A protein that was first identified for playing a key role in regulating normal heart rhythms also appears to be significant in helping muscle cells survive the forces of muscle contraction. Findings that link the protein ankyrin-B (ankB) to the possible prevention of muscular dystrophy were published in the journal Cell.
Vann Bennett, a Howard Hughes Medical Institute investigator and James B. Duke Professor of cell biology, biochemistry, and neurobiology, first discovered ankyrins, or anchor proteins, in red blood cells. They are a family of proteins that assist in attaching other proteins to the fragile cell membranes and in the case of red blood cells help resist shearing forces when blood is pumped vigorously throughout the body.
Bennett's team was exploring the function of ankB, an anchor protein in mice. They found that newborn mice missing ankB had splayed shoulder bones, which stuck out of the animals' backs like wings, rather than lying flat, a symptom of a muscular problem.
"I went back to my pediatric textbook and saw images of people with a form of muscular dystrophy who had splayed shoulder bones," says Bennett. "This opened our eyes to the possibility that, in addition to defects in controlling heart rhythm that we have studied before, the mice might also suffer from muscular dystrophy."
When ankB was absent from mice, they were unable to form properly bundled muscle cells with a protective protein layer. Muscle-contraction forces break the cell membranes—toxins pour in and vital enzymes stream out, killing the cell. Researchers experimented with removing other anchor proteins and found similarly destructive results in adult mice. Although it is too early to tell how or whether these findings can be applied to muscular dystrophy research, Bennett says he is hopeful that this discovery could have broad implications for many cell types.
"Anchors" May Prevent Muscular Dystrophy
April 1, 2009