Phosphodiesterase4D (PDE4D)--A risk factor for atrial fibrillation and stroke?

Circulating long noncoding RNA PDE4DIPP6: A novel biomarker for improving the clinical management of non-ST-segment elevation myocardial infarction

BACKGROUND

Long noncoding RNAs (lncRNAs) have emerged as promising diagnostic biomarkers. Here, we investigated the cardiac-expressed and plasma-detectable lncRNA PDE4DIPP6 as a biomarker for non-ST-segment elevation myocardial infarction (NSTEMI), specifically assessing its potential to enhance the diagnostic efficacy of high-sensitivity cardiac troponin (hs-cTnT).

METHODS AND RESULTS

The study enrolled individuals presenting with suspected acute coronary syndrome (ACS). LncRNA quantification was performed in plasma samples using RT-qPCR. The discriminatory performance was assessed by calculating the Area Under the Curve (AUC). Reclassification metrics, including the Integrated Discrimination Improvement (IDI) and Net Reclassification Improvement (NRI) indexes, were utilized to evaluate enhancements in diagnostic accuracy. Among the 252 patients with suspected ACS, 50.8 % were diagnosed with ACS, and 13.9 % with NSTEMI. Initially, the association of lncRNA PDE4DIPP6 with ACS was investigated. Elevated levels of this lncRNA were observed in ACS patients compared to non-ACS subjects. No association was found between lncRNA PDE4DIPP6 levels and potential confounding factors, nor was a significant correlation with hs-cTnT levels (rho = 0.071). The inclusion of lncRNA PDE4DIPP6 on top of hs-cTnT significantly improved the discrimination and classification of ACS patients, as reflected by an enhanced AUC of 0.734, an IDI of 0.066 and NRI of 0.471. Subsequently, the lncRNA PDE4DIPP6 was evaluated as biomarker of NSTEMI. Elevated levels of the lncRNA were observed in NSTEMI patients compared to patients without NSTEMI. Consistent with previous findings, the addition of lncRNA PDE4DIPP6 to hs-cTnT improved the discrimination and classification of patients, increasing the AUC from 0.859 to 0.944, with an IDI of 0.237 and NRI of 0.658.

CONCLUSION

LncRNA PDE4DIPP6 offers additional diagnostic insights beyond hs-cTnT, suggesting its potential to improve the clinical management of patients with NSTEMI.

Runx1 promotes neuronal injury in ischemic stroke through mediating miR-203-3p/Pde4d axis

BACKGROUND

It has been reported that Runx1 engaged in IS progression, but the detailed mechanism of Runx1 in IS is still unclear.

METHODS

Mice and HT22 cells were subjected to the process of middle cerebral artery occlusion and reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation (OGD/R), respectively. Infract volume was tested using TTC staining. The levels of inflammatory cytokines were investigated using ELISA assay. Cell viability was examined utilizing MTS. Apoptosis rate was evaluated using flow cytometry and TUNEL. The productions of SOD and MDA were monitored by means of commercial kits. The correlations among Runx1, miR-203-3p and Pde4d were ascertained using dual luciferase reporter gene, ChIP and RNA-RNA pull-down assays.

RESULTS

Runx1 and Pde4d were abnormally elevated, while miR-203-3p was notably declined in MCAO/R mice and OGD/R-induced HT22 cells. OGD/R treatment suppressed cell viability and facilitated cell apoptosis, inflammation and oxidative stress, which were compromised by Runx1 knockdown or miR-203-3p upregulation. Runx1 bound to miR-203-3p promoter, thus decreasing miR-203-3p expression. MiR-203-3p inhibited Pde4d expression via targeting Pde4d mRNA. Runx1 deficiency-induced protection effects on OGD/R-treated HT22 cells were offset by miR-203-3p downregulation.

CONCLUSION

Runx1 aggravated neuronal injury caused by IS through mediating miR-203-3p/Pde4d axis.

