MiR-382 Functions on the Regulation of Melanogenesis via Targeting dct in Rainbow Trout (Oncorhynchus mykiss).

MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs that are involved in a diverse collection of biological processes as important post-transcriptional regulators. However, little is known about the molecular regulatory mechanism of miRNAs in fish skin pigmentation. In this study, we first confirmed that dopachrome tautomerase (dct), a key gene of melanogenesis, is a target of miR-382 in rainbow trout (Oncorhynchus mykiss) using luciferase reporter assay. The analysis of different developmental stages and tissue expression patterns between wild-type and yellow mutant rainbow trout suggested that miR-382 is a potential regulator during the process of skin pigmentation. In vitro, miR-382 mimics in rainbow trout primary liver cells significantly downregulated dct expression and resulted in decreased expression of key melanogenic genes including tyrosine-related protein 1 (tyrp1) and premelanosome protein (pmel), whereas the expression level of dct was markedly increased after transfected with miR-382 inhibitor. In vivo, overexpression of miR-382 by injection of miR-382 agomir significantly depressed the expression of dct in dorsal skin, tail fin, and liver and then reduced the expression levels of tyrp1 and pmel. Furthermore, transfection of miR-382 mimics inhibited cell proliferation and induced apoptosis. Taken together, our results identified a functional role of miR-382 in rainbow trout skin pigmentation through targeting dct, which facilitate understanding the regulatory mechanism of rainbow trout skin color at the post-transcriptional level and provide a theoretical basis for molecular breeding with skin color as the target trait.