The minimal active human SVA retrotransposon requires only the 5'-hexamer and Alu-like domains

Mol Cell Biol. 2012 Nov;32(22):4718-26. doi: 10.1128/MCB.00860-12. Epub 2012 Sep 24.

Abstract

RNA-based duplication mediated by reverse transcriptase (RT), a process termed retrotransposition, is ongoing in humans and is a source of significant inter- and perhaps intraindividual genomic variation. The long interspersed element 1 (LINE-1 or L1) ORF2 protein is the genomic source for RT activity required for mobilization of its own RNA in cis and other RNAs, such as SINE/variable-number tandem-repeat (VNTR)/Alu (SVA) elements, in trans. SVA elements are ~2-kb hominid-specific noncoding RNAs that have resulted in single-gene disease in humans through insertional mutagenesis or aberrant mRNA splicing. Here, using an SVA retrotransposition cell culture assay in U2OS cells, we investigated SVA domains important in L1-mediated SVA retrotransposition. Partial- and whole-domain deletions revealed that removal of either the Alu-like or SINE-R domain in the context of a full-length SVA has little to no effect, whereas removal of the CT hexamer or the VNTR domain can result in a 75% decrease in activity. Additional experiments demonstrate that the Alu-like fragment alone can retrotranspose at low levels while the addition of the CT hexamer can enhance activity as much as 2-fold compared to that of the full-length SVA. These results suggest that no SVA domain is essential for retrotransposition in U2OS cells and that the 5' end of SVA (hexamer and Alu-like domain) is sufficient for retrotransposition.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alu Elements*
  • Cell Line, Tumor
  • Genes, Reporter
  • Green Fluorescent Proteins
  • Humans
  • Long Interspersed Nucleotide Elements*
  • Minisatellite Repeats
  • Mutagenesis, Insertional
  • RNA, Untranslated / chemistry
  • RNA, Untranslated / genetics*
  • RNA, Untranslated / metabolism
  • RNA-Directed DNA Polymerase / genetics
  • RNA-Directed DNA Polymerase / metabolism
  • Reverse Transcription*

Substances

  • RNA, Untranslated
  • Green Fluorescent Proteins
  • RNA-Directed DNA Polymerase