Role of the intronic enhancer in tumor necrosis factor-mediated induction of manganous superoxide dismutase
Role of the intronic enhancer in tumor necrosis factor-mediated induction of manganous superoxide dismutase
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DOI：
10.1074/jbc.m303431200
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发表时间：
2003-06-27
影响因子：
4.8
通讯作者：
Boss, JM
中科院分区：
文献类型：
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作者：
Guo, Z;Boekhoudt, GH;Boss, JM
锰超氧化物歧化酶（Mn-SOD）是肿瘤坏死因子（TNF）诱导的基因产物，在清除线粒体内产生的超氧阴离子中起重要作用。两个调控区域，转录起始位点上游的近端启动子区（PPR）和内含子2内的tnf响应元件（TNFRE）负责Mn-SOD的表达。为了了解这些区域如何促进Mn-SOD的转录，我们对小鼠Mn-SOD基因进行了定量逆转录pcr、染色质免疫沉淀和体内核酸酶敏感性测定。这些实验表明Sp1和核因子(NF)-kappaB p65是TNF诱导Mn-SOD所必需的。Sp1组成性地结合PPR，而NF-kappaB p65和C/ ebp - β仅在TNF治疗后结合TNFRE。C/ ebp - β与TNFRE的结合依赖于NF-kappaB p65的存在。TNF处理后，TNFRE内的染色质结构更容易被核酸酶消化。这种可访问性需要Sp1和NF-kappaB p65。用组蛋白去乙酰化抑制剂处理细胞，或用表达共激活子的质粒瞬时转染细胞，可增强Mn-SOD的表达。PPR和TNFRE的组蛋白H3和H4的乙酰化需要NF-kappaB p65结合。综上所述，这些数据表明PPR和TNFRE之间的交流涉及在Mn-SOD对TNF的诱导过程中染色质重塑和组蛋白乙酰化。
Manganous superoxide dismutase (Mn-SOD), a tumor necrosis factor (TNF)-inducible gene product, plays an important role in removing superoxide anions produced inside mitochondria. Two regulatory regions, the proximal promoter region (PPR), which is upstream from the transcription initiation site, and the TNF-responsive element (TNFRE), which is inside intron 2, are responsible for Mn-SOD expression. To understand how each of these regions contributes to the transcription of Mn-SOD, quantitative reverse transcription-PCR, chromatin immunoprecipitations, and in vivo nuclease sensitivity assays were performed on the murine Mn-SOD gene. These assays demonstrate that Sp1 and nuclear factor (NF)-kappaB p65 are required for Mn-SOD induction by TNF. Sp1 bound the PPR constitutively, whereas NF-kappaB p65 and C/EBP-beta bound the TNFRE only after TNF treatment. Binding of C/EBP-beta to the TNFRE was dependent on the presence of NF-kappaB p65. The chromatin structure within the TNFRE became more accessible to nuclease digestion after TNF treatment. This accessibility required Sp1 and NF-kappaB p65. Treatment of cells with an inhibitor of histone deacetylation, or transient transfection with coactivator-expressing plasmids, enhanced the expression of Mn-SOD. NF-kappaB p65 binding was required for acetylation of histones H3 and H4 at the PPR and the TNFRE. Together, these data suggest communication between the PPR and the TNFRE which involves chromatin remodeling and histone acetylation during the induction process of Mn-SOD in response to TNF.