The down-regulation of miR-141-3p inhibits red coloration through chromatophores apoptosis and aberrant pigmentation in koi carp (Cyprinus carpio L.)

In the teleost fish species, the miR-200 family has been identified as a group of multifunctional microRNAs across various species. However, their precise functions in the context of skin pigmentation remain to be fully elucidated. To investigate the role of the miR-200 family in color formation, we conducted a detailed examination of the spatio-temporal expression patterns of these microRNAs. By employing an antagomir targeting miR-141-3p in vivo, we were able to identify phenotypic alterations and assess the impact on coloration by analyzing genes involved in carotenoid biosynthesis and pigment cell differentiation. Our findings that the expression levels of all miR-200 family members were significantly higher in red tissue compared to white tissue, with miR-141-3p exhibiting strong expression in scales. Notably, the injection of an antagomir led to a marked suppression of miR-141-3p expression, which consequently resulted in a decrease in the density of xanthophores and erythrophores within the scales, thereby causing a lightening of color. Furthermore, through the analysis of mRNA and miRNA expression patterns, we were able to screen for color-related microRNAs, including scarb1, pax7a, pax7b, spra and sprb, among others. These results suggest that miR-141-3p may induce a reduction in pigment-related genes by upregulating apoptosis-related genes, thereby contributing to the lighter phenotypic expression observed in koi fish.