A Homozygous Splicing Mutation in PDE2A in a Family With Atypical Rett Syndrome

Defects in AMPAR trafficking and microglia activation underlie socio-cognitive deficits associated to decreased expression of phosphodiesterase 2 a

Phosphodiesterase 2 A (PDE2A) is an enzyme involved in the homeostasis of cAMP and cGMP and is the most highly expressed PDE in human brain regions critical for socio-cognitive behavior. In cerebral cortex and hippocampus, PDE2A expression level is upregulated in Fmr1-KO mice, a model of the Fragile X Syndrome (FXS), the most common form of inherited intellectual disability (ID) and autism spectrum disorder (ASD). Indeed, PDE2A translation is negatively modulated by FMRP, whose functional absence causes FXS. While the pharmacological inhibition of PDE2A has been associated to its pro-cognitive role in normal animals and in models of ID and ASD, homozygous PDE2A mutations have been identified in patients affected by ID, ASD and epilepsy. To clarify this apparent paradox about the role of PDE2A in brain development, we characterized here Pde2a+/- mice (homozygote animals being not viable) at the behavioral, cellular, molecular and electrophysiological levels. Pde2a+/- females display a milder form of the disorder with reduced cognitive performance in adulthood, conversely males show severe socio-cognitive deficits throughout their life. In males, these phenotypes are associated with microglia activation, elevated glutathione levels and increased externalization of Glutamate receptor (GluR1) in CA1, producing reduced mGluR-dependent Long-term Depression. Overall, our results reveal molecular targets of the PDE2A-dependent pathway underlying socio-cognitive performance. These results clarify the mechanism of action of pro-cognitive drugs based on PDE2A inactivation, which have been shown to be promising therapeutic approaches for Alzheimer's disease, schizophrenia, FXS as well as other forms of ASD.

Phosphodiesterase and psychiatric disorders: a two-sample Mendelian randomization study

BACKGROUND

Phosphodiesterases (PDEs) have been associated with psychiatric disorders in observational studies; however, the causality of associations remains unestablished.

METHODS

Specifically, cyclic nucleotide PDEs were collected from genome-wide association studies (GWASs), including PDEs obtained by hydrolyzing both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) (PDE1A, PDE2A, and PDE3A), specific to cGMP (PDE5A, PDE6D, and PDE9A) and cAMP (PDE4D and PDE7A). We performed a bidirectional two-sample Mendelian randomization (MR) analysis to investigate the relationship between PDEs and nine psychiatric disorders. The inverse-variance-weighted (IVW) method, MR-Egger, and weighted median were used to estimate causal effects. The Cochran's Q test, MR-Egger intercept test, MR Steiger test, leave-one-out analyses, funnel plot, and MR pleiotropy residual sum and outlier (MR-PRESSO) were used for sensitivity analyses.

RESULTS

The PDEs specific to cAMP were associated with higher-odds psychiatric disorders. For example, PDE4D and schizophrenia (SCZ) (odds ratios (OR) = 1.0531, PIVW = 0.0414), as well as major depressive disorder (MDD) (OR = 1.0329, PIVW = 0.0011). Similarly, PDE7A was associated with higher odds of attention-deficit/hyperactivity disorder (ADHD) (OR = 1.0861, PIVW = 0.0038). Exploring specific PDE subtypes and increase intracellular cAMP levels can inform the development of targeted interventions. We also observed PDEs (which hydrolyzes both cAMP and cGMP) was associated with psychiatric disorders [OR of PDE1A was 1.0836 for autism spectrum disorder; OR of PDE2A was 0.8968 for Tourette syndrome (TS) and 0.9449 for SCZ; and OR of PDE3A was 0.9796 for MDD; P < 0.05]. Furthermore, psychiatric disorders also had some causal effects on PDEs [obsessive-compulsive disorder on increased PDE6D and decreased PDE2A and PDE4D; anorexia nervosa on decreased PDE9A]. The results of MR were found to be robust using multiple sensitivity analysis.

CONCLUSIONS

In this study, potential causal relationships between plasma PDE proteins and psychiatric disorders were established. Exploring other PDE subtypes not included in this study could provide a more comprehensive understanding of the role of PDEs in psychiatric disorders. The development of specific medications targeting PDE subtypes may be a promising therapeutic approach for treating psychiatric disorders.

A homozygous founder variant in PDE2A causes paroxysmal dyskinesia with intellectual disability

Intellectual developmental disorder with paroxysmal dyskinesia or seizures (IDDPADS, OMIM#619150) is an ultra-rare childhood-onset autosomal recessive movement disorder manifesting paroxysmal dyskinesia, global developmental delay, impaired cognition, progressive psychomotor deterioration and/or drug-refractory seizures. We investigated three consanguineous Pakistani families with six affected individuals presenting overlapping phenotypes partially consistent with the reported characteristics of IDDPADS. Whole exome sequencing identified a novel missense variant in Phosphodiesterase 2A (PDE2A): NM_002599.4: c.1514T > C p.(Phe505Ser) that segregated with the disease status of individuals in these families. Retrospectively, we performed haplotype analysis that revealed a 3.16 Mb shared haplotype at 11q13.4 among three families suggesting a founder effect in this region. Moreover, we also observed abnormal mitochondrial morphology in patient fibroblasts compared to controls. Belonging to diverse age groups (13 years-60 years), patients presented paroxysmal dyskinesia, developmental delay, cognitive abnormalities, speech impairment, and drug-refractory seizures with variable onset of disease (as early as 3 months of age to 7 years). Together with the previous reports, we observed that intellectual disability, progressive psychomotor deterioration, and drug-refractory seizures are consistent outcomes of the disease. However, permanent choreodystonia showed variability. We also noticed that the later onset of paroxysmal dyskinesia manifests severe attacks in terms of duration. Being the first report from Pakistan, we add to the clinical and mutation spectrum of PDE2A-related recessive disease raising the total number of patients from six to 12 and variants from five to six. Together, with our findings, the role of PDE2A is strengthened in critical physio-neurological processes.

