GROWTH/DIFFERENTIATION FACTORS IN ORGANOGENESIS

器官发生中的生长/分化因素

• 批准号: 6289073
• 负责人: ALAN PERANTONI
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6289073
• 关键词: carcinogenesis; cell differentiation; developmental genetics; fibroblast growth factor; growth factor receptors; hepatocyte growth factor; histogenesis; kidney neoplasms; mitogens; oncoproteins; renal glomerulus; renal tubule; tissue /cell culture

Morphogenesis and stem cell fate determination are directed by a complex of soluble factors and extracellular matrix interactions in organogenesis. While many of these factors have been defined, there is no comprehensive understanding of the specific molecules that mediate differentiation in any given tissue, the responses that each factor elicits, or the sequence of events required for proper patterning. Accordingly, we have developed in vitro systems for producing and purifying the inductive factors that direct kidney development and for analyzing molecular responses in renal tissues to this induction. Previously, we established a cell line from the ureteric bud epithelium, the renal inductive tissue and precursor for the collecting duct in the adult. These cells grow in a defined medium and secrete a tubule-inducing/inductive activity for metanephric mesenchyme. The inductive factor(s) produced by these cells can be collected from conditioned medium, and one of these has recently been purified. This protein has been shown to mediate both the early events of nephrogenesis, i.e., condensation of mesenchyme and upregulation of wt1, as well as late events, i.e., tubulogenesis and upregulation of lim-1. A second factor, which accelerates tubulogenesis in combination with the first, is also suggested from the purification. As an extension of this work, we have also initiated efforts to characterize events downstream of inductive signaling and specifically those associated with the epithelial conversion of metanephric mesenchyme. For this, we previously showed that Fgf2 can mediate condensation but not tubule formation in explant culture, while Fgf2 in combination with our bud cell line-derived activity can induce complete nephrogenesis. The differences have provided the basis for a direct evaluation of the genes responsible for morphogenesis using differential display methodologies. Tubulogenesis is completed over a 3-day period, so molecular events were evaluated by processing explants after 6, 24, and 72 hrs. Using this approach, we have identified 72 cDNA species, which are specifically regulated in this process, 36 of which are novel. These studies have identified certain signaling pathways that mediate the inductive response and include growth factors, cell-cycle regulatory proteins, protein kinases involved in signal transduction pathways, calcium-binding proteins, transcription factors, and proteins associated with cell adhesion. A picture is gradually emerging from these studies of the specific molecular events that mediate tubule formation downstream from the initiating inductive process. Since the epithelial conversion of metanephric mesenchyme is believed to be targeted in nephroblastic tumorigenesis, causing the accumulation of blastemal stem cells, these studies should provide clues as to the molecular lesions which allow that to occur. - Cell signaling, Kidney, Differentiation, Growth factors, Induction, Organogenesis, Wilms' tumors, Childhood tumors,

形态发生和干细胞命运决定是由器官发生中可溶性因子和细胞外基质相互作用的复合体指导的。虽然其中许多因素已经被定义，但对于介导任何给定组织中分化的特定分子、每个因素引起的反应或正确模式所需的事件顺序还没有全面的了解。因此，我们开发了体外系统，用于产生和纯化指导肾脏发育的诱导因子，并分析肾组织对此诱导的分子反应。此前，我们从成人输尿管芽上皮、肾诱导组织和集合管前体中建立了细胞系。这些细胞在确定的培养基中生长并分泌后肾间质的小管诱导/诱导活性。这些细胞产生的诱导因子可以从条件培养基中收集，其中之一最近已被纯化。该蛋白已被证明可以介导肾发生的早期事件，即间充质的浓缩和 wt1 的上调，以及晚期事件，即肾小管发生和 lim-1 的上调。纯化过程还表明了第二个因素，它与第一个因素结合加速了肾小管的形成。作为这项工作的延伸，我们还开始努力描述诱导信号下游的事件，特别是那些与后肾间质上皮转化相关的事件。为此，我们之前表明，Fgf2 可以介导外植体培养中的凝缩，但不能介导肾小管形成，而 Fgf2 与我们的芽细胞系衍生的活性相结合可以诱导完整的肾发生。这些差异为使用差异显示方法直接评估负责形态发生的基因提供了基础。管发生在 3 天的时间内完成，因此通过在 6、24 和 72 小时后处理外植体来评估分子事件。使用这种方法，我们已经鉴定了 72 个 cDNA 物种，它们在此过程中受到专门调控，其中 36 个是新的。这些研究已经确定了介导诱导反应的某些信号传导途径，包括生长因子、细胞周期调节蛋白、参与信号转导途径的蛋白激酶、钙结合蛋白、转录因子和与细胞粘附相关的蛋白质。从这些对介导起始诱导过程下游小管形成的特定分子事件的研究中，一幅图景逐渐浮现出来。由于后肾间充质的上皮转化被认为是肾母细胞肿瘤发生的目标，导致胚芽干细胞的积累，因此这些研究应该为导致这种情况发生的分子病变提供线索。 - 细胞信号传导、肾脏、分化、生长因子、诱导、器官发生、肾母细胞瘤、儿童肿瘤、