Characterizing the LINE-1 Retrotransposition-Replication Conflict

项目摘要 我们的基因组大部分是由源自移动的遗传元件活动的散布重复序列组成的。 这些序列的子集在癌症中被激活。我们的研究实验室和其他实验室 显示几乎一半的癌症不能抑制长散布元件-1（LINE-1，L1）序列。L1是一 编码两种蛋白质的活性反转录转座子，一种RNA结合蛋白（ORF 1 p）和一种 核酸内切酶和逆转录酶活性（ORF 2 p）。奇怪的是，虽然这些蛋白质 在许多人类癌症中普遍表达，它们抑制培养物中的细胞生长。我们有令人振奋的新数据 从全基因组敲除筛选中， 使它们能够存活和生长，尽管它们表达L1。更重要的是，这些屏幕还 确定了在应对L1表达的细胞中必不可少的基因。这些合成的致命基因 代表L1（+）细胞独特的分子脆弱性。L1（+）细胞需要特定的DNA修复途径， 有效的复制应激信号通路和复制叉重启能力。在这里，我们将测试 假设这些途径是消除L1插入中间体和防止碰撞所必需的 这些中间体和DNA复制叉之间的联系这个项目将增加我们对如何 癌细胞复制DNA这为进一步利用L1相关DNA复制应激， 限制癌细胞生长。

Project Summary Much of our genome is made up of interspersed repeats derived from the activities of mobile genetic elements. There are subsets of these sequences that become activated in cancers. Our research lab and others have shown that nearly half of cancers fail to restrain long interspersed element-1 (LINE-1, L1) sequences. L1 is an active retrotransposon that codes for two proteins, an RNA binding protein (ORF1p) and a protein with endonuclease and reverse transcriptase activities (ORF2p). Paradoxically, though these proteins are pervasively expressed in many human cancers, they inhibit cell growth in culture. We have exciting new data from genome-wide knockout screens demonstrating how tumor suppressor gene mutations found in cancers enable them to survive and grow despite their expression of L1. More importantly, these screens have also identified genes that become essential in cells coping with L1 expression. These synthetic lethal genes represent unique molecular vulnerabilities for L1(+) cells. L1(+) cells require specific DNA repair pathways, effective replication stress signaling pathways, and replication fork restart capabilities. Here, we will test the hypothesis that these pathways are required to eliminate L1 insertion intermediates and prevent collisions between these intermediates and DNA replication forks. This project will increase our understanding of how cancer cells replicate their DNA. It could lay a foundation to leverage L1-associated DNA replication stress to limit cancer cell growth.