Possible Cause of Movement Defects in Spinal Muscular Atrophy Identified
Post date: May 17, 2013 2:44:14 PM
April 10, 2012
Possible Cause of Movement Defects in Spinal Muscular Atrophy
Identified
ScienceDaily (Apr. 10, 2012) — An abnormally low level of a protein in certain nerve cells is linked to movement problems that characterize the deadly childhood disorder spinal muscular atrophy, new research in animals suggests.
Spinal muscular atrophy, or SMA, is caused when a child's motor neurons -- nerve cells that send signals from the spinal cord to muscles -- produce insufficient amounts of what is called survival motor neuron protein, or SMN. This causes motor neurons to die, leading to muscle weakness and the inability to move.
Though previous research has established the disease's genetic link to SMN in motor neurons, scientists haven't yet uncovered how this lack of SMN does so much damage. Some children with the most severe form of the disease die before age 2.
A research team led by Ohio State University scientists showed in zebrafish that when SMN is missing -- in cells throughout the body as well as in motor neurons specifically -- levels of a protein called plastin 3 also decrease.
When the researchers added plastin 3 back to motor neurons in zebrafish that were genetically altered so they couldn't produce SMN, the zebrafish regained most of their swimming abilities movement that had been severely limited by their reduced SMN. These findings tied the presence of plastin 3 -- alone, without SMN -- to the recovery of lost movement.
The recovery was not complete. Fish without SMN in their cells still eventually died, so the addition of plastin 3 alone is not a therapeutic option. But further defining this protein's role increases understanding of how spinal muscular atrophy develops.