A Small Molecule That Binds to an ATPase Domain of Hsc70 Promotes Membrane Trafficking of Mutant Cystic Fibrosis Transmembrane Conductance Regulator
A Small Molecule That Binds to an ATPase Domain of Hsc70 Promotes Membrane Trafficking of Mutant Cystic Fibrosis Transmembrane Conductance Regulator
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DOI：
10.1021/ja206762p
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发表时间：
2011-12-21
影响因子：
15
通讯作者：
Shin, Injae
中科院分区：
文献类型：
--
作者：
Cho, Hyungseoph J.;Gee, Heon Yung;Shin, Injae
囊性纤维化跨膜电导调节因子(CFTR)是一种细胞-表面阴离子通道，能渗透氯离子和碳酸氢根离子。导致囊性纤维化的最常见的CFTR突变是508位苯丙氨酸(Delta F508)的缺失，导致蛋白质折叠和细胞向质膜转运的缺陷。由于慢性肺部感染导致肺功能进行性恶化，细胞表面CFTR的缺乏导致寿命缩短。Hsc70在泛素-蛋白酶体系统降解突变的cftr中起着至关重要的作用。到目前为止，各种Hsc70抑制剂和转录调节剂已经被测试以确定它们是否能纠正突变的CFTR的活性缺陷，然而，它们在恢复囊性纤维化细胞的氯离子通道活性方面表现出有限的或可疑的作用。在此，我们证明了小分子凋亡唑(Az)在囊性纤维化细胞中具有促进突变的CFTR的膜转运及其氯离子通道活性的高细胞效力。亲和层析和ATPase活性测定结果表明，Az通过与Hsc70的ATPase结构域结合而抑制其ATPase活性。此外，配体导向的蛋白质标记和分子模拟研究也表明Az与ATPase结构域结合，特别是ATP结合口袋。推测Az可能通过阻断突变体与Hsc70和ChIP的相互作用来抑制Delta F508-CFTR的泛素化，从而增强突变体的膜转运。
Cystic fibrosis transmembrane conductance regulator (CFTR) is a cell-surface anion channel that permeates chloride and bicarbonate ions. The most frequent mutation of CFTR that causes cystic fibrosis is the deletion of phenylalanine at position 508 (Delta F508), which leads to defects in protein folding and cellular trafficking to the plasma membrane. The lack of the cell-surface CFTR results in a reduction in the lifespan due to chronic lung infection with progressive deterioration of lung function. Hsc70 plays a crucial role in degradation of mutant CFTR by the ubiquitin-proteasome system. To date, various Hsc70 inhibitors and transcription regulators have been tested to determine whether they correct the defective activity of mutant CFTR However, they exhibited limited or questionable effects on restoring the chloride channel activity in cystic fibrosis cells. Herein, we show that a small molecule apoptozole (Az) has high cellular potency to promote membrane trafficking of mutant CFTR and its chloride channel activity in cystic fibrosis cells. Results from affinity chromatography and ATPase activity assay indicate that Az inhibits the ATPase activity of Hsc70 by binding to its ATPase domain. In addition, a ligand-directed protein labeling and molecular modeling studies also suggest the binding of Az to an ATPase domain, in particular, an ATP-binding pocket. It is proposed that Az suppresses ubiquitination of Delta F508-CFTR maybe by blocking interaction of the mutant with Hsc70 and CHIP, and, as a consequence, it enhances membrane trafficking of the mutant.