β-catenin Activity in the Dermal Papilla Regulates Morphogenesis and Regeneration of Hair

SummaryThe activity of keratinocytes in the hair follicle is regulated by signals from a specialized mesenchymal niche, the dermal papilla (DP). Here, mice expressing cre recombinase in the DP were developed to probe the interaction between follicular keratinocytes and the DP in vivo. Inactivation of the β-catenin gene within DP of fully developed hair follicles results in dramatically reduced proliferation of the progenitors and their progeny that generate the hair shaft, and, subsequently, premature induction of the destructive phase of the hair cycle. It also prevents regeneration of the cycling follicle from stem cells. Gene expression analysis reveals that β-catenin activity in the DP regulates signaling pathways, including FGF and IGF, that can mediate the DP's inductive effects. This study reveals a signaling loop that employs Wnt/β-catenin signaling in both epithelial progenitor cells and their mesenchymal niche to govern and coordinate the interactions between these compartments to guide hair morphogenesis.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (271 K)Download as PowerPoint slideHighlights► A DP-specific cre line was developed to explore the role of a mesenchymal niche ► β-catenin activity in the DP sustains adjacent keratinocyte progenitors ► Growth factors secreted by DP regulate matrix cell proliferation ► Regeneration of hair follicle from stem cells requires β-catenin activity in DP