近日，日本东京大学Tetsuji Kakutani等研究人员合作揭示CENH3染色质在拟南芥中介导的反转录转座子整合。该项研究成果于2025年1月1日在线发表在《自然》杂志上。

研究人员表示，从脊椎动物到植物，着丝粒的主要组分是迅速进化的重复序列，如串联重复（TR）和转座元件（TE）。这些序列承载着特定于着丝粒的组蛋白H3（CENH3）。

最近在人类和拟南芥中确定的完整着丝粒结构表明，反转录转座子在着丝粒的TR区域内频繁整合和清除。尽管“中心向”反转录转座子对着丝粒快速演化的悖论有很大影响，但在任何生物中，着丝粒靶向的机制仍然不太清楚。

研究人员展示了Ty3和Ty1长末端重复反转录转座子如何在拟南芥物种的着丝粒TR区域内快速更替。研究人员证明了Ty1/Copia元素Tal1（拟南芥刺梨1）在拟南芥（Arabidopsis thaliana）中如何新整合到CENH3占据的区域，并且CENH3区域的异位扩展会导致Tal1整合区域的扩展。

嵌合TE的整合谱揭示了关键的结构变异，这些变异负责将转座子从基因丰富的区域转向着丝粒的染色质靶向特异性，而这些区域在这些TE演化过程中反复发生转换。这些发现展示了着丝粒染色质对转座子介导的快速着丝粒进化的影响，这一机制在真核基因组中具有广泛的相关性。

附：英文原文

Title: Centrophilic retrotransposon integration via CENH3 chromatin in Arabidopsis

Author: Tsukahara, Sayuri, Bousios, Alexandros, Perez-Roman, Estela, Yamaguchi, Sota, Leduque, Basile, Nakano, Aimi, Naish, Matthew, Osakabe, Akihisa, Toyoda, Atsushi, Ito, Hidetaka, Edera, Alejandro, Tominaga, Sayaka, Juliarni, Kato, Kae, Oda, Shoko, Inagaki, Soichi, Lorkovi, Zdravko, Nagaki, Kiyotaka, Berger, Frdric, Kawabe, Akira, Quadrana, Leandro, Henderson, Ian, Kakutani, Tetsuji

Issue&Volume: 2025-01-01

Abstract: In organisms ranging from vertebrates to plants, major components of centromeres are rapidly evolving repeat sequences, such as tandem repeats (TRs) and transposable elements (TEs), which harbour centromere-specific histone H3 (CENH3)1,2. Complete centromere structures recently determined in human and Arabidopsis suggest frequent integration and purging of retrotransposons within the TR regions of centromeres3,4,5. Despite the high impact of ‘centrophilic’ retrotransposons on the paradox of rapid centromere evolution, the mechanisms involved in centromere targeting remain poorly understood in any organism. Here we show that both Ty3 and Ty1 long terminal repeat retrotransposons rapidly turnover within the centromeric TRs of Arabidopsis species. We demonstrate that the Ty1/Copia element Tal1 (Transposon of Arabidopsis lyrata 1) integrates de novo into regions occupied by CENH3 in Arabidopsis thaliana, and that ectopic expansion of the CENH3 region results in spread of Tal1 integration regions. The integration spectra of chimeric TEs reveal the key structural variations responsible for contrasting chromatin-targeting specificities to centromeres versus gene-rich regions, which have recurrently converted during the evolution of these TEs. Our findings show the impact of centromeric chromatin on TE-mediated rapid centromere evolution, with relevance across eukaryotic genomes.

DOI: 10.1038/s41586-024-08319-7

Source: https://www.nature.com/articles/s41586-024-08319-7