Novel Pathways in TGF BETA Signaling

 描述(申请人提供)：囊性纤维化(CF)是高加索人中最常见的隐性疾病，由编码囊性纤维化跨膜电导调节因子(CFTR)的基因突变引起，CFTR是一种cAMP激活的氯离子通道。Cf患者出现慢性肺部感染和炎症，部分原因是白介素17A导致支气管扩张，最终导致呼吸衰竭和死亡。Cf与许多其他形式的肺部疾病有相同的特征，在这些疾病中，炎症起着主要作用。90%的CF患者至少携带一份∆F508等位基因。目前治疗慢性阻塞性肺疾病的方法对∆F508突变的慢性阻塞性肺疾病患者仅略微有效。我们已发表的研究表明，转化生长因子-β1抑制HBE细胞中∆F508-cftr的转录，作用于治疗剂VX-809的上游，从而阻断其疗效。高水平的转化生长因子-β-1也促进了CF患者的炎症反应。因此，转化生长因子-β1信号通路是限制VX-809促炎症作用的主要内源性途径。我们的初步数据证实，VX-809既不能逆转转化生长因子-β1对cftr转录的抑制，也不能逆转IL-17A诱导的炎性细胞因子的分泌。转化生长因子-β-1具有多种动态平衡作用，包括自愈和T细胞分化。目前尚不清楚如何在不损害体内平衡功能的情况下准确靶向转化生长因子-β-1的致病作用。靶向转化生长因子-β-1途径中的细胞类型特异性和疾病相关的激活物可作为选择性消除转化生长因子-β-1在CF中的致病后遗症的新的治疗策略。我们发现DAB2(失活的-2)可能作用于转化生长因子-β-1受体的下游，并指导转化生长因子-β-1途径的关键介质Smad3在人支气管上皮细胞中的核转运。我们的中心假设是，转化生长因子-β1稳定了∆-Smad3的相互作用，增加了Smad3的核递送，从而抑制了HBE细胞中Smad3的转录和炎症。DAB2促进Smad3信号转导，阻断VX-809对∆F508-cftr蛋白的挽救，促进促炎反应，恶化预后。在目标1中，我们将验证DAB2和Smad3介导转化生长因子-β1在HBE细胞中的致病作用的假设。在Aim 2中，测试DAB2指导激活的Smad3在HBE细胞中特异性核转位的假设。在目标3中，我们将检验这一假设，即-β1在HBE细胞中的致病作用需要DAB2Smad3相互作用。我们预计，我们的研究将导致精确针对致病转化生长因子-β1活性的新疗法，以保存 以提高矫正器的疗效，恢复慢性阻塞性肺疾病患者的∆F508-cftr功能。我们的研究也将使许多其他常见的非循环肺疾病患者受益。

 DESCRIPTION (provided by applicant): Cystic Fibrosis (CF), the most common recessive disease among Caucasians, is caused by mutations in the gene encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), a cAMP-activated chloride ion channel. CF patients develop chronic lung infection and inflammation, which can be mediated in part by interleukin (IL)-17A leading to bronchiectasis, and ultimately respiratory failure and death. CF shares features with many other forms of lung disease where inflammation plays a major role. Ninety percent of CF patients carry at least one copy of the ∆F508 allele. Current treatment for CF lung disease is only marginally effective in CF patients with the ∆F508 mutation. A key limitation is that most CF patients produce high levels of Transforming Growth Factor (TGF)-β1. Our published work has shown that TGF-β1 represses ∆F508-CFTR transcription in HBE cells, acting upstream of the therapeutic agent VX-809 and thus blocks its efficacy. High TGF-β1 levels also prime CF patients for inflammation. Thus, TGF-β1 signaling is a major endogenous pathway limiting the efficacy of VX-809 in CF in addition to promoting inflammation. Our preliminary data confirm that VX-809 reverses neither the TGF-β1 inhibition of CFTR transcription nor the IL-17A induced secretion of inflammatory cytokines. TGF-β1 has many homeostatic effects, including would healing and T-cell differentiation. Currently it is unknown how to precisely target the pathogenic effects of TGF-β1 without compromising the homeostatic function. Targeting the cell-type specific and disease-relevant activators in the TGF-β1 pathway could serve as a novel therapeutic strategy to selectively eliminate the pathogenic sequels of TGF-β1 in CF. We have shown that Dab2 (disabled-2) may play such role acting downstream of TGF-β1 receptors, and directing nuclear trafficking of a key mediator in TGF-β1 pathway, Smad3 in human bronchial epithelial (HBE) cells. Our central hypothesis is that TGF-β1 stabilizes the Dab2-Smad3 interaction to increase nuclear delivery of Smad3 leading to repression of ∆F508-CFTR transcription and inflammation in HBE cells. Dab2 favors Smad3 signaling, blocks ∆F508-CFTR protein rescue by VX-809, feeds the pro-inflammatory cross-talk, and worsens outcomes. The Dab2-Smad3 interface thus represents a novel therapeutic target for CF and for other forms of lung disease where inflammation is mediated by TGF-β1. In aim 1, we will test the hypothesis that Dab2 and Smad3 mediate the pathogenic effects of TGF-β1 in HBE cells. In aim 2 test the hypothesis that Dab2 directs nuclear translocation of activated Smad3 specifically in HBE cells. In aim 3 we will test the hypothesis that a Dab2Smad3 interaction is required for the pathogenic effects of TGF-β1 in HBE cells. We anticipate that our studies will lead to novel therapy precisely targeting the pathogenic TGF-β1 activity, to preserve airway integrity, and to promote efficacy of correctors to restore the ∆F508-CFTR function in CF patients. Our studies will also benefit many other patients with common non-CF lung disease.