Whole-exome sequencing analyses in a Saudi Ischemic Stroke Cohort reveal association signals, and shows polygenic risk scores are related to Modified Rankin Scale Risk

Ischemic stroke represents a significant societal burden across the globe. Rare high penetrant monogenic variants and less pathogenic common single nucleotide polymorphisms (SNPs) have been described as being associated with risk of diseases. Genetic studies in Saudi Arabian patients offer a greater opportunity to detect rare high penetrant mutations enriched in these consanguineous populations. We performed whole exome sequencing on 387 ischemic stroke subjects from Saudi Arabian hospital networks with up to 20,230 controls from the Saudi Human Genome Project and performed gene burden analyses of variants in 177 a priori loci derived from knowledge-driven curation of monogenic and genome-wide association studies of stroke. Using gene-burden analyses, we observed significant associations in numerous loci under autosomal dominant and/or recessive modelling. Stroke subjects with modified Rankin Scale (mRSs) above 3 were found to carry greater cumulative polygenic risk score (PRS) from rare variants in stroke genes (standardized PRS mean > 0) compared to the population average (standardized PRS mean = 0). However, patients with mRS of 3 or lower had lower cumulative genetic risk from rare variants in stroke genes (OR (95%CI) = 1.79 (1.29-2.49), p = 0.0005), with the means of standardized PRS at or lower than 0. In conclusion, gene burden testing in Saudi stroke populations reveals a number of statistically significant signals under different disease inheritance models. However, interestingly, stroke subjects with mRS of 3 or lower had lower cumulative genetic risk from rare variants in stroke genes and therefore, determining the potential mRS cutoffs to use for clinical significance may allow risk stratification of this population.

Tracking footprints of artificial and natural selection signatures in breeding and non-breeding cats

Stray non-breeding cats (stray) represent the largest heterogeneous cat population subject to natural selection, while populations of the Siamese (SIAM) and Oriental Shorthair (OSH) breeds developed through intensive artificial selection for aesthetic traits. Runs of homozygosity (ROH) and demographic measures are useful tools to discover chromosomal regions of recent selection and to characterize genetic diversity in domestic cat populations. To achieve this, we genotyped 150 stray and 26 household non-breeding cats (household) on the Illumina feline 63 K SNP BeadChip and compared them to SIAM and OSH. The 50% decay value of squared correlation coefficients (r²) in stray (0.23), household (0.25), OSH (0.24) and SIAM (0.25) corresponded to a mean marker distance of 1.12 Kb, 4.55 Kb, 62.50 Kb and 175.07 Kb, respectively. The effective population size (N_e) decreased in the current generation to 55 in stray, 11 in household, 9 in OSH and 7 in SIAM. In the recent generation, the increase in inbreeding per generation (ΔF) reached its maximum values of 0.0090, 0.0443, 0.0561 and 0.0710 in stray, household, OSH and SIAM, respectively. The genomic inbreeding coefficient (F_ROH) based on ROH was calculated for three length categories. The F_ROH was between 0.014 (F_ROH60) and 0.020 (F_ROH5) for stray, between 0.018 (F_ROH60) and 0.024 (F_ROH5) for household, between 0.048 (F_ROH60) and 0.069 (F_ROH5) for OSH and between 0.053 (F_ROH60) and 0.073 (F_ROH5) for SIAM. We identified nine unique selective regions for stray through genome-wide analyses for regions with reduced heterozygosity based on F_ST statistics. Genes in these regions have previously been associated with reproduction (BUB1B), motor/neurological behavior (GPHN, GABRB3), cold-induced thermogenesis (DIO2, TSHR), immune system development (TSHR), viral carcinogenesis (GTF2A1), host immune response against bacteria, viruses, chemoattractant and cancer cells (PLCB2, BAHD1, TIGAR), and lifespan and aging (BUB1B, FGF23). In addition, we identified twelve unique selective regions for OSH containing candidate genes for a wide range of coat colors and patterns (ADAMTS20, KITLG, TYR, TYRO3-a MITF regulator, GPNMB, FGF7, RAB38) as well as congenital heart defects (PDE4D, PKP2) and gastrointestinal disorders (NLGN1, ALDH1B1). Genes in stray that represent unique selective events indicate, at least in part, natural selection for environmental adaptation and resistance to infectious disease, and should be the subject of future research. Stray cats represent an important genetic resource and have the potential to become a research model for disease resistance and longevity, which is why we recommend preserving semen before neutering.

