Effects of all-trans retinoic acid on goat dermal papilla cells cultured in vitro

Background: All-trans retinoic acid (ATRA), a vitamin A-derived active metabolite, exerts important functions in hair biology. Previous studies indicated that excess ATRA hampered hair follicle morphogenesis and cyclic regeneration in adulthood, but other studies stated that ATRA promoted hair growth. Dermal papilla (DP), a cluster of specialized fibroblasts, plays pivotal roles in controlling development and regeneration of hair follicle. Several lines of evidence indicated that DP might be the target cells of ATRA in the hair follicle. To confirm this hypothesis, the present study was performed to explore the biological effects of ATRA on goat dermal papilla cells (DPCs) and clarify the roles of ATRA in hair biology. Results: Our experimental results indicated that key signaling transducers of ATRA were dynamically expressed in distinct stages of goat cashmere growth cycle, and high-dose ATRA treatment (10-5 M) significantly impaired the viability of goat DPCs and lowered the ratio of proliferating cells. Otherwise, goat DPCs were stimulated to enter apoptosis and their cell cycle progression was severely blocked by ATRA. Moreover, the expression of fibroblast growth factor 7 (Fgf7), one of the potent hair growth stimulators secreted by DPCs, was transcriptionally repressed following ATRA treatment. Conclusion: DPCs are the targets of ATRA in the hair follicle, and ATRA negatively regulates hair growth by the targeted suppression of cell viability and growth factor expression of goat DPCs. Through these observations, we offer a new mechanistic insight into the roles of ATRA in hair biology.

Effect of miR-125b on dermal papilla cells of goat secondary hair follicle

Background: MicroRNAs (miRNAs) are endogenous noncoding RNAs that regulate various biological processes. miR-125b is a miRNA that has been reported to be critical for hair follicle (HF) morphogenesis and development. We identified that the expression of miR-125b varies during an individual hair cycle (anagen, catagen, and telogen) in the skin of cashmere goats. We constructed a gain model (by overexpressing miR-125b) and a loss model (by inhibiting endogenous miR-125b) based on dermal papilla cells (DPCs) to further investigate the role of miR-125b in HF cycle. In addition, we used a dual-luciferase system to highlight the predicated target genes of miR-125b. Results: We found that miR-125b affects the expression of FGF5, IGF-1, SHH, TNF-α, MSX2, LEF-1, FGF7, NOGGIN, BMP2, BMP4, TGF-ß1, and ß-catenin. The dual-luciferase assay further validated a direct interaction between miR-125b and FGF5 and TNF-α. Conclusion: miR-125b affects the expression levels of genes related to hair cycle and may also play a critical role in regulating the periodic development of HF.