Genome-wide identification and expression analysis of fatty acid-binding proteins (FABPs) in Chinese perch Siniperca chuatsi and their circadian rhythm responses to cadmium exposure

Abstract

Fatty acid-binding proteins (FABPs) function as fatty acid chaperones, and they play a key role in lipid metabolism. The diversity of fabp gene family members is important for different fatty acid absorption and transport. In the present study, we identified 13 fabp genes from Chinese perch (Siniperca chuatsi). The spatiotemporal expression profiles of these 13 Sc-fabp genes, their circadian rhythm expression characteristics in intestine, and transcriptional regulation under cadmium exposure were investigated. Phylogenetic analysis indicated that the teleost-specific genome duplication event made a contribution to the expansion of Sc-fabp genes. The protein coding regions of all the 13 Sc-fabp genes were composed of 4 exons. These 13 genes exhibited similar protein length, but a low identity in protein sequences. The tissue expression profiles of most fabp genes in Chinese perch (Sc-fabp2a, Sc-fabp2b, Sc-fabp3, Sc-fabp6a, Sc-fabp7a, and Sc-fabp7b) were consistent with those of their orthologous genes in mammalian, but the Sc-fabp1, Sc-fabp6ba, and Sc-fabp6bb showed distinct tissue expression patterns from their orthologous genes in mammalian. The total expression level of Sc-fabps was increased with embryonic development, but it was decreased significantly after hatching. Sc-fabp1, Sc-fabp3, Sc-fabp11a, and Sc-fabp11b were the mainly expressed subtypes in embryonic development stages. Under natural conditions, the expression of these 4 subtypes Sc-fabp1, Sc-fabp2a, Sc-fabp2b, and Sc-fabp6a exhibited significant circadian rhythm in intestine, and their peak expression levels were observed from ZT 8.83 h to ZT 13.54 h. Cadmium exposure resulted in the up-regulation of fabp gene expression and the loss of circadian rhythm in Chinese perch intestine. Our results provide reference for further investigation of the biological functions of fabp gene subtypes in fish.