Abstract
Spexin (SPX), a novel neuropeptide discovered by the bioinformatics approach, has been shown to exert pleiotropic functions in mammals. However, little information regarding the physiological role of SPX is available in teleosts. As a first step, we cloned the spexin gene from a flatfish, the half-smooth tongue sole. The open reading frame (ORF) of tongue sole spexin contained 363 nucleotides encoding a 120 amino acid (aa) preprohormone with a calculated molecular mass and isoelectric point of 14.06 kDa and 5.86, respectively. The tongue sole SPX precursor contained a 27 aa signal peptide and a 14 aa mature peptide flanked by two dibasic protein cleavage sites (RR and GRR). Tissue distribution analysis showed that spexin mRNA could be detected in various tissues, notably in the brain. In addition, fasting stimulated the hypothalamic expression of spexin mRNA. Intraperitoneal injection of SPX increased gnih and gnrh3 mRNA levels in the hypothalamus; however, SPX inhibited the pituitary expression of gh, fshβ, and gthα mRNAs. Overall, our results reveal the existence of a functional SPX in the tongue sole, which could represent an important factor in the neuroendocrine control of flatfish reproduction and growth, and the spexin mRNA expression is regulated by feeding status.
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Acknowledgements
This work was supported by grants from the National Natural Science Foundation of China (31530078, 31730099, and 31602133), AoShan Talents Cultivation Program supported by Qingdao National Laboratory for Marine Science and Technology (No. 2017ASTCP-OS15), Taishan Scholar Climbing Project of Shandong, and the China Agriculture Research System (CARS-47).
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Highlights
• Identification for the first time in Pleuronectiformes of the spexin gene.
• spexin mRNA was ubiquitously expressed and most abundant in the brain.
• Fasting stimulated the hypothalamic expression of spexin mRNA.
• Spexin increased gnih and gnrh3 mRNA levels in the hypothalamus.
• Spexin inhibited the pituitary expression of gh, gthα, and fshβ mRNAs.
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Wang, S., Wang, B. & Chen, S. Spexin in the half-smooth tongue sole (Cynoglossus semilaevis): molecular cloning, expression profiles, and physiological effects. Fish Physiol Biochem 44, 829–839 (2018). https://doi.org/10.1007/s10695-018-0472-6
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DOI: https://doi.org/10.1007/s10695-018-0472-6