The role of spatial and temporal regulation of Extracellular Matrix composition by Matrix Metalloproteases during development, growth and aging of the Drosophila heart

这一提议的目的是揭示细胞与细胞外基质(ECM)相互作用的机制，该机制调节心脏等器官的发育和重塑。细胞外基质是由糖蛋白和蛋白多糖组成的网络，它们是承受细胞和组织张力的底物，也保护组织，并提供指导细胞行为的分子来源。在这里，我提议进行实验，以检验这一假设，即附着信号传递的信息改变了局部ECM的组成、空间组织和物理属性。我的项目采用果蝇心脏作为遗传模型，具有简单的形态结构，并关注心脏细胞外消化酶(蛋白酶)在心脏细胞外基质发育和衰老过程中的活性。我们发表的研究表明，心肌黏附信号的持续变化会影响心脏的形态和功能。我们证实，血管内壁的大小和位置受两种基质金属蛋白酶(MMPs)的活性调节。这为我们分析细胞外基质成分和组织的变化如何重塑组织形态和功能提供了背景。这项工作有助于更深入地理解细胞外机制如何在生长和衰老过程中产生多样性的形态和对外部因素的响应。*解决三个目标：*1.揭示细胞外基质蛋白水解酶如何促进心管的形成。蛋白质分布表明，每个细胞内的特定信号(细胞内靶向、脂质信号和GTP酶信使)分别限于表达粘附素的顶膜或表达整合素的顶膜。我们将操纵这些信号在胚胎心脏细胞中的表达或功能，以确定整合素、MMPs或局部ECM的位置是否作用于这些信号的上游。*2.确定每种细胞类型如何促进ECM重塑。我们的初步发现表明，幼虫心脏的ECM与血细胞簇(血细胞)之间存在密切的联系。血细胞也会聚集在心脏的畸形区域。我们将使用基因工具改变血细胞归巢信号或功能，以确定这些细胞是否在ECM重塑中发挥作用。*3.确定心脏生理学是否能影响ECM重塑。果蝇提供了一种独特的模型，在这种模型中，发出心脏负荷信号的受体(如整合素)或对心脏负荷做出反应的基因的表达可以暂时改变。我们将在心脏中表达使肌肉效率降低的转基因，并描述细胞外基质结构和组成的变化。此外，我们将确定血细胞或肌肉细胞是否调节这些变化，并探索可能使用哪些信号来触发反应。

The aim of this proposal is to reveal the mechanisms of cell-to-extracellular matrix (ECM) interaction that regulate development and reshaping of organs like the heart. The ECM is a network of glycoproteins and proteoglycans that are the substrate that bears cell and tissue tension, which also protects tissues and provides a source of molecules that instruct the behavior of cells. Here I propose experiments to test the hypothesis that adhesion signals communicate information that modifies the composition, spatial organisation and physical properties of local ECM. My program employs the fruitfly heart as a genetic model with simple morphology, and focus on the activity of extracellular digestive enzymes (proteases) on cardiac ECM throughout development and aging. Our published works demonstrate that ongoing changes in heart muscle adhesion signaling affect heart form and function. We established that the size and location of the inner vessel wall is regulated by the activity of the two Matrix MetalloProteases (MMPs). This provides the backdrop for our analysis of how changes in ECM composition and organisation remodel tissue form and function. This work supports a deeper understanding of how extracellular mechanisms generate diversity of morphology and respond to external factors during growth and aging.***Three AIMs are addressed:***1. Reveal how ECM proteases enable heart tube formation. Protein distribution suggests that specific signals inside each cell (intracellular targeting, lipid signalling and GTPase messengers) are differentially restricted to Cadherin expressing or Integrin expressing apical membrane. We will manipulate expression or function of these signals in embryonic heart cells to determine whether the location of Integrins, MMPs or local ECM acts upstream of these signals.***2. Determine how each cell type contributes to ECM remodeling. Our preliminary findings revealed a close association between the ECM of the larval heart and clusters of blood cells (haemocytes). Haemocytes also accumulate at malformed regions of the heart. We will use genetic tools to alter haemocyte homing signals or function to determine whether these cells paly a role in ECM remodeling.***3. Determine whether heart physiology can inform ECM remodeling. Drosophila provides a unique model where receptors that signal cardiac load (such as Integrin), or the expression of genes that respond to cardiac load can be temporally altered. We will express transgenes in the heart that make the muscle less efficient, and characterise the changes in ECM structure and composition. Further, we will determine whether haemocytes or muscle cells regulate these changes, and explore what signals may be employed to trigger the response.**