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

该提案的目的是揭示调节心脏等器官发育和重塑的细胞与细胞外基质（ECM）相互作用的机制。ECM是糖蛋白和蛋白聚糖的网络，其是承受细胞和组织张力的底物，其还保护组织并提供指导细胞行为的分子来源。 在这里，我提出的实验来测试的假设，粘附信号的通信信息，修改的组成，空间组织和物理特性的本地ECM。我的项目采用果蝇心脏作为具有简单形态的遗传模型，并专注于在整个发育和衰老过程中细胞外消化酶（蛋白酶）对心脏ECM的活性。我们已发表的工作表明，心肌粘附信号的持续变化影响心脏的形式和功能。我们建立了内血管壁的大小和位置由两种基质金属蛋白酶（MMP）的活性调节。这为我们分析ECM组成和组织的变化如何重塑组织形式和功能提供了背景。这项工作支持更深入地了解细胞外机制如何产生形态多样性，并在生长和衰老过程中对外部因素作出反应。 涉及三个目标： 1.揭示ECM蛋白酶如何使心管形成。蛋白质分布表明，每个细胞内的特定信号（细胞内靶向，脂质信号传导和GTP酶信使）差异性地限制于表达钙粘蛋白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的位置是否在这些信号的上游起作用。 2.确定每种细胞类型如何有助于ECM重塑。 我们的初步研究结果揭示了幼虫心脏的ECM和血细胞（血细胞）簇之间的密切联系。血细胞也聚集在心脏的畸形区域。我们将使用遗传工具来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可以告知ECM重塑。果蝇提供了一个独特的模型，其中信号心脏负荷的受体（如整合素），或响应心脏负荷的基因表达可以暂时改变。我们将在心脏中表达转基因，使肌肉效率降低，并抑制ECM结构和成分的变化。此外，我们将确定血细胞或肌肉细胞是否调节这些变化，并探索哪些信号可用于触发反应。

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.