A new type of molecular profiling may hold clues to muscle degeneration in general and to variations in muscle degeneration among different diseases, says a multinational team of researchers that included MDA grantee Alan Beggs at Children’s Hospital and Harvard Medical School in Boston.
Lou Kunkel, also at Children’s Hospital and Harvard Medical School, and a member of MDA’s Scientific Advisory Committee, coordinated the multinational research team, which published its findings in the Oct. 23 issue of Proceedings of the National Academy of Sciences.
In their paper, the investigators describe how so-called microRNA signatures provide the basis for a new set of potential targets for therapy in several muscle diseases.
MicroRNAs are a recently identified class of very small molecules that regulate gene activity by inactivating genetic information (RNA) that would otherwise lead to the production of proteins.
They can change the way basic processes, including cell death, cell proliferation, tissue development and the immune response take place.
The investigators analyzed 88 muscle samples representing 10 different muscle diseases, including Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), facioscapulohumeral muscular dystrophy (FSHD), types 2A and 2B limb-girdle muscular dystrophies (LGMD2A, LGMD2B), Miyoshi myopathy, nemaline myopathy, polymyositis (PM), dermatomyositis (DM) and inclusion-body myositis (IBM).
Each of the muscle diseases studied proved to have a unique microRNA signature that’s presumably a result of the underlying genetic defect (such as a dystrophin mutation in DMD or BMD) for each disease.
Measuring levels of 18 of the micro-RNA molecules allowed researchers to accurately tell disease-affected muscle tissue from normal muscle tissue and to distinguish among the various muscle diseases.
Although each disease showed its own profile, several diseases showed levels of microRNAs involved in regulating inflammation and the immune response that were different from those seen in the normal muscle samples.
The investigators say that their findings “raise the opportunity for therapeutic intervention at the miRNA [microRNA] level in preventing specific physiological pathways underlying [a] disease.”