The wind rose of human keratinocyte cell fate

Extensive efforts have been made to understand the molecular actors that control epithelial cell fate. Although pieces of information have been obtained from single-gene function investigations, the entire picture of the molecular mechanisms involved in the regulation of epithelial homeostasis is still mysterious. Growing data indicate that gene networks rather than single "master" genes dictate cell fate. In an attempt to characterize such gene networks, we have been investigating the human keratinocyte proliferation and differentiation genes that act downstream of the transcription factor p63, a major regulator of epidermal homeostasis. We identified two networks: the cell cycle network that controls cell proliferation and the keratinocyte cell fate network. Through further analysis of the existing data on epithelial tumorigenesis and induced pluripotent stem cells, we propose a wind rose model of cell fate that is based on a balance between these two different networks that ultimately control human keratinocyte fate and epidermal homeostasis.