School of Life Sciences, Jilin University, Changchun City, Jilin, China.
National Engineering Laboratory for AIDS Vaccine, Jilin University, Changchun City, Jilin, China.
FEBS J. 2018 Aug;285(16):3026-3040. doi: 10.1111/febs.14592. Epub 2018 Jul 4.
The restriction of Yin Yang 1 (YY1) at BRCA2 and CDKN1A/p21-interacting protein (BCCIP) transcriptional start site (TSS) proximal region in several human cancer cell lines was found by analyzation of ChIP-Seq database from UCSC Genome Browser (http://genome.ucsc.edu). However, whether the stabilization of YY1 by BCCIP impacts its recruitment in the BCCIP promoter region is unclear. Here, we present evidence that transcriptional regulation of YY1 on BCCIP is closely related to YY1 stability in HCT116 human colon cancer cells. YY1 stabilization was in turn regulated by BCCIP, suggesting the existence of a BCCIP-YY1 feedback loop in regulating BCCIP transcription by the YY1. Overexpression of BCCIP stabilized YY1 while knockdown of BCCIP reduced YY1 protein level. In addition, direct interaction between YY1 and BCCIP was confirmed by coimmunoprecipitation approach. Also, the N-terminus region of BCCIP, including the internal conserved domain (ICD), was responsible for binding with the amino acid 146-270 of YY1. More importantly, YY1 stability was related to the BCCIP/ICD domain-mediated YY1 ubiquitination pathway. Moreover, a limited BCCIP promoter region containing YY1 binding site (CCGCCATC) was tightly associated with the pGL4-BCCIP-Luc luciferase activity. In ChIP assays, shBCCIP lentiviral-mediated YY1 instability decreased recruitment of the YY1 at BCCIP TSS proximal region, which could not be restored by YY1 overexpression. Furthermore, knockdown of YY1 inhibited the binding of BCCIP itself at BCCIP promoter region proximal to TSS, demonstrating that transcriptional regulation of the YY1 on BCCIP can be modulated by BCCIP itself in a YY1-dependent fashion.
通过分析 UCSC 基因组浏览器（http://genome.ucsc.edu）的 ChIP-Seq 数据库，发现 Yin Yang 1 (YY1) 在几个人类癌细胞系的 BRCA2 和 CDKN1A/p21 相互作用蛋白（BCCIP）转录起始位点（TSS）近端区域受到限制。然而，BCCIP 对 YY1 的稳定作用是否影响其在 BCCIP 启动子区域的募集尚不清楚。在这里，我们提供的证据表明，YY1 对 BCCIP 的转录调控与其在 HCT116 人结肠癌细胞中的稳定性密切相关。YY1 的稳定作用反过来又受到 BCCIP 的调节，这表明在通过 YY1 调节 BCCIP 转录过程中存在 BCCIP-YY1 反馈回路。BCCIP 的过表达稳定了 YY1，而 BCCIP 的敲低则降低了 YY1 蛋白水平。此外，通过共免疫沉淀方法证实了 YY1 和 BCCIP 之间的直接相互作用。此外，BCCIP 的 N 端区域，包括内部保守结构域（ICD），负责与 YY1 的氨基酸 146-270 结合。更重要的是，YY1 的稳定性与 BCCIP/ICD 结构域介导的 YY1 泛素化途径有关。此外，含有 YY1 结合位点（CCGCCATC）的有限 BCCIP 启动子区域与 pGL4-BCCIP-Luc 荧光素酶活性紧密相关。在 ChIP 测定中，shBCCIP 慢病毒介导的 YY1 不稳定性降低了 YY1 在 BCCIP TSS 近端区域的募集，而 YY1 的过表达不能恢复这种募集。此外，YY1 的敲低抑制了 BCCIP 自身在靠近 TSS 的 BCCIP 启动子区域近端的结合，表明 YY1 对 BCCIP 的转录调控可以通过 BCCIP 自身以 YY1 依赖的方式进行调节。
