Juglone ameliorates skin wound healing by promoting skin cell migration through Rac1/Cdc42/PAK pathway

Skin cell regeneration and wound healing are key processes in the recovery from skin injuries. Rapid cell migration and regeneration of skin cells lead to faster and better healing of wounded skin. In the present study, we aimed to investigate the wound healing potential of juglone, a naturally occurring Pin1 inhibitor found in walnuts. Cultured skin cells (NHDF and HaCaT) and hairless mice were treated with juglone after wound creation to examine its effects on cell migration and wound healing rate. The expressions of cell migration related proteins (Rac1, Cdc42, and α-PAK), collagen deposition, and angiogenesis were analyzed. Juglone treatment resulted in faster rate of growth and migration and recovered cell morphology, particularly at a concentration of 5 µM, in skin cells compared to the untreated group. In vivo experiments showed that mice treated with juglone showed faster wound healing rate with better skin morphology and collagen deposition than the vehicle group. Furthermore, juglone increased the activation and/or expression of Cdc42, Rac1, and α-pak in HaCaT cells, and resulted in enhanced angiogenesis in endothelial cells (HUVECs). Juglone also activated MAPKs signaling by activation of ERK, JNK, and p38 proteins. Taken together, these data suggest that juglone may be a potential candidate for wound healing and skin regeneration which ameliorates wound healing mainly by promoting skin cell migration through Rac1/Cdc42/PAK pathway.