MLPH Protein Boosts Human Hair Growth by Activating IGF-1 Signaling

Hair growth is a complex process involving various signaling pathways within the hair follicle, particularly the dermal papilla cells. The insulin-like growth factor-1 (IGF-1) signaling pathway is a known crucial regulator of hair shaft elongation and anagen induction (the active growth phase of hair). However, the precise molecular mechanisms by which specific proteins like MLPH influence this critical IGF-1 pathway to promote human hair growth remain underexplored.

The study found that MLPH significantly enhanced the proliferation of hDPCs by 35% compared to control cells (p<0.001). Treatment with recombinant MLPH led to a 2.5-fold increase in IGF-1 mRNA expression and a 1.8-fold increase in IGF-1R (IGF-1 receptor) protein levels in hDPCs, indicating robust activation of the IGF-1 pathway. These effects were mediated through the activation of downstream Akt and ERK signaling pathways, with MLPH treatment causing a 2-fold increase in p-Akt and p-ERK phosphorylation. Crucially, ex vivo human hair follicles treated with MLPH showed a remarkable average increase in hair shaft length of 0.3 mm per day, representing a 43% acceleration in growth compared to untreated controls over a 7-day period. Furthermore, MLPH knockdown using siRNA resulted in a 60% reduction in IGF-1 signaling activity and a 25% decrease in hDPC proliferation, confirming its direct involvement in hair growth regulation.