Supersulfides regulate cell migration in human skin keratinocytes

As the outermost organ, the skin is particularly susceptible to physical damage. Keratinocytes are a major component of the epidermis, and their migration plays a crucial role in skin wound healing. Supersulfides contribute to energy production to sustain the life activities of organisms and are anticipated to play a role in various physiological functions; however, minimal studies have investigated their presence and functions in the skin. This study aimed to determine the presence of supersulfides in the skin and investigate their effect on keratinocyte migration. Using sulfane sulfur probe 4 (SSP4), a fluorescent probe that detects sulfane sulfur, the presence of supersulfides in both skin tissue and keratinocytes was revealed. Moreover, the primary supersulfide biosynthetic enzyme, cysteinyl-tRNA synthetase 2 (CARS2), was expressed at both the tissue and cellular levels. CARS2 expression and SSP4 fluorescence intensity in keratinocytes increased during wound healing, suggesting that supersulfide is involved in the regulation of cell migration. Knockdown of CARS2 suppressed keratinocyte migration and markedly downregulated gene expression of various chemokines. Protein expression analysis revealed that supersulfides regulate E-cadherin and matrix metalloproteinase (MMP)-9 via extracellular signal-regulated kinase (ERK) and protein kinase B (Akt). Furthermore, Na₂S₄ treatment of keratinocytes with CARS2 knockdown restored cell migration. We propose that supersulfide in the skin represents a novel mechanism of re-epithelialization and may serve as a therapeutic target for skin wounds.Key words: supersulfide, cysteinyl-tRNA synthetase 2, keratinocyte, cell migration, wound healing.