Extracellular Matrix Modulation of Cell Phenotype

描述（由申请人提供）：细胞外基质（ECM）通过其在组织结构中的作用以及对细胞生长、迁移和分化的刺激作用，对细胞决策至关重要。ECM信号的传递由整合素受体完成，整合素受体将ECM连接到肌动蛋白细胞骨架并激活各种信号通路。要了解细胞如何协调细胞外信号与细胞内过程，需要深入了解ECM的组成和组织，以及有关响应细胞-ECM相互作用的细胞内分子的信息。我们正在通过分析秀丽隐杆线虫的性腺生成来接近这些问题。秀丽隐杆线虫雌雄同体性腺的形成发生在孵化后，依赖于两个远端尖端细胞（dtc）沿着体壁基底膜基质的迁移。在全基因组筛选中，我们确定了99个参与这一过程的基因。在这里，我们将重点关注几个在DTC迁移起始和DTC转向形成U形性腺臂中起关键作用的基因。保守基底膜蛋白乳头蛋白（ppn-1）的缺失导致DTC迁移完全受阻。组织分布、表达的时间和调控、突变体的拯救和蛋白域的表达将被用来定义乳头蛋白在性腺形成中的作用。乳头蛋白定位和功能的补充体外研究将使用同样表达该基因的人乳腺上皮细胞进行。为了确定dtc如何与基底膜相互作用，我们将鉴定秀丽隐杆线虫整合素受体介导迁移的ECM配体。在促性腺生成过程中，ECM指导细胞转向和伴随的细胞极性变化，这一过程依赖于两个新基因和pat-2整合素的表达。对这些基因的功能分析和迁移dtc的延时视频显微镜将确定转向的分子要求。这些目标的结果将提供关于细胞- ecm相互作用在组织形态发生过程中细胞重排和迁移中的调节作用的新信息。

DESCRIPTION (provided by applicant): The extracellular matrix (ECM) is critical for cellular decision-making through its role in tissue architecture and its stimulatory effects on cell growth, migration, and differentiation. Transmission of ECM signals is carried out by integrin receptors that link the ECM to the actin cytoskeleton and activate various signaling pathways. To understand how cells coordinate extracellular signals with intracellular processes requires insights into the composition and organization of the ECM as well as information about the intracellular molecules that respond to cell-ECM interactions. We are approaching these questions by analyzing gonadogenesis in the nematode Caenorhabditis elegans. Formation of the C. elegans hermaphrodite gonad occurs after hatching and depends on migration of two distal tip cells (DTCs) along the body wall basement membrane matrix. In a genome-wide screen, we identified 99 genes that are required for this process. Here we will focus on several of those genes that play critical roles in initiation of DTC migration and in DTC turning to form the U- shaped gonad arms. Loss of the conserved basement membrane protein papilin (ppn-1) causes a complete blockade of DTC migration. Tissue distribution, timing and regulation of expression, rescue of mutants, and expression of protein domains will be used to define papilin's role in gonad formation. Complementary in vitro studies of papilin localization and function will be performed using human mammary epithelial cells which also express this gene. To determine how DTCs interact with basement membranes, we will identify the ECM ligands for the C. elegans integrin receptors that mediate migration. The ECM directs cell turning and accompanying changes in cell polarity, processes that are dependent on two novel genes and on expression of the pat-2 integrin during gonadogenesis. Functional analyses of these genes and time-lapse video microscopy of migrating DTCs will define molecular requirements for turning. Results from these aims will provide novel information about the regulatory role of cell-ECM interactions in cell rearrangements and migration during tissue morphogenesis. Public Health Relevance: Progression of most, if not all, human diseases is facilitated by perturbations in the extracellular matrix, the network of proteins and carbohydrates that surrounds cells. The extracellular matrix plays essential roles in organizing cells into tissues and controlling organ function. The proposed studies will provide novel information about how changes in cell connections to the extracellular matrix affect organ development and will provide new ideas about how alterations in extracellular matrix contribute to human disease.