A PDE3A Promoter Polymorphism Regulates cAMP-Induced Transcriptional Activity in Failing Human Myocardium

Phosphodiesterase in heart and vessels: from physiology to diseases

Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides, including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Both cyclic nucleotides are critical secondary messengers in the neurohormonal regulation in the cardiovascular system. PDEs precisely control spatiotemporal subcellular distribution of cyclic nucleotides in a cell- and tissue-specific manner, playing critical roles in physiological responses to hormone stimulation in the heart and vessels. Dysregulation of PDEs has been linked to the development of several cardiovascular diseases, such as hypertension, aneurysm, atherosclerosis, arrhythmia, and heart failure. Targeting these enzymes has been proven effective in treating cardiovascular diseases and is an attractive and promising strategy for the development of new drugs. In this review, we discuss the current understanding of the complex regulation of PDE isoforms in cardiovascular function, highlighting the divergent and even opposing roles of PDE isoforms in different pathogenesis.

PDE3A and GSK3B as Atrial Fibrillation Susceptibility Genes in the Chinese Population via Bioinformatics and Genome-Wide Association Analysis

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia, with uncovered genetic etiology and pathogenesis. We aimed to screen out AF susceptibility genes with potential pathogenesis significance in the Chinese population. Methods: Differentially expressed genes (DEGs) were screened by the Limma package in three GEO data sets of atrial tissue. AF-related genes were identified by combination of DEGs and public GWAS susceptibility genes. Potential drug target genes were selected using the DrugBank, STITCH and TCMSP databases. Pathway enrichment analyses of AF-related genes were performed using the databases GO and KEGG databases. The pathway gene network was visualized by Cytoscape software to identify gene–gene interactions and hub genes. GWAS analysis of 110 cases of AF and 1201 controls was carried out through a genome-wide efficient mixed model in the Fangshan population to verify the results of bioinformatic analysis. Results: A total of 3173 DEGs were identified, 57 of which were found to be significantly associated with of AF in public GWAS results. A total of 75 AF-related genes were found to be potential therapeutic targets. Pathway enrichment analysis selected 79 significant pathways and classified them into 7 major pathway networks. A total of 35 hub genes were selected from the pathway networks. GWAS analysis identified 126 AF-associated loci. PDE3A and GSK3B were found to be overlapping genes between bioinformatic analysis and GWAS analysis. Conclusions: We screened out several pivotal genes and pathways involved in AF pathogenesis. Among them, PDE3A and GSK3B were significantly associated with the risk of AF in the Chinese population. Our study provided new insights into the mechanisms of action of AF.

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. Clinically, PDE inhibition has been considered a promising approach to compensate for the catecholamine desensitization that accompanies HF. Although PDE3 inhibitors, such as milrinone or enoximone, have been used clinically to improve systolic function and alleviate the symptoms of acute HF, their chronic use has proved to be detrimental. Other PDEs, such as PDE1, PDE2, PDE4, PDE5, PDE9 and PDE10, have emerged as new potential targets to treat HF, each having a unique role in local cyclic nucleotide signalling pathways. In this Review, we describe cAMP and cGMP signalling in cardiomyocytes and present the various PDE families expressed in the heart as well as their modifications in pathological cardiac hypertrophy and HF. We also appraise the evidence from preclinical models as well as clinical data pointing to the use of inhibitors or activators of specific PDEs that could have therapeutic potential in HF.

Levosimendan increases the phosphorylation state of phospholamban in the isolated human atrium

Levosimendan (up to 10 µM) given alone failed to increase force of contraction in isolated electrically stimulated (1 Hz) left atrial (LA) preparations from wild-type mice. Only in the additional presence of 0.1 µM rolipram, an inhibitor of the activity of phosphodiesterase IV, levosimendan increased force of contraction in LA and increased the phosphorylation state of phospholamban at amino acid serine 16. Levosimendan alone increased the beating rate in isolated spontaneously beating right atrial preparations from mice and this effect was potentiated by rolipram. The positive inotropic and the positive chronotropic effects of levosimendan in mouse atrial preparations were attenuated by 10 µM propranolol. Finally, we studied the contractile effects of levosimendan in isolated electrically stimulated (1 Hz) right atrial preparations from the human atrium (HAP), obtained during cardiac surgery. We detected concentration-dependent positive inotropic effects of levosimendan alone that reached plateau at 1 µM levosimendan in HAP (n = 11). Levosimendan shortened time of tension relaxation in HAP. Cilostamide (1 µM), an inhibitor of phosphodiesterase III, or propranolol (10 µM) blocked the positive inotropic effect of levosimendan in HAP. Levosimendan (1 µM) alone increased in HAP the phosphorylation state of phospholamban. In conclusion, we present evidence that levosimendan acts via phosphodiesterase III inhibition in the human atrium leading to phospholamban phosphorylation and thus explaining the positive inotropic effects of levosimendan in HAP.

