Signaling networks of developing hair follicles

The hair follicle (HF) is a complex miniorgan that serves as an ideal model system to study stem cell (SC) interactions with the niche during growth and regeneration. Dermal papilla (DP) cells are required for activating SCs during the adult hair cycle, but the signal exchange between niche and SC precursors/transit amplifying progenitor cells (TACs) that regulates HF morphogenetic growth is largely unknown. Here we use six transgenic reporters to isolate 14 major skin and HF cell populations. With next-generation RNA sequencing we characterize their transcriptomes and define unique molecular signatures. SC precursors, TACs and the DP niche express a plethora of known and novel ligands and receptors. Signaling interaction network analysis reveals a birds-eye view of pathways implicated in epithelial-mesenchymal interactions. Using a systematic tissue-wide approach this work provides a comprehensive platform, linked to an interactive online database, to identify and further explore the SC/TAC/niche crosstalk regulating HF growth. Overall design: FACS was used to isolate specific cell types from P5 mouse back skin

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Rezza A, Wang Z, Sennett R, Qiao W, Wang D, Heitman N, Mok KW, Clavel C, Yi R, Zandstra P, Ma'ayan A, Rendl M