Phosphodiesterase type 4 anchoring regulates cAMP signaling to Popeye domain-containing proteins

Cyclic AMP is a ubiquitous second messenger used to transduce intracellular signals from a variety of Gs-coupled receptors. Compartmentalisation of protein intermediates within the cAMP signaling pathway underpins receptor-specific responses. The cAMP effector proteins protein-kinase A and EPAC are found in complexes that also contain phosphodiesterases whose presence ensures a coordinated cellular response to receptor activation events. Popeye domain containing (POPDC) proteins are the most recent class of cAMP effectors to be identified and have crucial roles in cardiac pacemaking and conduction. We report the first observation that POPDC proteins exist in complexes with members of the PDE4 family in cardiac myocytes. We show that POPDC1 preferentially binds the PDE4A sub-family via a specificity motif in the PDE4 UCR1 region and that PDE4s bind to the Popeye domain of POPDC1 in a region known to be susceptible to a mutation that causes human disease. Using a cell-permeable disruptor peptide that displaces the POPDC1-PDE4 complex we show that PDE4 activity localized to POPDC1 modulates cycle length of spontaneous Ca²⁺ transients firing in intact mouse sinoatrial nodes.

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POPDC1 forms a complex with type 4 phosphodiesterases (PDE4s) in cardiac myocytes.

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POPDC1 binds PDE4 enzymes in the Upstream Conserved Region 1 (UCR1) domain.

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The PDE4 binding motif within the Popeye domain lies in a region that harbours a mutation, which underpins human disease.

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Disruption of the POPDC1-PDE4 complex modulates the cycle length of spontaneous Ca2+ transients in the sinoatrial node.

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Disruption of the POPDC1-PDE4 complex causes a significant prolongation of the action potential repolarization phase.

Epistatic interaction of PDE4DIP and DES mutations in familial atrial fibrillation with slow conduction

The genetic causes of atrial fibrillation (AF) with slow conduction are unknown. Eight kindreds with familial AF and slow conduction, including a family affected by early-onset AF, heart block, and incompletely penetrant nonischemic dilated cardiomyopathy (DCM) underwent whole exome sequencing. A known pathogenic mutation in the desmin (DES) gene resulting in p.S13F substitution (NM_001927.3:c.38C>T) at a PKC phosphorylation site was identified in all four members of the kindred with early-onset AF and heart block, while only two developed DCM. Higher penetrance for AF and heart block prompted a genetic screening for DES modifier(s). A deleterious mutation in the phosphodiesterase-4D-interacting-protein (PDE4DIP) gene resulting in p.A123T substitution (NM_001002811:c.367G>A) was identified that segregated with early-onset AF, heart block, and the DES mutation. Three additional novel deleterious PDE4DIP mutations were identified in four other unrelated kindreds. Characterization of PDE4DIP^A123T in vitro suggested impaired compartmentalization of PKA and PDE4D characterized by reduced colocalization with PDE4D, increased cAMP activation leading to higher PKA phosphorylation of the β2-adrenergic-receptor, and decreased PKA phosphorylation of desmin after isoproterenol stimulation. Our findings identify PDE4DIP as a novel gene for slow AF and unravel its epistatic interaction with DES mutations in development of conduction disease and arrhythmia.

Inflammation as a risk factor for stroke in atrial fibrillation: data from a microarray data analysis

Objective

Stroke is a severe complication of atrial fibrillation (AF). We aimed to discover key genes and microRNAs related to stroke risk in patients with AF using bioinformatics analysis.

Methods

GSE66724 microarray data, including peripheral blood samples from eight patients with AF and stroke and eight patients with AF without stroke, were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between AF patients with and without stroke were identified using the GEO2R online tool. Functional enrichment analysis was performed using the DAVID database. A protein–protein interaction (PPI) network was obtained using the STRING database. MicroRNAs (miRs) targeting these DEGs were obtained from the miRNet database. A miR–DEG network was constructed using Cytoscape software.

Results

We identified 165 DEGs (141 upregulated and 24 downregulated). Enrichment analysis showed enrichment of certain inflammatory processes. The miR–DEG network revealed key genes, including MEF2A, CAND1, PELI1, and PDCD4, and microRNAs, including miR-1, miR-1-3p, miR-21, miR-21-5p, miR-192, miR-192-5p, miR-155, and miR-155-5p.

Conclusion

Dysregulation of certain genes and microRNAs involved in inflammation may be associated with a higher risk of stroke in patients with AF. Evaluating these biomarkers could improve prediction, prevention, and treatment of stroke in patients with AF.

