ABSTRACT
Although many microRNAs (miRNAs) are known to function as regulators of coat color and melanogenesis, the underlying molecular mechanisms of miR-100-5p governing melanogenesis were not completely known.The goal of this study was to determine the effect of miR-l()()-5p on melanogenesis in alpaca melanocytes.Fibroblast growth factor 21 (FGF21) is a predicted target gene of miR-100-5p and the luciferase reporter assay demonstrated that miR-100-5p regulates FGF21 by binding to its 3' untranslated region (3'UTR).In this study, alpaca melanocytes were transfected with miR-100-5p, inhibitor and negative control plasmid.Results showed that miR-100-5p overexpression significantly decreased mRNA and protein expression of FGF2\.Meanwhile, the ERK signal pathway was inhibited, with subsequent up-regulation of microphthalmia-associated transcription factor (MITF) , tyrosinase (TYR) and tyrosinase-related protein 2 (TYRP2), which increased melanin production.The results suggest that miR-100-5p may regulate melanogenesis by targeting FGF21 via extracellular regulated MAP kinase (ERK) signaling pathway.
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.