Figure 4.

Effects of miRNA-mediated tyrosinase (Tyr) gene silencing on the depigmentation of mouse skins and hairs. Targeted gene silencing in epidermal tissues was shown to be feasible using the ectopic transfection of a recombinant SpRNAi-RGFP gene vector expressing the native mir-434 pre-miRNA. Subcutaneous transfection of mir-434-5p induced a strong and specific gene silencing effect on Tyr but not house-keeping GAPDH expression, whereas transfection of a U6 promoter-driven siRNA against the same Tyr sequence resulted in nonspecific RNA degradation of both Tyr and GAPDH gene transcripts. Because Tyr plays an essential role in melanin (black pigment) production, a successful Tyr gene silencing effect can be manifested by the significant loss of black color in mouse skins and hairs. The circles indicate the location of i.c. injections. Small windows show the northern blotting of Tyr mRNA levels in local hair follicles, confirming the gene silencing effect of mir-434-5p on Tyr expression.