A Mutation in Endogenous saRNA miR-23a Influences Granulosa Cells Response to Oxidative Stress

Phenotypes are the result of the interaction between the gene and the environment, so the response of individuals with different genotypes to an environment is variable. Here, we reported that a mutation in miR-23a influences granulosa cells (GCs) response to oxidative stress, a common mechanism of environmental factors affecting female reproduction. We showed that nuclear miR-23a is a pro-apoptotic miRNA in porcine GCs through the activation of the transcription and function of NORHA, a long non-coding RNA (lncRNA) induces GC apoptosis and responses to oxidative stress. Mechanistically, miR-23a acts as an endogenous small activating RNA (saRNA) to alter histone modifications of the NORHA promoter through the direct binding to its core promoter. A C > T mutation was identified at −398 nt of the miR-23a core promoter, which created a novel binding site for the transcription factor SMAD4 and recruited the transcription repressor SMAD4 to inhibit miR-23a transcription and function in GCs. Notably, g.−398C > T mutation in the miR-23a promoter reduced GCs response to oxidative stress. In addition, g.−398C > T mutation was significantly associated with sow fertility traits. In short, our findings preliminarily revealed the genetic basis of individual differences in the response to oxidative stress from the perspective of a single mutation and identified miR-23a as a candidate gene for the environmental adaptation to oxidative stress.

Medical Therapies for Heart Failure in Hypoplastic Left Heart Syndrome

Significant surgical and medical advances over the past several decades have resulted in a growing number of infants and children surviving with hypoplastic left heart syndrome (HLHS) and other congenital heart defects associated with a single systemic right ventricle (RV). However, cardiac dysfunction and ultimately heart failure (HF) remain the most common cause of death and indication for transplantation in this population. Moreover, while early recognition and treatment of single ventricle-related complications are essential to improving outcomes, there are no proven therapeutic strategies for single systemic RV HF in the pediatric population. Importantly, prototypical adult HF therapies have been relatively ineffective in mitigating the need for cardiac transplantation in HLHS, likely due to several unique attributes of the failing HLHS myocardium. Here, we discuss the most commonly used medical therapies for the treatment of HF symptoms in HLHS and other single systemic RV patients. Additionally, we provide an overview of potential novel therapies for systemic ventricular failure in the HLHS and related populations based on fundamental science, pre-clinical, clinical, and observational studies in the current literature.

Role of lncSLCO1C1 in gastric cancer progression and resistance to oxaliplatin therapy

BACKGROUND

Gastric carcinoma (GC) is one of the most deadly diseases due to tumour metastasis and resistance to therapy. Understanding the molecular mechanism of tumour progression and drug resistance will improve therapeutic efficacy and develop novel intervention strategies.

METHODS

Differentially expressed long non-coding RNAs (lncRNAs) in clinical specimens were identified by LncRNA microarrays and validated in different clinical cohorts by quantitative real-time polymerase chain reaction (qRT-PCR), in situ hybridisation and bioinformatics analysis. Biological functions of lncRNA were investigated by using cell proliferation assays, migration assays, xenograft tumour models and bioinformatics analysis. Effects of lncSLCO1C1 on GC cell survival were assessed by comet assays and immunofluorescence assays. Underlying molecular mechanisms were further explored by using a number of technologies including RNA pull-down, mass spectrometry analysis, RNA immunoprecipitation, co-immunoprecipitation, miRNA sequencing, luciferase reporter assays and molecular modelling.

