AKT is necessary for neuronal hypertrophy and epilepsy caused by <i>Pten</i> knockout

Phosphatase and tensin homolog on chromosome 10 (PTEN) is a key negative regulator of the AKT/mTOR signaling pathway. Mutations in PTEN are highly implicated in Autism Spectrum Disorder (ASD), epilepsy, congenital hydrocephaly, and macrocephaly. While the conditional genetic knockout of Pten in murine neurons results in hypertrophy, increased migration, excitatory synaptogenesis, hyperexcitability, and epileptiform activity, the specific downstream signalling mediators of these pathologies remain to be fully elucidated. Using retroviral-mediated genetic manipulation of individual neurons within the Cre-lox system, we have analyzed pathway outputs in response to the manipulation of various genes using immunohistochemistry, confocal microscopy, and extensive morphological analyses, alongside whole-cell patch-clamp electrophysiology and 120-hour video-EEG monitoring for seizure assessment. Here, we demonstrate that signaling through AKT is necessary for the development of neuronal overgrowth, increased excitatory synapse formation, excessive migration, and hyperexcitability fueled by the loss of PTEN function. Notably, the concurrent deletion of Akt1 and Akt3 isoforms was sufficient to effectively rescue hypertrophic neuronal morphology and physiology. These findings establish AKT as the essential mediator through which PTEN deficiency manifests, providing a transformative therapeutic target to correct the morphological and functional defects central to PTEN-related neurodevelopmental disorders.