The novel activities of the secreted AIMP1 for hair growth

Abstract

Hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs) are crucial for the biogenesis and maintenance of hair follicles (HFs). However, crosstalk between the two cells is not fully understood. Here, we found that a peptide derived from Aminoacyl-tRNA synthetase-Interacting Multi-functional Protein 1 (AIMP1) is secreted from HFSCs to activate DPCs for the maintenance of HFs. In vivo analysis revealed that the AIMP1 level was decreased in HFs with age and hair loss. The N-terminal 192-amino acid peptide fragment of AIMP1 is generated by matrix metalloproteinase 2 and secreted from the WNT-activated HFSCs to activate DPCs via fibroblast growth factor receptor 2. Deletion mapping revealed 41 amino acids (TN41, from Ala6 to Lys46) as the active region. This region activated the AKT and extracellular-signal-regulated kinase (ERK) pathway, increasing the level of beta-catenin and inducing the proliferation of DPCs. Taken together, the AIMP1 fragment secreted from HFSCs stimulates the hair cycle into active hair growth phases.