Transposable elements shape the evolution of mammalian development

In this Review, Senft and Macfarlan discuss the diverse ways by which transposable elements (TEs) contribute to mammalian development and evolution, including direct contributions through TE-derived regulatory elements, RNAs and proteins, as well as indirect effects through the evolution of a TE repression system, the Kruppel-associated box zinc finger proteins (KRAB-ZFPs). Transposable elements (TEs) promote genetic innovation but also threaten genome stability. Despite multiple layers of host defence, TEs actively shape mammalian-specific developmental processes, particularly during pre-implantation and extra-embryonic development and at the maternal-fetal interface. Here, we review how TEs influence mammalian genomes both directly by providing the raw material for genetic change and indirectly via co-evolving TE-binding Kruppel-associated box zinc finger proteins (KRAB-ZFPs). Throughout mammalian evolution, individual activities of ancient TEs were co-opted to enable invasive placentation that characterizes live-born mammals. By contrast, the widespread activity of evolutionarily young TEs may reflect an ongoing co-evolution that continues to impact mammalian development.

Automated summary

Transposable elements (TEs) play a significant role in mammalian development and evolution by directly contributing genetic materials and indirectly affecting the evolution of TE repression systems such as KRAB-ZFPs. Despite the threats to genome stability, TEs actively shape mammalian-specific developmental processes and continue to impact mammalian development through ongoing co-evolution.