MicroRNA-5110 regulates pigmentation by cotargeting melanophilin and WNT family member 1

Abstract

Mammalian pigmentation requires the production of melanin by melanocytes and its transfer to neighboring keratinocytes. These complex processes are regulated by several molecular pathways. Melanophilin (MLPH) andWNT familymember 1 (WNT1), known to be involved inmelanin transfer andmelanin production, respectively, were predicted tobe targets ofmicroRNA-5110using bioinformatics. Inthecurrent study,we investigated theeffectsof microRNA-5110 on pigmentation in alpaca (Vicugna pacos)melanocytes. In situ hybridization identified high levels of microRNA-5110 in the cytoplasm of alpaca melanocytes. Luciferase activity assays confirmed that MLPH and WNT1 were targeted by microRNA-5110 in these cells. Overexpression and knockdown of microRNA-5110 in alpaca melanocytes downregulated and upregulated MLPH andWNT1 expression at themRNAand protein levels, respectively. In addition, overexpression and knockdown of microRNA-5110 in alpaca melanocytes decreased and increased, respectively, themRNAlevels of themelanin transfer-related genes, rat sarcoma (RAS)-associated binding (RAB27a) andmyosin5a (MYO5a); themRNAlevels ofmicrophthalmia-associated transcription factor (MITF), tyrosinase (TYR), and tyrosinase-related protein (TYRP)1; and the production of total alkali melanin and pheomelanin. In contrast, overexpression and knockdownof microRNA-5110 increased and decreased themRNAlevels of TYRP2, respectively. Overexpression of microRNA-5110 also increased eumelanin. These results indicate that microRNA-5110 regulates pigmentation in alpaca melanocytes by directly targeting MLPH and WNT1 to affect eumelanin production and transfer.