State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China.
Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao Marine Science and Technology Center, Qingdao, 266237, China.
Fish Physiol Biochem. 2024 Dec;50(6):2453-2474. doi: 10.1007/s10695-024-01394-7. Epub 2024 Aug 29.
Spexin (SPX1) is a neuropeptide of 14 amino acids (aa), originally identified by bioinformatics, which has been implicated in various physiological functions in vertebrates via galanin receptors 2 and 3 (GALR2/3). To clarify the biological role of SPX1 in the control of reproduction in yellowtail kingfish, which is regarded as a promising species for offshore aquaculture worldwide, cDNA sequences of spx1 and six potential receptors were identified in the current study. The open reading frame of yellowtail kingfish spx1 was 363 nucleotides in size that encoded a 120-aa preprohormone, and its mature peptide was highly conserved among other species. The cDNA sequences of six GALRs (galr1a, galr1b, galr2a, galr2b, galr type 1, and galr type 2) were 1053 base pairs (bp), 1068 bp, 981 bp, 1137 bp, 1038 bp, 924 bp, which encoded G protein-coupled receptors of 350 aa, 355 aa, 326 aa, 378 aa, 345 aa, 307 aa, respectively. Tissue distribution analysis showed that spx1, galr1b, and galr2b transcripts were mainly detected in the brain. The highest mRNA levels of galr1a and galr2a were observed in the pituitary, followed by the brain and ovary. Both galr type 1 and galr type 2 were widely expressed in various tissues, with a peak level in the kidney. Moreover, all spx1 and galr genes significantly fluctuated during early ontogeny, exhibiting different expression patterns. Intraperitoneal injection of SPX1 significantly increased brain gnrh1, gnih, spx1, gal, and tac3 expression, while it inhibited gnrh2, kiss1r, and kiss2r mRNA levels. In the pituitary, SPX1 injection reduced transcript levels of gh, lhβ, and fshβ. Overall, our results have revealed the involvement of SPX1 in the reproductive functions in yellowtail kingfish.
Spexin (SPX1) 是一种由 14 个氨基酸组成的神经肽（aa），最初通过生物信息学鉴定，通过甘丙肽受体 2 和 3 (GALR2/3) 参与脊椎动物的各种生理功能。为了阐明 SPX1 在控制黄鳍金枪鱼繁殖中的生物学作用，黄鳍金枪鱼被认为是全球有前途的海水养殖物种，本研究鉴定了 spx1 和六个潜在受体的 cDNA 序列。黄鳍金枪鱼 spx1 的开放阅读框大小为 363 个核苷酸，编码一个 120-aa 前激素原，其成熟肽在其他物种中高度保守。六个 GALRs（galr1a、galr1b、galr2a、galr2b、galr 1 型和 galr 2 型）的 cDNA 序列分别为 1053 个碱基对（bp）、1068 bp、981 bp、1137 bp、1038 bp、924 bp，分别编码 350 aa、355 aa、326 aa、378 aa、345 aa、307 aa 的 G 蛋白偶联受体。组织分布分析表明，spx1、galr1b 和 galr2b 转录本主要在脑中检测到。galr1a 和 galr2a 的 mRNA 水平最高在垂体中观察到，其次是脑和卵巢。galr 1 型和 galr 2 型在各种组织中广泛表达，在肾脏中达到峰值。此外，所有 spx1 和 galr 基因在早期发育过程中均显著波动，表现出不同的表达模式。腹腔注射 SPX1 显著增加了脑中 gnrh1、gnih、spx1、gal 和 tac3 的表达，同时抑制了 gnrh2、kiss1r 和 kiss2r 的 mRNA 水平。在垂体中，SPX1 注射降低了 gh、lhβ 和 fshβ 的转录水平。总之，我们的研究结果表明 SPX1 参与了黄鳍金枪鱼的生殖功能。
