Specific and efficient ablation of IRP2 in intestinal epithelial cells (IECs), hepatocytes, or macrophages. (A) Schematic representation of the floxed (flox) and the truncated (Δ) Ireb2 alleles. The exon flanked by loxP sites (triangles) is marked with an asterisk. Excision of this exon upon Cre-mediated recombination generates a functional null allele.¹²  (B) The tissue specificity of Cre-mediated truncation of the floxed Ireb2 allele was determined by Southern blot analysis of various tissues from Ireb2^flox/flox mice expressing the Cre recombinase under the control, respectively, of the Villin (Ireb2^VilCre), the Albumin/Alpha fetoprotein (Ireb2^AlfpCre), or the LysozymeM (Ireb2^LysMCre) promoter, as indicated. The EcoRI restriction sites (indicated E) and the probe used (pb1) are shown in panel A. Tail DNA from mice with intact floxed Ireb2 alleles (Ireb2^flox/flox) or from mice with total and constitutive truncation of the Ireb2 locus (Ireb2^Δ/Δ) was used as a control. The floxed (flox) and truncated (Δ) alleles are indicated by arrows. The efficiency of IRP2 ablation in the intestine, the liver, and macrophages, respectively, of Ireb2^VilCre (C), Ireb2^AlfpCre (D), and Ireb2^LysMCre (E) mice expressing (+) or not expressing (−) Cre was assessed by Western blotting. (C) IRP2 expression in whole duodenal tissue samples (lanes 1- 2), in mucosal scrapings (lanes 3-4), and in the submucosal, nonepithelial tissue (lanes 5-6) from Ireb2^VilCre(+) mice (lanes 2, 4, and 6) versus Ireb2^VilCre(−) littermates (lanes 1, 3, and 5). SLC27A4 was used as a mucosal marker. (D) IRP2 levels were assayed in whole liver samples from Ireb2^AlfpCre(+) mice versus Ireb2^AlfpCre(−) littermates, as indicated. (E) IRP2 expression was examined in peritoneal (PΦM) and bone marrow–derived macrophages (BMDMs) from Ireb2^LysMCre(+) mice versus Ireb2^LysMCre(−) littermates, as indicated. IRP1 levels and Cre expression were verified in every sample analyzed. β-Actin was used as a loading control. Representative results of at least 3 experiments are presented. Vertical lines have been inserted to indicate repositioned gel lanes.