Massive microRNA scan uncovers leads to treating muscle de...( Researchers have discovered the firs...)

Researchers have discovered the first microRNAs tiny bits of code that regulate gene activity linked to each of 10 major degenerative muscular disorders, opening doors to new treatments and a better biological understanding of these debilitating, poorly understood, often untreatable diseases. The study, to be published online this week by the Proceedings of the National Academy of Sciences, was led by Iris Eisenberg, PhD, of the Program in Genomics at Childrens Hospital Boston. Louis Kunkel, PhD, director of the Program in Genomics and an investigator with the Howard Hughes Medical Institute, was senior investigator.

The disorders include the muscular dystrophies (Duchenne muscular dystrophy, Becker muscular dystrophy, limb girdle muscular dystrophies, Miyoshi myopathy, and fascioscapulohumeral muscular dystrophy); the congenital myopathies (nemaline myopathy); and the inflammatory myopathies (polymyositis, dermatomyositis, and inclusion body myositis). While past studies have linked them with an increasing number of genes, it's still largely unknown how these genes cause muscle weakness and wasting, and, more importantly, how to translate the discoveries into treatments.

For instance, most muscular dystrophies begin with a known mutation in a master gene, leading to damaged or absent proteins in muscle cells. In Duchenne and Becker muscular dystrophies, the absent protein is dystrophin, as Kunkel himself discovered in 1987. Its absence causes muscle tissue to weaken and rupture, and the tissue becomes progressively nonfunctional through inflammatory attacks and other damaging events that arent fully understood.

The initial mutations do not explain why patients are losing their muscle so fast, says Eisenberg. There are still many unknown genes involved in these processes, as well as in the inflammatory processes taking place in the damaged muscle tissue.

She and Kunkel believe microRNAs may help provide the missing
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