DNA binding, but not interaction with Bmal1, is responsible for DEC1-mediated transcription regulation of the circadian gene mPer1
DNA binding, but not interaction with Bmal1, is responsible for DEC1-mediated transcription regulation of the circadian gene mPer1
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DOI：
10.1042/bj20040592
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发表时间：
2004-09-15
影响因子：
4.1
通讯作者：
Yan, BF
中科院分区：
文献类型：
--
作者：
Li, YX;Song, XL;Yan, BF
DEC 1（在软骨细胞中差异表达1）和DEC 2是E-box结合转录因子，并表现出昼夜节律表达模式。最近，发现这两种蛋白质都抑制Clock/Bmal 1激活的E-box启动子（例如mPer 1）。酵母双杂交检测Bmal 1和德克斯之间的相互作用。假设DEC介导的对mPer 1启动子的抑制是通过与E-box元件结合并与Bmal 1相互作用实现的。在本研究中，我们报告说，E-box的结合，而不是Bmal 1的相互作用是负责观察到的镇压。在没有时钟/Bmal 1，DEC 1和DEC 2显着抑制mPer 1启动子报告，然而，DNA结合突变体显示没有抑制活性。类似地，DEC 1，而不是其DNA结合突变体，抑制Clock/Bmal 1诱导的激活。此外，DECR 58 P，一个DNA结合突变体与Bmal 1的相互作用，抑制mPer 1报告直接也没有时钟/Bmal 1诱导的激活，提供直接的证据表明，DNA结合，而不是Bmal 1的相互作用，是负责对mPer 1启动子的抑制。此外，破坏的Sp1网站在近端启动子mPer 1增加了DEC 1蛋白的阻遏。先前对小鼠DEC 2的研究表明，该因子与Sp1相互作用。这些发现表明DEC蛋白通过E-box结合和Sp1相互作用调节mPer 1的表达。昼夜节律系统的改变越来越被认为是疾病发生和进展的重要风险因素，Dec基因的表达会被环境刺激迅速诱导，并且在肿瘤组织中高度增加。因此，DEC基因的失调表达可能改变正常的昼夜节律，并在包括癌症在内的许多疾病的发病机制中起重要作用。
DEC1 (differentially expressed in chondrocytes 1) and DEC2 are E-box-binding transcription factors and exhibit a circadian expression pattern. Recently, both proteins were found to repress the Clock/Bmal1-activated E-box promoters (e.g. mPer1). Yeast two-hybrid assay detected interactions between Bmal1 and DECs. It was hypothesized that DEC-mediated repression on the mPer1 promoter is achieved by binding to E-box elements and interacting with Bmal1. In the present study, we report that E-box binding rather than Bmal1 interaction is responsible for the observed repression. In the absence of Clock/Bmal1, both DEC1 and DEC2 markedly repressed the mPer1 promoter reporter; however, DNA-binding mutants showed no repressive activity. Similarly, DEC1, but not its DNA-binding mutants, repressed the Clock/Bmal1-induced activation. In addition, DECR58P, a DNA-binding mutant with Bmal1 interactivity, repressed neither the mPer1 reporter directly nor the Clock/Bmal1-induced activation, providing direct evidence that DNA binding, rather than Bmal1 interactions, is responsible for the repression on the mPer1 promoter. Furthermore, disruption of the Sp1 site in the proximal promoter of mPer1 increased the repression of DEC1 proteins. Previous studies with mouse DEC2 showed that this factor interacts with Sp1. These findings suggest that DEC proteins regulate the expression of mPer1 through E-box binding and Sp1 interaction. Alterations on circadian systems are increasingly recognized as important risk factors for disease initiation and progression, and the expression of Dec genes is rapidly induced by environmental stimuli and is highly increased in tumour tissues. Therefore de-regulated expression of DEC genes probably alters normal circadian rhythms and contributes significantly to the pathogenesis of many diseases including cancer.