Region-specific activation of oskar mRNA translation by inhibition of Bruno-mediated repression

A complex program of translational repression, mRNA localization, and translational activation ensures that Oskar (Osk) protein accumulates only at the posterior pole of the Drosophila oocyte. Inappropriate expression of Osk disrupts embryonic axial patterning, and is lethal. A key factor in transla...

Full description

Saved in:
Bibliographic Details
Published in:PLoS genetics 2015-02, Vol.11 (2), p.e1004992-e1004992
Main Authors: Kim, Goheun, Pai, Chin-I, Sato, Keiji, Person, Maria D, Nakamura, Akira, Macdonald, Paul M
Format: Article
Language:English
Subjects:
3' Untranslated Regions - genetics
Animals
Body Patterning - genetics
Drosophila melanogaster - embryology
Drosophila melanogaster - genetics
Drosophila Proteins - biosynthesis
Drosophila Proteins - genetics
Drosophila Proteins - metabolism
Experiments
Gene Expression Regulation, Developmental
Identification and classification
Insects
Messenger RNA
Methods
Mutation
Oocytes - growth & development
Oocytes - metabolism
Oogenesis - genetics
Physiological aspects
Protein Biosynthesis - genetics
Proteins
Regulatory Sequences, Nucleic Acid
RNA sequencing
RNA, Messenger - biosynthesis
RNA-Binding Proteins - genetics
RNA-Binding Proteins - metabolism
Translation (Genetics)
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A complex program of translational repression, mRNA localization, and translational activation ensures that Oskar (Osk) protein accumulates only at the posterior pole of the Drosophila oocyte. Inappropriate expression of Osk disrupts embryonic axial patterning, and is lethal. A key factor in translational repression is Bruno (Bru), which binds to regulatory elements in the osk mRNA 3' UTR. After posterior localization of osk mRNA, repression by Bru must be alleviated. Here we describe an in vivo assay system to monitor the spatial pattern of Bru-dependent repression, separate from the full complexity of osk regulation. This assay reveals a form of translational activation-region-specific activation-which acts regionally in the oocyte, is not mechanistically coupled to mRNA localization, and functions by inhibiting repression by Bru. We also show that Bru dimerizes and identify mutations that disrupt this interaction to test its role in vivo. Loss of dimerization does not disrupt repression, as might have been expected from an existing model for the mechanism of repression. However, loss of dimerization does impair regional activation of translation, suggesting that dimerization may constrain, not promote, repression. Our work provides new insight into the question of how localized mRNAs become translationally active, showing that repression of osk mRNA is locally inactivated by a mechanism acting independent of mRNA localization.
ISSN:1553-7404
1553-7390
1553-7404
DOI:10.1371/journal.pgen.1004992