Control of epithelial morphogenesis in Drosphila ovary

描述(申请人提供)：卵巢发育是一个需要生殖系(卵母细胞)及其周围体细胞协调生长和分化的过程。在哺乳动物中，体细胞卵泡细胞的多细胞层用于直接与卵母细胞沟通，与细胞外基质相互作用，并支持卵泡的物理完整性。因此，上皮完整性在卵巢发育中起着不可或缺的作用，尽管其潜在的细胞和分子机制尚未被阐明。这些知识对于理解生殖生物学和病理学都是至关重要的。例如，卵巢表面上皮细胞上皮黏附连接的缺失与侵袭性卵巢癌的发生有关。在果蝇卵室中，多种上皮功能由单层滤泡细胞承担。这为分析卵泡上皮发育及其对卵母细胞发育的影响提供了一个非常方便的模型。在我们以前对决定滤泡细胞命运的EGF受体(EGFR)信号的研究中，我们发现了von Hippel-Lindau肿瘤抑制基因(VHL)的果蝇同源基因是EGFR信号的调节器。更深入的研究表明，VHL在组织卵泡上皮的极性和完整性方面发挥了更大的作用。在VHL敲除突变体中，观察到了三种不同的表型：1)典型的由EGFR错位引起的腹腔化表型；2)与整合素突变相似的短脂肪表型；以及3)与上皮多层和贴壁连接破裂相关的退化卵室表型。因此，VHL可能是一种协调基础粘连(整合素)和顶侧(粘连)连接的中枢组织活动。我们还发现，VHL蛋白在体内和体外都可以与假定的人类转移抑制因子nm23的同源物直接相互作用。提出了一个研究卵泡上皮形成的工作模型，重点研究了这两个肿瘤相关基因的功能。目的1：阐明VHL与nm23/AWD的功能关系。目的：探讨表皮生长因子受体在DVHL突变体中定位错误的可能机制。目的：分析Rac在连接整合素和DE-钙粘附素功能中的作用。目的4：分离新的DVHL和AWD相互作用蛋白。

DESCRIPTION (provided by applicant): Ovarian development is a process that requires coordinated growth and differentiation of the germline (oocyte) and its surrounding somatic cells. In mammals, multicellular layers of somatic follicle cells serve to communicate directly with the oocyte, to interact with the extra-cellular matrix, and to support the physical integrity of the follicle. Epithelial integrity therefore plays an integral role in ovary development although the underlying cellular and molecular mechanisms have yet to be elucidated. Such knowledge is critical for understanding reproductive biology as well as pathology. For example, loss of epithelial adherens junctions in the ovarian surface epithelium has been implicated in the onset of invasive ovarian cancer. In Drosophila egg chambers, the multiple epithelial functions are assumed by a single layer of follicle cells. This provides a very accessible model for analyzing the follicular epithelial development and its influence on the oocyte development. In our previous studies on the EGF receptor (EGFR) signaling that specifies the follicular cell fates, we identified the Drosophila homolog of the von Hippel-Lindau tumor suppressor gene (VHL) as a modulator of EGFR signaling. More in-depth studies revealed that VHL played a much larger role in organizing the polarity and integrity of the follicular epithelium. In the VHL knock-down mutant, three distinct phenotypes are observed: 1) A typical ventralized phenotype resulting from mislocalized EGFR; 2) A short-and-fat phenotype similar to that caused by integrin mutations; and 3) A degenerated egg chamber phenotype associate with multilayering of the epithelium and breakdown of the adherens junctions. Thus, VHL is potentially a central organizing activity that coordinates the basal adhesion (integrin) and apicolateral (adherens) junctions. We have also found that the VHL protein can interact directly, both in vivo and in vitro, with the homolog of the putative human metastasis inhibitor nm23. A working model is proposed to study the formation of follicular epithelium, focusing on the functions of these two tumor-related gene function. Four specific Aims are designed: Aim 1: To elucidate the functional relationship between VHL and nm23/Awd. Aim 2: To determine the underlying mechanism of EGFR mislocalization in DVHL mutant. Aim 3: To analyze the role of Rac in linking integrin and DE-cadherin functions. Aim 4: To isolate additional DVHL and novel Awd interacting protein.