Investigating neuronal RNA localisation and translational deficits as gain of function mechanisms in ALS.

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Motor neurons are the nerves that send signals from the spinal cord to our muscles. They are amongst the largest nerve cells in the body and are highly specialized, in that their cell body is located in the spinal cord and its fiber (called 'axon') projects outside to the muscles. Amyotrophic Lateral Sclerosis (ALS) is a relentless and incurable disease that can kill the motor neurons, resulting in progressive paralysis and death within 5 years of diagnosis. ALS has a lifetime risk in UK of 1 in 250 in the UK population.Every cell in our body contains DNA, RNA and proteins. DNA is in the nucleus of cells and carries the information on how to build the proteins. Proteins are the building block of our cells and they can also perform important tasks for the cell's functions. RNA is the intermediate and carries the instructions for making individual proteins from the DNA, to the various locations inside a cell where these proteins are made and needed for specific jobs. Relatively recently it has become clear that axons, the long projections from individual neurons, need proteins to be made throughout their length, including at the very end most distant from the cell body. We do not yet know why this is, but certainly the need to respond quickly to local injury of an axon at a distant site, is one good reason why proteins need to be made in a localized region of a neuron, along the axon. To have the capacity to be able to make proteins where they are needed, neurons have to transport RNA around the cell, especially along the axon. Motor neurons are some of the largest cells in the body and have tremendously long axons, in humans one single axon can extend from the spinal cord out to our feet, often for over 1 meter in length. So in these cells particularly, the movement of RNA, and the local production of proteins is extremely important.Unfortunately, currently, we do not know which RNAs are moved around motor neurons and nor do we know which proteins can be made as a result. Our lack of knowledge has been largely because of the shear technical difficulty of analyzing RNA and protein in the separate cell bodies and axons. But this knowledge is critical to understanding ALS, because it turns out that proteins that bind and transport RNA in motor neurons, including a protein called FUS, can be mutated in ALS. So to understand ALS, we need to know what happens to FUS and the RNA it binds and the proteins that it makes, in health and in ALS, in different regions of motor neurons.Here, we tackle the technical problems of looking at RNA and protein in different regions of motor neurons, including the very important axon, by combining new molecular biology and microscope techniques, with novel mouse model we have made, in an innovative approach to find out what RNA and proteins are present in different regions within motor neurons. We will look over time, at presymptomatic animals, and at animals with ALS, so that we can see the healthy state as mice age, and the progressive disease state. We can then validate our results in samples taken from human ALS patients. We badly need this information to understand the mechanisms and pathology of ALS and to develop effective therapeutics for motor neuron disorders.