TSUNAMI: an antisense method to phenocopy splicing-associated diseases in animals

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Spinal muscular atrophy (SMA) is a motor neuron disease resulting from SMN1 gene mutations.
• The SMN2 gene produces insufficient functional SMN protein due to exon 7 skipping.
• Antisense oligonucleotides (ASOs) offer a potential therapeutic strategy by modulating pre-mRNA splicing.

Purpose of the Study:

• To investigate the use of ASOs to phenocopy SMA in a mouse model.
• To establish a disease model for studying splicing-associated pathogenesis.
• To evaluate the potential of ASOs in disease modeling and therapeutic testing.

Main Methods:

• Administration of ASOs designed to exacerbate SMN2 missplicing in transgenic Smn(-/-) mice.
• Intracerebroventricular injection of ASOs in neonatal mice.
• Assessment of SMA-like phenotypes, including motor dysfunction, growth impairment, and survival.
• Analysis of α-motor neuron loss and neuromuscular junction integrity.
• Evaluation of a therapeutic ASO designed to restore SMN2 splicing.

Main Results:

• ASOs exacerbating SMN2 missplicing induced dose-dependent SMA-like phenotypes in mice.
• Intracerebroventricular ASO injection recapitulated key SMA features: motor deficits, growth issues, and reduced lifespan.
• Observed α-motor neuron degeneration and abnormal neuromuscular junctions.
• A therapeutic ASO successfully prevented SMA-like phenotypes by correcting SMN2 splicing.
• Starvation-induced splicing changes, particularly in SMN2, were identified as potential disease accelerators.

Conclusions:

• ASOs can be engineered to induce splicing defects, providing a powerful tool for modeling splicing-associated diseases like SMA.
• This approach enables detailed dissection of disease mechanisms, including onset and progression.
• The model facilitates rapid and accurate testing of potential therapeutic agents for SMA and similar conditions.