miR-148a-3p inhibits alpaca melanocyte pigmentation by targeting MITF

Abstract microRNAs (miRNAs) are well established as post-transcriptional regulators of gene expression, and function by binding regulatory regions, such as the 3′ untranslated region (UTR) of their target mRNA sequences. They have been implicated in the regulation of pigmentation, including the determination of alpaca hair-fiber color; however, the mechanisms underlying their effects are not yet well understood. Thus, the present study investigated whether the miRNA miR-148a-3p regulates the expression of the micropthalmia-associated transcription factor (MITF), since MITF is known to control the expression of key genes linked to coat color. The results of the conducted analyses showed that overexpressing miR-148a-3p in alpaca melanocytes caused the expression of MITF, pigmentation-associated protein tyrosinase (TYR), and both tyrosinase-related proteins 1 and 2 (TYRP1 and TYRP2, respectively) to be reduced, and thereby led to a decrease in the overall melanin content of the analyzed cells. Thus, the present study supports that miR-148a-3p is likely an important regulator of MITF expression.