Key roles for SRF in embryonic epidermal differentiation

During development, a polarized sheet of epidermal cells undergoes stratification and differentiation to produce the skin barrier. Through mechanisms poorly understood, the process involves adhesion and Notch signaling. To elucidate how epidermal embryogenesis is governed, we conditionally targeted transcription factor serum response factor (SRF), which has been shown to be essential for proper epidermal differentiation in vitro and in vivo. Seeking mechanism, we identified actomyosin-related genes as well-known SRF targets downregulated shortly after ablation. We show that this results in a diminished cortical actomyosin network which fails to regulate the transition of cells from the basal proliferative layer to the suprabasal differentiating layer resulting in an inability of cells to properly execute stratification and differentiation. FACS purification of basal epidermal cells from E16.5 SRF fl/fl ROSA26 YFP fl/fl K14-Cre (cKO) or SRF fl/+ ROSA26 YFP fl/fl K14-Cre (WT) was performed on a FACS Vantage SE system equipped with FACS DiVa software (BD Biosciences). Cells were gated for single events and viability and then sorted according to α6 integrin-PE expression and YFP.