aubergine gene overexpression in somatic tissues of aubergine(sting) mutants interferes with the RNAi pathway of a yellow hairpin dsRNA in Drosophila melanogaster.

AUBERGINE (AUB) is a member of the PPD family of proteins. These proteins are implicated in RNA interference. In this article we demonstrate that the expression of the aub gene and protein increase in aub(sting) mutants. We used a genetic method to test whether aub(sting) overexpression could interfere with proper functioning of the process of RNA interference in somatic tissues of Drosophila melanogaster. This method is based on a transgenic line bearing a construct in which a fragment of the yellow (y) gene is cloned to form an inverted repeat (y-IR) under the control of the upstream activation sequence (UAS) of the yeast transcriptional activator GAL4. The UAS-y-IR transgene and the Act5C-GAL4 driver were brought together on chromosome 3 via recombination. In the resulting strain (Act5C-y-IR), transcriptional activation by GAL4 constitutively produces a dsRNA hairpin bearing cognate sequences to the yellow gene causing continuing degradation of y mRNA resulting in yellow(1) (y(1)) phenocopies. In this genetic background, the mutation of any factor involved in RNAi should repress degradation of y mRNA, restoring the wild-type phenotype. We employed this genetic approach to show that an increased amount of AUBERGINE interferes with the regular functioning of the somatic RNAi pathway.