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Modulation of human prorenin gene expression by antisense oligonucleotides in transfected CHO cells
F Cumin1, F Asselbergs, M Lartigot
1Pharmaceuticals Division, Ciba-Geigy Limited, Basel, Switzerland.
Abstract:
Four phosphorothioate oligonucleotides whose sequences are complementary to the 5' untranslated region, the initiation codon or the coding region of human prorenin mRNA, were studied for their capacity to inhibit gene expression in stably transfected Chinese hamster ovary (CHO) cells constitutively producing human prorenin. In contrast to oligomers complementary to the initiation codon and the coding region, antisense oligomers directed towards the 5' untranslated region have no inhibitory effects. The intracellular delivery of a biotinylated phosphorothioate oligonucleotide (biotin-CATCCATGCTTCCCTC) was monitored in immunofluorescence studies. In the absence of a cationic liposome preparation, Lipofectin, the oligomer failed to penetrate the cells. In the presence of Lipofectin, the 35S-labelled oligomer entered the cells and was distributed in proportions of 54% to the nuclei and 35% to the cytosol. The effects of regular oligonucleotides and of 3'-end and/or 5'-end-modified phosphodiester oligonucleotides on prorenin production were tested. Terminal modification by biotinylation at the 5'-end and/or 3'-dodecyl esterification stabilized oligonucleotides towards exonucleases, but did not translate into a significant inhibition of prorenin production and did not improve the intracellular delivery and or stability of the oligomers. We have shown that it is possible to inhibit prorenin production intracellularly using specific antisense oligonucleotides. Stability and delivery are crucial factors in the design of potent and specific compounds directed at prorenin mRNA.
Insights
Antisense oligonucleotides targeting specific regions of human prorenin mRNA can inhibit gene expression. Intracellular delivery and stability are key factors for effective prorenin inhibition using these compounds.
Area of Science:
- Molecular Biology
- Gene Expression Regulation
- Oligonucleotide Therapeutics
Background:
- Human prorenin plays a role in blood pressure regulation.
- Developing targeted therapies to inhibit prorenin production is of therapeutic interest.
- Antisense oligonucleotides offer a potential strategy for gene silencing.
Purpose of the Study:
- To investigate the efficacy of antisense oligonucleotides in inhibiting human prorenin production.
- To evaluate the impact of oligonucleotide sequence and modifications on gene silencing.
- To assess the role of intracellular delivery and stability in antisense oligonucleotide activity.
Main Methods:
- Synthesis and testing of four phosphorothioate oligonucleotides targeting human prorenin mRNA.
- Utilizing stably transfected Chinese hamster ovary (CHO) cells for gene expression studies.
- Employing immunofluorescence and radiolabeling to monitor intracellular delivery of biotinylated oligonucleotides.
- Evaluating the effects of various oligonucleotide modifications (biotinylation, esterification) on stability and efficacy.
Main Results:
- Antisense oligonucleotides targeting the 5' untranslated region of prorenin mRNA showed no inhibitory effects.
- Oligonucleotides complementary to the initiation codon and coding region demonstrated inhibitory capacity.
- Lipofectin facilitated intracellular delivery of biotinylated oligonucleotides, with distribution to nuclei and cytosol.
- Terminal modifications enhanced exonuclease stability but did not significantly improve prorenin inhibition or delivery.
Conclusions:
- Specific antisense oligonucleotides can effectively inhibit intracellular prorenin production.
- The targeted region within the mRNA is critical for successful gene silencing.
- Optimizing oligonucleotide stability and intracellular delivery is essential for developing potent antisense therapies.