Transgenic Research

, Volume 16, Issue 5, pp 657–660

Excision of the Frt-flanked neoR cassette from the CD19cre knock-in transgene reduces Cre-mediated recombination

  • Marc Schmidt-Supprian
  • F. Thomas Wunderlich
  • Klaus Rajewsky
Technical Report

DOI: 10.1007/s11248-007-9100-4

Cite this article as:
Schmidt-Supprian, M., Wunderlich, F.T. & Rajewsky, K. Transgenic Res (2007) 16: 657. doi:10.1007/s11248-007-9100-4

Abstract

Intercross of mice transgenic for Flp-recombinase with the CD19cre mouse strain leads to excision of the Frt-flanked neoR cassette from the CD19cre knock-in transgene. This significantly reduces the expression level of Cre by the CD19cre transgene and consequently decreases the extent of Cre-mediated recombination of loxP-flanked alleles, most likely due to the fact that this neoR cassette contains polyoma enhancer sequences. We wish to draw attention to this finding, since the Flp-deleter mouse strain is commonly used to remove Frt-flanked selection cassettes in vivo from conditional alleles. Therefore conditional alleles have to be separated from the Flp-deleter transgene by breeding before crosses with CD19cre mice are initiated. In addition our findings suggest that gene expression from the CD19 locus can be increased by the insertion of exogenous enhancer sequences, without compromising B cell specificity.

Keywords

CD19cre mouse stain Conditional gene targeting efficiency B cells Frt-site flanked neomycin resistance gene cassette 

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Marc Schmidt-Supprian
    • 1
  • F. Thomas Wunderlich
    • 2
  • Klaus Rajewsky
    • 1
  1. 1.The CBR Institute for Biomedical ResearchHarvard Medical SchoolBostonUSA
  2. 2.Institute for GeneticsUniversity of CologneCologneGermany

Personalised recommendations