BREs mediate both repression and activation of oskar mRNA translation and act in trans.
Asymmetric 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.
Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA.
Brad
B
Reveal
Nan
N
Yan
Mark J
MJ
Snee
Chin-I
CI
Pai
Youme
Y
Gim
Paul M
PM
Macdonald
D020413:3' Untranslated Regions; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D016764:Cell Polarity; D017931:DNA Primers / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D017344:Genes, Insect; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics; D050436:Regulatory Elements, Transcriptional; D015533:Transcriptional Activation
D020413:3' Untranslated Regions; D017931:DNA Primers; D029721:Drosophila Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C093437:bru1 protein, Drosophila; C091675:osk protein, Drosophila