Collagen transcription and lung fibrosis

某些肺损伤会导致结缔组织含量的大幅增加，尤其是胶原蛋白，从而导致纤维化。在损伤过程中，细胞暴露在干扰素-γ(干扰素-γ)和转化生长因子-β(转化生长因子-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，关于该介体对胶原蛋白的抑制作用却知之甚少。该项目致力于建立干扰素-γ抑制胶原转录的机制。我们最近描述了胶原转录起始点的X-box(RFX)结合位点的调节因子。RFX1抑制胶原转录。RFX1与c-Abl、RFX1和RNA聚合酶II(CTD)的羧基结构域相互作用，并激活c-Abl，c-Ab1是一种可以自身磷酸化的非受体酪氨酸激酶。C-Abl与RFX1在胶原转录起始点相互作用。这一提议决定了c-Abl是否参与了导致胶原合成减少的信号转导途径。当去除RFX1时，RFX5在胶原转录起始点形成一个复合体。干扰素-γ诱导第二类转录激活因子(CIITA)与RFX5相互作用，与另外两种激活主要组织相容性第二类蛋白(MHC-II)的蛋白形成复合体。由于干扰素-γ抑制胶原合成，我们推测在干扰素-γ治疗过程中，RFX蛋白介导了胶原转录抑制。我们的总体假设是，通过起始位置的RFX蛋白家族成员与其他与近端启动子结合的蛋白质协同作用，在胶原启动子上发生干扰素-γ抑制。其具体目的是：1)确定干扰素-γ治疗前后RFX家族的功能及其相互作用。2)研究c-Abl与RFX蛋白在胶原转录起始点的功能相互作用。3)检测c-Abl和RFX在不同处理条件下肺成纤维细胞和人肺组织中的定位和活性。4)利用具有胶原启动子-CAT结构的转基因动物或c-Abl或RFX5复合体缺乏的动物，研究胶原在纤维化和治疗过程中的转录调控。

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.