Faithful activation of an extra-bright red fluorescent protein in "knock-in" Cre-reporter mice ideally suited for lineage tracing studies

Eur J Immunol. 2007 Jan;37(1):43-53. doi: 10.1002/eji.200636745.


The considerable potential of Cre recombinase as a tool for in vivo fate-mapping studies depends on the availability of reliable reporter mice. By targeting a tandem-dimer red fluorescent protein (tdRFP) with advanced spectral and biological properties into the ubiquitously expressed ROSA26 locus of C57BL/6-ES cells, we have generated a novel inbred Cre-reporter mouse with several unique characteristics. We directly demonstrate the usefulness of our reporter strain in inter-crosses with a "universal Cre-deleter" strain and with mice expressing Cre recombinase in a T lineage-specific manner. Cytofluorometric and histological analyses illustrate: (i) non-toxicity and extraordinary brightness of the fluorescent reporter, allowing quantitative detection and purification of labeled cells with highest accuracy, (ii) reliable Cre-mediated activation of tdRFP from an antisense orientation relative to ROSA26 transcription, effectively excluding "leaky" reporter expression, (iii) absence of gene expression variegation effects, (iv) quantitative detection of tdRFP-expressing cells even in paraformaldehyde-fixed tissue sections, and (v) full compatibility with GFP/YFP-based fluorescent markers in multicolor experiments. Taken together, the data show that our C57BL/6-inbred reporter mice are ideally suited for sophisticated lineage-tracing experiments requiring sensitive and quantitative detection/purification of live Cre-expressing cells and their progeny.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cell Lineage / genetics
  • Crosses, Genetic
  • Extracellular Matrix Proteins / genetics
  • Female
  • Gene Expression Regulation*
  • Genes, Reporter*
  • Integrases / genetics*
  • Luminescent Proteins / biosynthesis
  • Luminescent Proteins / genetics*
  • Luminescent Proteins / metabolism*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Inbred DBA
  • Mice, Inbred Strains
  • Mice, Mutant Strains
  • Mice, Transgenic
  • Protein-Lysine 6-Oxidase / genetics


  • Extracellular Matrix Proteins
  • Luminescent Proteins
  • red fluorescent protein
  • Lox protein, mouse
  • Protein-Lysine 6-Oxidase
  • Cre recombinase
  • Integrases