Rapid nuclear accumulation of injected oligodeoxyribonucleotides

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Intracellular transport and fate of nucleic acids are not well understood.
• Oligodeoxyribonucleotides (oligos) show potential as therapeutic agents, but their cellular behavior requires investigation.

Purpose of the Study:

• To investigate the intracellular transport and nuclear fate of different oligodeoxyribonucleotide (oligo) forms.
• To assess the influence of internucleoside linkage chemistry on oligo localization within mammalian cells.

Main Methods:

• Fluorescently labeled oligodeoxyribonucleotides (phosphodiester, phosphorothioate, methylphosphonate) were microinjected into the cytoplasm of CV-1 epithelial cells and human fibroblasts.
• Cellular localization was analyzed using fluorescence microscopy, comparing oligo diffusion to dextran and examining colocalization with nuclear components.

Main Results:

• Oligos rapidly accumulated in the nucleus, with cytoplasmic migration slower than dextran diffusion.
• Nuclear entry was temperature-dependent but not energy-dependent.
• Intranuclear distribution varied with oligo chemistry: phosphodiester and phosphorothioate oligos colocalized with small nuclear ribonucleoproteins (snRNPs), while methylphosphonate oligos localized with genomic DNA.

Conclusions:

• The chemistry of internucleoside linkages significantly influences the intranuclear distribution of exogenous oligodeoxyribonucleotides.
• These findings enhance understanding of nucleic acid transport in mammalian nuclei.
• The described assay can be used to evaluate the efficacy of therapeutic oligonucleotides.