Cell Signaling in Developing Epithelia

上皮细胞的分化、生长和维持对于所有多细胞生物体的正常发育和生理学具有根本重要性。许多在胚胎发育过程中控制增殖和分化的相同蛋白质也有助于疾病的发病机制。该建议将集中于调节上皮细胞分化的细胞间信号传导机制，以及具有上皮和上皮细胞的复杂组织的模式化。 间充质成分我们已经确定了一个新的小鼠基因，称为KCP 1，它编码的蛋白质与分泌信号肽的TGF-β超家族的调节因子具有同源性。KCPI是一种具有19个重复的富含半胱氨酸的结构域的大分泌蛋白，其可以直接结合TGF-β家族的配体。KCP 1在早期和晚期的发育中的肾脏中表达，并且对应于中间中胚层内上皮结构的形成和更发达的后肾中近端小管的形成。表达模式和氨基酸序列表明，KCPI可能影响BMP或TGF-β信号传导，已知这两者都调节肾脏中的上皮分化和成熟。我们还确定了果蝇直系同源的KCP 1，在早期胚胎和上皮衍生物在以后的胚胎发育过程中表达。我们将采取多方面的方法来了解KCP 1在小鼠和哺乳动物中的生物学作用。 果蝇功能丧失小鼠突变体将决定成人肾脏和肾脏疾病模型对KCP 1的需求。用小鼠KCP 1和果蝇cv-2基因进行的功能获得实验将阐明作用的生化机制，并使我们能够将该基因置于信号通路中。结合设计用于检测蛋白质-蛋白质相互作用和下游信号传导的体外试验， 将被确定。使用强大的基因检测开发的苍蝇和生化和遗传工具的小鼠，这一建议将显着影响我们的理解BMP和TGF-β信号是如何定位和调节受体相互作用。TGF-β信号通路参与肾纤维化的发生和发展，肾纤维化是慢性肾脏疾病的常见病理特征。最近的证据 指出TGF-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。这些研究将为正常和患病肾上皮细胞中TGF-β家族分泌肽的生物学功能提供基本的新见解，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.