Figure 3. Tissue-specific overexpression of PDX-1 using the Cre/loxP-mediated system.

We previously generated CAG-CAT-PDX-1 mice, a transgenic line which constitutively expresses the PDX-1 gene under the control of the chicken β-actin gene (CAG) promoter after the removal of the floxed stuffer sequence (CAT) by Cre-mediated recombination. When the mice were crossed with Ptf1a-Cre mice, which express the Cre recombinase driven by the Ptf1a (PTF1-p48) gene promoter, PDX-1 was expressed in precursors of all three pancreatic cell types: islets, acini, and ducts. In addition, when the mice were crossed with Alb-Cre mice, which express the Cre recombinase driven by the rat albumin gene promoter, PDX-1 was expressed in hepatocytes and cholangiocytes.