Abstract: Objective To explore the regulatory mechanism of the miR-486-5p/forkhead box transcription factor O subfamily 1 (FOXO1) axis on the proliferation and migration of keratinocytes during repair of deep second-degree burn wound. 
Methods A mouse model of deep second-degree burn was established, and the mice were randomly divided into 4 groups: NC mimic+Vector group, FOXO1 group, miR-486-5p mimic group and miR-486-5p mimic+FOXO1 group. The wound was treated with miR-486-5p mimic and/or FOXO1 to observe the wound healing. At different time points after burn, including hemostasis (0 h), inflammation (24 h), and proliferation (7th and 14th day), in situ hybridization and reverse transcription quantitative polymerase chain reaction (RT-qPCR) were used to detect miR-486-5p expression sites and levels in wound edge tissues, respectively. The expression of FOXO1 was detected by immunofluorescence staining. Luciferase reporter analysis confirmed the binding relationship between FOXO1 and miR-486-5p. The human HaCaTkeratinocytes(HaCaT) cell model of miR-486-5p overexpression or knockdown was constructed. The proliferation and migration of cells were investigated by EdU method and scratch test, and the expression of FOXO1 protein in cells was analyzed by Western blot. 
Results miR-486-5p was significantly up-regulated during the healing of deep second-degree burn wounds in mice. In vivo model showed that miR-486-5p promoted wound healing by inhibiting the expression of FOXO1. In HaCaT cells, miR-486-5p overexpression increased proliferation and migration of the cells, where as miR-486-5p inhibition had the reverse effect. FOXO1 was a direct target of miR-486-5p in keratinocytes. FOXO1 overexpression decreased the percentage of EdU positive cells and wound healing of HaCaT cells, and reversed the induction of EdU positive cells and wound healing by miR-486-5p. 
Conclusion MiR-486-5p is a crucial regulator in repair of deep second-degree burn wound that facilitates keratinocyte proliferation and migration by inhibiting the expression of FOXO1. 

Key words: burns, miR-486-5p, forkhead box transcription factor O subfamily 1