Deregulated Nras expression in knock-in animals harboring a gammaretroviral long terminal repeat at the Nras/Csde1 locus

PLoS One. 2013;8(2):e56029. doi: 10.1371/journal.pone.0056029. Epub 2013 Feb 13.

Abstract

To investigate mechanisms and phenotypic effects of insertional mutagenesis by gammaretroviruses, we have developed mouse lines containing a single Akv 1-99 long terminal repeat (LTR) and a floxed PGK/Tn5 neomycin cassette at the Nras proto-oncogene at positions previously identified as viral integration sites in Akv 1-99 induced tumors. The insert did not compromise the embryonic development, however, the cassette had an effect on Nras expression in all tissues analyzed. Cre-mediated excision of the PGK/Tn5 neomycin cassette in two of the lines caused upregulation of Nras. Altogether, the knock-in alleles are characterized by modulation of expression of the target gene from more than ten-fold upregulation to three-fold downregulation and exemplify various mechanisms of deregulation by insertional mutagenesis. LTR knock-in mice may serve as a tool to investigate mechanisms of retroviral insertional mutagenesis and as a way of constitutive or induced modulation of expression of a target gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Gammaretrovirus / genetics*
  • Gammaretrovirus / metabolism
  • Genes, ras / genetics*
  • Mice
  • Mutagenesis, Insertional
  • Terminal Repeat Sequences*
  • Virus Integration*

Grants and funding

This study was supported in part by grants from the Danish Cancer Society, the Danish Medical Research Council and the Danish Genetically Modified Animal Resource (DAGMAR) funded by the Danish Agency for Science, Technology, and Innovation. No additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.