Find the target of valproic acid: pioneering the use of a non-animal model for basic biomedical (epilepsy) research

Aims

This project aims to build on previous NC3Rs-funded research to demonstrate the utility of an amoeba-based model to identify how valproic acid regulates PIP3 as a possible mechanism for its antiepileptic action.

Background

It has recently been shown with NC3Rs funding that a commonly used antiepileptic drug, valproic acid, blocks the turnover of phosphoinositides in a simple model organism, the amoeba Dictyostelium. It was subsequently demonstrated in the rat that seizures reduce hippocampal phosphatidylinositol trisphosphate (PIP3) and that this can be restored by valproic acid suggesting that the antiepileptic action of this drug may be exerted via PIP3 signalling. Many mechanisms for the activity of valproic acid have been proposed but an involvement in phosphoinositide signalling could explain a number of these. However, the detailed target of this effect is not known and while mechanistic studies in rats would require large numbers of animals the availability of the Dictyostelium model provides a viable alternative.

Research details and methods

This project will develop sensitive methods to analyse the effects of valproic acid on phosphoinositide turnover, and identify the specific enzyme targeted by valproic acid through use of gene knockouts and mutations. The project will expand the use of Dictyostelium as a model for study of phosphoinositides and epilepsy by heterologous expression of human proteins from this pathway. 

Epilepsy research generally employs a large number of rodents to use either as a source of neurons or to re-create seizures in moderate to severe experiments. The goals of these experiments are to identify how seizure treatments block seizures and to develop better treatments. We have recently shown that the most commonly used seizure control treatment, valproic acid, blocks the turnover of a specific family of chemicals (called phosphoinositides) in the simple nonanimal biomedical model, Dictyostelium. We subsequently found that valproic acid plays a similar role in the brain of rodents during seizures. Investigating how valproic acid acts in this role will require the use of hundreds of animal lives, and will involve a range of moderate to severe experiments. In this project, we will replace these animal experiments using Dictyostelium. In pursuit of this, we will develop a sensitive method to analyse the role of valproic acid in controlling phosphoinositides turnover, we will identify the specific enzyme targeted by valproic acid for this effect, and we will characterise the effect of valproic acid treatment on phosphoinositide regulation. We will also use this simple amoeba as a pioneering new system to produce human enzymes for research purposes, providing a long-term model for biomedical research into human protein function as an alternative approach to the rapidly expanding number of transgenic animals used in research.

• Blog: Improve cross-talk, fewer mouse models, and coconuts
• Blog: Dish and chips - NC3Rs at the British Science Festival 2015
• Engagement Activities: Talk Science at The British Library 2016
• Engagement Activities: Pint of Science 2016
• Further Funding: NC3Rs Strategic Grant, Developing a non-animal model system to investigate bitter tastants as new treatments for asthma, January 2015, £98,894
• Further Funding: NC3Rs Project Grant, Replacing, refining and reducing animal usage in epilepsy research using a non-sentient model, January 2010, £415,373