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Cells January 1, 2020; 9 (5):

Managing the Oocyte Meiotic Arrest-Lessons from Frogs and Jellyfish.

Jessus C , Munro C , Houliston E .

During oocyte development, meiosis arrests in prophase of the first division for a remarkably prolonged period firstly during oocyte growth, and then when awaiting the appropriate hormonal signals for egg release. This prophase arrest is finally unlocked when locally produced maturation initiation hormones (MIHs) trigger entry into M-phase. Here, we assess the current knowledge of the successive cellular and molecular mechanisms responsible for keeping meiotic progression on hold. We focus on two model organisms, the amphibian Xenopus laevis, and the hydrozoan jellyfish Clytia hemisphaerica. Conserved mechanisms govern the initial meiotic programme of the oocyte prior to oocyte growth and also, much later, the onset of mitotic divisions, via activation of two key kinase systems: Cdk1-Cyclin B/Gwl (MPF) for M-phase activation and Mos-MAPkinase to orchestrate polar body formation and cytostatic (CSF) arrest. In contrast, maintenance of the prophase state of the fully-grown oocyte is assured by highly specific mechanisms, reflecting enormous variation between species in MIHs, MIH receptors and their immediate downstream signalling response. Convergence of multiple signalling pathway components to promote MPF activation in some oocytes, including Xenopus, is likely a heritage of the complex evolutionary history of spawning regulation, but also helps ensure a robust and reliable mechanism for gamete production.

PubMed ID: 32392797
PMC ID: PMC7290932
Article link: Cells
Grant support: [+]

Species referenced: Xenopus
Genes referenced: arpp19 cdk1 gprc6a mastl mos pbrm1 ptpa rasgrf1 wee2
GO keywords: oogenesis

Article Images: [+] show captions
References [+] :
Alexandrova, Oogenesis in Hydra: nurse cells transfer cytoplasm directly to the growing oocyte. 2005, Pubmed