Münster University Hospital, Institute of Physiological Chemistry and Pathobiochemistry, Münster, Germany.
Pathobiology. 2010;77(4):200-9. doi: 10.1159/000295859. Epub 2010 Jul 7.
Hyaluronan, a major water binding component of the extracellular matrix, is synthesised within the cytosol and exported across the plasma membrane by the ABC-transporter MRP5 in fibroblasts. Although its synthesis is vital for embryogenesis, MRP5-deficient mice are without phenotype, suggesting that another transporter had substituted for the MRP5 protein. Thus, we searched for a compensatory exporter in fibroblasts from MRP5 deficient mice and found that cystic fibrosis transmembrane conductance regulator (CFTR) mRNA was upregulated.
Hyaluronan export was measured in cell culture. The CFTR transporter was knocked out using si-RNA. Blockers of the ABC-transporter family were used to ascertain the hyaluronan transport capabilities functionally.
CFTR specific siRNA inhibited hyaluronan export. The tetrasaccharide was exported in undegraded form only from normal human epithelial cells and not from human epithelial cells carrying DeltaF508 CFTR. The CFTR inhibitors GlyH-101 and CFTR(172) reduced hyaluronan export from CFTR-expressing mouse fibroblasts and from human breast cancer cell lines. Bronchial secretions from patients with cystic fibrosis that consist mainly of necrotic epithelia contained at least 40-fold higher concentration of hyaluronan than secretions from patients with acute bronchitis.
CFTR transports hyaluronan across the plasma membrane of epithelial cells and this transport mechanism is defective in cystic fibrosis patients.
透明质酸是细胞外基质的主要水结合成分，在细胞质内合成，并通过成纤维细胞中的 ABC 转运蛋白 MRP5 跨质膜输出。虽然其合成对胚胎发生至关重要，但 MRP5 缺陷小鼠没有表型，这表明另一种转运蛋白替代了 MRP5 蛋白。因此，我们在 MRP5 缺陷小鼠的成纤维细胞中寻找代偿性输出蛋白，发现囊性纤维化跨膜电导调节因子 (CFTR)mRNA 上调。
在细胞培养中测量透明质酸的输出。使用 si-RNA 敲除 CFTR 转运蛋白。使用 ABC 转运蛋白家族的抑制剂来确定透明质酸的转运能力。
CFTR 特异性 siRNA 抑制透明质酸的输出。四糖仅从正常的人上皮细胞中以未降解的形式输出，而从携带 DeltaF508 CFTR 的人上皮细胞中则不能。CFTR 抑制剂 GlyH-101 和 CFTR(172) 减少了 CFTR 表达的小鼠成纤维细胞和人乳腺癌细胞系中透明质酸的输出。主要由坏死上皮组成的囊性纤维化患者的支气管分泌物中的透明质酸浓度至少比急性支气管炎患者的分泌物高 40 倍。
CFTR 跨上皮细胞的质膜转运透明质酸，这种转运机制在囊性纤维化患者中存在缺陷。
