Control of cell rearrangement

描述（由申请人提供）：细胞重排在胚胎发生期间比任何其他过程引起更多的形态发生（形状）变化，并且是肿瘤细胞转移的关键组成部分。细胞与上皮（细胞片）的定向重排对于许多不同管状器官（如肠和肾）的伸长至关重要。果蝇后肠在许多特征上与脊椎动物结肠同源，是研究上皮细胞重排的极好遗传模型。我们已经定义了一个转录调控层次，建立前域的后肠，并已表明，在这个领域的果蝇配体的JAK/STAT途径的表达是必需的定向细胞重排。最近，我们已经证明，Rho家族的小GTP酶，Rac，是后肠细胞重排所需的。我们建议，在高分辨率，细胞重排的特点，特别是重排细胞之间的突起，在固定和生活，野生型和Rac突变胚胎。我们的可检验的假设是，空间定位的调节Rac活性通过特定的GEF，和相互作用的活化的Rac与特定的目标，是需要促进细胞的形状和运动的变化，从而在后肠中的中外侧细胞嵌入。在所提出的分析中，我们将通过候选基因的功能丧失遗传分析以及通过筛选用于拯救Rac突变后肠表型的新型表达文库来鉴定和表征后肠中的这些Rac相互作用物。这将提供一个独特的，在体内的定向细胞重排的分子基础的理解。在这项工作的过程中，我们将产生多个基因工程果蝇菌株，将允许新的方法来分析器官发生。这项工作，通过提供深入了解细胞重排和小管伸长，对癌症治疗和组织工程具有重要意义。

DESCRIPTION (provided by applicant): Cell rearrangement is responsible for more morphogenetic (shape) changes during embryogenesis than any other process, and is a key component of tumor cell metastasis. Oriented rearrangement of cells with an epithelium (cell sheet) is essential for elongation of a number of different tubular organs, such as gut and kidney. The Drosophila hindgut, homologous in many features to the vertebrate colon, is an excellent genetic model in which to study epithelial cell rearrangement. We have defined a transcriptional regulatory hierarchy that establishes the anterior domain of the hindgut, and have shown that expression in this domain of the Drosophila ligand for the JAK/STAT pathway is required for oriented cell rearrangement. Most recently, we have demonstrated that one of the Rho-family small GTPases, Rac, is required for hindgut cell rearrangement. We propose to characterize, at high resolution, cell rearrangement, particularly the protrusions between rearranging cells, in both fixed and living, wild-type and Rac mutant embryos. Our testable hypothesis is that spatially localized modulation of Rac activity via specific GEFs, and interaction of activated Rac with specific targets, is required to promote changes in cell shape and motility, and thereby mediolateral cell intercalation, in the hindgut. In the proposed analysis, we will identify and characterize these Rac-interactors in the hindgut by lossof- function genetic analysis of candidate genes, and by screening of a novel expression library for rescue of the Rac mutant hindgut phenotype. This will provide a unique, in vivo understanding of the molecular basis of oriented cell rearrangement. In the course of this work we will generate multiple genetically engineered Drosophila strains that will allow novel approaches to the analysis of organogenesis. This work, by providing insight into both cell rearrangement and tubule elongation, has important implications for both cancer therapy and tissue engineering.