title: [Polymethoxylated flavonoids activate cystic fibrosis transmembrane conductance regulator chloride channel].
abstract: Cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent chloride channel, plays key roles in fluid secretion in serous epithelial cells. Previously, we identified two polymethoxylated flavonoids, 3',4',5,5',6,7-hexamethoxyflavone (HMF) and 5-hydroxy-6,7,3',4'-tetramethoxyflavone (HTF) which could potentiate CFTR chloride channel activities. The present study was aimed to investigate the potentiation effects of HMF and HTF on CFTR Cl(-) channel activities by using a cell-based fluorescence assay and the short circuit Ussing chamber assay. The results of cell-based fluorescence assay showed that both HMF and HTF could dose-dependently potentiate CFTR Cl(-) channel activities in rapid and reversible ways, and the activations could be reversed by the CFTR blocker CFTRinh-172. Notably, HMF showed the highest affinity (EC50 = 2 μmol/L) to CFTR protein among the flavonoid CFTR activators identified so far. The activation of CFTR by HMF or HTF was forskolin (FSK) dependent. Both compounds showed additive effect with FSK and 3-Isobutyl-1-methylx (IBMX) in the activation of CFTR, while had no additive effect with genistein (GEN). In ex vivo studies, HMF and HTF could stimulate transepithelial Cl(-) secretion in rat colonic mucosa and enhance fluid secretion in mouse trachea submucosal glands. These results suggest that HMF and HTF may potentiate CFTR Cl(-) channel activities through both elevation of cAMP level and binding to CFTR protein pathways. The results provide new clues in elucidating structure and activity relationship of flavonoid CFTR activators. HMF might be developed as a new drug in the therapy of CFTR-related diseases such as bronchiectasis and habitual constipation.
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China.
authors.forename: Huan-Huan
authors.initials: HH
authors.lastname: Cao
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Luan
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: College of Life Sciences, Liaoning Normal University, Dalian 116081, China. hyanglnnu@gmail.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
mesh_terms: D000818:Animals; D005576:Colforsin; D003106:Colon / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects*; D047309:Flavones / Q000502:physiology; D005419:Flavonoids / Q000494:pharmacology*; D019833:Genistein; D007413:Intestinal Mucosa / Q000378:metabolism; D051379:Mice; D051381:Rats
chemical_list: C000590666:5-hydroxy-6,7,3',4'-tetramethoxyflavone; D047309:Flavones; D005419:Flavonoids; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; C008661:nobiletin; D019833:Genistein