Defining the role of Factor Inhibiting HIF (FIH) as a key regulator of extracellular matrix homeostasis

细胞外基质（ECM）是体内细胞和组织功能最重要的调节因子之一。ECM的动态重塑对于发育、创伤愈合和正常器官的稳态是必不可少的。当ECM重塑变得过度或不受控制时，会出现危及生命的病理状况，如器官纤维化。ECM被定义为在所有实体组织中围绕细胞的蛋白质和糖的多样性集合。虽然ECM在历史上被认为主要是履行结构和生物力学的作用，ECM提供负责控制个人和集体的细胞行为的背景信息的能力，近年来已经越来越多地认识到。ECM的生物力学性质受到基质组分的特定组成和浓度以及翻译后修饰（如糖基化、转谷氨酰胺化和交联）的严格控制。我们最近发现，纤维化的肺组织比正常的硬，由于增加的“骨”型胶原交联，这促进了纤维化的进展。通过人体体外和组织分析，我们确定了HIF途径活化驱动这种病理性“骨型”交联，并且这是通过HIF信号传导的氧非依赖性活化-称为假缺氧-通过HIF抑制因子（FIH）活性的丧失来确定的。此外，我们确定了高HIF基因标记评分强烈预测肺纤维化的死亡率，而与肺生理学严重程度无关。因此，我们的假设是，FIH功能的丧失产生了一种假性缺氧表型，这种表型驱动了进行性纤维化。本项目的目的是使用先进的原代人类细胞和组织为基础的模型，辅以系统和定量生物学方法，以确定：（1）全球转录组概况的FIH-耗尽肺成纤维细胞;（2）生物和分子变化后，FIH耗尽肺成纤维细胞;（3）的影响，失去FIH活性ECM homeostasis。

The extracellular matrix (ECM) is one of the most important regulators of cellular and tissue function in the body. Dynamic remodeling of ECM is essential for development, wound healing and normal organ homeostasis. Life-threatening pathological conditions, such as organ fibrosis, arise when ECM remodeling becomes excessive or uncontrolled. The ECM is defined as the diverse collection of proteins and sugars that surrounds cells in all solid tissues. Although the ECM has historically been perceived as fulfilling a primarily structural and hence biomechanical role, the ability of the ECM to provide the contextual information responsible for controlling both individual and collective cellular behavior has been increasingly recognized in recent years. The biomechanical properties of the ECM are tightly controlled by the specific composition and concentration of matrix components, and also by post-translational modifications, such as glycosylation, transglutamination and cross-linking. We have recently identified that fibrotic lung tissue is stiffer than normal due to increased 'bone' type collagen cross-linking and that this promotes fibrosis progression. Through human in vitro and tissue analyses we identified that HIF pathway activation drives this pathologic 'bone type' crosslinking, and that this is determined through oxygen-independent activation of HIF signalling - termed pseudohypoxia - by loss of activity of Factor Inhibiting HIF (FIH). Furthermore, we identified that a high HIF gene signature score is strongly predictive of mortality of lung fibrosis independent of lung physiology severity. Thus, our hypothesis is that loss of function of FIH creates a pseudohypoxic phenotype that drives progressive fibrosis. The aims of this project are to use advanced primary human cell and tissue based models complemented by systems and quantitative biology approaches to determine:(1) global transcriptomic profiling of FIH-depleted lung fibroblasts;(2) biological and molecular changes following FIH depletion in lung fibroblast;(3) the impact of loss of FIH activity on ECM homeostasis.This project will define the role of FIH as a key regulator of extracellular matrix remodelling.