Studies on ovarian ring canals in Drosophila

描述(申请人提供)：环形通道是稳定的细胞间连接，在细胞之间形成细胞质桥梁。在包括人类在内的大多数动物的卵巢和睾丸中，它们都存在于发育中的生殖细胞之间，在那里它们促进配子的同步发育。环管起源于生殖系增殖过程中胞质分裂受阻，随后用细胞骨架蛋白稳定停滞的卵裂沟。因此，环管发育始于一种修饰的有丝分裂。到目前为止，它们在雌性果蝇身上表现得最好，在整个卵子发生过程中，环形通道允许细胞质从哺育细胞流向卵母细胞。通过研究细胞质运输有缺陷的雌性不育突变体，已经发现了几个编码环管结构蛋白或调节器的基因。对这些基因的研究表明，女性环管的肌动蛋白细胞骨架是高度动态的，以适应环管的生长。此外，环管的初始形成与另一种生殖系结构--梭体紧密协调。该项目的目标是继续对果蝇环管的研究。其具体目的是：1)研究HTS基因编码的蛋白质在梭体和环道生物发生中的作用；2)进一步确定环道生长的动力学，包括测定卵室发育不同阶段的F-肌动蛋白周转率；以及3)开始鉴定体细胞中的环道。对HTS基因的研究可能会对细胞质分裂如何在与姐妹细胞形成稳定连接的细胞中进行修改提供重要的线索。在卵子发生过程中，环管直径以双相模式急剧扩大。较快的第二阶段依赖于Arp2/3。目的通过对标记有荧光蛋白的细胞骨架蛋白的遗传学和细胞学分析，探讨环管蛋白在Apr2/3非依赖生长的第一阶段的动态变化。虽然环管被认为是生殖系细胞的共同特征，但它们并不局限于生殖系细胞。然而，关于体细胞中环状通道的流行率、功能或分子组成的信息很少。目的三通过分析卵室中连接体细胞滤泡细胞的环管，开始解决这一信息的匮乏。基因分析将在蛋白质捕获筛查中确定的毛囊细胞环管蛋白上进行。与毛囊细胞环管丢失相关的表型可能会提供对它们在上皮细胞中功能的第一次洞察。

DESCRIPTION (provided by applicant): Ring canals are stable intercellular junctions that form cytoplasmic bridges between cells. They are present between developing germ line cells in both ovaries and testes in most animals, including humans, where they facilitate the synchronized development of gametes. Ring canals originate from arrested cytokinesis during germline proliferation, followed by stabilization of the stalled cleavage furrows with cytoskeletal proteins. Thus, ring canal development begins as a modified mitosis. They are best characterized so far in Drosophila females where ring canals allow the flow of cytoplasm from nurse cells to oocytes throughout oogenesis. By studying female sterile mutants in which cytoplasm transport is defective, several genes have been discovered that encode ring canal structural proteins or regulators. Work on these genes has revealed that the actin cytoskeleton of female ring canals is highly dynamic to accommodate ring canal growth. In addition, the initial formation of ring canals is tightly coordinated with another germline structure, the fusome. The goal of this project is to continue the study of ring canals in Drosophila. The specific aims are: 1) to characterize the roles of proteins encoded by the hts gene in fusome and ring canal biogenesis; 2) to further define the kinetics of ring canal growth including the determination of F-actin turnover rates during different stages of egg chamber development; and 3) to begin characterizing ring canals in somatic cells. Work on the hts gene is likely to shed important light on how cytokinesis is modified in cells that form stable junctions with their sisters. Ring canal diameter expands dramatically during oogenesis in a biphasic pattern. The more rapid second phase is Arp2/3-dependent. Aim two will explore ring canal protein dynamics in during the first phase of Apr2/3-independent growth using genetic and cellular analyses of cytoskeletal proteins tagged with fluorescent proteins. Although ring canals are recognized as a common feature of germline cells, they are not restricted to the germline. However, there is scant information on the prevalence, function or molecular makeup of ring canals in somatic cells. Aim three begins to address this dearth of information with the analysis of ring canals connecting somatic follicle cells in egg chambers. Genetic analysis will be carried out on a follicle cell ring canal protein identified in a protein-trapping screen. A phenotype associated with loss of follicle cells ring canals will likely provide the first insight into their function in epithelial cells.