334: LINE-1 Recombination with Diverse RNAs

Law C-T et al., Cell Genomics - Law and Burns introduce TiMEstamp, a comparative-genomics pipeline that dates LINE-1 insertions from multiple sequence alignments and discovers hundreds of LINE-1 chimeric insertions fused to diverse RNAs across mammalian evolution. Key terms: LINE-1, TiMEstamp, chimeric insertions, retrotransposition, comparative genomics. Study Highlights:The authors developed TiMEstamp to infer TE insertion times from multispecies MSAs and to detect contemporaneous 5′ sequences fused to LINE-1. They compiled a large catalog of LINE-1 chimeras (reported >700 events) including known U6/LINE-1 cases and newly identified partners such as tRNA, 28S rRNA, 7SL, Y RNA, Alu elements, and mRNA 5′ transductions. Alu/LINE-1 chimeras (452 events) and 17 mRNA/lncRNA 5′ transductions were characterized with TSDs, EN motifs, and orientation/length patterns. They also show that promoter co-option (e.g., RAP1GDS1 driving a spliced intronic L1PA2) can restore retrotransposition competence. Conclusion:Comparative MSA-based timing reveals widespread, recurrent recombination between LINE-1 RNA and diverse cellular RNAs, producing chimeric insertions that have contributed to transposon diversification and provide mechanisms (RNA ligation, template switching, twin priming, promoter co-option) that may influence TE evolution and somatic/germline retrotransposition. Music:Enjoy the music based on this article at the end of the episode. Article title:Comparative genomics reveals LINE-1 recombination with diverse RNAs First author:Law C-T Journal:Cell Genomics DOI:10.1016/j.xgen.2026.101165 Reference:Law C-T and Burns K.H., 2026. Comparative genomics reveals LINE-1 recombination with diverse RNAs. Cell Genomics 6, 101165. https://doi.org/10.1016/j.xgen.2026.101165 License:This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/ Support:Base by Base – Stripe donations: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00 Official website https://basebybase.com On PaperCast Base by Base you’ll discover the latest in genomics, functional genomics, structural genomics, and proteomics. Episode link: https://basebybase.com/episodes/line1-recombination-diverse-rnas QC:This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-04-05. QC Scope:- article metadata and core scientific claims from the narration- excludes analogies, intro/outro, and music- transcript coverage: Audited sections covering the TiMEstamp workflow and data (MSA across mammals), discovery of chimeric LINE-1 insertions (tRNA halves, 28S rRNA, 7SL, Y RNA, 7SK), Alu/LINE-1 chimeras, mRNA/lncRNA 5' transductions (MAP3K13, FHIT), RAP1GDS1 promoter co-option, twin priming and trans-splicing mechanisms, and study limitati- transcript topics: LINE-1 retrotransposition mechanics (TPRT); TiMEstamp methodology and MSA dating; Chimeric LINE-1 insertions with non-LINE-1 RNAs (tRNA halves, 28S rRNA, 7SL, Y RNA, 7SK RNA); Alu/LINE-1 chimeras and temporal activity; 5′ transductions involving mRNAs/lncRNAs (MAP3K13, FHIT, RAP1GDS1); RAP1GDS1 promoter co-option and transcriptional rescue QC Summary:- factual score: 10/10- metadata score: 10/10- supported core claims: 7- claims flagged for review: 0- metadata checks passed: 4- metadata issues found: 0 Metadata Audited:- article_doi- article_title- article_journal- license Factual Items Audited:- TiMEstamp uses MSAs across mammals to date LINE-1 insertions and identify contemporaneous adjacencies- Chimeric LINE-1 insertions involve diverse RNAs including tR...