Regulation of LINE-1 in mammals.

Transposable elements (TEs) are mobile DNA elements that represent almost half of the human genome. Transposition of TEs has been implicated as a source of genome evolution and acquisition of new traits but also as an origin of diseases. The activity of these elements is therefore tightly regulated during the life cycle of each individual, and many recent discoveries involved the genetic and epigenetic mechanisms in their control. In this review, we present recent findings in this field of research, focusing on the case of one specific family of TEs: the long-interspersed nuclear elements-1 (LINE-1 or L1). LINE-1 elements are the most representative class of retrotransposons in mammalian genomes. We illustrate how these elements are conserved between mice and humans, and how they are regulated during the life cycle. Additionally, recent advances in genome-wide sequencing approaches allow us not only to better understand the regulation of LINE-1 but also highlight new issues specifically at the bioinformatics level. Therefore, we discuss the state of the art in analyzing such bioinformatics datasets to identify epigenetic regulators of repeated elements in the human genomes.