Molecular and Cellular Basis of PCB Developmental Neurotoxicity

项目总结/摘要 多氯联苯（PCBs）仍然对人类健康构成重大风险， 大脑发育。关于多氯联苯发育神经毒性（DNT）的研究几乎完全集中在 高氯化（HC）-多氯联苯;相反，我们对LC-PCB干扰 神经发育是非常有限的。这是一个令人不安的数据差距，根据我们在以前的发现， 在项目期间，LC-PCBs 11和28占孕妇血清中多氯联苯的70%以上， 增加孩子患有神经发育障碍（NDD）的风险。我们发现PCB 11及其 通过细胞色素P450（CYP）介导的氧化形成的代谢物促进树突和轴突生长， 体外这些影响是在与人类妊娠环境相关的PCB 11浓度下观察到的， 代谢产物的效力与母体不同。我们的初步数据表明，PCB 11 通过激活CREB依赖性信号通路引起DNT。代谢物是否会改变 通过相同的分子机制的神经发育是未知的。这些发现是第一个 确定LC-PCB的DNT潜力，提出几个关键问题，必须解决这些问题以确定风险 LC-PCBs对发育中的人类大脑的影响：（1）在妊娠环境中发现的LC-PCBs是否会改变 神经系统的发育(2)LC-PCBs改变的分子机制是什么 神经元形态发生(3)人类CYP介导的代谢是否激活LC-PCB发育 神经毒剂为了解决这些问题，我们将测试CYP介导的 代谢影响LC-PCBs对CREB依赖的神经发育过程的体内效应。到 为了验证这一新的假设，我们将利用最先进的小鼠模型， CYP 2A 6或CYP 2B 6，但不包括小鼠Cyp 2a、2b、2f 2、2g 1和2s 1蛋白（Cyp 2abfgs缺失小鼠）。专注于 LC-PCBs记录在人类妊娠环境和发育中的大脑，我们将（a）确定LC- 通过人CYP 2A 6和CYP 2B 6形成的PCB代谢物，并测试其对CREB依赖性 在原代神经元-神经胶质共培养物中的神经发育过程;和（B）确定LC-神经胶质细胞的调节方式。 体内PCB代谢影响LC-PCB DNT的量效关系。预期成果 这些研究包括确定LC-PCB作为一类新的环境污染物， 干扰神经发育和关于CREB信号传导作用的新机制数据， 介导的生物活化。这项研究不仅会产生数据， 迫切需要评估LC-PCB对发育中的大脑造成的风险，但也需要提供关键的 关于饮食和/或药理学操纵抗肿瘤活性的可行性的机制见解， 降低脆弱亚群的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.