Attilio Pane, Kristina Wehr, Trudi Schupbach.
Dept. of Molecular Biology, Princeton University, Princeton, NJ.
RNAi is a widespread mechanism by which organisms regulate gene
expression and defend their genomes against viruses and transposable
elements. Here we report the identification of Drosophila
zucchini (zuc) and squash (squ), two
members of the
“spindle” class genes which function as novel factors in germline RNAi
processes. zuc and squ mutant females are sterile and
produce eggs with a range of dorsal-ventral
defects due to the down-regulation of
Gurken during oogenesis. We show that Zuc and Squ localize to the
perinuclear nuage and interact with Aubergine, a protein belonging
to the PIWI class of Argonaute proteins. These observations point to
a function for Zuc and Squ in RNAi processes. In support of this
conclusion, we find that Oskar protein is ectopically expressed in
early oocytes, where it is normally silenced by RNAi mechanisms.
Furthermore, mutations in zuc and squ induce the
upregulation of Het-A and Tart, two
telomere-specific transposable elements,
and the expression of Stellate protein in the Drosophila germline.
Our results demonstrate that zuc and squ are required
for RNAi mediated silencing of transposable elements and tandem
repeats in the germline and have profound effects on axis formation