Morphogenesis: Biophysics and Genetics of Dorsal Closure

细胞板的形态发生对后生动物的发育和动物形态的动态平衡是必不可少的-它有助于 对原肠、神经管、心脏和上颚的形成和动态平衡的发育，在伤口 治愈。基因表达和信号级联协调和调节驱动细胞的机器 形态发生。这些成分的功能障碍会导致发育和伤口愈合缺陷， 毁容或杀人。我们主要研究在背部闭合(DC)过程中细胞膜形态发生的分子机制。 在果蝇身上。在DC期间，外侧表皮层向前推进以闭合背部开口。我们 开创了将DC作为模型系统进行研究的先河，并使用了异常多样化的跨学科曲目 方法，包括实时成像，反向和正向遗传学和生物物理策略，以审问 野生型和突变型胚胎闭合的机理和调控。我们发现DC是四个主要因素的总和 动态过程，坚固耐用--绝对不需要任何推动关闭的单一力量。 在分子、细胞和组织尺度上促成DC的过程在动物中高度保守 系统发育使果蝇成为询问形态发生的分子基础的理想模式系统。 在我们对这个概念简单但生物学上复杂的细胞的理解上仍然存在很大的差距 板材移动。为了识别新的“DC基因”，即当被删除时，破坏关闭的基因，我们发起了一个正向 基因，实时成像，屏幕。此筛选使用了194只缺陷股(DFS)，这些股票总共删除了5778只 黑腹蛇的第二条染色体上有5854个基因。我们已经开始将我们的屏幕延伸到第三条染色体。 值得注意的是，96个DFS在关闭中造成了显著和多样的缺陷，表明大量离散的 生物过程有助于封闭，并容易受到突变破坏的影响。到目前为止，我们已经 确定了13个新的DC前或DC前基因，这些基因与DC DF表型有关。当扩展到整体时 苍蝇基因组我们的屏幕预计将识别~165个新的DC基因(最初只知道~140个DC基因 我们的屏幕)。根据表型，我们对DC DFS进行了优先排序，确定了DC相关基因 关于它们的df表型，然后描述新的DC基因产物如何有助于闭合。当务之急是 了解细胞-细胞相互作用和基于细胞-基质的黏附的分子机制 肌动蛋白细胞骨架--这些连接必须足够坚固，能够传递力量，同时又具有足够的延展性 以允许定义形态发生的细胞形状变化。更令人感兴趣的是一项新的努力 驱动DC和其他疾病形态发生的肌球蛋白2马达的热力学和动力学特征 发育过程。我们的目标是评估编码肌球蛋白运动区的差异剪接 作为一种快速移动、缓慢/有效的力保持、应变感应或前进马达，有助于形态发生。 我们在解决构成基本生物学基础的分子和生物物理机制方面具有独特的地位。 果蝇细胞板形态发生的研究，直接影响脊椎动物的发育和伤口愈合。

Cell sheet morphogenesis is essential for metazoan development and homeostasis of animal form – it contributes to development, such as in gastrulation, neural tube, heart and palate formation and to homeostasis, in wound healing. Gene expression and signaling cascades coordinate and regulate the cellular machines that drive morphogenesis. Disfunction in these components causes developmental and wound healing defects that can disfigure or kill. We focus on the molecular mechanisms of cell sheet morphogenesis during dorsal closure (DC) in Drosophila melanogaster. During DC, lateral epidermal sheets advance to close a dorsal opening. We pioneered the study of DC as a model system and use an unusually diverse repertoire of interdisciplinary approaches, including live imaging, reverse and forward genetics and biophysical strategies to interrogate the mechanics and regulation of closure in wild type and mutant embryos. We found that DC is the sum of four major dynamic processes and is robust and resilient – no single force that drives closure is absolutely required. Processes that contribute to DC at the molecular, cellular and tissue scales are highly conserved in animal phylogeny making Drosophila an ideal model system for interrogating the molecular basis of morphogenesis. There remain significant gaps in our understanding of this conceptually simple, yet biologically complex cell sheet movement. To identify new “DC genes”, i.e., genes that when deleted, disrupt closure, we initiated a forward genetic, live-imaging, screen. This screen used 194 deficiency stocks (Dfs) that collectively delete 5,778 of the 5,854 genes on melanogaster's 2nd chromosome. We have begun to extend our screen to the 3rd chromosome. Remarkably, 96 Dfs caused notable and diverse defects in closure, indicating that a large number of discrete biological processes contribute to closure and are susceptible to mutational disruption. Thus far, we have identified 13 new pre-DC or DC genes that are responsible for the DC Df phenotypes. When extended to the whole fly genome our screen is projected to identify ~165 new DC genes (only ~140 DC genes were known at the start of our screen). Based on phenotype, we prioritize the DC Dfs on which to focus, identify the DC genes responsible for their Df phenotypes, then characterize how the new DC gene products contribute to closure. A priority is to understand the molecular mechanisms by which cell-cell interactions and cell-matrix based adhesion couple to the actomyosin cytoskeleton – these connections must be robust enough to transmit forces, yet malleable enough to allow the cell shape changes that define morphogenesis. Of further interest is a new effort to thermodynamically and kinetically characterize the myosin 2 motor that drives morphogenesis in DC and other developmental processes. Our goal is to assess how differential splicing that encodes myosin's motor domain contributes to morphogenesis as a fast moving, slow/efficient force holding, strain sensing, or processive motor. We are uniquely positioned to address the molecular and biophysical mechanisms that underlie the basic biology of cell sheet morphogenesis in flies, research that directly informs vertebrate development and wound healing.