The researchers found that when neurons with the SOD1 mutation were surrounded by glia with normal genes, the glia were able to stave off the disease. But when mutant glia cells encircled genetically normal motor neurons, the motor neurons were attacked by the glia.
The finding could someday lead to a new therapy for treating ALS. A major line of attack against ALS is to replace motor neurons with stem cells, which would have to re-grow long distances to the muscles in order to work. "In place of this herculean task, we can supply normal supporting cells to prevent the degeneration of motor neurons," says Cleveland.
The researchers will next investigate the mechanism of the glia cell attack. The team found clues that the glia no longer keep the environment safe for neurons, and that they may mount a lethal inflammatory response against the neurons.
In other work, scientists at the Swiss Federal Institute of Technology of Lausanne (EPFL) tackled a different genetic approach against the familial form of ALS that targets the SOD1 gene. Patrick Aebischer, MD, and Cdric Raoul, PhD, used a technology called RNA interference to shut off the toxic SOD1 mutant gene that causes the motor neuron disorder in ALS mice models.
RNA, or ribonucleic acid, is a molecular intermediate between DNA and protein. Each DNA gene holds the code for production of a particular protein. That code is read, or transcribed, by cellular machinery to make a copy of messenger RNA (mRNA). Each piece of mRNA is then translated into the protein. RNA interference is a cellular process that leads to the destruction of a specific mRNA target by naturally occurring RNA pieces.
To inhibit SOD1 mutant gene expression, the researchers engineered a virus to deliver molecular instructions that activate RNA interference. Once inside the cell nucleus, the virus sends a genetic signal to destroy mutant SOD1 messenger RNA. By destroying the
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Contact: Leah Arinello
dawn@sfn.org
202-462-6688
Society for Neuroscience
24-Oct-2004