调节Hsp70功能的小分子共价探针研究

The Hsp70 family of molecular chaperones plays a key role in the protein quality control system and participates in multiple cellular activities including the stress response. Hsp70 has been identified as an important hallmark of diverse diseases including cancer, neurodegenerative diseases and immune related diseases, and is recognised as a potential therapeutic target. Given the success in clinical trials of anti-tumor drugs targeting Hsp90, there is increasing interest in developing small molecular probes and inhibitors of Hsp70, although there are still no clinically-approved drugs targeting Hsp70. Compared with traditional inhibitors, targeted covalent inhibitors with moderate reactivity have advantages including stronger and more durable inhibition efficiency, higher specificity and lower side effects (toxicity). We plan to develop covalent probes targeting the Cys residues of Hsp70 through three approaches: 1) high-throughput screening from covalent compound libraries of our collaborator; 2) modification of published non-covalent Hsp70 inhibitors by adding a covalent modifying group; 3) selection from Hsp70 inhibitors that possess a covalent modifying group but with unclear mechanism of action. Having selected appropriate probes, we will continue to study the detailed mechanism of how they affect the structure and function of Hsp70, and try to solve the structure of the complex of Hsp70 with the probe. We will also examine the inhibition effect in cells and explore the mechanism and downstream events of such effects. This study will not only lay a foundation for developing drugs targeting Hsp70, but will also provide a powerful tool for further research into the structure, function and mechanism of Hsp70.

Hsp70是蛋白质质量控制体系的核心分子伴侣，参与应激反应等多种细胞活动，与肿瘤、神经退行性疾病和免疫性疾病等多种疾病密切相关，是这些疾病治疗的重要靶标。继Hsp90为靶标的抗肿瘤药物进入临床实验后，Hsp70的小分子探针和抑制剂研究日趋高涨，但仍无临床药物。相比普通抑制剂，反应性适中的靶向共价抑制剂效果更强更持久，特异性更好，毒性更低。我们拟通过三种途径发展针对Hsp70的Cys的共价探针：一，从合作者已有的共价修饰化合物库中筛选；二，改造现有Hsp70的非共价抑制剂，使之具备共价修饰基团；三，从机制不明但带有共价修饰基团的已有Hsp70抑制剂中发掘。进而深入研究它们影响Hsp70结构和功能的详细机制，获得Hsp70和探针的复合物结构，在细胞水平阐明其抑制效应和机制。本研究将不仅为针对Hsp70的药物开发提供前期基础，而且为深入研究Hsp70的复杂功能和机制提供强有力的工具。

Hsp70是蛋白质质量控制体系的核心分子伴侣，参与应激反应等多种细胞活动，与肿瘤、神经退行性疾病和免疫性疾病等多种疾病密切相关，是这些疾病治疗的重要靶标。继以Hsp90为靶标的抗肿瘤药物进入临床实验后，Hsp70的小分子探针和抑制剂研究日趋高涨，但仍无临床药物。相比普通抑制剂，反应性适中的靶向共价抑制剂效果更强更持久，特异性更好，毒性更低。我们通过三种途径发展针对Hsp70的Cys残基的共价探针：一，从合作者已有的共价修饰化合物库中筛选；二，发现已知的作用机制不清楚的肿瘤抑制剂PES是Hsp70的共价抑制剂；三，通过改造修饰PES探针发展更多的具有不同特点的Hsp70的共价探针，得到了二十多种PES衍生物。我们发现PES通过和HspA1A/B的C末端SBDα中的两个Cys发生亲核加成反应，使SBDα发生去折叠从而封闭HspA1A/B的底物结合域，不可逆的关闭HspA1A/B的分子伴侣功能，抑制其活性。我们还发现PES和巯基的亲核加成反应在细胞内可能广泛存在，如PES和GSH可以反应。PES在细胞内有多个靶标，通过多途径杀伤细胞，PES和HspA1A/B的共价修饰反应并不具特异性。为了深入研究PES的细胞毒性机制，我们发展了能发生点击化学反应的PES衍生物PESA；为了获得针对HspA1A/B的C末端SBDα中的两个Cys的特异性共价修饰探针，我们发展了和GSH低反应性、而和HspA1A/B高反应性的PES衍生物PYS和AmPES；此外我们还得到了一个到目前为止和HspA1A/B的巯基反应活性最高的PES衍生物PES-NO2。这些研究结果不仅为针对Hsp70的药物开发提供前期基础，而且为深入研究Hsp70的复杂功能和机制提供强有力的工具。这些PES衍生物可继续向成药方向发展。