PURINES AND THE MAINTENANCE OF MEIOTIC ARREST

嘌呤和减数分裂停滞的维持

• 批准号: 2199492
• 负责人: STEPHEN M DOWNS
• 金额: $ 9.33万
• 依托单位: MARQUETTE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-12-01 至 1998-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2199492
• 关键词: adenosine; cyclic AMP; egg /ovum; follicle stimulating hormone; glucose metabolism; high performance liquid chromatography; hormone regulation /control mechanism; hypoxanthine phosphoribosyltransferase; hypoxanthines; laboratory mouse; meiosis; oogenesis; pentose phosphate shunt; phosphorylation; purine /pyrimidine metabolism; radiotracer

A major goal of my research program is to identify molecules and metabolic pathways that participate in the control of oocyte maturation in mammals. The current proposal will test the idea that modulation of purine metabolism has direct influence on the mechanisms controlling meiotic maturation and that glucose metabolism plays an important role in this control. Purines and their associated metabolic pathways have been implicated as important participants in the mechanisms controlling meiotic maturation. Results of experiments conducted during the current grant period have led to the hypothesis that hypoxanthine maintains meiotic arrest through a cooperative interaction with the purine de novo nucleotide-generating pathways. We have also investigated the involvement of different energy sources in oocyte maturation and have determined that the uptake and metabolism of glucose is required for gonadotropin-induced germinal vesicle breakdown in meiotically arrested cumulus cell-enclosed oocytes in vitro. Further preliminary work suggests that the positive action of gonadotropins may be mediated by the pentose phosphate pathway (PPP) but not glycolysis. We hypothesize that metabolism of glucose through the PP mediates the maturation-inducing effects of follicle-stimulating hormone (FSH) by its effects on purine metabolism. Phosphoribosylpyrophosphate, a compound whose levels rise with increased PPP activity, can serve as an important link between carbohydrate use as a model system the oocyte-cumulus cell complex isolated from immature mice that were primed 48th with pregnant mare serum gonadotropin. Part I will address the effects of FSH on both purine and glucose metabolism in the oocyte-cumulus cell complex as it relates to the meiotic status of the oocyte. By using radiolabeled purines, purine precursors and glucose, we will determine via biochemical assays and HPLC address analyses what metabolic changes occur prior, to and during, FSH-induced meiotic maturation. Part II will address how alteration of specific intermediary steps of the purine metabolic pathways affects other metabolic steps as well as the control of meiotic arrest. Attention will be focused on de novo purine synthesis, the purine salvage pathway, and the nucleoside phosphorylating pathways (ie, adenosine to ATP and guanosine to GTP). In all of these experiments the site of action will be determined by analyzing the oocyte and cumulus cells separately. The proposed experiments will help delineate specific purine metabolic pathways involved in the maintenance of meiotic arrest and in FSH-induced maturation and will help define the role of carbohydrate metabolism in these processes. These results will have important implications for both fertility and contraception, since each is affected by the ability of the oocyte to successfully initiate and complete meiotic maturation. The data will also benefit the development of in vitro systems where either meiotic arrest or completion of meiotic maturation is the desired endpoint.

我的研究计划的一个主要目标是识别分子和 参与控制卵母细胞成熟的代谢途径 在哺乳动物中。 目前的提案将测试调制的想法 嘌呤代谢对控制机制有直接影响 减数分裂成熟和葡萄糖代谢起着重要作用 在这个控制中。 嘌呤及其相关代谢途径 被认为是控制机制的重要参与者 减数分裂成熟。 当前进行的实验结果 授予期导致了次黄嘌呤维持的假设 通过与嘌呤 de novo 的合作相互作用来阻止减数分裂 核苷酸生成途径。 我们还调查了 不同的能量来源参与卵母细胞的成熟并具有 确定葡萄糖的摄取和代谢是必需的 促性腺激素诱导的减数分裂停滞中的生发囊泡破裂 体外卵丘细胞封闭的卵母细胞。 进一步的前期工作 表明促性腺激素的积极作用可能是由 磷酸戊糖途径 (PPP)，但不参与糖酵解。 我们假设 葡萄糖通过 PP 的代谢介导成熟诱导 卵泡刺激素 (FSH) 对嘌呤的影响 代谢。 磷酸核糖焦磷酸，一种水平升高的化合物 随着 PPP 活动的增加，可以作为 使用碳水化合物作为模型系统卵母细胞-卵丘细胞复合体 从未成熟的小鼠中分离出来，这些小鼠在第 48 代与怀孕的母马一起进行了免疫接种 血清促性腺激素。 第一部分将讨论 FSH 对两者的影响 卵母细胞-卵丘细胞复合物中的嘌呤和葡萄糖代谢 与卵母细胞的减数分裂状态有关。 通过使用放射性标记 嘌呤、嘌呤前体和葡萄糖，我们将通过生化测定 分析和 HPLC 可以分析代谢变化之前发生的情况， 以及 FSH 诱导的减数分裂成熟期间。 第二部分将讨论如何 嘌呤代谢特定中间步骤的改变 途径影响其他代谢步骤以及减数分裂的控制 逮捕。 注意力将集中在嘌呤的从头合成上， 嘌呤补救途径和核苷磷酸化途径（即， 腺苷转化为 ATP，鸟苷转化为 GTP）。 在所有这些实验中 通过分析卵母细胞和卵丘来确定作用位点 细胞分开。 拟议的实验将有助于描述特定的嘌呤代谢 参与维持减数分裂停滞和 FSH 诱导的途径 成熟并将有助于确定碳水化合物代谢的作用 这些过程。 这些结果将对双方产生重要影响 生育和避孕，因为两者都受到自身能力的影响 卵母细胞成功启动并完成减数分裂成熟。 这 数据还将有利于体外系统的开发，其中 减数分裂停滞或减数分裂成熟完成是所期望的 端点。