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Amiodarone Induces Angiotensinogen Gene Expression in Lung Alveolar Epithelial Cells through Activation Protein‐1
Author(s) -
Uhal Bruce D.,
Zhang Huiying,
AbdulHafez Amal,
Shu Ruijie,
Li Xiaopeng
Publication year - 2007
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/j.1742-7843.2007.00006.x
Subject(s) - luciferase , amiodarone , microbiology and biotechnology , messenger rna , chemistry , gene expression , activator (genetics) , transcription (linguistics) , endocrinology , medicine , biology , gene , transfection , biochemistry , linguistics , philosophy , atrial fibrillation
Previous work from this laboratory has shown that amiodarone induces alveolar epithelial cell apoptosis that was abrogated by antagonists of angiotensin II. In this study, amiodarone up‐regulated angiotensinogen mRNA and protein in primary cultures of rat type II pneumocytes and in the human A549 cell line. The mechanism of amiodarone‐induced angiotensinogen expression was studied in A549 cells with a human angiotensinogen promoter‐luciferase reporter (angiotensinogen/luciferase). Amiodarone (3 µg/ml) induced both angiotensinogen/luciferase and endogenous angiotensinogen mRNA; the latter was completely blocked by actinomycin‐D. Amiodarone did not affect the half‐life of endogenous angiotensinogen mRNA. Deletion analyses of angiotensinogen/luciferase identified at least two amiodarone‐responsive domains in the angiotensinogen promoter between −350 to −260 bp and −203 to −46 bp. DNA/Protein array and electrophoretic mobility shift assays showed that amiodarone increases DNA binding of both activation protein‐1 and STAT‐5 transcription factors. Site‐directed mutagenesis of three IL‐6‐responsive signal transducer activator of transcription (STAT) binding sites within the amiodarone‐response domains had no effect on amiodarone‐induced angiotensinogen/luciferase expression. In contrast, amiodarone‐induced angiotensinogen/luciferase expression was abrogated by a dominant‐negative fos construct and was stimulated over five times by c‐fos and c‐jun expressed together but not separately. Mutagenesis of the activation protein‐1 binding site at −15 to −12 bp completely eliminated the response to amiodarone. These data show that activation protein‐1 family transcription factors mediate amiodarone‐induced angiotensinogen expression in human alveolar epithelial cells and identify an activation protein‐1 site, located between the TATA (DNA sequence) box and the transcription initiation site, that is required for the response.