近日，Kathleen Collins及其小组提出了不同的修复途径支持完整或截断的R2反转录转座子蛋白插入。这一研究成果发表在2025年11月13日出版的国际学术期刊《科学》上。

研究人员筛选了通过R2反转录转座子蛋白影响位点特异性转基因合成进入人类基因组的细胞因子。课题组发现，插入长度和连接特征的不同是基于不同的修复过程，包括ATR依赖的聚合酶θ末端连接，53BP1导向的屏蔽蛋白/CST-Polα-引物酶填充合成，或依赖于CtIP-MRN的有限链退火。这些发现揭示了由非LTR反转录转座子蛋白合成的基因组引物cDNA如何支持稳定的新基因插入，对天然反转录转座子的迁移和基因组工程具有重要意义。

据了解，非LTR逆转录转座子蛋白通过靶向引物逆转录的协调切口和逆转录酶活性将其RNA模板复制到基因组中。第一链cDNA成为稳定插入双链的机制，包括cDNA 3 '端结形成和第二链合成的要求，尚不清楚。

附：英文原文

Title: Different repair pathways support intact or truncated insertions by R2 retrotransposon protein

Author: Jeremy J. R. McIntyre, Connor A. Horton, Kathleen Collins

Issue&Volume: 2025-11-13

Abstract: Non-LTR retrotransposon proteins copy their RNA template into a genome via coordinated nicking and reverse transcriptase activities of target-primed reverse transcription. Mechanisms by which the first-strand cDNA becomes stably inserted duplex, including requirements for junction formation at the cDNA 3′ end and second-strand synthesis, are unknown. We screened for cellular factors that influence site-specific transgene synthesis into the human genome by an R2 retrotransposon protein. We discover that insertion lengths and junction signatures differ based on alternative repair processes involving ATR-dependent Polymerase θ end-joining, 53BP1-directed Shieldin/CST-Polα-primase fill-in synthesis, or limited strand annealing dependent on CtIP-MRN. These insights shed light on how genome-primed cDNA synthesis by a non-LTR retrotransposon protein can support stable new gene insertion, with major implications for native retrotransposon mobility and genome engineering.

DOI: adz3121

Source: https://www.science.org/doi/10.1126/science.adz3121