Integrin Function in Cartilage

描述(申请人提供)：该项目的长期目标是确定通过整合素受体产生的信号调节软骨细胞功能的机制。这些研究的总体假设是，软骨细胞外基质(ECM)的变化，包括ECM蛋白片段的产生，可由软骨细胞整合素识别，并启动一系列旨在重塑ECM的事件，但在关节炎中会导致进一步的基质破坏。这项建议的重点是通过a5b1整合素产生的信号，它调节分解代谢介质的产生，包括细胞因子和基质金属蛋白酶(MMPs)。在最初的资助期，关键的信号蛋白被确定，必须被激活，以便纤维连接蛋白片段(Fn-f)刺激a5b1整合素导致增加的基质金属蛋白酶-13的产生。重要的是，活性氧物种(ROS)被发现是该信号通路活跃所必需的第二信使。竞争性更新的总体目标将是确定关节软骨细胞中a5b1整合素信号通路中关键的氧化还原调节信号事件的机制。一个独特的方面将是测试假设，即特定的半胱氨酸残基的氧化为磺酸是5b1整合素信号所必需的，从而导致基质金属蛋白酶-13的产生。这种重要的新近发现的细胞信号调节机制在软骨细胞中还没有报道，也没有在整合素信号通路中阐明。1)确定关节软骨细胞a5b1整合素刺激后PYK2激活的氧化还原敏感机制；2)确定pYK2下游关键的氧化还原敏感信号蛋白，这些蛋白是a5b1介导的基质金属蛋白酶-13表达所必需的；3)确定细胞因子信号转导抑制因子3(SoCS-3)在软骨细胞a5b1整合素信号转导中的作用。与公共健康相关：这些研究的结果将提供所需的新的和重要的信息，以了解控制软骨细胞(软骨细胞)过程的基本分子机制，这些过程负责产生破坏性酶，已发现这些酶会导致关节炎患者软骨组织的退化和丧失。这项工作的成功完成将为抑制关节炎的软骨破坏和预防或减缓关节炎的发展提供新的靶点。

DESCRIPTION (provided by applicant): The long-term goal of this project is to determine the mechanisms by which signals generated through integrin receptors regulate chondrocyte function. The general overall hypothesis for these studies is that changes in the cartilage extracellular matrix (ECM), including production of ECM protein fragments, are recognized by chondrocyte integrins and initiate a cascade of events intended to remodel the ECM but which in arthritis result in further matrix destruction. The focus of this proposal is on signals generated through the a5b1 integrin which regulate production of catabolic mediators including cytokines and matrix metalloproteinases (MMPs). During the initial funding period, key signaling proteins were defined that must be activated in order for fibronectin fragment (FN-f) stimulation of the a5b1 integrin to result in increased MMP-13 production. Importantly, reactive oxygen species (ROS) were found to be necessary secondary messengers for this signaling pathway to be active. The overall goal of the competitive renewal will be to determine the mechanism of key redox regulated signaling events in the a5b1 integrin signaling pathway in articular chondrocytes. A unique aspect will be testing of the hypothesis that oxidation of specific cysteine residues to sulfenic acid is necessary for a5b1 integrin signaling that results in MMP-13 production. This important and recently discovered mechanism for regulation of cell signaling has not been reported in chondrocytes or elucidated in integrin signaling pathways. The following specific aims will be pursued: 1) Determine the redox sensitive mechanism of PYK2 activation after a5b1 integrin stimulation in articular chondrocytes; 2) Determine the key redox sensitive signaling proteins downstream from PYK2 which are required for a5b1-mediated MMP-13 expression; and 3) Determine the role of the suppressor of cytokine signaling 3 (SOCS-3) in chondrocyte a5b1 integrin signaling. Public health relevance: The results from these studies will provide new and significant information needed to understand the basic molecular mechanisms which control processes in cartilage cells (chondrocytes) that are responsible for production of destructive enzymes that have been found to cause degradation and loss of cartilage tissue in people with arthritis. The successful completion of this work should provide novel targets for inhibiting cartilage destruction in arthritis and prevent or slow the development of arthritis.