Essential Role of the RIα Subunit of cAMP-Dependent Protein Kinase in Regulating Cardiac Contractility and Heart Failure Development.

Background: The heart expresses 2 main subtypes of cAMP-dependent protein kinase (PKA; type I and II) that differ in their regulatory subunits, RIα and RIIα. Embryonic lethality of RIα knockout mice limits the current understanding of type I PKA function in the myocardium. The objective of this study was to test the role of RIα in adult heart contractility and pathological remodeling.

[Cyclic nucleotide phosphodiesterases: therapeutic targets in cardiac hypertrophy and failure].

Cyclic nucleotide phosphodiesterases (PDEs) modulate neurohormonal regulation of cardiac function by degrading cAMP and cGMP. In cardiomyocytes, multiple isoforms of PDEs with different enzymatic properties and subcellular locally regulate cyclic nucleotide levels and associated cellular functions. This organisation is severely disrupted during hypertrophy and heart failure (HF), which may contribute to disease progression.

EPAC1 inhibition protects the heart from doxorubicin-induced toxicity.

Anthracyclines, such as doxorubicin (Dox), are widely used chemotherapeutic agents for the treatment of solid tumors and hematologic malignancies. However, they frequently induce cardiotoxicity leading to dilated cardiomyopathy and heart failure. This study sought to investigate the role of the exchange protein directly activated by cAMP (EPAC) in Dox-induced cardiotoxicity and the potential cardioprotective effects of EPAC inhibition.

Membranes prime the RapGEF EPAC1 to transduce cAMP signaling.

EPAC1, a cAMP-activated GEF for Rap GTPases, is a major transducer of cAMP signaling and a therapeutic target in cardiac diseases. The recent discovery that cAMP is compartmentalized in membrane-proximal nanodomains challenged the current model of EPAC1 activation in the cytosol. Here, we discover that anionic membranes are a major component of EPAC1 activation.

Phosphodiesterases type 2, 3 and 4 promote vascular tone in mesenteric arteries from rats with heart failure.

Phosphodiesterases (PDE) type 3 and 4 promote vasoconstriction by hydrolysing cAMP. In experimental heart failure (HF), PDE3 makes PDE4 redundant in aorta, but it is not known if this occurs in resistance vessels, such as mesenteric artery. As PDE2 is increased in the failing myocardium, its possible role in the vasculature also needs to be addressed.

Cyclic nucleotide phosphodiesterases as therapeutic targets in cardiac hypertrophy and heart failure.

Cyclic nucleotide phosphodiesterases (PDEs) modulate the neurohormonal regulation of cardiac function by degrading cAMP and cGMP. In cardiomyocytes, multiple PDE isozymes with different enzymatic properties and subcellular localization regulate local pools of cyclic nucleotides and specific functions. This organization is heavily perturbed during cardiac hypertrophy and heart failure (HF), which can contribute to disease progression.

Cyclic nucleotide signaling and pacemaker activity.

The sinoatrial node (SAN) is the natural pacemaker of the heart, producing the electrical impulse that initiates every heart beat. Its activity is tightly controlled by the autonomic nervous system, and by circulating and locally released factors. Neurohumoral regulation of heart rate plays a crucial role in the integration of vital functions and influences behavior and ability to respond to changing environmental conditions.

Cyclic GMP modulating drugs in cardiovascular diseases: mechanism-based network pharmacology.

Mechanism-based therapy centred on the molecular understanding of disease-causing pathways in a given patient is still the exception rather than the rule in medicine, even in cardiology. However, recent successful drug developments centred around the second messenger cyclic guanosine-3'-5'-monophosphate (cGMP), which is regulating a number of cardiovascular disease modulating pathways, are about to provide novel targets for such a personalized cardiovascular therapy. Whether cGMP breakdown is inhibited or cGMP synthesis is stimulated via guanylyl cyclases or their upstream regulators in different cardiovascular disease phenotypes, the outcomes seem to be so far uniformly protective.

Mapping genetic changes in the cAMP-signaling cascade in human atria.

Aim: To obtain a quantitative expression profile of the main genes involved in the cAMP-signaling cascade in human control atria and in different cardiac pathologies.

Methods And Results: Expression of 48 target genes playing a relevant role in the cAMP-signaling cascade was assessed by RT-qPCR. 113 samples were obtained from right atrial appendages (RAA) of patients in sinus rhythm (SR) with or without atrium dilation, paroxysmal atrial fibrillation (AF), persistent AF or heart failure (HF); and left atrial appendages (LAA) from patients in SR or with AF.

Selective changes in cytosolic β-adrenergic cAMP signals and L-type Calcium Channel regulation by Phosphodiesterases during cardiac hypertrophy.

Background In cardiomyocytes, phosphodiesterases (PDEs) type 3 and 4 are the predominant enzymes that degrade cAMP generated by β-adrenergic receptors (β-ARs), impacting notably the regulation of the L-type Ca current (I). Cardiac hypertrophy (CH) is accompanied by a reduction in PDE3 and PDE4, however, whether this affects the dynamic regulation of cytosolic cAMP and I is not known. Methods and Results CH was induced in rats by thoracic aortic banding over a time period of five weeks and was confirmed by anatomical measurements.

Fibroblast growth factor 23 decreases PDE4 expression in heart increasing the risk of cardiac arrhythmia; Klotho opposes these effects.

The concentration of fibroblast growth factor 23 (FGF23) rises progressively in renal failure (RF). High FGF23 concentrations have been consistently associated with adverse cardiovascular outcomes or death, in chronic kidney disease (CKD), heart failure or liver cirrhosis. We identified the mechanisms whereby high concentrations of FGF23 can increase the risk of death of cardiovascular origin.

