MOLECULAR MECHANISMS UNDERLYING THE EPILEPTOGENESIS AND SEIZURE PROGRESSION IN TUBEROUS SCLEROSIS COMPLEX 1 DEFICIENT MOUSE MODELS

Molecular mechanisms involved in epileptogenesis in the developing brain remain poorly understood. We seek to understand four basic questions related to epileptogenesis: (1) What is the role of mTOR dysregulation in epileptogenesis in the developing brain? (2) What are the molecular mechanisms downstream of mTOR hyperactivation that trigger epileptogenesis in developing brains? (3) What are the rational, long-term pharmacological treatments to prevent the development or progression of seizures? (4) What are biomarkers for epileptogenesis and the prognostic biomarkers for disease progression? We have established a neuroglia tuberous sclerosis complex 1 (TSC1)-deficient mouse model in which spontaneous seizures begin at 2.5 months of the age and progress into 7-8 months. This time course allows the analysis of molecular changes before and after the onset of spontaneous electrographic and behavioral seizures and provides reliable biomarkers for epileptogenesis and the progression of epilepsy. We have also developed a neuronal-specific mouse model, deleting Tsc1 by driving cre from the CAMK2 promoter. We propose three specific aims, utilizing systems biology/gene expression profiling, electrophysiological, biochemical, immunohistochemical, and behavioral studies. Studies will use adolescent and adult mice before and after the onset of first electrographic evidence of hyperactivity and then after the onset of behavioral seizures. Specific Aim 1: Determine the effect of neuroglia TSC1 deletion on epileptogenesis and progress of seizures. This will test the hypothesis that TSC1 deletion in astrocytes and a subset of late-born forebrain pyramidal neurons underlie the behavioral and electrographic seizure phenotypes and progress of epilepsy. These findings will provide the time windows for trials of mTORC-1 inhibitor-dependent intervention. Specific Aim 2: Characterize the signaling pathways downstream of mTOR hyperactivation that are involved in epileptogenesis and seizure progression, using ribosome profiling technique. This will test the hypothesis that mTOR controls the translation of a specific repertoire of neuronal and astrocytic genes, which cooperatively regulate the initiation and progression of epilepsy. We will validate the molecular changes in both neuronal and neuroglia TSC1-deficent mouse brains. Specific Aim 3: Determine the effects of mTOR inhibitor on the initiation and progression of seizures and on the molecular changes that accompany the initiation and progression of seizures. This will test the efficacy of potential treatments with mTORC1 inhibitors and identify molecule players that respond to or do not respond to mTORC1 inhibitors. We will examine the effects of rapamycin on the molecular changes associated with the EEG/seizure activity, with a focus on the molecular signatures that are significantly changed during epileptogenesis in our model mice. Our studies will identify molecular mechanisms downstream mTOR signaling that underlie epileptogenesis in TS and other forms of epilepsies and determine potential therapeutic targets downstream of mTOR. This could impact treatment strategies for epileptogenesis and the progression of epilepsy.