Collagen transcription and lung fibrosis

某些肺损伤引起结缔组织含量，特别是胶原蛋白含量的大量增加，导致纤维化。在损伤过程中，细胞暴露于干扰素- γ (ifn - γ)和转化生长因子- β (tgf - β)等分子中，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，对胶原蛋白的抑制作用知之甚少。本项目的重点是建立胶原转录被IFN- γ抑制的机制。我们最近描述了一个在胶原转录起始位点的X-box （RFX）结合位点的调节因子。RFX1抑制胶原转录。RFX1与c-Abl相互作用并激活c-Abl， c-Abl是一种非受体酪氨酸激酶，可以使自身磷酸化，RFX1和RNA聚合酶II （CTD）的羧基结构域。C-Abl在胶原转录起始位点与RFX1相互作用。该建议确定c-Abl是否参与导致胶原合成减少的信号转导途径。当RFX1被移除时，RFX5在胶原转录起始位点形成复合物。ifn - γ诱导II类转录激活因子（CIITA）与RFX5相互作用，与另外两种激活主要组织相容性II类蛋白（MHC-II）的蛋白形成复合物。由于ifn - γ抑制胶原合成，我们假设RFX蛋白在ifn - γ治疗过程中介导胶原转录抑制。我们的总体假设是，ifn - γ抑制发生在胶原启动子上，是通过RFX蛋白家族成员在起始位点与其他与近端启动子结合的蛋白的合作相互作用。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)研究c-Abl与RFX蛋白在胶原转录起始位点的功能相互作用。3)检测c-Abl和RFX在不同处理下和人肺组织样本中肺成纤维细胞的定位和激酶活性。4)利用胶原-启动子- cat构建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过程中胶原转录调控。

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.