Yeast prions and Hsp70 chaperones

酵母朊病毒和 Hsp70 伴侣

• 批准号: 10008651
• 负责人: Daniel Masison
• 金额: $ 72.7万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10008651
• 关键词: Affect; Amyloid; Amyloidosis; Awareness; Binding; Cell Wall; Cell physiology; Cells; Cellular Stress; Client; Disease; Drug Targeting; Enzymes; Eukaryotic Cell; Family member; Goals; Guanine Nucleotide Exchange Factors; Heat-Shock Proteins 70; Impairment; Mediating; Modeling; Molecular; Molecular Chaperones; Nucleotides; Organism; Pathology; Play; Point Mutation; Prions; Process; Protein Conformation; Proteins; Quality Control; Reaction; Regulation; Role; Source; Specificity; Structure; System; To specify; Work; Yeasts; cell growth; in vivo; insight; protein folding; protein function; proteostasis; response; targeted treatment; therapeutic candidate; yeast prion

Organisms encode multiple Hsp70s to increase capacity to regulate abundance of Hsp70 in accordance with need and to provide a range of distinct Hsp70 functions for carrying out many different tasks within cells. We constructed a yeast system to evaluate Hsp70s from any source and have found that all of the functionally redundant essential yeast Hsp70s possess distinct activities. We are continuing to use this system to investigate how Hsp70s within and across species influence propagation of amyloid in vivo and act in cellular protein quality control (PQC) processes. The wide range of responses that prions have to alterations of Hsp70s and their co-chaperones provides a sensitive way to investigate even subtle functional distinctions among highly redundant Hsp70s and an approach to uncover the underlying mechanisms. Hsp70s act by binding and releasing client substrate proteins and co-chaperones interact with Hsp70s to regulate their activity. The large number of co-chaperones that act on different steps of the Hsp70 reaction cycle can cooperate to provide both a broad range of function and fine-tuning of Hsp70 activity to specify its proper functions in defined roles in cells. After Hsp70 binds client proteins, nucleotide exchange factors (NEFs) facilitate release of the substrates and restarting of the binding cycle. One aspect of our work focuses on determining how functions of Hsp70s are mediated by ways they cooperate with NEFs. In pursuing whether different functions of nearly identical Hsp70s Ssa1 and Ssa2 could be due to differential interactions with NEFs, we uncovered unexpected Hsp70-independent roles of an Hsp70 NEF in degradation of gluconeogenic enzymes and in cell wall integrity. These findings raise new awareness about roles of such conserved NEFs in yeast and possibly other eukaryotic cells. Altering abundance or function of Hsp70 can moderate pathology in models of protein folding disorders, while in the same models reducing chaperone activity can exacerbate, or alone even cause pathology. Hsp70 is therefore a promising therapeutic candidate for amyloid and other protein folding disorders and it is being evaluated intensively as a drug target. Altering Hsp70 co-chaperones also moderates pathology in several models of amyloid and other protein folding disorders. Our work toward understanding what underlies specificity in activities of functionally redundant Hsp70s can help guide decisions about which Hsp70-family members would be most useful for such applications, or identify potential problems that could arise due to ways different Hsp70s respond differently to specific compounds. Overall our work provides insight into functions of these chaperones that can help guide strategies for using chaperones as targets for therapy in protein folding disorders.

生物体编码多个HSP70，以增加根据需要调节HSP70丰度的能力，并提供一系列不同的HSP70功能，以在细胞内执行许多不同的任务。我们构建了一个酵母系统，以评估任何来源的HSP70，发现所有功能冗余的酵母HSP70都具有不同的活性。我们正在继续使用该系统来研究物种内部和整个物种内部的HSP70如何影响体内淀粉样蛋白的传播并在细胞蛋白质质量控​​制（PQC）过程中作用。王室对HSP70及其共伴侣的改变的广泛反应提供了一种敏感的方法，可以研究高度冗余HSP70之间的微妙功能区别，并是一种揭示基本机制的方法。 HSP70通过结合和释放客户端底物蛋白和副酮与HSP70相互作用以调节其活性来起作用。在HSP70反应周期的不同步骤上作用的大量伴侣可以合作，同时提供HSP70活性的广泛功能和微调，以指定其在细胞中定义的作用中的适当功能。 HSP70结合客户蛋白后，核苷酸交换因子（NEF）促进了底物的释放并重新启动结合周期。 我们工作的一个方面着重于确定HSP70的功能是如何通过与NEF合作的方式介导的。在追求几乎相同的HSP70S SSA1和SSA2的不同功能可能是由于与NEF的不同相互作用引起的，我们发现了HSP70 NEF在糖原性酶降解和细胞壁完整性降解中的意外HSP70独立的作用。这些发现提高了人们对这种保守NEF在酵母和可能其他真核细胞中的作用的新认识。 HSP70的变化丰度或功能可以在蛋白质折叠障碍模型中适度病理学，而在相同的模型中，降低伴侣活性的模型会加剧，甚至仅引起病理。因此，HSP70是淀粉样蛋白和其他蛋白质折叠障碍的有前途的治疗候选者，并且正在对其作为药物靶标进行大量评估。改变HSP70的伴侣还可以调节多种淀粉样蛋白和其他蛋白质折叠障碍模型中的病理学。我们为理解功能冗余HSP70活动的特异性的基础的工作可以帮助指导决定哪些HSP70户主成员对此类应用最有用，或者由于不同的HSP70对特定化合物的反应不同，可能会出现的潜在问题。总体而言，我们的工作提供了对这些伴侣的功能的见解，这些功能可以帮助指导使用伴侣作为蛋白质折叠障碍治疗目标的策略。