Cre activity in fetal albCre mouse hepatocytes: Utility for developmental studies

The albCre transgene, having Cre recombinase driven by the serum albumin (alb) gene promoter, is commonly used to generate adult mice having reliable hepatocyte-specific recombination of loxP-flanked ("floxed") alleles. Based on previous studies, it has been unclear whether albCre transgenes are also reliable in fetal and juvenile mice. Perinatal liver undergoes a dynamic transition from being predominantly hematopoietic to predominantly hepatic. We evaluated Cre activity during this transition in albCre mice using a sensitive two-color fluorescent reporter system. From fetal through adult stages, in situ patterns of Cre-dependent recombination of the reporter closely matched expression of endogenous Alb mRNA or protein, indicating most or all hepatocytes, including those in fetal and juvenile livers, had expressed Cre and recombined the reporter. Our results indicate the albCre transgene is effective in converting simple floxed alleles in fetal and neonatal mice and is an appropriate tool for studies on hepatocyte development.