The genomic distribution of L1 elements: The role of insertion bias and natural selection

Todd Graham, Stephane Boissinot

Research output: Contribution to journalShort survey

Abstract

LINE-1 (L1) retrotransposons constitute the most successful family of retroelements in mammals and account for as much as 20% of mammalian DNA. L1 elements can be found in all genomic regions but they are far more abundant in AT-rich, gene-poor, and low-recombining regions of the genome. In addition, the sex chromosomes and some genes seem disproportionately enriched in L1 elements. Insertion bias and selective processes can both account for this biased distribution of L1 elements. L1 elements do not appear to insert randomly in the genome and this insertion bias can at least partially explain the genomic distribution of L1. The contrasted distribution of L1 and Alu elements suggests that postinsertional processes play a major role in shaping L1 distribution. The most likely mechanism is the loss of recently integrated L1 elements that are deleterious (negative selection) either because of disruption of gene function or their ability to mediate ectopic recombination. By comparison, the retention of L1 elements because of some positive effect is limited to a small fraction of the genome. Understanding the respective importance of insertion bias and selection will require a better knowledge of insertion mechanisms and the dynamics of L1 inserts in populations.

Original languageEnglish (US)
Article number75327
JournalJournal of Biomedicine and Biotechnology
Volume2006
DOIs
StatePublished - 2006

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Health, Toxicology and Mutagenesis

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