The Intricate Evolutionary Balance between Transposable Elements and Their Host: Who Will Kick at Goal and Convert the Next Try?

Biology (Basel). 2022 May 6;11(5):710. doi: 10.3390/biology11050710.

Abstract

Transposable elements (TEs) are mobile DNA sequences that can jump from one genomic locus to another and that have colonized the genomes of all living organisms. TE mobilization and accumulation are an important source of genomic innovations that greatly contribute to the host species evolution. To ensure their maintenance and amplification, TE transposition must occur in the germ cell genome. As TE transposition is also a major threat to genome integrity, the outcome of TE mobility in germ cell genomes could be highly dangerous because such mutations are inheritable. Thus, organisms have developed specialized strategies to protect the genome integrity from TE transposition, particularly in germ cells. Such effective TE silencing, together with ongoing mutations and negative selection, should result in the complete elimination of functional TEs from genomes. However, TEs have developed efficient strategies for their maintenance and spreading in populations, particularly by using horizontal transfer to invade the genome of novel species. Here, we discuss how TEs manage to bypass the host's silencing machineries to propagate in its genome and how hosts engage in a fightback against TE invasion and propagation. This shows how TEs and their hosts have been evolving together to achieve a fine balance between transposition and repression.

Keywords: endogenous retroviruses; genomic instability; horizontal transfer; inheritance; piRNA; piRNA cluster; transposable elements.

Publication types

  • Review

Grants and funding

This work was supported by grants from the Agence Nationale pour la Recherche (ANR-CHApiTRE, ANR-BiopiC, and ANR-EpiTET projects), the Association de Recherche Cancer (contract R17155CC). M.Ys was supported by the Ministère de l’Enseignement Supérieur et de la Recherche (MESR) and the Fondation pour la Recherche Medical (FRM) (FDT202106012950). This research is supported by the French government IDEX-ISITE initiative 16-IDEX-0001 (CAP20-25).