凡纳滨对虾ATF-2分子克隆及表达特征分析

Molecular cloning and expression analysis of ATF-2 from the shrimp Litopenaeus vannamei

激活转录因子-2(ATF-2)作为细胞内应激活化蛋白激酶下游效应分子,参与调控了生物体诸如细胞增殖、凋亡以及免疫炎症反应等许多细胞生物学过程.本研究首次从凡纳滨对虾(Litopenaeus vannamei)中克隆得到了ATF-2基因全长编码序列,命名为Lv ATF-2.序列分析表明,Lv ATF-2基因开放阅读框长1 719 bp,可编码572个氨基酸.其编码的蛋白具有特征性的锌指结构和碱性亮氨酸拉链结构域,并且在N端具有两个保守的苏氨酸磷酸化位点(Thr71和Thr73).进一步的系统进化树分析显示,Lv ATF-2蛋白与脊椎动物及软体动物ATF-2蛋白聚为一簇,且与软体动物ATF-2蛋白亲缘关系更近.半定量RT-PCR结果显示,Lv ATF-2基因在所检测的各个组织中均有转录,但在鳃和肠道中转录量较高.此外Lv ATF-2基因在白斑综合症病毒(WSSV)感染早期转录水平显著下降,提示该基因与WSSV感染密切相关,可能参与了对虾应答病毒的免疫反应过程.本文通对Lv ATF-2基因的克隆与表达特征分析,为将来研究该基因在对虾免疫应答过程中的功能提供了依据.

ATF-2,as a downstream effector of cellular stress-activated protein kinases,participates in the regulation of numerous cell processes,including cell proliferation and differentiation,cell cycle,apoptosis and immune inflammatory response. In the present study,a ATF-2 gene from Litopenaeus vannmei was cloned for the first time and designated as Lv ATF-2. Sequence analysis showed that the open reading frame of Lv ATF-2 gene was 1 719 bp in length and encoded a protein with 572 amino acids. The Lv ATF-2 protein contained characteristic zinc finger and b ZIP domains,and two conserved threonine phosphorylation sites（ Thr71 and Thr73） at the N-terminus. Phylogenetic tree analysis further displayed that Lv ATF-2 protein was clustered with vertebrate and mollusc ATF-2 protein and showed a closer relationship with ATF-2 protein of the mollusc. Semi-quantitative RT-PCR showed that Lv ATF-2 mRNAs were transcribed in all examined tissues,but the mRNA level of Lv ATF-2 gene was relatively higher in intestine and gill tissues. In addition,the transcriptional level of Lv ATF-2 gene was remarkably down-regulated during the early stage of WSSV infection,suggesting that Lv ATF-2 gene was closely related to WSSV infection and might be involved in immune response upon viral infection. Our study on Lv ATF-2 gene might have provided useful clue for exploring its function in shrimp immune response in future.