Manzanares Dahis, Krick Stefanie, Baumlin Nathalie, Dennis John S, Tyrrell Jean, Tarran Robert, Salathe Matthias
From the Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida 33136 and.
Cystic Fibrosis Center, University of North Carolina, Chapel Hill, North Carolina 27599.
J Biol Chem. 2015 Oct 16;290(42):25710-6. doi: 10.1074/jbc.M115.670885. Epub 2015 Sep 3.
Transforming growth factor β1 (TGF-β1) is not only elevated in airways of cystic fibrosis (CF) patients, whose airways are characterized by abnormal ion transport and mucociliary clearance, but TGF-β1 is also associated with worse clinical outcomes. Effective mucociliary clearance depends on adequate airway hydration, governed by ion transport. Apically expressed, large-conductance, Ca(2+)- and voltage-dependent K(+) (BK) channels play an important role in this process. In this study, TGF-β1 decreased airway surface liquid volume, ciliary beat frequency, and BK activity in fully differentiated CF bronchial epithelial cells by reducing mRNA expression of the BK γ subunit leucine-rich repeat-containing protein 26 (LRRC26) and its function. Although LRRC26 knockdown itself reduced BK activity, LRRC26 overexpression partially reversed TGF-β1-induced BK dysfunction. TGF-β1-induced airway surface liquid volume hyper-absorption was reversed by the BK opener mallotoxin and the clinically useful TGF-β signaling inhibitor pirfenidone. The latter increased BK activity via rescue of LRRC26. Therefore, we propose that TGF-β1-induced mucociliary dysfunction in CF airways is associated with BK inactivation related to a LRRC26 decrease and is amenable to treatment with clinically useful TGF-β1 inhibitors.
转化生长因子β1(TGF-β1)不仅在囊性纤维化(CF)患者的气道中升高,这些患者的气道具有异常离子转运和黏液纤毛清除功能的特征,而且TGF-β1还与更差的临床结果相关。有效的黏液纤毛清除取决于由离子转运控制的充足气道水合作用。顶端表达的大电导、钙和电压依赖性钾(BK)通道在此过程中起重要作用。在本研究中,TGF-β1通过降低BKγ亚基富含亮氨酸重复序列蛋白26(LRRC26)的mRNA表达及其功能,降低了完全分化的CF支气管上皮细胞中的气道表面液体量、纤毛摆动频率和BK活性。虽然LRRC26敲低本身降低了BK活性,但LRRC26过表达部分逆转了TGF-β1诱导的BK功能障碍。BK开放剂马洛毒素和临床上有用的TGF-β信号抑制剂吡非尼酮逆转了TGF-β1诱导的气道表面液体量过度吸收。后者通过挽救LRRC26增加了BK活性。因此,我们提出,TGF-β1诱导的CF气道黏液纤毛功能障碍与LRRC26减少相关的BK失活有关,并且可用临床上有用的TGF-β1抑制剂进行治疗。