Investigating the role of Wnt/β-catenin signaling during embryonic mammary gland development

The Wnt/β-catenin signaling pathway is crucial for the development of variety of organs including the mammary gland. However, the precise role of Wnt/β-catenin signaling during embryonic mammary gland morphogenesis is still poorly understood. Here, we used an epithelial gain-of-function β-catenin mouse model to study the role of Wnt/β-catenin signaling in embryonic mammary gland development and profiled the transcriptomes of E13.5 and E16.5 control and mutant mammary epithelia. Ctnn1bflox3/flox3 female mice (Harada et al., 1999) were crossed with Krt14Cre/wt male mice (Huelsken et al., 2001) to delete exon 3 of Ctnn1b (encoding ß-catenin) in epithelial cells. The resulting Krt14Cre/wt; Ctnn1bflox3/wt embryos express one allele encoding wild type and one allele stabilized-β-catenin, respectively . The Krt14wt/wt; Ctnn1bflox3/wt littermate embryos were used as controls. To obtain the mammary epithelial samples, the ventral skin of E13.5 and E16.5 embryos were isolated followed by treatment with Dispase II and Pancreatin-Trypsin. Mammary epithelia from mammary buds 1-3 were manually microdissected under a dissecting microscope with fine needles. Tissues from 2-3 embryos from the same litter and same genotype were pooled for one sample before RNA extraction; for E13.5 both male and female embryos were used, whereas for E16.5 samples, only female embryos were used. Four (E13.5) or five (E16.5) biological replicates were collected from minimum three different litters.