Direct generation of complex genetically-modified mouse models via embryonic stem cells

项目摘要：转基因(GM)动物是 研究基础生物学和人类疾病。转基因动物的生产 依赖于两项关键技术：1)稳定的遗传修饰和2)种系 将突变传输到模型系统中。创建的典型方法 复杂的转基因小鼠涉及从正常小鼠产生四亲嵌合体 胚胎和转基因胚胎干细胞，随后进行多轮育种以 同时获得雄性和雌性小鼠用于生殖系繁殖。两个局限性占主导地位 这种方法。首先，多能性的维持限制了基因的复杂性 操纵。第二，这个过程耗时、费力、成本高， 特别是当最终目标需要许多独立的生殖系操作时 同样的动物。我们提出了一个可行的战略，以加快生产 复杂的转基因小鼠模型。利用性逆转技术通过 CRISPR/Cas9介导的男性ES细胞Y染色体缺失和我们新发现的ES 在细胞培养系统中，我们可以直接从 通过四倍体互补(4N)获得相同靶向的ES细胞。这一战略将 绕过至少两代小鼠繁殖：嵌合体发育步骤和 复杂的繁育过程。我们将以男性(XY)ES细胞系为目标 遗传改变和伴随Y染色体缺失产生单体XO 女性胚胎干细胞。使用这一策略，复合纯合转基因小鼠品系可以 以无与伦比的速度和成本建立。在此R21应用程序中，我们建议 以下两个目标：目标1：优化基于AX的ES细胞培养系统 转基因小鼠模型。目的2.直接产生等基因的雄性和雌性复合体 转基因小鼠使用新型ES细胞培养液。如果成功，我们的方法将有一个 在通用性、速度和成本方面都对转基因小鼠模型的构建产生了很大的影响。 这一雄心勃勃的努力是开发一项突破性的技术来创造复杂的 转基因小鼠模型也可能培育新的研究机会。

PROJECT SUMMARY: Genetically modified (GM) animals are essential tools for the study of both fundamental biology and human diseases. The production of GM animals relies on two critical technologies: 1) stable genetic modifications and 2) germline transmission of the mutations into a model system. A typical approach for creation of complex GM mice involves the generation of tetra-parental chimeras from normal embryos and GM embryonic stem (ES) cells, followed by multiple rounds of breeding to obtain both male and female mice for germline propagation. Two limitations dominate this approach. First, maintenance of pluripotency limits the complexity of genetic manipulations. Second, this process is time-consuming, laborious, and costly, particularly if the final objective requires many independent germline manipulations in the same animal. We propose a feasible strategy to accelerate the production of complex GM mouse models. Employing the technology of sex-reversion via CRISPR/Cas9-meditated Y chromosome deletion in male ES cells and our novel ES cell culture system, we can directly generate isogenic male and female mice from the same targeted ES cells through tetraploid complementation (4n). This strategy would bypass at least two mouse breeding generations: the chimera development step and the complex breeding process. We will target male (XY) ES cell lines for intended genetic alterations and follow the deletion of Y chromosome to generate monosomic XO female ES cells. Using this strategy, compound homozygous GM mouse strains could be established at unparalleled speed and costs. In this R21 application we propose the following two Aims: Aim 1: Optimize AX-based ES cell culture system for the production of GM mouse models. Aim 2. Direct generation of isogenic male and female complex GM mice using novel ES cell culture medium. If successful, our approach would have a great impact on GM mouse model construction in terms of versatility, speed, and cost. This ambitious endeavor to develop a breakthrough technology for creation of complex GM mouse models would also possibly foster novel research opportunities.