Regulation of mitosis by proteolysis in yeast

 描述(申请人提供)：非整倍体被定义为染色体数目的改变，而不是单倍体互补的倍数。这种核型变化与人类疾病有关。非整倍体是人类流产和智力低下的主要原因。它也是癌症的一个标志：超过90%的人类实体肿瘤是非整倍体。为了阐明非整倍体与癌症之间的关系，我们必须了解非整倍体是如何影响正常细胞的生理的。我们已经开发了几种酵母和小鼠非整倍体的细胞模型来解决这个问题。我们在酵母中的研究揭示了许多不同的非整倍体共有的一组表型，我们称之为非整倍体相关压力。它们包括转录应激反应、细胞增殖缺陷、能量需求增加、基因组不稳定和蛋白毒性应激。重要的是，我们在哺乳动物细胞中的研究表明，这些与非整倍体相关的压力在真核生物中是保守的。这一发现表明，我们对酵母的研究将为非整倍体条件如何影响哺乳动物细胞生理学和肿瘤发生提供关键的见解。在这里，我们建议研究两种与非整倍体相关的表型，并研究它们是如何联系在一起的。我们将确定非整倍体诱导蛋白毒性的分子基础，以及它如何导致非整倍体细胞的增殖缺陷。此外，我们还将探索非整倍体与衰老之间存在联系的令人兴奋的可能性。在特定的目标1中，我们将确定非整倍体引起的蛋白质组失衡如何导致蛋白毒性应激。具体地说，我们将区分蛋白质质量控制通路在非整倍体细胞中有缺陷或不堪重负的可能性。在特定的目标2中，我们将确定蛋白毒性应激如何影响细胞增殖，特别是在许多不同的非整倍体酵母菌株中发现受损的G1-S相变。最后，在具体目标3中，我们将调查非整倍体是否是衰老的原因。我们的初步数据提出了这一令人兴奋的可能性。我们现在将确定非整倍体是否随着复制年龄的增加而增加，以及特定的非整倍体是否导致了衰老的表型。癌症是高度非整倍体的，承受着巨大的蛋白毒性压力。因此，确定在核型改变的细胞中哪些蛋白质质量控制通路是脆弱的，对于理解癌细胞的生理状态是高度相关的。鉴于衰老的细胞表型在真核生物中是保守的，我们对非整倍体和衰老之间的关系的研究可能对人类的细胞衰老也有重要的意义。

 DESCRIPTION (provided by applicant): Aneuploidy is defined as an alteration in chromosome number that is not a multiple of the haploid complement. Such karyotypic changes are associated with human disease. Aneuploidy is the leading cause of miscarriages and mental retardation in humans. It is also a hallmark of cancer: more than 90% of all solid human tumors are aneuploid. In order to shed light on the relationship between aneuploidy and cancer we must understand how aneuploidy affects the physiology of normal cells. We have developed several cell models of aneuploidy in yeast and mouse to address this question. Our studies in yeast revealed a set of phenotypes shared among many different aneuploidies, which we call the aneuploidy-associated stresses. They include a transcriptional stress response, a cell proliferation defect, increased need for energy, genome instability and proteotoxic stress. Importantly, our studies in mammalian cells revealed that these aneuploidy-associated stresses are conserved across eukaryotes. This discovery indicates that our studies in yeast will provide critical insights into how the aneuploid condition affects mammalian cell physiology and tumorigenesis. Here we propose to study two aneuploidy-associated phenotypes and to investigate how they are connected. We will determine the molecular basis for aneuploidy-induced proteotoxicity and how it contributes to the proliferation defects of aneuploid cells. In addition, we will explore the exciting possibility of a link between aneuploidy and aging. In Specific Aim 1 we will determine how proteomic imbalances caused by aneuploidy lead to proteotoxic stress. Specifically, we will distinguish between the possibilities that protein qualit control pathways are defective or overwhelmed in aneuploid cells. In Specific Aim 2 we will determine how proteotoxic stress impacts cell proliferation, especially the G1 - S phase transition that is found to be impaired in many different aneuploid yeast strains. Finally, in Specific Aim 3 we will investigate whether aneuploidy is a cause of aging. Our preliminary data raise this exciting possibility. We will now determine whether aneuploidy increases with replicative age and whether specific aneuploidies cause the phenotypes that are so characteristic of aging. Cancers are highly aneuploid and under profound proteotoxic stress. Determining which protein quality control pathways are vulnerable in cells with an altered karyotype is thus highly relevant to understanding the physiological state of cancer cells. Given that the cellular phenotypes of aging are conserved across eukaryotes our investigation of the relationship between aneuploidy and aging is likely to also have important implications for cellular aging in humans.