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The stability, toxicity and effectiveness of unmodified and phosphorothioate antisense oligodeoxynucleotides in
T M Woolf1, C G Jennings, M Rebagliati
1Department of Biochemistry and Molecular Biology, Harvard University, Cambridge.
Abstract:
The properties of antisense phosphorothioate and unmodified oligodeoxynucleotides have been studied in Xenopus oocytes and embryos. We find that phosphorothioates, like unmodified oligodeoxynucleotides, can degrade Vg1 mRNA in oocytes via an endogenous RNase H-like activity. In oocytes, phosphorothioate oligodeoxynucleotides are more stable than unmodified oligodeoxynucleotides and are more effective in degrading Vg1 mRNA. In embryos, neither unmodified nor phosphorothioate deoxyoligonucleotides were effective in degrading Vg1 message at sub-toxic doses.
Insights
Phosphorothioate oligodeoxynucleotides are more stable and effective at degrading Vg1 mRNA in Xenopus oocytes. However, neither phosphorothioate nor unmodified oligodeoxynucleotides effectively degrade Vg1 mRNA in Xenopus embryos at sub-toxic doses.
Area of Science:
- Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Antisense oligodeoxynucleotides are short nucleic acid sequences used to modulate gene expression.
- Phosphorothioate modification enhances nuclease resistance and cellular uptake of oligodeoxynucleotides.
- Vg1 mRNA is a key maternal factor in Xenopus development.
Purpose of the Study:
- To investigate the properties and efficacy of antisense phosphorothioate and unmodified oligodeoxynucleotides in Xenopus oocytes and embryos.
- To compare the stability and mRNA degrading activity of these two types of oligodeoxynucleotides.
Main Methods:
- Treatment of Xenopus oocytes and embryos with phosphorothioate and unmodified oligodeoxynucleotides.
- Assessment of Vg1 mRNA levels using endogenous RNase H-like activity.
- Evaluation of oligodeoxynucleotide stability and degradation efficacy.
Main Results:
- Phosphorothioate oligodeoxynucleotides demonstrated greater stability and were more effective in degrading Vg1 mRNA in Xenopus oocytes compared to unmodified oligodeoxynucleotides.
- Both types of oligodeoxynucleotides were ineffective in degrading Vg1 mRNA in Xenopus embryos at sub-toxic concentrations.
- An endogenous RNase H-like activity was identified as the mechanism for Vg1 mRNA degradation by oligodeoxynucleotides in oocytes.
Conclusions:
- Phosphorothioate oligodeoxynucleotides show promise for Vg1 mRNA targeting in Xenopus oocytes due to enhanced stability and efficacy.
- Oligodeoxynucleotide-mediated Vg1 mRNA degradation is stage-specific, being effective in oocytes but not in embryos at tested doses.