European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy.
Autophagy. 2012 Nov;8(11):1657-72. doi: 10.4161/auto.21483. Epub 2012 Aug 9.
Channel activators (potentiators) of cystic fibrosis (CF) transmembrane conductance regulator (CFTR), can be used for the treatment of the small subset of CF patients that carry plasma membrane-resident CFTR mutants. However, approximately 90% of CF patients carry the misfolded ΔF508-CFTR and are poorly responsive to potentiators, because ΔF508-CFTR is intrinsically unstable at the plasma membrane (PM) even if rescued by pharmacological correctors. We have demonstrated that human and mouse CF airways are autophagy deficient due to functional sequestration of BECN1 and that the tissue transglutaminase-2 inhibitor, cystamine, or antioxidants restore BECN1-dependent autophagy and reduce SQSTM1/p62 levels, thus favoring ΔF508-CFTR trafficking to the epithelial surface. Here, we investigated whether these treatments could facilitate the beneficial action of potentiators on ΔF508-CFTR homozygous airways. Cystamine or the superoxide dismutase (SOD)/catalase-mimetic EUK-134 stabilized ΔF508-CFTR at the plasma membrane of airway epithelial cells and sustained the expression of CFTR at the epithelial surface well beyond drug withdrawal, overexpressing BECN1 and depleting SQSTM1. This facilitates the beneficial action of potentiators in controlling inflammation in ex vivo ΔF508-CFTR homozygous human nasal biopsies and in vivo in mouse ΔF508-CFTR lungs. Direct depletion of Sqstm1 by shRNAs in vivo in ΔF508-CFTR mice synergized with potentiators in sustaining surface CFTR expression and suppressing inflammation. Cystamine pre-treatment restored ΔF508-CFTR response to the CFTR potentiators genistein, Vrx-532 or Vrx-770 in freshly isolated brushed nasal epithelial cells from ΔF508-CFTR homozygous patients. These findings delineate a novel therapeutic strategy for the treatment of CF patients with the ΔF508-CFTR mutation in which patients are first treated with cystamine and subsequently pulsed with CFTR potentiators.
囊性纤维化跨膜电导调节因子（CFTR）通道激活剂（增强剂）可用于治疗携带质膜驻留 CFTR 突变体的小部分 CF 患者。然而，大约 90%的 CF 患者携带错误折叠的 ΔF508-CFTR，对增强剂反应不佳，因为即使被药理学校正剂拯救，ΔF508-CFTR 在质膜（PM）上也是固有不稳定的。我们已经证明，由于 BECN1 的功能隔离，人类和小鼠 CF 气道存在自噬缺陷，并且组织转谷氨酰胺酶-2 抑制剂半胱胺或抗氧化剂恢复 BECN1 依赖性自噬并降低 SQSTM1/p62 水平，从而有利于 ΔF508-CFTR 向上皮表面转运。在这里，我们研究了这些治疗方法是否可以促进增强剂对 ΔF508-CFTR 纯合气道的有益作用。半胱胺或超氧化物歧化酶（SOD）/过氧化氢酶模拟物 EUK-134 稳定气道上皮细胞质膜上的 ΔF508-CFTR，并在药物撤药后很长时间内维持 CFTR 在上皮表面的表达，过度表达 BECN1 并耗尽 SQSTM1。这促进了增强剂在控制体外 ΔF508-CFTR 纯合人鼻活检和体内 ΔF508-CFTR 小鼠中的炎症中的有益作用。体内用 shRNA 直接耗尽 Sqstm1 在 ΔF508-CFTR 小鼠中与增强剂协同作用，维持表面 CFTR 表达并抑制炎症。半胱胺预处理恢复了从 ΔF508-CFTR 纯合患者新分离的刷状鼻上皮细胞中对 CFTR 增强剂金雀异黄素、 Vrx-532 或 Vrx-770 的 ΔF508-CFTR 反应。这些发现描绘了一种治疗 CF 患者 ΔF508-CFTR 突变的新治疗策略，其中患者首先用半胱胺治疗，然后用 CFTR 增强剂脉冲治疗。
