Cell Cycle Regulation In Oogenesis

卵子发生中的细胞周期调控

• 批准号: 6541221
• 负责人: MARY A LILLY
• 金额: --
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6541221
• 关键词: Drosophilidae; arthropod genetics; cell cycle; cell differentiation; cell growth regulation; developmental genetics; female; gene mutation; genetic regulation; oogenesis

The unit on cell cycle regulation uses Drosophila oogenesis as a model system to examine the developmental regulation of the cell cycle. Our current research focuses on two problems: the switch from the mitotic cycle to the meiotic cycle and the relationship between cell cycle regulation and oocyte differentiation. Animal oocytes undergo a highly conserved developmental arrest in prophase of meiosis I. Often this marks a period of rapid growth for the oocyte and is necessary to coordinate meiotic progression with the developmental events of oogenesis. In Drosophila a single oocyte develops within a 16-cell germline cyst. Throughout much of oogenesis the oocyte remains arrested in prophase of meiosis I. In contrast, its 15 mitotic sisters enter the endocycle and become polyploid in preparation for their role as nutritive nurse cells. How germline cysts establish and maintain these two independent cell cycles is unknown. We have demonstrated a role for the p21CIP/p27Kip1/p57Kip2 like cyclin-dependent kinase inhibitor (cki) dacapo (dap) in the maintenance of the prophase I meiotic arrest of the Drosophila oocyte. In Drosophila cyclinE-Cdk2 activity is required for entry into S phase. In the absence of Dap, the oocyte enters the endocycle and develops as a nurse cell. These studies have revealed a novel meiotic function for the Cip/Kip family of Cdk inhibitors. We are continuing to examine how Dap is spatially and temporally regulated during germline cyst formation and maturation. We have used a genetic screen, based on the FLP/FRT site-specific recombinase system, to identify additional genes that regulate the cell cycle during oogenesis. The FLP/FRT system allows one to examine small clones of mutant tissue in the background of a phenotypically wild-type animal. Using this technique we recently identified the 183B gene. Mutations in 183B result in the loss of the prophase I meiotic arrest of the oocyte. Antibodies generated against the 183B gene product indicate that it is one of the first proteins to be localized specifically to the oocyte nucleus during the differentiation of the ovarian cyst. Molecular analysis shows that 183B has limited homology to a family of retinoblastoma protein binding factors. We are currently continuing the phenotypic analysis of the 183B mutants. In addition, we are attempting to identify genes that interact with 183B using both genetic and biochemical approaches. In metazoans relatively little is known about what controls the switch from the mitotic to the meiotic cycle during gametogenesis. In our FLP:FRT screen we identified a mutant in which ovarian cysts undergo an extra mitotic division before entering the meiotic cycle. Molecular analysis of this mutant indicates that it is an antimorphic allele of the twine gene. twine encodes a germline specific form of the mitotic activator cdc25. We are currently using this mutant to examine how the timing of the germline cyst divisions influence entry into the meiotic cycle.

细胞周期调节的单位使用果蝇卵子形成作为模型系统来检查细胞周期的发育调控。我们当前的研究重点是两个问题：从有丝分裂循环到减数分裂周期以及细胞周期调节与卵母细胞分化之间的关系。动物卵母细胞在减数分裂的预言中经历了高度保守的发育停滞。这通常标志着卵母细胞的快速生长时期，对于将减数分裂进程与卵子发生事件进行协调。在果蝇中，单个卵母细胞在16细胞种系囊肿内形成。在大部分卵子发生过程中，卵母细胞在减数分裂的预言中被捕。相比之下，其15个有丝分裂姐妹进入了内吞以进行多倍体，为它们作为营养护士细胞的作用做准备。种系囊肿如何建立和维持这两个独立的细胞周期是未知的。我们已经证明了P21CIP/P27KIP1/p57KIP2，例如细胞周期蛋白依赖性激酶抑制剂（CKI）DACAPO（DAP）在维持果蝇的预言I减数分裂的维持中。在果蝇中，进入S相需要的是Cycline-CDK2活性。在没有DAP的情况下，卵母细胞进入内猫并作为护士细胞发展。这些研究揭示了CDK抑制剂的CIP/KIP家族的新型减数分裂功能。我们正在继续研究在生殖线囊肿形成和成熟过程中DAP在空间和时间上的调节。我们使用了基于FLP/FRT位点特异性重组酶系统的遗传筛选来鉴定调节卵子发生过程中细胞周期的其他基因。 FLP/FRT系统允许在表型野生型动物的背景下检查突变组织的小克隆。使用此技术，我们最近确定了183b基因。 183b的突变导致卵母细胞的预言损失。与183b基因产物产生的抗体表明，它是卵巢囊肿分化过程中最早将其定位于卵母细胞核的蛋白质之一。分子分析表明，183b与视网膜细胞瘤蛋白结合因子系列的同源性有限。我们目前正在继续对183b突变体的表型分析。此外，我们正在尝试使用遗传和生化方法鉴定与183B相互作用的基因。在后代人中，关于在配子发生过程中从有丝分裂到减数分裂周期的转换的转换相对较少。在我们的FLP：FRT屏幕中，我们确定了一个突变体，其中卵巢囊肿在进入减数分裂周期之前会经历额外的有丝分裂分裂。该突变体的分子分析表明它是麻线基因的抗鲜相等位基因。麻线编码有丝分裂激活剂Cdc25的种系特异性形式。我们目前正在使用该突变体来检查种系囊肿分裂的时机如何影响进入减数分裂周期。