Cui Guiying, Cottrill Kirsten A, Strickland Kerry M, Mashburn Sarah A, Koval Michael, McCarty Nael A
Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA, United States.
Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA, United States.
Front Physiol. 2021 Jun 7;12:652513. doi: 10.3389/fphys.2021.652513. eCollection 2021.
Altered cholesterol homeostasis in cystic fibrosis patients has been reported, although controversy remains. As a major membrane lipid component, cholesterol modulates the function of multiple ion channels by complicated mechanisms. However, whether cholesterol directly modulates cystic fibrosis transmembrane conductance regulator (CFTR) channel function remains unknown. To answer this question, we determined the effects of changing plasma membrane cholesterol levels on CFTR channel function utilizing polarized fischer rat thyroid (FRT) cells and primary human bronchial epithelial (HBE) cells. Treatment with methyl-β-cyclodextrin (MβCD) significantly reduced total cholesterol content in FRT cells, which significantly decreased forskolin (FSK)-mediated activation of both wildtype (WT-) and P67L-CFTR. This effect was also seen in HBE cells expressing WT-CFTR. Cholesterol modification by cholesterol oxidase and cholesterol esterase also distinctly affected activation of CFTR by FSK. In addition, alteration of cholesterol increased the potency of VX-770, a clinically used potentiator of CFTR, when both WT- and P67L-CFTR channels were activated at low FSK concentrations; this likely reflects the apparent shift in the sensitivity of WT-CFTR to FSK after alteration of membrane cholesterol. These results demonstrate that changes in the plasma membrane cholesterol level significantly modulate CFTR channel function and consequently may affect sensitivity to clinical therapeutics in CF patients.
尽管仍存在争议，但已有报道称囊性纤维化患者的胆固醇稳态发生了改变。作为主要的膜脂成分，胆固醇通过复杂的机制调节多种离子通道的功能。然而，胆固醇是否直接调节囊性纤维化跨膜传导调节因子（CFTR）通道功能仍不清楚。为了回答这个问题，我们利用极化的 Fischer 大鼠甲状腺（FRT）细胞和原代人支气管上皮（HBE）细胞，确定了改变质膜胆固醇水平对 CFTR 通道功能的影响。用甲基-β-环糊精（MβCD）处理显著降低了 FRT 细胞中的总胆固醇含量，这显著降低了福斯可林（FSK）介导的野生型（WT-）和 P67L-CFTR 的激活。在表达 WT-CFTR 的 HBE 细胞中也观察到了这种效应。胆固醇氧化酶和胆固醇酯酶对胆固醇的修饰也明显影响了 FSK 对 CFTR 的激活。此外，当 WT-和 P67L-CFTR 通道在低 FSK 浓度下被激活时，胆固醇的改变增加了临床上使用的 CFTR 增强剂 VX-770 的效力；这可能反映了膜胆固醇改变后 WT-CFTR 对 FSK 敏感性的明显变化。这些结果表明，质膜胆固醇水平的变化显著调节 CFTR 通道功能，因此可能影响 CF 患者对临床治疗的敏感性。
