Expression of decorin throughout the murine hair follicle cycle: hair cycle dependence and anagen phase prolongation

Decorin is a prototypical member of the small leucine‐rich proteoglycan (SLRP) family, which is involved in numerous biological processes. The role of decorin, as a representative SLRP, in hair follicle morphogenesis has not been elucidated. We present our initial findings on decorin expression patterns during induced murine hair follicle (HF) cycles. It was found that decorin expression is exclusively restricted to the epidermis, outer root sheath and sebaceous glands during the anagen phase, which correlates with the upregulation of decorin mRNA and protein expression in depilated murine dorsal skin. Furthermore, we used a functional approach to investigate the effects of recombinant human decorin (rhDecorin) via cutaneous injection into HFs at various murine hair cycle stages. The local injection of rhDecorin (100 μg/ml) into the hypodermis of depilated C57BL/6 mice at anagen delayed catagen progression. In contrast, rhDecorin injection during the telogen phase caused the premature onset of anagen, as demonstrated by the assessment of the following parameters: (i) hair shaft length, (ii) follicular bulbar diameter, (iii) hair follicle cycling score and (iv) follicular phase percentage. Taken together, our results suggest that decorin may modulate follicular cycling and morphogenesis. In addition, this study also provides insight into the molecular control mechanisms governing hair follicular epithelial–mesenchymal interactions.