Investigating the cellular and molecular mechanisms of lower-chlorinated polychlorinated biphenyl developmental neurotoxicity

项目摘要 多氯联苯（PCBs）仍然对人类健康构成重大风险， 大脑发育。流行病学研究已经报道了发育与肥胖之间的正相关。 暴露于多氯联苯和神经发育障碍（NDD）的风险增加;然而，实验研究 旨在评估这些关联的强度，并确定PCB DNT的生物学机制 几乎完全集中在高氯化（HC）-多氯联苯，主要同系物中发现的 遗留的商用多氯联苯混合物。与此相反，关于低氯化多氯联苯的潜力的数据表明， 对神经发育的影响非常有限。这是一个令人不安的差距，考虑到最近的报告， LC-PCB的环境水平在全球范围内不断增加，LC-PCB同系物11和28 在怀孕妇女的血清中，多氯联苯的含量超过70%， NDD。我们以前报道过PCB 11及其代谢产物是通过细胞色素P450（CYP）介导的， 氧化促进了体外树突和轴突的生长， 与人类妊娠环境有关。有趣的是，代谢物的效力与 父母我们的体外研究还表明，PCB 11通过激活CREB-1增强树突状细胞的生长。 依赖的信号通路，但代谢物是否通过相同的分子改变神经发育 机制尚不清楚。我们还知道（1）在人体组织中发现的其他LC-PCB是否具有DNT 活性;（2）LC-PCB或其代谢物调节其他已知受调节的神经发育结果 通过CREB依赖性信号传导，特别是轴突生长和神经元凋亡;或（3） 细胞色素P450介导的代谢为LC-PCB DNT。我的中心假设是LC-PCB及其 通过人CYP 2A 6和CYP 2B 6形成的代谢物通过以下途径改变原代神经元的神经发育： CREB依赖机制。为了验证这一假设，我将在体外表征的DNT概况， 人类相关的LC-PCB及其代谢物，评估特定人类如何代谢LC-PCB CYP影响DNT，并评估CREB在LC-PCB DNT中的作用。这项研究将产生数据 迫切需要为LC-PCBs可能对神经系统产生毒性作用的风险评估提供信息。 大脑发育来自这些研究的数据也将提供关于CREB作用的新的机制见解。 以及LC-PCB DNT中的CYPS。考虑到CREB中功能获得性突变与NDD的相关性， 人CYP中众所周知的功能多态性，涉及CREB和/或CYP介导的代谢的数据 在LC-PCB中，DNT将提出关于影响NDD的基因-环境相互作用的可检验假设 风险和可能的饮食和/或药物战略，以减少风险人群中的LC-PCB DNT。

PROJECT SUMMARY Polychlorinated biphenyls (PCBs) remain a significant risk to human health, and a primary target of concern is the developing brain. Epidemiological studies have reported positive associations between developmental exposures to PCBs and increased risk for neurodevelopmental disorders (NDD); however, experimental studies designed to assess the strength of these associations and identify biological mechanisms underlying PCB DNT have focused almost exclusively on the higher chlorinated (HC)-PCBs, the predominant congeners found in the legacy commercial PCB mixtures. In contrast, data regarding the potential for lower chlorinated (LC)-PCBs to interfere with neurodevelopment is extremely limited. This is a troubling gap considering recent reports that environmental levels of LC-PCBs are increasing worldwide and that the LC-PCB congeners 11 and 28 were found to comprise >70% of PCBs in the serum of pregnant women at increased risk for having a child with an NDD. We previously reported that PCB 11 and its metabolites formed via cytochrome P450 (CYP)-mediated oxidation promoted dendritic and axonal growth in vitro, and these effects were observed at concentrations relevant to the human gestational environment. Interestingly, the potency of the metabolites varied from that of the parent. Our in vitro studies also suggested that PCB 11 enhanced dendritic growth via activation of CREB- dependent signaling pathways, but whether the metabolites alter neurodevelopment via the same molecular mechanism is not known. We also do we know whether (1) other LC-PCBs found in human tissues have DNT activity; (2) LC-PCBs or their metabolites modulate other neurodevelopmental outcomes known to be regulated by CREB-dependent signaling, specifically axonal growth and neuronal apoptosis; or (3) the contribution of cytochrome P450-mediated metabolism to LC-PCB DNT. My central hypothesis is that LC-PCBs and their metabolites formed via human CYP2A6 and CYP2B6 alter neurodevelopment in primary neurons via CREB-dependent mechanisms. To test this hypothesis, I will be characterizing the in vitro DNT profile of human-relevant LC-PCBs and their metabolites, assessing how the metabolism of LC-PCBs by specific human CYPs influences DNT, and evaluating the role of CREB in LC-PCB DNT. This research will generate data critically needed to inform risk assessments of the potential for LC-PCBs to exert neurotoxic effects on the developing brain. Data from these studies will also provide novel mechanistic insights regarding the role of CREB and CYPS in LC-PCB DNT. Given the association of gain-of-function mutations in CREB with NDDs, and the well-known functional polymorphisms in human CYPs, data implicating CREB and/or CYP-mediated metabolism in LC-PCB DNT would suggest testable hypotheses regarding gene-environment interactions that influence NDD risk and possible dietary and/or pharmacological strategies for reducing LC-PCB DNT in at-risk populations.