Genetic control of mitotic recombination in mice

描述(由申请人提供)：该项目的长期目标是确定RecQ DNA解旋酶调节有丝分裂重组和抑制有丝分裂交叉的作用和机制。 同源重组可以导致交叉，这可能导致易位、缺失和杂合性丢失(LOH)，所有这些都被认为是潜在的致癌或促癌事件。因此，在哺乳动物中，有丝分裂重组受到高度调控，以防止过度交叉。RecQ家族成员BLM的突变会导致Bloom综合征；这种疾病的典型特征是有丝分裂交叉增加和癌症风险增加，强调了RecQ解旋酶在抑制有丝分裂交叉和致癌方面的重要性。此前，我们已经证明，Bloom综合征的小鼠模型由于减少了对有丝分裂交叉的抑制而增加了肿瘤的易感性。我们现在发现，第二个RecQ家族成员，小鼠RecqlS，也参与了有丝分裂交叉的抑制，并且它在这种抑制中与BLM在遗传上相互作用。我们假设，在哺乳动物中，复制死亡是自发有丝分裂交叉的主要原因。两条独立的通路：BLM特异性通路和RecqlS特异性通路，分别负责通过基于非重组的机制恢复停滞的分叉，以抑制有丝分裂交叉和降低癌症风险。在这个应用中，我们建议使用我们创建的基因敲除小鼠细胞系和基因敲除小鼠模型来检验这一假说，并研究这两个提出的途径在抑制有丝分裂交叉和致癌方面的相对贡献。这些研究将为有丝分裂重组的调控和癌变过程中早期致癌LOH事件的起源提供重要的见解。

DESCRIPTION (provided by applicant): The long-term objective of this project is to define the roles and mechanisms by which the RecQ DNA helicases regulate mitotic recombination and suppress mitotic crossover. Homologous recombination can lead to crossover, which can lead to translocations, deletions, and loss of heterozygosity (LOH), all of which have been implicated as potential cancer causing or - promoting events. Thus, in mammals, mitotic recombination is highly regulated to prevent excessive crossover. Mutations in the RecQ family member BLM give rise to Bloom syndrome; a disease typified by increased mitotic crossovers and elevated risks to cancer, underscoring the importance of RecQ helicases in the suppression of mitotic crossover and carcinogenesis. Previously, we have shown that a mouse model of Bloom syndrome has increased tumor susceptibility as a result of diminished suppression of mitotic crossover. We have now found that a second RecQ family member, mouse RecqlS, is also involved in the suppression of mitotic crossover, and that it interacts genetically with Blm in this suppression. We hypothesize that in mammals, replication demise is the primary cause of spontaneous mitotic crossover. Two independent pathways: a Blm-specific pathway and a RecqlS-specific pathway, respectively, are responsible for the restoration of stalled forks via non-recombination-based mechanism to suppress mitotic crossover and reduce cancer risk. In this application, we propose to use the knockout mouse cell lines and knockout mouse models we have created to test this hypothesis and to study the relative contributions of these two proposed pathways in the suppression of mitotic crossover and carcinogenesis. These studies will provide significant insights into the regulation of mitotic recombination and the origins of the early oncogenic LOH events during carcinogenesis.