Details

Autor(en) / Beteiligte

• Boesler, Benjamin
• Meier, Doreen
• Förstner, Konrad U.
• Friedrich, Michael
• Hammann, Christian
• Sharma, Cynthia M.
• Nellen, Wolfgang

Titel

Argonaute Proteins Affect siRNA Levels and Accumulation of a Novel Extrachromosomal DNA from the Dictyostelium Retrotransposon DIRS-1

Ist Teil von

• The Journal of biological chemistry, 2014-12, Vol.289 (51), p.35124-35138

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2014

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The retrotransposon DIRS-1 is the most abundant retroelement in Dictyostelium discoideum and constitutes the pericentromeric heterochromatin of the six chromosomes in D. discoideum. The vast majority of cellular siRNAs is derived from DIRS-1, suggesting that the element is controlled by RNAi-related mechanisms. We investigated the role of two of the five Argonaute proteins of D. discoideum, AgnA and AgnB, in DIRS-1 silencing. Deletion of agnA resulted in the accumulation of DIRS-1 transcripts, the expression of DIRS-1-encoded proteins, and the loss of most DIRS-1-derived secondary siRNAs. Simultaneously, extrachromosomal single-stranded DIRS-1 DNA accumulated in the cytoplasm of agnA− strains. These DNA molecules appear to be products of reverse transcription and thus could represent intermediate structures before transposition. We further show that transitivity of endogenous siRNAs is impaired in agnA− strains. The deletion of agnB alone had no strong effect on DIRS-1 transposon regulation. However, in agnA−/agnB− double mutant strains strongly reduced accumulation of extrachromosomal DNA compared with the single agnA− strains was observed. Background: Retroelements are frequently under stringent control by RNAi mechanisms. Results: Disruption of the Argonaut AgnA in Dictyostelium leads to loss of retroelement siRNAs, retroelement-encoded proteins, and accumulation of a cytoplasmic cDNA that is abolished with additional deletion of AgnB. Conclusion: Two Argonautes with different functions are involved in retroelement regulation. Significance: AgnA is required to minimize retroelement expression.