UVB upregulates the bax promoter in immortalized human keratinocytes via ROS induction of Id3.
UVB upregulates the bax promoter in immortalized human keratinocytes via ROS induction of Id3.
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DOI：
10.1111/j.1600-0625.2008.00801.x
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发表时间：
2009-04
影响因子：
3.6
通讯作者：
Rosenthal DS
中科院分区：
文献类型：
--
作者：
Trabosh VA;Daher A;Divito KA;Amin K;Simbulan-Rosenthal CM;Rosenthal DS
Id 3属于HLH转录因子的分化抑制因子家族，在增殖、分化和凋亡中起重要作用。我们发现，身份证3，而不是身份证2或身份证1，介导的UVB敏化永生化角质形成细胞诱导caspase 9依赖性凋亡。在目前的研究中，定量PCR分析揭示了一个时间依赖性的增加Id 3 mRNA诱导UVB，依赖于活性氧。UVB在早期时间点上调Id 3的启动子活性，但不上调Id 2，如报告基因测定所示，并且还稳定Id 3 mRNA，将其半衰期从10分钟增加至约60分钟。我们接下来检查了与UVB诱导的Id 3上调相关的下游事件，并研究了UVB或Id 3的异位表达对bax启动子活性的影响。在bax启动子中的调节元件介导的UVB和Id 3的转录激活，在p53的情况下，进行了鉴定。Bax启动子缺失分析表明，UVB的转录激活涉及一个738 bp的区域上游的Bax的转录起始位点。模仿UVB的影响，异位表达的Id 3也上调bax mRNA和激活这738 bp的片段。转录结合位点的突变分析进一步表明，在738 bp的片段中发现的E盒区域的点突变，但不是在174 bp的片段中，完全废除了Id 3和UVB诱导的bax启动子活性，从而证实了Id 3和UVB介导的Id 3上调激活bax启动子的重要性。这些结果表明，ROS上调Id 3通过E-box结合因子解除bax的抑制的机制。
Id3 belongs to the Inhibitor of differentiation family of HLH transcription factors, important in proliferation, differentiation, and apoptosis. We showed that Id3, but not Id2 or Id1, mediates the UVB-sensitization of immortalized keratinocytes by inducing caspase 9-dependent apoptosis. In the current study, quantitative PCR analysis revealed a time-dependent increase in Id3 mRNA induced by UVB, dependent on reactive oxygen species. UVB upregulated promoter activity of Id3, but not Id2, at early time points, as shown by reporter assays, and also stabilized Id3 mRNA, increasing its half-life from 10 to ~60 minutes. We next examined downstream events related to UVB-induced Id3 upregulation and investigated the effects of UVB or ectopic expression of Id3 on bax promoter activity. Regulatory elements in the bax promoter that mediate transcriptional activation by UVB and Id3, in the absence of p53, were identified. Bax promoter deletion analysis revealed that transcriptional activation by UVB involves a 738-bp region upstream from the transcription start site of bax. Mimicking the effects of UVB, ectopic expression of Id3 also upregulated bax mRNA and activated this 738-bp fragment. Mutational analysis of the transcription binding sites further showed that point mutations of the E-box region found in the 738-bp fragment, but not in a 174-bp fragment, completely abolished Id3- and UVB-inducible bax promoter activity, thus confirming the importance of Id3 and UVB-mediated Id3 upregulation in activating the bax promoter. These results suggest a mechanism whereby ROS upregulation of Id3 relieves repression of bax via E-box-binding factors.
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影响因子：
6.5
作者：
Frost, C;Williams, G;Green, A
通讯作者：
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影响因子：
3
作者：
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DOI：
10.1016/j.saa.2005.10.013
发表时间：
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影响因子：
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作者：
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