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Updated: Jun 6, 2026
Shifting Zebrafish Lethal Skeletal Mutant Penetrance by Progeny Testing
Published on: September 1, 2017
tubb5 knockout in zebrafish causes neurodevelopmental defects via notch pathways
Huihui Liu1, Jinze Li1, Linglu Xiao1
1Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
Abstract:
Mutations in TUBB5 cause complex cortical dysplasia with other brain malformations. However, the pathogenic mechanisms underlying TUBB5 mutations remain incompletely understood. We generated tubb5 knockout zebrafish using CRISPR/Cas9 genome editing technology. Homozygous mutants were lethality within two weeks post-fertilization along with developmental delay, craniofacial malformations, uncoordinated movement and increased seizure susceptibility. tubb5 knockout larvae also showed reduced locomotor activity and impair photomotor responses. Furthermore, tubb5 knockout larvae exhibited significantly attenuated locomotor activity under alternating light/dark conditions compared to wild-type controls. Pharmacological intervention with carbamazepine and sodium valproate ameliorated both locomotor dysfunction and PTZ-induced seizure susceptibility in mutant larvae. Transcriptome analysis revealed that tubb5 knockout larvae showed upregulated expression of notch1a and her5, which inhibit neural progenitor differentiation. Whole-mount in situ hybridization demonstrated decreased neurogenin1 and huc positive neurons, while sox2 positive neurons were increased in tubb5 mutants, indicating disrupted neural progenitor differentiation. DAPT treatment rescued both developmental and locomotor deficits tubb5 knockout zebrafish. This study demonstrates that tubb5 regulates neural progenitor differentiation via the Notch signaling pathway and identifies DAPT as a potential therapeutic agent for disorders associated with human TUBB5 mutations.
Insights
Mutations in TUBB5 cause brain malformations. Zebrafish lacking TUBB5 showed developmental delays and seizures, but DAPT treatment improved these defects by regulating neural progenitor differentiation via the Notch pathway.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Mutations in TUBB5 are linked to complex cortical dysplasia and brain malformations.
- The precise pathogenic mechanisms of TUBB5 mutations are not fully understood.
Purpose of the Study:
- To investigate the function of TUBB5 in zebrafish development.
- To elucidate the molecular mechanisms underlying TUBB5-related brain malformations.
- To identify potential therapeutic strategies.
Main Methods:
- Generated tubb5 knockout zebrafish using CRISPR/Cas9 technology.
- Assessed developmental, behavioral, and seizure phenotypes in mutants.
- Performed transcriptome analysis and whole-mount in situ hybridization.
- Utilized pharmacological interventions (carbamazepine, sodium valproate, DAPT).
Main Results:
- Homozygous tubb5 knockout zebrafish exhibited lethality, developmental delay, craniofacial malformations, uncoordinated movement, and increased seizure susceptibility.
- Mutant larvae showed reduced locomotor activity and impaired photomotor responses.
- TUBB5 deficiency disrupted neural progenitor differentiation, indicated by altered gene expression (upregulated notch1a, her5; decreased neurogenin1, huc; increased sox2).
- Carbamazepine, sodium valproate, and DAPT treatments ameliorated mutant phenotypes.
Conclusions:
- TUBB5 plays a critical role in neural progenitor differentiation through the Notch signaling pathway.
- Disruption of TUBB5 function leads to significant developmental and neurological deficits.
- DAPT shows potential as a therapeutic agent for human TUBB5 mutation-related disorders.
