November 28, 2016

New finding about a protein that enables our brains and muscles to talk, provides new insight into muscular dystrophy

By Toni Baker, Medical College of Georgia, Augusta University

A huge colony of receptors must be optimally positioned and functioning on our muscle cells for our brains to talk with our bodies so we can walk and breathe.

Now scientists have found that a protein believed to help anchor that city of receptors also helps ensure their formation and function and slow their degradation.

The finding provides new insight into how diseases, such as muscular dystrophy, that disconnect brain and body occur, as it points to novel treatment targets, said neuroscientist Dr. Lin Mei. Mei is chairman of the Department of Neuroscience and Regenerative Medicine at the Medical College of Georgia at Augusta University, Georgia Research Alliance Eminent Scholar in Neuroscience and corresponding author of the study in the journal Neuron.

The protein is rapsyn, and the receptors are for acetylcholine, a neurotransmitter that motor neurons release to activate our muscle cells. Rapsyn is made by our muscle cells and considered a sort of biological anchor that interacts with the acetylcholine receptors to ensure that they are optimally positioned for our muscles to receive orders from our brain.

“For precise, efficient synapse function, the receptors have to be extremely highly concentrated at exactly the right place,” Mei said.
The connection, or synapse, the cells form is called the neuromuscular juncture. During development, neurons in the spinal cord reach out to muscle cells to form this direct line of communication. To make that connection, neurons release the protein agrin, which reaches out to LRP4, a protein on the muscle cell surface. This activates MuSK, an enzyme that supports the clustering of receptors on the muscle cell surface that will enable communication.

More info