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BREs mediate both repression and activation of oskar mRNA translation and act in trans.

ABSTRACT: 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.

SUBMITTER: Reveal B

PROVIDER: S-EPMC2841435 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

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BREs mediate both repression and activation of oskar mRNA translation and act in trans.

Reveal Brad B Yan Nan N Snee Mark J MJ Pai Chin-I CI Gim Youme Y Macdonald Paul M PM

Developmental cell 20100301 3

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 ...[more]

PMID: 20230756

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2020-01-06 | GSE123052 | GEO

Makorin 1 controls embryonic patterning by alleviating Bruno1-mediated repression of oskar translation

Project description:Makorins are evolutionary conserved proteins that contain C3H-type zinc finger modules and a RING E3 ubiquitin ligase domain. In Drosophila maternal Makorin 1 (Mkrn1) has been linked to embryonic patterning but the mechanism remained unsolved. Here, we show that Mkrn1 is essential for axis specification and pole plasm assembly by translational activation of oskar. We demonstrate that Mkrn1 interacts with poly(A) binding protein (pAbp) and binds specifically to osk 3’ UTR in regions overlapping Bruno1 (Bru1) responsive elements (BREs), which regulate osk translation. We observe increased association of the translational repressor Bru1 with osk mRNA upon depletion of Mkrn1, indicating that both proteins compete for osk binding. Consistently, reducing Bru1 dosage partially rescues viability and Osk protein level in ovaries from Mkrn1 females. We conclude that Mkrn1 controls embryonic patterning and germ cell formation by specifically activating osk translation, most likely by competing with Bru1 to bind to osk 3’ UTR.

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