BREs Mediate Both Repression and Activation of oskar mRNA Translation and Act In trans

• Published in: Developmental cell Vol. 18; no. 3; pp. 496 - 502
• Main Authors: Reveal, Brad, Yan, Nan, Snee, Mark J., Pai, Chin-I., Gim, Youme, Macdonald, Paul M.
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 16.03.2010; Cell Press
• Subjects: 3' Untranslated Regions; Animals; Animals, Genetically Modified; Base Sequence; Biological and medical sciences; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Cell Polarity; DEVBIO; DNA Primers - genetics; Drosophila; Drosophila - genetics; Drosophila - metabolism; Drosophila Proteins - biosynthesis; Drosophila Proteins - genetics; Female; Fundamental and applied biological sciences. Psychology; Genes, Insect; Molecular and cellular biology; Mutation; Oocytes; Oocytes - metabolism; Protein Biosynthesis; Regulatory Elements, Transcriptional; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-Binding Proteins - genetics; Transcriptional Activation; RNA; DEVBIO; Development; Regulation(control); Activation; Messenger RNA; Repression
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2009.12.021

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. ► Before localization, oskar mRNA translation repressed via BREs in the 3′ UTR ► Some BREs also are bifunctional and also mediate translational activation ► Both BRE functions can act in trans between different oskar transcripts ► Cytoplasmic RNP assembly may facilitate trans activity of regulatory elements