Department of Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
Proc Natl Acad Sci U S A. 2010 Jun 22;107(25):11393-8. doi: 10.1073/pnas.0909128107. Epub 2010 Jun 8.
The endogenous signaling molecule S-nitrosoglutathione (GSNO) and other S-nitrosylating agents can cause full maturation of the abnormal gene product DeltaF508 cystic fibrosis (CF) transmembrane conductance regulator (CFTR). However, the molecular mechanism of action is not known. Here we show that Hsp70/Hsp90 organizing protein (Hop) is a critical target of GSNO, and its S-nitrosylation results in DeltaF508 CFTR maturation and cell surface expression. S-nitrosylation by GSNO inhibited the association of Hop with CFTR in the endoplasmic reticulum. This effect was necessary and sufficient to mediate GSNO-induced cell-surface expression of DeltaF508 CFTR. Hop knockdown using siRNA recapitulated the effect of GSNO on DeltaF508 CFTR maturation and expression. Moreover, GSNO acted additively with decreased temperature, which promoted mutant CFTR maturation through a Hop-independent mechanism. We conclude that GSNO corrects DeltaF508 CFTR trafficking by inhibiting Hop expression, and that combination therapies--using differing mechanisms of action--may have additive benefits in treating CF.
内源性信号分子 S-亚硝基谷胱甘肽（GSNO）和其他 S-亚硝酰化剂可使异常基因产物 DeltaF508 囊性纤维化（CF）跨膜电导调节剂（CFTR）完全成熟。然而，其作用的分子机制尚不清楚。本文中，我们发现热休克蛋白 70/90 组织蛋白酶（Hsp70/Hsp90） 伴侣蛋白（Hop）是 GSNO 的关键靶标，其 S-亚硝基化导致 DeltaF508 CFTR 成熟和细胞表面表达。GSNO 的 S-亚硝基化抑制了 Hop 与内质网中 CFTR 的结合。这种效应对于介导 GSNO 诱导的 DeltaF508 CFTR 细胞表面表达是必要且充分的。用 siRNA 敲低 Hop 可重现 GSNO 对 DeltaF508 CFTR 成熟和表达的影响。此外，GSNO 与降低温度具有相加作用，后者通过一种与 Hop 无关的机制促进突变 CFTR 成熟。我们得出结论，GSNO 通过抑制 Hop 表达来纠正 DeltaF508 CFTR 转运，使用不同作用机制的联合疗法可能在治疗 CF 方面具有相加益处。
