Investigating the role of the cell’s waste disposal systems in TDP-linked MND

In April 2016, Dr Jackie Mitchell gave a talk at the Regional Conference in Gatwick to explain the aims of her three year MND Association funded research project. We have now received her second year report. In this blog we explain a little bit more about what she’s been doing. She has already made some good progress.

A little bit of background
One known genetic cause of MND is a defect in the TARDBP gene, which makes the protein TDP-43, that can be found in the nucleus of a healthy cell. The nucleus is the part of the cell that contains all our DNA. Healthy cells also have two major ‘waste disposal systems’ which break down and remove unwanted proteins from cells. More information on the role of TDP-43 in MND can be found on our blog. Continue reading

Exploring the interaction between TDP-43 and RNA

In light of the upcoming Biomedical Research Advisory Panel meeting happening on Friday 7 April that will discuss which new research projects the MND Association will fund, we are pleased to report on the progress of one of our already-funded researchers. In their three year project, funded by the MND Association, Prof Annalisa Pastore (King’s College London) and Prof Gian Tartaglia (University Pompeu Fabra, Barcelona) are investigating the process by which TDP-43 binds to RNA. Below is a summary of the progress they made during their first year.

Background to the project

Alumni Board Meeting 2008

Annalisa Pastore, King’s College London

One of the causes of amyotrophic lateral sclerosis (ALS), the most common type of motor neurone disease (MND), is related to faulty functioning of the TDP-43 protein, a component that is naturally present in all of our cells. In healthy cells, TDP-43 resides in the centre of a cell (the nucleus) where it attaches to RNA and supports correct gene expression – that is, it helps to extract information carried by a gene to form proteins, the main building blocks of our bodies.

Continue reading

Using stem cell technology to understand more about how MND and FTD develop

The MND Association are funding Prof Kevin Talbot, Dr Ruxandra Dafinca (née Mutihac) and colleagues at the University of Oxford, who are investigating the link between the C9orf72 and TDP-43 genes in MND. We wrote about this research earlier in the year. As we’ve recently received their first year progress report we wanted to give you an update on what they’ve achieved. Continue reading

Transforming skin cells into nerve cells to understand MND gene mutations

In previous research Prof Kevin Talbot and colleagues at the University of Oxford began to understand more about how the C9orf72 gene defect causes human motor neurones to die. These studies were carried out using an impressive piece of lab technology, called induced pluripotent stem cell (iPSC) technology.

iPSC technology allows skin cells to be reprogrammed into stem cells, which are then directed to develop into motor neurones. Because they originated from people with MND, the newly created motor neurones will also be affected by the disease. Researchers can grow and study these cells in a dish in the laboratory. Continue reading

Developing a drug screen using nerve cells from a mouse model of MND

In a previous research project funded by the MND Association, Prof Kevin Talbot and colleagues from the University of Oxford developed a new TDP-43 mouse model of MND. Compared to other mouse models of MND, this one accurately reflects the symptoms of the disease and levels of the TDP-43 protein as seen in humans.

TDP43 location in the cell

Location of TDP-43 protein (shown in red) in healthy nerve cells, and how it moves into different parts of the cell in MND

This model of MND also shows how the TDP-43 protein becomes displaced from the nucleus (command centre of the cell) out into the cell cytoplasm, which makes up the cell body. Once TDP-43 has moved to the cytoplasm it is very difficult to shift, as it forms protein aggregates or clumps. It is thought that these clumps contribute to motor neurone cell death.

Prof Talbot’s latest project, together with researcher Dr David Gordon, is using cultured nerve cells from this new mouse model to screen a large library of drugs (our project reference: 831-791).

