Greatwall-Endos-PP2A/B55ᵀʷᶦⁿˢ network regulates translation and stability of maternal transcripts in the Drosophila oocyte-to-embryo transition

Creators: Rangone, Hélène; Bond, Laura; Weil, Timothy T.; Glover, David M.¹

1. California Institute of Technology

Abstract

The transition from oocyte to embryo requires translation of maternally provided transcripts that in Drosophila is activated by Pan Gu kinase to release a rapid succession of 13 mitotic cycles. Mitotic entry is promoted by several protein kinases that include Greatwall/Mastl, whose Endosulfine substrates antagonize Protein Phosphatase 2A (PP2A), facilitating mitotic Cyclin-dependent kinase 1/Cyclin B kinase activity. Here we show that hyperactive greatwall^Scant can not only be suppressed by mutants in its Endos substrate but also by mutants in Pan Gu kinase subunits. Conversely, mutants in me31B or trailer hitch, which encode a complex that represses hundreds of maternal mRNAs, enhance greatwall^Scant . Me31B and Trailer Hitch proteins, known substrates of Pan Gu kinase, copurify with Endos. This echoes findings that budding yeast Dhh1, orthologue of Me31B, associates with Igo1/2, orthologues of Endos and substrates of the Rim15, orthologue of Greatwall. endos-derived mutant embryos show reduced Me31B and elevated transcripts for the mitotic activators Cyclin B, Polo and Twine/Cdc25. Together, our findings demonstrate a previously unappreciated conservation of the Greatwall-Endosulfine pathway in regulating translational repressors and its interactions with the Pan Gu kinase pathway to regulate translation and/or stability of maternal mRNAs upon egg activation.

Copyright and License

© 2024 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.

Acknowledgement

We are grateful to Terry Orr-Weaver, Akira Nakamura and Hiroyuki Ohkura for kindly providing flies, antibodies and plasmid; to Adelaide Carpenter for fly stocks and the initial screens for suppressors of polo¹ gwl^Scant/++ female sterility; to Mingwei Min, Rhys Grant, Fabien Briatte, Richard Butler and Alex Sossick for support with data analysis. We thank Carlos Bettencourt for his contribution to early studies of the png phenotype funded through the NIH MHIRT programme from the National Center on Minority Health and Health Disparities. We thank the Bloomington Drosophila Stock Center (BDSC) and the Fly Facility at the Department of Genetics (University of Cambridge) for fly stocks and the Laboratory of Mass Spectrometry, IBB PAS (Warsaw) for mass spectrometry analysis. We also thank members of the Glover lab for the helpful discussion.

We dedicate this paper to the memory of the late Adelaide Carpenter, who opened the doors to many studies of the regulation of meiosis and mitosis in Drosophila and who laid the foundations for this current work.

Funding

This work was supported by grants from the Wellcome Trust (RG84496) and the NIH (R01NS119614) to D.M.G.

Data Availability

The published article includes mass spectrometry data generated by immunoprecipitation of Endos, CLIP190, CP190 and Cyclin B. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE [65] partner repository with the dataset identifier PXD036613. Python codes used for Me31B::GFP granules analysis are provided as electronic supplementary material [68].

Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.7262706.

Ethics

This work did not require ethical approval from a human subject or animal welfare committee.

Conflict of Interest

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