PhD candidate ‘Repeat-expanded RNA in myotonic dystrophy'

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Myotonic dystrophy type 1 (DM1) is the most common inheritable form of muscular dystrophy in adults. Its constellation of symptoms is caused by an expanded (CTG)n repeat in the DMPK gene. There is no cure for DM1 yet, but it is generally accepted that repeat-expanded DMPK RNA is the prime therapeutic target. For the design of effective treatment strategies our understanding of RNA toxicity in DM1 needs refinement. For example, what exactly determines the toxicity of expanded DMPK transcripts? And to which extent must the transcripts of the disease allele be reduced to alleviate symptoms at the cellular level? Hence, we need to identify the contribution of distinct features of expanded DMPK transcripts to RNA toxicity in DM1.

We will apply the CRISPR/Cas9 toolbox to generate muscle cell lines that express expanded DMPK RNAs at different expression levels, with different (CUG)n repeat lengths, and with variable nuclear residence time. We will grow these cells in a biomimetic culture system, approaching the surrounding stimuli of skeletal muscle in patients, to optimize translation of our findings to clinical practice. Cells will be studied under resting, proliferating and differentiating conditions, on different flexible substrates and protein coatings, and under mechanical stimulation to simulate muscle contraction. We thus aim to demonstrate the relevance of separate features of expanded RNA in DM1, which will ultimately help in tailoring drug strategies (e.g., antisense oligonucleotides) to neutralize RNA toxicity.

This project combines complementary expertise from the Myotonic Dystrophy group (Cell Biology) and the Biomaterials group (Dentistry) of the Radboud university medical center.This 4-year-project is funded by the Prinses Beatrix Spierfonds.

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