# Identification of components and mechanisms regulating expanded CUG-repeat RNP complexes in Myotonic Dystrophy Type 1 muscle cells

> **NIH NIH R21** · BAYLOR COLLEGE OF MEDICINE · 2024 · $170,720

## Abstract

Project Summary
Myotonic dystrophy (DM) is the most common cause of adult-onset muscular dystrophy and the second most
common cause of muscular dystrophy overall. Myotonic dystrophy type 1 (DM1) results from an expanded
CTG repeat in the 3’ untranslated region of the DMPK gene. The molecular basis for pathogenesis is a toxic
gain of function of the RNA transcribed from the mutant allele that contains long tracts of expanded CUG
repeats (CUGexp RNA). CUGexp RNA remains in the nucleus bound with proteins to form ribonucleoprotein
complexes (RNPs) detected as foci by RNA fluorescence in situ hybridization. CUGexp RNPs include the
Muscleblind-Like (MBNL) paralogs, MBNL1 and MBNL2, that are sequestered resulting in their loss of function
and a primary cause of pathogenesis. CUGexp RNPs are dynamic nuclear structures that are the cause and
therapeutic target of DM1 pathogenesis yet knowledge of the composition of the CUGexp RNP is limited and a
full accounting of the mechanisms of CUGexp RNA toxicity in skeletal muscle remains to be established. To
gain insight into the molecular and cellular biology of CUGexp RNA and the CUGexp RNP in skeletal muscle,
we will use proximity labeling to identify protein and RNA components of the CUGexp RNP complex in addition
to MBNL and CUGexp RNA and determine their roles in CUGexp RNA pathogenesis in skeletal muscle. The
results will provide the foundation to identify novel therapeutic targets and enhance the efficiency of current
approaches targeting the CUGexp RNA component of the RNP.

## Key facts

- **NIH application ID:** 10810789
- **Project number:** 5R21AR081472-02
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** Thomas A Cooper
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $170,720
- **Award type:** 5
- **Project period:** 2023-04-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10810789

## Citation

> US National Institutes of Health, RePORTER application 10810789, Identification of components and mechanisms regulating expanded CUG-repeat RNP complexes in Myotonic Dystrophy Type 1 muscle cells (5R21AR081472-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10810789. Licensed CC0.

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