Stabilization of tumor necrosis factor alpha mRNA by chronic ethanol: role of A + U-rich elements and p38 mitogen-activated protein kinase signaling pathway.
Stabilization of tumor necrosis factor alpha mRNA by chronic ethanol: role of A + U-rich elements and p38 mitogen-activated protein kinase signaling pathway.
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DOI：
10.1074/jbc.m107181200
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发表时间：
2001-11
期刊：
影响因子：
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通讯作者：
R. Kishore;M. McMullen;Laura E. Nagy
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文献类型：
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作者：
R. Kishore;M. McMullen;Laura E. Nagy
慢性乙醇引起的肿瘤坏死因子α(TNFpha)表达增加与酒精性肝病的发病机制有关。然而，乙醇增加肿瘤坏死因子α水平的分子机制还没有得到很好的描述。利用从饲喂含乙醇饲料的大鼠的Kupffer细胞和暴露于乙醇的小鼠巨噬细胞系RAW264.7的培养，我们证明了慢性乙醇暴露导致脂多糖(LPS)诱导的TNFpha表达增强。通过核连续实验检测，慢性乙醇对脂多糖诱导的肿瘤坏死因子α转录速率无影响，但慢性乙醇可延长肿瘤坏死因子α基因的半衰期。慢性乙醇还增强了内毒素诱导的Kupffer细胞和RAW264.7细胞中p38丝裂原活化蛋白(MAP)激酶的激活。SB203580特异性地抑制Kupffer细胞中p38 MAPK的激活，或在RAW264.7细胞中过表达显性负p38 MAPK，阻断了乙醇介导的TNFpha mRNA的稳定。此外，使用嵌合报告结构，我们已经表明，在TNFpha mRNA的3‘-非翻译区中，富A+U元件不足以给予乙醇介导的对TNFpha mRNA的稳定。
Increased expression of tumor necrosis factor alpha (TNFalpha) in response to chronic ethanol has been implicated in the pathogenesis of alcoholic liver disease. However, the molecular mechanisms by which ethanol increases the levels of TNFalpha are not well characterized. Utilizing Kupffer cells isolated from rats fed an ethanol containing diet and a murine macrophage cell line, RAW264.7, exposed to ethanol in culture, we have demonstrated that exposure to chronic ethanol results in an enhanced expression of lipopolysaccharide (LPS)-induced TNFalpha. While chronic ethanol had no effect on the rate of LPS-induced TNFalpha transcription as measured by nuclear run-on experiments, TNFalpha mRNA half-life was increased by chronic ethanol. Chronic ethanol also potentiated the activation of LPS-induced p38 mitogen-activated protein (MAP) kinase in Kupffer cells, as well as in RAW264.7 cells. Specific inhibition of p38 MAP kinase activation by SB203580 in Kupffer cells or by overexpression of dominant negative p38 MAP kinase in RAW264.7 cells blocked ethanol-mediated TNFalpha mRNA stabilization. Furthermore, using chimeric reporter constructs, we have shown that A + U-rich elements in the 3'-untranslated region of TNFalpha mRNA are not sufficient to impart ethanol-mediated stabilization on TNFalpha mRNA.