Sanchez-Castillo, C. | Search bioRxiv

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↗

bioRxiv2023

A slc38a8 mouse model of FHONDA syndrome faithfully recapitulates the visual deficits of albinism without pigmentation defects

PurposeWe aimed to generate and phenotype a mouse model of FHONDA (Foveal Hypoplasia, Optic Nerve Decussation Defects, and Anterior Segment Dysgenesis), a rare disease associated with mutations in SLC38A8 that causes severe visual alterations similar to albinism without affecting pigmentation. MethodsThe FHONDA mouse model was generated with CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 technology using an RNA guide targeting the Scl38a8 murine locus. The resulting mice were backcrossed to C57BL/6J. Melanin content was measured using spectrophotometry. Retinal cell architecture was analyzed through light and electron microscopy. Retinal projections to the brain were evaluated with anterograde labelling in embryos and adults. Visual function was assessed by electroretinography (ERG) and the optomotor test (OT). ResultsFrom numerous Slc38a8 mouse mutant alleles generated, we selected one that encodes a truncated protein (p.196Pro*, equivalent to p.199Pro* in the human protein) closely resembling a mutant allele described in patients (p.200Gln*). Slc38a8 mutant mice exhibit wild-type eye and coat pigmentation with comparable melanin contents. Subcellular abnormalities were observed in retinal pigment epithelium cells of Slc38a8 mutant mice. Anterograde labelling experiments of retinal projections in embryos and adults showed a reduction of ipsilateral fibers. Functional visual analyses revealed a decreased ERG response in scotopic conditions and a reduction of visual acuity in mutant mice measured by OT. ConclusionsSlc38a8 mutant mice recapitulate the phenotype of FHONDA patients concerning their normal pigmentation and their abnormal visual system, as observed in all types of albinism. These mice will be helpful in better understanding the pathophysiology of this genetic condition.

neuroscience↗