Published on 19 February 2015 in the Journal Science, an international team of scientists have found mutations in the gene TBK1 as a contributory risk factor in MND.
The majority of cases of MND are caused by a combination of subtle genetic, environmental and lifestyle factors. These subtle genetic factors in the majority of cases of MND (sometimes known as susceptibility genes) may increase someone’s risk of developing MND, but they do not solely cause the disease (they must be present in combination with a number of other factors in order to tip the balance for someone to develop MND). Find out more here.
Under the leadership of Dr Goldstein, based at Columbia University, the researchers have identified a new MND susceptibility gene – TBK1. The researchers used whole genome sequencing to sequence the entire DNA of over 2,874 MND samples in America – you can find out more about this technique here. By screening a large number of samples, the researchers identified mutations in the TBK1 gene as a common subtle genetic factor involved in some cases of MND in America.
The TBK1 gene is responsible for producing the TBK1 protein (find out more about genes and how they make proteins here). This specific protein is what we scientists like to call an enzyme. Enzymes are a bit like a factory worker within the cell. For example, they work by speeding up the process of making a doll (eg attaching the head to the body). Without them this process would take a long time. However, with them, this process can be done much more quickly and efficiently (allowing there to be enough dolls for the shop to sell).
TBK1 is part of the cell’s recycling system, helping speed up this process in order for the cell to remain ‘waste free’. Normally, in our doll making analogy, TBK1 interacts with the optineurin protein (the head of our doll body). However, researchers have found that the optineurin protein can also become damaged in MND. With TBK1, optineurin and another affected MND protein – p62 – becoming damaged in MND, this whole process of recycling within the cell begins to break down.
By linking the above three MND proteins to one process, TBK1 has enabled the researchers to piece together the cell’s recycling system as being an important process that goes wrong in MND.
Strengthening the links
Dr Brian Dickie, our Director of Research Development, commented on the research “This research has identified TBK1 as a new genetic risk factor in MND. However, it is important to note that this gene would need to be combined with other environmental and lifestyle risk factors in order to ‘tip the balance’ and cause MND.”
“MND researchers have previously identified autophagy (the cell’s recycling system) as an important disease process that goes wrong in MND. By identifying mutations in TBK1, the researchers have importantly linked two other MND-causing genes involved in the break-down of autophagy, p62/SQSMT and OPTN. This means that we are beginning to piece together the MND jigsaw, linking genes and processes that researchers can then go on to ultimately develop targeted treatments.”