Airway relaxation mechanisms and structural basis of osthole for improving lung function in asthma

Overuse of β2-adrenoceptor agonist bronchodilators evokes receptor desensitization, decreased efficacy, and an increased risk of death in asthma patients. Bronchodilators that do not target β2-adrenoceptors represent a critical unmet need for asthma management. Here, we characterize the utility of osthole, a coumarin derived from a traditional Chinese medicine, in preclinical models of asthma. In mouse precision-cut lung slices, osthole relaxed preconstricted airways, irrespective of β2-adrenoceptor desensitization. Osthole administered in murine asthma models attenuated airway hyperresponsiveness, a hallmark of asthma. Osthole inhibited phosphodiesterase 4D (PDE4D) activity to amplify autocrine prostaglandin E₂ signaling in airway smooth muscle cells that eventually triggered cAMP/PKA-dependent relaxation of airways. The crystal structure of the PDE4D complexed with osthole revealed that osthole bound to the catalytic site to prevent cAMP binding and hydrolysis. Together, our studies elucidate a specific molecular target and mechanism by which osthole induces airway relaxation. Identification of osthole binding sites on PDE4D will guide further development of bronchodilators that are not subject to tachyphylaxis and would thus avoid β2-adrenoceptor agonist resistance.

Phosphodiesterase-4 enzyme as a therapeutic target in neurological disorders

Phosphodiesterases (PDE) are a diverse family of enzymes (11 isoforms so far identified) responsible for the degradation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which are involved in several cellular and biochemical functions. Phosphodiesterase 4 (PDE4) is the major isoform within this group and is highly expressed in the mammalian brain. An inverse association between PDE4 and cAMP levels is the key mechanism in various pathophysiological conditions like airway inflammatory diseases-chronic obstruction pulmonary disease (COPD), asthma, psoriasis, rheumatoid arthritis, and neurological disorders etc. In 2011, roflumilast, a PDE4 inhibitor (PDE4I) was approved for the treatment of COPD. Subsequently, other PDE4 inhibitors (PDE4Is) like apremilast and crisaborole were approved by the Food and Drug Administration (FDA) for psoriasis, atopic dermatitis etc. Due to the adverse effects like unbearable nausea and vomiting, dose intolerance and diarrhoea, PDE4 inhibitors have very less clinical compliance. Efforts are being made to develop allosteric modulation with high specificity to PDE4 isoforms having better efficacy and lesser adverse effects. Interestingly, repositioning PDE4Is towards neurological disorders including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS) and sleep disorders, is gaining attention. This review is an attempt to summarize the data on the effects of PDE4 overexpression in neurological disorders and the use of PDE4Is and newer allosteric modulators as therapeutic options. We have also compiled a list of on-going clinical trials on PDE4 inhibitors in neurological disorders.

Docking Studies of Curcumin and Analogues with Various Phosphodiesterase 4 Subtypes

INTRODUCTION

The primary aim of this study is to understand the binding of curcumin and its analogues to different PDE4 subtypes and identify the role of PDE4 subtype inhibition in the anti-inflammatory property of curcumin. Docking analysis has been used to acquire the above mentioned structural information and this has been further used for designing of curcumin derivatives with better anti-inflammatory activity.

MATERIALS AND METHODS

Curcumin and its analogues were subjected to docking using PDE4A, PDE4B, PDE4C and PDE4D as the targets. A data set comprising 18 analogues of curcumin, was used as ligands for docking of PDE4 subtypes. Curcumin was used as the standard for comparison. Docking was performed using AutoDock Vina 1.1.2 software integrated in LigandScout 4.1. During this process water molecules were removed from proteins, charges were added and receptor structures were minimised by applying suitable force fields. The docking scores were compared, and the selectivity of compounds for PDE4B over PDE4D was calculated as well.

RESULTS

All curcumin analogues used in the study showed good binding affinity with all PDE4 subtypes, with evident selectivity towards PDE4B subtype. Analogue A11 provides the highest binding affinity among all ligands.

CONCLUSION

Curcumin and analogues have moderate to strong affinity towards all PDE4 subtypes and have evident selectivity towards PDE4B. The Oxygen atom of the methoxy group plays a key role in PDE4B binding and any alterations could interfere with the binding. Tetrahydropyran side chain and heterocyclic rings are also suggested to be helpful in PDE4B binding.

Cyclic nucleotide phosphodiesterases (PDEs) and endothelial function in ischaemic stroke. A review

BACKGROUND

Endothelial dysfunction is a hallmark of cerebrovascular disease, including ischemic stroke. Modulating endothelial signalling by cyclic nucleotides, cAMP and cGMP, is a potential therapeutic target in stroke. Inhibitors of the cyclic nucleotide degrading phosphodiesterase (PDE) enzymes may restore cerebral endothelial function. Current knowledge on PDE distribution and function in cerebral endothelial cells is sparse. This review explores data on PDE distribution and effects of PDEi in cerebral endothelial cells and identifies which PDEs are potential treatment targets in stroke.

