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.

A reappraisal of transcriptional regulation by NR5A1 and beta-catenin in adrenocortical carcinoma.

Background: Overexpression of the transcription factor NR5A1 and constitutive activation of canonical Wnt signalling leading to nuclear translocation of beta-catenin are hallmarks of malignancy in adrenocortical carcinoma (ACC). Based on the analysis of genomic profiles in H295R ACC cells, Mohan et al. (Cancer Res. 2023; 83: 2123-2141) recently suggested that a major determinant driving proliferation and differentiation in malignant ACC is the interaction of NR5A1 and beta-catenin on chromatin to regulate gene expression. Methods: I reanalyzed the same set of data generated by Mohan et al. and other published data of knockdown-validated NR5A1 and beta-catenin target genes. Results: Beta-catenin is mainly found in association to canonical T cell factor/lymphoid enhancer factor (TCF/LEF) motifs in genomic DNA. NR5A1 and beta-catenin regulate distinct target gene sets in ACC cells. Conclusion: Overall, my analysis suggests a model where NR5A1 overexpression and beta-catenin activation principally act independently, rather than functionally interacting, to drive ACC malignancy.