Abstract：
Contamination of aquatic environments has been steadily increasing due to human activities. The Pacific oyster Crassostrea gigas has been used as a key species in studies assessing the impacts of contaminants on human health and the aquatic biome. In this context, cytochrome P450 (CYPs) play a crucial role in xenobiotic metabolism. In vertebrates many of these CYPs are regulated by nuclear receptors (NRs) and little is known about the NRs role in C. gigas. Particularly, the CgNR5A represents a homologue of SF1 and LRH-1 found in vertebrates. Members of this group can regulate genes of CYPs involved in lipid/steroid metabolism, with their activity regulated by other NR, called as DAX-1, generating a NR complex on DNA response elements (REs). As C. gigas does not exhibit steroid biosynthesis pathways, CgNR5A may play other physiological roles. To clarify this issue, we conducted an in silico investigation of the interaction between CgNR5A and DNA to identify potential C. gigas CYP target genes. Using molecular docking and dynamics simulations of the CgNR5A on DNA molecules, we identified a monomeric interaction with extended REs. This RE was found in the promoter region of 30 CYP genes and also the NR CgDAX. When the upstream regulatory region was analyzed, CYP2C39, CYP3A11, CYP4C21, CYP7A1, CYP17A1, and CYP27C1 were mapped as the main genes regulated by CgNR5A. These identified CYPs belong to families known for their involvement in xenobiotic and lipid/steroid metabolism. Furthermore, we reconstructed a trimeric complex, previously proposed for vertebrates, with CgNR5A:CgDAX and subjected it to molecular dynamics simulations analysis. Heterotrimeric complex remained stable during the simulations, suggesting that CgDAX may modulate CgNR5A transcriptional activity. This study provides insights into the potential physiological processes involving these NRs in the regulation of CYPs associated with xenobiotic and steroid/lipid metabolism.
摘要：
由于人类活动，水生环境的污染一直在稳步增加。太平洋牡蛎Crassostreagigas已被用作评估污染物对人类健康和水生生物群落影响的研究的关键物种。在这种情况下，细胞色素P450(CYPs)在外源性生物代谢中起着至关重要的作用。在脊椎动物中，许多这些CYP受核受体（NRs）调节，对NRs在C.gigas中的作用知之甚少。特别是,CgNR5A代表在脊椎动物中发现的SF1和LRH-1的同源物。这个群体的成员可以调节CYPs参与脂质/类固醇代谢的基因，它们的活性受其他NR调节，称为DAX-1，在DNA反应元件(RE)上产生NR复合物。由于C.gigas不表现出类固醇生物合成途径，CgNR5A可能发挥其他生理作用。为了澄清这个问题，我们对CgNR5A和DNA之间的相互作用进行了计算机模拟研究，以鉴定潜在的C.gigasCYP靶基因。利用CgNR5A在DNA分子上的分子对接和动力学模拟，我们确定了与扩展RE的单体相互作用。在30个CYP基因的启动子区域以及NRCgDAX中发现了该RE。当分析上游监管区域时，CYP2C39，CYP3A11，CYP4C21，CYP7A1，CYP17A1和CYP27C1被定位为受CgNR5A调控的主要基因。这些鉴定的CYP属于已知参与外源性生物和脂质/类固醇代谢的家族。此外，我们重建了一个三聚体复合体，先前提出的脊椎动物，用CgNR5A：CgDAX进行分子动力学模拟分析。异三聚体复合物在模拟过程中保持稳定，表明CgDAX可能调节CgNR5A的转录活性。这项研究提供了有关这些NRs在调节与外源性生物和类固醇/脂质代谢相关的CYPs中的潜在生理过程的见解。
