[SLFN14 inhibits LINE-1 transposition activity]

Long interspersed nuclear element-1 (LINE-1) is the only active autonomous transposon in the human genome. Its transposition frequently induces host genome instability, leading to a variety of genetic diseases, including cancers. The host factors play important roles in inhibiting LINE-1 retrotransposition. As an important component of the immune system, the host factor SLFN14 has antiviral activity. Our laboratory shows that SLFN14 possesses potent inhibitory activity against LINE-1 retrotransposition. To explore the potential mechanism of SLFN14 inhibition, we analyzed its effects on transcription, translation, reverse transcription and insertion in the LINE-1 replication cycle. We confirmed that SLFN14 could suppress the LINE-1 mRNA level by affecting its transcription and degradation, thereby diminishing the protein and cDNA levels of LINE-1, which eventually block the LINE-1 retrotransposition. Further, by mapping the active domains of SLFN14, we found its inhibitory activity on LINE-1 being closely related to its endoribonuclease and ribosome binding domains. These results demonstrate the mechanism of SLFN14 in regulating LINE-1 replication, which further provide new insights for improving the regulation network of host factors for controlling genomic instability caused by LINE-1 replication.