Cause of ALS, Lou Gehrig's Disease, Found
A University of Wisconsin-Madison researcher has discovered an error in protein formation that could be the root of amyotrophic lateral sclerosis, or ALS.
Also called Lou Gehrig's disease for the New York Yankees first baseman who, at age 36, was forced to retire from baseball in 1939, and died two years later, because of the condition, ALS causes paralysis and death and, according to the ALS Association, currently affects an estimated 30,000 Americans.
After a genetic mutation was discovered in a small group of ALS patients, said a university news release, scientists transferred that gene to animals and began searching for drugs to treat those test subjects.
However, because that approach still needs more development, Su-Chun Zhang, a neuroscientist at the Waisman Center at UW-Madison, and a senior author of the latest study, has been using a different approach -- using lab dishes to study the diseased human cells that direct muscles to contract and are the source of the mutations that lead to ALS.
In the new report, published April 3 in the journal Cell Stem Cell, Zhang, Waisman scientist Hong Chen, and colleagues have narrowed their focus to proteins that build a transport structure inside motor neurons.
Called neurofilament, this structure moves chemicals and cellular materials -- such as neurotransmitters, which signal the muscles, and mitochondria, which process energy to nerve cells.
Zhang explained that motor neurons that control foot muscles are about three feet long, so neurotransmitters must be moved about a yard from where they originate in the body to the location where they can signal the muscles.
A patient lacking that connection ends up paralyzed; hence, the first sign of ALS is often paralysis in the most remote area of the body, the feet and legs.
The neurofilament fulfills both structural and functional roles, Zhang explained.
"Like the studs, joists and rafters of a house, the neurofilament is the backbone of the cell, but it's constantly changing. These proteins need to be shipped from the cell body, where they are produced, to the most distant part, and then be shipped back for recycling," he said. "If the proteins cannot form correctly and be transported easily, they form tangles that cause a cascade of problems."
Zhang's research group found "the disease ALS is caused by misregulation of one step in the production of the neurofilament," he said. "We can put this into action right away. The basic research is now starting to pay off. With a disease like this, there is no time to waste."
Beyond ALS, Zhang says "very similar tangles" appear in Alzheimer's and Parkinson's diseases. "We got really excited at the idea that when you study ALS, you may be looking at the root of many neurodegenerative disorders."