Graduate School of Science, Chiba University, Japan.
FEBS J. 2014 Jul;281(14):3126-37. doi: 10.1111/febs.12848. Epub 2014 Jun 6.
TATA-binding protein-like protein (TLP) binds to transcription factor IIA (TFIIA) with high affinity, although the significance of this binding is poorly understood. In this study, we investigated the role of TFIIA in transcriptional regulation of the p21(Waf1/Cip1) (p21) gene. It has been shown that TLP is indispensable for p53-activated transcription from an upstream TATA-less promoter of the p21 gene. We found that mutant TLPs having decreased TFIIA-binding ability exhibited weakened transcriptional activation function for the upstream promoter. Activity of the upstream promoter was enhanced considerably by an increased amount of TFIIA in a p53-dependent manner, whereas activity of the TATA-containing downstream promoter was enhanced only slightly. TFIIA potentiated the upstream promoter additively with TLP. Although TFIIA is recruited to both promoters, activity of the upstream promoter was much more dependent on TFIIA. Recruitment of TFIIA and TLP to the upstream promoter was augmented in etoposide-treated cells, in which the amount of TFIIA-TLP complex is increased, and TFIIA-reactive TLP was required for the recruitment of both factors. It was confirmed that etoposide-stimulated transcription depends on TLP. We also found that TFIIA-reactive TLP acts to decrease cell growth rate, which can be explained by interaction of the p21 promoter with the transcription factors that we examined. The results of the present study suggest that the upstream TATA-less promoter of p21 needs TFIIA and TFIIA-reactive TLP for p53-dependent transcriptional enhancement.
TATA 结合蛋白样蛋白（TLP）与转录因子 IIA（TFIIA）具有高亲和力结合，尽管这种结合的意义尚未完全理解。在这项研究中，我们研究了 TFIIA 在 p21（Waf1/Cip1）（p21）基因转录调控中的作用。已经表明，TLP 对于 p53 激活的 p21 基因上游无 TATA 启动子的转录是必不可少的。我们发现，TFIIA 结合能力降低的突变 TLPs 表现出减弱的上游启动子转录激活功能。上游启动子的活性通过 p53 依赖性方式显著增强，而含有 TATA 的下游启动子的活性仅略有增强。TFIIA 与 TLP 协同增强上游启动子的活性。尽管 TFIIA 被募集到两个启动子上，但上游启动子的活性更依赖于 TFIIA。TFIIA 和 TLP 在上游启动子上的募集在依托泊苷处理的细胞中增强，其中 TFIIA-TLP 复合物的量增加，并且 TFIIA 反应性 TLP 是募集两种因子所必需的。证实了依托泊苷刺激的转录依赖于 TLP。我们还发现，TFIIA 反应性 TLP 作用于降低细胞生长速率，这可以通过与我们研究的转录因子相互作用来解释 p21 启动子。本研究的结果表明，p21 的上游无 TATA 启动子需要 TFIIA 和 TFIIA 反应性 TLP 来进行 p53 依赖性转录增强。
