Rationale 3′-5′-cyclic adenosine monophosphate (cAMP) and 3′-5′-cyclic guanosine monophosphate (cGMP) are intracellular second messengers involved in heart pathophysiology. cGMP can potentially affect cAMP signals via cGMP-regulated phosphodiesterases (PDEs). Objective To study the effect of cGMP signals on the local cAMP response to catecholamines in specific subcellular compartments. Methods and results We used real-time FRET imaging of living rat ventriculocytes expressing targeted cAMP and cGMP biosensors to detect cyclic nucleotides levels in specific locales. We found that the compartmentalized, but not the global, cAMP response to isoproterenol is profoundly affected by cGMP signals. The effect of cGMP is to increase cAMP levels in the compartment where the PKA-RI isoforms reside but to decrease cAMP in the compartment where the PKA-RII isoforms reside. These opposing effects are determined by the cGMP-regulated PDEs, namely PDE2 and PDE3, with the local activity of these PDEs being critically important. The cGMP-mediated modulation of cAMP also affects the phosphorylation of PKA targets and myocyte contractility. Conclusions cGMP signals exert opposing effects on local cAMP levels via different PDEs the activity of which is exerted in spatially distinct subcellular domains. Inhibition of PDE2 selectively abolishes the negative effects of cGMP on cAMP and may have therapeutic potential.
Objective-To develop an embryoid body-free directed differentiation protocol for the rapid generation of functional vascular endothelial cells derived from human embryonic stem cells (hESCs) and to assess the system for microRNA regulation and angiogenesis. Methods and Results-The production of defined cell lineages from hESCs is a critical requirement for evaluating their potential in regenerative medicine. We developed a feeder-and serum-free protocol. Directed endothelial differentiation of hESCs revealed rapid loss of pluripotency markers and progressive induction of mRNA and protein expression of vascular markers (including CD31 and vascular endothelial [VE]-cadherin) and angiogenic growth factors (including vascular endothelial growth factor), increased expression of angiogenesis-associated microRNAs (including miR-126 and miR-210), and induction of endothelial cell morphological features. In vitro, differentiated cells produced nitric oxide, migrated across a wound, and formed tubular structures in both the absence and the presence of 3D matrices (Matrigel). In vivo, we showed that cells that differentiated for 10 days before implantation were efficient at the induction of therapeutic neovascularization and that hESC-derived cells were incorporated into the blood-perfused vasculature of recipient mice. Conclusion-The
Abstract-Angiotensin-converting enzyme (ACE) 2 is a recently identified homologue of ACE. There is great interest in the therapeutic benefit for ACE2 overexpression in the heart. However, the role of ACE2 in the regulation of cardiac structure and function, as well as maintenance of systemic blood pressure, remains poorly understood. In cell culture, ACE2 overexpression led to markedly increased myocyte volume, assessed in primary rabbit myocytes. To assess ACE2 function in vivo, we used a recombinant adeno-associated virus 6 delivery system to provide 11-week overexpression of ACE2 in the myocardium of stroke-prone spontaneously hypertensive rats. ACE2, as well as the ACE inhibitor enalapril, significantly reduced systolic blood pressure. However, in the heart, ACE2 overexpression resulted in cardiac fibrosis, as assessed by histological analysis with concomitant deficits in ejection fraction and fractional shortening measured by echocardiography. Furthermore, global gene expression profiling demonstrated the activation of profibrotic pathways in the heart mediated by ACE2 gene delivery. This study demonstrates that sustained overexpression of ACE2 in the heart in vivo leads to the onset of severe fibrosis. (Hypertension. 2009;53:694-700.)Key Words: ACE2 Ⅲ gene delivery Ⅲ adeno-associated virus Ⅲ hypertension Ⅲ myocardium O veractivity of the renin-angiotensin (Ang) system plays a fundamental role in the pathophysiology of hypertension and progression of heart failure. 1 Ang-converting enzyme (ACE) 2 is a recently identified homologue of ACE, and their catalytic domains share 42% amino acid identity. 2-4 ACE2 expression is restricted to the heart, kidney, and testis. 2,5 After myocardial infarction, increased ACE2 expression in the heart localized to vascular endothelium, smooth muscle, and cardiomyocytes in both rats and humans. 6 Unlike ACE, ACE2 functions as a carboxypeptidase rather than a dipeptidyl carboxypeptidase 5 and counterbalances the vasopressor effects of ACE. 7 ACE2 primarily hydrolyzes Ang II and, less efficiently, Ang I, 2 resulting in Ang 1-7 and Ang 1-9. Ang 1-9 is further hydrolyzed to Ang 1-7 by the actions of ACE. 5 ACE inhibitors and Ang II receptor blockers are effective drugs for the treatment of cardiovascular diseases, as a result of blocking the vasoconstrictor, hypertrophic, and proinflammatory actions of Ang II. 8 -11 Thus, ACE2 may play a pivotal role in the renin-Ang system by reducing concentrations of Ang II and raising levels of Ang 1-7. 12,13 Therefore, manipulation of ACE2 activity has potential therapeutic use. However, ACE2 knockout mice have been associated with severe contractile dysfunction 14 or, conversely, with no observed effects on cardiac dimension or function. 15 Overexpression of ACE2 by local delivery of lentivirus in the hearts of spontaneously hypertensive rats attenuated high blood pressure (BP) and perivascular fibrosis, reduced left ventricular (LV) wall thickness, and increased LV end diastolic and end systolic diameters. 16 Conversely, transgenic overex...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.