RESULTS

LncSLCO1C1 was highly upregulated in GC tissue samples and associated with GC patients' poor overall survival. Overexpression of lncSLCO1C1 promoted proliferation and migration, whereas decreased lncSLCO1C1 expression produced the opposite effects. lncSLCO1C1 also mediated tumour resistance to chemotherapy with oxaliplatin by reducing DNA damage and increasing cell proliferation. Despite sequence overlapping between lncSLCO1C1 and PDE3A, alternations of PDE3A expression had no effect on the GC cell progression, indicating that lncSLCO1C1, not PDE3A, related with the progression of GC cells. Mechanistically, lncSLCO1C1 serves as a scaffold for the structure-specific recognition protein 1 (SSRP1)/H2A/H2B complex and regulates the function of SSRP1 in reducing DNA damage. Meanwhile, lncSLCO1C1 functions as a sponge to adsorb miR-204-5p and miR-211-5p that target SSRP1 mRNA, and thus increases SSRP1 expression. Patients with high expressions of both lncSLCO1C1 and SSRP1 have poor overall survival, highlighting the role of lncSLCO1C1 in GC progression.

CONCLUSIONS

LncSLCO1C1 promotes GC progression by enhancing cell growth and preventing DNA damage via interacting and scaffolding the SSRP1/H2A/H2b complex and absorbing both miR-211-5p and miR-204-5p to increase SSRP1 expression.

Potassium Alginate Oligosaccharides Alter Gut Microbiota, and Have Potential to Prevent the Development of Hypertension and Heart Failure in Spontaneously Hypertensive Rats

Food-derived oligosaccharides show promising therapeutic potential in lowering blood pressure (BP), but the mechanism is poorly understood. Recently, the potential role of gut microbiota (GM) in hypertension has been investigated, but the specific GM signature that may participate in hypertension remains unclear. To test the potassium alginate oligosaccharides (PAO) mechanism in lowering BP and specific microbial signature changes in altering GM, we administered various dosages of PAO in 40 spontaneously hypertensive rats for a duration of six weeks. We analyzed BP, sequenced the 16S ribosomal DNA gene in the cecum content, and gathered RNA-seq data in cardiac tissues. We showed that the oral administration of PAO could significantly decrease systolic BP and mean arterial pressure. Transcriptome analyses demonstrated that the protective effects of developing heart failure were accompanied by down-regulating of the Natriuretic Peptide A gene expression and by decreasing the concentrations of angiotensin II and atrial natriuretic peptide in plasma. In comparison to the Vehicle control, PAO could increase the microbial diversity by altering the composition of GM. PAO could also decrease the ratio of Firmicutes to Bacteroidetes by decreasing the abundance of Prevotella and Phascolarctobacterium bacteria. The favorable effect of PAO may be added to the positive influence of the abundance of major metabolites produced by Gram-negative bacteria in GM. We suggest that PAO caused changes in GM, and thus, they played an important role in preventing the development of cardiovascular disease.

Circulating cyclic adenosine monophosphate concentrations in milrinone treated paediatric patients after congenital heart surgery

BACKGROUND

Milrinone is a phosphodiesterase type 3 inhibitor that results in a positive inotropic effect in the heart through an increase in cyclic adenosine monophosphate. The purpose of this study was to evaluate circulating cyclic adenosine monophosphate and milrinone concentrations in milrinone treated paediatric patients undergoing congenital heart surgery.

METHODS

Single-centre prospective observational pilot study from January 2015 to December 2017 including children aged birth to 18 years. Milrinone and circulating cyclic adenosine monophosphate concentrations were measured at four time points through the first post-operative day and compared between patients with and without low cardiac output syndrome, defined using clinical and laboratory criteria.

RESULTS

Fifty patients were included. Nine (18%) developed low cardiac output syndrome. For all patients, 22% had single ventricle heart disease. The density and distribution of cyclic adenosine monophosphate concentrations varied between those with and without low cardiac output syndrome but were not significantly different. Milrinone concentrations increased in all patients. Paired t-tests demonstrated an increase in circulating cyclic adenosine monophosphate concentrations during the post-operative period among patients without low cardiac output syndrome.

CONCLUSIONS

In this prospective observational study, circulating cyclic adenosine monophosphate concentrations increased in those without low cardiac output syndrome during the first 24 post-operative hours and milrinone concentrations increased in all patients. Further study of the utility of cyclic adenosine monophosphate concentrations in milrinone treated patients is necessary.

