Purdue Biochemist Links ALS to Defect in Protein-Transporting Gene

A biochemist has identified one reason that people develop amyotrophic lateral sclerosis (ALS).

Most cases of ALS are of undetermined origin. But a small percentage is caused by inherited genetic defects, according to a news report from Purdue University in West Lafayette, Ind.

James Clemens, a Purdue University assistant professor of biochemistry, has determined that a gene called VAPB works to transport certain proteins to proper places along neurons in the human body. If the VAPB gene mutates or is missing, "these proteins are unable to make it to locations in neurons where their function is critically required," the Purdue report said.

Purdue says Clemens studied the VAPB gene and discovered that when the gene is mutated, it causes a portion of the genetic types of ALS.

Clemens used fruit flies in his studies of VAPB, which delivers Down syndrome cell adhesion molecule (Dscam) to the axons of the body's neurons. Said Clemens, "VAPB is important for the trafficking of Dscam and potentially other cell surface receptors down axons. This may be the reason why people with mutations of VAPB develop ALS."

ALS is a progressive neurodegenerative disease affecting nerve cells in the brain and spinal cord, according to the ALS Association (ALSA). In ALS patients, motor neurons degenerate and eventually die, which impacts the brain's ability to control muscle movement. There is currently no cure for ALS, and ALSA estimates 30,000 Americans may have the disease at any given time.

Explaining the role that neurons play, Clemens says, "Neurons are all connected. The axon of one neuron sends signals to the dendrites of the next neuron in the circuit.

"If Dscam and other receptors are not delivered to their proper locations in axons, then the connections between axons and dendrites are destabilized, resulting in neuron degeneration. ... We hope that our discovery in fruit flies will ultimately lead to the development of new clinical strategies to detect, treat or prevent ALS."

Clemens's work was published in The Journal of Neuroscience.

About the Author

Laurie Watanabe is the editor of Mobility Management. She can be reached at lwatanabe@1105media.com.

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