长散布元素(LINE),或非长末端重复序列(LTR)反转录转座子,是存在于大多数真核生物基因组DNA中的可移动遗传元件,包含相当一部分宿主染色体。LINE构成内源性诱变剂,其在宿主染色体中引起插入突变并且对宿主基因组进化具有大的影响。尽管它们很重要,然而,LINE逆转转座的分子机制尚不完全清楚。一些研究表明,参与DNA断裂修复的宿主蛋白可调节LINE逆转录转位。最近,我们提供的证据表明,有2种不同的途径-退火和直接-连接LINE的5'端与宿主染色体DNA。这些途径似乎被斑马鱼LINE和人L1在DT40细胞中独特地使用。在HeLa细胞中,似乎只使用退火途径。这意味着2种LINE的不同特征以及宿主因子决定了选择哪种途径。这里,我们讨论了LINE逆转位的5'端连接途径,并提出LINE整合途径采用某些宿主修复因子。
Long interspersed elements (LINEs), or non-long-terminal repeat (LTR) retrotransposons, are mobile genetic elements that exist in the genomic DNA of most eukaryotes, comprising a considerable portion of the host chromosomes. LINEs constitute endogenous mutagens that cause insertional mutations in host chromosomes and have a large impact on host genome evolution. Despite their importance, however, the molecular mechanism of LINE retrotransposition is not fully understood. Several studies suggest that host proteins that participate in the repair of DNA breaks modulate LINE retrotransposition. Recently, we provided evidence that there are 2 distinct pathways-annealing and direct-that join the 5\'-end of LINEs to host chromosomal DNA. These pathways appear to be used distinctively by zebrafish LINEs and the human L1 in DT40 cells. In HeLa cells, only the annealing pathway appears to be used. This implies that different characteristics of the 2 LINEs and also host factors dictate which pathway is selected. Here, we discuss the 5\'-end-joining pathways of LINE retrotransposition and propose that the pathways of LINE integration adopt certain host repair factors.