Bioconjugation chemistry has been a powerful avenue in expanding the repertoire of druggable proteome, as well as in identifying new E3 ligases to support targeted protein degradation (TPD). However, a large fraction of proteome remains inaccessible with existing covalent probes. Herein, we incorporated various electron-withdrawing groups into styrene derivatives and identified β-nitrostyrene as a novel cysteine-targeting warhead for target discovery. Through phenotypic screening and chemoproteomics platforms, we identified new ligandable sites such as C96 of SND1, C110 of PTGES2, modulating cell proliferation in an acute myeloid leukemia cell line. Moreover, incorporation of this warhead into the BRD4 inhibitor (+)-JQ1 demonstrated that the covalent handle engages the novel E3 ligase tripartite motif-containing 28 (TRIM28) at Cys232 residue, thereby promoting the targeted degradation. Notably, when transplanted into other protein-targeting ligands, the β-nitrostyrene warhead effectively induced protein degradation of EGFRL858R/T790M/C797S, PDE5, BTK, LRRK2 and BCR-ABL/c-ABL without eliciting a hook effect. Importantly, the degraders demonstrate significantly enhanced anticancer effects compared to corresponding inhibitors. To our knowledge, this is the first report of small-molecular degraders engaging TRIM28 to support targeted protein degradation, and provides a rational pathway for design and development of potent monovalent degraders.

中文翻译：

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使用 β-硝基苯乙烯亲电试剂进行蛋白质组范围的配体和靶标发现：支持靶向蛋白质降解

生物偶联化学一直是扩展可成药蛋白质组库以及鉴定新的 E3 连接酶以支持靶向蛋白质降解 （TPD） 的有力途径。然而，现有的共价探针仍然无法接近大部分蛋白质组。在此，我们将各种吸电子基团掺入苯乙烯衍生物中，并确定 β-硝基苯乙烯是一种用于目标发现的新型半胱氨酸靶向弹头。通过表型筛选和化学蛋白质组学平台，我们确定了新的配体位点，如 SND1 的 C96、PTGES2 的 C110，调节急性髓性白血病细胞系中的细胞增殖。此外，将该弹头掺入 BRD4 抑制剂 （+）-JQ1 表明共价手柄在 Cys232 残基处与包含新型 E3 连接酶三方基序 28 （TRIM28） 啮合，从而促进靶向降解。值得注意的是，当移植到其他蛋白质靶向配体中时，β-硝基苯乙烯弹头有效地诱导了 EGFRL858R/T790M/C797S、PDE5、BTK、LRRK2 和 BCR-ABL/c-ABL 的蛋白质降解，而不会引发钩效应。重要的是，与相应的抑制剂相比，降解剂表现出显着增强的抗癌作用。据我们所知，这是小分子降解剂使用 TRIM28 支持靶向蛋白质降解的首次报道，并为设计和开发有效的单价降解剂提供了合理的途径。