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Uptake and antifungal activity of oligonucleotides in Candida albicans
Matthew D Disney1, Constantine G Haidaris, Douglas H Turner
1Department of Chemistry and Center for Human Genetics and Molecular Pediatric Disease, University of Rochester, Rochester, NY 14627-0216, USA.
Abstract:
Candida albicans is a significant cause of disease in immunocompromised humans. Because the number of people infected by fungal pathogens is increasing, strategies are being developed to target RNAs in fungi. This work shows that oligonucleotides can serve as therapeutics against C. albicans. In particular, oligonucleotides are taken up from cell culture medium in an energy-dependent process. After uptake, oligonucleotides, including RNA, remain mostly intact after 12 h in culture. For culture conditions designed for mammalian cells, intracellular concentrations of oligonucleotides in C. albicans exceed those in COS-7 mammalian cells, suggesting that uptake can provide selective targeting of fungi over human cells. A 19-mer 2'OMe (oligonucleotide with a 2'-O-methyl backbone) hairpin is described that inhibits growth of a C. albicans strain at pH < 4.0. This pH is easily tolerated in some parts of the body subject to C. albicans infections. In vivo dimethyl sulfate modification of ribosomal RNA and the decreased rate of protein synthesis suggest that this hairpin's activity may be due to targeting the ribosome in a way that does not depend on base pairing. Addition of anti-C. albicans oligonucleotides to COS-7 mammalian cells has no effect on cell growth. Evidently, oligonucleotides can selectively serve as therapeutics toward C. albicans and, presumably, other pathogens. Information from genome sequencing and functional genomics studies on C. albicans and other pathogens should allow rapid design and testing of other approaches for oligonucleotide therapies.
Insights
Oligonucleotides show promise as antifungal therapeutics against Candida albicans. These molecules are selectively taken up by fungal cells, remaining intact and inhibiting growth, offering a targeted approach for immunocompromised patients.
Area of Science:
- Mycology
- Antimicrobial Therapeutics
- Molecular Biology
Background:
- Candida albicans is a major pathogen in immunocompromised individuals.
- Increasing fungal infections necessitate novel therapeutic strategies.
- Targeting fungal RNA presents a promising avenue for drug development.
Purpose of the Study:
- To investigate the potential of oligonucleotides as therapeutics against Candida albicans.
- To evaluate the uptake, stability, and selective targeting capabilities of oligonucleotides in C. albicans.
- To characterize a specific oligonucleotide that inhibits C. albicans growth.
Main Methods:
- Assessing oligonucleotide uptake in C. albicans via an energy-dependent process.
- Measuring oligonucleotide stability in C. albicans cultures over 12 hours.
- Evaluating the growth inhibitory effects of a 2'OMe hairpin oligonucleotide on C. albicans at low pH.
- Investigating the mechanism of action, including potential ribosome targeting, using dimethyl sulfate modification and protein synthesis assays.
- Testing the effect of anti-C. albicans oligonucleotides on mammalian COS-7 cell growth.
Main Results:
- Oligonucleotides are efficiently taken up by C. albicans in an energy-dependent manner.
- Oligonucleotides remain largely intact within C. albicans for at least 12 hours.
- Intracellular oligonucleotide concentrations in C. albicans are higher than in mammalian cells, indicating selective fungal targeting.
- A 19-mer 2'OMe hairpin oligonucleotide inhibits C. albicans growth at pH < 4.0.
- The hairpin's activity may involve targeting the ribosome independent of base pairing, leading to decreased protein synthesis.
- Oligonucleotides targeting C. albicans showed no adverse effects on mammalian COS-7 cell growth.
Conclusions:
- Oligonucleotides can be selectively taken up and remain stable within Candida albicans, serving as effective antifungal agents.
- A specific 2'OMe hairpin oligonucleotide demonstrates potent growth inhibition of C. albicans, potentially through ribosome targeting.
- Oligonucleotide-based therapies offer a selective and promising approach for treating fungal infections, with potential applicability to other pathogens.