Genetic Modifiers of Genome Instability & Cancer in Mice

最近产生了一种WRN“基因敲除”小鼠(WRN Delta)，它消除了WRN蛋白的表达(类似于Werner综合征)，但不能传递显著的表型。这表明小鼠的功能冗余掩盖了Wrn4的表型。目标是 该项目的目的是表征WRN的潜在遗传修饰物，这些基因修饰物影响WRN三角洲小鼠的基因组不稳定和癌症。具体目标是： 1.确定遗传背景对WRN Delta小鼠肿瘤发生的影响。我们将快速检验这一假设，即遗传背景改变了WRN Delta小鼠的表型。我们的方法是将WRN Delta等位基因引入具有不同固有癌症表型的同源近交系中，对不同自交系中WRN Delta的广泛分析将确定遗传背景和WRN Delta等位基因对组织特异性癌症风险的相对贡献。 2.研究WRN与BLM、ATM和Msh2的功能相互作用。在酵母中的研究表明，平行的冗余路径经常被用来保持基因组的稳定性。这些基因的一个子集需要WRN同源基因SGS1。因此，当sgs1零突变与平行路径上的缺陷相结合时，自发总染色体的协同作用增加。 观察到重排(GCR)。使用现有的基因敲除小鼠品系，我们将检查三个被预测与WRN Delta协同作用的突变体：BLm Delta、ATM Delta和Msh2 Delta。 3.确定DNA聚合酶错误对WRN Delta小鼠的影响。RecQ解旋酶与复制的DNA聚合酶密切相关(SGS1与DNA聚合酶epsilon上位；WRN与DNA聚合酶Delta结合)，并假设自发的GCRs在很大程度上是由DNA复制错误引起的。这表明容易出错的DNA复制会放大WRN增量表型。我们将通过将WRN Delta小鼠与我们实验室最近培育的两个对Pol Delta或Pol epsilon有缺陷的“突变”小鼠品系杂交来测试这一想法。 总之，这些实验将揭示WRN功能相互作用，影响基因组不稳定和小鼠癌症。我们的长期目标是开发一个概括Werner综合征癌症表型基本方面的MEUSE模型，这些研究将与细胞功能-Monnat和重组机制-Maizels项目整合，以开发RIVE中WNR功能的详细分子和组织描述。我们的研究还将为与第一个项目(生物化学-Loeb)合作评估WRN Exo-、Hel-和SNP“敲打”小鼠奠定基础。

A Wrn "knockout" mouse (Wrn delta) was recently generated that eliminates WRN protein expression (similar to Werner Syndrome) but fails to impart a significant phenotype. This suggests that functional redundancies in mice mask the Wrn4 phenotype. The objective of this project is to characterize potential genetic modifiers of Wrn that affect genome instability and cancer in Wrn delta mice. The SPECIFIC AIMS are: 1. Determine the effect of genetic background on cancer development in Wrn delta mice. We will fast test the hypothesis that genetic background modifies the phenotype of Wrn delta mice. Our approach will be to introduce the Wrn delta allele into congenic inbred strains with different inherent cancer phenotypes, An extensive analysis of Wrn delta in different inbred strains will determine the relative contributions of genetic background and the Wrn delta allele to tissue-specific cancer risk. 2. Examine functional interactions of Wrn with Blm, Atm and Msh2. Studies in yeast show that parallel redundant pathways are often employed to preserve genome stability. A subset of these require the WRN homolog, SGS1. Accordingly, when sgs1 null mutations are combined with defects in parallel pathways, synergistic increases in spontaneous gross chromosomal rearrangements (GCRs) are observed. Using available knockout mouse strains, we will examine three mutants that are predicted to synergize with Wrn delta: Blm delta, Atm delta and Msh2 delta. 3. Determine the effect of DNA polymerase errors in Wrn delta mice. RecQ helicases are closely linked to replicative DNA polymerases (SGS1 is epistatic with DNA polymerase epsilon; WRN binds DNA polymerase delta), and it is hypothesized that spontaneous GCRs result, in large part, from DNA replication errors. This suggests that error-prone DNA replication wilt amplify the Wrn delta phenotype. We will test this idea by crossing Wrn delta mice with two "mutator" mouse lines recently generated in our laboratory that are defective for Pol delta or Pol epsilon proofreading. Together, these experiments will reveal Wrn functional interactions that affect genome instability and cancer in mice. Our long-term goal is to develop a meuse model that recapitulates fundamental aspects of the Werner Syndrome cancer phenotype, These studies will be integrated with the Cell Function-Monnat and Recombination Mechanisms-Maizels projects to develop a detailed molecular and organismal description of WNR function in rive. Our studies will also lay the ground work for a collaboration with the first project (Biochemistry-Loeb) evaluating Wrn Exo-, Hel- and SNP "knockin" mice.