Interferon-gamma regulates ClC-2 chloride channel in lung epithelial cells.
Epithelial Cl(-) channels mediate Cl(-) and fluid secretion in the lung. In cystic fibrosis, aberrant Cl(-) secretion is one of the major causes for lung fluid imbalance. Regulation of Cl(-) channels is therefore an important issue in the lung. IFN-gamma regulates Na(+) and Cl(-) channels and fluid transport in the lung, but the mechanisms involved in these regulations are not clear. In expression studies, we found that IFN-gamma increased ClC-2 transcripts in Calu-3 cells. Studies of the promoter identified a minimal promoter which interacts with transcription factors Sp1 and Sp3. However, reporter gene assays showed that IFN-gamma did not activate the promoter. Instead, IFN-gamma significantly increased ClC-2 transcript stability. Using Ussing chamber experiments, we demonstrate that IFN-gamma activates a pH-regulated and Cd(2+)-sensitive short circuit current, characteristic properties of the ClC-2 Cl(-) channel. These data suggest that IFN-gamma activates ClC-2 channel activity in lung epithelial cells via mRNA stabilization.
Department of Veterans Affairs Medical Center, McGuire Research Institute, USA. schu@hsc.vcu.edu <schu@hsc.vcu.edu>
Shijian
S
Chu
Carol J
CJ
Blaisdell
Penelope
P
Bamford
Thomas J
TJ
Ferro
D000818:Animals; D000090007:CLC-2 Chloride Channels; D002104:Cadmium / Q000378:metabolism; D045744:Cell Line, Tumor; D054370:Chemokine CXCL9; D019743:Chemokines, CXC / Q000494:pharmacology; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D006863:Hydrogen-Ion Concentration; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D016753:Interleukin-10 / Q000494:pharmacology; D008168:Lung / Q000166:cytology* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism
D000090007:CLC-2 Chloride Channels; C080810:CXCL9 protein, human; D054370:Chemokine CXCL9; D019743:Chemokines, CXC; D018118:Chloride Channels; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D002104:Cadmium; D016753:Interleukin-10; D007371:Interferon-gamma