Identification and analysis of transgene-derived endo-siRNAs in Drosophila Schneider cells by Solexa sequencing.
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE16958 | GEO | 2009/09/14
SECONDARY ACCESSION(S): PRJNA117295
REPOSITORIES: GEO
Similar Datasets
Project description:Colonization of genomes by a new selfish genetic element is detrimental to the host species and must lead to an efficient, repressive response. In vertebrates as well as in Drosophila, piRNAs repress transposons in the germ line while endogenous siRNAs take on this role in somatic cells. For endo-siRNAs as well as for piRNAs, it is unclear how an efficient response can be initiated de novo. Our experiments establish that the endo-siRNA pathway will target artificially introduced sequences without the need for a pre-existing template in the genome. This response is also triggered in transiently transfected cells, thus genomic integration is not essential. Deep sequencing revealed that corresponding endo-siRNAs are generated throughout the sequence, but preferentially from transcribed regions. Examination of 3 different cell lines.
2009-09-13 | E-GEOD-16958 | biostudies-arrayexpress
Project description:Transposable elements (TEs) are widely represented in eukaryotic genomes. Recently, a set of small RNAs known as rasRNAs (repeat-associated small RNAs) have been related to the down-regulation of TEs conferring a means to safeguard genome integrity. Two key members of the rasRNAs group are piRNAs and endo-siRNAs. In this study, we have performed a comparative analysis of piRNAs and endo-siRNAs present in mouse oocytes, spermatozoa and zygotes, identified by deep sequencing and bioinformatic analysis. Both piRNAs and endo-siRNAs regulate TEs in addition to other repetitive elements such as tRNAs and rRNAs, suggesting an alternative role of rasRNAs with regard to translation regulation. The detection of piRNAs and endo-siRNAs in sperm cells and revealed also in zygotes, hints to their potential delivery to oocytes during fertilization. However, a comparative assessment of the three cell types indicates that both piRNAs and endo-siRNAs are mainly maternally inherited. Finally, we have assessed the role of the different rasRNA molecules in connection with amplification processes by way of the “ping-pong cycle”. Our results suggest that the ping-pong cycle can act on other rasRNAs, such as tRNA- and rRNA-derived fragments, thus not only being restricted to TEs during gametogenesis, as was evidenced in spermatozoa, oocytes and zygotes.
2014-05-20 | GSE45983 | GEO
Project description:Transposable elements (TEs) are widely represented in eukaryotic genomes. Recently, a set of small RNAs known as rasRNAs (repeat-associated small RNAs) have been related to the down-regulation of TEs conferring a means to safeguard genome integrity. Two key members of the rasRNAs group are piRNAs and endo-siRNAs. In this study, we have performed a comparative analysis of piRNAs and endo-siRNAs present in mouse oocytes, spermatozoa and zygotes, identified by deep sequencing and bioinformatic analysis. Both piRNAs and endo-siRNAs regulate TEs in addition to other repetitive elements such as tRNAs and rRNAs, suggesting an alternative role of rasRNAs with regard to translation regulation. The detection of piRNAs and endo-siRNAs in sperm cells and revealed also in zygotes, hints to their potential delivery to oocytes during fertilization. However, a comparative assessment of the three cell types indicates that both piRNAs and endo-siRNAs are mainly maternally inherited. Finally, we have assessed the role of the different rasRNA molecules in connection with amplification processes by way of the M-bM-^@M-^\ping-pong cycleM-bM-^@M-^]. Our results suggest that the ping-pong cycle can act on other rasRNAs, such as tRNA- and rRNA-derived fragments, thus not only being restricted to TEs during gametogenesis, as was evidenced in spermatozoa, oocytes and zygotes. Comparative analysis from deep sequencing of piRNAs and endo-siRNAs in mouse oocytes, spermatozoa and zygotes
2014-05-20 | E-GEOD-45983 | biostudies-arrayexpress
Project description:Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA as a defense against viral infection. Here, we identify 21-nt long, endogenous siRNAs (endo-siRNAs) corresponding to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to mRNAs: these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form dsRNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease, Dicer-2, and the RNAi effector protein, Ago2. We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma much as piRNAs do in the germ line. Keywords: Small RNA detection and quantification.
