(-)-Epicatechin, a Natural Flavonoid Compound, Protects Astrocytes Against Hemoglobin Toxicity via Nrf2 and AP-1 Signaling Pathways.
(-)-Epicatechin, a Natural Flavonoid Compound, Protects Astrocytes Against Hemoglobin Toxicity via Nrf2 and AP-1 Signaling Pathways.
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DOI：
10.1007/s12035-016-0271-y
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发表时间：
2017-12
影响因子：
5.1
通讯作者：
Wang J
中科院分区：
文献类型：
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作者：
Lan X;Han X;Li Q;Wang J
(−)-表儿茶素是一种脑透性天然产品，在绿茶和可可中含有高浓度。我们先前的研究表明，(−)-表儿茶素治疗通过体内核因子红系相关因子2(NRF2)信号通路减少出血性卒中损伤。然而，该化合物对氧化应激的调节和对血红蛋白诱导的星形胶质细胞损伤的保护作用机制尚不清楚。因此，我们在体外探索了这些保护作用的细胞和分子机制。从野生型小鼠和Nrf2基因敲除(KO)小鼠分离的原代星形胶质细胞用血红蛋白预处理，模拟脑出血(ICH)。用免疫印迹法、免疫印迹法、四甲基偶氮唑盐比色法和活性氧化应激(ROS)法检测(−)-EPATIC-CHIN的作用。(−)-表儿茶素可增加野生型星形胶质细胞中Nrf2的核积聚和胞浆中超氧化物歧化酶1的表达，但不增加Nrf2基因敲除的星形胶质细胞中超氧化物歧化酶1的表达。此外，(−)-表儿茶素处理没有改变血红蛋白暴露后野生型星形胶质细胞中的血红素加氧酶1(HO1)的表达，但它确实降低了类似处理的NRF2KO星形胶质细胞中HO1的表达。在野生型和NRF2KO星形胶质细胞中，(−)-表儿茶素均抑制磷酸化的jnk和jnk、c-jun和c-fos的核表达，表明(−)-表儿茶素抑制激活蛋白-1(AP-1)的活性不依赖于Nrf2。这些新的发现表明，(−)-表儿茶素通过上调NRF2和抑制AP-1的活性来保护星形胶质细胞免受血红蛋白毒性。这些细胞和分子效应可能部分解释了我们之前在脑出血动物模型中观察到的(−)-表儿茶素的脑保护作用。
(−)-Epicatechin is a brain-permeable, natural product found at high concentrations in green tea and cocoa. Our previous research has shown that (−)-epicat-echin treatment reduces hemorrhagic stroke injury via nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in vivo. However, the mechanism of action of this compound in modulation of oxidant stress and in protection against hemoglobin-induced astrocyte injury is unclear. Therefore, we explored the cellular and molecular mechanisms that underlie these protective effects in vitro. Mouse primary astrocytes isolated from wild-type mice and Nrf2 knockout (KO) mice were preconditioned with hemoglobin to simulate intracerebral hemorrhage (ICH) in vitro. Effects of (−)-epicate-chin were measured by Western blotting, immunostaining, MTT assay, and reactive oxidant stress (ROS) assay. (−)-Epicatechin increased Nrf2 nuclear accumulation and cytoplasmic levels of superoxide dismutase 1 (SOD1) in wild-type astrocytes but did not increase SOD1 expression in Nrf2 knockout (KO) astrocytes. Furthermore, (−)-epicatechin treatment did not alter heme oxygenase 1 (HO1) expression in wild-type astrocytes after hemoglobin exposure, but it did decrease HO1 expression in similarly treated Nrf2 KO astrocytes. In both wild-type and Nrf2 KO astrocytes, (−)-epicatechin suppressed phosphorylated JNK and nuclear expression of JNK, c-jun, and c-fos, indicating that inhibition of activator protein-1 (AP-1) activity by (−)-epicatechin is Nrf2-independent. These novel findings indicate that (−)-epicatechin protects astrocytes against hemoglobin toxicity through upregulation of Nrf2 and inhibition of AP-1 activity. These cellular and molecular effects may partially explain the cerebroprotection as we previously observed for (−)-epicatechin in animal models of ICH.