Molecular Chaperones and Small Molecules

抽象的。这个项目的目标是了解伴侣介导的分子机制， 蛋白质质量控制(PQC)。热休克蛋白70(Hsp70)是已知与客户蛋白结合并使 让它们降级的“决定”。Hsp70是如何做出这个选择的？为什么有时会出问题呢？ 严重的神经退行性疾病，包括脊髓延髓肌萎缩症(SBMA)和 额颞性痴呆(FTD)与Hsp70系统未能充分清除 受损客户，如多谷氨酰胺扩展雄激素受体(PolyQ-AR)和突变体 微管相关蛋白tau(MAPT/tau)。我们设想热休克蛋白70的机械知识- 介导的PQC将发现可能用于恢复正常蛋白质动态平衡的新药物靶点 并最终治疗这些疾病。事实上，在前一个筹资周期中，我们取得了重大进展 在理解这一中心机制之谜方面的进展。具体来说，我们的结果表明 Hsp70与PolyQ-AR或MAPT/tau的长时间结合是一个招募E3泛素连接酶的“信号”， 芯片，并触发降级级联。这种新模式只是通过我们的开发才得以解锁的 在HSP70系统中选择性地控制蛋白质-蛋白质相互作用(PPI)的新化学探针。 在R01的过程中，我们已经将这些试剂运往全球60多个实验室，使 许多PQC模型中的重要发现。现在，在这场竞争性的更新中，我们很兴奋地提出 下一代重要的机械性问题和PPI目标。在初步研究中，我们 发现NEF家族的辅助伴侣结合Hsp70来对抗营业额，而Dna JA2似乎可以 参与客户选择。因此，我们将开发新的化学和遗传工具来揭示：(SA1) Hsp70-NEF复合体如何控制多聚Q-AR和MAPT/tau的亲和力(SA2) Hsp70-DnaJA2的客户招募和(SA3)更广泛的伴侣网络如何协作互动 和这些客户在一起。在每个目标中，我们将部署创新的化学和生化方法，加上 以核磁共振为基础的结构方法。我们预计，这项工作将对我们的 了解热休克蛋白70亚网络如何维持蛋白质的动态平衡。

Abstract. The goal of this project is to understand the molecular mechanisms of chaperone-mediated, protein quality control (PQC). Heat shock protein 70 (Hsp70) is known to bind client proteins and make the “decision” to degrade them. How does Hsp70 make this choice? Why does it sometimes go wrong? Severe neurodegenerative disorders, including spinobulbar muscular atrophy (SBMA) and frontotemporal dementia (FTD), are associated with a failure of the Hsp70 system to adequately clear damaged clients, such as polyglutamine-expanded androgen receptor (polyQ-AR) and mutants of microtubule-associated protein tau (MAPT/tau). We envision that mechanistic knowledge of Hsp70- mediated PQC will uncover new drug targets that might be used to restore normal protein homeostasis and, ultimately, treat these diseases. Indeed, in the previous funding cycle, we made substantial progress in understanding this central mechanistic mystery. Specifically, our results suggest that prolonged binding of Hsp70 to polyQ-AR or MAPT/tau is a “signal” that recruits the E3 ubiquitin ligase, CHIP, and triggers a degradation cascade. This new model was only unlocked through our development of new chemical probes that selectively control protein-protein interactions (PPIs) in the Hsp70 system. In the course of this R01, we have shipped these reagents to 60+ laboratories worldwide, enabling important discoveries in many PQC models. Now, in this competitive renewal, we are excited to propose the next-generation of important mechanistic questions and PPI targets. In preliminary studies, we discovered that NEF family co-chaperones bind Hsp70 to antagonize turnover, while DnaJA2 seems to be involved in client selection. Thus, we will develop new chemical and genetic tools to reveal: (SA1) how the Hsp70-NEF complex controls affinity for polyQ-AR and MAPT/tau, (SA2) the mechanisms of client recruitment by Hsp70-DnaJA2 and (SA3) how broader chaperone networks collaborate to interact with these clients. In each aim, we will deploy innovative chemical and biochemical approaches, coupled with NMR-based structural methods. We anticipate that this work will have a fundamental impact on our understanding of how Hsp70 sub-networks maintain protein homeostasis.