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NFATc3 mediates Chronic Hypoxia (CH)‐induced soluble guanylyl cyclase‐α (sGC‐α) up‐regulation in the lung
Author(s) -
de Frutos Garcia Sergio,
Spangler Rhyan,
Alò Dominique,
Bosc Laura Gonzalez
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1414
Subject(s) - nfat , luciferase , ionomycin , microbiology and biotechnology , chemistry , transcription factor , pharmacology , medicine , endocrinology , transfection , biology , biochemistry , calcium , gene
Lung sGC‐α is up‐regulated during CH‐induced pulmonary hypertension, suggesting its importance in the regulation of pulmonary arterial pressure and pulmonary artery (PA) tone. Since PA Ca 2+ is elevated during CH, we investigated the role of the Ca 2+ ‐dependent transcription factor NFATc3 in CH‐induced up‐regulation of sGC‐α. NFAT‐luciferase reporter mice were exposed to normoxia (N, 630 torr) or CH (380 torr) for 2, 7 and 21 days. Exposure to CH elicited a significant (p<0.05) increase in luciferase activity in PA at all studied times demonstrating that CH activates NFAT (1.4± 0.2; 3.9±0.7; 2.9±0.2; 2.5±0.20, n=5). In addition, luciferase did not increase in PA from NFAT‐luc/NFATc3 −/− mice exposed to CH. As expected, CH‐induced an increase in lung sGC‐α protein levels (immunoblot), and both NFAT inhibition (cyclosporin A, CsA, 25 mg/Kg/day) and genetic deletion of NFATc3 prevented that increase (WT: 100.0 ± 4.9, KO: 74.4 ± 23.0, CH WT: 169.1 ± 16.3, CH KO: 61.3 ± 9.9). Consistent with these findings, we identified an NFAT binding site in the sGC‐α promoter. Therefore, HEK cells were co‐transfected with a luciferase reporter plasmid containing the promoter region of the sGC‐α and an NFATc3 expression vector. Luciferase significantly increased after NFATc3 was activated with 1 μM Ionomycin (% change: 131.4 ± 4.2, n=7). This activation was completely prevented by pretreatment with CsA and an NFAT dominant negative, suggesting that NFATc3 regulates sGC‐α expression. In conclusion, CH activates NFATc3 which mediates CH‐induced up‐regulation of sGC‐α by increasing promoter activity.