175 Yap and Notch signaling activities correlate with the two phases of skin epidermal stratification during development

The skin epidermis is transformed during development, through stratification and differentiation, from a simple single-layered epithelium into complex barrier just before birth. However, how epidermal the switch in cell fate basal to suprabasal keratinocytes are achieved at molecular level remain elusive. Understanding crucial important for designing therapies hyperproliferative human diseases such as psoriasis or atopic dermatitis, which may recapitulate developmental programs. Using dynamic growth tissue measurements mouse, we recently proposed two-phase model of development. In first phase, progenitors undergo burst proliferation around embryonic day E13.5 that leads crowding layer onset stratification, where cells pushed upwards form new layers. this study, our data show active nuclear YAP staining temporally correlates with their dynamics, particularly phase. Moreover, Notch downstream target HES1 was highly enriched ∼2% beginning second suggesting these potentially delaminate migrate suprabasally continuously supporting addition, generated Krt10-mNeonGreen knockin suprabasal-reporter mouse line used time-lapse imaging developing skin, identified single delaminating acquiring fate. Based on data, propose working whereby YAP/TAZ signaling drives govern phase whereas regulates cellular delamination.