Cellular Mechanisms of Aggregation of Abnormal Proteins

描述（由申请人提供）：泛素蛋白酶体机制和分子伴侣的失效可能导致突变或受损多肽的聚集，从而导致各种破坏性疾病。然而，特殊的分子机制已经发展成为最后一道防线，通过将错误折叠的蛋白质聚集体/寡聚体转运到中心体定位的攻击体来减轻蛋白毒性。该建议的主要目的是揭示侵略形成的机制。所提出的工作是基于我们的酵母模型的蛋白质与扩展的聚谷氨酰胺（polyQ）结构域的聚集。在过去，该模型被用于在HD小鼠模型中鉴定抑制polyQ聚集、改善运动性能和减少神经元萎缩的小分子。利用该模型，我们已经确定（a）酵母和哺乳动物细胞中的攻击基因组形成需要底物蛋白上的可转移的攻击基因组靶向信号，例如富含脯氨酸的区域（B）SH 3结构域蛋白Boi 2用作P区攻击基因组靶向信号的识别元件，（c）酵母14 - 3 - 3蛋白Bmh 1和Cdc48/VCP-Ufd 1-Nlp4复合物的组分在侵袭基因组形成中起重要作用。我们还建立了一个细胞培养模型的侵略形成调查的相关性为哺乳动物细胞的侵略组件中鉴定的酵母。在目标1中，我们将阐明攻击组机制如何识别小的polyQ聚集体/寡聚体。我们将建立SH3结构域蛋白Boi2在酵母中识别聚集体的作用，并将澄清Boi2同系物在哺乳动物细胞中是否具有识别亨廷顿蛋白和其他含polyQ的病理蛋白的功能。在目标2中，我们将确定14 - 3 - 3蛋白Bmh 1在酵母中侵袭基因组形成的早期阶段的功能，并将测试14 - 3 - 3蛋白是否在哺乳动物细胞中侵袭基因组形成中发挥一般作用。这些实验将有助于阐明攻击组机制如何区分异常多肽的小聚集体/寡聚体与可溶性单体。在目标3中，使用生物化学和遗传方法，我们将鉴定出参与攻击体形成的新组分。作为这项工作的结果，我们计划获得足够的信息，了解侵略形成的机制。许多破坏性疾病，包括主要的神经退行性疾病，都是由异常蛋白质的积累引起的。这些异常的种类倾向于聚集，在这里，我们将建立蛋白质聚集的细胞机制。这项工作将揭示生物体如何试图保护自己免受亨廷顿病和某些其他疾病的发展。

DESCRIPTION (provided by applicant): Failure of the ubiquitin proteasome machinery and molecular chaperones may result in aggregation of mutant or damaged polypeptides leading to various devastating diseases. However, special molecular machinery has evolved as a last line of defense to relieve proteotoxicity by transporting misfolded protein aggregates/oligomers to the centrosome-localized aggresome. The main objective of this proposal is to uncover the mechanisms of aggresome formation. The proposed work is based on our yeast model of aggregation of proteins with expanded polyglutamine (polyQ) domains. In the past, this model was used to identify small molecules that suppress polyQ aggregation, improve motor performance and reduce neuronal atrophy in a mouse model of HD. With this model, we have established that (a) aggresome formation both in yeast and mammalian cells requires transferable aggresome-targeting signals on substrate proteins, e.g. the proline-rich region (P-region) of exon 1 of huntingtin, (b) an SH3-domain protein Boi2 serves as a recognition element for the P-region aggresome- targeting signal, (c) a yeast 14-3-3 protein Bmh1 and components of the Cdc48/VCP-Ufd1-Nlp4 complex play an essential role in aggresome formation. We also established a cell culture model of aggresome formation to investigate the relevance for mammalian cells of aggresome components identified in yeast. In Aim 1 we will clarify how the aggresome machinery recognizes small polyQ aggregates/oligomers. We will establish the role of the SH3-domain protein Boi2 in the recognition of the aggregates in yeast, and will clarify whether Boi2 homologs function in mammalian cells to recognize huntingtin and other polyQ-containing pathological proteins. In Aim 2 we will establish the function of the 14-3-3 protein Bmh1 in early stages of aggresome formation in yeast, and will test whether 14-3-3 proteins play a general role in aggresome formation in mammalian cells. These experiments will help to clarify how the aggresome machinery distinguishes small aggregates/oligomers of abnormal polypeptides from soluble monomers. In Aim 3 using both biochemical and genetic approaches we will identify novel components involved in aggresome formation. As a result of this work, we plan to obtain sufficient information for understanding the mechanism of aggresome formation. PUBLIC HEALTH RELEVANCE Many devastating diseases, including major neurodegenerative disorders, are caused by accumulation of abnormal proteins. These abnormal species tend to aggregate, and here we will establish cellular mechanisms of protein aggregation. This work will uncover how organisms try to protect themselves from development of Hungtington's and certain other diseases.