Modulation of TGF-beta signalling

所有的器官和组织都有结缔组织的框架，结缔组织为它们提供结构和机械支撑。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。成纤维细胞对环境中的多种细胞因子和生长因子做出反应。在完整的器官中，成纤维细胞对转化生长因子-1(转化生长因子-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，转化生长因子-1促进成纤维细胞向肌成纤维细胞的转变，这是组织修复所必需的过程。因此，成纤维细胞对转化生长因子1的反应是所有生物体器官维护和修复的关键。在哺乳动物中，已知有三种转化生长因子受体。转化生长因子受体I型(T？RI型)和II型(TRII型)激活了几个信号级联反应，以响应该细胞因子。细胞通过内化这些受体(即内吞作用)来调节转化生长因子受体的活性，随后可以循环到质膜，或通过降解。我们的总体和长期目标是阐明转化生长因子受体信号是如何被调节的。重要的是，尽管它很重要，但在理解TüRII的调节机制以及TüRII结合蛋白在内吞、运输以及最终通过该受体传递信号中所起的作用方面仍然存在关键的差距。例如，尽管TüRII在20年前被首次克隆，但如果它与蛋白质相互作用，则还没有系统的、大规模的蛋白质组学分析的报道。我们对当前提议的工作假设是，rac1和TüRII相互作用的蛋白质通过调节其特定的内吞和运输途径来调节该受体的信号传递，使其走向循环或降解。为了验证这一假说，我们将解决以下短期目标：(1)确定Rac1调节T？RII的机制；(2)通过蛋白质组学方法，鉴定参与T？RII内化和运输的T？RII相互作用蛋白。我们的研究将为从哺乳动物到无脊椎动物的多细胞生物提供对发育、功能和修复至关重要的信号通路的调控。此外，这项研究将有助于培训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，并辅之以对培养细胞的研究，以了解相关的分子机制，以及蛋白质组学。

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.