Epilepsies affect about 3 million people in the US and 70 million in the world. In Greater Los Angeles area there are 8,500 Veterans with epilepsy. The VA healthcare system is challenged by 300,000 to 400,000 USA soldiers returning from OEF/OIF;212,000 service members suffering traumatic brain injury (TBI) over the last decade;and some 9,600 Veterans are already under treatment for post-traumatic epilepsy (PTE). The specific role of heritable epilepsies in PTE remains unresolved. Amongst the heritable epilepsies, Juvenile Myoclonic Epilepsy (JME) is the most common and there is no cure. To find a cure, we have been expanding the JME genome, increasing our understanding of the functions of myoclonin1/EFHC1, a JME causing gene, and defining new putative major JME gene(s) by next generation sequencing. Now propose to continue studying the myoclonin1/EFHC1 disease mechanisms of persisting grand mal and myoclonic seizures in JME. We will also study how important new putative epilepsy genes are in clinic based and Veterans cohort. If a putative epilepsy gene is in at least 3% of our cohorts, we seek proof for causality by replication of epilepsy in knockout (Ko) or knockin (Ki) mice model. The results guide which putative epilepsy genes have priority for studies of functions and disease mechanisms in Drosophila melanogaster (Aim 3), mice (Aim 2) and humans (Aim 1).
Specific Aim 1 involves human mutation analysis of JME genes and asks: Are mutations in Myoclonin1/EFHC1 population specific? (Aim 1a) Screen for new mutations in myoclonin1/EFHC1 in 442 recruited/available human JME index cases (65 from Peru, 120 from Brazil, 137 from LA, and 100 Veterans in LA) and 1,000 controls and confirm the two stages of epilepsy development: (a) susceptibility/epileptogenicity, and (b) established epileptogenesis. [Note: Human material is available from our complementary NIH grant and this project will only recruit/enroll Veterans.] (Aim1b) Screen for mutations in new putative JME genes being identified by the epilepsy deep sequencing pipeline (our complementary NIH grant).
Specific Aim 2 proves causality by knockout of JME gene in mice.
(Aim 2 a) Conduct neuropathological analysis of the striatum-nigro-thalamic-cortical and pedunculopontine pathway system, and compare neuropathology of caudate, putamen, globus pallidus, thalamus substantia nigra and brainstem especially superior coliculus and dorsal pons varolii of Myoclonin1/efhc1 KO mice with myoclonias only versus Myoclonin1/efhc1 KO mice with grand mal seizures.
(Aim 2 b) Develop a KO mouse of new putative JME genes that satisfy the screening process of the epilepsy deep sequencing pipeline.
Specific Aim 3 studies the Drosophila model.
(Aim 3 a) Analyze in vivo how pathological mutations impact Drosophila EFHC1 protein (Defhc1.1) role in synaptic and dendritic development.
(Aim 3 b) Characterize Defhc1.2 mutant as well as the double Defhc1.1/Defhc1.2 mutant.
(Aim 3 c) Dissect Defhc1.1 by deletion analysis to identify the portion of the protein that binds to microtubules, and confirm that it is also the same binding sit in Defhc1.2.
(Aim 3 d) Because EFHC1 proteins bind microtubules through a non-canonical microtubule binding domain, a 'pilot experiment'will determine the structure of the protein by crystallography.
(Aim 3 e) Exploit the Drosophila model and gain functional information on the new putative JME genes being identified through the epilepsy deep sequencing pipeline. Finally, until recently, common genetic epilepsies were thought to be 'ion channelopathies'. Now, we provide more proof that JME is due to mutations in developmental genes, like Myoclonin1/EFHC1, involved in cell division, apoptosis, neuroblast migration, and synapse and dendrite growth. Understanding JME disease mechanisms brings an era of targeted and designer medicine, and positively impacts the mission of the VA healthcare system and the health of Veterans.
The ultimate purpose of this project is to lessen the epilepsy burden among Veterans in the VA healthcare system. By studying the functions of mutated gene(s) for Juvenile Myoclonic Epilepsy (JME) defined by an epilepsy deep sequencing pipeline and proving causality, we can better determine the clinical and public health importance of new putative epilepsy genes and screen for their mutations in Veterans epilepsy clinics. Understanding the disease mechanisms of JME and providing JME mice models of human epilepsy for testing and developing new antiepileptic drugs will bring about an era of truly targeted and designer medicine against JME. This will lead to novel antiepileptic drugs that work against both idiopathic generalized and symptomatic epilepsies;and thus lessen the epilepsy burden in the VA healthcare system.