Characterization of an inhibitory protein complex for cystic fibrosis therapy

描述（由申请方提供）：囊性纤维化（CF）是一种致死性常染色体隐性遗传疾病，由突变导致CF跨膜传导调节因子（CFTR）Cl-通道活性丧失或功能障碍引起。临床上，慢性肺病是 是CF患者发病和死亡的主要原因。在1900多个致病突变中，c.1521_1523delCTT（F508 del）是最常见的突变，并且与严重形式的CF疾病相关。与F508 del相关的CF的理想疗法需要增加细胞表面的蛋白质量，以增强受损的通道门控特性并改善蛋白质稳定性。这一观点得到了来自患有F508 del的CF患者的临床试验的有希望的结果的支持，该结果表明使用VX-809（CFTR校正剂）和ivacaftor（CFTR增效剂）的组合方法导致研究受试者的肺功能的显著改善。在这项提议中，我们计划研究一种以前未被识别的抑制性蛋白复合物，该蛋白复合物含有被拯救的F508 del-CFTR、Na+/H+交换调节因子-2（NHERF 2）和2型溶血磷脂酸受体（LPA 2），并破坏该复合物以增加F508 del-CFTR通道功能。待测试的统一假设是：（i）拯救的F508 del-CFTR，像野生型CFTR一样，在质膜处与NHERF 2和LPA 2形成抑制性复合物;（ii）通过特异性破坏NHERF 2-LPA 2相互作用来破坏该复合物将增强F508 del-CFTR的通道功能;（iii）因为破坏NHERF 2-LPA 2相互作用的分子机制独立于VX-809或VX-770作用的分子机制，NHERF 2-LPA 2抑制剂可与VX-809和VX-770在增强F508 del-CFTR通道功能方面具有相加或协同作用。这项研究不仅将揭示一种以前未被识别的抑制F508 del-CFTR通道功能的蛋白复合物，而且还将提供一种通过消除这种抑制性信号来增强F508 del-CFTR通道功能的新方法。因为除了F508 del之外，各种其他CFTR突变也可以与NHERF 2和LPA 2形成复合物，所以我们提出的方法可能对CFTR突变具有广谱增强作用。因此，我们的研究将扩大我们对CFTR相互作用组的了解，并帮助我们更好地了解F508 del-CFTR在细胞表面的病理生物学。此外，我们的破坏方法可能为开发治疗与各种突变相关的CF的药物开辟了新的途径。

DESCRIPTION (provided by applicant): Cystic fibrosis (CF) is a lethal autosomal recessive inherited disease caused by the loss or dysfunction of the CF transmembrane conductance regulator (CFTR) Cl- channel activity resulting from mutations. Clinically, chronic lung disease is the main cause of morbidity and mortality for CF patients. Among the 1900+ disease- causing mutations, c.1521_1523delCTT (F508del) is the most common mutation and associates with a severe form of CF disease. The ideal therapy for CF associated with F508del requires an increase in the quantity of protein at the cell surface, to potentiate the impaired channel gating properties and to improve protein stability. This notion was supported by promising results from clinical trials on CF patients with F508del, which demonstrated that a combinational approach using VX-809 (a CFTR corrector) and ivacaftor (a CFTR potentiator) led to significant improvements in the lung function of the study subjects. In this proposal, we plan to study a previously unrecognized inhibitory protein complex containing the rescued F508del-CFTR, Na+/H+ exchanger regulator factor-2 (NHERF2) and type-2 lysophosphatidic acid receptor (LPA2), and to pharmacologically disrupt this complex to increase F508del-CFTR channel function. The unifying hypothesis to be tested is that (i) the rescued F508del-CFTR, like wild type CFTR, forms an inhibitory complex with NHERF2 and LPA2 at the plasma membrane; (ii) disruption of this complex by specifically disrupting the NHERF2-LPA2 interaction will potentiate the channel function of F508del-CFTR; (iii) because the molecular mechanism underlying the disruption of NHERF2-LPA2 interaction is independent of that underlying the effect of VX-809 or VX-770, the NHERF2-LPA2 inhibitors can have additive or synergistic effects with VX-809 and VX-770 on augmentation of F508del-CFTR channel function. The proposed study will not only unveil a previously unrecognized protein complex that inhibits F508del-CFTR channel function, but will also provide a novel approach to augmenting F508del-CFTR channel function by abrogating this inhibitory signaling. Because, in addition to F508del, a variety of other CFTR mutations can also form complexes with NHERF2 and LPA2, the approach we propose could have a broad spectrum potentiating effect on CFTR mutations. Therefore, our study will expand our knowledge of the CFTR interactome and help us better understand the pathobiology of F508del-CFTR at the cell surface. Furthermore, our disruptor approach may open up a new avenue for developing drugs to treat CF associated with a variety of mutations.