Rac1 GTPase regulates 11β hydroxysteroid dehydrogenase type 2 and fibrotic remodeling
Rac1 GTPase regulates 11β hydroxysteroid dehydrogenase type 2 and fibrotic remodeling
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DOI：
10.1074/jbc.m116.764449
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发表时间：
2017-05-05
影响因子：
4.8
通讯作者：
Laufs, Ulrich
中科院分区：
文献类型：
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作者：
Lavall, Daniel;Schuster, Pia;Laufs, Ulrich
本研究的目的是表征Rac1 GTPase在矿糖皮质激素受体（MR）介导的促纤维化重塑中的作用。心脏过表达组成型活性Rac1 （RacET）的转基因小鼠出现年龄依赖性表型，伴有心房扩张、纤维化和心房颤动。MR在RacET和WT小鼠中的表达相似。11羟基类固醇脱氢酶2型（11- hsd2）在RacET小鼠心房和左心室的mRNA和蛋白水平呈年龄依赖性上调。抑制Rac1香叶酰化的他汀类药物治疗降低了11-HSD2的上调。人左心房心肌Rac1活性与11-HSD2表达呈正相关（r = 0.7169）。免疫沉淀显示Rac1结合的11-HSD2相对于Rac1在RacET小鼠中的表达增强，而他汀类药物治疗降低了Rac1的表达。基底和phorbol 12-肉豆酸13-乙酸酯（PMA）诱导的NADPH氧化酶活性均升高，且与11-HSD2表达呈正相关（r = 0.788和r = 0.843）。在培养的H9c2心肌细胞中，l-丁硫氨酸亚砜对Rac1的激活增加；NSC23766抑制Rac1可降低11-HSD2 mRNA和蛋白的表达。NSC23766可抑制醛固酮诱导的结缔组织生长因子（CTGF）上调。心肌细胞转染11-HSD2 siRNA可消除醛固酮诱导的CTGF上调。醛固酮刺激的MR核易位被11-HSD2抑制剂卡贝诺洛酮阻断。在心脏成纤维细胞中，NSC23766和螺内酯可以抑制醛固酮诱导的核磁共振易位。NSC23766抑制醛固酮诱导的心肌成纤维细胞增殖和迁移，抑制CTGF和纤维连接蛋白的上调。总之，Rac1 GTPase调节11-HSD2表达、MR激活和MR介导的促纤维化信号。
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 11 hydroxysteroid dehydrogenase type 2 (11-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 11-HSD2 up-regulation. Samples of human left atrial myocardium showed a positive correlation between Rac1 activity and 11-HSD2 expression (r = 0.7169). Immunoprecipitation showed enhanced Rac1-bound 11-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 11-HSD2 expression (r = 0.788 and r = 0.843, respectively). In cultured H9c2 cardiomyocytes, Rac1 activation with l-buthionine sulfoximine increased; Rac1 inhibition with NSC23766 decreased 11-HSD2 mRNA and protein expression. Connective tissue growth factor (CTGF) up-regulation induced by aldosterone was prevented with NSC23766. Cardiomyocyte transfection with 11-HSD2 siRNA abolished the aldosterone-induced CTGF up-regulation. Aldosterone-stimulated MR nuclear translocation was blocked by the 11-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 11-HSD2 expression, MR activation, and MR-mediated pro-fibrotic signaling.