Control of epithelial morphogenesis in Drosphila ovary

描述（由申请人提供）：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阐明。这些知识对于理解生殖生物学和病理学至关重要。例如，卵巢表面上皮中上皮粘附连接的丧失与侵袭性卵巢癌的发病有关。在果蝇卵室中，多种上皮功能由单层滤泡细胞承担。这为分析卵泡上皮细胞的发育及其对卵母细胞发育的影响提供了一个非常可行的模型。在我们以前的研究表皮生长因子受体（EGFR）信号，指定滤泡细胞的命运，我们确定了果蝇同源的冯希佩尔-林道肿瘤抑制基因（VHL）作为EGFR信号的调节剂。更深入的研究表明，VHL在组织滤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，观察到三种不同的表型：1）由EGFR错误定位引起的典型腹型表型; 2）与整联蛋白突变引起的表型相似的矮胖表型;和3）退化的卵室表型与多层上皮和粘附连接的破坏有关。因此，VHL可能是协调基底粘附（整合素）和顶侧（粘附）连接的中枢组织活动。我们还发现，VHL蛋白可以直接相互作用，在体内和体外，与同源的假定的人类转移抑制剂nm 23。提出了一个研究滤泡上皮形成的工作模型，重点研究这两个肿瘤相关基因的功能。目的1：阐明VHL与nm 23/Awd的功能关系。目的2：探讨EGFR在DVHL突变体中的错误定位机制。目的3：分析Rac在连接整合素和DE-cadherin功能中的作用。目的4：分离新的DVHL和新的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.