Chaperone-amyloid interactions

伴侣-淀粉样蛋白相互作用

• 批准号: 9356059
• 负责人: Daniel Masison
• 金额: $ 32.52万
• 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/9356059
• 关键词: Affect; Amyloid; Biochemical; Cell physiology; Cells; Cytoplasm; Disease; Family; Genetic; Glutamine; Goals; Growth; Human; Huntington gene; In Vitro; Mediating; Methods; Molecular; Molecular Chaperones; Mutation; Phenotype; Prions; Property; Protein Structure Initiative; Proteins; Quality Control; Resistance; Role; Site; Structure; System; Toxic effect; Variant; Work; Yeasts; amyloid structure; base; falls; fibrous protein; in vivo; interest; mutant; protein aggregate; protein misfolding; sup35; yeast prion; yeast protein

One ongoing study focuses on how alterations in structures of prion proteins can affect prion phenotypes, possibly related to effects on chaperone interactions. As an approach to identify sites on prion proteins that might interact with chaperones, we have been isolating mutants of prion proteins that have alterations outside the amyloid-forming region that interfere with ability of the proteins to propagate as stable prions. They fall into two major classes, those that interfere with propagation of endogenous prions formed of wild type proteins and those that don't. We are using genetic and biochemical methods to determine if the observed effects on prion phenotype are due to differences in how the prion proteins self-associate or interact with various chaperones. Our preliminary work suggests that some mutations can influence the ability of the proteins to form amyloid, while others affect interactions with chaperones, that in turn affect how efficiently the prions propagate. Sis1 is a major yeast J-protein of the Hsp40 family that is essential for growth and has important roles in prion propagation. Our earlier work implicates Sis1 as possessing a function that protects cells from lethal effects of PSI prions and we are investigating the basis of this toxicity. Preliminary findings point to a specific chaperone activity that becomes necessary when the prions are present, rather than a specific cellular process that is being perturbed by defective chaperone function. Continued work aims to identify this activity and the mechanisms of how it provides protection. Expressing huntingtin fragments with disease-associated expansion of glutamines (HttQ103) is toxic in yeast containing either the PIN prion, which is an amyloid form of Rnq1, or PSI prion, which is an amyloid form of Sup35. In an effort to understand this toxicity we are examining in detail the effects of expressing various Htt fragments in cells propagating different prion variants. The human J-protein DnaJB6 has potent anti-amyloid activity on several different mammalian proteins that have propensity to form amyloid, and it protects cells from toxic effects of expressing HttQ103. We showed DnaJB6 also protects yeast from HttQ103 toxicity, but by affecting HttQ103 aggregation in a different way. We also found that DnaJB6 cures yeast of URE3 prions and weak, but not strong versions of PSI prions. We found the amyloid structures of the curable prions composed of different proteins were more related than those of the differentially sensitive prions composed of the same protein. These findings showed that DnaJB6 anti-amyloid activity extends to yeast proteins. They also defined different structural variants of amyloid, even when formed by the same protein, that are differentially sensitive to this activity. These findings have important implications for the growing attraction to DnaJB6 as a potential therapy for amyloid disorders, especially because prions with the resistant structures of amyloid are more highly infectious.

一项正在进行的研究集中于prion蛋白结构的变化如何影响幼虫表型，这可能与对伴侣相互作用的影响有关。作为鉴定可能与伴侣伴侣相互作用的prion蛋白的位点的方法，我们一直在隔离蛋白质蛋白的突变体，这些突变体在淀粉样蛋白形成区域之外具有变化的蛋白质，这些蛋白质会干扰蛋白质作为稳定prions的能力。它们属于两个主要类别，这些类别干扰由野生型蛋白质和不传播的内源性prions的传播。我们使用遗传和生化方法来确定观察到的对prion表型的影响是否是由于prion蛋白如何自我缔合或与各种伴侣相互作用的差异。我们的初步工作表明，某些突变会影响蛋白质形成淀粉样蛋白的能力，而另一些突变会影响与伴侣的相互作用，这反过来又影响了prions的传播效率。 SIS1是HSP40家族的主要酵母J蛋白，对生长至关重要，并且在prion传播中具有重要作用。我们较早的工作暗示SIS1具有保护细胞免受PSI Prions致命作用的功能，我们正在研究这种毒性的基础。初步发现指出了特定的伴侣活性，该活动是在存在prions时必不可少的，而不是特定的细胞过程，该过程受到缺陷的伴侣功能扰动的特定细胞过程。持续的工作旨在确定这项活动以及如何提供保护的机制。 表达具有疾病相关的谷氨酰胺扩张（HTTQ103）的狩猎蛋白片段在含有PIN prion的酵母中有毒，这是RNQ1的一种淀粉样蛋白形式，或PSI Prion，这是SUP35的淀粉样蛋白形式。为了了解这种毒性，我们正在详细研究表达各种HTT片段在传播不同prion变体的细胞中的影响。人类J蛋白DNAJB6对几种具有形成淀粉样蛋白倾向的几种不同哺乳动物蛋白具有有效的抗淀粉样活性，并且可以保护细胞免受表达HTTQ103的毒性作用。我们显示DNAJB6还保护酵母免受HTTQ103毒性的影响，但通过以不同的方式影响HTTQ103的聚集。 我们还发现，DNAJB6治愈URE3 Prions的酵母和弱的PSI Prions版本。我们发现，由不同蛋白质组成的可固化的蛋白质的淀粉样蛋白结构比由相同蛋白质组成的差异敏感的prions的淀粉样蛋白更相关。这些发现表明DNAJB6抗淀粉样活性延伸至酵母蛋白。他们还定义了淀粉样蛋白的不同结构变体，即使是由同一蛋白质形成的，这些变体对此活性有差异敏感。这些发现对DNAJB6的吸引力的吸引力越来越重要，作为淀粉样蛋白疾病的潜在疗法，尤其是因为具有淀粉样蛋白耐药性结构的prions具有更高的感染性。