Epilepsy is a disabling and costly disease that affects ~1% of the general population, requires long-term treatment and reduces productivity. For over 70% of patients, however, the underlying cause of epilepsy remains unknown, impeding effective diagnosis and treatment. Most forms of epilepsy have an underlying genetic basis;this ranges from single genes in Mendelian disorders, to multiple genes and environmental factors that collectively contribute to multifactorial "complex" epilepsy syndromes. Many genes involved in Mendelian epilepsy syndromes are known-the vast majority are autosomal dominant-however, autosomal dominant epilepsy genes do not significantly contribute to epilepsy in the general population. In contrast, the role of autosomal recessive epilepsy genes in complex epilepsy remains largely unexplored. There is a critical need to explore the role of identified autosomal recessive epilepsy syndrome genes in epileptogenic pathways, and to comprehensively characterize their pathophysiology in order to develop new therapeutic approaches. Our long-range goal is to define pathophysiologic mechanisms underlying human epilepsy and thereby improve the diagnosis and treatment of epilepsy. This proposal is built on our preliminary data and published reports demonstrating that 1) mutations in the PRICKLE genes cause epilepsy, 2) PRICKLE1 and the related PRICKLE2 protein play important roles in WNT-mediated signaling, which is implicated in critical biological processes such as neurodegeneration and neurodevelopment, and 3) the PRICKLE1 protein influences the normal function of REST, a critical repressor of neural genes. We hypothesize that mutations in PRICKLE genes can cause human epilepsy by perturbing PRICKLE function.
The specific aims of this proposal are: 1) to screen a cohort of epilepsy patients for PRICKLE1 and PRICKLE2 variants to evaluate their role in complex epilepsy;2) to define the functional effect of PRICKLE mutations on WNT-mediated signaling, REST-mediated transcriptional repression, and neurite extension in vitro;3) to use zebrafish to define the functional effect of PRICKLE mutations in vivo, and;4) to define the importance of PRICKLE mutations in vivo by assessing mice with mutations in the Prickle genes. The experimental design and methods to accomplish the first aim include direct sequencing and quantative PCR of the PRICKLE genes in a well-characterized cohort of patients with epilepsy and in a large control population.
The second aim will involve cloning of mutant PRICKLE genes, gene silencing using PRICKLE-specific siRNA, and co-expressing PRICKLE binding partners by transient transfection to examine how PRICKLE mutations affect function.
The third aim will use the zebrafish model to characterize human PRICKLE mutations.
The fourth aim will use electroencephalography and histology to characterize electrophysiology and brain pathology in mice with Prickle mutations. Taken together, these assays will provide insights into how the PRICKLE gene functions are disrupted in human epilepsy.

Public Health Relevance

Relevant to Public Health Epilepsy is a disabling disease that affects ~1% of the general population and requires long-term treatment. Most forms of epilepsy are inheritable, but for over 70% of patients, the underlying genetic basis for their condition remains unknown, impeding effective diagnosis and treatment. To develop new ways to diagnose and treat epilepsy, we aim to identify gene mutations not yet known to be involved, and to explore how these mutations can cause the disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS064159-04
Application #
8298540
Study Section
Molecular Neurogenetics Study Section (MNG)
Program Officer
Whittemore, Vicky R
Project Start
2009-09-01
Project End
2014-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
4
Fiscal Year
2012
Total Cost
$321,563
Indirect Cost
$107,188
Name
University of Iowa
Department
Pediatrics
Type
Schools of Medicine
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Mei, Xue; Westfall, Trudi A; Zhang, Qihong et al. (2014) Functional characterization of Prickle2 and BBS7 identify overlapping phenotypes yet distinct mechanisms. Dev Biol 392:245-55
Yin, Terry C; Britt, Jeremiah K; De Jesús-Cortés, Héctor et al. (2014) P7C3 neuroprotective chemicals block axonal degeneration and preserve function after traumatic brain injury. Cell Rep 8:1731-40
Yang, Tian; Jia, Zhonglin; Bryant-Pike, Whitney et al. (2014) Analysis of PRICKLE1 in human cleft palate and mouse development demonstrates rare and common variants involved in human malformations. Mol Genet Genomic Med 2:138-51
Yang, Tian; Bassuk, Alexander G; Stricker, Sigmar et al. (2014) Prickle1 is necessary for the caudal migration of murine facial branchiomotor neurons. Cell Tissue Res 357:549-61
Mei, Xue; Wu, Shu; Bassuk, Alexander G et al. (2013) Mechanisms of prickle1a function in zebrafish epilepsy and retinal neurogenesis. Dis Model Mech 6:679-88
Darbro, Benjamin W; Mahajan, Vinit B; Gakhar, Lokesh et al. (2013) Mutations in extracellular matrix genes NID1 and LAMC1 cause autosomal dominant Dandy-Walker malformation and occipital cephaloceles. Hum Mutat 34:1075-9
Yang, Tian; Bassuk, Alexander G; Fritzsch, Bernd (2013) Prickle1 stunts limb growth through alteration of cell polarity and gene expression. Dev Dyn 242:1293-306
Sowers, L P; Loo, L; Wu, Y et al. (2013) Disruption of the non-canonical Wnt gene PRICKLE2 leads to autism-like behaviors with evidence for hippocampal synaptic dysfunction. Mol Psychiatry 18:1077-89
Cherepanova, Natalya S; Leslie, Elizabeth; Ferguson, Polly J et al. (2013) Presence of epilepsy-associated variants in large exome databases. J Neurogenet 27:1-4
Tao, Hirotaka; Inoue, Ken-ichi; Kiyonari, Hiroshi et al. (2012) Nuclear localization of Prickle2 is required to establish cell polarity during early mouse embryogenesis. Dev Biol 364:138-48

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