Myocardial Phosphodiesterases and Their Role in cGMP Regulation

Cyclic nucleotide phosphodiesterases comprise an 11-member superfamily yielding near 100 isoform variants that hydrolyze cAMP or cGMP to their respective 5'-monophosphate form. Each plays a role in compartmentalized cyclic nucleotide signaling, with varying selectivity for each substrate, and conveying cell and intracellular-specific localized control. This review focuses on the 5 phosphodiesterases (PDEs) expressed in the cardiac myocyte capable of hydrolyzing cGMP and that have been shown to play a role in cardiac physiological and pathological processes. PDE1, PDE2, and PDE3 catabolize cAMP as well, whereas PDE5 and PDE9 are cGMP selective. PDE3 and PDE5 are already in clinical use, the former for heart failure, and PDE1, PDE9, and PDE5 are all being actively studied for this indication in patients. Research in just the past few years has revealed many novel cardiac influences of each isoform, expanding the therapeutic potential from their selective pharmacological blockade or in some instances, activation. PDE1C inhibition was found to confer cell survival protection and enhance cardiac contractility, whereas PDE2 inhibition or activation induces beneficial effects in hypertrophied or failing hearts, respectively. PDE3 inhibition is already clinically used to treat acute decompensated heart failure, although toxicity has precluded its long-term use. However, newer approaches including isoform-specific allosteric modulation may change this. Finally, inhibition of PDE5A and PDE9A counter pathological remodeling of the heart and are both being pursued in clinical trials. Here, we discuss recent research advances in each of these PDEs, their impact on the myocardium, and cardiac therapeutic potential.

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 Ca2+ current (ICa,L). Cardiac hypertrophy (CH) is accompanied by a reduction in PDE3 and PDE4, however, whether this affects the dynamic regulation of cytosolic cAMP and ICa,L 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. Left ventricular myocytes (LVMs) were isolated from CH and sham-operated (SHAM) rats and transduced with an adenovirus encoding a Förster resonance energy transfer (FRET)-based cAMP biosensor or subjected to the whole-cell configuration of the patch-clamp technique to measure ICa,L. Aortic stenosis resulted in a 46% increase in heart weight to body weight ratio in CH compared to SHAM. In SHAM and CH LVMs, a short isoprenaline stimulation (Iso, 100 nM, 15 s) elicited a similar transient increase in cAMP with a half decay time (t1/2off) of ~50 s. In both groups, PDE4 inhibition with Ro 20-1724 (10 μM) markedly potentiated the amplitude and slowed the decline of the cAMP transient, this latter effect being more pronounced in SHAM (t1/2off ~ 250 s) than in CH (t1/2off ~ 150 s, P < 0.01). In contrast, PDE3 inhibition with cilostamide (1 μM) had no effect on the amplitude of the cAMP transient and a minimal effect on its recovery in SHAM, whereas it potentiated the amplitude and slowed the decay in CH (t1/2off ~ 80 s). Iso pulse stimulation also elicited a similar transient increase in ICa,L in SHAM and CH, although the duration of the rising phase was delayed in CH. Inhibition of PDE3 or PDE4 potentiated ICa,L amplitude in SHAM but not in CH. Besides, while only PDE4 inhibition slowed down the decline of ICa,L in SHAM, both PDE3 and PDE4 contributed in CH. Conclusion These results identify selective alterations in cytosolic cAMP and ICa,L regulation by PDE3 and PDE4 in CH, and show that the balance between PDE3 and PDE4 for the regulation of β-AR responses is shifted toward PDE3 during CH.

Identification and functional study of genetic polymorphisms in cyclic nucleotide phosphodiesterase 3A (PDE3A)

