Rac1 GTPase regulates 11β hydroxysteroid dehydrogenase type 2 and fibrotic remodeling.
The aim of the study was to characterize the role of Rac1 GTPase for the mineralocorticoid receptor (MR)-mediated pro-fibrotic remodeling. Transgenic mice with cardiac overexpression of constitutively active Rac1 (RacET) develop an age-dependent phenotype with atrial dilatation, fibrosis, and atrial fibrillation. Expression of MR was similar in RacET and WT mice. The expression of 11β hydroxysteroid dehydrogenase type 2 (11β-HSD2) was age-dependently up-regulated in the atria and the left ventricles of RacET mice on mRNA and protein levels. Statin treatment inhibiting Rac1 geranylgeranylation reduced 11β-HSD2 up-regulation. Samples of human left atrial myocardium showed a positive correlation between Rac1 activity and 11β-HSD2 expression (r= 0.7169). Immunoprecipitation showed enhanced Rac1-bound 11β-HSD2 relative to Rac1 expression in RacET mice that was diminished with statin treatment. Both basal and phorbol 12-myristate 13-acetate (PMA)-induced NADPH oxidase activity were increased in RacET and correlated positively with 11β-HSD2 expression (r= 0.788 andr= 0.843, respectively). In cultured H9c2 cardiomyocytes, Rac1 activation with l-buthionine sulfoximine increased; Rac1 inhibition with NSC23766 decreased 11β-HSD2 mRNA and protein expression. Connective tissue growth factor (CTGF) up-regulation induced by aldosterone was prevented with NSC23766. Cardiomyocyte transfection with 11β-HSD2 siRNA abolished the aldosterone-induced CTGF up-regulation. Aldosterone-stimulated MR nuclear translocation was blocked by the 11β-HSD2 inhibitor carbenoxolone. In cardiac fibroblasts, nuclear MR translocation induced by aldosterone was inhibited with NSC23766 and spironolactone. NSC23766 prevented the aldosterone-induced proliferation and migration of cardiac fibroblasts and the up-regulation of CTGF and fibronectin. In conclusion, Rac1 GTPase regulates 11β-HSD2 expression, MR activation, and MR-mediated pro-fibrotic signaling.
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany daniel.lavall@uks.eu.
Daniel
D
Lavall
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany.
Pia
P
Schuster
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany.
Nadine
N
Jacobs
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany.
Andrey
A
Kazakov
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany.
Michael
M
Böhm
From the Universität des Saarlandes, Klinik für Innere Medizin III-Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, D-66421 Homburg/Saar, Germany.
Ulrich
U
Laufs
D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000096:biosynthesis* / Q000235:genetics; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D055513:Connective Tissue Growth Factor / Q000096:biosynthesis / Q000235:genetics; D004719:Endomyocardial Fibrosis / Q000201:enzymology* / Q000473:pathology; D005347:Fibroblasts / Q000201:enzymology* / Q000473:pathology; D005353:Fibronectins / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008715:Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D008817:Mice, Mutant Strains; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000473:pathology; D009479:Neuropeptides / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013454:Sulfoxides / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis* / Q000235:genetics
C526317:CCN2 protein, human; C526318:CCN2 protein, mouse; C526316:CCN2 protein, rat; D005353:Fibronectins; D009479:Neuropeptides; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; D013454:Sulfoxides; C000594507:buthionine sulfoxide; D055513:Connective Tissue Growth Factor; D000450:Aldosterone; D008715:Methionine; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein; D013755:Tetradecanoylphorbol Acetate
11β hydroxysteroid dehydrogenase type 2; Rac (Rac GTPase); Rac1; aldosterone; connective tissue growth factor (CTGF); fibrosis; mineralocorticoid receptor