Cardiac Overexpression of PDE4B Blunts β-Adrenergic Response and Maladaptive Remodeling in Heart Failure.

Background: The cyclic AMP (adenosine monophosphate; cAMP)-hydrolyzing protein PDE4B (phosphodiesterase 4B) is a key negative regulator of cardiac β-adrenergic receptor stimulation. PDE4B deficiency leads to abnormal Ca handling and PDE4B is decreased in pressure overload hypertrophy, suggesting that increasing PDE4B in the heart is beneficial in heart failure.

Methods: We measured PDE4B expression in human cardiac tissues and developed 2 transgenic mouse lines with cardiomyocyte-specific overexpression of PDE4B and an adeno-associated virus serotype 9 encoding PDE4B.

Ion channels as effectors of cyclic nucleotide pathways: Functional relevance for arterial tone regulation.

Numerous mediators and drugs regulate blood flow or arterial pressure by acting on vascular tone, involving cyclic nucleotide intracellular pathways. These signals lead to regulation of several cellular effectors, including ion channels that tune cell membrane potential, Ca influx and vascular tone. The characterization of these vasocontrictive or vasodilating mechanisms has grown in complexity due to i) the variety of ion channels that are expressed in both vascular endothelial and smooth muscle cells, ii) the heterogeneity of responses among the various vascular beds, and iii) the number of molecular mechanisms involved in cyclic nucleotide signalling in health and disease.

Synergic PDE3 and PDE4 control intracellular cAMP and cardiac excitation-contraction coupling in a porcine model.

Aims: Cyclic AMP phosphodiesterases (PDEs) are important modulators of the cardiac response to β-adrenergic receptor (β-AR) stimulation. PDE3 is classically considered as the major cardiac PDE in large mammals and human, while PDE4 is preponderant in rodents. However, it remains unclear whether PDE4 also plays a functional role in large mammals.

Imipramine as an alternative to formamide to detubulate rat ventricular cardiomyocytes.

New Findings: What is the central question of this study? Can imipramine, an antidepressant agent that is a cationic amphiphilic drug that interferes with the phosphatidylinositol 4,5-bisphosphate (PI(4,5)P ) interactions with proteins maintaining the tubular system, be validated as a new detubulating tool? What is the main finding and its importance? Imipramine was validated as a more efficient and less toxic detubulating agent of cardiomyocytes than formamide. New insights are provided on how PI(4,5)P is crucial to maintaining T-tubule attachment to the cell surface and on the cardiotoxic effects of imipramine overdoses.

Abstract: Cardiac T-tubules are membrane invaginations essential for excitation-contraction coupling (ECC).

PDE2 regulates membrane potential, respiration and permeability transition of rodent subsarcolemmal cardiac mitochondria.

Cyclic adenosine monophosphate (cAMP) production regulates certain aspects of mitochondria function in rodent cardiomyocytes, such as ATP production, oxygen consumption, calcium import and mitochondrial permeability transition (MPT), but how this cAMP pool is controlled is not well known. Here, expression, localization and activity of several cAMP-degrading enzymes, i.e.

Metabolic Inhibition Induces Transient Increase of L-type Ca Current in Human and Rat Cardiac Myocytes.

Metabolic inhibition is a common condition observed during ischemic heart disease and heart failure. It is usually accompanied by a reduction in L-type Ca channel (LTCC) activity. In this study, however, we show that metabolic inhibition results in a biphasic effect on LTCC current (I) in human and rat cardiac myocytes: an initial increase of I is observed in the early phase of metabolic inhibition which is followed by the more classical and strong inhibition.

Cyclic nucleotide signalling compartmentation by PDEs in cultured vascular smooth muscle cells.

Background And Purpose: Up-regulation of phosphodiesterases (PDEs) is associated with several vascular diseases, and better understanding of the roles of each PDE isoform in controlling subcellular pools of cyclic nucleotides in vascular cells is needed. We investigated the respective role of PDE1, PDE5, and PDE9 in controlling intracellular cAMP and/or cGMP concentrations ([cAMP] , [cGMP] ) in cultured rat aortic smooth muscle cells (RASMCs).

Experimental Approach: We used selective inhibitors of PDE1 (PF-04471141), PDE5 (sildenafil), and PDE9 (PF-04447943) to measure cAMP- and cGMP-PDE activities with a radioenzymatic assay, in RASMC extracts.

CSRP3 mediates polyphenols-induced cardioprotection in hypertension.

Berries contain bioactive polyphenols, whose capacity to prevent cardiovascular diseases has been established recently in animal models as well in human clinical trials. However, cellular processes and molecular targets of berries polyphenols remain to be identified. The capacity of a polyphenol-enriched diet (i.

Cardiac adenylyl cyclase overexpression precipitates and aggravates age-related myocardial dysfunction.

Aims: Increase of cardiac cAMP bioavailability and PKA activity through adenylyl-cyclase 8 (AC8) overexpression enhances contractile function in young transgenic mice (AC8TG). Ageing is associated with decline of cardiac contraction partly by the desensitization of β-adrenergic/cAMP signalling. Our objective was to evaluate cardiac cAMP signalling as age increases between 2 months and 12 months and to explore whether increasing the bioavailability of cAMP by overexpression of AC8 could prevent cardiac dysfunction related to age.

Progression of excitation-contraction coupling defects in doxorubicin cardiotoxicity.

Cardiac failure is a common complication in cancer survivors treated with anthracyclines. Here we followed up cardiac function and excitation-contraction (EC) coupling in an in vivo doxorubicin (Dox) treated mice model (iv, total dose of 10 mg/Kg divided once every three days). Cardiac function was evaluated by echocardiography at 2, 6 and 15 weeks after the last injection.