In the next two years, they will create an automated computerised imaging system that can detect the TDP-43 protein within the nerve cells (and see if it has moved out of the nucleus). With this imaging software the researchers aim to screen thousands of drug compounds in a short space of time, including some which have been approved for other illnesses. A ‘good’ drug will make TDP-43 stay in the correct location within the nerve cell’s nucleus. Continue reading

Investigating C9orf72 and TDP-43 proteins in a fruitfly model of MND

Background to C9orf72 toxicity

We know that damage to C9orf72 (both the gene and the protein it makes) is a crucial step in why some people get MND and why some people get frontotemporal dementia. There are three possible reasons why C9orf72 is toxic. 1) the way the gene is damaged alters how it normally works. 2) the formation of clumps of RNA – a by-product of the damage and not normally seen in cells, and 3) the formation of very short, new and unwanted proteins called ‘dipeptide repeats’ or ‘DPRs’, again these are not normally seen..

There’s evidence of all three types of toxicity within the motor neurone, but we don’t know how they work together or if one is more toxic than another. We also know that the protein TDP-43 forms clumps in motor neurones affected by the C9orf72 gene. Continue reading

Flying towards an understanding of TDP-43

If you looked at the motor neurones of people with MND down the microscope you would see clumps of a protein called TDP-43. Researchers around the world are working to find why these clumps form and how they are linked to MND.

Dr Jemeen Sreedharan has been looking at the effects of TDP-43 in fruit flies. Initially he investigated how TDP-43 caused its effects, later moving on to find ways to reduce or prevent the damage. He spent the first two years of his MRC and MND Association-funded Fellowship (our reference: 943-795) working at the University of Massachusetts, Boston USA returning last autumn to perform the next stages of his research at the Babraham Institute near Cambridge, UK. Continue reading

Preventing TDP-43 deposits in motor neurones

Deposits of the protein TDP-43 are found within the motor neurones in the majority of cases of MND, and are considered a pathological hallmark of the disease. While we do not fully understand how these deposits are formed, previous research has shown that activation of a process called the Unfolded Protein Response (UPR) can cause TDP-43 protein to deposit in the motor neurones. Continue reading

The role of the protein TDP-43 in MND due to C9orf72 mutations

Mistakes in the C9orf72 gene are the most common cause of inherited MND, and can be linked to about 40% of all cases. Now that we know that damage to the C9orf72 gene causes MND the next step is to understand how this mutation causes the motor neurones to die. In particular Dr Jakub Scaber is looking at how another cause of MND – the formation of clumps of protein called TDP-43 are linked to changes to C9orf72. (You can read more about TDP-43 in the post about Dr Mitchell’s project yesterday).

Jakub Scaber

Dr Jakub Scaber, University of Oxford

Dr Jakub Scaber is a MND Association/ MRC Lady Edith Wolfson Clinical Research Fellow at the University of Oxford, he is studying how mistakes in the C9orf72 gene and TDP-43 protein cause MND (our grant reference: 945-795).

These fellowships are jointly funded by the Association and the Medical Research Council (MRC). They support clinicians (practising doctors) wishing to pursue scientific research and aim to strengthen the links between laboratory and clinic. Our financial commitment to these fellowships varies between £86,000 and £280,000 for up to five years. For this project the total cost of the grant is £173,697 and the MND Association contributes £86,848 with the MRC paying the rest of the money. Continue reading

Understanding and preventing the protein build-up that can cause nerve cells to die

Prior research has already shown that build-up of the protein TDP-43 is found in the majority of cases of MND (irrespective of whether it was caused by an inherited genetic mistake). In healthy nerve cells, TDP-43 is normally found in the cell nucleus (the management centre of the cell). But when we look at nerve cells from people with MND, we see that the TDP-43 has left the nucleus and moved to the main body of the cell and clumped together. We do not know why this happens, or how it leads to cell damage in MND.

In nerve cells, old proteins are ‘tagged’ for breaking down and disposal (or recycling). We have an idea that TDP-43 may impact on this process.

To investigate how TDP-43 causes motor neurones to die, Dr Jacqueline Mitchell and her team at King’s College, London have created several new mouse models to investigate how TDP-43 causes motor neurones to die in MND (our grant reference: 828-791). Continue reading