5 research outputs found
BREs Mediate Both Repression and Activation of oskar mRNA Translation and Act In trans
SummaryAsymmetric positioning of proteins within cells is crucial for cell polarization and function. Deployment of Oskar protein at the posterior pole of the Drosophila oocyte relies on localization of the oskar mRNA, repression of its translation prior to localization, and finally activation of translation. Translational repression is mediated by BREs, regulatory elements positioned in two clusters near both ends of the oskar mRNA 3′ UTR. Here we show that some BREs are bifunctional: both clusters of BREs contribute to translational repression, and the 3′ cluster has an additional role in release from BRE-dependent repression. Remarkably, both BRE functions can be provided in trans by an oskar mRNA with wild-type BREs that is itself unable to encode Oskar protein. Regulation in trans is likely enabled by assembly of oskar transcripts in cytoplasmic RNPs. Concentration of transcripts in such RNPs is common, and trans regulation of mRNAs may therefore be widespread
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Bruno contributes to oskar messenger RNA localization during Drosophila oogenesis
Oskar is a body pattern and germ cell determining protein in Drosophila melanogaster. This protein must be properly expressed to ensure correct formation of the posterior pole of the animal. Bruno is a RNA binding protein known to regulate osk mRNA translation during Drosophila oogenesis. In vitro work has implicated Bru in oligomerizing osk mRNA into silencing particles and thereby preventing osk mRNA from accessing translational machinery and inhibiting translation. In attempts to further investigate Bru mediated translational regulation, reporter transcripts with Bruno binding regions from the osk mRNA were analyzed for translation and localization of the transcript. Localization of these reporter transcripts has shown the first in vivo evidence for the Bru mediated silencing particle assembly model. In this thesis, I report on the distribution of reporter transcripts in the Drosophila egg chamber.Cellular and Molecular Biolog