Increased levels of a protein called CUGBP1 play an important role in the adult-onset form of muscular dystrophy called myotonic dystrophy type 1, said Baylor College of Medicine researchers in a report that appears in the journal Molecular Cell.
Myotonic dystrophy type 1 is one of a growing number of newly recognized RNA diseases. RNA (ribonucleic acid) or messenger RNA takes the “message” about which proteins to make from the DNA to the protein manufacturing apparatus in the cell's interior or cytoplasm.
Myotonic dystrophy type 1 is the most common adult-onset form of muscular dystrophy. It is associated with hundreds and even thousands of repeats of the nucleotides CTG within a gene called DM kinase protein gene or DMPK. [Cytosine (C), thymine (T), guanine (G) and adenine (A) are all nucleotides that make up DNA. C, G, A, and uracil (U) make up RNA.]
In myotonic dystrophy type 1, the levels of CUGBP1 go up in heart and skeletal muscle, two tissues affected in the disease, because the protein becomes phosphorylated or acquires a phosphate molecule, which causes it to remain in the cell longer than it normally would.
“Normally, during heart development, CUGBP1 regulates alternative splicing (the building of the RNA message that determines which proteins are made by the cell),” said Dr. Thomas A. Cooper, professor of pathology at BCM and senior author of the paper. “But CUGBP1 goes away during normal heart development. In adults, the levels of CUGBP1 should be low.”