# The Circadian Molecular Clock is a Biomarker for Epilepsy in Focal Cortical Dysplasia

> **NIH NIH R01** · BROWN UNIVERSITY · 2021 · $81,362

## Abstract

PROJECT SUMMARY
The parent R01 is based on our study of medically refractory pediatric epilepsy, where we identified decreased
mRNA levels of the transcription factor, Circadian Locomotor Output Cycles Kaput (Clock), compared with non-
epileptic brain. Mice with targeted deletion of the Clock gene in excitatory neurons have spontaneous seizures,
leading us to hypothesize that loss of Clock leads to circuit dysfunction and epilepsy. In both the parent R01
and the proposed new experiments, we study pediatric epilepsy. In this supplement, we investigate a rare,
newly diagnosed form of genetic infantile epilepsy and developmental delay caused by mutations in SLC13A5,
a sodium-coupled citrate transporter, using models that we already have in the laboratory, and using the same
techniques that we are using in the parent grant i.e. video EEG and whole cell patch-clamp electrophysiology
in hippocampal neurons. Slc13a5 mutations result in decreased intracellular citrate levels, indicating metabolic
defect. Since we have extended our parent studies of Clock gene into metabolomics, the proposed studies are
in keeping with the scope and overall hypothesis that metabolic defects underlie circuit dysfunction in
epilepsy. Analysis of Slc13a5 as a less complex, single gene disorder will help us understand important links
between metabolic signatures and epilepsy. We generated mouse models containing two of the most
commonly found Slc13a5 missense mutations in pediatric patients. Preliminary characterization revealed an
unexpected gain-of-function effect of a sodium-binding domain missense mutation i.e. more severe seizures,
meeting the definition of status epilepticus, in striking contrast to Slc13a5 gene ablation, which does not
produce seizures, indicating altered gene function. We hypothesize that aberrant cortical and hippocampal
activity arises from altered neurotransmitter levels and electrophysiological properties at excitatory and
inhibitory synapses. We will test our hypothesis in two Aims. In Aim 1, we will investigate changes in epilepsy
associated with Slc13a5 mutations in comparison with Slc13a5 ablation. Using video electroencephalogram
(EEG), we plan to measure seizure thresholds in these mice, interictal epileptiform abnormalities, epilepsy
severity, and baseline EEG patterns. In Aim 2, we will determine neurotransmitter changes associated with
Slc13a5 mutations, and identify, by patch-clamp electrophysiology, how altered citrate or TCA cycle
intermediates lead to depletion of glutamate and GABA levels. We will also investigate action potential
generation threshold, firing patterns, and membrane properties to determine changes in excitatory-inhibitory
balance. Analysis of hetero- and homozygous mouse null and missense mutants would help determine how
the mutant allele gains function or interferes with normal gene activity. These studies constitute a major part of
a thesis project for our URM graduate student, whose multi-disciplinary training plan...

## Key facts

- **NIH application ID:** 10302615
- **Project number:** 3R01NS104428-03S1
- **Recipient organization:** BROWN UNIVERSITY
- **Principal Investigator:** Judy Shih-Hwa Liu
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $81,362
- **Award type:** 3
- **Project period:** 2019-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10302615

## Citation

> US National Institutes of Health, RePORTER application 10302615, The Circadian Molecular Clock is a Biomarker for Epilepsy in Focal Cortical Dysplasia (3R01NS104428-03S1). Retrieved via AI Analytics 2026-06-15 from https://api.ai-analytics.org/grant/nih/10302615. Licensed CC0.

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