Tag: Andy Berglund

X-Ray Crystallography of CUG-Containing RNA Constructs with and Without Small Molecules Could Help Develop Therapeutic Agents to Alleviate Myotonic Dystrophy Symptoms at a Molecular Level

Presenter: Irina Rapoport

Mentor: Andy Berglund

AM Poster Presentation

Poster 37

Myotonic dystrophy is the most common form of adult-onset muscular dystrophy. DM type 1 is caused by aberrantly expanded CTG repeats in the 3’ untranslated region of the DMPK gene. Upon transcription, toxic RNA CUG repeats are formed, which sequester Mbnl proteins, causing abnormal splicing in cells. Some of these abnormal splicing events have been shown to lead to the disease symptoms. Small molecules that release Mbnl sequestration from the toxic RNA could alleviate disease symptoms. I am crystallizing CUG-containing RNA constructs with and without small molecules. Crystal structures would provide direct evidence of where and how the small molecules bind the toxic RNA. Before crystallography, the RNA is deprotected, purified by HPLC, resuspended in buf- fer and annealed. Using Natrix crystallization screens, I test a wide array of conditions for crystal formations. Then, I scale up and vary the most favorable conditions to obtain bigger crystals. Two different RNA constructs, containing three CUG repeats, have crystal- lized well without small molecules under several conditions. A third RNA construct, with two CUG repeats, formed crystals with a small molecule called JFA12046. To screen for additional small molecules with the ability to disrupt the MBNL-CUG complex, we are running competitive electrophoretic mobility shift assays. Long-term, efficiently designed small molecules could be used as therapeutic agents to treat myotonic dystrophy and other diseases with similar molecular mechanisms.

Effects of Pentamidine Derivatives on Myotonic Dystrophy

Presenter : Jessica Choi

Mentor : Andy Berglund

Major : Biochemistry

Poster 8

Myotonic dystrophy (DM) is a genetic disorder caused by an expansion of the trinucleotide (CTG) repeats in myotonic dystrophy protein kinase (DMPK) gene. This disease is characterized by myotonia and is commonly presented as the inability to relax muscles after contraction. Currently, there is no known cure or treatment for this disease. However, a drug called, pentamidine, has been discovered to relieve the severity of the disease by decreasing the level of toxic RNA. More specifically, pentamidine has been demonstrated to rescue RNA splicing, which involves excising out introns and combining exons together in an mRNA sequence to ultimately provide a functioning RNA. Without proper splicing, mutations can give rise to serious diseases like DM. In order to decrease the severity of DM, a high concentration of this drug must be administered, which also inevitably results in a significant decrease in cell viability. Thus, designing a derivative of pentamidine with higher efficacy and lower toxicity is the primary goal of this project. Performing a simple substitution reaction (SN2) from a cyano group-containing core compounds and n-butyl lithium is an easy, yet powerful method to produce the derivatives. Some previously synthesized derivatives have shown promising results with less nega- tive effects on cell viability (less toxic) and increased levels of splicing rescue, although further study needs to continue to search for the most effective drug.the overall success of these organisms.