Deciphering scavenger receptors reveals key regulators in the intestine that function in carotenoid coloration of leopard coral groupers (Plectropomus leopardus).

Carotenoid based body coloration are common features in fish, which depends on the diet derived carotenoids pigments deposition, employing a bunch of carotenoid uptake, absorption and processing related genes. Scavenger receptors are a large family of cell surface receptors with complex structure and diverse functions. However, the SRs genes have been insufficiently explored concerning their role in fish carotenoid coloration. Here, we systemically identified 19 SRs family genes and investigated their expression patterns of in various tissues of P. leopardus. Expression analysis unveiled the diverse involvements of SRs in the intestine of P. leopardus with different body colors and the responses to exogenous carotenoids. Notably, cd36, emerged as a pivotal factor in intestinal functions predominantly localized in the intestinal epithelial and goblet cells. Knockdown of cd36 led to the reduction in skin brightness and carotenoid levels in both intestine and skin, while overexpressing cd36 increased the carotenoids uptake of cells in vitro. Additionally, our investigations revealed that cd36 exerts regulation on genes associated with carotenoid uptake, transport, and processing. To sum up, our results provide a comprehensive view on SRs functions in carotenoid coloration of P. leopardus and will facilitate the understanding on the mechanism of carotenoids coloration of vertebrates.