Zhang Y, Doranz B, Yankaskas J R, Engelhardt J F
Department of Molecular and Cellular Engineering, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
J Clin Invest. 1995 Dec;96(6):2997-3004. doi: 10.1172/JCI118372.
Intracellular dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) has been proposed to alter endosomal acidification. The most widely studied consequence of this defect has been alterations in the biochemical properties of cystic fibrosis (CF) respiratory mucus glycoproteins. However, studies confirming the existence of mucous processing defects in CF have been hindered by the lack of in vivo animal models by which to test these hypotheses in the absence of secondary effects of chronic bacterial infection. The human bronchial xenograft model has been useful in evaluating the pathophysiologic differences between CF and non-CF airway epithelium, in the absence of secondary disease effects such as goblet cell hyperplasia. In this study we sought to compare the extent of sulfation within secreted mucus glycoproteins from CF and non-CF human bronchial xenografts. Cumulative results of xenografts generated from 13 independent CF tissue samples demonstrated a statistically significant higher level of sulfation (1.7 +/- 0.18, P < 0.026) as compared to non-CF paired controls. Such findings add to the growing body of knowledge that primary defects in sulfation exist in CF respiratory mucin. Correlation of genotype with the extent of mucus sulfation revealed two categories of CF tissues with statistically different mucus sulfation profiles. Results from these studies demonstrated a 2.0 +/- 0.15-fold higher level of mucus sulfation produced from xenografts of five defined CF genotypes as compared to non-CF controls (P < 0.004, n= 10). Interestingly, three CF samples for which one mutant allele remained undefined (deltaoff8/unknown or G551D/unknown) demonstrated no statistical difference in the level of sulfation as compared with matched non-CF controls (n= 3). This as yet unknown allele was not identified within a screen for the 26 most common CF mutations. These results provide preliminary evidence for allelic variation within the CF population which may begin to elucidate the structure-function of CFTR with regards to intracellular mucus processing defects.
有人提出囊性纤维化跨膜传导调节因子（CFTR）的细胞内功能障碍会改变内体酸化。这种缺陷最广泛研究的后果是囊性纤维化（CF）呼吸道黏液糖蛋白的生化特性发生改变。然而，由于缺乏在无慢性细菌感染继发效应的情况下测试这些假设的体内动物模型，证实CF中存在黏液加工缺陷的研究受到了阻碍。人支气管异种移植模型在评估CF和非CF气道上皮之间的病理生理差异方面很有用，且不存在杯状细胞增生等继发疾病效应。在本研究中，我们试图比较CF和非CF人支气管异种移植分泌的黏液糖蛋白中的硫酸化程度。来自13个独立CF组织样本的异种移植累积结果表明，与非CF配对对照相比，硫酸化水平在统计学上显著更高（1.7±0.18，P<0.026）。这些发现增加了越来越多的知识，即CF呼吸道黏蛋白中存在硫酸化的原发性缺陷。基因型与黏液硫酸化程度的相关性揭示了两类CF组织，其黏液硫酸化谱在统计学上不同。这些研究结果表明，与非CF对照相比，五种确定的CF基因型的异种移植产生的黏液硫酸化水平高2.0±0.15倍（P<0.004，n = 10）。有趣的是，三个一个突变等位基因仍未确定的CF样本（deltaoff8/未知或G551D/未知）与匹配的非CF对照相比，硫酸化水平没有统计学差异（n = 3）。在对26种最常见的CF突变进行的筛查中未发现这个尚未确定的等位基因。这些结果为CF人群中的等位基因变异提供了初步证据，这可能开始阐明CFTR在细胞内黏液加工缺陷方面的结构功能。
