Competition and morphogenesis in tip cell-mediated branching of tubular networks

尖端细胞介导的管状网络分支的竞争和形态发生

• 批准号: 7984881
• 负责人: AMIN S GHABRIAL
• 金额: $ 29.9万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7984881
• 关键词: Affect; Age related macular degeneration; Animal Model; Biological Assay; Biological Models; Blood Vessels; Cell Adhesion; Cell Shape; Cells; Coronary Arteriosclerosis; Coupled; Defect; Disease; Drosophila genus; Endothelial Cells; Environment; Epithelium; Fibroblast Growth Factor; Fibroblast Growth Factor Receptors; Filopodia; Genes; Genetic; Genetic Epistasis; Goals; Homologous Gene; Homozygote; Human; Intercellular Junctions; Lateral; Lead; Life; Ligands; Malignant Neoplasms; Measures; Mediating; Modeling; Molecular; Molecular Genetics; Morphogenesis; Mus; Mutation; Names; Nematoda; Organ; Pathway interactions; Pattern; Play; Positioning Attribute; Process; Protein Tyrosine Kinase; Proteins; Receptor Protein-Tyrosine Kinases; Receptor Signaling; Relative (related person); Role; Septate; Series; Shapes; Side; Signal Pathway; Signal Transduction; Stream; Stroke; System; Testing; Tight Junctions; Tissues; Trachea; Translating; Tube; Tubular formation; Vascular Endothelial Growth Factor Receptor; Vascular Endothelial Growth Factors; Vascular System; angiogenesis; base; cell behavior; cell motility; cellular imaging; migration; mutant; notch protein; novel; public health relevance; research study; respiratory; response; transcription factor

DESCRIPTION (provided by applicant): A critical mechanism for generating new branches in the human vascular system is sprouting. In sprouting angiogenesis, endothelial cells from a pre-existing tube are led by actively migrating "tip cells" to form new vessels. Similarly, in the Drosophila respiratory organ (tracheal system), primary branching occurs through a sprouting mechanism in which tip cells play the same essential role. In both models of branch sprouting, the tip cells are morphologically distinct, extending filopodia to sense the local environment and to lead migration up a concentration gradient of a branch-inducing signal (Vascular endothelial growth factor/VEGF and fibroblast growth factor/FGF, respectively). We have shown that tracheal cells compete with each other for tip cell positions in Drosophila, where competition is based on relative levels of FGF Receptor (FGFR) activity and is mediated in part by the lateral inhibitory signal Notch. If Notch signaling is abrogated, a vast excess of tip cells are selected and migrate to the leading end of the sprout while only one or two follower cells comprise the branch stalk. Competition for tip cell positions also occurs during sprouting angiogenesis, with Receptor Tyrosine Kinase (RTK) and Notch signaling playing the same key roles. Despite substantial progress in understanding tip cell selection, the direct targets of Notch signaling that antagonize tip cell behavior in stalk cells remain unknown. Likewise, while RTK signaling promotes tip cell migration, the direct targets of the RTKs in tracheal and endothelial tip cells are not known. We have identified a novel mutation that we have named too many leaders, that confer a tip cell bias to mutant cells, and mutations in the septate/tight junction gene polychaetoid/ZO-1, that confer a Notch-like extra tip cell defect. We propose that tracheal tip cells and endothelial tip cells are selected by a conserved competition-based mechanism, and will systematically dissect the signaling pathways and their downstream targets, with the goal of determining how signaling information is translated into changes in cell shape, cell position within an epithelium, and cell migration, such that a pre- existing tube reorganizes to sprout a side branch. The specific aims of this project are: 1. To define the RTK core components that mediate tip cell selection, and to determine whether a transcriptional response to RTK signaling is required. 2. To determine how Notch signaling is regulated and transduced during branch sprouting, and to examine how selective loss of Notch ligand expression affects tip cell competition. 3. To test the hypothesis that Polychaetoid and Too Many Leaders are downstream effectors of Notch signaling during tip cell competition. PUBLIC HEALTH RELEVANCE: Angiogenesis-dependent diseases - including age-related macular degeneration, coronary artery disease, stroke, and cancer - result when new blood vessels either grow excessively or insufficiently. New branches in the human vascular system are generated by a process called sprouting angiogenesis, in which endothelial cells from a pre-existing tube are led by actively migrating "tip cells" to form new vessels. This proposal aims to use Drosophila tracheal branching as a model to uncover the genetic and molecular mechanisms by which tip cells are selected and by which they lead outgrowth of new tubes.

描述（由申请人提供）：在人体血管系统中产生新分支的关键机制是出芽。在萌芽血管生成中，来自预先存在的管的内皮细胞被主动迁移的“尖端细胞”引导以形成新的血管。类似地，在果蝇的呼吸器官（气管系统）中，初级分支通过芽生机制发生，其中尖端细胞发挥同样重要的作用。在两种分支发芽模型中，尖端细胞在形态上是不同的，延伸丝状伪足以感知局部环境并导致分支诱导信号（分别为血管内皮生长因子/VEGF和成纤维细胞生长因子/FGF）的浓度梯度向上迁移。我们已经表明，气管细胞相互竞争的尖端细胞的位置在果蝇，竞争是基于FGF受体（FGFR）的活性的相对水平，并介导的部分由侧抑制信号Notch。如果Notch信号传导被废除，大量过量的顶端细胞被选择并迁移到芽的前端，而只有一个或两个跟随细胞构成分支茎。尖端细胞位置的竞争也发生在萌芽血管生成期间，受体酪氨酸激酶（RTK）和Notch信号传导起着相同的关键作用。尽管在理解尖端细胞选择方面取得了实质性进展，但在柄细胞中拮抗尖端细胞行为的Notch信号传导的直接靶点仍然未知。同样，虽然RTK信号传导促进尖端细胞迁移，但气管和内皮尖端细胞中RTK的直接靶点尚不清楚。我们已经确定了一种新的突变，我们已经命名了太多的领导人，赋予突变细胞的尖端细胞偏好，以及隔膜/紧密连接基因多毛类/ZO-1的突变，赋予Notch样额外的尖端细胞缺陷。我们提出，气管尖端细胞和内皮尖端细胞是通过保守的基于竞争的机制选择的，并且将系统地剖析信号传导通路及其下游靶点，目的是确定信号传导信息如何转化为细胞形状、上皮内细胞位置和细胞迁移的变化，使得预先存在的管重组以萌发侧分支。该项目的具体目标是：1。定义介导尖端细胞选择的RTK核心组件，并确定是否需要对RTK信号传导的转录应答。 2.确定Notch信号在分支发芽过程中是如何调节和转导的，并检查Notch配体表达的选择性丧失如何影响尖端细胞竞争。 3.为了检验在尖端细胞竞争期间多毛类和太多前导是Notch信号传导的下游效应物的假设。 公共卫生关系：血管生成依赖性疾病--包括年龄相关性黄斑变性、冠状动脉疾病、中风和癌症--是新血管过度生长或生长不足的结果。人类血管系统中的新分支是通过一种称为萌芽血管生成的过程产生的，其中来自预先存在的管道的内皮细胞在积极迁移的“尖端细胞”的引导下形成新血管。该建议旨在使用果蝇气管分支作为模型，以揭示尖端细胞被选择并导致新管生长的遗传和分子机制。