title: Quercetin stimulates Na+/K+/2Cl- cotransport via PTK-dependent mechanisms in human airway epithelium.
abstract: We investigated regulatory mechanisms of Cl(-) secretion playing an essential role in the maintenance of surface fluid in human airway epithelial Calu-3 cells. The present study reports that quercetin (a flavonoid) stimulated bumetanide-sensitive Cl(-) secretion with reduction of apical Cl(-) conductance, suggesting that quercetin stimulates Cl(-) secretion by activating an entry step of Cl(-) across the basolateral membrane through Na(+)/K(+)/2Cl(-) cotransporter (NKCC1). To clarify the mechanism stimulating NKCC1 by quercetin, we verified involvement of protein kinase (PK)A, PKC, protein tyrosine kinase (PTK), and cytosolic Ca(2+)-dependent pathways. A PKA inhibitor (PKI-14-22 amide), a PKC inhibitor (Gö 6983) or a Ca(2+) chelating agent did not affect the quercetin-stimulated Cl(-) secretion. On the other hand, a PTK inhibitor (AG18) significantly diminished the stimulatory action of quercetin on Cl(-) secretion without inhibitory effects on apical Cl(-) conductance, suggesting that a PTK-mediated pathway is involved in the stimulatory action of quercetin. The quercetin action on Cl(-) secretion was suppressed with brefeldin A (BFA, an inhibitor of vesicular transport from ER to Golgi), and the BFA-sensitive Cl(-) secretion was not observed in the presence of an epidermal growth factor receptor (EGFR) kinase inhibitor (AG1478), suggesting that quercetin stimulates Cl(-) secretion by causing the EGFR kinase-mediated translocation of NKCC1 or an NKC1-activating factor to the basolateral membrane in human airway epithelial Calu-3 cells. However, the surface density of NKCC1 was not increased by quercetin, but quercetin elevated the activity of NKCC1. These observations indicate that quercetin stimulates Cl(-) secretion by activating NKCC1 via translocation of an NKCC1-activating factor through an EGFR kinase-dependent pathway.
authors.affiliation: Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Asano
authors.forename: Naomi
authors.initials: N
authors.lastname: Niisato
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Nakajima
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Yasuda
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Takemitsu
authors.initials: T
authors.lastname: Hama
authors.forename: Kenji
authors.initials: K
authors.lastname: Dejima
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Hisa
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Marunaka
mesh_terms: D020126:Brefeldin A / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011794:Quercetin / Q000494:pharmacology*; D011799:Quinazolines; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism*; D064506:Solute Carrier Family 12, Member 2; D020032:Tyrphostins / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D002712:Chlorides; D004791:Enzyme Inhibitors; D011799:Quinazolines; C578877:SLC12A2 protein, human; D049994:Sodium Potassium Chloride Symporter Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D020032:Tyrphostins; D002034:Bumetanide; C101044:RTKI cpd; D014634:Valinomycin; D020126:Brefeldin A; D011794:Quercetin; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases