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Abstract: Cardiac remodeling (cardiac hypertrophy and fibrosis) is a hallmark of heart failure (HF). It can be induced by the abnormal elevation of several endogenous factors including angiotensin II (Ang II), which is generated from its precursor angiotensin I (Ang I) by the action of angiotensin‐converting enzyme. The inhibition of this enzyme or the blockade of the Ang II receptors demonstrated a high clinical value against the progression of HF. Ang I and Ang II may also be converted into angiotensin 1‐7 (Ang 1‐7) and angiotensin 1‐9 (Ang 1‐9), respectively, by the action of angiotensin‐converting enzyme 2. Both derivatives demonstrated a promising anticardiac remodeling activity especially against the detrimental effects of Ang II. This manuscript thoroughly reviews the available in vitro and in vivo data on Ang 1‐7 and Ang 1‐9 in the context of the treatment of HF and discusses the associated molecular mechanisms and the trials to clinically utilize Ang 1‐7 mimetics for the treatment of that disease. [ABSTRACT FROM AUTHOR]

Introduction: RhoA has been shown to be beneficial in cardiac disease models when overexpressed in cardiomyocytes, whereas its role in cardiac fibroblasts (CF) is still poorly understood. During cardiac remodeling CF undergo a transition towards a myofibroblast phenotype thereby showing an increased proliferation and migration rate. Both processes involve the remodeling of the cytoskeleton. Since RhoA is known to be a major regulator of the cytoskeleton, we analyzed its role in CF and its effect on myofibroblast characteristics in 2 D and 3D models. Results: Downregulation of RhoA was shown to strongly affect the actin cytoskeleton. It decreased the myofibroblast marker α-sm-actin, but increased certain fibrosis-associated factors like TGF-β and collagens. Also, the detailed analysis of CTGF expression demonstrated that the outcome of RhoA signaling strongly depends on the involved stimulus. Furthermore, we show that proliferation of myofibroblasts rely on RhoA and tubulin acetylation. In assays accessing three different types of migration, we demonstrate that RhoA/ROCK/Dia1 are important for 2D migration and the repression of RhoA and Dia1 signaling accelerates 3D migration. Finally, we show that a downregulation of RhoA in CF impacts the viscoelastic and contractile properties of engineered tissues. Conclusion: RhoA positively and negatively influences myofibroblast characteristics by differential signaling cascades and depending on environmental conditions. These include gene expression, migration and proliferation. Reduction of RhoA leads to an increased viscoelasticity and a decrease in contractile force in engineered cardiac tissue. [ABSTRACT FROM AUTHOR]