RESTORING INTRAORGANELLAR PH HOMEOSTASIS AS A POTENTIAL THERAPEUTIC TARGET FOR TBC1D24-ASSOCIATED EPILEPSY

Epilepsy and neurodevelopmental disorders are frequently associated with alterations in intracellular trafficking, organelle homeostasis, and neuronal excitability. Recently, proteins containing the TLDc domain, such as TBC1D24, have been reported to bind the proton pump V-ATPase, responsible for the acidification of intracellular organelles. In the absence of TBC1D24, defective acidification of endo-lysosomal compartments and synaptic vesicles (SVs), as well as impaired autophagy occurs in primary neurons in vitro. Several mutations in TBC1D24 have been identified in patients with epilepsy-associated neurodevelopmental disorders. The molecular mechanisms underlying brain hyperexcitability associated with TBC1D24-loss of function and its interplay with neuronal pH homeostasis, remain largely unexplored. Here we employed a novel Tamoxifen (TAM)-inducible conditional knockout mouse model for Tbc1d24 (Tbc1d24-cKO) to study epileptogenesis, seizures and behavioral profile in adult mice following Tbc1d24 loss of function. Electroencephalography/electromyography (EEG/EMG) recordings, together with behavioral assessments, were used to characterize the epileptic phenotype as well as cognitive, social, and motor alterations. Ex vivo biochemical analyses were performed to verify protein silencing and autophagy progression. Our findings revealed that loss of Tbc1d24 induces absence seizures that progressively increase over time. In parallel, behavioral tests show a hyperactive and anxious profile in Tbc1d24cKO mice. This new cKO mouse provide a robust pre-clinical in-vivo model to explore the autophagy process and the endo-lysosomal pH as potential therapeutic target for epilepsy.