Role of Stress in the Spread of Transposable Elements

Abstract

Background: Transposable elements (TEs) and genomes have been at war for millions of years. On one hand, genomes developed epigenetic systems to inactivate TEs. On the other hand, it appears that TEs can take advantage of stress to evade the genome’s repressing systems and spread throughout the genome. However, until recently it was unclear how and why stress influences transposable elements’ movement. In this review, we explore the mechanisms involved in TE stress-induced activation. Methods: The first part of the review looks into epigenetic mechanisms, its 19 references were taken from Handbook of Epigenetics 2nd edition (1) and reviews (2) (3). The rest of the studies presented in this review were drawn from searches done on Web of Science with the terms: TS=((Transposable element* OR mobile genetic element*) AND (Stress or Evolution) AND (Activation)) with peer-reviewed articles and reviews written in English included only. The search yielded 401 results and 56 were estimated relevant and of sufficient quality to be selected. Summary: The main conclusion reached by this review is that protection mechanisms against TEs movement, which are mostly epigenetic, are compromised by the presence of stress. Additionally, TEs themselves evolved diverse tools to promote their activation under certain stress conditions allowing them to evade the repression imposed by the genome. These two mechanisms provide opportunities for TEs to move around the genome and create genetic diversity during stress episodes. As such, TEs stress induced mobility certainly played a major role in the rapid adaption of populations and its impact can be witnessed across genomes.