miR-182-5p affects melanin formation in Crassostrea gigas by regulating the MITF gene

MicroRNAs (miRNAs) contribute to diverse biological functions and physiological mechanisms through the intricate regulation of their target genes. In this study, we investigated the influence of miR-182-5p on pigmentation in Crassostrea gigas. Differentially expressed miR-182-5p associated with melanin formation was successfully screened using small RNA sequencing. qRT-PCR revealed a higher expression level of miR-182-5p in the white mantle and lower expression in hemocytes and the black mantle across diverse tissues of C. gigas. Target prediction analyses identified microphthalmia-associated transcription factor (MITF) as a potential target of miR-182-5p. The relationship between MITF and miR-182-5p was further verified via the overexpression and inhibition of miRNAs, as well as by a dual-luciferase reporter assay. Masson-Fontana melanin staining revealed a marked decrease in pigment granules after injections of miR-182-5p mimics. Western blotting analyses revealed that changes in miR-182-5p levels could regulate MITF protein expression. Upon miR-182-5p overexpression, genes associated with melanin synthesis were markedly downregulated in the mantle tissue. In summary, miR-182-5p participates in the regulation of melanin formation in C. gigas through the regulation of MITF. These results are significant for elucidating the regulatory role of miRNAs in mollusk melanin synthesis and promoting comprehension of the molecular mechanisms underlying mollusk melanin formation.