亚型和底物选择性的O-GlcNAc转移酶抑制剂的发现

O-GlcNAc transferase (OGT), an essential mammalian enzyme, catalyses the transfer of N-acetylglucosamine (GlcNAc) from UDP-N-acetylglucosamine to hydroxyl groups of serines and threonines (Ser/Thr) in proteins. O-GlcNAcylation is widely located in both cytoplasm and nucleus. This kind of protein post-translational modification is involved in the regulation of many cellular signaling pathways and closely associated with the occurrence and development of numerous critical illnesses. However, reports of OGT inhibitors are very limited and there are no commercial available OGT inhibitors with high activitity and high selectivity, which has impeded the research of function and regulation of O-GlcNAcylation. In this project, target-guided synthesis avoids the dependence of high-throughput activity assays. With the concept of combinatorial chemistry, the novel strategy "tethering in situ click chemistry" employs OGT as a template for self-assembling inhibitors with subtype- and substrate-selectivity from complementary building blocks. The further clarification of physiological/pathological roles of different OGT isoforms and selective recognition of different substrates will establish the foundation for the development of therapeutic drugs for relevant diseases.

O-GlcNAc转移酶（OGT）是一种至关重要的哺乳动物酶，其将单个N-乙酰氨基葡萄糖（GlcNAc）以O-糖苷键连接到蛋白质的丝氨酸和苏氨酸（Ser/Thr）羟基上。O-GlcNAc 糖基化在细胞质和细胞核中广泛地存在，这种蛋白质翻译后修饰对细胞内的许多信号通路具有调节作用，并与多种重大疾病的发生和发展密切相关。然而，针对OGT抑制剂的研究报道十分有限，目前还没有商品化的高活性、高选择性OGT抑制剂，阻碍了对O-GlcNAc糖基化的功能和调节机制的研究。在本项目中，以OGT为模板，利用实验室自行发展的“捆绑式原位点击化学”策略使合适的构建模块自组装，避免了高通量活性测定方法的依赖，以组合化学的理念，靶标导向合成亚型和底物选择性的OGT抑制剂。进一步阐明不同亚型OGT的生理和病理作用以及选择性识别不同底物的方式，为发展相关疾病的治疗性药物奠定了基础。

O-GlcNAc转移酶（O-GlcNAc transferase，OGT）是一种关键酶，其参与细胞核和细胞质内的动态O-GlcNAc糖基化。发现细胞可渗透的OGT抑制剂对于阐明O-GlcNAc糖基化的功能和调节机制具有重要意义，为发展相关疾病的治疗性药物奠定了基础。本课题组前期工作通过“捆绑式原位点击化学（Tethering in situ click chemistry, TISCC）”开发了两种细胞渗透性的非竞争性OGT抑制剂1-（4-乙酰氨基苯基）-4-（萘-2-基）-1H-1,2,3-三氮唑（APNT）和1-（4-乙酰氨基苯基）-4-（1,1’-联苯-4-基）-1H-1,2,3-三氮唑（APBT）。这两种抑制剂能够在细胞中降低O-GlcNAc糖基化水平，而没有明显的细胞毒性。APNT有较好的抑制活性，IC50值为66.7 ± 0.8 μM，因此，将其作为先导物开发新结构类型的酶抑制剂。一方面，通过传统的原位点击化学拓展APNT衍生物的结合位点，对60种炔基构建模块进行再次筛选发现了一种更有潜力的OGT抑制剂。另一方面，通过药物化学对APNT进行结构修饰，使用不同的基团替代三氮唑来连接苯环和萘环以改善抑制剂的溶解度；对苯环/萘环上取代基的种类和位置进行探索。本研究为OGT抑制剂的进一步结构优化提供了一个全新骨架的先导化合物，并为调节O-GlcNAc糖基化水平提供了一个潜在的工具分子。