德国马克斯·普朗克生物化学研究所Jürgen M. Plitzko小组在研究中取得进展。他们提出了冷冻电子断层扫描完整组织中复制反转录转座子的细胞内结构和快照。相关论文于2025年3月5日发表在《细胞》杂志上。
在这项研究中，研究小组采用冷冻聚焦离子束（FIB）铣削和提升方法来观察卵巢细胞和完整卵室中的复制体VLP，将原位复制体衣壳结构分解为7.7Å低温电子层析成像（cryo-ET）。尽管细胞质复制体VLPs的大小不同，但核VLPs是同质的，并形成密集的排列，支持核输入作为大小选择器的模型。通过分析缺乏TE抑制PIWI相互作用RNA （piRNA）途径的果蝇，研究小组观察到在精子发生过程中，复制体易位到细胞核中。他们的发现提供了对活性LTR反转录转座子的复制周期和细胞结构生物学的见解。
据介绍，长末端重复（LTR）逆转录转座子属于转座元件（TE），自主复制整合到宿主基因组的遗传元件。在动物中，黑腹果蝇是TE研究的重要模式生物，含有多个LTR逆转录转座子，包括Ty1-copia家族，该家族与逆转录病毒主题进化相关，并形成病毒样颗粒（VLP）。
附：英文原文
Title: In-cell structure and snapshots of copia retrotransposons in intact tissue by cryoelectron tomography
Author: Sven Klumpe, Kirsten A. Senti, Florian Beck, Jenny Sachweh, Bernhard Hampoelz, Paolo Ronchi, Viola Oorschot, Marlene Brandstetter, Assa Yeroslaviz, John A.G. Briggs, Julius Brennecke, Martin Beck, Jürgen M. Plitzko
Issue&Volume: 2025-03-05
Abstract: Long terminal repeat (LTR) retrotransposons belong to the transposable elements (TEs), autonomously replicating genetic elements that integrate into the host’s genome. Among animals, Drosophila melanogaster serves as an important model organism for TE research and contains several LTR retrotransposons, including the Ty1-copia family, which is evolutionarily related to retroviruses and forms virus-like particles (VLPs). In this study, we use cryo-focused ion beam (FIB) milling and lift-out approaches to visualize copia VLPs in ovarian cells and intact egg chambers, resolving the in situ copia capsid structure to 7.7 Å resolution by cryoelectron tomography (cryo-ET). Although cytoplasmic copia VLPs vary in size, nuclear VLPs are homogeneous and form densely packed clusters, supporting a model in which nuclear import acts as a size selector. Analyzing flies deficient in the TE-suppressing PIWI-interacting RNA (piRNA) pathway, we observe copia’s translocation into the nucleus during spermatogenesis. Our findings provide insights into the replication cycle and cellular structural biology of an active LTR retrotransposon.
DOI: 10.1016/j.cell.2025.02.003
Source: https://www.cell.com/cell/abstract/S0092-8674(25)00159-X