Fig. 6

miR-181a-5p and miR-199a inhibited melanin synthesis and promoted melanosome degradation, respectively. The main miRNA contents were confirmed by RT-PCR in the exosomes obtained from hAMSCs (a). The expression levels of cellular miRNA were quantitated by RT-PCR, showing that miR-181a-5p and miR-199a were highly expressed in B16F10 cells treated with hAMSCs-derived exosomes (b). Melanin contents were measured after the transfection of the miR-181a-5p and miR-199a mimic or inhibitor into the B16F10 cells with or without α-MSH stimulation (c, d). The expression levels of the MITF, TRP2 and Tyr were measured by western blot analysis (e) and qRT-PCR (f), respectively. Dual-luciferase reporter assay showed that the relative luciferase activity which was normalized to Renilla luciferase activity was inhibited after the co-transfection of 293 T cells with the miR-181a-5p mimic and the activities were not affected by pmirGLO vector containing the WT or MUT MITF 3′-UTR (g). The LC3B and P62 were analyzed by western blot after the transfection of miR-199a mimic or inhibitor (h). Data are presented as mean ± SD. The experiments were repeated three times independently and the data of one representative experiment was shown. *p < 0.05; **p < 0.01, ***p < 0.001