Experiments Support Looking Outside Nerve Cells in ALS
Researchers in the laboratory of Don Cleveland at the University of California-San Diego have further extended the suspected role of astrocytes, a type of nervous-system “support” cell, in amyotrophic lateral sclerosis (ALS).
The research team, which included MDA grantee Severine Boillee at UCSD and published its findings online Feb. 3 in Nature Neuroscience, found that diminishing production of a toxic protein in these support cells alone sharply slowed disease progression in ALS-affected mice, even when its production remained high in nerve cells.
When production of the toxic protein in astrocytes was high, the disease progressed more rapidly, and neighboring cells called microglia revved up their production of additional toxic compounds.
The toxic protein in astrocytes in these experiments was abnormal SOD1, a protein made from mutated SOD1 genes, a known cause of genetic ALS.
Until recently, many experts believed that the muscle-controlling nerve cells called motor neurons, which die and cause paralysis in ALS, were the central problem in the disease, and that mutated SOD1 genes caused ALS by their poisonous effects on motor neurons alone.
However, recent evidence from this set of experiments and many others, including those by investigators at the University of Iowa showing that mutated SOD1 protein in microglial cells causes major problems (see Unexpected Discovery), have made a good case for looking beyond motor neurons alone for causes and treatment targets in ALS.