METHOD

We performed a systematic search of electronic databases (Medline and Embase). Our search terms were cerebral ischaemia, cerebral endothelial cells, cyclic nucleotide, phosphodiesterase and phosphodiesterase inhibitors.

RESULTS

We found 23 publications which described effects of selective inhibitors of only three PDE families on endothelial function in ischemic stroke. PDE3 inhibitors (PDE3i) (11 publications) and PDE4 inhibitors (PDE4i) (3 publications) showed anti-inflammatory, anti-apoptotic or pro-angiogenic effects. PDE3i also reduced leucocyte infiltration and MMP-9 expression. Both PDE3i and PDE4i increased expression of tight junction proteins and protected the blood-brain barrier. PDE5 inhibitors (PDE5i) (6 publications) reduced inflammation and apoptosis. In preclinical models, PDE5i enhanced cGMP/NO signalling associated with microvascular angiogenesis, increased cerebral blood flow and improved functional recovery. Non-specific PDEi (3 publications) had mainly anti-inflammatory effects.

CONCLUSION

This review demonstrates that non-selective and selective PDEi of PDE3, PDE4 and PDE5 modulated endothelial function in cerebral ischemic stroke by regulating processes involved in vascular repair and neuroprotection and thus reduced cell death and inflammation. Of note, they promoted angiogenesis, microcirculation and improved functional recovery; all are important in stroke prevention and recovery, and effects should be further evaluated in humans.

Extended Risk Factors for Stroke Prevention

Stroke causes disability and high mortality, while it can be prevented by increasing public awareness of risk factors. The common known risk factors are hypertension, atrial fibrillation, heart failure, smoking, alcohol consumption, low physical activity, overweight and hypercholesterolemia. However, the deep understanding of risk factors is limited. Moreover, more risk factor emerges in recent years. To further increase the awareness of risk factors for stroke prevention, this review indicates the reasonable application of antihypertensive agents according to the age-dependent changes of hypertension, and some new risk factors including chronic kidney disease, obstructive sleep apnea, migraine with aura, working environment, genetic factors and air pollution. Therefore, internal risk factors (e.g. heredity, hypertension, hyperglycemia) and external risk factors (e.g. working environment, air pollution) are both important for stroke prevention. All of these are reviewed to provide more information for the pre-hospital prevention and management, and the future clinical studies.

Association and interaction of genetic variants with occurrence of ischemic stroke among Brazilian patients

Ischemic Stroke (IS) is a severe and complex disorder of high morbidity and mortality rates associated with clinical, environmental, and genetic predisposing factors. Despite previous studies have associated genetic variants to stroke, inconsistent results from different populations pointed to the genetic heterogeneity for IS. Therefore, we may hypothesize that an interaction effect among genetic variants could contribute to IS occurrence rather than genetic variants independently. In this context, we investigated the association and interaction between genetic variants and large-artery atherosclerosis IS (LAAS-IS) and cardioembolic IS (CE-IS). We genotyped 435 patients (195 LAAS-IS; 240 CE-IS) and 535 controls from a population of Joinville, Santa Catarina, Brazil. Association and interaction analysis were performed by chi-square test and Multifactor-dimensionality Reduction test. We found an association between rs2383207*A allele, nearby CDKN2B-AS1, and LAAS-IS [OR 2.35 (95% CI = 1.79-3.08); p = 4.66 × 10^-10]. We found an interaction among rs2910829, rs966221 and rs152312, with an accuracy of 0.62 (p = 4.3 × 10^-5) demonstrating the interaction effect among variants from different genes can contribute to CE-IS risk. Further prediction analysis confirmed that clinical information, such as hypertension and dyslipidemia, presented high accuracy to predict LAAS-IS (86.47%) and CE-IS (90.47%); however, the inclusion of genetic variant information did not increase the accuracy.

