Involvement of histone acetyltransferase (HAT) in ethanol-induced acetylation of histone H3 in hepatocytes: potential mechanism for gene expression
Involvement of histone acetyltransferase (HAT) in ethanol-induced acetylation of histone H3 in hepatocytes: potential mechanism for gene expression
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DOI：
10.1152/ajpgi.00091.2005
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发表时间：
2005-12-01
影响因子：
4.5
通讯作者：
Shukla, SD
中科院分区：
文献类型：
--
作者：
Park, PH;Lim, RW;Shukla, SD
乙醇处理通过尚不清楚的机制增加肝脏中的基因表达。组蛋白乙酰化已显示诱导转录激活。我们研究了乙醇诱导的大鼠肝细胞组蛋白H3乙酰化的特点和机制。免疫细胞化学和免疫印迹分析表明，乙醇处理显着增加H3乙酰化在赖氨酸9与赖氨酸14，-18，和-23的影响可以忽略不计。大鼠体内急性给予酒精产生了与体外观察相同的结果。乙醇处理的肝细胞核提取物增加乙酰化H3肽在更大程度上比未经处理的细胞提取物，这表明乙醇增加组蛋白乙酰转移酶（HAT）的表达水平或比活性。不同H3肽的使用表明乙醇选择性地调节靶向H3-Lys 9的HAT。用乙酸盐（乙醇代谢物）处理也增加了H3-Lys 9的乙酰化，并以与乙醇相同的方式调节HAT，表明乙酸盐介导了乙醇对HAT的诱导作用。MEK（U 0126）和JNK（SP 600125）的抑制剂，但不是p38 MAPK抑制剂（SB 203580），抑制乙醇诱导的H3乙酰化。然而，U 0126和SP 600125没有显著影响乙醇诱导的对HAT的作用，表明ERK和JNK通过不涉及HAT调节的单独途径调节组蛋白乙酰化。染色质免疫沉淀试验表明，乙醇处理增加了与乙酰化H3-Lys 9的I类乙醇脱氢酶（ADH I）基因的关联。这些数据提供了乙醇通过调节HAT增加H3-Lys 9乙酰化的第一证据，并且组蛋白乙酰化可能是乙醇诱导的ADH I基因表达的机制的基础。
Ethanol treatment increases gene expression in the liver through mechanisms that are not clearly understood. Histone acetylation has been shown to induce transcriptional activation. We have investigated the characteristics and mechanisms of ethanol-induced histone H3 acetylation in rat hepatocytes. Immunocytochemical and immunoblot analysis revealed that ethanol treatment significantly increased H3 acetylation at Lys9 with negligible effects at Lys14, - 18, and - 23. Acute in vivo administration of alcohol in rats produced the same results as in vitro observations. Nuclear extracts from ethanol-treated hepatocytes increased acetylation in H3 peptide to a greater extent than extracts from untreated cells, suggesting that ethanol either increased the expression level or the specific activity of histone acetyltransferases ( HAT). Use of different H3 peptides indicated that ethanol selectively modulated HAT(s) targeting H3-Lys9. Treatment with acetate, an ethanol metabolite, also increased acetylation of H3-Lys9 and modulated HAT( s) in the same manner as ethanol, suggesting that acetate mediates the ethanol-induced effect on HAT. Inhibitors of MEK (U0126) and JNK (SP600125), but not p38 MAPK inhibitor (SB203580), suppressed ethanol-induced H3 acetylation. However, U0126 and SP600125 did not significantly affect ethanol-induced effect on HAT, suggesting that ERK and JNK regulate histone acetylation through a separate pathway( s) that does not involve modulation of HAT. Chromatin immunoprecipitation assay demonstrated that ethanol treatment increased the association of the class I alcohol dehydrogenase (ADH I) gene with acetylated H3-Lys9. These data provide first evidence that ethanol increases acetylation of H3-Lys9 through modulation of HAT( s) and that histone acetylation may underlie the mechanism for ethanol-induced ADH I gene expression.