This diagram illustrates the mechanism by which Toc-HDO-dependent targetRNA gene expression regulation is regulated. Double-stranded TocHDO can be recognized by ANXA5 or CA8. Toc-HDO may be cleaved in the cytoplasm, although its mechanisms are still not fully understood. The parental ASO generated from Toc-HDO is then translocated into the nucleus, where it regulates RNA expression through functional duplexes (ASORNA). Credit: Tokyo Medical and Dental UniversityGene silencing therapies can be used to block or silence the expression of genes associated with certain disorders. TMDU now has some insight into the cellular mechanisms that silencing therapies work in cells.Antisense Oligonucleotide therapies (ASO) use small strands or RNA of DNA and RNA that are complementary to the associated gene to disrupt its expression. ASO therapies are available for certain diseases, including neurological disorders. However, their use is still in its infancy. It is well-known that chemical modification of ASOs can increase the effectiveness of the therapy. The TMDU team had achieved gene silencing previously by attaching alpha tocopherol (Toc), to ASOs. Toc-HDOs were created by attaching Toc DNA/RNA heteroduplex Oligonucleotides to create double-stranded molecules that consist of one strand each of DNA and RNA. Toc-HDOs have a greater therapeutic potential because they are more potent, stable and efficiently taken up in target tissues than ASOs.But, we don't know much about the mechanism of Toc-HDOs. ASOs interact with proteins at all stages of gene silencing, but no ASOs have been identified to do so for Toc-HDOs. Toc-HDO may also have therapeutic properties that are different from other ASOs. This could explain the higher potency.The researchers have identified four proteins in the latest study: annexin A5 or ANXA5, carbonic anhydrase 8, carbonic anhydrase eight (CA8) and apurinic/apyrimidinic Endodeoxyribonuclease1 (APEX1) and flap structure-specific epilease1 (FEN1) all of which bind Toc-HDO. Ken Asada, the lead author of this study, said that he injected mice with fluorescently labeled Toc-HDOs in order to identify binding proteins. "We then characterized these proteins and found that they can bind directly with Toc-HDOs, in vitro."These four proteins are responsible for controlling the function of TocHDO. They may also bind together to create a complex that regulates gene silencing. Takanori Yokota (senior author) said that Tocopherol increased the binding activity of the proteins. This mechanism could explain the higher therapeutic potential of Toc-HDOs.Researchers discovered a novel biological mechanism that allowed them to increase our understanding of the role of Toc-HDOs in silence genes. This discovery will lead to improved gene silencing therapies, which are more effective and less toxic, which will greatly advance the field.Continue reading Making therapeutic use of antisense OligonucleotidesMore information: Ken Asada and colleagues, Short DNA/RNA homoduplex oligonucleotide interfering proteins are key regulators for target gene silencing. Nucleic Acids research (2021). Information from Journal: Nucleic Acids research Ken Asada and colleagues, Short DNA/RNA heteroduplex Oligonucleotide Interacting Proteins are Key Regulators of Target Gene Silencing. (2021). DOI: 10.1093/nar/gkab258Tokyo Medical and Dental University.
