Comparative genome analysis identifies the vitamin D receptor gene as a direct target of p53-mediated transcriptional activation
Comparative genome analysis identifies the vitamin D receptor gene as a direct target of p53-mediated transcriptional activation
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DOI：
10.1158/0008-5472.can-05-2562
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发表时间：
2006-05-01
期刊：
影响因子：
11.2
通讯作者：
Tokino, Takashi
中科院分区：
文献类型：
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作者：
Maruyama, Reo;Aoki, Fumio;Tokino, Takashi
p53是人类肿瘤形成中最常突变的肿瘤抑制基因，并编码转录辅激活因子。因此，p53靶基因的鉴定是理解p53在肿瘤发生中的作用的关键。为了鉴定新的p53靶基因，我们首先使用比较基因组学方法来鉴定人和小鼠基因组中保守的p53结合序列。我们假设保守的潜在p53结合序列更可能是功能性的。使用严格的过滤程序，32个基因被新确定为推定的p53靶点，并通过逆转录-PCR和实时PCR证实了它们在人类癌细胞中对p53的反应性。其中，我们专注于维生素D受体（VDR）基因，因为维生素D3最近已被用于人类肿瘤的化学预防。VDR是由p53以及其他几个p53家族成员诱导的，染色质免疫沉淀分析表明，p53蛋白在体内与VDR基因的保守内含子序列结合。将VDR引入细胞导致已知为p53靶点的几个基因的诱导和结直肠癌细胞生长的抑制。此外，p53以维生素D3依赖的方式诱导VDR靶基因。我们的计算机模拟方法是一种强有力的方法，用于鉴定在人类和其他生物体中保守的功能性p53结合位点和p53靶基因，并进一步了解p53在肿瘤发生中的功能。
p53 is the most frequently mutated tumor suppressor gene in human neoplasia and encodes a transcriptional coactivator. Identification of p53 target genes is therefore key to understanding the role of p53 in tumorigenesis. To identify novel p53 target genes, we first used a comparative genomics approach to identify p53 binding sequences conserved in the human and mouse genome. We hypothesized that potential p53 binding sequences that are conserved are more likely to be functional. Using stringent filtering procedures, 32 genes were newly identified as putative p53 targets, and their responsiveness to p53 in human cancer cells was confirmed by reverse transcription-PCR and real-time PCR. Among them, we focused on the vitamin D receptor (VDR) gene because vitamin D3 has recently been used for chemoprevention of human tumors. VDR is induced by p53 as well as several other p53 family members, and analysis of chromatin immunoprecipitation showed that p53 protein binds to conserved intronic sequences of the VDR gene in vivo. Introduction of VDR into cells resulted in induction of several genes known to be p53 targets and suppression of colorectal cancer cell growth. In addition, p53 induced VDR target genes in a vitamin D3-dependent manner. Our in silico, approach is a powerful method for identification of functional p53 binding sites and p53 target genes that are conserved among humans and other organisms and for further understanding the function of p53 in tumorigenesis.