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Stabilization of expanded (CTG)•(CAG) repeats by antisense oligonucleotides
Masayuki Nakamori1, Geneviève Gourdon, Charles A Thornton
1Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA.
Summary
Antisense oligonucleotides (ASOs) targeting toxic RNA in myotonic dystrophy type 1 (DM1) also stabilize the disease-causing CTG repeat expansion. This dual action offers a promising therapeutic strategy for DM1 by reducing RNA toxicity and repeat instability.
Area of Science:
- Molecular Biology
- Genetics
- Neuroscience
Background:
- Myotonic dystrophy type 1 (DM1) is caused by CTG repeat expansions in the DMPK gene.
- The expanded CUG repeat RNA (CUG(exp)) exerts a toxic gain-of-function, driving disease progression.
- Somatic instability of CTG repeats contributes to DM1 pathogenesis.
Purpose of the Study:
- To investigate if CAG-repeat antisense oligonucleotides (ASOs), used to target toxic CUG(exp) RNA, can also reduce the instability of CTG repeats in DM1.
- To evaluate the effect of ASOs on CTG repeat instability in both cellular and animal models of DM1.
Main Methods:
- Treatment of human cells containing (CTG)(800) repeats with CAG-repeat ASOs.
- Direct injection of CAG-repeat ASOs into muscle tissue of mice carrying a DMPK transgene with (CTG)(800) repeats.
- Assessment of CTG repeat instability following ASO treatment.
Main Results:
- CAG-repeat ASOs significantly suppressed the instability of (CTG)(800) repeats in human cells.
- Somatic instability of (CTG)(800) repeats was also suppressed in mouse muscle tissue following ASO injection.
- These findings demonstrate a dual therapeutic effect of ASOs in DM1 models.
Conclusions:
- Antisense oligonucleotides targeting toxic CUG(exp) RNA in DM1 also stabilize the underlying CTG repeat expansions.
- Early intervention with ASOs may offer a combined benefit of reducing RNA toxicity and stabilizing repeat lengths.
- This dual mechanism presents a potentially more effective therapeutic strategy for myotonic dystrophy type 1.
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