Hairpin dsRNA does not trigger RNA interference in Candida albicans cells
Janet F Staab1, Theodore C White, Kieren A Marr
1Department of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD, USA. jstaab1@jhmi.edu
Yeast (Chichester, England)
|August 26, 2010
Summary
RNA interference (RNAi) is common in eukaryotes, but Candida albicans does not silence ADE2 mRNA using dsRNA. This suggests unknown factors regulate RNAi pathways in this fungal pathogen.
Area of Science:
- Molecular Biology
- Mycology
- Genetics
Background:
- RNA interference (RNAi) is a conserved gene silencing mechanism in eukaryotes, utilizing small RNAs and Argonaute proteins.
- Candida albicans, a fungal pathogen, possesses key RNAi components like Argonaute and a non-canonical Dicer.
- The presence of small interfering RNAs (siRNAs) in the C. albicans transcriptome suggests potential RNAi activity.
Purpose of the Study:
- To investigate the functionality of RNA interference (RNAi) pathways in the fungal pathogen Candida albicans.
- To determine if expressing a double-stranded RNA (dsRNA) hairpin targeting ADE2 mRNA can induce gene silencing in C. albicans.
- To explore the role of Dicer and Argonaute in potential RNAi mechanisms within C. albicans.
Main Methods:
- Engineered expression of an ADE2-targeting dsRNA hairpin in Candida albicans.
- Assessed ADE2 mRNA levels and adenine auxotrophy in engineered strains.
- Performed cell-free assays to evaluate dsRNA processing by C. albicans Dicer.
Main Results:
- Expression of the dsRNA hairpin did not lead to ADE2 mRNA down-regulation or adenine auxotrophy.
- Cell-free assays confirmed that C. albicans Dicer can process the hairpin dsRNA.
- The inability to induce silencing was not due to the dsRNA trigger's structure or Dicer's activity.
Conclusions:
- Despite possessing core RNAi machinery, Candida albicans does not exhibit functional RNA interference via dsRNA hairpin expression targeting ADE2.
- The Dicer enzyme in C. albicans can process dsRNA, indicating the issue lies downstream in the silencing pathway.
- Unknown cellular factors or mechanisms likely regulate siRNA functionality and RNAi pathway efficacy in C. albicans transgenes.
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