Lysine regulates TOR and NPY through taste receptor T1R1 in Chinese perch (Siniperca chuatsi)

Abstract

Chinese perch (Siniperca chuatsi), a typical carnivorous fish, has a high dietary protein requirement. The poor utilization of plant protein in carnivorous fish is well known, while the crucial mechanism has not been characterized. Lysine, generally the first limiting amino acid in plant-derived protein dietary feed, might play essential roles in regulating protein synthesis and feed intake. G protein-coupled taste receptor T1R1/T1R3 heterodimer as a direct sensor of extracellular amino acids (AA) availability via Ca2+ stimulation. In the present study, we identified the umami taste receptor genes and found that T1R1/T1R3 heterodimer could strongly respond to L-Lys in Chinese perch, and L-Lys could regulate the target of rapamycin (TOR) and Neuropeptide Y (NPY) through the taste receptor T1R1/T1R3 signaling pathway. The results suggested that lysine and its taste sensing system might be the essential targets when making efforts to replace fish meal with plant protein.