More muscle power. Mice treated with antisense RNA (bottom) produced more dystrophin - red in this image - mice than controls (top)
A gene therapy can improve muscle shortcut. function in mice with a disease of muscular dystrophy, scientists have found. The trick is to inject an RNA molecule that can help eliminate the genetic mutation in muscle cells. This allows the gene to be translated into a functional protein reasonably.
Muscular dystrophy, a disease caused by a genetic mutation on the X chromosome, primarily affects boys and is available in several varieties. People suffering from Duchenne muscular dystrophy - one of the most severe types - CAN NOT produce dystrophin, the muscle protein; most die of heart failure or other problems in their early 20s Presentation of the normal dystrophin gene in the muscles could theoretically induce cells to produce dystrophin. But it is difficult because the dystrophin gene is huge and unwieldy.
In recent years, several teams began to test another approach. Like most genes, RNA dystrophin protein undergoes a process called splicing, in which extends the so-called "junk" are tailor. Researchers exploit this step by introducing a short stretch of RNA is the genetic mirror image of the Duchenne mutation. This RNA "antisense" binds to RNA molecules from the defective region; accordingly, the splicers interpret the change as junk and eliminate it. The result is an almost normal RNA. But although the method had obtained good results in Petri dishes, the approach did not work as well in animals.
Muscle biologists Qi Lu long and Terence Partridge in Clinical Sciences Centre Medical Research Council in London, UK, and colleagues decided to antisense strategy combined with a chemical often used in therapy gene because it is known to improve the delivery of DNA into cells. The group felt that it could do the same for RNA. When the combination was injected into a large muscle at the diseased mice, gave rise to dystrophin levels that were 20% of normal, compared to none in the controls. That was enough for the muscle to carry some weight, and injection product dystrophin for 3 months, the group reports in the online July 6 Nature Medicine.
"It is very encouraging," said neuroscientist Thomas Rando of Stanford University in California. The challenge now, he believes, is to provide antisense RNA in the blood, it becomes integrated into many muscles at once, and modify it to last longer.
Related Sites
Information on Muscular Dystrophy National Institutes of Health
research on muscular dystrophy Muscular Dystrophy Association
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