Genetic Epilepsy Models in Zebrafish

Informations projet

GEMZ

N° de convention de subvention: 798703

DOI

10.3030/798703

Projet clôturé

Date de signature de la CE 19 Mars 2018

Date de début 1 Janvier 2019

Date de fin 31 Decembre 2020

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 196 400,40

Contribution de l’UE

€ 196 400,40

Coordonné par

UNIVERSITETET I OSLO
Norway

Periodic Reporting for period 1 - GEMZ (Genetic Epilepsy Models in Zebrafish)

Période du rapport: 2019-01-01 au 2020-12-31

Résumé du contexte et des objectifs généraux du projet

Epilepsy is a common, severe neurological disorder, marked by abnormal synchronous activity in the brain (seizures), typically characterized by either a sudden brief period of altered or lost consciousness, involuntary movements or convulsions. Epilepsy affects about 65 million people worldwide, with approximately 30% of patients currently resistant to available medication. Within the last two decades, a tremendous increase in our knowledge and understanding of the molecular mechanisms underlying epilepsies has been achieved. The discovery of highly penetrant single gene mutations in rare monogenic forms of epilepsies and the common genetic risk factors in prevalent forms of epilepsies have served as key findings in accelerating the progress in this research field. Nevertheless, the majority of genetic factors is still unknown and important questions as to how these identified genetic defects exactly lead to epileptic seizures and how such epileptogenic mechanisms interact with brain development remain largely unanswered. Thus, there is an urgent need for the rapid functional evaluation of candidate genes. Taking this into account, the overall objective of the project was to generate novel genetic epilepsy models in zebrafish and elucidate the molecular mechanisms underlying epileptogenesis during early brain development, by identifying the signalling pathways activated as a result of selected genetic mutations. In conclusion, the obtained data contributes significantly to the state of the art with regard to early childhood epilepsies and provides new in vivo scientific knowledge about pathogenetic mechanisms related to the mutations of interest.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

To fulfill the scientific objectives of the project, three new zebrafish models of epilepsy were generated (namely, models for nexmifaa-/-, scn1lab-/- and scn1lab overexpression (hereafter called scn1lab-OE)). For all mutants, EEG and behavioural analysis were conducted. The qRT-PCR analysis was carried out to profile gene marker expression in mutants. For scn1lab-/-, we identified the signaling pathways activated as a result of mutation and determined how these pathways are modified as brain development progresses. Our findings have high scientific value as we have provided for the first time, novel insights into the early mechanisms of Dravet syndrome pathogenesis and also presented first-time, evidence for potential disease modification by fenfluramine. Overall, we have also indicated functional evidence for a thermosensitive seizure-promoting effect of scn1lab-OE, thus mimicking SCN1A gain of function in human patients. In the case of the nexmifa-/- model, experiments are still ongoing. However, once published, our nexmifaa deficiency model will be the first published animal model of NEXMIF-related epilepsy.
The data obtained within the project were shown, among others at the following conferences: 1) American Epilepsy Society Meeting 2019, Baltimore, USA, 4th Zebrafish Workshop, University of Wrocław, Poland; 14.02.2019 Polish Zebrafish Society virtual meeting, Poland, 23.10.2020 and Brain Awarness Week, Lublin, Poland, 17.03.2021. Altogether, six original papers, one review paper and one popular press paper were published.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The successful management of childhood epilepsies is challenging due to a high pharmacoresistance (ca. 30%), limited number of therapeutic options or associated comorbidities (e.g. memory impairments, autistic behaviour, anxiety etc.). The severity of epilepsy is directly proportional to the direct costs for management of the disease. This also impacts social relationships, such as a higher divorce rate between parents of children with epilepsy, demanding extensive psychological and clinical assistance. Additionally, epilepsy substantially affects the economy directly (i.e. costs of drugs, hospitalizations, psychiatric and/or psychological support, diagnostic tests performed, brain MRI, sick leave for both parents and patients etc.) or indirectly through unemployment or part-time work among people with epilepsy, (ranging between 50 to 100% in developed and developing countries, respectively). However, in cases of children with epilepsy, indirect costs are higher, because parents often need to take care of the child temporarily or permanently, instead of engaging in a full-time job.
In summary, epilepsy imposes a substantial economic burden for healthcare systems in addition to being a tremendous social burden for individuals and their families. Unfortunately, in many parts of the world, epilepsy patients and their families still suffer from stigmatization and discrimination. The MFC project may not only aid in bringing effective treatments closer to the clinic but also raise public awareness regarding disease causation, thus potentially lessening overall social stigma and prejudice. The data obtained from this project has also contributed significantly to the basic knowledge regarding mechanisms of epileptogenesis related to specific types of mutations. The results should open new avenues for other scientists towards successful identification of new drug leads. In terms of long-term perspectives, new and effective therapeutic options may increase the productivity of children when they reach adulthood and allow parents to continue their professional careers. It will also decrease direct (e.g. lower number of hospitalizations) and indirect costs (e.g. psychological support) for management of the disease. The potential users of our findings include researchers, clinicians, families with sick children, and pharmaceutical companies.

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