Maurice Swanson, Ph.D., Professor of Molecular Genetics and Microbiology at University of Florida, Gainesville, and a team of researchers have found that the muscleblind-like 2 (MBNL2) protein in the central nervous system (CNS) may be responsible for the neurological impacts of myotonic dystrophy (DM), providing hope for new treatments. Muscleblind is a type of protein that plays an important role in switching proteins typically found only in babies to proteins found in adults. If this switch isn’t made, an imbalance exists that leads to myotonic dystrophy.
Dr. Swanson states that the team’s work seeks to understand what causes myotonic dystrophy beyond the mutations in the DM1 and DM2 genes.
Dr. Swanson examined which genes were affected by loss of MBNL2 in the brain and found more than 800 affected genes. Many of them had one thing in common: the encoded protein could be made in both fetal and adult forms and MBNL2 appeared to regulate which version was created, according to an article in Neurology Today. One persistent concern that people living with DM1 and DM2 have is the effects of this disease on the brain. “People who don’t have DM usually feel refreshed after a night’s sleep. Myotonic dystrophy patients do not routinely achieve a normal sleep pattern; instead, they have an interrupted series of sleep-wake patterns that do not allow for deep, restful sleep cycles”.
Dr. Swanson created a mouse that lacks the MBNL2 protein as an animal model for DM effects on the CNS. These mice showed normal skeletal muscle structure and function. However, the mice did have DM-related sleep issues, such as a higher number of REM sleep episodes and more REM sleep in general, leading to less restful sleep. In mice lacking MBNL1, another member of the MBNL protein family, the skeletal muscle effects were similar to what is seen in DM. But the central nervous system was not affected, according to Dr. Swanson.
“What we would like to do now is identify the specific cellular events that are abnormal in the DM brain and see if there is something we can do to treat these disease manifestations with focused therapy development. We would also like to understand the heart and muscle problems in DM. We have developed mice with DM-associated problems and we want to use these mouse models to develop effective drug treatments. Also, we want to understand what is so different about the congenital form of DM. Why does it manifest in babies and children? If we can develop animal models for congenital DM, then we can begin to address the important question of what goes wrong during fetal life,” explains Dr. Swanson.
Recently, therapy development for DM has accelerated and treatments based on anti-sense oligonucleotides will hopefully enter clinical trials in the near future. These new studies focused on the roles of MBNL proteins in CNS function should lead to alternative therapeutic strategies designed to reverse effects caused by expression of the mutant DM1 and DM2 genes.