Control of cell rearrangement

描述(申请人提供)：在胚胎发生过程中，细胞重排比任何其他过程都更多地引起形态发生(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(细胞膜)的定向重排对于一些不同的管状器官的伸长是必不可少的，例如肠道和肾脏。果蝇的后肠在许多特征上与脊椎动物的结肠同源，是研究上皮细胞重排的优秀遗传模型。我们已经定义了一个转录调控层次结构，它建立了后肠的前域，并表明在果蝇的这个区域中表达JAK/STAT通路的配体是定向细胞重排所必需的。最近，我们已经证明了Rho家族中的一个小GTP酶，Rac，是后肠细胞重排所必需的。我们建议在高分辨率下表征细胞重排，特别是在固定的和活的野生型和Rac突变胚胎中重排细胞之间的突起。我们的可检验假设是，通过特定的GEF对RAC活性的空间定位调制，以及激活的RAC与特定靶点的相互作用，是促进细胞形状和运动性的变化，从而促进后肠中的内侧细胞插入所必需的。在拟议的分析中，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挽救RAC突变的后肠表型，来鉴定和表征这些RAC在后肠中的相互作用。这将提供一个独特的，在体内理解定向细胞重排的分子基础。在这项工作的过程中，我们将产生多种基因工程果蝇品系，这将使器官发生分析的新方法成为可能。这项工作，通过提供对细胞重排和小管延长的洞察，对癌症治疗和组织工程都有重要的意义。

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.