Phosphodiesterase 3A (PDE3A) is an enzyme that plays an important role in the regulation of cyclic adenosine monophosphate (cAMP)-mediated intracellular signaling in cardiac myocytes and platelets. PDE3A hydrolyzes cAMP, which results in a decrease in intracellular cAMP levels and leads to platelet activation. Whole-exome sequencing of 50 DNA samples from a healthy Korean population revealed a total of 13 single nucleotide polymorphisms including five missense variants, D12N, Y497C, H504Q, C707R, and A980V. Recombinant proteins for the five variants of PDE3A (and wild-type protein) were expressed in a FreeStyle 293 expression system with site-directed mutagenesis. The expression of the recombinant PDE3A proteins was confirmed with Western blotting. Catalytic activity of the PDE3A missense variants and wild-type enzyme was measured with a PDE-based assay. Effects of the missense variants on the inhibition of PDE3A activity by cilostazol were also investigated. All variant proteins showed reduced activity (33-53%; p < .0001) compared to the wild-type protein. In addition, PDE3A activity was inhibited by cilostazol in a dose-dependent manner and was further suppressed in the missense variants. Specifically, the PDE3A Y497C showed significantly reduced activity, consistent with the predictions of in silico analyses. The present study provides evidence that individuals carrying the PDE3A Y497C variant may have lower enzyme activity for cAMP hydrolysis, which could cause interindividual variation in cAMP-mediated physiological functions.

To Explore the Mechanism and Equivalent Molecular Group of Fuxin Mixture in Treating Heart Failure Based on Network Pharmacology

Fuxin mixture (FXHJ) is a prescription for the treatment of heart failure. It has been shown to be effective in clinical trials, but its active ingredients and mechanism of action are not completely clear, which limits its clinical application and international promotion. In this study, we used network pharmacology to find, conclude, and summarize the mechanism of FXHJ in the treatment of heart failure. From FXHJ, we found 39 active ingredients and 47 action targets. Next, we constructed the action network and was conducted enrichment analysis. The results showed that FXHJ mainly treated heart failure by regulating the MAPK signaling pathway, PI3KAkt signaling pathway, cAMP signaling pathway, TNF signaling pathway, toll-like receptor signaling pathway, VEGF signaling pathway, NF-kappa B signaling pathway, and the apoptotic signaling molecule BCL2. Through the research method of network pharmacology, this study summarized the preliminary experiments of the research group and revealed the probable mechanism of FXHJ in the treatment of heart failure to a certain extent, which provided some ideas for the development of new drugs.

Cardiac Cyclic Nucleotide Phosphodiesterases: Roles and Therapeutic Potential in Heart Failure

The cyclic nucleotides cyclic adenosine-3′,5′-monophosphate (cAMP) and cyclic guanosine-3′,5′-monophosphate (cGMP) maintain physiological cardiac contractility and integrity. Cyclic nucleotide–hydrolysing phosphodiesterases (PDEs) are the prime regulators of cAMP and cGMP signalling in the heart. During heart failure (HF), the expression and activity of multiple PDEs are altered, which disrupt cyclic nucleotide levels and promote cardiac dysfunction. Given that the morbidity and mortality associated with HF are extremely high, novel therapies are urgently needed. Herein, the role of PDEs in HF pathophysiology and their therapeutic potential is reviewed. Attention is given to PDEs 1–5, and other PDEs are briefly considered. After assessing the role of each PDE in cardiac physiology, the evidence from pre-clinical models and patients that altered PDE signalling contributes to the HF phenotype is examined. The potential of pharmacologically harnessing PDEs for therapeutic gain is considered.

Heart failure in single right ventricle congenital heart disease: physiological and molecular considerations

Because of remarkable surgical and medical advances over the past several decades, there are growing numbers of infants and children living with single ventricle congenital heart disease (SV), where there is only one functional cardiac pumping chamber. Nevertheless, cardiac dysfunction (and ultimately heart failure) is a common complication in the SV population, and pharmacological heart failure therapies have largely been ineffective in mitigating the need for heart transplantation. Given that there are several inherent risk factors for ventricular dysfunction in the setting of SV in addition to probable differences in molecular adaptations to heart failure between children and adults, it is perhaps not surprising that extrapolated adult heart failure medications have had limited benefit in children with SV heart failure. Further investigations into the molecular mechanisms involved in pediatric SV heart failure may assist with risk stratification as well as development of targeted, efficacious therapies specific to this patient population. In this review, we present a brief overview of SV anatomy and physiology, with a focus on patients with a single morphological right ventricle requiring staged surgical palliation. Additionally, we discuss outcomes in the current era, risk factors associated with the progression to heart failure, present state of knowledge regarding molecular alterations in end-stage SV heart failure, and current therapeutic interventions. Potential avenues for improving SV outcomes, including identification of biomarkers of heart failure progression, implications of personalized medicine and stem cell-derived therapies, and applications of novel models of SV disease, are proposed as future directions.