Collagen Transcription and Lung Fibrosis

描述(申请人提供)：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，从而导致肺纤维化。在损伤、炎症和修复过程中，细胞暴露在由炎症细胞释放的干扰素-γ(干扰素-γ)和转化生长因子-β(转化生长因子-β)等分子中，调节胶原的产生。I型胶原的转录在损伤的炎症反应后被激活，以修复损伤。这个过程之后是转录的抑制。如果没有转录抑制，进行性纤维化会导致肺组织。我们假设，转录的变化需要多个蛋白质协同作用来改变转录和染色质结构，以响应细胞因子信号。在上一次资助期间，我们重点研究了干扰素-γ抑制胶原转录的机制。干扰素-γ增加X-box 5(RFX5)复合体调节因子的表达，该复合体定位于细胞核，与胶原基因转录起始点相互作用，抑制胶原合成。第二类反式激活因子(CIITA)在干扰素-γ治疗早期显著增加，并与RFX5复合体相互作用。干扰素诱导的CIITA蛋白负责主要组织相容性复合体(MHC)的激活和胶原基因表达的抑制。由于炎症反应增加，干扰素-γ治疗间质性肺纤维化的临床试验一直未获成功。我们推测，RFX5/CIITA蛋白可能通过单独的CIITA反式激活和抑制结构域负责激活炎症反应，同时抑制胶原。我们有令人信服的证据表明，许多蛋白质，包括辅助抑制物，在抑制过程中结合到胶原蛋白起始点。转化生长因子-β等药物的激活可能会将不同的蛋白质招募到胶原基因中。其具体目的是：1)确定在干扰素-γ治疗过程中与胶原起始部位相互作用的蛋白质。2)检测结合在启动子上游的激活蛋白与有无转化生长因子-β的RFX蛋白家族的功能相互作用。3)检测具有和不具有胶原启动子-CAT结构的CIITA突变和/或缺失动物的博莱霉素诱导的纤维化，以研究纤维化过程中的炎症和胶原转录调节。

DESCRIPTION (provided by applicant): Certain lung injuries induce large increases in connective tissue content, particularly collagen, resulting in pulmonary fibrosis. During injury, inflammation, and repair, cells are exposed to molecules such as interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) that are released by inflammatory cells and regulate production of collagen. Collagen type I transcription is activated after inflammatory response to injury in order to repair damage. This process is followed by repression of transcription. Without transcriptional repression, progressive fibrosis results in the lung. We hypothesize that changes in transcription require multiple proteins interacting cooperatively to alter transcription and chromatin structure in response to cytokine signals. During the last funding period, we focused on the mechanism of IFN-gamma induced repression of collagen transcription. IFN-gamma increases expression of regulatory factor for X-box 5 (RFX5) complex proteins which localizes in the nucleus, interacts with the collagen gene transcriptional start site and represses collagen synthesis. Class II transactivator (CIITA) dramatically increases early during IFN-gamma treatment and interacts with RFX5 complex. IFN-gamma-induced CIITA protein is responsible for both activation of major histocompatibility complex (MHC) and repression of collagen gene expression. Clinical trials for interstitial pulmonary fibrosis with IFN-gamma have been unsuccessful due to increased inflammatory response. We hypothesize that RFX5/CIITA proteins may be responsible for activating inflammatory responses while repressing collagen through separate CIITA transactivation and repression domains. We have compelling evidence that many proteins including co-repressors bind to the collagen start site during repression. Activation by agents such as TGF-beta may recruit different proteins to the collagen gene. The specific aims are to; 1) Determine the proteins interacting with the collagen start site during IFN-gamma treatment. 2) Examine the functional interactions of activation proteins binding upstream in the promoter with RFX family of proteins with and without TGF-beta. 3) Examine bleomycin induced fibrosis in animals with CIITA mutations and/or deficiencies with and without collagen-promoter-CAT constructs to investigate inflammation and collagen transcriptional regulation during fibrosis.