Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, College of Pharmacy, University of Minnesota, 717 Delaware Street, Minneapolis, Minnesota 55414, United States.
Moffitt Cancer Center, Drug Discovery Department, 12902 Magnolia Drive, Tampa, Florida 33612, United States.
J Med Chem. 2022 Aug 11;65(15):10441-10458. doi: 10.1021/acs.jmedchem.2c00453. Epub 2022 Jul 22.
Bromodomain and extraterminal domain (BET) proteins are important regulators of gene transcription and chromatin remodeling. BET family members BRD4 and BRDT are validated targets for cancer and male contraceptive drug development, respectively. Due to the high structural similarity of the acetyl-lysine binding sites, most reported inhibitors lack intra-BET selectivity. We surmised that protein-protein interactions induced by bivalent inhibitors may differ between BRD4 and BRDT, conferring an altered selectivity profile. Starting from nonselective monovalent inhibitors, we developed cell-active bivalent BET inhibitors with increased activity and selectivity for BRDT. X-ray crystallographic and solution studies revealed unique structural states of BRDT and BRD4 upon interaction with bivalent inhibitors. Varying spacer lengths and symmetric vs unsymmetric connections resulted in the same dimeric states, whereas different chemotypes induced different dimers. The findings indicate that the increased intra-BET selectivity of bivalent inhibitors is due to the differential plasticity of BET bromodomains upon inhibitor-induced dimerization.
溴结构域和末端结构域（BET）蛋白是基因转录和染色质重塑的重要调节剂。BET 家族成员 BRD4 和 BRDT 分别是癌症和男性避孕药研发的有效靶点。由于乙酰化赖氨酸结合位点的高度结构相似性，大多数报道的抑制剂缺乏 BET 内选择性。我们推测，二价抑制剂诱导的蛋白-蛋白相互作用可能在 BRD4 和 BRDT 之间存在差异，从而赋予不同的选择性特征。我们从非选择性单价抑制剂出发，开发了具有更高活性和 BRDT 选择性的细胞活性双价 BET 抑制剂。X 射线晶体学和溶液研究揭示了 BRDT 和 BRD4 与双价抑制剂相互作用时独特的结构状态。不同的间隔长度和对称与非对称连接导致相同的二聚体状态，而不同的化学型诱导不同的二聚体。这些发现表明，二价抑制剂增加的 BET 内选择性是由于抑制剂诱导的二聚化过程中 BET 溴结构域的不同可塑性所致。
