Niche formed by bone morphogenetic protein antagonists gremlin 1 and gremlin 2 in human hair follicles

This study investigated the role of bone morphogenetic protein (BMP) antagonists, gremlin 1 (GREM1) and gremlin 2 (GREM2), in the regulation of hair follicle (HF) cycling. The research focused on the localization of these proteins in the hair bulb, particularly in the dermal sheath cup (DSC), which is known for its hair-inductive potential. The study found that GREM2 was robustly expressed in the DSC during various hair cycle phases, suggesting its role in modulating BMP signaling. GREM1 was also present in the DSC and epithelial matrix, indicating a potential direct role in hair growth. The balance between BMPs and their antagonists, such as GREM1 and GREM2, appeared crucial for maintaining normal hair cycling. The study involved skin samples from a 37-year-old female donor with female pattern baldness and confirmed findings across multiple hair follicles from different donors.