Inhibition of microRNA-139-5p Improves Fibroblasts Viability and Enhances Wound Repair in Diabetic Rats Through AP-1 (c-Fos/c-Jun).

Introductions: Diabetic foot ulcers (DFU) are notoriously difficult to heal, however, its underlying molecular mechanisms are unknown. MicroRNA-139-5p participates in various biological processes, including cancer and vascular endothelial injury, while its role in diabetic wound healing has not been reported. Methods: Sprague-Dawley (SD) rats were intraperitoneally injected with streptozotocin and a 1.0 cm full-layer dorsal skin wound was made to establish a diabetic wound model. On days 1, 4, 7, and 10 after the wound was made, a solution containing microRNA-139-5p antagomir or control was injected along the dorsal edge of the wound. Wound healing was analyzed using Image J, histological analysis and molecular analysis. Skin tissues from 4 diabetic and 4 matched non-diabetic ulcer patients were obtained to detect microRNA-139-5p expression. In vitro, human skin fibroblasts were transfected with microRNA-139-5p inhibitors/mimics, the function of the fibroblasts was evaluated by CCK-8 assay and scratch assay, and AP-1 (c-Fos/c-Jun) was detected. Results: Obviously elevated microRNA-139-5p expression was detected in the wound tissue of the rats with diabetes and patients with DFUs, and the microRNA-139-5p antagonist-treated diabetic wounds had faster healing rates. The pace of diabetic wound re-epithelialization and angiogenesis was accelerated, and the expression of AP-1 family members (c-Fos/c-Jun), and VEGF, PDGF was upregulated in the wound tissue of diabetic rats treated with topical microRNA-139-5p antagomir. In vitro, the expression of microRNA-139-5p was up-regulated in human skin fibroblasts induced by high glucose treatment, while the function of the cell proliferation and migration was promoted and the level of AP-1 (c-Fos/c-Jun) was increased after transfected with the microRNA-139-5p inhibitor, and vice versa. Our study further verified that microRNA-139-5p regulated the migration of human skin fibroblasts by modulating c-Fos. Conclusion: Inhibiting microRNA-139-5p improves fibroblasts viability and promotes diabetic wound healing, suggesting that this may be a therapeutic strategy for diabetic foot ulcer.