title: Aldosterone induces angiotensin converting enzyme gene expression via a JAK2-dependent pathway in rat endothelial cells.
abstract: Aldosterone is currently recognized as a risk hormone for cardiovascular disease. However, the cellular mechanism by which aldosterone acts on vasculature has not been well understood. In the present study, we investigated whether aldosterone affects angiotensin-converting enzyme (ACE) gene expression in rat endothelial cells. Cultured rat aortic endothelial cells (RAECs) from Sprague-Dawley rats were used in the study. ACE mRNA levels and its enzyme activities in RAECs were examined by real-time RT-PCR and enzyme assay using hippuryl-His-Leu as substrates, respectively. Aldosterone significantly increased steady-state ACE mRNA levels and its enzymatic activities. This effect was dose dependent and time dependent and abolished by mineralocorticoid receptor antagonist spironolactone or transcription inhibitor actinomycin D. Dexamethasone also increased steady-state ACE mRNA levels, whose effect was completely blocked by glucocorticoid receptor antagonist RU486, but not by spironolactone. By contrast, the aldosterone-induced ACE mRNA expression was only partially blocked by RU486. The stimulatory effect of aldosterone on ACE mRNA expression was completely blocked by a protein tyrosine kinase inhibitor (genistein) and JAK2 inhibitor (AG490), partially by Src kinase inhibitor (PP2) and epidermal growth factor receptor kinase inhibitor (AG1478), but not by platelet-derived growth factor receptor kinase inhibitor (AG1296). Transfection of dominant-negative JAK2 construct, but not wild-type construct, significantly blocked the aldosterone-induced ACE mRNA up-regulation. Furthermore, aldosterone induced phosphorylation of JAK2, whose effect was blocked by spironolactone and actinomycin D. In conclusion, the present study demonstrates for the first time that aldosterone induces ACE gene expression and its enzyme activity mainly via a mineralocorticoid receptor-mediated and JAK2-dependent pathway in rat endothelial cells. This may constitute a positive feedback loop for a local renin-angiotensin system, possibly involved in the development of aldosterone-induced endothelial dysfunction and vascular injury.
authors.affiliation: Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8513, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Takanobu
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Kyoichiro
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Naoki
authors.initials: N
authors.lastname: Gochou
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hirono
authors.forename: Toru
authors.initials: T
authors.lastname: Tateno
authors.forename: Nozomi
authors.initials: N
authors.lastname: Fukai
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Shichiri
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D053614:Janus Kinase 2; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018161:Receptors, Mineralocorticoid / Q000378:metabolism
chemical_list: D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018161:Receptors, Mineralocorticoid; D000450:Aldosterone; D011505:Protein-Tyrosine Kinases; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D007703:Peptidyl-Dipeptidase A