Mechanism of Prenatal Chromium-VI Exposure and Germ Cell Apoptosis in the Ovary

 描述（由申请方提供）：产前发育期间宫内暴露于环境内分泌干扰物（EDCs）导致F1代后代生殖细胞丢失、卵母细胞损伤、绝经早期和流产增加。六价铬（CrVI）是一种重金属内分泌干扰物。由于CrVI的工业使用增加和工业废物的不当处置，美国饮用水源中的CrVI水平一直在上升，对人类健康构成重大威胁。Cr穿过胎盘屏障到达子宫内生长的胎儿，影响胚胎发育、胎儿活力和生殖功能。通过环境或职业暴露暴露于六价铬的妇女患有妇科疾病，如月经异常、产后出血增加、早产、死产和不孕症，并伴有尿液、外周血和脐带血以及胎盘组织中的高铬水平。Cr可到达卵巢并在女性卵泡液中积聚。这一重大的职业和公共卫生问题强调了了解CrVI引起的生殖功能障碍的重要性。拟议研究的目的是了解产前暴露于CrVI破坏生殖细胞存活、生殖细胞巢破裂和F1子代卵泡发育、卵母细胞质量和囊胚发育的早期事件的分子、细胞和表观遗传机制。总体假设是，产前暴露于CrVI增加生殖细胞的凋亡，加速生殖细胞巢破裂，损害卵母细胞的质量，并破坏F1后代的囊胚发育。具体目标1将确定产前暴露于CrVI对F1后代生殖细胞凋亡和生殖细胞巢破坏的分子和细胞机制。具体目标2将建立活性氧（ROS），p53和半胱天冬酶-3途径在CrVI诱导的生殖细胞凋亡和生殖细胞巢破裂的选择性和相互作用的作用。具体目标3将确定产前暴露于CrVI对卵母细胞质量和F1后代早期胚胎发育的影响。实验方法包括暴露于环境相关和监管剂量的六价铬在胎儿卵巢发育过程中使用体内大鼠模型，体外胎儿全卵巢器官培养，药理学和基因组方法，超排卵，卵母细胞和囊胚发育能力和细胞，分子和显微镜为基础的技术。该项目的新发现有望填补了解子宫内暴露于CrVI如何影响F1后代生殖功能所需知识的差距。结果将确定CrVI对胎儿卵巢发育早期窗口的影响，这些新知识可能有助于教育孕妇在这些关键窗口期间避免暴露于CrVI。本研究中使用的实验模型和确定的结果可以外推，以了解其他重金属和内分泌干扰物对包括人类在内的哺乳动物物种的卵巢发育和产前健康和疾病规划的不利影响。

 DESCRIPTION (provided by applicant): In utero exposure to environmental endocrine disrupting chemicals (EDCs) during prenatal development results in germ cell loss, oocyte damage, early menopause, and increased miscarriages in F1 progeny. Hexavalent chromium (CrVI) is a heavy metal endocrine disruptor. CrVI levels in drinking water sources in the United States have been increasing due to increased industrial use of CrVI and improper disposal of industrial waste, imposing a major threat to human health. Cr traverses the placental barrier and reaches the growing fetus in utero, affecting embryonic development, fetal viability, and reproductive functions. Women exposed to CrVI through environmental or occupational exposures suffer from gynecological illnesses such as abnormal menses, increased postpartum bleeding, pre-term birth, stillbirth, and infertility, accompanied by high Cr levels in their urine peripheral and umbilical cord blood, and placental tissue. Cr can reach the ovary and accumulate in the follicular fluid in women. This significant occupational and public health concerns underscore the importance of understanding CrVI-induced reproductive dysfunctions. The objective of the proposed research is to understand the molecular, cellular, and epigenetic mechanisms by which prenatal exposure to CrVI disrupts germ cell survival, germ cell nest breakdown and early events of follicular development, oocyte quality, and blastocyst development in F1 progeny. The overarching hypothesis is that prenatal exposure to CrVI increases apoptosis of germ cells, accelerates germ cell nest breakdown, impairs oocyte quality, and disrupts blastocyst development in F1 progeny. Specific Aim 1 will determine the molecular and cellular mechanism of prenatal exposure to CrVI on germ cell apoptosis and germ cell nest breakdown in F1 progeny. Specific Aim 2 will establish the selective and interactive roles of reactive oxygen species (ROS), p53, and caspase-3 pathways in CrVI-induced germ cell apoptosis and germ cell nest breakdown. Specific Aim 3 will determine the impact of prenatal exposure to CrVI on oocyte quality and early embryonic development in F1 progeny. The experimental approaches include exposure to environmentally relevant and regulatory doses of CrVI during fetal ovarian development using in vivo rat models, in vitro fetal whole ovary organ culture, pharmacological and genomic approaches, superovulation, oocyte and blastocyst developmental competence and cellular, molecular, and microscopy-based techniques. The novel findings from this project are expected to fill the gap in knowledge needed to understand how the in utero exposure to CrVI affects reproductive functions in the F1 progeny. Results will identify the effect of CrVI on early windows of great vulnerability of fetal ovarian development, and this new knowledge may help to educate pregnant women to avoid exposures to CrVI during such critical windows. The experimental model used and outcomes identified in this study can be extrapolated to understand the adverse effects of other heavy metals and EDCs on ovarian development and prenatal programming of health and disease across the mammalian species including human.