Project Summary Our global objective is to elucidate the mechanisms underlying tissue homeostasis and regeneration in mammalian skin and to understand how this process goes awry in human disorders, including cancers. Central to achieving this goal is to determine how transcription factors act in concert to specify stem cell behavior, and to ascertain how stem cells respond to stimulating signals from their microenvironment to remodel their chromatin landscape and activate a new program of gene expression to make tissue. Past AR31737 research led to the identification of transcription factors that are selectively expressed by hair follicle (HF) stem cells, and through mouse genetics, we elucidated the consequences of missing each factor. Although each had differential roles in suppressing tissue lineages, the cohort displayed a common function in controlling stemness. This past research now sets the foundation to tackle a series of important questions: (1) What key stemness genes are co-regulated by the cohort of HF stem cell factors and how does their chromatin become remodeled when faced with dramatically changing transcriptional landscapes during lineage progression? Can we exploit this information to develop paradigms for understanding transcriptional control of gene expression in other skin stem cells and/or their progeny? (2) What are the mechanisms controlling how key genes switch between repressed and active states during lineage determination and progression? Do certain transcription factors function as pioneers in initiating these switches, and if so how? (3) How do external niche signals, e.g. WNTs and BMPs, impact transcriptional regulation of adult HF stem cells? (4) Which signaling pathways govern the establishment of stem cells during skin development? To answer these questions, we'll use in vivo FACS, single cell/RNA-seq, ChIP-seq, powerful in vivo RNAi screens, and devise new tools and technologies to explore transcriptional governance of skin stem cells and their tissues. In so doing, we expect to advance our knowledge of tissue homeostasis and to understand stem cell plasticity, namely how stem cells survive when faced with new environments in wound-repair and malignant progression.