title: Faithful activation of an extra-bright red fluorescent protein in "knock-in" Cre-reporter mice ideally suited for lineage tracing studies.
abstract: 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.
authors.affiliation: Institute of Immunology, University Clinics Ulm, Ulm, Germany.
authors.forename: Hervé
authors.initials: H
authors.lastname: Luche
authors.forename: Odile
authors.initials: O
authors.lastname: Weber
authors.forename: Tata
authors.initials: T
authors.lastname: Nageswara Rao
authors.forename: Carmen
authors.initials: C
authors.lastname: Blum
authors.forename: Hans Jörg
authors.initials: HJ
authors.lastname: Fehling
mesh_terms: D000818:Animals; D002460:Cell Line; D019070:Cell Lineage / Q000235:genetics; D003433:Crosses, Genetic; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D019426:Integrases / Q000235:genetics*; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics; D000097573:Red Fluorescent Protein
chemical_list: D016326:Extracellular Matrix Proteins; D019426:Integrases; D008164:Luminescent Proteins; D008249:Protein-Lysine 6-Oxidase; D000097573:Red Fluorescent Protein; C077112:Lox protein, mouse; C045073:Cre recombinase