Identification and functional characterization of a primate‐specific E2F1 binding motif regulating MCPH1 expression
Identification and functional characterization of a primate‐specific E2F1 binding motif regulating MCPH1 expression
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DOI：
10.1111/j.1742-4658.2011.08441.x
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
Lei Shi;B. Su
中科院分区：
文献类型：
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作者：
Lei Shi;B. Su
MCPH1（也称为BRIT1）是已知的常染色体隐性遗传性原发性小头畸形（小头综合征）的基因之一，表明其在脑发育中的重要作用。MCPH1与E2F1等转录因子的相互作用是激活细胞周期检查点、DNA修复和凋亡所必需的。然而，MCPH1调控的分子机制目前尚不清楚。在这里，我们克隆了人类MCPH1启动子，我们确定了一个新的E2F1结合基序位于近端启动子区的MCPH1。电泳迁移率改变和启动子分析表明，E2F1可以通过直接结合到E2F1基序刺激MCPH1的转录。过量表达E2F1导致MCPH1转录上调，敲低内源性E2F1导致MCPH1启动子活性抑制。令人惊讶的是，脊椎动物物种的序列比较表明，所鉴定的E2F1结合基序是灵长类特异性的，与先前观察到的灵长类动物中MCPH1蛋白序列的快速进化一致。我们认为，在灵长类动物进化过程中，MCPH1在其启动子中获得了一个新的E2F1结合基序，这可能是一种平行机制，与灵长类动物中快速的蛋白质序列变化一起起作用，并最终促成了灵长类动物进化和人类起源过程中的脑增大。
MCPH1 (also named BRIT1) is one of the known genes responsible for autosomal recessive primary microcephaly (small head syndrome), suggesting its important role in brain development. The interaction of MCPH1 with transcriptional factors like E2F1 is required for the activation of cell cycle checkpoint, DNA repair and apoptosis. However, the molecular mechanism of MCPH1 regulation is currently unclear. Here, we cloned the human MCPH1 promoter and we identified a novel E2F1 binding motif located in the proximal promoter region of MCPH1. The experiments using electrophoretic mobility shift and promoter assays showed that E2F1 could stimulate MCPH1 transcription by direct binding to the E2F1 motif. Overexpression of E2F1 led to the upregulation of MCPH1 transcription, and knocking down the endogenous E2F1 resulted in the inhibition of the MCPH1 promoter activity. Surprisingly, sequence comparison of vertebrate species suggested that the identified E2F1 binding motif is primate specific, consistent with the previous observation of rapid evolution of MCPH1 protein sequence in primates. We propose that during primate evolution MCPH1 has acquired a novel E2F1 binding motif in its promoter which may act as a parallel mechanism, acting together with the rapid protein sequence changes in primates, and eventually contributed to brain enlargement during primate evolution and human origin.