2. Academic Validation
  3. Characterization of serotonin receptors Aj5-HTR2 and Aj5-HTR7 reveals potential roles in circadian regulation of Apostichopus japonicus

Characterization of serotonin receptors Aj5-HTR2 and Aj5-HTR7 reveals potential roles in circadian regulation of Apostichopus japonicus

  • Gen Comp Endocrinol. 2026 Mar:379:114913. doi: 10.1016/j.ygcen.2026.114913.
Yibo Wang 1,  Yuting Liu 1,  Zhiqing Ye 1,  Lifei Ge 1,  Guanyu Han 1,  Jingjing Jiang 1,  Yuqian Chen 1,  Jixiu Wang 1,  Jieyang Weng 1,  Jingwen Yang 2,  Tianming Wang 3
Affiliations

Affiliations

  • 1 National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China.
  • 2 National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China. Electronic address: [email protected].
  • 3 National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, People's Republic of China. Electronic address: [email protected].
PMID: 41819218 DOI: 10.1016/j.ygcen.2026.114913
Abstract

Serotonin (5-hydroxytryptamine, 5-HT) is an evolutionarily conserved neurotransmitter that mediates neuroendocrine signaling through 5-hydroxytryptamine receptors (5-HTRs). In this study, two 5-HT Receptor subtypes, Aj5-HTR2 and Aj5-HTR7, were cloned and functionally characterized from the sea cucumber Apostichopus japonicus. Functional assays demonstrated that both receptors are signaling-competent molecules, exhibiting rapid receptor internalization upon 5-HT stimulation, along with dose-dependent increases in intracellular CA2+ or cyclic adenosine monophosphate (cAMP) levels and ERK1/2 phosphorylation. Quantitative Real-Time PCR showed that Aj5-HTR2 was highly expressed in the nerve ring and tentacles, whereas Aj5-HTR7 was highly expressed in the Polian vesicle and muscle. Moreover, both receptors exhibited distinct day-night expression rhythms, suggesting subtype-specific involvement in circadian neuroendocrine regulation. In summary, this work expands the repertoire of 5-HTRs in sea cucumbers and provides new insights into their potential roles in circadian neuroendocrine regulation.

Keywords

Apostichopus japonicus; Circadian rhythm; G protein-coupled receptor; Neuroendocrine regulation; Serotonin receptor.

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