盐度调控对花鲈(Lateolabrax maculatus)生长相关基因表达的影响

CLONING OF GROWTH HORMONE RECEPTOR AND SALINITY EFFECTS ON THE EXPRESSION OF ITS RELATED GENES IN SEABASS LATEOLABRAX MACULATUS

生长激素受体(GHR)作为GH/IGF轴的中心环节,在内分泌调控中发挥重要作用。本实验采用c DNA末端快速扩增法(RACE)技术克隆出花鲈GHR1和GHR2的c DNA全长序列。急性低盐度调控实验设为海水组、半海水组和淡水组。测定了急性低盐度调控24、48、96、144、192h后,花鲈肝脏中GHRs、IGF-1及垂体GH表达情况。结果表明,GHR1 c DNA全长序列2436bp,编码637个氨基酸;GHR2 c DNA全长序列2940bp,编码582个氨基酸。GHR1与GHR2由信号肽、胞外区、跨膜区、胞内区组成,且结构存在差异。脑、肾、鳃中GHR1表达明显高于GHR2;而在肌肉、垂体、肝脏、盲肠、胸腺、心脏中,GHR2表达明显高于GHR1。24h时,各组GHR1表达不变,GHR2、GH、IGF-1显著下降。之后,相对于海水组,淡水组和半海水组GHRs和IGF-1表达升高,而GH下降,GH与GHR负相关。据结果推测,花鲈GHR2可能为SL受体,GH/IGF轴参与低渗调控可能是通过增加GHRs,进而激活下游IGF-1表达而实现。

Growth hormone receptors(GHRs) as the key part of GH/IGF axis play important roles in individual endocrine. From the c DNA sequence of seabass Lateolabrax maculatus, two GHRs were cloned by rapid amplifycation of c DNA ends(RACE). Acute salinity regulation experiment contained three groups: seawater, half-seawater, and freshwater. Hepatic GHRs, insulin-like growth factor(IGF-1) and hypophyseal growth hormone(GH) were determined after 24 h, 48 h, 96 h, 144 h, 192 h by q PCR. GHR1 and GHR2 were 2436 bp and 2940 bp in length, encoding 637 and 582 amino acid, respectively. GHR1 and GHR2 contained different putative signal peptide, extracellular domain, transmembrane domain, and intracellular domain. Expression level of GHR1 was higher than GHR2's in brain, kidney and gill, but in muscle, pituitary, liver, caecum, thymus, and heart, the opposite. GHR1 m RNA was constant, while the levels of GHR2, GH, and IGF-1 decreased in 24 h. Compared with seawater group, the half-seawater and freshwater groups had higher expression of GHRs, IGF-1 and lower expression of GH. Therefore, the GHR1 of seabass is probably the somatolactin receptor. GH/IGF axis participates in osmoregulation, and may improve the levels of GHRs, and further activate the expression of IGF-1.