Oerlemans Guido J M, van den Oetelaar Maxime C M, van den Elzen Siebe P, Brunsveld Luc
Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute of Complex Molecular Systems, Technische Universiteit Eindhoven, 5612 AZ Eindhoven, The Netherlands.
ACS Chem Biol. 2025 Sep 19;20(9):2308-2317. doi: 10.1021/acschembio.5c00475. Epub 2025 Sep 10.
The orphan nuclear receptor NR2F6 (Nuclear Receptor subfamily 2 group F member 6) is an emerging therapeutic target for cancer immunotherapy. Upregulation of NR2F6 expression in tumor cells has been linked to proliferation and metastasis, while in immune cells NR2F6 inhibits antitumor T-cell responses. Small molecule modulation of NR2F6 activity might therefore be a novel strategy in cancer treatment, benefiting from this dual role of NR2F6. However, there are no molecular strategies available for targeting NR2F6, hampered among others by lack of structural insights and appropriate biochemical assays. To overcome these challenges, several noncanonical nuclear receptor coregulator peptide motifs were identified to be constitutively recruited to the NR2F6 ligand binding domain (LBD). Co-crystallization of the NR2F6 LBD with a peptide from the coregulator Nuclear Receptor Binding SET Domain Protein 1 (NSD1) enabled, for the first time, the structural elucidation of the unliganded (apo) form of NR2F6. This revealed an autorepressed, homodimeric LBD conformation in which helix 12 folds over the canonical coregulator binding site, generating an alternative contact surface for NSD1 binding. Screening of a focused library of covalent NR probes identified compounds that preferentially target a cysteine residue near the NSD1 binding site, inhibiting NR2F6 coregulator recruitment. Combined, these results provide structural insights into the ligand-independent transcriptional activity of NR2F6 and may serve as a starting point for the development of novel NR2F6 modulators.
孤儿核受体NR2F6（核受体亚家族2组F成员6）是癌症免疫治疗中一个新兴的治疗靶点。肿瘤细胞中NR2F6表达的上调与增殖和转移有关，而在免疫细胞中，NR2F6抑制抗肿瘤T细胞反应。因此，小分子调节NR2F6活性可能是癌症治疗中的一种新策略，受益于NR2F6的这种双重作用。然而，目前尚无针对NR2F6的分子策略，缺乏结构见解和合适的生化分析等因素阻碍了相关研究。为了克服这些挑战，人们发现了几种非典型核受体共调节肽基序可组成性地募集到NR2F6配体结合域（LBD）。NR2F6 LBD与共调节因子核受体结合SET结构域蛋白1（NSD1）的一种肽的共结晶首次实现了NR2F6无配体（脱辅基）形式的结构解析。这揭示了一种自抑制的同二聚体LBD构象，其中螺旋12折叠在经典共调节因子结合位点上，为NSD1结合产生了一个替代的接触表面。对一个聚焦的共价NR探针文库进行筛选，鉴定出优先靶向NSD1结合位点附近一个半胱氨酸残基的化合物，从而抑制NR2F6共调节因子的募集。综合这些结果，为NR2F6的非配体依赖性转录活性提供了结构见解，并可能作为开发新型NR2F6调节剂的起点。
