Investigating the Role of the Drosophila G3BP Protein Rasputin in nanos Expression

Abstract

The regulation of gene expression after a transcript has been produced is mediated by a multiplicity of processes that target the mRNA or protein. Disruptions of these modes of regulation have been implicated in numerous diseases yet the molecular mechanisms involved are not fully understood. During early Drosophila development, the regulation of the maternally-provided nanos (nos) mRNA in the developing oocyte serves as a model to study gene regulation downstream of transcript synthesis. Recently, a potential interaction has been identified between the nos 3’untranslated region (3’UTR) and Rasputin (Rin), the only Drosophila homologue of G3BP, a multifunctional protein conserved across eukaryotes that is overexpressed in numerous human cancers and involved in various biological processes. Although preliminary results suggest that Rin is a positive regulator of nos expression, it is unknown whether Rin targets nos mRNA or Nos protein. Here, we present data that confirm that Rin is a positive regulator of nos during oogenesis. In addition, we offer evidence that regulation of nos by Rin does not require the nos 3’UTR or the nos 5’UTR, thus supporting the hypothesis that Rin-mediated nos regulation occurs post-translationally. Rin may function to inhibit a post-translational modification of Nos that would otherwise target it for degradation in ovaries. Future investigations are suggested for determining the exact mechanism of how Rin regulates nos and to elucidate its importance in Drosophila development. Further characterization of Rin-mediated nos regulation will contribute to our understanding of the multifunctionality of G3BP proteins and inform us about ways that this family of proteins can participate in gene regulation.