Li Guo-ling, Zhong Cui-li, Mo Jian-xin, Quan Rong, Wu Zhen-fang, Li Zi-cong, Yang Hua-qiang, Zhang Xian-wei
National Engineering Research Center for Swine Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
1. National Engineering Research Center for Swine Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; 2. Guangdong Wens Foodstuff Co., Ltd., Xinxing 527439, China.
Yi Chuan. 2017 Feb 20;39(2):98-109. doi: 10.16288/j.yczz.16-367.
The traditional transgenic technologies, such as embryo microinjection, transposon-mediated integration, or lentiviral transfection, usually result in random insertions of the foreign DNA into the host genome, which could have various disadvantages in the establishment of transgenic animals. Therefore, a strategy for site-specific integration of a transgene is needed to generate genetically modified animals with accurate and identical genotypes. However, the efficiency for site-specific integration of transgene is very low, which is mainly caused by two issues. The first one is the low efficiency of inducing double-strand break (DSB) at the target site of host genome in the initial process. The second one is the low efficiency of homologous recombination repair (HDR) between the target site and the donor plasmid carrying homologous arm and foreign genes. HDR is the most common mechanism for site-specific integration of a transgene. DSBs can stimulate DNA repair mainly by two competitive mechanisms, HDR and nonhomologous end joining (NHEJ). Hence, activation of HDR or inhibition of NHEJ can promote the HDR in the integration processes, thereby optimizing a specific targeting of the transgene. In this review, we summarize the recent advances in strategies for improving the site-specific integration of foreign transgene in transgenic technologies.
传统的转基因技术，如胚胎显微注射、转座子介导的整合或慢病毒转染，通常会导致外源DNA随机插入宿主基因组，这在转基因动物的构建过程中可能会有各种不利之处。因此，需要一种转基因定点整合策略来培育具有准确且相同基因型的基因编辑动物。然而，转基因定点整合的效率非常低，这主要由两个问题导致。第一个问题是在初始过程中宿主基因组靶位点诱导双链断裂（DSB）的效率较低。第二个问题是靶位点与携带同源臂和外源基因的供体质粒之间的同源重组修复（HDR）效率较低。HDR是转基因定点整合最常见的机制。DSB主要通过两种相互竞争的机制刺激DNA修复，即HDR和非同源末端连接（NHEJ）。因此，激活HDR或抑制NHEJ可以在整合过程中促进HDR，从而优化转基因的特异性靶向。在本综述中，我们总结了转基因技术中外源转基因定点整合策略的最新进展。