Phosphodiesterase 2A inhibition corrects the aberrant behavioral traits observed in genetic and environmental preclinical models of Autism Spectrum Disorder

Pharmacological inhibition of phosphodiesterase 2A (PDE2A), which catalyzes the hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), has recently been proposed as a novel therapeutic tool for Fragile X Syndrome (FXS), the leading monogenic cause of Autism Spectrum Disorder (ASD). Here, we investigated the role of PDE2A in ASD pathogenesis using two rat models that reflect one of either the genetic or environmental factors involved in the human disease: the genetic Fmr1-^Δexon 8 rat model and the environmental rat model based on prenatal exposure to valproic acid (VPA, 500 mg/kg). Prior to behavioral testing, the offspring was treated with the PDE2A inhibitor BAY607550 (0.05 mg/kg at infancy, 0.1 mg/kg at adolescence and adulthood). Socio-communicative symptoms were assessed in both models through the ultrasonic vocalization test at infancy and three-chamber test at adolescence and adulthood, while cognitive impairments were assessed by the novel object recognition test in Fmr1-^Δexon 8 rats (adolescence and adulthood) and by the inhibitory avoidance test in VPA-exposed rats (adulthood). PDE2A enzymatic activity in VPA-exposed infant rats was also assessed. In line with the increased PDE2A enzymatic activity previously observed in the brain of Fmr1-KO animals, we found an altered upstream regulation of PDE2A activity in the brain of VPA-exposed rats at an early developmental age (p < 0.05). Pharmacological inhibition of PDE2A normalized the communicative (p < 0.01, p < 0.05), social (p < 0.001, p < 0.05), and cognitive impairment (p < 0.001) displayed by both Fmr1-^Δexon 8 and VPA-exposed rats. Altogether, these data highlight a key role of PDE2A in brain development and point to PDE2A inhibition as a promising pharmacological approach for the deficits common to both FXS and ASD.

Clinical significance of PDE2A in prognosis and immune infiltration in gastrointestinal cancer based on bioinformatics analysis

BACKGROUND

Gastrointestinal cancer is one of the most common malignant cancers, but its prognosis is still poor. Exploring potential biomarkers is an important aspect of cancer research. We intended to explore potential biomarkers for gastrointestinal cancer using bioinformatics methods.

AIM

To explore the correlation between the expression of PDE2A and immune infiltration in gastrointestinal cancer, and to investigate the prognostic value of PDE2A in gastrointestinal cancer.

METHODS

The mRNA and protein expression of PDE2A in different gastrointestinal cancers was analyzed based on the HPA, TIMER, and UALCAN databases. GEPIA database was used to investigate the effect of PDE2A on prognosis of patients with different gastrointestinal cancers. The relationship between PDE2A expression and immune infiltration was analyzed using the TIMER database. Frequencies of PDE2A mutations were analyzed using cBioPortal database. Protein-protein interaction network analysis of PDE2A was based on the STRING database.

RESULTS

The mRNA and protein expression of PDE2A in liver hepatocellular carcinoma (LIHC), stomach adenocarcinoma (STAD), pancreatic adenocarcinoma (PAAD), colon adenocarcinoma (COAD), and esophageal carcinoma (ESCA) was lower than that in normal adjacent tissues. Patients with LIHC and PAAD with high PDE2A expression had a better prognosis. The expression of PDE2A was positively or negatively correlated with different immune cells such as CD4+ T cells, CD8+ T cells, B cells, macrophages, and neutrophils in LIHC, STAD, PAAD, COAD, and ESCA. Finally, there were missense mutations in PDE2A gene in STAD, PAAD, COAD, and ESCA.

CONCLUSION

The expression of PDE2A is related to immune infiltration in gastrointestinal cancer. Patients with LIHC and PAAD with high PDE2A expression have a better prognosis. PDE2A may be a potential immunotherapy target and prognostic marker for gastrointestinal cancer.

Role of phosphodiesterases in the pathophysiology of neurodevelopmental disorders

Phosphodiesterases (PDEs) are enzymes involved in the homeostasis of both cAMP and cGMP. They are members of a family of proteins that includes 11 subfamilies with different substrate specificities. Their main function is to catalyze the hydrolysis of cAMP, cGMP, or both. cAMP and cGMP are two key second messengers that modulate a wide array of intracellular processes and neurobehavioral functions, including memory and cognition. Even if these enzymes are present in all tissues, we focused on those PDEs that are expressed in the brain. We took into consideration genetic variants in patients affected by neurodevelopmental disorders, phenotypes of animal models, and pharmacological effects of PDE inhibitors, a class of drugs in rapid evolution and increasing application to brain disorders. Collectively, these data indicate the potential of PDE modulators to treat neurodevelopmental diseases characterized by learning and memory impairment, alteration of behaviors associated with depression, and deficits in social interaction. Indeed, clinical trials are in progress to treat patients with Alzheimer's disease, schizophrenia, depression, and autism spectrum disorders. Among the most recent results, the application of some PDE inhibitors (PDE2A, PDE3, PDE4/4D, and PDE10A) to treat neurodevelopmental diseases, including autism spectrum disorders and intellectual disability, is a significant advance, since no specific therapies are available for these disorders that have a large prevalence. In addition, to highlight the role of several PDEs in normal and pathological neurodevelopment, we focused here on the deregulation of cAMP and/or cGMP in Down Syndrome, Fragile X Syndrome, Rett Syndrome, and intellectual disability associated with the CC2D1A gene.