Colonna Romano Nunzia, Fanti Laura
Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "Charles Darwin", "Sapienza" University of Rome, 00185 Rome, Italy.
Cells. 2022 Mar 19;11(6):1048. doi: 10.3390/cells11061048.
Transposable elements (TEs) are ubiquitous genetic elements, able to jump from one location of the genome to another, in all organisms. For this reason, on the one hand, TEs can induce deleterious mutations, causing dysfunction, disease and even lethality in individuals. On the other hand, TEs can increase genetic variability, making populations better equipped to respond adaptively to environmental change. To counteract the deleterious effects of TEs, organisms have evolved strategies to avoid their activation. However, their mobilization does occur. Usually, TEs are maintained silent through several mechanisms, but they can be reactivated during certain developmental windows. Moreover, TEs can become de-repressed because of drastic changes in the external environment. Here, we describe the 'double life' of TEs, being both 'parasites' and 'symbionts' of the genome. We also argue that the transposition of TEs contributes to two important evolutionary processes: the temporal dynamic of evolution and the induction of genetic variability. Finally, we discuss how the interplay between two TE-dependent phenomena, insertional mutagenesis and epigenetic plasticity, plays a role in the process of evolution.
转座元件（TEs）是普遍存在的遗传元件，在所有生物体中都能够从基因组的一个位置跳跃到另一个位置。因此，一方面，转座元件可诱导有害突变，导致个体功能障碍、疾病甚至死亡。另一方面，转座元件可增加遗传变异性，使种群更有能力适应性地应对环境变化。为了抵消转座元件的有害影响，生物体进化出了避免其激活的策略。然而，它们的移动确实会发生。通常，转座元件通过多种机制保持沉默，但它们可在某些发育阶段被重新激活。此外，由于外部环境的剧烈变化，转座元件可能会被去抑制。在这里，我们描述了转座元件的“双重生活”，它们既是基因组的“寄生虫”，也是“共生体”。我们还认为，转座元件的转座作用促成了两个重要的进化过程：进化的时间动态和遗传变异性的诱导。最后，我们讨论了两种依赖转座元件的现象——插入诱变和表观遗传可塑性之间的相互作用如何在进化过程中发挥作用。
