Collagen transcription and lung fibrosis

某些肺损伤会导致结缔组织含量（尤其是胶原蛋白）大量增加，从而导致纤维化。在损伤期间，细胞暴露于干扰素-γ (IFN-γ) 和转化生长因子-β (TGF-β) 等分子，调节基质成分的产生。间质性肺纤维化（IPF）的临床试验正在进行中。然而，人们对这种介质对胶原蛋白的抑制知之甚少。该项目的重点是建立 IFN-γ 抑制胶原蛋白转录的机制。我们最近描述了胶原蛋白转录起始位点 X-box (RFX) 结合位点的调节因子。 RFX1 抑制胶原转录。 RFX1 与 c-Abl（一种可磷酸化自身的非受体酪氨酸激酶）、RFX1 和 RNA 聚合酶 II (CTD) 的羧基结构域相互作用并激活 c-Abl。 C-Abl 在胶原蛋白转录起始位点与 RFX1 相互作用。该提议确定了 c-Abl 是否参与导致胶原蛋白合成减少的信号转导途径。当 RFX1 被去除时，RFX5 在胶原蛋白转录起始位点形成复合物。 IFN-γ 诱导 II 类转录激活因子 (CIITA)，它与 ​​RFX5 相互作用，与其他两种蛋白形成复合物，激活主要组织相容性 II 类蛋白 (MHC-II)。由于 IFN-γ 抑制胶原蛋白合成，我们假设 RFX 蛋白在 IFN-γ 治疗期间介导胶原蛋白转录抑制。我们的总体假设是，通过起始位点的 RFX 蛋白家族成员与结合到近端启动子的其他蛋白的协同相互作用，IFN-γ 抑制发生在胶原蛋白启动子上。具体目标是： 1)确定IFN-γ治疗前后RFX家族的功能和相互作用。 2) 检查 c-Abl 与 RFX 蛋白在胶原蛋白转录起始位点的功能相互作用。 3) 检查不同处理下的肺成纤维细胞和人肺组织样本中c-Abl和RFX的定位和激酶活性。 4) 使用具有胶原启动子-CAT 构建体的转基因动物或缺乏 c-Abl 或 RFX5 复合物的动物来研究纤维化和治疗期间的胶原转录调节。

Certain lung injuries induce large increases in connective tissue content, particularly collagen, resulting in fibrosis. During injury, cells are exposed to molecules such as interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta), regulating production of matrix components. Clinical trials for interstitial pulmonary fibrosis (IPF) are ongoing. However, very little is understood concerning collagen repression by this mediator. This project focuses on establishing the mechanisms by which collagen transcription is repressed by IFN- gamma. We have recently described a regulatory factor for X-box (RFX) binding site at the collagen transcription start site. RFX1 represses collagen transcription. RFX1 interacts with and activates c-Abl, a non- receptor tyrosine kinase that can phosphorylate itself, RFX1 and the carboxyl domain of RNA polymerase II (CTD). C-Abl interacts with RFX1 at the collagen transcription start site. This proposal determines whether c-Abl participates in signal transduction pathways leading to decreased collagen synthesis. RFX5 forms a complex at the collagen transcription start site when RFX1 is removed. IFN-gamma induces class II transcription activator (CIITA) which interacts with RFX5 forming a complex with two other proteins that activate major histocompatibility class II proteins (MHC-II). Since IFN-gamma represses collagen synthesis, we hypothesize that RFX proteins mediate collagen transcription repression during IFN-gamma treatment. Our overall hypothesis is that IFN-gamma repression occurs on the collagen promoter by cooperative interactions of RFX protein family members at the start site with other proteins binding to the proximal promoter. The specific aims are to; 1) Determine the function and interactions of RFX family before and after IFN-gamma treatment. 2) Examine the functional interactions of c-Abl with RFX proteins at the collagen transcription start site. 3) Examine the localization and kinase activity of c-Abl and RFX in lung fibroblasts under different treatments and in samples of human lung tissue. 4) Use transgenic animals with collagen-promoter-CAT constructs or animals deficient in c-Abl or RFX5 complex to investigate collagen transcriptional regulation during fibrosis and treatment.