Molecular and Cellular Basis of PCB Developmental Neurotoxicity

项目摘要/摘要 多氯联苯(多氯联苯)仍然对人类健康构成重大威胁，令人担忧的主要目标是 发育中的大脑。多氯联苯发育神经毒性(DNT)的研究几乎完全集中在 氯化程度较高的多氯联苯；相比之下，我们对液晶多氯联苯潜在干扰的理解 神经发育极其有限。这是一个令人不安的数据差距，因为我们在之前的 项目期内，LC-PCB11和28占孕妇血清多氯联苯的70% 生出患有神经发育障碍(NDD)的孩子的风险增加。我们发现PCB11及其 细胞色素P450(CYP)介导的代谢产物促进大鼠脑内树突状细胞和轴突生长 体外培养。在与人类妊娠环境相关的多氯联苯11浓度下观察到这些影响， 代谢产物的效力与母体的不同。我们的初步数据显示，PCB11 通过激活依赖于CREB的信号通路导致DNT。代谢物是否会改变 通过相同的分子机制进行的神经发育尚不清楚。这些发现是第一次发现 确定液晶多氯联苯的DNT潜力，提出几个必须解决的关键问题以确定风险 液晶多氯联苯对发育中的人脑的影响：(1)在妊娠环境中发现的液晶多氯联苯是否会改变 完整大脑的神经发育？(2)液晶多氯联苯改变的分子机制是什么(S) 神经元形态发生？(3)人类CYP介导的代谢是否激活LC-PCbs以促进发育 神经毒药？为了解决这些问题，我们将测试CYP介导的中心假设 代谢影响LC-PCbs对CREB依赖的神经发育过程的体内效应。至 测试这个新的假设，我们将利用最先进的小鼠模型来表达人类 小鼠Cyp2a、2b、2f2、2g1和2s1蛋白(Cyp2abfgs缺失小鼠)。专注于 LC-多氯联苯记录在人类妊娠环境和发育中的大脑，我们将(A)确定LC- 人CYP2A6和CYP2B6形成的多氯联苯代谢产物及其对CREB依赖性的影响 原代神经元-神经胶质细胞共培养中的神经发育过程；以及(B)决定LC-Lc的调制方式。 多氯联苯在体内的代谢影响LC-多氯联苯DNT的量效关系。预期的结果 这些研究包括将液晶多氯联苯鉴定为一类新的环境污染物， 干扰神经发育和有关CREB信号和CYP作用的新机制数据- 在多氯联苯DNT中介导生物活化。这项研究将不仅通过产生数据来影响公共健康 迫切需要评估LC-PCbs对发育中的大脑构成的风险，但也通过提供关键的 关于饮食和/或药物操纵CYP活性的机械论见解 降低易受伤害人群中的DNT风险。

PROJECT SUMMARY/ABSTRACT Polychlorinated biphenyls (PCBs) remain a significant risk to human health, and a primary target of concern is the developing brain. Research on PCB developmental neurotoxicity (DNT) has focused almost exclusively on the higher chlorinated (HC)-PCBs; in contrast, our understanding of the potential for LC-PCBs to interfere with neurodevelopment is extremely limited. This is a troubling data gap in light of our discovery during the previous project period that the LC-PCBs 11 and 28 comprise >70% of the PCBs in the serum of pregnant women at increased risk for having a child with a neurodevelopmental disorder (NDD). We found that PCB 11 and its metabolites formed via cytochrome P450 (CYP)-mediated oxidation promote dendritic and axonal growth in vitro. These effects are observed at PCB 11 concentrations relevant to the human gestational environment, and the potency of the metabolites varied from that of the parent. Our preliminary data suggest that PCB 11 causes DNT via activation of CREB-dependent signaling pathways. Whether the metabolites alter neurodevelopment via the same molecular mechanism is not known. These findings, which were the first to identify the DNT potential of LC-PCBs, raise several critical questions that must be addressed to define the risk that LC-PCBs pose to the developing human brain: (1) Do LC-PCBs found in the gestational environment alter neurodevelopment in the intact brain? (2) What are the molecular mechanism(s) by which LC-PCBs alter neuronal morphogenesis? (3) Does human CYP-mediated metabolism activate LC-PCBs to developmental neurotoxicants? To address these questions, we will test the central hypothesis that CYP-mediated metabolism influences the in vivo effects of LC-PCBs on CREB-dependent neurodevelopmental processes. To test this novel hypothesis, we will leverage state-of-the-art mouse models engineered to express human CYP2A6 or CYP2B6 but not mouse Cyp2a, 2b, 2f2, 2g1, and 2s1 proteins (Cyp2abfgs-null mice). Focusing on LC-PCBs documented in the human gestational environment and developing brain, we will (a) identify the LC- PCB metabolites formed via human CYP2A6 and CYP2B6, and test their effects on CREB-dependent neurodevelopmental processes in primary neuron-glia co-cultures; and (b) determine how modulation of LC- PCB metabolism influences the dose-response relationship of LC-PCB DNT in vivo. The anticipated outcomes of these studies include the identification of LC-PCBs as a new class of environmental contaminants that interfere with neurodevelopment and novel mechanistic data regarding the role of CREB signaling and CYP- mediated bioactivation in PCB DNT. This research will impact public health not only by generating data critically needed to assess the risk LC-PCBs pose to the developing brain, but also by providing critical mechanistic insights regarding the plausibility of dietary and/or pharmacological manipulation of CYP activity to mitigate DNT risk in vulnerable subpopulations.