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: Andreas Schwingshackl, Bin Teng, Manik Ghosh, Alina Nico West, Patrudu Makena, Vijay Gorantla, Scott E Sinclair, Christopher M Waters
• Journal: American journal of physiology. Lung cellular and molecular physiology (Am J Physiol Lung Cell Mol Physiol) Vol. 302 Issue 1 Pg. L93-L102 (Jan 01 2012) ISSN: 1522-1504 [Electronic] United States
• PMID: 21949155 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Ccl5 protein, mouse
• Chemokine CCL2
• Chemokine CCL5
• Inflammation Mediators
• Interleukin-6
• Interleukin-8
• Potassium Channels, Tandem Pore Domain
• Proliferating Cell Nuclear Antigen
• potassium channel protein TREK-1
• Cyclin D1

Topics

• Alveolar Epithelial Cells (metabolism)
• Animals
• Cell Line
• Cell Proliferation
• Chemokine CCL2 (genetics, metabolism)
• Chemokine CCL5 (metabolism)
• Cyclin D1 (genetics, metabolism)
• Hyperoxia (genetics, physiopathology)
• Inflammation Mediators (metabolism)
• Interleukin-6 (genetics, metabolism)
• Interleukin-8 (genetics, metabolism)
• Male
• Mice
• Mice, Inbred C57BL
• Microscopy, Confocal
• Potassium Channels, Tandem Pore Domain (deficiency, genetics)
• Proliferating Cell Nuclear Antigen (genetics, metabolism)
• Pulmonary Alveoli (cytology)