Authors :
Presenting Author: Zachary Stayn, BA – Boston Children's Hospital
Mark LaCoursiere, MS – Boston Children's Hospital
Parul Chaudhary, MBBS, PhD – Boston Children's Hospital
Annapurna Poduri, MD, MPH – Boston Children's Hospital
Rationale:
We sought to characterize the genetic basis of early-onset epilepsy by studying the CAMSAP3 gene. Recently observed with early onset epilepsy in a sequencing study, this gene has been shown to be responsible for microtubule growth and organization in vitro, but there is no in vivo evidence supporting the role of CAMSAP3 in the pathophysiology of human epilepsy.Methods:
We used CRISPR/Cas9 gene editing to generate a zebrafish knockout model in order to model Camsap3 complete and partial loss of function. We performed detailed phenotypic assessments of mutant vs. wild-type control zebrafish larvae, including using behavioral analysis to assess for seizure presentation, electrophysiology (local field potential [LFP] recording) to assess for abnormal synchronous neuronal firing, and immunohistochemistry to evaluate for cellular and anatomic abnormalities.Results:
Camsap3 knockout (crispant) fish exhibited significant neuronal hyperexcitability manifested as frequent bursts and spikes within bursts on LFP recordings, as well as reduced numbers of inhibitory interneurons in the tectum. We also found evidence of increased acetylation of alpha-tubulin, neuronal cell death, and general microtubule disorganization throughout the zebrafish central nervous system. Despite these abnormalities in the zebrafish, we did not observe seizure-like swim patterns in the crispants.Conclusions:
Our zebrafish Campsap3 crispant models demonstrate hyperexcitability and reduced interneuron number, both of which, we hypothesize, lead to central nervous system inhibition due to abnormal developmental processes. We thus provide evidence supporting the role of CAMSAP3 in the development of epilepsy. Further studies are needed to understand why no seizures were observed in the mutants and how the effects of Camsap3 dysfunction might be treatable.Funding:
This work was supported by the AES BRIDGE Summer Research Internship Grant.