LncRNA XIST regulates myocardial infarction by targeting miR-130a-3p

The study was used to probe long noncoding RNA X-inactive specific transcript (lncRNA XIST) RNA expression profile and its influence on cell cycle, proliferation, and apoptosis in myocardial cells. We also aimed to explore the possible meditating relationship between XIST, PDE4D, and miR-130a-3p. Gene differential analysis was carried out using human lncRNA Microarray V3.0. quantitative real-time PCR was used to test mRNA expressions of XIST, miR-130a-3p, and PDE4D in normal cells and postmyocardial infarction (MI) cells. Western blot was applied to determine the protein expression profile of PED4D. Changes in viability and cell cycle/apoptosis of post-MI myocardial cells after silencing of XIST or PDE4D were investigated by MTT assay and flow cytometry, respectively. The targeting relationship between miR-130a-3p and XIST, PDE4D in myocardial cells were verified by dual luciferase reporter assay. Simulated MI environment was constructed by performing anoxic preconditioning in normal cells to probe the influence of XIST on myocardial cell apoptosis. XIST and PDE4D were overexpressed in post-MI myocardial cells, whereas miR-130a-3p was underexpressed in post-MI myocardial cells. High-expressed XIST and PDE4D both promoted myocardial cell apoptosis. High-expressed XIST also inhibited myocardial cell proliferation. XIST-downregulated miR-130a-3p and PDE4D was a direct target of miR-130a-3p. LncRNA XIST promotes MI by targeting miR-130a-3p. MI induced by PDE4D can be reversed by miR-130a-3p.

Targeting phosphodiesterase 4 as a potential therapeutic strategy for enhancing neuroplasticity following ischemic stroke

Sensorimotor recovery following ischemic stroke is highly related with structural modification and functional reorganization of residual brain tissues. Manipulations, such as treatment with small molecules, have been shown to enhance the synaptic plasticity and contribute to the recovery. Activation of the cAMP/CREB pathway is one of the pivotal approaches stimulating neuroplasticity. Phosphodiesterase 4 (PDE4) is a major enzyme controlling the hydrolysis of cAMP in the brain. Accumulating evidences have shown that inhibition of PDE4 is beneficial for the functional recovery after cerebral ischemia; i. subtype D of PDE4 (PDE4D) is viewed as a risk factor for ischemic stroke; ii. inhibition of PDE4 enhances neurological behaviors, such as learning and memory, after stroke in rodents; iii.PDE4 inhibition increases dendritic density, synaptic plasticity and neurogenesis; iv. activation of cAMP/CREB signaling by PDE4 inhibition causes an endogenous increase of BDNF, which is a potent modulator of neuroplasticity; v. PDE4 inhibition is believed to restrict neuroinflammation during ischemic stroke. Cumulatively, these findings provide a link between PDE4 inhibition and neuroplasticity after cerebral ischemia. Here, we summarized the possible roles of PDE4 inhibition in the recovery of cerebral stroke with an emphasis on neuroplasticity. We also made some recommendations for future research.

Expanding the phenotypic spectrum of variants in PDE4D/PRKAR1A: from acrodysostosis to acroscyphodysplasia

Acrodysostosis (MIM 101800) is a dominantly inherited condition associating (1) skeletal features (short stature, facial dysostosis, and brachydactyly with cone-shaped epiphyses), (2) resistance to hormones and (3) possible intellectual disability. Acroscyphodysplasia (MIM 250215) is characterized by growth retardation, brachydactyly, and knee epiphyses embedded in cup-shaped metaphyses. We and others have identified PDE4D or PRKAR1A variants in acrodysostosis; PDE4D variants have been reported in three cases of acroscyphodysplasia. Our study aimed at reviewing the clinical and molecular findings in a cohort of 27 acrodysostosis and 5 acroscyphodysplasia cases. Among the acrodysostosis cases, we identified 9 heterozygous de novo PRKAR1A variants and 11 heterozygous PDE4D variants. The 7 patients without variants presented with symptoms of acrodysostosis (brachydactyly and cone-shaped epiphyses), but none had the characteristic facial dysostosis. In the acroscyphodysplasia cases, we identified 2 PDE4D variants. For 2 of the 3 negative cases, medical records revealed early severe infection, which has been described in some reports of acroscyphodysplasia. Subdividing our series of acrodysostosis based on the disease-causing gene, we confirmed genotype-phenotype correlations. Hormone resistance was consistently observed in patients carrying PRKAR1A variants, whereas no hormone resistance was observed in 9 patients with PDE4D variants. All patients with PDE4D variants shared characteristic facial features (midface hypoplasia with nasal hypoplasia) and some degree of intellectual disability. Our findings of PDE4D variants in two cases of acroscyphodysplasia support that PDE4D may be responsible for this severe skeletal dysplasia. We eventually emphasize the importance of some specific assessments in the long-term follow up, including cardiovascular and thromboembolic risk factors.

