Raft/Caveolar Mechanisms in Pulmonary Hypertension

描述（由申请人提供）： 这个翻译研究的建议，旨在应用最近的新见解细胞信号转导的质膜水平（小窝/筏信号转导假说和白细胞介素-6-raft-STAT 3信号转导模型）的发病机制的理解PH.小窝蛋白-1含有洗涤剂抗性质膜筏现在被认为是专门的信号细胞器，包括细胞因子信号。现在有越来越多的证据表明细胞因子在肺部疾病的发病机制中的作用。例如，在原发性肺动脉高压（PH）和与自身免疫性疾病和AIDS相关的PH中观察到IL-6的血清水平升高。在大鼠模型中，单次注射植物生物碱野百合碱（MCI）在48小时内导致内皮细胞损伤、膜渗漏、IL-6 mRNA和生物活性上调，但肺中小窝蛋白-1显著下调，随后在10-14天后发展为PH。 拟定研究的重点是双管齐下：（a）评价MCT导致的肺内皮细胞筏/小窝破坏是PH发病机制中的起始事件的假设（特定目的I），以及（B）研究肺特异性细胞中IL-6诱导的STAT 3信号传导中膜筏和新发现的含胞质小窝蛋白的Palade复合物的功能（特定目的II和III）。目的我将包括调查的时间过程，组织学位置，和细胞和分子机制下调小窝蛋白和基因表达，和完整的小窝/筏功能在肺血管和parenehymal组织的MCT处理的大鼠。目的II包括STAT 3与小窝蛋白-1的关联机制以及STAT 3在肺内皮细胞、肺泡II型样上皮细胞和肺成纤维细胞质膜筏中的活化机制的分子研究。目的III包括研究含STAT 3的胞质Palade复合物的蛋白组分及其在将信号分子从质膜筏转运到细胞内部的功能。 从该项目中获得的机制见解可能会提出肺动脉高压管理的新治疗方法。此外，所提出的研究具有特别广泛的意义，因为对参与raft-STAT信号传导的分子机制的深入了解可能适用于在可能所有细胞类型中由精氨酸介导的STAT转录因子的活化，以及定位于筏微结构域中的其他信号传导途径（eNOS和血管紧张素II信号传导）。

DESCRIPTION (provided by applicant): This translational research proposal seeks to apply recent novel insights into the mechanisms of cell signaling at the level of the plasma membrane (the caveola/raft signaling hypothesis and the interleukin-6-raft-STAT3 signaling model) to an understanding of the pathogenesis of PH. Caveolin-1-containing detergent-resistant plasma membrane rafts are now recognized as specialized signaling organelles, including cytokine signaling. There is now growing evidence for a role of cytokines in the pathogenesis of lung diseases. As examples, elevated serum levels of IL-6 have been observed in primary pulmonary hypertension (PH) and in PH associated with autoimmune diseases and AIDS. In a rat model, a single injection of the plant alkaloid monocrotaline (MCI) results within 48 hrs in endothelial cell damage, membrane leakage, upregulation of IL-6 mRNA and bioactivity but a marked downregulation of caveolin-1 in the lung, followed by development of PH 10-14 days later. The focus of the proposed studies is two-pronged: (a) to evaluate the hypothesis that pulmonary endothelial-cell raft/caveolar disruption by MCT is an initiating event in the pathogenesis of PH (Specific Aim I), and (b) to investigate the function of membrane rafts and of the newly discovered cytosolic caveolin-containing Palade complexes in IL-6-induced STAT3 signaling in lung-specific cells (Specific Aims II and III). Aim I will include investigations of the time-course, histologic location, and cellular and molecular mechanisms for the downregulation of caveolin proteins and gene expression, and of the integrity of caveolar/raft function in pulmonary vascular and parenehymal tissues of MCT-treated rats. Aim II includes molecular studies of the mechanisms of association of STAT3 with caveolin-1 and of STAT3 activation in plasma membrane rafts in pulmonary endothelial cells, alveolar type II-like epithelial cells and lung fibroblasts. Aim Ill includes studies of the protein components of STAT3-containing cytosolic Palade complexes and their function in ferrying signaling molecules from the plasma membrane rafts to the cell interior. Mechanistic insights derived from this project are likely to suggest novel therapeutic approaches in the management of pulmonary hypertension. Moreover, the proposed studies are of particularly broad significance in that insights into the molecular mechanisms involved in raft-STAT signaling are likely to be applicable to cytokine-mediated activation of STAT transcription factors in perhaps all cell types, as well as to other signaling pathways localized in raft microdomains (eNOS and angiotensin II signaling).