Qian Zhaoying, He Shulin, Liu Tao, Liu Yongjie, Hou Fujun, Liu Qiao, Wang Xianzong, Mi Xiao, Wang Ping, Liu Xiaolin
College of Animal Science and Technology, Northwest A & F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Shaanxi Yangling 712100, China.
Nanjiang Marine Biotechnology Company Limited, Sanya, Hainan 572000, China.
Comp Biochem Physiol A Mol Integr Physiol. 2014 Jun;172:10-30. doi: 10.1016/j.cbpa.2014.02.011. Epub 2014 Feb 17.
Ecdysteroids initiate signaling along multiple pathways that regulate various aspects of development, maturation, and reproduction in arthropods. This study was carried out to seek the late target genes of ecdysteroid signaling from different tissues of the Pacific white shrimp, Litopenaeus vannamei. In the present study, eight isoforms of ecdysteroid receptor (EcR), two isoforms of retinoic acid X receptor (RXR), and one homolog of E75 were characterized from L. vannamei. The overall protein sequences and specific functional sites of EcR, RXR and E75 among crustacean species were found highly conserved. Tissue-specific, development stage-specific, and molt stage-specific expression patterns of LvEcR, LvRXR, and LvE75 were detected by qPCR. Double stranded RNA (dsRNA)-mediated RNA interference (RNAi) of any one of the three genes LvEcR, LvRXR and LvE75 caused specific expression changes of the other two, and resulted in corresponding expression changes of two molting related genes Cathepsin-L (LvCHSL) and Hemocyanin (LvHCyn) in the hepatopancreas, two chitin metabolism related genes chitin synthase (LvChS) and chitinase isoenzyme (LvChi2) in the epidermis, and two muscle growth related genes LvActin and myosin heavy chain (LvMHC) in the muscle. In correspondence, after in vivo injections of 20 hydroxyecdysone, specific expression changes of LvEcR, LvRXR, LvE75, LvCHSL and LvHCyn in the hepatopancreas, LvEcR, LvRXR, LvE75, LvChS and LvChi2 in the epidermis, and LvEcR, LvRXR, LvE75, LvActin and LvMHC in the muscle were also observed, respectively. Results in our study indicate multiple functions of ecdysteroids signaling in L. vannamei and the function may be time- and space-specific; ecdysteroids may act through different pathways via its functional receptor heterodimer EcR-RXR and the early responsive gene E75 to perform specific regulation roles on the target genes in different shrimp tissues; LvCHSL and LvHCyn in the hepatopancreas, LvChS and LvChi2 in the epidermis, and LvActin and LvMHC in the muscle are potential targets for ecdysteroid control. This is the first report on nuclear receptors in the economically important shrimp L. vannamei.
蜕皮类固醇沿着多条途径启动信号传导，这些途径调节节肢动物发育、成熟和繁殖的各个方面。本研究旨在从凡纳滨对虾不同组织中寻找蜕皮类固醇信号传导的晚期靶基因。在本研究中，从凡纳滨对虾中鉴定出了八种蜕皮类固醇受体（EcR）同工型、两种维甲酸X受体（RXR）同工型和一种E75同源物。发现甲壳类动物物种中EcR、RXR和E75的整体蛋白质序列和特定功能位点高度保守。通过qPCR检测了凡纳滨对虾EcR（LvEcR）、RXR（LvRXR）和E75（LvE75）的组织特异性、发育阶段特异性和蜕皮阶段特异性表达模式。对LvEcR、LvRXR和LvE75这三个基因中的任何一个进行双链RNA（dsRNA）介导的RNA干扰（RNAi），都会导致另外两个基因的特异性表达变化，并导致肝胰腺中两个与蜕皮相关的基因组织蛋白酶-L（LvCHSL）和血蓝蛋白（LvHCyn）、表皮中两个与几丁质代谢相关的基因几丁质合酶（LvChS）和几丁质酶同工酶（LvChi2）以及肌肉中两个与肌肉生长相关的基因Lv肌动蛋白和肌球蛋白重链（LvMHC）发生相应的表达变化。相应地，在体内注射20-羟基蜕皮酮后，还分别观察到肝胰腺中LvEcR、LvRXR、LvE75、LvCHSL和LvHCyn、表皮中LvEcR、LvRXR、LvE75、LvChS和LvChi2以及肌肉中LvEcR、LvRXR、LvE75、LvActin和LvMHC的特异性表达变化。我们的研究结果表明，蜕皮类固醇信号传导在凡纳滨对虾中具有多种功能，且该功能可能具有时间和空间特异性；蜕皮类固醇可能通过其功能性受体异二聚体EcR-RXR和早期反应基因E75通过不同途径对不同对虾组织中的靶基因发挥特定的调控作用；肝胰腺中的LvCHSL和LvHCyn、表皮中的LvChS和LvChi2以及肌肉中的LvActin和LvMHC是蜕皮类固醇调控的潜在靶标。这是关于经济重要性对虾凡纳滨对虾核受体研究的首次报道。
