Epigenic effects of environmental toxicants on cellular communication pathways

化学品，如多氯联苯、多溴联苯、四氯二苯并对二恶英、滴滴涕、过氧化物酶体、增殖剂等，其与实验动物的出生缺陷、癌症、生殖和神经行为功能障碍有关，通过“表观遗传”而不是通过遗传毒性机制起作用[它们都已被证明抑制间隙连接细胞间通讯（GJIC）]。这项跨学科项目的目标是利用具有干细胞样潜能的体外人类神经元细胞系，研究神经元细胞的分子生物学特性。（改变基因表达），生物化学（各种有丝分裂/分化、信号转导系统）和细胞（GFIC）、细胞增殖、细胞分化、凋亡]机制，这些机制可能受到暴露于环境毒物之前或之后的影响，生物或化学补救方法。该提案包含了我们与苏珊博士和W博士在以前的超级基金项目中合作的扩展。Weber使用我们的大鼠肝上皮GJIC测定来评估其补救技术的功效，以及一个新项目来研究人类神经元细胞中GJIC调制与化学诱导的信号转导和基因表达改变的关系。工作假设将是确定有毒化学物质对GJIC的阻断是否是由特定的信号转导机制介导的，所述信号转导机制可能改变特定基因组的表达，所述特定基因组反过来可能影响细胞调节增殖、细胞分化或凋亡的能力。提出了三个具体目标：目标1：使用具有已知结构/功能关系的已知模型毒物来鉴定与细胞行为改变相关的特异性细胞内信号传导;目标：如目标1中所述，使用经修复的混合物来研究信号传导途径，以筛选各种修复策略的功效;目标3：测试新的DNA微阵列技术是否可用于鉴定与目的1和2的GJIC改变和细胞终点研究相关的基因表达改变。其意义在于提供GJIC抑制作为化学品的预测终点的验证，所述化学品可通过其触发改变控制细胞增殖、细胞分化、凋亡或分化细胞的适应性反应的基因表达的各种信号转导机制的能力而具有毒性。此外，在人体体外系统中使用DNA微阵列技术，可以控制许多混杂因素，识别与化学诱导的信号转导系统及其相关的生物学效应相关的基因，可能比使用动物系统的组织更容易和更相关的人类风险评估的外推。

Chemicals, such as PCB's, PBB's, TCDD, DDT, peroxisomes, proliferators, etc., which have been associated with birth defects, cancer, reproductive and neuro-behavioral dysfunctions in experimental animals, work by "epigenetic", not by genotoxic mechanisms [They all have been demonstrated to inhibit gap junctional intercellular communication (GJIC)]. The goal of the interdisciplinary project is to use an in vitro human neuron cell line with stem cell-like potential, to study the molecular (altered gene expression), biochemical (various mitogenetic/differentiation, signal transducing systems) and cellular (GFIC), cell proliferation, cell differentiation, apoptosis] mechanisms that might be affected by exposure to environmental toxicants prior to, or post, biological or chemical remediation processes. The proposal contains both an extension of our collaboration in the previous Superfund Program Project with Dr. Susan and Dr. W. Weber to assess the efficacy of their remediation techniques using our rat liver epithelial GJIC assay, as well as a new project to study the relationship of the modulation of GJIC in human neurons cells to chemically-induced signal transduction, to alterations in gene expression. The working hypothesis will be to determine if the blockage of GJIC by toxic chemicals is mediated by specific signal transduction mechanisms which might alter the expression of specific battery of genes which, in turn, could affect the cell's ability to regulate proliferation, cell differentiation or apoptosis. Three specific aims are proposed: Aim 1: To use known model toxicants with known structure/function relations to identify specific intracellular signaling associated with alterations of cell behavior; Aim : To study the signaling pathways, as in Aim 1, with the remediated mixtures to screen the efficacy of various remediation strategies; Aim 3: To test if the new DNA microarray technology can be used to identify altered gene expression associated with the altered GJIC and cellular endpoint studies of Aims 1 and 2. The significance is to provide validation of the inhibition of GJIC as a predictive endpoint of chemicals that can be toxic via their ability to trigger various signal transduction mechanisms that alter gene expression controlling either cell proliferation, cell differentiation, apoptosis or adaptive response of differentiated cells. In addition, using DNA microarray technology on a human in vitro system where many confounding factors can be controlled, identification of those genes associated with chemical-induced signal transduction systems and their associated biological effects might be easier and more relevant to the extrapolation of risk assessment in human beings, than the use of tissues from animal systems.