Double-stranded RNA-mediated silencing of genomic tandem repeats and transposable elements in the D. melanogaster germline.
BACKGROUND
The injection of double-stranded RNA (dsRNA) has been shown to induce a potent sequence-specific inhibition of gene function in diverse invertebrate and vertebrate species. The homology-dependent posttranscriptional gene silencing (PTGS) caused by the introduction of transgenes in plants may be mediated by dsRNA. The analysis of Caenorhabditis elegans mutants impaired with dsRNA-mediated silencing and studies in plants implicate a biological role of dsRNA-mediated silencing as a transposon-repression and antiviral mechanism.


RESULTS
We investigated the silencing of testis-expressed Stellate genes by paralogous Su(Ste) tandem repeats, which are known to be involved in the maintenance of male fertility in Drosophila melanogaster. We found that both strands of repressor Su(Ste) repeats are transcribed, producing sense and antisense RNA. The Stellate silencing is associated with the presence of short Su(Ste) RNAs. Cotransfection experiments revealed that Su(Ste) dsRNA can target and eliminate Stellate transcripts in Drosophila cell culture. The short fragment of Stellate gene that is homologous to Su(Ste) was shown to be sufficient to confer Su(Ste)-dependent silencing of a reporter construct in testes. We demonstrated that Su(Ste) dsRNA-mediated silencing affects not only Stellate expression but also the level of sense Su(Ste) RNA providing a negative autogenous regulation of Su(Ste) expression. Mutation in the spindle-E gene relieving Stellate silencing also leads to a derepression of the other genomic tandem repeats and retrotransposons in the germline.


CONCLUSIONS
Homology-dependent gene silencing was shown to be used to inhibit Stellate gene expression in the D. melanogaster germline, ensuring male fertility. dsRNA-mediated silencing may provide a basis for negative autogenous control of gene expression. The related surveillance system is implicated to control expression of retrotransposons in the germline.
Aravin
A A
AA
Department of Animal Molecular Genetics, Institute of Molecular Genetics, 123182, Moscow, Russia.
Naumova
N M
NM
Tulin
A V
AV
Vagin
V V
VV
Rozovsky
Y M
YM
Gvozdev
V A
VA
D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D030801:Animals, Genetically Modified; D002478:Cells, Cultured; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D020868:Gene Silencing; D017344:Genes, Insect; D017930:Genes, Reporter; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D009154:Mutation; D011494:Protein Kinases; D016372:RNA, Antisense / Q000096:biosynthesis; D012330:RNA, Double-Stranded / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics*; D018626:Retroelements; D012689:Sequence Homology, Nucleic Acid; D020080:Tandem Repeat Sequences; D013737:Testis / Q000378:metabolism
D029721:Drosophila Proteins; D019476:Insect Proteins; D016372:RNA, Antisense; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D012097:Repressor Proteins; D018626:Retroelements; C106547:Ssl protein, Drosophila; D011494:Protein Kinases; C094331:Ste protein, Drosophila; D000251:Adenosine Triphosphatases; C096355:spn-E protein, Drosophila