Novel Pathways in TGF BETA Signaling

 描述（由申请人提供）：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传导调节因子（CFTR）（一种cAMP激活的氯离子通道）的基因突变引起。CF患者会出现慢性肺部感染和炎症，部分由白细胞介素（IL）-17A介导，导致支气管扩张，最终导致呼吸衰竭和死亡。CF与炎症起主要作用的许多其他形式的肺部疾病有共同的特征。90%的CF患者携带至少一个拷贝的CF 508等位基因。目前对CF肺病的治疗仅在具有CF 3F 508突变的CF患者中略微有效。一个关键的限制是大多数CF患者产生高水平的转化生长因子（TGF）-β1。我们已发表的工作表明，TGF-β1抑制HBE细胞中的TGF-508-CFTR转录，作用于治疗剂VX-809的上游，从而阻断其疗效。高TGF-β1水平也会引发CF患者的炎症。因此，TGF-β1信号传导是除了促进炎症之外限制VX-809在CF中的功效的主要内源性途径。我们的初步数据证实，VX-809既不逆转TGF-β1对CFTR转录的抑制，也不逆转IL-17 A诱导的炎性细胞因子分泌。TGF-β1具有多种稳态作用，包括伤口愈合和T细胞分化。目前尚不清楚如何精确靶向TGF-β1的致病作用而不损害稳态功能。针对TGF-β1途径中细胞类型特异性和疾病相关激活剂可以作为一种新型治疗策略，选择性消除CF中TGF-β1的致病性后遗症。我们已经证明Dab 2（disabled-2）可能在人支气管上皮（HBE）细胞中发挥这种作用，其作用于TGF-β1受体下游，并指导TGF-β1途径中的关键介质Smad 3的核运输。我们的中心假设是TGF-β1稳定了Dab 2-Smad 3相互作用以增加Smad 3的核递送，从而导致HBE细胞中IF 508-CFTR转录和炎症的抑制。Dab 2有利于Smad 3信号传导，阻断VX-809对CFTR 508-CFTR蛋白的拯救，促进促炎性串扰，并抑制结果。因此，Dab 2-Smad 3界面代表了CF和炎症由TGF-β1介导的其他形式的肺部疾病的新治疗靶标。在目的1中，我们将检验Dab 2和Smad 3介导TGF-β1在HBE细胞中的致病作用的假设。目的2验证Dab 2特异性地指导HBE细胞中激活的Smad 3核转位的假设。在目的3中，我们将检验这样的假设，即在HBE细胞中TGF-β1的致病作用需要Dab 2与Smad 3相互作用。我们预计，我们的研究将导致新的治疗精确靶向致病性TGF-β1活性，以保护 气道完整性，并提高矫正器的功效以恢复CF患者中的CFNF 508-CFTR功能。我们的研究也将使许多其他常见的非CF肺部疾病患者受益。

 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.