核受体间的相互作用在多溴联苯醚诱发神经毒性效应中的作用机制研究

Polybrominated diphenyl ether (PBDE) compounds are new emerging persistent organic pollutants that are extensively used as flame-retardants in the potentially flammable materials, such as electronic facilities, rubbers, plastics and textiles. PBDEs have the neurotoxicity and reproductive toxicity to animal and human, thus it has become a hot spot in the field of public health and environment science. Pregnane X Receptor (PXR) was induced significantly by PBDEs and involved in many other important cell nuclear receptors (NR) in the process. However, the potential underlying mechanisms through multi-nuclear receptors interaction in neurotoxicity induced by PBDEs are not well understood and haven’t been reported worldwide till now. Retinoid X Receptors (RXR) is a common binding partner or requisite heterodimer for a number of receptors, including PXR, TR, PPAR, CAR, and LXR, and is also capable of forming homodimers to mediate biological effect. In the present study, hRXR gene-silenced and hRXR gene-overexpression human neuroblastoma SK-N-SH cells systems were constructed and used to investigate the role and the mechanism of multi-nuclear receptors interaction in neurotoxicity induced by PBDEs. The cell cycle, oxidative damage and chromosome damage as well as DNA damage will be investigated in order to reveal the biology role of RXR receptor, moreover the spatial distribution, expression levels and spatial and temporal relationships in cells for the four important nuclear receptors including PXR, RXR, TR (Thyroid Receptors) and ER (Estrogen Receptor) will be also explored in order that interaction of the aforementioned four nuclear receptors can be clarified. The present study will highlight the mechanism of neurotoxicity and reproductive toxicity induced by PBDEs and provide siginificant scientific basis to elucidate the machanism of other biological toxic effect.

多溴联苯醚（Polybrominated Diphenyl Ethers, PBDEs）化合物是新型环境持久性有机污染物，广泛用于产品阻燃，对人类具有突出的神经内分泌毒性和生殖毒性，是环境健康领域新的研究热点。其通过激活细胞核受体孕烷受体（Pregnane X Receptor，PXR）发挥毒性效应，伴随多个重要核受体参与。视黄醛X受体（Retinoid X Receptors，RXR）是许多核受体激活的必需异源二聚体。多受体在PBDEs神经毒性效应中的作用机制研究国内外未见报道。本研究拟通过构建人神经母细胞瘤SK-N-SH的RXR基因缺陷细胞株和高表达细胞株，研究RXR受体在化学物毒性效应中的作用；探讨视黄醛X受体、甲状腺激素受体、雌激素受体和孕烷受体等多个重要核受体相互作用和时空联系，初步阐明多受体相互作用在PBDEs诱导神经毒性效应的作用机制，最终为阐明其它毒性效应机制提供科学依据。

多溴联苯醚（Polybrominated Diphenyl Ethers, PBDEs）化合物是新型环境持久性有机污染物，广泛用于产品阻燃，对人类具有神经内分泌毒性和生殖毒性，是环境健康领域新的研究热点。本研究聚焦于人体分布最高的代表性单体BDE47，开展了以视黄醛X受体（Retinoid X Receptors，RXR）为核心的甲状腺激素受体（TRs）、雌激素受体（ERs）、过氧化物酶体增殖物激活受体（PPARs）和孕烷受体（PXR）等多个重要细胞核受体间相互作用在多溴联苯醚诱发神经毒性效应中的作用机制研究。项目成功构建了人神经母细胞瘤SK-N-SH细胞的RXRA基因缺陷细胞和RXRA基因过表达细胞，为RXRA基因调控的分子通路相关研究提供了重要受试材料和研究手段。采用该细胞株，进一步系统开展了多溴联苯醚诱导神经毒性效应的机制研究。结果表明，BDE-47诱导了细胞氧化损伤，改变细胞周期时相，将细胞周期阻滞在S期，具有时间-剂量-效应关系；并通过扰动细胞内神经递质类、氧化应激和核苷酸代谢相关分子通路，从而抑制细胞增殖，发挥其神经毒性效应。研究还表明RXRα受体在提高细胞对抗氧化应激损伤中发挥重要作用。BDE-47通过重要细胞核受体介导毒性效应的研究表明，BDE-47可影响细胞内包括RXRα受体在内的多个重要核受体的表达，诱导其表达增高，扰乱核受体结合的平衡，干扰RXRα与其他异源核受体形成二聚体的结合能力，从而影响细胞表型功能。计算毒理学的构效分析进一步证实了上述发现，表明BDE-47中的苯环与几种核受体蛋白发生共轭作用是其干扰细胞核受体的分子基础。总之，本研究结果表明BDE-47可通过干扰以RXRα受体为核心的多个重要细胞核受体的表达、扰动核受体间结合的平衡以及核受体间的相互作用从而诱导其生物毒性效应。本研究为揭示BDE-47毒性效应分子机制提供了理论依据。初步阐明以视黄醛X受体作为必需异源二聚体的多受体相互作用在PBDEs诱导神经毒性效应的作用机制，为阐明其一系列毒性效应机制提供了科学依据，也为揭示其它新兴环境热点化学污染物的毒性效应机制提供了科学参考。