Up-Regulation of the μ-Opioid Receptor Gene Is Mediated through Chromatin Remodeling and Transcriptional Factors in Differentiated Neuronal Cells
Up-Regulation of the μ-Opioid Receptor Gene Is Mediated through Chromatin Remodeling and Transcriptional Factors in Differentiated Neuronal Cells
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DOI：
10.1124/mol.110.064311
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发表时间：
2010-07-01
影响因子：
3.6
通讯作者：
Loh, Horace H.
中科院分区：
文献类型：
--
作者：
Hwang, Cheol Kyu;Kim, Chun Sung;Loh, Horace H.
吗啡的作用主要通过Mu阿片受体(MOR)介导。在P19胚胎癌细胞的神经分化过程中，MOR的表达上调，表观遗传学改变在MOR上调中起重要作用。这项研究通过研究几个因素对重塑的染色质基因座的招募或解离来研究依赖于分化的MOR染色质改变的基础。染色质免疫沉淀分析表明转录激活因子Sp1和染色质重塑因子BRG1和BAF155被募集到该启动子上，以及抑制物[组蛋白去乙酰酶、mSin3A、BRM和甲基-CpG结合蛋白2(MeCP2)]的解离。组蛋白修饰(乙酰化、诱导组蛋白H3-lys4甲基化和减少H3-lys9甲基化)在该启动子上被一致检测到。Sp1的过表达显著增强了MOR启动子的活性，组蛋白去乙酰化酶抑制剂曲古抑素A也增加了启动子的活性。在体外，启动子的DNA CpG甲基化部分阻断了Sp1因子的结合，但诱导了MeCP2的结合。免疫共沉淀研究还发现了内源性MeCP2与Sp3相互作用的新证据，但与Sp1的相互作用较弱。总之，这些结果表明，在神经元分化过程中，MeCP2和DNA甲基化通过染色质重塑因子(BRG1和BAF155)介导了MOR启动子从紧凑状态到允许转录因子进入的构象的重塑。激活转录因子的后续招募
The effects of morphine are mediated mainly through the mu opioid receptor (MOR). Expression of the MOR is upregulated during neuronal differentiation in P19 embryonal carcinoma cells and epigenetic changes play an important role in MOR up-regulation. This study investigates the basis for differentiation-dependent alterations of MOR chromatin by studying the recruitment or dissociation of several factors to the remodeled chromatin locus. Chromatin immunoprecipitation assays were used to demonstrate the recruitment of the transcriptional activator Sp1 and the chromatin remodeling factors Brg1 and BAF155 to this promoter, as well as the dissociation of repressors [histone deacetylases, mSin3A, Brm, and methyl-CpG-binding protein 2 (MeCP2)]. Histone modifications (acetylation, induction of histone H3-lys4 methylation, and reduction of H3-lys9 methylation) were consistently detected on this promoter. Overexpression of Sp1 strongly enhanced MOR promoter activity, and the histone deacetylase inhibitor trichostatin A also increased promoter activity. In vitro DNA CpG-methylation of the promoter partially blocked binding of the Sp1 factor but induced MeCP2 binding. Coimmunoprecipitation studies also found novel evidence of an endogenous MeCP2 interaction with Sp3 but a weaker interaction with Sp1. Overall, the results suggest that during neuronal differentiation, MeCP2 and DNA methylation mediate remodeling of the MOR promoter by chromatin remodeling factors (Brg1 and BAF155) from a compacted state to a conformation allowing access for transcriptional factors. Subsequent recruitment of the activating transcription factor