Modulation of TGF-beta signalling

所有器官和组织都有一个结缔组织框架，为它们提供结构和机械支持。结缔组织还提供从血液中扩散营养物质和氧气的途径，并参与损伤后所有器官的再生。 成纤维细胞是结缔组织的主要细胞成分。这些细胞在所有器官的维持和再生中起着关键作用。成纤维细胞在其环境中响应多种细胞因子和生长因子。在完整的器官中，成纤维细胞对转化生长因子-β 1（TGF-β 1）的反应导致这些细胞调节细胞外基质蛋白的产生，这有助于维持器官结构。当器官受损时，TGF-β 1促进成纤维细胞转化为肌成纤维细胞，这是组织修复所必需的过程。因此，成纤维细胞对TGF-β 1的反应是所有生物体中器官维持和修复的关键。 哺乳动物中已知有三种TGF-β受体。I型TGF-β受体（T β RI）和II型TGF-β受体（T β RII）响应于该细胞因子激活几个信号级联。细胞通过内化这些受体（即内吞作用）来调节TGF-β受体活性，随后可再循环至质膜或降解。我们的总体长期目标是阐明TGF-β受体信号传导是如何调节的。值得注意的是，尽管其重要性，但在理解T β RII的调节机制以及T β RII结合蛋白在内吞作用、运输以及最终通过该受体的信号传导中所起的作用方面仍然存在关键差距。例如，尽管TßRII在二十年前首次被克隆，但如果其相互作用蛋白质，则没有系统的大规模蛋白质组学分析报告。 我们对当前建议的工作假设是Rac 1和T β RII相互作用蛋白通过调节该受体的特异性内吞和运输途径来调节该受体的信号传导，从而实现回收或降解。为了验证这一假设，我们将致力于以下短期目标：（1）确定Rac 1调节TßRII的机制，和（2）通过蛋白质组学分析方法鉴定参与TßRII内化和运输的TßRII相互作用蛋白。 我们的研究将提供对信号通路的调节的深入了解，该信号通路对于从哺乳动物到无脊椎动物的多细胞生物的发育，功能和修复至关重要。此外，这项研究将有助于培养几名研究生和本科生，他们将有机会学习生物学研究中最先进的实验方法，包括使用转基因小鼠，并辅以对培养细胞的研究，以了解相关的分子机制和蛋白质组学分析。

All organs and tissues possess a framework of connective tissue, which provides them with structure and serves as mechanical support. Connective tissues also provide routes for diffusion of nutrients and oxygen from the blood, and participate in the regeneration of all organs following injury. Fibroblasts are a major cellular component of connective tissues. These cells play pivotal roles in the maintenance and regeneration of all organs. Fibroblasts respond to multiple cytokines and growth factors in their environment. In intact organs, fibroblast responses to transforming growth factor-ß1 (TGF-ß1) result in modulation of extracellular matrix protein production by these cells, which helps maintain organ structure. When an organ gets damaged, TGF-ß1 promotes the transition of fibroblasts into myofibroblasts, a process essential for tissue repair. Thus, fibroblast responses to TGF-ß1 are key for organ maintenance and repair in all organisms. Three receptors for TGF-ß are known in mammals. The TGF-ß receptors type I (TßRI) and type II(TßRII) activate several signaling cascades in response to this cytokine. Cells regulate TGF-ß receptor activity by internalizing these receptors (i.e. endocytosis), which can be followed by recycling to the plasma membrane, or by degradation. Our overall, LONG-TERM OBJECTIVE is to elucidate how TGF-ß receptor signaling is modulated. Significantly, and in spite of its importance, a critical gap still exists in understanding the regulatory mechanisms of TßRII, and the role that TßRII-binding proteins play in endocytosis, trafficking and, ultimately, signalling through this receptor. For example, although TßRII was first cloned two decades ago, no systematic, large-scale proteomic profiling if its interacting proteins has ever been reported. Our working HYPOTHESIS for the current proposal is that Rac1 and TßRII-interacting proteins regulate signaling of this receptor by modulating its specific endocytic and trafficking pathways towards either recycling or degradation. To test this hypothesis, we will address the following SHORT-TERM AIMS: (1) To determine the mechanisms of TßRII regulation by Rac1, and (2) To identify TßRII-interacting proteins involved in TßRII internalization and trafficking, through proteomic profiling approaches. Our studies will provide insight into the regulation of a signaling pathway that is fundamental for development, function and repair in multicellular organisms, from mammals to invertebrates. In addition, this research will contribute to the training of several graduate and undergraduate students, who will have the opportunity to learn state-of-the-art experimental approaches in biological research, including the use of genetically modified mice, complemented with studies on cultured cells to understand relevant molecular mechanisms, and proteomic profiling.