Abstract

Kisspeptin is a conserved neuropeptide that regulates reproductive function and other physiological processes across vertebrates via its cognate G protein-coupled receptors (GPCRs), commonly referred to as kisspeptin receptors (KissRs). In teleosts, extensive gene duplication and lineage-specific diversification have generated multiple kisspeptin ligands and receptors, yet the molecular properties and signaling profiles of individual KissRs remain incompletely characterized. Here, we identified and cloned a Kissr3-type receptor from the large yellow croaker ( Larimichthys crocea ), designated Lc Kissr 3 . Sequence and phylogenetic analyses classified Lc Kissr3 within the teleost Kissr3 clade. Functional assays in a human embryonic kidney cell line (HEK293) demonstrated that stimulation with synthetic kisspeptin-2 decapeptide ( Lc Kiss2-10) activated multiple downstream signaling pathways, including intracellular calcium ions (Ca 2+ ) mobilization, cyclic adenosine monophosphate (cAMP) accumulation, and mitogen-activated protein kinase /extracellular signal-regulated kinase (MAPK/ERK) phosphorylation, in a concentration-dependent manner. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis further showed that lckissr3 is expressed in multiple tissues, with the highest levels detected in the pituitary and testis. Together, these findings establish Lc Kissr3 as a functional kisspeptin receptor and provide a molecular basis for further investigation of kisspeptin signaling in teleost physiology.