Cell Signaling in Developing Epithelia

上皮细胞的分化、生长和维持对所有多细胞生物体的正常发育和生理至关重要。在胚胎发育过程中控制增殖和分化的许多相同的蛋白质也与疾病的发病机制有关。这项建议将集中在细胞-细胞信号机制，调节上皮细胞的分化和复杂组织的模式，上皮细胞和 间充质成分。我们已经确定了一种新的小鼠基因，称为KCP1，它编码的蛋白质与分泌信号肽的转化生长因子-β超家族的调节因子具有同源性。KCPI是一个含有19个重复的富含半胱氨酸结构域的大分泌蛋白，可能与转化生长因子-β家族的配体直接结合。KCP1在发育的早期和晚期都有表达，与中间中胚层上皮结构的形成和较发达的后肾肾中近端小管的形成相对应。表达模式和氨基酸序列表明，KCPI可能影响BMP或转化生长因子-β信号，这两种信号都被认为调节肾脏上皮的分化和成熟。我们还鉴定了KCP1的一个果蝇同源基因，它在早期胚胎和后期胚胎发生的上皮衍生品中表达。我们将采取多方面的方法来了解KCP1在小鼠和 果蝇，果蝇。功能丧失的小鼠突变将决定成人肾脏和肾脏疾病模型对KCP1的需求。用小鼠KCP1和果蝇cv-2基因进行的功能获得实验将解决生化作用机制，并使我们能够将该基因置于信号通路中。KCP1的功能与旨在研究蛋白质-蛋白质相互作用和下游信号传导的体外实验相结合 将会被确定。使用在苍蝇中开发的强大的遗传分析以及从小鼠身上开发的生化和遗传工具，这一提议将显著影响我们对BMP和转化生长因子-β信号如何定位和调节受体相互作用的理解。转化生长因子-β信号通路与肾纤维化的发生和发展有关，而肾纤维化是慢性肾脏疾病的共同病理基础。更新的证据 指出转化生长因子-β介导的肾上皮细胞向间质成纤维细胞的转分化是疾病进展的重要组成部分。这些研究将为了解转化生长因子-β分泌肽家族在正常和病变肾上皮细胞中的生物学功能提供新的基础，从而为潜在的临床应用提供必要的机制背景。

Differentiation, growth, and maintenance of epithelial cells are of fundamental importance to normal development and physiology of all multi-cellular organisms. Many of the same proteins that control proliferation and differentiation during embryonic development also contribute to the pathogenesis of disease. This proposal will focus on cell-cell signaling mechanisms that regulate the differentiation of epithelia and the patterning of com plex tissues with both epithelial and mesenchymal components. We have identified a new mouse gene, called KCP1, that encodes a protein with homology to regulators of the TGF-beta superfamily of secreted signaling peptides. KCPI is a large secreted protein with 19 repeated cysteine-rich domains, which may bind to the TGF-beta family of ligands directly. KCP1 is expressed in the developing kidney at both early and late stages and corresponds to the formation of epithelial structures within the intermediate mesoderm and to the formation of the proximal tubules in the more developed metanephric kidney. The pattern of expression and the amino-acid sequence suggest that KCPI may affect BMP or TGF-beta signaling, both of which are known to regulate epithelial differentiation and maturation in the kidney. We have also identified a Drosophila orthologue of KCP1 that is expressed in the early embryo and in epithelial derivatives during later embryogenesis. We will take a multi-faceted approach to understand the biological role of KCP1 in the mouse and in the fruit fly, Drosophila. Loss-of-function mouse mutants will determine the requirements for KCP1 in adult kidneys and in renal disease models. Gain-of-function experiments with both mouse KCP1 and the Drosophila cv-2 gene will address the biochemical mechanisms of action and enable us to place this gene into a signaling pathway. Together with in vitro assays designed to examine protein-protein interactions and downstream signaling, the function of KCP1 will be determined. Using the powerful genetic assays developed in the fly and biochemical and genetic tools from the mouse, this proposal will significantly impact our understanding of how BMP and TGF-beta signals are localized and regulated with respect to receptor interactions. The TGF-b signaling pathways are implicated in the initiation and progression of renal fibrosis a common pathological denominator in chronic renal disease. More recent evidence points to TGF-beta mediated transdifferentiation of renal epithelia to interstitial fibroblasts as an important component of disease progression. These studies will provide fundamental new insight into the biological functions of the TGF-beta family of secreted peptides in normal and diseased renal epithelia and thus provide the necessary mechanistic background for potential clinical applications.