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Updated: Feb 21, 2026
Behavioral And Physiological Analysis In A Zebrafish Model Of Epilepsy
Published on: October 19, 2021
Knockout of the epilepsy gene Depdc5 in mice causes severe embryonic dysmorphology with hyperactivity of mTORC1
James Hughes1,2, Ruby Dawson1,2, Melinda Tea3
1School of Biological Sciences, University of Adelaide, Adelaide, SA, AUS 5005, Australia.
Abstract:
DEPDC5 mutations have recently been shown to cause epilepsy in humans. Evidence from in vitro studies has implicated DEPDC5 as a negative regulator of mTORC1 during amino acid insufficiency as part of the GATOR1 complex. To investigate the role of DEPDC5 in vivo we generated a null mouse model using targeted CRISPR mutagenesis. Depdc5 homozygotes display severe phenotypic defects between 12.5-15.5 dpc, including hypotrophy, anaemia, oedema, and cranial dysmorphology as well as blood and lymphatic vascular defects. mTORC1 hyperactivity was observed in the brain of knockout embryos and in fibroblasts and neurospheres isolated from knockout embryos and cultured in nutrient deprived conditions. Heterozygous mice appeared to be normal and we found no evidence of increased susceptibility to seizures or tumorigenesis. Together, these data support mTORC1 hyperactivation as the likely pathogenic mechanism that underpins DEPDC5 loss of function in humans and highlights the potential utility of mTORC1 inhibitors in the treatment of DEPDC5-associated epilepsy.
Insights
DEPDC5 mutations cause epilepsy by disrupting mTORC1 regulation. In vivo studies confirm mTORC1 hyperactivity in Depdc5 knockout mice, suggesting mTORC1 inhibitors may treat DEPDC5-associated epilepsy.
Area of Science:
- Genetics and Molecular Biology
- Developmental Biology
- Neurology
Background:
- Mutations in DEPDC5 are linked to human epilepsy.
- In vitro studies suggest DEPDC5 negatively regulates mTORC1, a key cellular pathway.
- DEPDC5 functions within the GATOR1 complex during nutrient sensing.
Purpose of the Study:
- To investigate the in vivo function of DEPDC5.
- To elucidate the role of DEPDC5 in mTORC1 regulation and associated pathologies.
- To establish a DEPDC5 null mouse model for further study.
Main Methods:
- CRISPR-Cas9 mutagenesis was used to generate a DEPDC5 null mouse model.
- Phenotypic analysis of homozygous and heterozygous knockout embryos was performed.
- mTORC1 activity was assessed in knockout tissues and cells under nutrient-deprived conditions.
Main Results:
- Depdc5 homozygous null embryos exhibited severe developmental defects, including hypotrophy, anemia, edema, and vascular abnormalities.
- mTORC1 hyperactivity was confirmed in the brains and cells of knockout embryos.
- Heterozygous mice showed no overt phenotype, seizures, or increased tumor susceptibility.
Conclusions:
- DEPDC5 loss of function leads to mTORC1 hyperactivation, supporting its role as a negative regulator.
- These findings provide in vivo evidence for the pathogenic mechanism of DEPDC5 mutations in human epilepsy.
- mTORC1 inhibitors represent a potential therapeutic strategy for DEPDC5-related epilepsy.
