title: Spontaneous ectopic recombination in cell-type-specific Cre mice removes loxP-flanked marker cassettes in vivo.
abstract: Conditional gene targeting using the Cre/loxP technology generally includes integration of a selection marker cassette flanked by loxP recognition sites (floxed) in the target gene locus. Subsequent marker removal avoids possible impairment of gene expression or mosaicism due to partial and total deletions after Cre-mediated recombination in vivo. The use of deleter Cre mice for in vivo marker removal in floxed connexin43 mice revealed considerable mosaicism, but no selective marker removal. In addition, we noted that several Cre transgenic lines displayed spontaneous ectopic activity, reminiscent of deleter Cre mice, and required the confirmation of cell type-specific deletion in every individual mouse. When we used myosin heavy chain promoter Cre (alphaMyHC-Cre) mice for cardiomyocyte specific deletion, we observed, in addition to cardiomyocyte-restricted or complete excision, selective marker removal in a subgroup of mice as well. Thus, selective marker removal can be achieved as a byproduct of cell-type restricted deletion.
authors.forename: Dominik
authors.initials: D
authors.lastname: Eckardt
authors.forename: Martin
authors.initials: M
authors.lastname: Theis
authors.forename: Britta
authors.initials: B
authors.lastname: Döring
authors.forename: Dina
authors.initials: D
authors.lastname: Speidel
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
authors.forename: Thomas
authors.initials: T
authors.lastname: Ott
mesh_terms: D000483:Alleles; D000818:Animals; D001287:Attachment Sites, Microbiological / Q000235:genetics*; D015139:Blotting, Southern; D000072259:Connexin 26; D018031:Connexin 43 / Q000235:genetics; D017630:Connexins / Q000235:genetics; D004274:DNA, Recombinant / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods*; D005819:Genetic Markers / Q000235:genetics*; D019426:Integrases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009030:Mosaicism; D016254:Mutagenesis, Insertional / Q000235:genetics*; D009928:Organ Specificity; D011995:Recombination, Genetic / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics*; D019076:Transgenes / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018031:Connexin 43; D017630:Connexins; D004274:DNA, Recombinant; D005819:Genetic Markers; D014764:Viral Proteins; D000072259:Connexin 26; C045073:Cre recombinase; D019426:Integrases