Peptide-assisted systemic delivery of therapeutic antisense oligonucleotides in a spinal muscular atrophy model
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by homozygous loss of the survival motor neuron 1 (SMN1) gene. It results in progressive atrophy of voluntary muscle groups leading to paralysis and eventually premature infantile death. In this project, we will develop a peptide-based delivery system that can shuttle antisense oligonucleotides (ASO) to the spinal cord using an axonal retrograde transport system.
Humans have a second, nearly identical copy of the SMN1 gene, SMN2. The 90% majority of SMN2 transcripts lack exon-7, which leads to the production of a truncated SMN protein that is highly unstable. Therefore, increasing the expression of full-length functional SMN protein by forcing SMN2 exon-7 inclusion is a rational therapeutic development for SMA patients.
Antisense oligonucleotides (ASO) targetting SMN2 exon 7 inslcuion have been developed which inhibit binding of small nuclear ribonucleic proteins (snRNPs) and can restore full-length SMN2 which leads to the production of functional SMN protein. However, the delivery of ASO to the spinal motor neurons remains a challenge. In this project, we will develop a peptide-based delivery system that can shuttle ASO to the spinal cord using an axonal retrograde transport system.
- Synthesis of targeted axonal import (TAxI) peptide and conjugation to ASO.
- Validation of the peptide-ASO in SMA patient-derived fibroblast for SMN2 splice correction using RT-qPCR.
- Intramuscular (gastrocnemius) injection of peptide-ASO in Δ7SMA mice. Analysis of spinal cord for full-length SMN2 upregulation using RT-qPCR and western blot analysis.