Fig. 6
From: Transposable elements in the mammalian embryo: pioneers surviving through stealth and service
Long interspersed element-1 (L1) contributes to somatic mosaicism. L1 mobilizes in the brain and early embryo (left) and may, for example: a insert into protein-coding exons; b influence neighboring genes by the spreading of repressive histone modifications, such as methylation (me); c initiate sense or antisense transcription of neighboring genes, thereby creating new transcripts, including open reading frame 0 (ORF0) fusion transcripts, using host gene provided splice acceptor sites, which are translated to fusion proteins; d generate DNA double-strand breaks via the endonuclease activity of L1 ORF2p; and e lead to premature termination of host gene transcripts by providing alternative poly(A) signals