THE ARYL HYDROCARBON RECEPTOR AND OVARIAN DEVELOPMENT

芳烃受体（AHR）是一种配体激活的转录因子，它与AHR核转运子（ARNT）结合到二恶英反应元件（DREs）上，调控基因表达。2,3,7,8 -四氯二苯并-对二恶英（TCDD）是AHR配体。已知TCDD会产生多种生理和病理反应，包括脊椎动物的生殖功能障碍。AHR被认为在细胞周期中发挥作用，最近的证据表明，这可能通过与视网膜母细胞瘤肿瘤抑制基因的产物相互作用而发生。视网膜母细胞瘤蛋白结合细胞周期从G1期到S期进展所必需的转录因子。AHR上的两个不同区域与低磷酸化的pRB形成独立的复合物，这种相互作用通过AHR配体结合而增强。本研究的中心假设是AHR信号通路在卵巢正常发育中起重要作用，当环境污染物破坏时，卵子发生改变。与哺乳动物模型不同，眼底细胞表达AHR的两种不同的类似性。这些ahr在其组织特异性表达以及推定的pRB结合位点上有所不同。研究这些受体在卵巢眼底的功能差异，将进一步明确哺乳动物AHR同源物Fundulus AHR1在细胞生理学中的作用。在受卤代芳烃污染的地区，眼底种群对二恶英的毒性作用产生了遗传抗性。我们将从两个角度探讨AHR在卵巢发育中重要的中心假设。为了验证AHR1和AHR2在卵巢发育中功能不同的假设，我们将通过免疫细胞化学方法评估ahr在生殖阶段卵巢细胞类型中的表达。细胞特异性凋亡和组织病理学将在TCDD治疗的二恶英耐药和敏感的眼底进行评估。AHR1和AHR2与pRB的相互作用将通过克隆和表征眼底pRB以及使用体外结合试验来评估AHR的结合来研究。

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that, together with the AHR nuclear translocator (ARNT), binds to dioxin responsive elements (DREs) to regulate gene expression. 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) is an AHR ligand. TCDD is known to produce a wide variety of physiological and pathological responses, including reproductive dysfunction in vertebrates. The AHR is thought to play a role in the cell cycle, and recent evidence suggests that this may occur through an interaction with the product of the retinoblastoma tumor suppressor gene. The retinoblastoma protein binds transcription factors necessary for cell cycle progression from G1 to S phase. Two distinct regions on the AHR form independent complexes with hypophosphorylated pRB and this interaction is enhanced by AHR ligand binding. The central hypothesis of this study is that the AHR signaling pathway plays an important role in normal ovarian development, and when disrupted by environmental contaminants, oogenesis is altered. Unlike mammalian models, Fundulus express two divergent paralogs of the AHR. These AHRs differ in their tissue specific expression as well as in the putative pRB binding sites. Investigating the functional differences between these receptors in the Fundulus ovary will further define the role of Fundulus AHR1, the mammalian AHR homolog, in cellular physiology. Fundulus populations in areas contaminated with halogenated aromatic hydrocarbons develop heritable resistance to the toxic effects of dioxin. We will approach the central hypothesis that the AHR is important in ovarian development from two perspectives. To test the hypothesis that Fundulus AHR1 and Fundulus AHR2 are functionally distinct in ovarian development we will evaluate expression of the AHRs in ovarian cell types among reproductive stages by immuncytochemistry. Cell specific apoptosis and histopathology will be assessed in TCDD treated dioxin resistant and sensitive Fundulus. Interactions of AHR1 and AHR2 with pRB will be investigated by cloning and characterizing pRB in Fundulus and by the use of in vitro binding assays to assess AHR binding.