Functional and genomic analyses of novel epilepsy mutations

Lead Research Organisation: University of Liverpool
Department Name: Institute of Translational Medicine


Genetics has long been recognised to play an important role in many types of epilepsy. However, it is only in the last few years that substantial progress has been made in identifying the actual genetic variations that cause epilepsy. Although this is a major recent breakthrough, understanding how these genetic variations contribute to epilepsy and translating this into new treatments will require extensive further work. This multi-disciplinary project will begin to address these issues by focusing on the STXBP1 gene, which a major international scientific consortium has recently reported to be the second most commonly mutated gene in catastrophic infantile epilepsies. The principal aims of our research are to test how mutations in STXBP1 change the function of individual cells and the behaviour of animals that carry those mutations and to search for genetic pathways that can help to restore normal function and behaviour. This project will reveal how genetic variations in STXBP1 cause changes in the brain that lead to epilepsy. It may also suggest new therapeutic approaches for the treatment of catastrophic infantile epilepsies and perhaps more common forms of epilepsy.

Technical Summary

The identification of genetic variants associated with epilepsy over recent years represents a major breakthrough. However, we now need to understand how mutations in the identified genes contribute to epilepsy and to translate this into potential therapies. This project will address these issues by focusing on STXBP1 - the second most commonly mutated gene in catastrophic infantile epilepsies. Our principal aims are to characterise the functional effects of disease-causing mutations in STXBP1 and to search for genetic modifiers that can ameliorate the consequences of those mutations. This will involve using CRISPR to replace the single copy of the orthologous Caenorhabditis elegans unc-18 gene with wild-type and epilepsy-associated mutant human STXBP1. These humanised animal models will be analysed for alterations in neurotransmission and behaviour, and for genetic suppressor screening. Biochemical interactions of the corresponding human recombinant proteins with functionally important synaptic protein binding partners will be analysed in vitro. Overall, this multi-disciplinary project will illuminate how genetic variation in STXBP1 causes functional changes that lead to epilepsy and may reveal compensatory cellular pathways that could represent novel targets for antiepileptic drug discovery

Planned Impact

Discoveries from the project may suggest candidate drug targets for antiepileptic therapies, and so would be of interest to patients, clinicians and society as a whole. Given that epilepsy affects around 1% of the population and that approximately one third of patients are not responsive to current medication, new therapeutic approaches are sorely needed. Our focus on genetic screening for cellular pathways that can ameliorate the effects of genetic epilepsies could identify pathways that are amenable to modulation by existing clinically approved drugs. If so, this would obviate the need for toxicity testing and so enable potential rapid adoption for new indications in epilepsy patients within a few years. Alternatively, druggable targets within the identified pathways may interest commercial pharmaceutical enterprises aiming to discover lead compounds for novel anti-epileptic drug discovery, and so contribute to wealth generation.

This project will require the appointment of a post-doctoral research assistant to perform the bulk of the experimental work. This individual will receive extensive and high quality training in a variety of biochemical, molecular biological and genetic techniques relevant to many types of projects using a key model organism. In addition to laboratory training the post-doctoral researcher will also be expected to extend their transferrable skills base through involvement in the communication of scientific data generated from the project both in the form of written journal articles and audio-visual presentations at scientific meetings. Participation in University training modules in a range of transferable skills will also be required. The development of a highly trained and skilled scientist through these channels will benefit the individual but also contribute more broadly through skill transfer as the person moves on to other posts in the academic or commercial sectors.

The University of Liverpool runs several open days each year which are attended by large numbers of the general public. We participate in these events which showcase our research and provide hands on experience of scientific research for the lay-person. These activities will further impact on the post-doctoral researcher as we will expect participation in such events so as to develop skills necessary for presenting complex scientific information to a lay-audience. Related to these activities, we participate in a scheme which provides A-level students the opportunity to complete a 4-week research project in our laboratory. We will offer one such project in each year of the grant. An obvious consequence of these activities in the short term is the engagement of young people with science at an early stage of their academic careers such that they may eventually continue along this path in more advanced studies.

We are actively engaged though the University Press office in publicising the outcomes of our research to the public in the UK and worldwide. For example, a press release on our paper developing a novel C. elegans model of human neurodegenerative disease published in 2014 in Human Molecular Genetics resulted in widespread attention in the internet was the subject of a feature article in the US magazine The Scientist.


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Title Humanized nematode worms 
Description The CRISPR/Cas9 method was used to introduce a null mutation into the unc-18 gene (the C. elegans orthologue of STXBP1), thereby creating a paralyzed worm strain. We subsequently rescued this strain with transgenes encoding the human STXBP1/Munc18-1 protein (wild-type and eight different epilepsy-associated missense variants). This research method and the worm strains we created can be used to establish the pathogenicity of human STXBP1 gene variants and can also be used for drug discovery. 
Type Of Material Model of mechanisms or symptoms - non-mammalian in vivo 
Year Produced 2020 
Provided To Others? Yes  
Impact The humanized worm strains we created were analyzed via behavioral, electrophysiological, and biochemical approaches. This revealed that all 8 missense variants were pathogenic and resulted in decreased STXBP1/Munc18-1 protein stability, thereby explaining the underlying molecular defects that give rise to epilepsy.