2008-04-11 | GSE11019 | GEO
Project description:nbr/CG9247 gene regulates the length of a subset of miRNAs. It is not clear whether Nbr affects the length of other classes of small RNAs, such as piRNAs and endo-siRNAs. To address this, we compared small RNA population in wild-type, Df(2L)BSC312/+, nbr null (nbrf02257/Df(2L)BSC312), (nbr null; pCaSper-nbr (WT)), and (nbr null; pCaSper-nbr (D435A,E437A)). This approach revealed that, in addition to miRNAs, piRNAs and endo-siRNAs were also affected in their length in nbr null and nbr null; pCaSper-nbr (D435A,E437A).
2015-02-02 | GSE50055 | GEO
Project description:Transposable elements are a serious threat for genome integrity and their control via small RNA mediated silencing pathways is an ancient strategy. The fruit fly Drosophila melanogaster has two silencing mechanisms that repress TEs expression: endogenous siRNAs (esiRNAs or endo-siRNAs) and Piwi-interacting small RNAs (piRNAs). The biogenesis of endo-siRNAs involves Loqs-PD, which acts predominantly during processing of dsRNA by Dcr-2, and R2D2 that primarily helps to direct siRNAs for loading into Ago2. We provide deep sequencing evidence consistent with the idea that R2D2 and Loqs-PD can function in part redundantly. Certain transposons display a preference for either dsRBD-protein for production or loading; this appeared to correlate neither with overall abundance, classification of the transposon or a specific site of genomic origin. The endo-siRNA biogenesis pathway in the germline operates according to the same principles as the existing model for the soma, and its impairment does not significantly affect piRNAs. Expanding the analysis, we confirmed the occurrence of somatic piRNA-like RNAs (pilRNAs) that show a ping-pong signature. We detected expression of the Piwi-family protein mRNAs only barely above background, indicating that the somatic pilRNAs may arise from a small sub-population of somatic cells that express a functional piRNA pathway.
2015-01-19 | GSE45290 | GEO
Project description:Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA as a defense against viral infection. Here, we identify 21-nt long, endogenous siRNAs (endo-siRNAs) corresponding to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to mRNAs: these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form dsRNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease, Dicer-2, and the RNAi effector protein, Ago2. We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma much as piRNAs do in the germ line. Keywords: Small RNA detection and quantification. Small RNAs (18-30 nt) from fly heads (WT, ago2 mutants, dcr-2 homozygous and heterozygous mutants, and WT expressing an inverted repeat directed against exon 3 of the gene "white") and S2 cells (transgenic for a construct expressing siRNAs against white and GFP) were sequenced using a Solexa Genome Analyzer instrument. Raw sequence data files for this study are available for download from the SRA FTP site at ftp://ftp.ncbi.nlm.nih.gov/sra/Studies/SRP000/SRP000181
2008-04-10 | E-GEOD-11019 | biostudies-arrayexpress
Project description:Drosophila melanogaster expresses three classes of small RNAs, which are classified according to their mechanisms of biogenesis. MicroRNAs are ~22-23-nt, ubiquitously expressed small RNAs that are sequentially processed from hairpin-like precursors by Drosha/Pasha and Dcr-1/Loquacious complexes. MicroRNAs usually associate with AGO1 and regulate the expression of protein-coding genes. Piwi-interacting RNAs (piRNAs) of ~24-28-nt associate with Piwi-family proteins and can arise from single-stranded precursors. piRNAs function in transposon silencing and are mainly restricted to gonadal tissues. Endo-siRNAs are found in both germline and somatic tissues. These ~21-nt RNAs are produced by a distinct Dicer, Dcr-2, and do not depend on Drosha/Pasha complexes. They predominantly bind to AGO2 and target both mobile elements and protein-coding genes. Surprisingly, a subset of endo-siRNAs strongly depend for their production on the dsRNA-binding protein Loquacious (Loqs), thought generally to be a partner for Dcr-1 and a co-factor for miRNA biogenesis. Endo-siRNA production depends on a specific Loqs isoform, Loqs-PD, which is distinct from the one, Loqs-PB, required for the production of microRNAs. Paralleling their roles in the biogenesis of distinct small RNA classes, Loqs-PD and Loqs-PB bind to different Dicer proteins, with Dcr-1/Loqs-PB complexes and Dcr-2/Loqs-PD complexes driving microRNA and endo-siRNA biogenesis, respectively. Small RNA profiling by high throughput sequencing
2009-07-31 | GSE17171 | GEO
Project description:In Drosophila, siRNAs are classified as endo- or exo-siRNAs based on their origin. Both are processed from double-stranded RNA precursors by Dcr-2, then loaded into the Argonaute protein Ago2. While exo-siRNAs serve to defend the cell against viruses, endo-siRNAs restrict the spread of selfish DNA in somatic cells, analogous to piRNAs in the germ line. Endo- and exo-siRNAs display a differential requirement for double-stranded RNA binding domain proteins (dsRBPs): R2D2 is needed to load exo-siRNAs into Ago2 while the PD isoform of Loquacious (Loqs-PD) stimulates Dcr-2 during the nucleolytic processing of hairpin-derived endo-siRNAs. In cell culture assays, R2D2 antagonizes Loqs-PD in endo-siRNA silencing and Loqs-PD is an inhibitor of RNA interference. Loqs-PD can interact via the C-terminus unique to this isoform with the DExH/D-helicase domain of Drosophila Dcr-2, where binding of R2D2 has also been localized. Separation of the two pathways is not complete; rather, the dicing and Ago2-loading steps appear uncoupled, analogous to the corresponding steps in miRNA biogenesis. Analysis of deep sequencing data further demonstrates that in r2d2 mutant flies, siRNAs can be loaded into Ago2 but not all siRNA classes are equally proficient for this. Thus, the canonical Ago2-RISC loading complex can be bypassed under certain circumstances. Examination of small RNAs from two different mutant strains as well as the corresponding heterozygous controls
2011-02-10 | E-GEOD-26230 | biostudies-arrayexpress
Project description:In Drosophila, siRNAs are classified as endo- or exo-siRNAs based on their origin. Both are processed from double-stranded RNA precursors by Dcr-2, then loaded into the Argonaute protein Ago2. While exo-siRNAs serve to defend the cell against viruses, endo-siRNAs restrict the spread of selfish DNA in somatic cells, analogous to piRNAs in the germ line. Endo- and exo-siRNAs display a differential requirement for double-stranded RNA binding domain proteins (dsRBPs): R2D2 is needed to load exo-siRNAs into Ago2 while the PD isoform of Loquacious (Loqs-PD) stimulates Dcr-2 during the nucleolytic processing of hairpin-derived endo-siRNAs. In cell culture assays, R2D2 antagonizes Loqs-PD in endo-siRNA silencing and Loqs-PD is an inhibitor of RNA interference. Loqs-PD can interact via the C-terminus unique to this isoform with the DExH/D-helicase domain of Drosophila Dcr-2, where binding of R2D2 has also been localized. Separation of the two pathways is not complete; rather, the dicing and Ago2-loading steps appear uncoupled, analogous to the corresponding steps in miRNA biogenesis. Analysis of deep sequencing data further demonstrates that in r2d2 mutant flies, siRNAs can be loaded into Ago2 but not all siRNA classes are equally proficient for this. Thus, the canonical Ago2-RISC loading complex can be bypassed under certain circumstances.
2011-02-10 | GSE26230 | GEO