<i>FGF20</i> Secreted From Dermal Papilla Cells Regulate the Proliferation and Differentiation of Hair Follicle Stem Cells in Fine‐Wool Sheep

Wool traits determine the market value of fine-wool sheep, and wool fibre-breaking elongation (fibres can be stretched or elongated before they break) is one of the important wool traits. The interaction between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) determines hair follicle development in fine wool sheep, thereby directly influencing wool traits. A genome-wide association study based on pre-sequencing data identified FGF20, which was significantly associated with wool fibre-breaking elongation. The study reveals that the regulatory mechanism of FGF20 secreted from DPCs affects the proliferation and differentiation of HFSCs through a co-culture system, to provide a new perspective for fine-wool sheep breeding. After knocking down FGF20 expression in DPCs, the results showed that the expression of fibroblast growth factor receptor 2 (FGFR2) and fibroblast growth factor receptor 3 (FGFR3) in DPCs and HFSCs was significantly decreased (p < 0.05), the number of EdU-positive cells and cell viability was significantly decreased (p < 0.01), and the apoptosis rate was significantly increased (p < 0.05). Meanwhile, the differentiation markers of SOX9, NOTCH1 and β-Catenin in HFSCs were also significantly reduced (p < 0.05). These findings indicate that FGF20-knockdown in DPCs of fine-wool sheep inhibits the proliferation and differentiation of HFSCs in the co-culture system, providing a theoretical basis for elucidating the regulatory mechanism of hair follicle self-renewal and differentiation of fine-wool sheep and providing a co-culture system for regenerative medicine.