Posted on 14/12/2010
Researchers from the School of Biological Sciences at Royal Holloway, University of London have revealed that by using innovative technology to block the activity of myostatin – a protein that prevents muscles from growing bigger and stronger – it may be possible to build up muscle size and strength in people with muscle disease.
The team, led by Professor George Dickson, found that small pieces of DNA called antisense oligonucleotides (AOs) were able to inactivate myostatin in muscle cells grown in the laboratory. This ‘exon skipping’ technology could be used to control the activity of myostatin.
Myostatin is an inhibitor of muscle growth and, together with other proteins that promote muscle growth, works to keep the size and strength of muscle within the normal range. Researchers have shown in animals that blocking the activity of myostatin causes the muscles to increase in strength and size. This approach can be a useful way to "bulk up" muscles in people with muscle disease, helping to increase their muscle strength.
Professor Dickson decided to investigate using exon skipping to block myostatin activity following recent research that suggested this technology could be used to block the activity of certain genes. Exon skipping is currently in clinical trial for Duchenne muscular dystrophy in both the UK and Europe, where the AOs are being used to restore the production of the dystrophin protein. Initial results have been promising and the treatment has been well tolerated by the trial participants.
Exon skipping works by masking part of a gene – an exon – so that the cell skips over it when the protein is being produced. In the case of exon skipping for Duchenne muscular dystrophy, the AOs are designed to specifically mask the part of the dystrophin gene that contains a mistake, allowing a shortened but functional version of the protein to be made. The same technology can be applied to a healthy gene to disrupt the instructions and prevent protein production.
The results of this study, part-funded by the Muscular Dystrophy Campaign, show that exon skipping could be used to block myostatin activity. It is possible that this approach could be used for a range of neuromuscular conditions and may work best in conjunction with other types of therapy so that both the primary cause of the muscle condition is treated and the muscle strength and size is built up.
This approach to treating muscle wasting illnesses may also have advantages over other methods being developed – such as gene therapy and the use of antibodies to block myostatin – which could cause an immune reaction or produce undesirable side effects in patients. It is already known from recent trials for Duchenne muscular dystrophy that AOs are well tolerated in humans.
Professor Dickson said: “We are pleased and excited by these results which suggest that general muscle wasting and weakness which is associated with many neuromuscular diseases may be amenable to treatment by myostatin exon skipping. In the case of Duchenne muscular dystrophy, we envisage a cocktail of exon skipping "drugs" targeting both dystrophin and myostatin at the same time. Such an approach offers the prospect not only to rescue muscles from dystrophin deficiency but also to retrieve muscle size and strength.”
This research is published in Molecular Therapy.