Molecular characterization and expression profiles of two insulin-like growth factor 1 receptors during fasting and re-feeding in Siniperca chuatsi

Two distinct insulin-like growth factor 1 receptors of the mandarin fish Siniperca chuatsi (scIGF1R1 and scIGF1R2) were cloned and characterized in this study. The complementary DNA of scIGF1R1 [4254 base pairs (bp)] and scIGF1R2 (4248 bp) encoded 1418 and 1416 amino acids, respectively. Both receptors contained a single short transmembrane domain, two receptor L domains and a furin-like cysteine-rich domain. Phylogenetic analysis revealed that scIGF1R1 and scIGF1R2 were clustered in two different branches. Both receptors were expressed in all tissues tested, and the expression levels were relatively high in the gonad, liver and brain. During the first week of starvation, the expression levels of both receptors were increased in the muscle and liver, whereas hepatic scIGF1 expression was decreased. After re-feeding, the expression levels of both receptors were gradually restored to the pre-starvation levels in the liver and muscle. The concentration of serum scIGF1 did not exhibit regular changes compared with the control group during fasting and re-feeding. The varying expression profiles of the scIGF1Rs among tissues indicated that these receptors have distinct, tissue-specific roles. Furthermore, the changes in expression levels of scIGF1, scIGF1R1s during fasting and re-feeding provided evidence to support the link between nutritional status and gene expression related to growth and development.