达氏鲟2种胰岛素样生长因子的克隆及其对饥饿胁迫的响应

Molecular Cloning of Insulin-like Growth Factor 1, 2 in Acipenser dabryanus and Their Expression Level During Starvation Stress

【目的】胰岛素样生长因子(IGF)是一类在细胞增殖与分化、免疫及个体生长发育中具有重要作用的调控因子。因此,对IGF表达特征的分析有利于揭示其在鱼类生长及营养调控等过程中的功能。【方法】本研究以达氏鲟转录组测序获得的unigene序列为基础,获得了胰岛素生长因子-1(IGF-1)和胰岛素生长因子-2(IGF-2)的cDNA全序列,并分析了IGF-1和IGF-2基因在各组织及饥饿胁迫下的表达情况。【结果】达氏鲟IGF-1全长为2262 bp,其中5′非编译区为292 bp,3′非编译区为1841 bp,开放阅读框(ORF)为489 bp,共编码163个氨基酸;IGF-2的全长为1821 bp,其中5′非编译区为109 bp,3′非编译区为1052 bp,开放阅读框为660 bp,编码220个氨基酸。达氏鲟IGF氨基酸序列与其他鲟鱼类具有较高的同源性。IGF-1和IGF-2在达氏鲟各组织中广泛分布,IGF-1在眼睛中的表达量最高,而IGF-2在肝脏和性腺中的表达量最高。饥饿条件下,肝脏、肠道和肌肉中的IGF-1表达量呈先上升后降低的趋势。【结论】与饥饿第0天相比,饥饿14 d后各组织中的IGF-1表达量显著性降低(P<0.05),表明IGF-1的表达与达氏鲟的营养状况密切相关。而IGF-2在饥饿14 d后的表达量与第0天相比无显著性差异(P>0.05),提示着达氏鲟IGF-2和IGF-1的功能可能存在一定的差异。

【Objective】Insulin-like growth factor system(IGFs) are a group of regulating factors that play an important part in the proliferation and differentiation of cells, immunity and development of the skeletal muscle. Therefore, the analysis of IGF expression is conducive to revealing its functions in the process of fish growth and nutritional regulation.【Method】In this study, we obtained the full length cDNA of IGF-1 and IGF-2 from the unigene database by transcriptome sequencing of Acipenser dabryanus. The tissue distribution and expression level during starvation stress were also analyzed. 【Result】The full length of IGF-1 was 2262 bp which contained 292 bp 5′ untranslated region(UTR), 1841 bp 3′ UTR and 489 bp open reading frame(ORF). The ORF of IGF-1 encoded 163-residue peptide. The full length of IGF-2 was 1821 bp which contained 109 bp 5′UTR, 1052 bp 3′ UTR and 660 bp ORF. The ORF of IGF-2 encoded 220-residue peptide. Phylogenetic analysis showed that the IGF-1 and IGF-2 clustered with other species in genus Acipenser. Tissue expression analysis showed that IGF-1 and IGF-2 were widely expressed in different tissues, and IGF-1 was highly expressed in eye while IGF-2 was mostly detected in liver and gonad. During starvation, the expression level of IGF-1 was increased firstly and then decreased significantly in liver, gut and muscle.【Conclusion】The expression level of IGF-1 was decreased significantly during fasting for 14 days compared to the initial value in all the examed tissues(P<0.05), indicating a positive correlation between nutritional status and IGF-1 mRNA level. Whereas, the expression level of IGF-2 was decreased slightly with no significant change detected(P>0.05) during fasting for 14 days compared to the initial value, inferring a diverse function of IGF-1 and IGF-2 in A. dabryanus.