Compartmentalized cyclic nucleotides have opposing effects on regulation of hypertrophic phospholipase Cε signaling in cardiac myocytes

In cardiac myocytes activation of an exchange factor activated by cAMP (Epac) leads to activation of phospholipase Cε (PLCε)-dependent hydrolysis of phosphatidylinositol 4-phosphate (PI4P) in the Golgi apparatus a process critical for development of cardiac hypertrophy. Here we show that β-adrenergic receptor (βAR) stimulation does not stimulate this pathway in the presence of the broad spectrum phosphodiesterase (PDE) inhibitor IBMX, but selective PDE3 inhibition revealed βAR-dependent PI4P depletion. On the other hand, selective inhibition of PDE2 or PDE9A blocked endothelin-1 (ET-1) and cAMP-dependent PI4P hydrolysis by PLCε. Direct activation of protein kinase A (PKA), protein kinase G (PKG), or the atrial natriuretic factor (ANF) receptor abolished PI4P hydrolysis in response to multiple upstream stimuli. These results reveal distinct pools of cyclic nucleotides that either inhibit PLCε at the Golgi through PKA/PKG, or activate PLCε at the Golgi through Epac. These data together reveal a new mechanism by which ANF and selective PDE inhibitors can protect against cardiac hypertrophy.

Association between PDE4D rs966221 polymorphism and risk of ischemic stroke: a systematic review and meta-analysis

PDE4D polymorphism (SNP83/rs966221) was reported to be associated with the susceptibility to ischemic stroke (IS), however, the results were inconclusive. An electronic search of Embase, PubMed, CNKI and Wan Fang Date was performed to identify relevant studies published throughout April 2017. A total of 26 studies were enrolled in the analysis. No significant association between the rs9662221 polymorphism and IS was observed in the overall analysis. Nevertheless, in the subgroup analysis, our results showed a significant association between the SNP83 polymorphism and IS in CC+ CT vs. TT (OR = 1.19, 95% CI: 1.02-1.38), CT vs.TT (OR = 1.14, 95% CI: 1.01-1.29) and C vs. T (OR = 1.25, 95% CI: 1.06-1.48) in Asian population. But we did not found any association in CC vs. CT + TT (OR = 1.2, 95% CI: 0.9-1.61) and CC vs. TT (OR = 1.26, 95% CI: 0.91-1.75) in the Asian populations. Meantime, no significant correlations were observed under the five genetic model in Caucasian population (p > 0.05). In conclusion, our meta-analysis demonstrated that the SNP83 polymorphism in the PDE4D gene might contribute to IS susceptibility especially in Asian populations. Whereas the relationship of the polymorphism to the disease in Caucasian population was still in controversial. In future, additional well designed studies with larger sample sizes are still required to further elucidate this association.

Polymorphisms of MTHFR, eNOS, ACE, AGT, ApoE, PON1, PDE4D, and Ischemic Stroke: Meta-Analysis

INTRODUCTION

The association between ischemic stroke and genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR; 677C>T and 1298A>C), endothelial nitric oxide synthase (eNOS; -786T>C, +894G>T, and variable number tandem repeat [VNTR]), phosphodiesterase 4D (PDE4D; SNPs 83 and 87), angiotensin-converting enzyme (ACE) I/D, angiotensinogen (AGT) 235M>T, paraoxonase 1 (PON1) 192Q>R, and apolipoprotein E (ApoE) ε2ε3ε4 remains inconclusive. Therefore, this updated meta-analysis aimed to clarify the presumed influence of genetic polymorphisms on ischemic stroke by meta-analyzing the comprehensive coverage of all individual association studies.

METHODS

All case-control studies published in different languages such as English, Japanese, Korean, Spanish, Chinese, Hungarian, Ukrainian, or Russian were identified from databases. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated via fixed- and random-effect models. Sensitivity analysis, heterogeneity test, Hardy Weinberg Equilibrium, and Egger's regression analyses were performed in this study.

RESULTS

A total of 490 case-control studies with 138,592 cases and 159,314 controls were included in this meta-analysis. Pooled ORs from all the genetic models indicated that MTHFR 677TT and 1298CC, eNOS +894TT and VNTR, PDE4D SNP 83, ACE DD, AGT 235TT, PON1 192RR, and ApoE ε4 polymorphisms were increasing the risks of ischemic stroke. Nevertheless, PDE4D SNP 87 and eNOS -786T>C polymorphisms are not associated with ischemic stroke risks.

