Translational Control in IPF

描述（由申请人提供）：纤维增生性疾病是常见的，进行性和难治性的可用治疗。来源于纤维增生性病变的成纤维细胞在生长和生存信号方面表现出无法解释的自主性。在本次修订的提案中，我们建议研究特发性肺纤维化（IPF）患者的肺成纤维细胞，这是一种原型纤维增生性疾病，并利用我们在癌症生物学方面的最新发现作为指导，阐明自主功能的机制。在人类乳腺癌的研究中，我们发现自主性是由帽依赖的翻译起始机制（称为eIF4F）的解除管制所赋予的。在正常细胞中，eIF4F接收来自基质和生长因子受体及其下游中间体的信号，并将这些输入协调成生理生长反应。在癌细胞中，eIF4F用于整合和放大来自大量生长相关基因的多种生长和生存信号，以赋予自主性。在这里，我们展示了初步数据，表明eIF4F的异常激活是IPF成纤维细胞的一个特性；在缺乏生长因子的情况下，激活成纤维细胞中的eIF4F刺激细胞周期进入；并且通过基因工程缺乏eIF4F负调节因子的小鼠有夸大的纤维化反应。因此，我们假设控制细胞周期运输的转录物的不受调节的翻译控制位于纤维化的因果途径上；并提出2个具体目标来验证这一假设：具体目标1：将IPF成纤维细胞中显示翻译效率协调变化的转录本分类为基于共享的化学和生物学特性的离散组。化学：包含已知或候选RNA调控元件的核苷酸序列。B.生物学：指定的功能。特异性目标2：关注编码细胞周期调节因子的转录本，确定破坏调节元件功能是否会减弱IPF成纤维细胞的增殖自主性。A.已知的监管要素。B.新发现的调控因素。如果成功，我们的研究将精确地确定基因表达的翻译步骤中的紊乱，这些紊乱赋予IPF成纤维细胞增殖自主性，从而揭示肺和其他器官抗纤维化治疗的新分子靶点。公共卫生相关性。许多人类疾病的特点是疤痕组织积累，导致器官功能障碍和死亡。疤痕，也称为纤维化，可以影响许多不同的器官，包括肺、肝、肾、心脏、脉管系统和皮肤；而且通常很难治疗。在这里，我们建议研究产生疤痕组织的细胞，成纤维细胞，一种致命的肺瘢痕形式，在美国折磨着超过35,000人，称为特发性肺纤维化（IPF）。我们的初步实验指出了产生蛋白质的细胞机制的异常激活，其模式与癌症相似。我们在这项研究中的目标是了解成纤维细胞的生物学是如何通过蛋白质合成机制的异常以导致肺纤维化的方式被重定向的。通过揭示抗纤维化治疗的新分子靶点，这一信息有可能为所有疤痕性疾病带来新的治疗方法。

DESCRIPTION (provided by applicant): Fibroproliferative disorders are common, progressive and refractory to available therapy. Fibroblasts derived from fibroproliferative lesions manifest an unexplained autonomy for growth and survival signals. In this revised proposal, we propose to study lung fibroblasts from patients with Idiopathic Pulmonary Fibrosis (IPF), a prototype fibroproliferative disease, and elucidate the mechanism of autonomous function using our recent discoveries in cancer biology as a guide. In studies of human breast carcinoma, we discovered that autonomy is conferred by deregulation of the cap-dependent translation initiation machinery, designated eIF4F. In normal cells, eIF4F receives signals from matrix and growth factor receptors and their downstream intermediates, and orchestrates these inputs into a physiological growth response. In cancer cells, eIF4F serves to integrate and amplify diverse growth and survival signals emanating from a plethora of growth-related genes to confer autonomy. Here we show preliminary data indicating that aberrant activation of eIF4F is a property of IPF fibroblasts; that activating eIF4F in fibroblasts stimulates cell cycle entry in the absence of growth factors; and that mice genetically engineered to lack negative regulators of eIF4F have an exaggerated fibrotic response. We therefore hypothesize that deregulated translational control of transcripts governing cell cycle transit lies on the causal pathway to fibrosis; and propose 2 specific aims to test this hypothesis: Specific Aim 1: Classify transcripts in IPF fibroblasts that display coordinate changes in translational efficiency into discrete groups based on shared chemical and biological characteristics. A. Chemical: Nucleotide sequences that comprise known or candidate RNA regulatory elements. B. Biological: Assigned function. Specific Aim 2: Focusing on transcripts encoding cell cycle regulators, determine whether disrupting regulatory element function attenuates IPF fibroblast proliferative autonomy. A. Known regulatory elements. B. Newly discovered regulatory elements. If successful, our studies will precisely identify derangements in the translational step of gene expression that confer IPF fibroblasts with proliferative autonomy, thus revealing new classes of molecular targets for antifibrotic therapy in the lung and other organs. PUBLIC HEALTH RELEVANCE. Many human diseases are characterized by scar tissue accumulation that leads to organ dysfunction and death. Scarring, also called fibrosis, can affect many different organs including the lung, liver, kidney, heart, vasculature and skin; and is often very difficult to treat. Here we propose to study the cell producing scar tissue, the fibroblast, in a deadly form of lung scarring that afflicts more than 35,000 people in the US, termed idiopathic pulmonary fibrosis (IPF). Our pilot experiments point to abnormal activation of the cellular machinery that produces protein, in a pattern similar to that seen in cancer. Our goal in this study is to understand how the biology of fibroblasts can be redirected by abnormalities in the protein synthesis machinery in a manner that leads to lung fibrosis. This information has the potential to lead to new treatments for all scarring diseases by revealing new molecular targets for antifibrotic therapy.