Vitamin E (α-tocopherol) attenuates cyclo-oxygenase 2 transcription and synthesis in immortalized murine BV-2 microglia
Vitamin E (α-tocopherol) attenuates cyclo-oxygenase 2 transcription and synthesis in immortalized murine BV-2 microglia
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DOI：
10.1042/bj20021358
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发表时间：
2003-03-01
影响因子：
4.1
通讯作者：
Sattler, W
中科院分区：
文献类型：
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作者：
Egger, T;Schuligoi, R;Sattler, W
环氧合酶2(COX-2)是早期小胶质细胞中对致炎刺激反应上调的基因之一。在本研究中，我们研究了神经系统的基本成分α-生育酚(α-TOX)对内毒素(LPS)刺激的小鼠BV-2小胶质细胞COX-2活化的影响。在未经刺激的BV-2细胞中，COX-2mRNA和蛋白几乎检测不到，但对内毒素有强烈的上调作用。在脂多糖刺激的BV-2细胞中，COX-2蛋白合成的激活涉及细胞外信号调节激酶1/2(ERK1/2)和p38丝裂原活化蛋白激酶(MAPK)通路的激活，并且对蛋白激酶C(PKC)抑制剂星形孢子素和白屈菜红碱以及MAP/ERK激酶1/2抑制剂PD98059和U0126敏感。BV-2细胞在内毒素刺激前加入ATOCH可显著上调蛋白磷酸酶2A(PP2A)活性，下调PKC活性、ERK1/2磷酸化和核因子kappaB(NFkappaB)活性。结果，在加入α-TocH的细胞中，COX-2蛋白水平和前列腺素E-2产量显著降低。α-TocH对PKC活性的影响可被两种PP抑制剂花盏花素A和冈田酸逆转。综上所述，我们的结果表明，alphaTocH激活了小胶质细胞的PP2A活性，从而抑制了脂多糖激活的PKC/ERK/NFkappaB信号级联反应，从而显著抑制了COX-2蛋白的合成。这些体外结果表明，AlphaTocH可以诱导与中枢神经系统急性或慢性炎症条件相关的通路的静止。
One of the immediate early microglial genes that are up-regulated in response to proinflammatory stimuli is cyclo-oxygenase 2 (COX-2). In the present study, we have investigated the effects of alpha-tocopherol (alphaTocH), an essential constituent of the nervous system, on the activation of COX-2 in lipopolysaccharide (LPS)-stimulated mouse BV-2 microglia. In unstimulated BV-2 cells, COX-2 mRNA and protein were almost undetectable but were strongly up-regulated in response to LPS. Activation of COX-2 protein synthesis in LPS-stimulated BV-2 cells involved activation of the extracellular-signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) pathway and was sensitive to the protein kinase C (PKC) inhibitors staurosporine and chelerythrine, and the MAP kinase/ERK kinase 1/2 inhibitors PD98059 and U0126. Supplementation of BV-2 cells with aTocH before LPS stimulation resulted in pronounced up-regulation of protein phosphatase 2A (PP2A) activity, down-regulation of PKC activity, ERK1/2 phosphorylation and nuclear factor kappaB (NFkappaB) activation. As a result, COX-2 protein levels and prostaglandin E-2 production were significantly lower in alphaTocH-supplemented cells. The effects of alphaTocH on PKC activity Could be reverted by calyculin A and okadaic acid, two PP inhibitors. In summary, our results suggest that alphaTocH activates microglial PP2A activity and thereby silences an LPS-activated PKC/ERK/NFkappaB signalling cascade resulting in significantly attenuated COX-2 protein synthesis. These in vitro results imply that alphaTocH could induce quiescence to pathways that are associated with acute or chronic inflammatory conditions in the central nervous system.