Dystrophin – Physiological Role and Function
The largest gene of the human organism, DMD as it is called, is responsible for the production of the dystrophin protein. It is produced in large quantities in muscle cells responsible for the movement of the body (skeletal muscles) and cardiac muscle, while it has been found in nerve cells of the brain in smaller amounts.
In skeletal muscles and heart, dystrophin is one of the proteins that make up a “cluster” that works concertedly to strengthen muscle fibers and works protectively so that they do not get injured during shrinkage and relaxation (Picture 1). It acts as an anchor by connecting the muscle cells and the components that are outside them, possibly by contributing to the communication of these cells. Dystrophin binds to sarcoglycan, a protein cluster containing five transmembrane proteins. Sarcoglycan (affected in LGMDs) binds to the protein cluster of dystroglycan (also affected in LGMDs), that also binds to merosin, the chain of laminin a2 (affected in Congenital Muscular Dystrophies). Sarcoglycan with dystroglycan are called together “cluster related to dystrophin”, where along with dystrophin bind together muscle fibers to extracellular matrix. A specific situation of interaction of muscle – nerve cells is the neuromuscular juction, where another protein called utrophin (Picture 2) is the connection of actin with proteins. A very important role is the one of the receptor of acetylocholine, as well as the rpotein custer MASK/MuSK (often affected in Myasthenia Gravis), Erb R and the protein rapsine. In terms of dystrophin in brain nerve cells, from the little knowledge available, it is certain that it is really important in the physiological structure and function of synapses, ie the connections between nerve cells.
References
http://www.nature.com/nm/journal/v21/n12/full/nm.4006.html DMD Gene – Genetics Home Reference, U.S. National Library of Medicine, National Institutes of Health, https://ghr.nlm.nih.gov/gene/DMD#normalfunction A. C. Keefe, G. Kardon, A New Role for Dystrophin in Muscle Stem Cells, Nature Medicine, 21, pp. 391-1393, 2015.