Understanding and Ameliorating perturbed signalling and pathogenesis in FSHD

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Diseases can be treated more effectively if the causes/mechanisms underlying the symptoms are known. For muscular dystrophy, the causative defect is changes in genes or DNA that in turn, produce changes to proteins. However, it is generally poorly understood how such defects result in the progressive skeletal muscle weakness and wasting typical of muscular dystrophies. Every cell in the body contains the same DNA, which is divided into genes, each of which carries the instructions to make a protein(s): the molecules that build, maintain and operate the body. The selection of genes that are expressed (active) in a particular cell type, such as in a muscle fibre, dictate which proteins are made. This gives the cell its special characteristics and functions. For example, muscle genes are not expressed in skin cells, and skin genes are not expressed in muscle cells.Facioscapulohumeral muscular dystrophy (FSHD) is caused by a change in a particular region of DNA that leads to production of a protein called DUX4, that is not normally present in muscle. DUX4 is a 'transcription factor' meaning that it can control the expression of other genes by binding to their regulatory regions, and so can alter the type of proteins that are made by a cell. Thus the carefully coordinated pattern of gene expression and protein production that enables skeletal muscle to function effectively, is perturbed by the presence of DUX4. This ultimately leads to muscle weakness and wasting.We have examined gene expression changes during human muscle formation in FSHD cells and used mathematical tools to understand which signalling process are perturbed. We found that pathways that control generation of mitochondria and processes associated with mitochondrial function such as dealing with by-products of metabolism/respiration called reactive oxygen species (oxidative stress) are suppressed. It is well known that FSHD cells are more sensitive to oxidative stress, and a recent clinical trial (clinicaltrials.gov number: NCT01596803) reported that administration of anti-oxidants, improved aspects of muscle function in FSHD patients.We have found that inhibiting pathways that control generation of mitochondria in healthy human muscle cells makes them appear like FSHD muscle fibres. Conversely augmenting the action of these pathways controlling generation of mitochondria in FSHD muscle cells makes them more like healthy human muscle cells.This project will investigate how regulation of this pathway controlling generation of mitochondria is perturbed in FSHD and test potential therapeutic strategies to improve its function. Thus in summary, we will generate tools and models of FSHD that will both further reveal disease mechanisms and also provide a platform for testing potential therapies for FSHD, to underpin possible clinical trials. Better understanding the disease mechanism in FSHD may also highlight other potential therapeutic interventions.