Mutant Surfactant - Induced TGF-beta Secretion in Lung Fibrosis

描述(申请人提供)：编码表面活性物质蛋白A2(SP-A2)的基因突变会导致家族性特发性肺纤维化(IPF)和肺癌，这两种致命疾病的治疗选择有限。突变表面活性蛋白的分子机制尚不清楚，是影响儿童和成人的一系列肺部疾病的基础。我们最近发现，某些突变型表面活性物质蛋白在肺上皮细胞中的表达和分泌增加了潜在的转化生长因子，这是一种强大的促纤维化和促癌细胞因子。需要检验的具体假设是，肺泡上皮细胞表达突变的表面活性物质蛋白，通过自分泌和旁分泌作用导致肺纤维化，其分泌是通过内质网应激依赖和内质网应激非依赖性途径诱导的。我们建议的工作的基本原理是，它将提供对突变表面活性蛋白在导致进行性肺纤维化中的功能获得效应的更好的理解。第一个目标将集中在体外研究这一机制，通过确定：哪些不同的表面活性蛋白具有诱导潜在的转化生长因子-β分泌增加的功能获得效应，以及介导这一机制的内质网应激信号的相对贡献是什么？潜在途径的分子机制将使用蛋白质组学和转录组学方法以及化学抑制剂相结合的方法来探索。第二个目标将定义II型肺泡上皮的损伤或重新编程 突变型表面活性蛋白的急性或慢性表达以及影响转化生长因子-β信号转导的细胞背景的各种途径的参与所引起的细胞。在第三次也是最后一次瞄准时， 我们将使用一种新的转基因小鼠模型来阐明突变型SP-A2蛋白介导的疾病的体内分子机制。我们将专门探讨在博莱霉素诱导的肺纤维化中，转化生长因子-β信号通路和端粒酶通路的遗传作用。虽然转化生长因子下游的信号通路被很好地描述，但导致其表达和分泌的刺激事件却没有被很好地描述。这些目标的成功完成将阐明突变表面活性物质诱导潜在的转化生长因子-β分泌的这一新途径。这项工作将深入了解肺纤维化中蛋白质错误折叠、内质网应激、EMT、细胞分化和增殖的途径，并将有助于确定药物开发的独特靶点。

DESCRIPTION (provided by applicant): Mutations in the gene encoding surfactant protein A2 (SP-A2) cause familial idiopathic pulmonary fibrosis (IPF) and lung cancer, both lethal diseases with limited treatment options. The molecular mechanism of mutant surfactant proteins are not well understood and underlie a spectrum of lung diseases affecting children and adults. We have recently discovered that expression of certain mutant surfactant proteins in lung epithelial cells leads to increased expression and secretion of latent TGF-ß, a potent pro-fibrotic and pro-oncogenic cytokine. The specific hypothesis to be tested is that expression of mutant surfactant proteins in alveolar epithelial cells leads to pulmonary fibrosis through the autocrine and paracrine effects of TGF-ß, whose secretion is induced through ER stress-dependent and ER stress-independent pathways. Our rationale for the proposed work is that it will provide enhanced understanding of the gain-of-function effects of mutant surfactant proteins in causing progressive pulmonary fibrosis. The first aim will focus on studying this mechanism in vitro by determining: Which variant surfactant proteins have a gain-of-function effect of inducing increased latent TGF-ß secretion and what is the relative contribution of ER stress signaling that mediates this mechanism? The molecular mechanism of the underlying pathways will be probed using a combination of proteomic and transcriptomic approaches as well as chemical inhibitors. The second aim will define the injury or "reprogramming" of type II alveolar epithelial cells caused by acute or chronic expression of mutant surfactant proteins and the involvement of various pathways that affect the cellular context of TGF-ß signaling. In the third and last aim, we will elucidate the in vivo molecular mechanism of mutant SP-A2 protein-mediated disease using a novel transgenic mouse model. We will specifically explore the genetic contributions of the TGF-ß signaling and telomerase pathways in contributing to bleomycin-induced lung fibrosis. While the signaling pathways downstream of TGF-ß are well characterized, the inciting events that lead to its expression and secretion are not. Successful completion of these aims will elucidate this novel pathway of mutant surfactant induced latent TGF-ß secretion. This work will generate insight into the pathways linking protein misfolding, ER stress, EMT, cellular differentiation and proliferation in lung fibrosis and will assist in the identification of unique targets for drug development.