大菱鲆2种类胰岛素样生长因子结合蛋白基因克隆及在成鱼和早期发育期中的表达

Cloning of IGFBP-1,-2 and expression analysis during adult and early developmental stages in Scophthalmus maximus

类胰岛素样生长因子结合蛋白(IGFBP)在调节IGF的生物学功能上起着重要的作用,利用简并引物扩增及RACE克隆技术,首次克隆得到大菱鲆IGFBP-1,-2基因cDNA全长序列。两个基因氨基酸序列都分为保守的N端和C端以及高度特异的L区域3个部分,其中N端和C端共包含18个半胱氨酸残基,N端存在一段保守的(GCGCCXXC)结构,C端存在一段保守的(CWCV)结构,这些结构在与IGF相互作用以及调节与IGF结合的亲和性和稳定性起重要作用。组织表达分析表明,igfbp-1主要在肝脏及脾中大量表达,在其他组织中表达量较少,igfbp-2除在肌肉中没有检测到表达外,在其他组织中均有表达,其中肝脏脑、心、肾、肠中表达量较高。广泛的组织表达模式表明IGFBP是通过自分泌和旁分泌来调节IGF的功能。对于胚胎发育期表达分析表明,ig-fbp-1在整个发育期均检测到表达,igfbp-2在胚体期开始有表达,结果表明igfbp-1和igfbp-2在胚胎发育过程中的细胞生长以及组织器官分化都起着重要的生理学作用。

Insulin-like growth factor-binding proteins（IGFBPs） play a vital role in regulating the biological activities of IGFs.The full-length cDNA sequences of Scophthalmus maximus IGFBP-1,-2 were cloned and determined by degenerate primer PCR amplification and RACE cDNA amplification for the first time.Both amino acid sequences of IGFBPs can be divided into three domains,the conserved N-terminal domain,the C-terminal domain,and the variable central L-domain.The N-domain and C-domain contain 18 cysteine residues.A local motif（GCGCCXXC） is well conserved within the N-terminal domain and the conserved CWCV motif in C-domain.These motifs have an important role in the binding of IGFBPs to IGFs.Tissue expression analysis showed that igfbp-1 mRNA is highly expressed in liver and spleen,and lower in other tissues.igbfp-2 mRNA is widely expressed in all tissues except muscle.Strong amplification signals were detected in liver,brain,heart,kidney and intestine.This widely expressed pattern suggests that IGFBP has autocrine/paracrine actions on regulating IGFs.The expression analysis during embryonic and larval developmental stages showed that igfbp-1 mRNA could be detected during the whole developmental stages and igfbp-2 mRNA was first detected in the egg of embryoid stage.The mRNA expression suggests that igfbp-1,-2 may play important physiological roles in cell growth as well as in organ differentiation during the embryonic developmental stages.