayashi，M.Yamamoto，Y.Shimojo，C.Kitajima，J.Cui，J.Kamins，S.Okamoto，T.Shirasawa，S.A.Lipton，肉豆酸，一种儿茶酚型亲电化合物，通过靶向Keap1上的半胱氨酸的S烷基化激活Keap1/Nrf2通路，在体外和体内保护神经元。J Neurochem.，在出版中]。在目前的研究中，我们使用神经细胞系HT22细胞来测试可能更适合在体内使用的CA衍生物，因为像CA这样的电泳体可能在到达预期的目标之前与其他分子反应。CA和肌醇对HT22细胞的谷氨酸氧化毒性具有保护作用。CA激活第二相基因的转录抗氧化反应元件，包括血红素加氧酶-1、依赖于NADPH的苯醌氧化还原酶和γ-谷氨酰半胱氨酸连接酶，所有这些都通过调节细胞的氧化还原来提供神经保护。这一结果被CA显著增加谷胱甘肽水平的结果所证实。我们合成了一系列类似物，其中CA在邻苯二酚羟基部分酯化，以防止邻苯二酚氧化为苯二酚形式，或在这些部分与其碳酸酯化，以阻止CA转化为卡诺醇。在这两种情况下，只有在烷基被细胞内的酯酶去除后，转化和氧化才能发生。因此，作为Keap1/Nrf2途径激活剂的最有效的活性形式--苯酚型CA将在细胞内产生。然而，这两种化学调节都没有增强神经保护作用，可能是因为增加了亲脂性。这些结果表明，CA的神经保护作用需要游离酸和儿茶酚羟基的共同作用。因此，CA的亲水性可能是其神经保护作用的一个重要特征。(C)2008年，爱思唯尔爱尔兰有限公司出版。
In a previous study, we found that carnosic acid (CA) protected cortical neurons by activating the Keap1/Nrf2 pathway, which activation was initiated by S-alkylation of the critical cysteine thiol of the Keap1 protein by the "electrophilic" quinone-type of CA [T. Satoh, K. Kosaka, K. Itch, A. Kobayashi, M. Yamamoto, Y. Shimojo, C. Kitajima, J. Cui, J. Kamins, S. Okamoto, T. Shirasawa, S.A. Lipton, Carnosic acid, a catechol-type electrophilic compound, protects neurons both in vitro and in vivo through activation of the Keap1/Nrf2 pathway via S-alkylation of targeted cysteines on Keap1. J Neurochem., in press]. In the present study, we used HT22 cells, a neuronal cell line, to test CA derivatives that might be more suitable for in vivo use, as an electrophile like CA might react with other molecules prior to reaching its intended target. CA and carnosol protected the HT22 cells against oxidative glutamate toxicity. CA activated the transcriptional antioxidant-responsive element of phase-2 genes including hemeoxygenase-1, NADPH-dependent quinone oxidoreductase, and gamma-glutamyl cysteine ligase, all of which provide neurorprotection by regulating cellular redox. This finding was confirmed by the result that CA significantly increased the level of glutathione. We synthesized a series of its analogues in which CA was esterified at its catechol hydroxyl moieties to prevent the oxidation from the catechol to quinone form or esterified at those moieties and its carbonic acid to stop the conversion from CA to carnosol. In both cases, the conversion and oxidation cannot occur until the alkyl groups are removed by an intracellular esterase. Thus, the most potent active form as the activator of the Keap1/Nrf2 pathway, the quinone-type CA, will be produced inside the cells. However, neither chemical modulation potentiated the neruroprotective effects, possibly because of increased lipophilicity. These results suggest that the neuroprotective effects of CA critically require both free carboxylic acid and catechol hydroxyl moieties. Thus, the hydrophilicity of CA might be a critical feature for its neuroprotective effects. (C) 2008 Published by Elsevier Ireland Ltd.