SISTER CHROMATID COHESION AND THE ORIGIN OF TETRAPLOIDY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 倍性（染色体数目）的不适当维持是许多癌细胞类型的标志，并且被认为有助于癌细胞群体中的恶性。 在许多肿瘤中，四倍体，正好是正常DNA补体的两倍，在更退化的异染色体状态之前，单个染色体似乎随机丢失或获得。 这种情况被称为染色体不稳定性，或“CIN”表型。 最初的四倍体状态是如何发展的尚不清楚。 在之前的资助期间，我们开始了对四倍体细胞中染色体行为的研究。 在这里，我们提出的研究中，我们专门着眼于四倍体的发展。 一些证据强烈表明，脊椎动物中姐妹染色单体凝聚力（SCC）缺陷与非整倍体之间存在直接联系。 在这里，我们提出，染色体不稳定性的发展，在两个步骤中响应的损失凝聚力。 在第一步中，降低的凝聚力导致通过有丝分裂滑移形成四倍体细胞。 在第二步中，四倍体细胞为整个染色体的错误分离提供了一个允许的环境，最终导致染色体不稳定。 在下面的建议中，我们描述了一组实验，我们将测试这个模型的第一部分，即姐妹染色单体凝聚力的失败导致四倍体通过有丝分裂滑移。我们将以两种方式做到这一点。 首先，我们将产生内聚缺陷的细胞或细胞系，并监测这些细胞中四倍体形成的速率。 其次，我们将确定弱化或失活的纺锤体检查点是否加速了具有受损凝聚力的细胞中四倍体的发展。 本提案中描述的实验数据将提供重要的洞察力，以了解内聚失败如何导致染色体不稳定，从而有助于肿瘤的发展和恶性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Improper maintenance of ploidy (chromosome number) is a hallmark of many cancer cell types, and is thought to contribute to malignancy in cancer cell populations. In a number of tumors tetraploidy, exactly twice the normal complement of DNA, precedes a more degenerate aneusomic state in which individual chromosomes appear to be lost or gained at random. This condition is referred to as the chromosome instability, or "CIN" phenotype. How the initial tetraploid state develops is not known. In a prior funding period, we began an investigation of the behavior of chromosomes in tetraploid cells. Here we propose studies in which we look specifically at the development of tetraploidy. Several lines of evidence strongly suggest a direct connection between defective sister chromatid cohesion (SCC) and aneuploidy in vertebrates. Here we propose that chromosome instability develops in two steps in response to loss of cohesion. In the first step, reduced cohesion results in the formation of tetraploid cells through mitotic slippage. In the second step, tetraploid cells provide a permissive environment for the missegregation of whole chromosomes, leading eventually to chromosome instability. In the following proposal we describe a set of experiments with which we will test the first part of this model, that failures in sister chromatid cohesion lead to tetraploidy through mitotic slippage. We will do this in two ways. First, we will generate cells or cell lines defective in cohesion and monitor the rate of tetraploid formation in these cells. Secondly, we will determine whether a weakened or inactivated spindle checkpoint accelerates the development of tetraploidy in cells with compromised cohesion. The data from the experiments described in this proposal will provide important insight into how failures in cohesion might lead to chromosome instability, and thus contribute to tumor development and malignancy.