The translational regulation of maternal
            mRNA
            s in time and space

Control of mRNA translation is a key mechanism by which the differentiated oocyte transitions to a totipotent embryo. In Drosophila, the PNG kinase complex regulates maternal mRNA translation at the oocyte-to-embryo transition. We previously showed the GNU activating subunit is crucial in regulating PNG and timing its activity to the window between egg activation and early embryogenesis (Hara et al., 2017). In this study, we find associations between GNU and proteins of RNP granules and demonstrate that GNU localizes to cytoplasmic RNP granules in the mature oocyte, identifying GNU as a new component of a subset of RNP granules. Furthermore, we define roles for the domains of GNU. Interactions between GNU and the granule component BIC-C reveal potential conserved functions for translational regulation in metazoan development. We propose that by binding to BIC-C, upon egg activation GNU brings PNG to its initial targets, translational repressors in RNP granules.

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Dynamic changes in the association between maternal mRNAs and endoplasmic reticulum during ascidian early embryogenesis

Development Genes and Evolution ◽

10.1007/s00427-021-00683-y ◽

2021 ◽

Author(s):

Toshiyuki Goto ◽

Shuhei Torii ◽

Aoi Kondo ◽

Junji Kawakami ◽

Haruka Yagi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Translational Regulation ◽

Focused Ion Beam ◽

Ion Beam ◽

Early Embryogenesis ◽

Axis Formation ◽

Second Phase ◽

Dynamic Changes ◽

Maternal Mrna ◽

Maternal Mrnas

AbstractAxis formation is one of the most important events occurring at the beginning of animal development. In the ascidian egg, the antero-posterior axis is established at this time owing to a dynamic cytoplasmic movement called cytoplasmic and cortical reorganisation. During this movement, mitochondria, endoplasmic reticulum (ER), and maternal mRNAs (postplasmic/PEM RNAs) are translocated to the future posterior side. Although accumulating evidence indicates the crucial roles played by the asymmetrical localisation of these organelles and the translational regulation of postplasmic/PEM RNAs, the organisation of ER has not been described in sufficient detail to date owing to technical difficulties. In this study, we developed three different multiple staining protocols for visualising the ER in combination with mitochondria, microtubules, or mRNAs in whole-mount specimens. We defined the internally expanded “dense ER” using these protocols and described cisterna-like structures of the dense ER using focused ion beam-scanning electron microscopy. Most importantly, we described the dynamic changes in the colocalisation of postplasmic/PEM mRNAs and dense ER; for example, macho-1 mRNA was detached and excluded from the dense ER during the second phase of ooplasmic movements. These detailed descriptions of the association between maternal mRNA and ER can provide clues for understanding the translational regulation mechanisms underlying axis determination during ascidian early embryogenesis.

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aubergine enhances oskar translation in the Drosophila ovary

Development ◽

10.1242/dev.122.5.1631 ◽

1996 ◽

Vol 122 (5) ◽

pp. 1631-1639 ◽

Cited By ~ 9

Author(s):

J.E. Wilson ◽

J.E. Connell ◽

P.M. Macdonald

Keyword(s):

Translational Regulation ◽

Genetic Screen ◽

Drosophila Embryo ◽

Dorsoventral Patterning ◽

Maternal Mrna ◽

Body Patterning ◽

The Stability ◽

Drosophila Ovary ◽

New Alleles

Although translational regulation of maternal mRNA is important for proper development of the Drosophila embryo, few genes involved in this process have been identified. In this report, we describe the role of aubergine in oskar translation. Previously, aubergine has been implicated in dorsoventral patterning, as eggs from aubergine mutant mothers are ventralized and seldom fertilized (Schupbach, T. and Wieschaus, E. (1991) Genetics 129, 1119–1136). We have isolated two new alleles of aubergine in a novel genetic screen and have shown that aubergine is also required for posterior body patterning, as the small fraction of eggs from aubergine- mothers that are fertilized develop into embryos which lack abdominal segmentation. Although aubergine mutations do not appear to affect the stability of either oskar mRNA or protein, the level of oskar protein is significantly reduced in aubergine mutants. Thus, aubergine is required to enhance oskar translation. While aubergine-dependence is conferred upon oskar mRNA by sequences in the oskar 3′ UTR, aubergine may influence oskar translation through an interaction with sequences upstream of the oskar 3′ UTR.

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