Safeguards of the Proteome: Elucidating the Roles of Protein Disaggregases

摘要： 蛋白质的正确折叠对所有生命都是必不可少的，这使得异常的蛋白质折叠成为严重的问题。的 蛋白质稳态（proteostasis）网络是一个严格调控的系统，确保蛋白质折叠 并根据需要进行降级。然而，错误折叠的蛋白质可以压倒蛋白质稳态网络。蛋白 错误折叠与许多破坏性的神经变性和心血管疾病有关。蛋白 解聚气体可以接合错误折叠的基质并展开它们，促进它们返回到正确的折叠， 功能分解气体可能作为防止蛋白质稳态网络崩溃的最终防御。 解聚素在维持细胞健康方面起着关键作用，甚至可以调节有益的淀粉样蛋白， 酵母淀粉样蛋白是一种异常稳定的蛋白质构象，与许多人类疾病有关， 而淀粉样蛋白被认为是难以处理的。我假设解聚气体在 维持细胞健康，但当蛋白质稳态网络变得不堪重负时， 疾病因此，调节解聚酶活性的技术可能在治疗上有用。然而，在这方面， 蛋白质解聚是蛋白质稳态网络中最不好表征的分支。我设想建造一个 一项研究计划，重点是更全面地了解分解气体如何对抗 无论是在健康还是在压力下。我试图阐明细胞如何维持蛋白质稳态， 蛋白质稳定作用失败，以及蛋白质分解如何最终应用于预防甚至逆转 蛋白质稳态崩溃。为了进一步实现这些目标，我们将在今后五年内重点关注三个主题： (1)我们将开发和应用新技术来研究和调节Hsp104的底物特异性， 其调节酵母中有益的淀粉样蛋白构象。(2)我们将描述新发现的人类 淀粉样蛋白解聚酶，以更好地了解它们在维持细胞健康中的正常作用，以及它们如何 可能会在疾病中失败。(3)我们将应用新的质谱技术来研究蛋白质重塑 因素选择特定的目标底物，以及这在压力条件下如何变化。我们的工作将阐明 分解气体如何靶向特定底物。此外，这些微调的解聚剂可用作 探针来测试错误折叠的物种是有毒的假设， 折叠和功能可以逆转疾病表型。最终，我们的目标是应用这些研究的发现， 开发治疗神经退行性疾病的新策略。这一点尤为重要，因为尽管 尽管付出了巨大的努力，但仍没有可用于治疗蛋白质错误折叠病症的治疗剂。

Abstract: The proper folding of proteins is essential for all life, making aberrant protein folding severely problematic. The protein homeostasis (proteostasis) network is a tightly regulated system that ensures that proteins are folded and degraded as necessary. However, misfolded proteins can overwhelm the proteostasis network. Protein misfolding is associated with numerous devastating neurodegenerative and cardiovascular disorders. Protein disaggregases can engage misfolded substrates and unfold them, promoting their return to proper fold and function. Disaggregases may serve as the final defense against collapse of the proteostasis network. Disaggregases play key roles in maintaining cellular health, and can even regulate beneficial amyloids in yeast. Amyloid is an exceptionally stable protein conformation that is implicated in numerous human diseases, and amyloid is considered to be otherwise intractable. I hypothesize that disaggregases play key roles in maintaining cellular health, but are vulnerable when the proteostasis network becomes overwhelmed in disease. Therefore, technologies that modulate disaggregase activity might be therapeutically useful. However, protein disaggregases are the least well characterized branch of the proteostasis network. I envision building a research program focused on developing a more comprehensive understanding of how disaggregases counter misfolding, both in health and under stress. I seek to elucidate how cells maintain proteostasis, how proteostasis fails, and how protein disaggregases might ultimately be applied to prevent or even reverse collapse of proteostasis. To further these goals, we will focus on three main themes over the next five years: (1) we will develop and apply new technologies to study and modulate the substrate-specificity of Hsp104, which regulates beneficial amyloid conformers in yeast. (2) We will characterize newly identified human amyloid disaggregases to better understand their normal roles in maintaining cellular health and how they might fail in disease. (3) We will apply new mass spectrometry techniques to study how protein-remodeling factors select specific substrates to target and how this varies under stress conditions. Our work will elucidate how disaggregases target specific substrates. Additionally, these finely-tuned disaggregases can be used as probes to test the hypothesis that misfolded species are toxic, and that restoration of proteins to their native folds and functions can reverse disease phenotypes. Ultimately we aim to apply the findings from these studies to develop new strategies to treat neurodegenerative disease. This is especially important because, despite intense efforts, there are no therapeutics available to treat protein-misfolding disorders.