Biophysical Mechanisms of Drosophila Development.

描述(申请人提供)：多细胞生物体的不同形状是在发育过程中通过细胞形状和行为的空间和时间调节的变化而建立的。在多细胞生物中，一个主要的形态发生运动是细胞的重组，形成细长的头尾体轴。这种保守的过程需要一个惊人的方向性，即细胞群体将它们的运动与身体轴对齐，这被称为细胞嵌入。上皮组织中的细胞嵌入是在细胞重排过程中细胞之间传递机械力并保持其完整性的粘连连接网络的存在下发生的。遗传学研究提供了对调控细胞命运和行为的生化信号的洞察，但对于细胞如何感知和响应机械信号，将机械力转化为细胞定向运动，人们知之甚少。在果蝇胚胎中，驱动体轴延长的极化细胞重排是由收缩肌球蛋白网络的空间和时间调节所指导的。然而，介导力依赖性肌球蛋白调控的分子机制还不是很清楚。这些研究的长期目标是深入了解细胞如何将机械力转化为生化信号，以在发育过程中产生三维组织结构。这项建议的总体目标是描述调控肌球蛋白在嵌入细胞中定位的机械转导途径的分子基础，并研究这一机制如何影响形成果蝇体轴的三维细胞行为。我们将使用我们开发的高通量计算方法来分析在果蝇胚胎中肌球蛋白的体内定位，并将肌球蛋白的动力学与其他参与收缩和细胞黏附的蛋白质的分布进行比较。我们将使用生物物理、现场成像和定量 描述将机械力转化为肌球蛋白定位变化的分子机制的计算方法。此外，我们还将分析细胞在轴伸长过程中的三维形状和行为，并对缺乏特定蛋白质的胚胎的缺陷进行表征。机械力已被证明影响组织发育的许多方面，包括血管重塑、肺分支形态发生以及心脏、肾脏、乳腺和骨骼的发育。这些研究将确定机械力调节肌球蛋白定位和活性的机制，并提供与治疗和预防涉及机械细胞调节缺陷的人类疾病相关的信息，包括动脉粥样硬化、骨质疏松症和肿瘤转移。

DESCRIPTION (provided by applicant): The diverse shapes of multicellular organisms are established during development by spatially and temporally regulated changes in cell shape and behavior. A major morphogenetic movement in multicellular organisms is the reorganization of cells to form the elongated head-to-tail body axis. This conserved process requires a striking directionality in which populations of cells align their movements with the body axes, referred to as cell intercalation. Cell intercalation in epithelial tissues occurs in the presence of a networkof adherens junctions that transmits mechanical forces between cells and maintains its integrity as cells make and break contacts throughout cell rearrangement. Genetic studies have provided insight into the biochemical signals that regulate cell fate and behavior, but much less is known about how cells sense and respond to mechanical signals to translate mechanical forces into directional cell movement. In the Drosophila embryo, the polarized cell rearrangements that drive body axis elongation are guided by the spatial and temporal regulation of contractile actomyosin networks. However, the molecular mechanisms that mediate force-dependent myosin regulation are not well understood. The long-term goal of these studies is to obtain insight into how cells translate mechanical forces into biochemical signals to generate three-dimensional tissue structure during development. The overall objective of this proposal is to characterize the molecular basis of the mechanotransduction pathway that regulates myosin localization in intercalating cells and investigate how this mechanism influences the three-dimensional cell behaviors that shape the Drosophila body axis. We will use high-throughput computational methods we have developed to analyze in vivo myosin localization in the Drosophila embryo and compare myosin dynamics with the distributions of other proteins involved in contractility and cell adhesion. We will use biophysical, live imaging and quantitative computational approaches to characterize the molecular mechanisms that translate mechanical forces into a change in myosin localization. In addition, we will analyze cell shape and behavior in three dimensions during axis elongation and characterize the defects in embryos lacking specific proteins. Mechanical forces have been shown to influence many aspects of tissue development, including blood vessel remodeling, lung branching morphogenesis, and development of the heart, kidney, mammary gland, and bone. These studies will identify the mechanisms by which mechanical forces regulate myosin localization and activity and provide information relevant to the treatment and prevention of human diseases that involve defects in mechanical cell regulation, including atherosclerosis, osteoporosis, and tumor progression to metastasis.