Rat embryonic stem cells (rESCs) are capable of contributing to all differentiated tissues, including the germ line in chimeric animals, and represent a unique, authentic alternative to mouse embryonic stem cells for studying stem cell pluripotency and self-renewal. Here, we describe an EGFP reporter transgene that tracks expression of the benchmark naive pluripotency marker gene Rex1 (Zfp42) in the rat. Insertion of the EGFP reporter gene downstream of the Rex1 promoter disrupted Rex1 expression, but REX1-deficient rESCs and rats were viable and apparently normal, validating this targeted knockin transgene as a neutral reporter. The Rex1-EGFP gene responded to self-renewal/differentiation factors and validated the critical role of β-catenin/LEF1 signaling. The stem cell reporter also allowed the identification of functionally distinct sub-populations of cells within rESC cultures, thus demonstrating its utility in discriminating between cell states in rat stem cell cultures, as well as providing a tool for tracking Rex1 expression in the rat.

大鼠胚胎干细胞（rESCs）能够促进所有分化的组织，包括嵌合动物的生殖系，并代表小鼠胚胎干细胞的独特，可靠的替代品，用于研究干细胞的多能性和自我更新。在这里，我们描述了一个EGFP记者转基因，该基因追踪了大鼠中基准天真多能性标记基因Rex1（Zfp42）的表达。在Rex1启动子下游插入EGFP报告基因会破坏Rex1表达，但缺乏REX1的rESC和大鼠是有活力的，并且显然是正常的，从而验证了这种靶向敲入转基因基因是否为中性报告基因。该REX1-EGFP基因对自我更新/分化因子有反应，并证实了β-catenin/ LEF1信号传导的关键作用。干细胞报告基因还允许鉴定rESC培养物中细胞功能上不同的亚群，从而证明了其在区分大鼠干细胞培养物中细胞状态方面的效用，并提供了追踪大鼠Rex1表达的工具。