To generate the CD11c-Cre transgene, the 160-kb mouse genomic BAC clone RP24-361C4 (BACPAC Resources) was modified by ET recombination, as previously described (43 (link)). The clone contains the entire Itgax (CD11c) gene but lacks the 5′ end of the adjacent Itgam (CD11b) gene, preventing the overexpression of the latter. The recombination cassette containing the Cre recombinase open reading frame, followed by the bovine growth hormone (BGH) polyA signal and the FRT site-flanked prokaryotic Zeocin resistance cassette (ZeoR), replaced the coding part of the first CD11c exon, and the ZeoR cassette was subsequently removed by FLP-mediated recombination. The clone insert was released from the vector backbone using NotI digestion, gel-purified, and microinjected into fertilized oocytes. The founder line containing two copies of the transgene (as determined by quantitative Southern hybridization) was chosen for further analysis. Mice were genotyped by genomic PCR using either generic Cre primers or primers specific for the CD11c-Cre transgene (5′-ACTTGGCAGCTGTCTCCAAG-3′ and 5′-GCGAACATCTTCAGGTTCTG-3′ were specific for the CD11c promoter and Cre, respectively).
The R26-EYFP strain (21 (link)) was provided by F. Costantini (Columbia University, New York, NY). The RBP-Jfl strain (19 (link)) was provided by L. Hennighausen (National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD), with permission from T. Honjo (Kyoto University, Kyoto, Japan). The Mx1-Cre strain was previously described (44 (link)). Cre-negative RBP-Jfl/fl littermates of CKO (RBP-Jfl/fl Cre+) mice were used as controls; in preliminary experiments, wild-type CD11c-Cre+ mice were used as controls and were found indistinguishable from CD11c-Cre− animals. For inducible RBP-J deletion, adult RBP-Jfl/fl Mx1-Cre+ or control RBP-Jfl/fl mice were injected with 0.25 mg poly(I):(C) three times, with 2-d intervals, and analyzed 3 wk later. For hematopoietic reconstitution, 3 × 106 total BM cells per mouse were injected i.v. into lethally irradiated C57BL/6 mice congenic for CD45.1. The recipient mice were analyzed 4–5 wk after reconstitution. Mice were maintained in a specific pathogen-free facility and used according to the protocol approved by the Columbia University's Institutional Animal Care and Use Committee.
The R26-EYFP strain (21 (link)) was provided by F. Costantini (Columbia University, New York, NY). The RBP-Jfl strain (19 (link)) was provided by L. Hennighausen (National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD), with permission from T. Honjo (Kyoto University, Kyoto, Japan). The Mx1-Cre strain was previously described (44 (link)). Cre-negative RBP-Jfl/fl littermates of CKO (RBP-Jfl/fl Cre+) mice were used as controls; in preliminary experiments, wild-type CD11c-Cre+ mice were used as controls and were found indistinguishable from CD11c-Cre− animals. For inducible RBP-J deletion, adult RBP-Jfl/fl Mx1-Cre+ or control RBP-Jfl/fl mice were injected with 0.25 mg poly(I):(C) three times, with 2-d intervals, and analyzed 3 wk later. For hematopoietic reconstitution, 3 × 106 total BM cells per mouse were injected i.v. into lethally irradiated C57BL/6 mice congenic for CD45.1. The recipient mice were analyzed 4–5 wk after reconstitution. Mice were maintained in a specific pathogen-free facility and used according to the protocol approved by the Columbia University's Institutional Animal Care and Use Committee.