Expression of Retinoid Nuclear Receptor Superfamily Members in Human Hair Follicles and Its Implication in Hair Growth

The study investigated the expression of retinoid nuclear receptor superfamily members in human hair follicles and their impact on hair growth. It was found that the cellular/cytoplasmic retinoic acid binding protein-II and retinoid-X-receptor-alpha were consistently and strongly expressed in both dermal and epithelial compartments, similar to the vitamin D receptor. In contrast, RAR alpha and RAR gamma were not consistently expressed in dermal papilla cells, while RAR beta was always present. In dermal sheath fibroblasts, RAR alpha, RAR beta, and RAR gamma mRNAs were moderately expressed, but RAR beta was absent in the epithelial compartment. The study also revealed that RAR agonists, such as all-trans RA and CD367, inhibited hair follicle survival in vitro, whereas the RXR agonist CD2425 stimulated hair growth and survival, comparable to 1 alpha,25-dihydroxyvitamin D3. This suggested that RXR agonists could potentially stimulate hair growth in humans.