Molecular Basis of Aneuploidy

这项建议集中在一个重要但未探索的问题- howsteroid激素， 已知的风险因素，与p53突变相互作用，产生非整倍体和恶性肿瘤，以及如何 与染色体分离蛋白Separase有关？我们的性类固醇依赖性p53小鼠肿瘤前 乳腺癌模型允许一种独特的方法来解决这个问题。在该模型中，p53中的类固醇诱导 突变乳腺导致染色体不稳定性、非整倍性和肿瘤形成， 在大多数人类乳腺癌中都能看到。我们提出了一个范式，有一组蛋白质， 其失调促进非整倍性（称为PRAN;非整倍性启动子），包括 染色体不稳定性，导致整个或部分染色体的丢失或获得， PRAN蛋白受类固醇激素和肿瘤抑制因子p53的交互调节。 我们发表的和新的初步数据提供了第一个证据，表明类固醇激素在 参与姐妹染色单体凝聚和分离的有丝分裂蛋白的调节。我们建议 肿瘤抑制基因p53的突变和类固醇激素信号的联合作用产生了 通过影响参与染色体分离的关键蛋白质的表达，在乳腺癌中产生非整倍体。我们 重点是调控染色体分离的因素，特别是姐妹染色单体 凝聚/分离蛋白，作为候选PRAN蛋白，因为染色体错误分离期间， 有丝分裂可导致非整倍体。在这项分析中的一个关键基因是ESPL 1，它编码一种内肽酶 这种酶通过在染色单体形成过程中切割粘附蛋白Rad 21/SCC 1/MCD 1来分离相连的姐妹染色单体。 中期到后期的过渡假设p53基因敲除小鼠的激素刺激 乳腺导致ESPL 1基因的错误表达，从而促进非整倍体和乳腺癌 阵该建议应用p53突变体和野生型（WT）乳腺细胞的体内移植， 用ESPL 1稳定转染，并建立ESPL 1转基因小鼠模型以测试PRAN范例 激素治疗后。类固醇和p53在转录水平上对ESPL 1的调节通过以下方法进行研究： 表征ESPL 1启动子区域。这些目标将通过以下两项具体工作来实现： 目的：1）Separaseoverexpression在非整倍体中的功能作用，2）ESPL 1的转录调控 基因表达。这项研究不仅阐明了乳腺癌诱导的潜在机制， 非整倍体是癌症生物学中一个基本的未解决的问题，但也可能识别出一类新的非整倍体。 导致染色体不稳定和乳腺癌进展的蛋白质。

This proposal focuses on an important but unexplored problem - howsteroid hormones, which are well known risk factors, interact with p53 mutations to produce aneuploidy and malignancy, and how the chromosomal segregation protein Separase is involved? Our sex-steroid dependent p53-mice preneoplastic breast cancer model allows a unique approach to this problem. In this model, steroidal induction in p53 mutant mammary glands results in chromosomal instability, aneuploidy and tumor formation analogous to that seen in majority of human breast cancers. We propose a paradigm that there is a set of proteins whose deregulation promotes aneuploidy (termed PRAN; Promoter of Aneuploidy) including chromosomal instability which results in loss or gain of whole or parts of chromosomes, and that PRAN proteins are interactively regulated by steroid hormones and the tumor suppressor p53. Our published and new preliminary data provide the first evidence that steroid hormones play a role in the regulation of mitotic proteins involved in sister chromatid cohesion and separation. We propose that the combined effect of mutation of the tumor suppressor p53 and signaling by steroid hormones produces aneuploidv in breast cancer by affecting expression of key proteins involved in chromosomal separation. We focuses on the elements that regulate chromosomal segregation, particularly sister chromatid cohesion/separation proteins, as candidate PRAN proteins, since chromosome missegregation during mitosis can lead to aneuploidy. A key gene in this analysis is ESPL1, which encodes an endopeptidase called Separase that separates joined sister chromatids by cleaving cohesin Rad21/SCC1/MCD1 during the metaphase to anaphase transition. The hypothesis is that hormonal stimulation of p53 null mouse mammary glands results in misexpression of the ESPL1 gene, thus promoting aneuploidy and breast cancer formation. This proposal applies in vivo transplantaion of p53 mutant and wild type (WT)mammary cells that are stably transfeeted with ESPL1, and an ESPL1 transgenic mice model to test the PRAN paradigm following hormone treatment. Steroid and p53 regulation of ESPL1 at the transcriptional level is studied by characterizing the ESPL1 promoter region. These objectives will be accomplished by pursuing two specific aims: 1) Functional role of Separaseoverexpressionin aneuploidy, and 2) Transcriptional regulation of ESPL1 gene expression. The proposed study not only elucidate underlying mechanisms of hormone-induced aneuploidy, a fundamental unresolved question in cancer biology, but also likely to identify a new class of proteins that are responsible for chromosomal instability and breast cancer progression.