Introduction to Antisense Oligonucleotides
What is ASO
Antisense oligonucleotides are short, synthetic nucleic acid molecules that can be designed to specifically target mRNA molecules and prevent them from being translated into proteins. These molecules have gained a great deal of attention in recent years due to their potential to treat various genetic diseases by targeting disease-causing mutations or controlling overexpression of certain proteins.
What is the Mechanism of Action of ASO
Antisense oligonucleotides work by binding to the target mRNA molecule through complementary base pairing, either by Watson-Crick or Hoogsteen base pairing. This binding can occur in several different ways, such as blocking the ribosome from accessing the mRNA, recruiting RNase H to induce degradation of the mRNA or inhibiting alternative splicing events. The effectiveness of the molecule depends on several factors, including the length and position of the antisense oligonucleotide relative to the target mRNA, the degree of complementarity, and the stability of the resulting duplex structure. The specificity of the antisense oligonucleotide is critical to avoid off-target effects that could cause unintended toxicity and harm.
Delivery of ASO
Antisense oligonucleotides are not readily taken up by cells and require a delivery mechanism to reach their target mRNA. There are several ways to deliver antisense oligonucleotides to cells, including chemical modifications to the oligonucleotide backbone, conjugation to various delivery vehicles, and encapsulation in nanoparticles. Chemical modifications can improve the stability and affinity of the molecule and reduce immunogenicity. Conjugation to delivery vehicles, such as liposomes or proteins, can enhance cellular uptake and improve tissue distribution. Encapsulation in nanoparticles can further protect the oligonucleotide from degradation and offer a sustained-release mechanism.
What are the Applications of ASO?
Antisense oligonucleotides have shown promise in treating various genetic disorders, including inherited genetic diseases, cancer, and viral infections. One of the most well-known applications of antisense oligonucleotides is in treating spinal muscular atrophy (SMA), a debilitating neuropathy caused by mutations in the SMN1 gene. In this case, antisense oligonucleotides are designed to increase the production of the SMN2 gene, which compensates for the loss of SMN1. Other applications of antisense oligonucleotides include treating Duchenne muscular dystrophy, Huntington's disease, and familial hypercholesterolemia.
Design Considerations of ASO
- Hybridization site
mRNA folding into the secondary or tertiary structure is likely to prevent ASOs hybridization. Therefore, the unfolded mRNA region should be selected as the hybridization site.
Once the unfolded region is determined, it should be considered whether the region serves as a binding site for spliceosome, ribosome, protein, or other macromolecular assemblies, such as 5'cap, initiation codon, 3'untranslated region/polyA tail. Even if ASOs fail to activate RNase H, it can spatially block the mechanisms required for mRNA maturation or translation, which may lead to silencing.
- Nuclease degradation
In vivo and in vitro, nuclease activity quickly renders all-natural DNA ASOs useless. All ASOs need to be chemically modified to resist nuclease degradation to be effective.
Content of ASO Synthesis Services
Technical consulting: We provide technical consulting in genetics and molecular biology, including services for site selection, design, purification and characterization of Antisense Oligonucleotides.
ASO design: Select appropriate ASO for specific cells or tissues according to customer needs.
Synthetic ASO: We provide fully automated synthesis techniques and manual synthesis techniques to meet the different requirements of our customers.
