Department of Structural and Chemical Biology, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1677, New York, New York 10029, United States.
J Am Chem Soc. 2011 Feb 23;133(7):2040-3. doi: 10.1021/ja107761h. Epub 2011 Jan 27.
The CREB binding protein (CBP) is a human transcriptional coactivator consisting of several conserved functional modules, which interacts with distinct transcription factors including nuclear receptors, CREB, and STAT proteins. Despite the importance of CBP in transcriptional regulation, many questions regarding the role of its particular domains in CBP functions remain unanswered. Therefore, developing small molecules capable of selectively modulating a single domain of CBP is of invaluable aid at unraveling its prominent activities. Here we report the design, synthesis, and biological evaluation of conformationally restricted peptides as novel modulators for the acetyl-lysine binding bromodomain (BRD) of CBP. Utilizing a target structure-guided and computer-aided rational design approach, we developed a series of cyclic peptides with affinity for CBP BRD significantly greater than those of its biological ligands, including lysine-acetylated histones and tumor suppressor p53. The best cyclopeptide of the series exhibited a K(d) of 8.0 μM, representing a 24-fold improvement in affinity over that of the linear lysine 382-acetylated p53 peptide. This lead peptide is highly selective for CBP BRD over BRDs from other transcriptional proteins. Cell-based functional assays carried out in colorectal carcinoma HCT116 cells further demonstrated the efficacy of this compound to modulate p53 stability and function in response to DNA damage. Our results strongly argue that these CBP modulators can effectively inhibit p53 transcriptional activity by blocking p53K382ac binding to CBP BRD and promoting p53 instability by changes of its post-translational modification states, a different mechanism than that of the p53 inhibitors reported to date.
CREB 结合蛋白（CBP）是一种人类转录共激活因子，由几个保守的功能模块组成，与包括核受体、CREB 和 STAT 蛋白在内的不同转录因子相互作用。尽管 CBP 在转录调控中非常重要，但关于其特定结构域在 CBP 功能中的作用的许多问题仍未得到解答。因此，开发能够选择性调节 CBP 单一结构域的小分子对于阐明其主要活性具有不可估量的帮助。在这里，我们报告了构象受限肽作为 CBP 乙酰化赖氨酸结合溴结构域（BRD）新型调节剂的设计、合成和生物学评价。我们利用基于靶结构的计算机辅助合理设计方法，开发了一系列对 CBP BRD 具有显著亲和力的环状肽，其亲和力明显大于其生物配体，包括赖氨酸乙酰化组蛋白和肿瘤抑制因子 p53。该系列中最好的环肽的 K(d)为 8.0 μM，与线性赖氨酸 382 乙酰化 p53 肽相比，亲和力提高了 24 倍。该先导肽对 CBP BRD 的选择性高于其他转录蛋白的 BRD。在结直肠癌细胞 HCT116 中进行的基于细胞的功能测定进一步证明了该化合物能够调节 p53 稳定性和功能，以响应 DNA 损伤。我们的结果强烈表明，这些 CBP 调节剂可以通过阻止 p53K382ac 与 CBP BRD 的结合有效抑制 p53 转录活性，并通过改变其翻译后修饰状态促进 p53 不稳定性，这是与迄今为止报道的 p53 抑制剂不同的机制。
