circKIF27 inhibits melanogenesis and proliferation by targeting miR-129-5p/TGIF2 pathway in goat melanocytes1

Skin and hair pigmentation in animals involve intricate regulatory processes. Circular RNA-microRNA (circRNA-miRNA) networks play vital roles in various biological processes, although their involvement in pigmentation has been underexplored. This study focused on circKIF27 expression, which differs significantly in melanocytes isolated from white and brown Boer coat-colored skin, yet its function remains unclear. Here, we investigated the roles of circKIF27 in melanocytes. In situ hybridization assays demonstrated that circKIF27 is expressed in the cytoplasm of melanocytes. qRT-PCR results revealed differential expression levels of circKIF27 in various tissues of male and female goats. Functional analysis showed that circKIF27 overexpression in melanocytes significantly reduces melanin production (P<0.01) and inhibits cell proliferation (P<0.0001). Bioinformatics analysis identified a putative miR-129-5p binding site on circKIF27, and luciferase reporter assays confirmed their interaction. Overexpression of miR-129-5p in melanocytes enhances melanin production (P<0.01) and promotes cell proliferation (P0.05). Further analysis revealed that TGIF2 possesses two potential miR-129-5p binding sites, and miR-129-5p overexpression in melanocytes significantly inhibits TGIF2 expression (P0.0001), suggesting a targeted regulatory relationship between these two molecules. Silencing TGIF2 expression via siRNA-TGIF2 transfection leads to increased melanocyte proliferation (P0.0001) and increased melanin production (P0.01). These findings highlight the involvement of the circRNA-miRNA network in pigmentation, offering new insights into the molecular mechanisms underlying pigmentation and guiding animal hair color breeding strategies.