Morphogenesis: Biophysics and Genetics of Dorsal Closure

细胞片层形态发生对于后生动物的发育和动物形态的稳态是必不可少的--它有助于 发育，如原肠胚形成、神经管、心脏和腭的形成，以及创伤中的稳态， 治愈基因表达和信号级联协调和调节细胞机器， 形态发生这些组成部分的功能障碍会导致发育和伤口愈合缺陷， 毁容或杀人我们专注于背侧闭合（DC）过程中细胞片层形态发生的分子机制 在黑腹果蝇中在DC期间，侧表皮片推进以关闭背侧开口。我们 开创了DC作为模型系统的研究，并使用跨学科的异常多样化的剧目， 方法，包括现场成像，反向和正向遗传学和生物物理策略，以询问 机制和野生型和突变体胚胎的关闭调节。我们发现，DC是四个主要参数之和 动态过程，并且是稳健和有弹性的-没有单一的力量，驱动关闭是绝对必要的。 在分子、细胞和组织尺度上促进DC的过程在动物中高度保守 果蝇的形态发生使其成为探究形态发生的分子基础的理想模型系统。 我们对这种概念上简单但生物学上复杂的细胞的理解仍然存在重大差距 板材运动为了鉴定新的"DC基因"，即，当这些基因被删除时，会破坏闭合， 基因，实时成像，屏幕该屏幕使用了194个缺陷库存（Dfs），这些库存总共删除了5，778个 黑腹果蝇的第二条染色体上有5,854个基因。我们已经开始将筛选范围扩大到第三条染色体。 值得注意的是，96 Dfs造成了明显的和不同的缺陷，关闭，表明大量的离散 生物过程有助于闭合，并且容易受到突变破坏。到目前为止， 鉴定了13个新的前DC或DC基因，它们负责DC Df表型。当扩展到整个 我们的筛选预计将鉴定出~165个新的DC基因（最初仅知道~140个DC基因 我们的屏幕）。基于表型，我们优先考虑要关注的DC Dfs，确定负责的DC基因， 对于它们的Df表型，然后表征新的DC基因产物如何有助于闭合。应重点 了解细胞间相互作用和细胞基质粘附耦合的分子机制， 肌动球蛋白细胞骨架-这些连接必须足够坚固，以传递力，但有足够的延展性 以允许细胞形状的改变来定义形态发生。更令人感兴趣的是一项新的努力， 从分子动力学和动力学上表征了在DC和其他细胞中驱动形态发生的肌球蛋白2马达 发展过程。我们的目标是评估编码肌球蛋白运动域的差异剪接 作为快速移动、缓慢/有效的力保持、应变感测或进行性运动，有助于形态发生。 我们处于独特的地位，以解决基础生物学的分子和生物物理机制 果蝇细胞片层形态发生的研究，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.