TORC1-Dependent Epilepsy Caused by Acute Biallelic Tsc1 Deletion in Adult Mice

Elisabeth Abs, Susanna Goorden, Jaga Schreiber, Iris Overwater, Marianne Hoogeveen - Westerveld, Caroline Bruinsma, Elvedin Aganovic, CH Zuiderveen Borgesius, Mark Nellist, Ype Elgersma

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Abstract

ObjectiveSeizure development in tuberous sclerosis complex (TSC) correlates with the presence of specific lesions called cortical tubers. Moreover, heterozygous TSC animal models do not show gross brain pathology and are seizure-free, suggesting that such pathology is a prerequisite for the development of epilepsy. However, cells within TSC lesions show increased activity of the target of rapamycin complex 1 (TORC1) pathway, and recent studies have implicated this pathway in non-TSC-related animal models of epilepsy and neuronal excitability. These findings imply a direct role for TORC1 in epilepsy. Here, we investigate the effect of increased TORC1 signaling induced by acute biallelic deletion of Tsc1 in healthy adult mice. MethodsBiallelic Tsc1 gene deletion was induced in adult Tsc1 heterozygous and wild-type mice. Seizures were monitored by electroencephalographic and video recordings. Molecular and cellular changes were investigated by Western blot analysis, immunohistochemistry, and electrophysiology. ResultsMice developed epilepsy a few days after biallelic Tsc1 deletion. Acute gene deletion was not accompanied by any obvious histological changes, but resulted in activation of the TORC1 pathway, enhanced neuronal excitability, and a decreased threshold for protein-synthesis-dependent long-term potentiation preceding the onset of seizures. Rapamycin treatment after seizure onset reduced TORC1 activity and fully abolished the seizures. InterpretationOur data indicate a direct role for TORC1 signaling in epilepsy development, even in the absence of major brain pathology. This suggests that TORC1 is a promising target for treating seizures not only in TSC but also in other forms of epilepsy that result from increased TORC1 activation. Ann Neurol 2013;74:569-579
Original languageUndefined/Unknown
Pages (from-to)569-579
Number of pages11
JournalAnnals of Neurology
Volume74
Issue number4
DOIs
Publication statusPublished - 2013

Research programs

  • EMC MGC-02-96-01
  • EMC ONWAR-01-94-01

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