Centrosomes and BRCA1

BRCA1基因突变导致乳腺癌和卵巢癌的原因尚不清楚。最近的数据来自这个 实验室表明，BRCA1肿瘤抑制因子的泛素化活性调节复制 以及中心体在组织培养中特定于乳腺上皮细胞的功能。使用瞬时化验 为了抑制BRCA1的功能，我们还没有观察到中心体扩增来自非 乳房组织。在最早和最具侵袭性的乳房中观察到中心体放大 BRCA1的这种功能可能在这些肿瘤的病因学中起关键作用。我们的数据 揭示了一种新的生物途径，它控制中心体的数量和功能，并依赖于 BRCA1在乳腺细胞中的功能。本项目将通过三个目标来剖析BRCA1的功能。1) 从乳腺细胞纯化的中心体中鉴定BRCA1泛素化的多肽靶点 台词。通过BRCA1依赖的泛素化活性修饰的蛋白质将被检测对 中心体复制。2.)BRCA1依赖泛素化对中心体微管的影响 将在体外和体内检测成核功能，并检测蛋白质和泛素化底物 在目标1中确定的也将被测试以调节BRCA1在该细胞器上的功能。3.)我们会 确定非乳腺细胞中使BRCA1泛素化活性多余的因素，并进行测试 新发现的因子加BRCA1是否调节这些细胞类型中的中心体放大。这 该项目将确定BRCA1调节中心体复制和中心体的机制 在乳房细胞中发挥作用。 早期乳腺癌细胞最早的变化之一是细胞机器的问题。 当乳腺细胞分裂时，这会分离DNA。这个实验室的研究发现， 这种机器的功能被称为中心体，在乳腺细胞中由BRCA1蛋白控制。这 项目将剖析中心体的工作原理，并确定BRCA1如何在正常情况下控制其功能 细胞，我们将了解当BRCA1功能因突变而丢失时，这一过程是如何改变的，就像在 乳腺癌。

Why mutations in the BRCA1 gene result in breast and ovarian cancer is unknown. Recent data from this laboratory suggest that the ubiquitination activity of the BRCA1 tumor suppressor regulates the duplication and function of centrosomes specifically in mammary epithelial cells in tissue culture. Using a transient assay to inhibit BRCA1 function, we have not observed centrosome amplification in cell lines derived from non- breast tissue. Centrosome amplification has been observed in the earliest and most aggressive breast cancer lesions, and it is likely that this function of BRCA1 is critical in the etiology of these tumors. Our data has revealed a new biological pathway, which controls centrosome number and function and which depends on the function of BRCA1 in breast cells. This project will dissect the BRCA1 function via three aims. 1.) Polypeptide targets of BRCA1 ubiquitination will be identified from centrosomes purified from breast cell lines. Proteins modified by the BRCA1-dependent ubiquitination activity will be assayed for effects on centrosome duplication. 2.) The effects of BRCA1-dependent ubiquitination on centrosome microtubule nucleation function will be assayed in vitro and in vivo, and the proteins and ubiquitinated substrates identified in aim 1 will also be tested for modulating the function of BRCA1 on this organelle. 3.) We will identify the factors in non-breast cells which render the BRCA1 ubiquitination activity redundant, and test whether the newly identified factor plus BRCA1 regulate centrosome amplification in these cell types. This project will identify the mechanism by which BRCA1 regulates centrosome duplication and centrosome function in breast cells. One of the earliest changes in the cells in an incipient breast cancer is a problem with the cellular machine that segregates the DNA when the breast cell divides. Research in this laboratory has found that the function of this machine, called a centrosome, is controlled in breast cells by the BRCA1 protein. This project will dissect the workings of the centrosome and determine how BRCA1 controls its function in normal cells, and we will learn how this process is changed when BRCA1 function is lost by mutation as happens in breast cancer.