title: Argonaute proteins affect siRNA levels and accumulation of a novel extrachromosomal DNA from the Dictyostelium retrotransposon DIRS-1.
abstract: 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.
authors.affiliation: From the Department of Genetics, FB10, Kassel University, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Boesler
authors.affiliation: From the Department of Genetics, FB10, Kassel University, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Meier
authors.affiliation: Research Center for Infectious Diseases (ZINF), University of Würzburg, Josef-Schneider-Strasse 2/Bau D15, 97080 Würzburg, Germany, and.
authors.forename: Konrad U
authors.initials: KU
authors.lastname: Förstner
authors.affiliation: From the Department of Genetics, FB10, Kassel University, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Friedrich
authors.affiliation: Ribogenetics Biochemistry Laboratory, School of Engineering and Science, Molecular Life Sciences Research Center, Jacobs University, Campus Ring 1, DE-28759 Bremen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Hammann
authors.affiliation: Research Center for Infectious Diseases (ZINF), University of Würzburg, Josef-Schneider-Strasse 2/Bau D15, 97080 Würzburg, Germany, and.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Sharma
authors.affiliation: From the Department of Genetics, FB10, Kassel University, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany, nellen@uni-kassel.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nellen
mesh_terms: D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D016054:DNA, Protozoan / Q000235:genetics* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D009154:Mutation; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014170:Transformation, Genetic
chemical_list: D060565:Argonaute Proteins; D016054:DNA, Protozoan; D004277:DNA, Single-Stranded; D015800:Protozoan Proteins; D034741:RNA, Small Interfering; D018626:Retroelements
keywords: Argonaute; Gene Silencing; RNA Interference (RNAi); Small Interfering RNA (siRNA); Transposable Element (TE)