Characterization of an inhibitory protein complex for cystic fibrosis therapy

描述(申请人提供)：囊性纤维化(CF)是一种致命性常染色体隐性遗传病，由突变引起的囊性纤维化跨膜电导调节(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+致病突变中，c.1521_1523delCTT(F508del)是最常见的突变，与严重的CF病相关。与F508del相关的CF的理想治疗方法需要增加细胞表面的蛋白质数量，以加强受损的通道门控特性并提高蛋白质的稳定性。对患有F508del的CF患者进行的临床试验显示，使用VX-809(CFTR校正器)和iVacaftor(CFTR增强剂)的组合方法显著改善了研究对象的肺功能，这一观点得到了有希望的临床试验结果的支持。在这个计划中，我们计划研究一个先前未知的抑制蛋白复合体，该复合体包含被拯救的F508del-CFTR、Na+/H+交换调节因子-2(NHERF2)和2型溶血磷脂酸受体(LPA2)，并从药物上破坏这个复合体以增加F508del-CFTR的通道功能。有待检验的统一假说是：(I)被拯救的F508del-CFTR与野生型CFTR一样，在质膜上与NHERF2和LPA2形成抑制复合体；(Ii)通过特定干扰NHERF2-LPA2相互作用来破坏该复合体，将增强F508del-CFTR的通道功能；(Iii)由于NHERF2-LPA2相互作用被破坏的分子机制独立于VX-809或VX-770的作用，NHERF2-LPA2抑制剂可以与VX-809和VX-770对F508del-CFTR通道功能的增强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F508del-CFTR通道功能的蛋白质复合体，而且还将提供一种通过取消这种抑制信号来增强F508del-CFTR通道功能的新方法。由于除了F508del外，其他各种CFTR突变也可以与NHERF2和LPA2形成复合体，因此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F508del-CFTR在细胞表面的病理生物学。此外，我们的干扰方法可能会为开发治疗与各种突变相关的CF的药物开辟一条新的途径。

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.