Regulation of Mitosis by Proteolysis in Yeast

描述（由申请人提供）：非整倍体是癌症的标志，也是人类流产的主要原因。因此，确定非整倍体的原因和后果对于理解肿瘤形成和不育的基本原理至关重要。我们研究的长期目标是确定防止染色体错误分离的机制，从而防止非整倍性和非整倍性在分子水平上对细胞增殖的影响。本提案的三个具体目标旨在解决这两个问题。在具体目标1中，我们使用分子和生物化学方法来确定有丝分裂退出网络（一种促进有丝分裂退出所必需的调节网络）是如何调节的。特别是，我们将确定，如何控制这一途径的GTP酶，并使用这些信息，开发体内的GTP酶活性的读出。在具体目标2中，我们将研究被称为纺锤体位置检查点的监视机制如何影响MEN活性。具体地说，我们将确定纺锤体位置检查点组分Kin4如何调节MEN，并检验酵母细胞在MEN抑制区（母细胞）和MEN激活区（芽）中的分裂是在酵母中感知纺锤体位置的机制的假设。在具体目标3将描述非整倍体的后果。我们已经发现，许多酵母菌株与一个或两个额外的染色体在G1延迟。我们将确定此G1延迟的原因。此外，我们将通过鉴定功能丧失等位基因和缩短非整倍体G1期延迟的高拷贝质粒来鉴定介导G1期延迟的基因。他们的分析将揭示非整倍体如何延迟细胞周期进程。

DESCRIPTION (provided by applicant): Aneuploidy is a hallmark of cancer and the leading cause of miscarriages in humans. Determining the causes and consequences of aneuploidy is thus vital for understanding the principles underlying tumor formation and infertility. The long-term goal of our studies is to define the mechanisms that prevent chromosome mis-segregation and thus aneuploidy and the consequences of aneuploidy on cell proliferation at the molecular level. The three Specific Aims of this proposal are aimed at addressing these two questions. In Specific Aim 1, we use molecular and biochemical approaches to determine how the Mitotic Exit Network, a regulatory network essential for promoting exit from mitosis, is regulated. In particular, we will determine, how the GTPase of this pathway is controlled and, using this information, develop in vivo read outs for the activity of the GTPase. In Specific Aim 2 we will investigate how a surveillance mechanism known as the spindle position checkpoint affects MEN activity. Specifically, we will determine how the spindle position checkpoint component Kin4 regulates the MEN and test the hypothesis that division of the yeast cell in a MEN inhibitory zone (the mother cell) and a MEN activating zone (the bud) is the mechanism whereby spindle position is sensed in yeast. In Specific Aim 3 will characterize the consequences of aneuploidy. We have discovered that many yeast strains with one or two extra chromosomes are delayed in G1. We will determine the cause(s) of this G1 delay. Furthermore we will identify genes that mediate this G1 delay by identifying loss of function alleles and high copy plasmids that shorten the G1 delay in aneuploids. Their analysis will shed light on how aneuploidy delays cell cycle progression.