Control of cell rearrangement

描述（由申请人提供）：细胞重排在胚胎发生过程中比任何其他过程都要负责更多的形态发生（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的管状器官（如肠和肾）的伸长是必不可少的。果蝇后肠在许多特征上与脊椎动物的结肠相似，是研究上皮细胞重排的良好遗传模型。我们已经定义了一个转录调控层次结构，建立了后肠的前结构域，并表明果蝇配体的JAK/STAT通路的这一结构域的表达是定向细胞重排所必需的。最近，我们已经证明rho家族的一个小gtp酶Rac是后肠细胞重排所必需的。我们建议在高分辨率下描述细胞重排，特别是重排细胞之间的突起，在固定和活的，野生型和Rac突变胚胎中。我们可验证的假设是，通过特定gef对Rac活性进行空间局部调节，以及活化Rac与特定靶点的相互作用，是促进后肠细胞形状和运动变化的必要条件，从而促进细胞内插。在本研究中，我们将通过对候选基因的功能缺失遗传分析，以及通过筛选新的表达文库来拯救Rac突变后肠表型，来识别和表征后肠中的Rac相互作用物。这将为定向细胞重排的分子基础提供一个独特的、在体内的理解。在这项工作的过程中，我们将产生多种基因工程果蝇菌株，这将为器官发生分析提供新的方法。这项工作，通过提供对细胞重排和小管延伸的洞察，对癌症治疗和组织工程都具有重要意义。

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.