ABSTRACT
Dickkopf-3 (DKK3) , as a critical inhibitor of the Wnt/p-catenin signaling pathway, may he involved in melanogenesis.In the current study, we investigated the effects of DKK3 on melanogenesis in melanocytes of alpaca.Overexpression of DKK3 in alpaca melanocytes, the expression of Wntl, Lefl , Myc and the major target genes termed microphthalmia-associated transcription factor (M1TF) and its downstream genes, including tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1) and tyrosinase- related protein 2 (TYRP2) were significantly decreased at both mRNA and protein levels (P<0.05); total alkali melanin, pheomelanin and eumelanin were decreased by 80.30%, 72.17% and 64.60% (P <0.05), respectively.In contrast, in the melanocytes transfected with siRNA-DKK3 (a small interference RNA targeting DKK3) , the expression of Wntl, Lefl, Myc, MITF, TYR, TYRPl and TYRP2 were significantly increased at both mRNA and protein levels (P<0.05) ; total alkali melanin, pheomelanin and eumelanin were significantly increased by 1.65 folds, 1.25 folds and 1.21 folds (P< 0.05) , respectively.These results indicate that DKK3 regulates melanogenesis in alpaca melanocytes via the Wnt/p-catenin signaling pathway and down-regulates MITF.