Environment, Cellular Signaling, and L1 Activity

Long INterspersed element‐1 mobility as a sensor of environmental stresses

“…They found that UV exposure could induce an increase of L1Hs promoter activity. Again, this result should not be considered relevant because choriocarcinoma cells are not a naturally UV exposed cell population; also in this case, the reason why this cell line was chosen is just because it was known to support high levels of L1 retrotransposition (Leibold et al ., ); moreover, the reporter used has some major limitations as explained by the same authors (Ade et al ., ). Similar results were obtained by Teneng et al .…”

“…For a long time, it was believed that all somatic cells completely suppressed L1 activity by DNA methylation with patterns established during early gastrulation (Bestor and Bourc'his, ), differently from germinal cells which during gametogenesis could be permissive (Branciforte and Martin, ; Brouha et al ., ; Georgiou et al ., ). Currently, the conceptual model of L1 activity in the host somatic cell has changed in light of subsequent discoveries: (1) the detection of L1 activity, both in various types of cancer cells (Iskow et al ., ; Lee et al ., ; Tubio et al ., ) and in aging/senescent cells (De Cecco et al ., , , ); (2) the finding that healthy somatic cells can become permissive to L1 activity during certain developmental windows, including early embryogenesis (Prak et al ., ; Muotri et al ., ) and neurogenesis (Richardson et al ., ; Suarez et al ., ); (3) the observation that L1‐RTP occurs in cells responding to several environmental stresses (Ishizaka et al ., ; Ade et al ., ; Horváth et al ., ).…”

“…L1 mobility activation could be a potentially useful molecular biomarker to assess and monitor the biological response to disease‐predisposing environmental insults. Indeed, about 100 L1s elements in the human genome are estimated to be retrotransposition competent and their expression could be affected by several environmental exposures (Ishizaka et al ., ; Miousse et al ., ; Ade et al ., ; Horváth et al ., ).…”