New mouse models for tackling motor neuron disease and other neurodegenerative disorders.

This application is for a 4-year research project to create four new valuable mouse models in which to study neurodegeneration, with a long term view to finding therapeutics. These mouse strains complement and are different from existing models. During this award we will make the mice plus control strains, carry out initial ?clinical? analysis, and will make all the mice freely available to all other interested researchers.

Motor neuron diseases (MNDs) are relatively common (in UK 1 in 400 death certificates is issued for some form of MND) and can strike at any age ? spinal muscular atrophy is the biggest single genetic killer of children world-wide, whereas amyotrophic lateral sclerosis (ALS) is a disease of mid-life that has a lifetime risk of up to 1 in 600. These diseases progress inexorably to paralysis and death and we have no treatments that improve quality of life or lifespan of sufferers. MNDs have a genetic component but for ALS only one major effect causative gene, SOD1 has been found (in 1993) and we still have no idea why the mutant form of the protein kills neurons. Recently a protein called TDP43 was identified which aggregates abnormally in the nerve cells of people suffering from ALS and in 2008 rare families have been identified who succumb to ALS with death in mid-life, because they have mutations in the TDP43 gene. TDP43 protein abnormalities have also been found in frontotemporal dementia (the most common form of dementia after Alzheimer?s disease), and Parkinson?s disease, Pick?s disease and other forms of neurodegeneration.

Once a human mutant gene such as SOD1 or TDP43 has been identified, the next step is to genetically alter mice so that they recapitulate the human disease and we can study the pathological processes leading to illness and death. SOD1 transgenic mice have been tremendously helpful in understanding ALS, but have disadvantages. Currently no TDP43 mouse models exist. We want to create two new strains of mice, using newer technologies, which more closely model ALS in humans. These mice will be better for understanding human disease, for finding early ?biomarkers? of disease, and for trialling new therapies because they more closely replicate what is happening in humans. We will make the mice freely available to all researchers, without ties, by distributing them in the major mutant mouse repositories in Europe and USA for sending out to all research labs.

Amyotrophic lateral sclerosis (ALS) is mostly (~80%) sporadic but familial forms (FALS, ~20%) are known. The SOD1 gene is the most common causative gene for FALS, and recently rare mutations have been identified in the TDP43 gene. This is of interest because TDP43 is the major ubiquitinated protein in inclusions in both sporadic and familial ALS ? although not SOD1 related ALS.

We are requesting funding for one postdoc and one technician (minimum staffing to make this application realistic) to create two novel mouse strains modelling amyotrophic lateral sclerosis (ALS) with the SOD1 human genomic coding region knocked in, and two novel strains with a human TDP43 cDNA knocked in. These mouse strains are essential for understanding ALS because: if the knock in mice have a mid-life disease, this would arise from mutation, not from overexpression of the transgene array, which is known to have an effect in existing SOD1 transgenics; the model is physiologically more relevant than existing transgenics, giving us a better understanding of pathology and a better model for conventional and gene therapeutics ? including siRNA and lentiviruses; this model also gives us a better knowledge of the protein interactions that occur in ALS because it is biochemically more relevant to the human disease; this model helps address the biophysics/biochemistry of mutant:wildtype dimers and enzyme function, in a variety of primary cell lines, including embryonic stem cells and motor neurons; a mouse with late onset disease will direct us to biomarkers, desperately needed by ALS clinicians. Critically, we will make Cre-conditional knock in mice in which the mutation can be turned off in any tissues ? thus informing us, for example, about motor neuron ? glia interactions as we already know SOD1 induced motor neuron death is not cell autonomous and therefore glia and other cells may be targets for therapy. We wish to make knock in mice for both mutant SOD1 and TDP43, because although mutations in these genes may feed into a final common pathway, the lack of TDP43 pathology in SOD1 mutant ALS clearly shows the genes have different initial effects.

A critical feature of this award is that we will make the mice freely available immediately, via the European Mutant Mouse Archive and the Jackson Laboratory, for distribution to all interested laboratories.