MECHANISMS OF ARYL HYDROCARBON INDUCED OVOTOXICITY

流行病学和动物研究数据表明， 多环芳烃（PAHs）导致卵巢滤泡 退化;然而，多环芳烃破坏 女性生殖细胞未知。 最近的研究 证明了存在一种细胞内结合蛋白， 多环芳烃被称为芳烃受体复合物（AHRC）。 由于AHRC作为基因的转录调节因子发挥作用， 在配体结合之后，多环芳烃的作用可以直接 通过改变基因表达介导。 此外，PAH 由包括卵巢细胞在内的许多细胞代谢， 这些中间体可以破坏细胞的氧化状态。 作为 因此，多环芳烃也可能通过以下方式间接导致卵泡破坏： 与氧化应激相关的途径。 最近的数据表明， 细胞凋亡的基本作用，以及由几种 最近的特点是“细胞死亡基因”，在正常的磨损， 卵巢生殖细胞和卵泡。 特别感兴趣的是 bax基因编码一种死亡易感因子， 是卵巢细胞死亡所必需的 bax基因启动子 含有由氧化激活的转录反应元件 应力以及共有芳烃响应元件 （AHRE），这表明多环芳烃可以诱导bax的表达， 直接（AHRE）和间接（氧化应激）机制。 因此，假设PAH诱导的生殖细胞损失是 通过凋亡介导，并且这种凋亡通过 直接激活（PAH-AHRC通过AHRE起作用）， 间接（PAH代谢和氧化应激）途径导致 促进bax表达。 为了解决这个假设， 提出了以下具体目标：1）表征剂量- 多环芳烃对生殖细胞凋亡的时间依赖性影响 以及胎儿和出生后小鼠卵巢的卵泡颗粒细胞; 2)为了确定在生殖细胞中bax基因表达是否增加， 和颗粒细胞暴露于多环芳烃，如果这种反应和 细胞凋亡诱导依赖于PAH-AHRC 相互作用; 3）评估PAH是否导致氧化应激 代谢参与PAH诱导的卵毒性; 4）使用 BAX功能丧失小鼠模型，以确定功能性BAX 蛋白质是多环芳烃的卵毒性作用所必需的;以及5） 评估BAX拮抗剂的过表达（BAX拮抗剂的产物）是否与BAX拮抗剂的过表达相关。 bcl-2生存基因）表达的保护作用， PAH诱导的细胞凋亡。 利用最先进的分子技术 生物学方法，这些研究的长期目标是 破译细胞内的效应途径，介导 多环芳烃对卵巢生殖细胞（卵母细胞）的有害作用， 颗粒细胞作为一种手段，以确定新的干预网站， 防止毒物引起的组织损伤

Data from epidemiological and animal studies suggest that polycyclic aromatic hydrocarbons (PAHs) cause ovarian follicular degeneration; however, the mechanisms by which PAHs destroy female germ cells are unknown. Recent studies have demonstrated the existence of an intracellular binding protein for PAHs termed the aryl hydrocarbon receptor complex (AHRC). Since the AHRC functions as a transcriptional regulator of genes following ligand binding, the actions of PAHs may be directly mediated via altered gene expression. Additionally, PAHs are metabolized by many cells including those of the ovary, to reactive intermediates that can disrupt the oxidative state of the cell. As such, PAHs may also cause follicular destruction indirectly by pathways associated with oxidative stress. Recent data support a fundamental role for apoptosis, and proteins encoded by several recently characterized "cell death genes," in the normal attrition of ovarian germ cells and follicles. Of particular interest is the gene, bax, which encodes a death-susceptibility factor that appears to be required for ovarian cells to die. The bax gene promoter contains transcriptional response elements activated by oxidative stress, as well as a consensus aryl hydrocarbon response element (AHRE), suggesting that PAHs can induce bax expression by both direct (AHRE) and indirect (oxidative stress) mechanisms. Therefore, it is hypothesized that PAH-induced germ cell loss is mediated via apoptosis, and that this apoptosis occurs via activation of direct (PAH-AHRC acting via the AHRE) and indirect (PAH metabolism and oxidative strees) pathways leading to enhanced bax expression. To address this hypothesis, the following specific aims are proposed: 1) to characterize the dose- and time-dependent effects of PAHs on apoptosis in germ cells and follicular granulosa cells of fetal and post-natal mouse ovaries; 2) to determine if bax gene expression is increased in germ cells and granulosa cells exposed to PAHs, and if this response and the induction of apoptosis are dependent upon PAH-AHRC interaction; 3) to evaluate if oxidative stress resulting from PAH metabolism is involved in PAH-induced ovotoxicity; 4) to use a BAX loss-of-function mouse model to determine if functional BAX protein is required for the ovotoxic effects of PAHs; and 5) to evaluate if overexpression of BAX antagonist (the product of the bcl-2 survival gene) in mouse oocytes conveys protection from PAH-induced apoptosis. Using state-of-the-art molecular biological approaches, the long-range goal of these studies is to decipher the intracellular effector pathways that mediate the deleterious actions of PAHs in ovarian germ cells (oocytes) and granulosa cells as a means to identify novel sites of intervention for precenting toxicant-induced tissue damage.