CONCLUSIONS

Hence, the evidence from this meta-analysis concluded that MTHFR (677C>T and 1298A>C), eNOS (+894G>T and VNTR), PDE4D SNP 83, ACE I/D, AGT 235M>T, PON1 192Q>R, and ApoE ε2ε3ε4 polymorphisms predispose individuals to ischemic stroke.

A meta-analysis of PDE-gene polymorphism and cerebral infarction risk

Previous studies identified that phosphodiesterase 4D (PDE4D) gene polymorphism might be associated with cerebral infarction or ischemic stroke, and hemorrhagic stroke in human populations. However, as yet, no meta-analysis has revealed any detailed association. We retrospectively reviewed studies regarding the relationship of PDE4D gene polymorphism with ischemic stroke (IS) published during the period January 2003 to September 2012. According to the inclusion criteria, 9 of 105 initial studies were included in the subsequent analysis. The PubMed, Embase and CNKI of China were searched to identify the relevant studies. A total of 186 young patients with IS were included for the meta-analysis and 232 matched control subjects were enrolled and results were presented. The association of PDE4D gene polymorphism with IS in various populations was examined. The results suggested that single nucleotide polymorphism (SNP), SNP 83 in PDE4D gene was significantly related with susceptibility to IS. The meta-analysis also showed that PDE4D gene was associated with an enhanced risk of IS. The meta-analysis suggested that PDE4D SNP 87 constitutes an independent risk factor for IS development. To the best of our knowledge, the present meta-analysis reveals a number of possible associations between PDE4D gene polymorphism and IS.

The cyclic AMP phosphodiesterase 4D5 (PDE4D5)/receptor for activated C-kinase 1 (RACK1) signalling complex as a sensor of the extracellular nano-environment

The cyclic AMP and protein kinase C (PKC) signalling pathways regulate a wide range of cellular processes that require tight control, including cell proliferation and differentiation, metabolism and inflammation. The identification of a protein complex formed by receptor for activated C kinase 1 (RACK1), a scaffold protein for protein kinase C (PKC), and the cyclic AMP-specific phosphodiesterase, PDE4D5, demonstrates a potential mechanism for crosstalk between these two signalling routes. Indeed, RACK1-bound PDE4D5 is activated by PKCα, providing a route through which the PKC pathway can control cellular cyclic AMP levels. Although RACK1 does not appear to affect the intracellular localisation of PDE4D5, it does afford structural stability, providing protection against denaturation, and increases the susceptibility of PDE4D5 to inhibition by cyclic AMP-elevating pharmaceuticals, such as rolipram. In addition, RACK1 can recruit PDE4D5 and PKC to intracellular protein complexes that control diverse cellular functions, including activated G protein-coupled receptors (GPCRs) and integrins clustered at focal adhesions. Through its ability to regulate local cyclic AMP levels in the vicinity of these multimeric receptor complexes, the RACK1/PDE4D5 signalling unit therefore has the potential to modify the quality of incoming signals from diverse extracellular cues, ranging from neurotransmitters and hormones to nanometric topology. Indeed, PDE4D5 and RACK1 have been found to form a tertiary complex with integrin-activated focal adhesion kinase (FAK), which localises to cellular focal adhesion sites. This supports PDE4D5 and RACK1 as potential regulators of cell adhesion, spreading and migration through the non-classical exchange protein activated by cyclic AMP (EPAC1)/Rap1 signalling route.

Nanodomain Regulation of Cardiac Cyclic Nucleotide Signaling by Phosphodiesterases

Cyclic nucleotide phosphodiesterases (PDEs) form an 11-member superfamily comprising 100 different isoforms that regulate the second messengers cyclic adenosine or guanosine 3',5'-monophosphate (cAMP or cGMP). These PDE isoforms differ with respect to substrate selectivity and their localized control of cAMP and cGMP within nanodomains that target specific cellular pools and synthesis pathways for the cyclic nucleotides. Seven PDE family members are physiologically relevant to regulating cardiac function, disease remodeling of the heart, or both: PDE1 and PDE2, both dual-substrate (cAMP and cGMP) esterases; PDE3, PDE4, and PDE8, which principally hydrolyze cAMP; and PDE5A and PDE9A, which target cGMP. New insights regarding the different roles of PDEs in health and disease and their local signaling control are broadening the potential therapeutic utility for PDE-selective inhibitors. In this review, we discuss these PDEs, focusing on the different mechanisms by which they control cardiac function in health and disease by regulating intracellular nanodomains.