Assessing L1 retrotransposition events in human iPSCs through deep sequencing.. L1 retrotransposition in human iPSCs

Long interspersed element-1 (LINE-1 or L1) retrotransposition induces insertional mutations that can result in diseases. The recent development of the induced pluripotent stem cells (iPSCs) technology has opened new possibilities for stem cell research. Given the potential of human iPSCs in therapeutic applications also, it is important to verify whether these cells harbor somatic insertions resulting from endogenous L1 retrotransposition. To detect potential somatic insertions in iPSCs caused by retotranspositions of L1Hs (the most active L1 subfamily in the human genome), we used a novel sequencing strategy. As opposed to conventional sequencing direction, we sequenced from the 3’ end of L1Hs to the genomic DNA, thus enabling the direct detection of the polyA tail signature of retrotransposition for verification of true insertions. Targeted L1Hs deep sequencing was thus performed on the parental cells as well as the corresponding iPSC clones.

长散在核元件-1（Long interspersed element-1，LINE-1或L1）的逆转座可引发插入突变，进而导致疾病。近年来，诱导多能干细胞（induced pluripotent stem cells，iPSCs）技术的发展为干细胞研究开辟了全新路径。鉴于人类诱导多能干细胞在治疗应用领域的潜在价值，验证此类细胞是否存在由内源性L1逆转座产生的体细胞插入事件至关重要。为检测由L1Hs（人类基因组中活性最强的L1亚家族）逆转座所引发的iPSCs潜在体细胞插入事件，本研究采用了一种新型测序策略。与传统测序方向不同，我们从L1Hs的3'端向基因组DNA方向进行测序，由此可直接检测到逆转座的polyA尾特征，以验证真实的插入事件。最终，我们对亲本细胞及对应的iPSC克隆株开展了靶向L1Hs深度测序。