Researchers at the University of Pennsylvania School of Medicine report a novel strategy for stimulating the production of utrophin – an important muscle protein in young mice – for muscular dystrophy therapy.
The investigators gave mdx mice (the mouse model for Duchenne's muscular dystrophy) heregulin, a small molecule to turn on the production of utrophin in their muscles. Utrophin improved muscle function in the mdx mice. "Our strategy boosts the levels of an existing gene using pre-existing cellular machinery rather than having to deliver a gene via gene therapy," says lead author Tejvir S. Khurana, MD, PhD, Assistant Professor of Physiology & Member of the Pennsylvania Muscle Institute.
They detected an approximately threefold increase of utrophin levels over control mdx mice. "This is the level at which one starts seeing a therapeutic affect, as measured in lab tests with mouse muscles," says Khurana. The researchers noted an improvement in the quality of mouse muscle tissue, the biomechanical properties of muscles, and biochemical indices of dystrophy in the muscles.
In patients with Duchenne's muscular dystrophy (DMD), the gene to make the protein dystrophin is missing, which results in the muscle wasting that is associated with the disease. The progressive muscle wasting begins in early childhood and typically leads to death in the twenties. "The gene for utrophin is already in the body, so by giving a small peptide to stimulate its production, we're bypassing the need for dystrophin by cranking up the levels of utrophin," explains Khurana. This research appears in the September 21 issue of the Proceedings of the National Academy of Sciences.