Poschet J F, Boucher J C, Tatterson L, Skidmore J, Van Dyke R W, Deretic V
Department of Microbiology and Immunology University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Proc Natl Acad Sci U S A. 2001 Nov 20;98(24):13972-7. doi: 10.1073/pnas.241182598.
The CFTR gene encodes a transmembrane conductance regulator, which is dysfunctional in patients with cystic fibrosis (CF). The mechanism by which defective CFTR (CF transmembrane conductance regulator) leads to undersialylation of plasma membrane glycoconjugates, which in turn promote lung pathology and colonization with Pseudomonas aeruginosa causing lethal bacterial infections in CF, is not known. Here we show by ratiometric imaging with lumenally exposed pH-sensitive green fluorescent protein that dysfunctional CFTR leads to hyperacidification of the trans-Golgi network (TGN) in CF lung epithelial cells. The hyperacidification of TGN, glycosylation defect of plasma membrane glycoconjugates, and increased P. aeruginosa adherence were corrected by incubating CF respiratory epithelial cells with weak bases. Studies with pharmacological agents indicated a role for sodium conductance, modulated by CFTR regulatory function, in determining the pH of TGN. These studies demonstrate the molecular basis for defective glycosylation of lung epithelial cells and bacterial pathogenesis in CF, and suggest a cure by normalizing the pH of intracellular compartments.
CFTR基因编码一种跨膜传导调节因子，在囊性纤维化（CF）患者中该因子功能失调。有缺陷的CFTR（囊性纤维化跨膜传导调节因子）导致质膜糖缀合物唾液酸化不足，进而促进肺部病变以及铜绿假单胞菌定植，最终在CF患者中引发致命的细菌感染，但其具体机制尚不清楚。在此，我们通过使用腔内暴露的pH敏感绿色荧光蛋白进行比率成像显示，功能失调的CFTR会导致CF肺上皮细胞中转高尔基体网络（TGN）过度酸化。用弱碱孵育CF呼吸道上皮细胞可纠正TGN的过度酸化、质膜糖缀合物的糖基化缺陷以及铜绿假单胞菌黏附增加的问题。使用药物制剂的研究表明，由CFTR调节功能调节的钠电导在决定TGN的pH值方面发挥作用。这些研究证明了CF中肺上皮细胞糖基化缺陷和细菌发病机制的分子基础，并提出通过使细胞内区室的pH值正常化来进行治疗。
