Long-Term Expansion of Basal Cells and Novel Differentiation Methods Identify Mechanisms for Switching Claudin Expression in Normal Epithelia

The study developed a culture method for the long-term expansion of primary mammary basal cells and a differentiation method to investigate Claudin expression in epithelia. By removing specific compounds, researchers could switch differentiation states and analyze microarray data to identify key transcription factors. EGR1 was found to suppress Claudin expression in undifferentiated cells by maintaining TWIST1, while ELF3 in differentiated cells facilitated actin organization and Claudin localization, linked to GRHL3. These findings provide a tool for understanding Claudin regulation in basal cell differentiation, with implications for epithelial cell biology, cancer research, and regenerative medicine.