Nuclear receptors (NRs) belong to a large protein superfamily which includes intracellular receptors for secreted hydrophobic signal molecules, such as steroid hormones and thyroid hormones. They regulate development and reproduction in metazoans by binding to the promoter region of their target gene to activate or repress mRNA synthesis. Isolation and characterization of NRs in the parasitic trematode Schistosoma mansoni identified two homologues of mammalian thyroid receptor (TR). This was the first known protostome exhibiting TR homologues. Three novel NRs each possess a novel set of two DNA binding domains (DBD) in tandem with a ligand binding domain (LBD) (2DBD-NRs) isolated in Schistosoma mansoni revealed a novel NR modular structure: A/B-DBD-DBD-hinge-LBD. Full length cDNA of several NRs have been isolated and studied in the parasitic trematodes S. mansoni, S. japonicum and in the cestode Echinococcus multilocularis. The genome of the blood flukes S. mansoni, S. japonicum and S. haematobium, the liver fluke Clonorchis sinensis and the cestode Echinococcus multilocularis have been sequenced. Study of the NR complement in parasitic Platyhelminths will help us to understand the role of NRs in regulation of their development and understand the evolution of NR in animals.

核受体（NRs）属于大型蛋白质超家族，其中包括分泌的疏水信号分子（例如类固醇激素和甲状腺激素）的细胞内受体。它们通过与目标基因的启动子区域结合来调控后生动物的发育和繁殖，从而激活或抑制mRNA合成。寄生性吸虫曼氏血吸虫中NRs的分离和鉴定鉴定了哺乳动物甲状腺受体（TR）的两个同源物。这是第一个表现出TR同源物的已知蛋白质组。三个新颖的NR各自具有一组新颖的两个DNA结合结构域（DBD）以及在曼氏血吸虫中分离的配体结合结构域（LBD）（2DBD-NRs）揭示了一种新颖的NR模块化结构：A / B-DBD-DBD-hinge-LBD。几个卢比的全长cDNA已被分离，并在寄生吸虫研究曼氏血吸虫，日本血吸虫，并在绦虫棘球绦虫。血液中的基因组锚爪曼氏血吸虫，日本血吸虫和血吸虫，肝吸虫华支睾吸虫和绦虫的多房棘球已被测序。研究寄生虫蠕虫中的NR补体将有助于我们了解NR在调节其发育中的作用，并了解NR在动物体内的进化。