Boers-Escuder, C. | bioRxiv Science

bioRxiv2025

Astrocytic PI3Kα controls synaptic plasticity and cognitive function via serine metabolism

Astrocytes are known to modulate neuronal activity by gliotransmission and through metabolic regulation. However, the connection between these two processes is still poorly defined. In this work we show that the p110 isoform of the phosphatidylinositol 3-kinase (PI3K) in astrocytes is required for long-term potentiation (LTP) and has an impact on learning and memory. Using a specific deletion of p110 from hippocampal astrocytes in adult mice, we found that LTP depends on astrocytic p110 to sustain D-serine levels for the activation of NMDA receptors during LTP induction. This requirement is based on the L-serine biosynthetic pathway of the astrocyte, which is defective in the absence of p110 because of a reduced glycolytic flux. Accordingly, the behavioral impairment in mice lacking p110 can be rescued by in vivo administration of L-serine. These results link for the first time the function of PI3K in astrocytes to cerebral metabolism and its influence in synaptic plasticity and cognition.

neuroscience↗

bioRxiv2024

ASD-ASSOCIATED CNTNAP2 VARIANTS DISRUPT NEURONAL ARBORIZATION THROUGH IMPAIRED REGULATION BY ECTODOMAIN SHEDDING

Ectodomain shedding (ES) is a process by which a protease cleaves the extracellular portion of membrane-bound proteins, releasing soluble fragments that influence diverse cellular functions. ES is critical in neurodevelopment, plasticity, and neurodegenerative disorders, such as Alzheimers disease, and has recently been implicated in neurodevelopmental conditions, including autism spectrum disorders (ASD). Contactin-associated protein-like 2 (CNTNAP2) is an adhesion molecule regulated by ES, releasing a soluble ectodomain (sCNTNAP2) that enhances neuronal synchrony. CNTNAP2 is implicated in ASD, schizophrenia, and cortical dysplasia focal epilepsy syndrome (CDFE) and it is known to regulate neuronal arborization, as well as dendritic spine maturation and maintenance. However, little is known about how neuroplasticity impacts ES or the role of CNTNAP2 ES in dendritic arborization. Here, we show that the brain sheddome is enriched in shed ectodomains that regulate neuronal projections, and that its molecular and functional composition is modulated by sensory deprivation in a sex dependent manner, with a decrease in sCNTNAP2 levels observed only in male mice. Furthermore, we demonstrate that sCNTNAP2 promotes dendritic arborization, while ASD-associated CNTNAP2 variants present reduced sCNTNAP2 levels in culture and decreased neuronal branching. Together, these findings underscore the role of ES in neuroplasticity and ASD and reveal how CNTNAP2 genetic variations disrupt its regulation by ES, leading to altered dendritic branching.

neuroscience↗