The quality of the neighborhood that motor neurons are in determines whether they are, a new study shows healthy or degenerate. own force inherited the motor neurons is not as important. The results reveal new approaches to therapies for amyotrophic lateral sclerosis (ALS), also known as the disease of Lou Gehrig.
ALS is a neurodegenerative disease in which people lose control of their muscles, which eventually atrophy. Researchers believe that the muscles fade after the motor neurons that innervate die. Although the majority of ALS cases arise spontaneously, about 2% are due to inherited mutations in the gene for superoxide dismutase (SOD1), an enzyme that scavenges free radicals that damage cells. When the mutant SOD1 is overproduced gene in mice, the animals suffer similar progressive neurodegeneration in ALS.
Scientists have long thought that the mutant SOD1 somehow mucks inside functioning motor neurons and kills them, but nobody has been able to prove it. Last year, a research group overexpressed mutant SOD1 in mice - only in motor neurons - but the mice showed no adverse effects. For monitoring, another team led by Don Cleveland at the University of California, San Diego, mice engineered with normal cells and cells with a mutant SOD1 gene to determine if the neighboring cells mutant contribute to neurodegeneration.
researchers found that the only time that motor neurons degenerate was when they were surrounded by mutant helper cells. The higher the percentage of patients helper cells, they report in the October issue 3 Science , plus neurodegeneration and the worst animal disease. However, when helper cells healthy surrounded SOD1 containing motor neurons, neurons are not dead - and the animals lived a normal life span. The researchers were unable to identify what types of helper cells were the most important, but these experiments are underway.
The work should lead to a "change of mentality for neurodegenerative diseases," because the focus has always been on the nerve cells themselves, says neuroscientist Jeffrey Rothstein of the medical school of the Johns Hopkins University. "It is equally important to consider the non-neuronal cells." neighboring cells could be targeted by stem cell therapies that seek to replace the cells carrying the mutation or by drug treatments to correct the defect . He said that the role of neighboring cells is surprising. " I presume they would be this important "
Related Sites
The site of Don Cleveland
Information on ALS NIH
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