title: Regulation and function of the two-pore-domain (K2P) potassium channel Trek-1 in alveolar epithelial cells.
abstract: Hyperoxia can lead to a myriad of deleterious effects in the lung including epithelial damage and diffuse inflammation. The specific mechanisms by which hyperoxia promotes these pathological changes are not completely understood. Activation of ion channels has been proposed as one of the mechanisms required for cell activation and mediator secretion. The two-pore-domain K(+) channel (K2P) Trek-1 has recently been described in lung epithelial cells, but its function remains elusive. In this study we hypothesized that hyperoxia affects expression of Trek-1 in alveolar epithelial cells and that Trek-1 is involved in regulation of cell proliferation and cytokine secretion. We found gene expression of several K2P channels in mouse alveolar epithelial cells (MLE-12), and expression of Trek-1 was significantly downregulated in cultured cells and lungs of mice exposed to hyperoxia. Similarly, proliferation cell nuclear antigen (PCNA) and Cyclin D1 expression were downregulated by exposure to hyperoxia. We developed an MLE-12 cell line deficient in Trek-1 expression using shRNA and found that Trek-1 deficiency resulted in increased cell proliferation and upregulation of PCNA but not Cyclin D1. Furthermore, IL-6 and regulated on activation normal T-expressed and presumably secreted (RANTES) secretion was decreased in Trek-1-deficient cells, whereas release of monocyte chemoattractant protein-1 was increased. Release of KC/IL-8 was not affected by Trek-1 deficiency. Overall, deficiency of Trek-1 had a more pronounced effect on mediator secretion than exposure to hyperoxia. This is the first report suggesting that the K(+) channel Trek-1 could be involved in regulation of alveolar epithelial cell proliferation and cytokine secretion, but a direct association with hyperoxia-induced changes in Trek-1 levels remains elusive.
authors.affiliation: Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee 38111, USA. aschwing@uthsc.edu
authors.forename: Andreas
authors.initials: A
authors.lastname: Schwingshackl
authors.forename: Bin
authors.initials: B
authors.lastname: Teng
authors.forename: Manik
authors.initials: M
authors.lastname: Ghosh
authors.forename: Alina Nico
authors.initials: AN
authors.lastname: West
authors.forename: Patrudu
authors.initials: P
authors.lastname: Makena
authors.forename: Vijay
authors.initials: V
authors.lastname: Gorantla
authors.forename: Scott E
authors.initials: SE
authors.lastname: Sinclair
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Waters
mesh_terms: D056809:Alveolar Epithelial Cells / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D018496:Hyperoxia / Q000235:genetics / Q000503:physiopathology*; D018836:Inflammation Mediators / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D024683:Potassium Channels, Tandem Pore Domain / Q000172:deficiency / Q000235:genetics; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology*
chemical_list: C503460:Ccl5 protein, mouse; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D018836:Inflammation Mediators; D015850:Interleukin-6; D016209:Interleukin-8; D024683:Potassium Channels, Tandem Pore Domain; D018809:Proliferating Cell Nuclear Antigen; C103742:potassium channel protein TREK-1; D019938:Cyclin D1