A PP2A-B56—Centered View on Metaphase-to-Anaphase Transition in Mouse Oocyte Meiosis I

Leonor Keating (1, 2, 3) , Sandra Touati (1, 2, 3) , Katja Wassmann (1, 2, 3)

1 LBD - Laboratoire de Biologie du Développement [IBPS]
2 IBPS - Institut de Biologie Paris Seine
3 LBD-E13 - MOM: La meiose dans l'ovocyte des mammifères = MOM: mammalian oocyte meiosis

Meiosis is required to reduce to haploid the diploid genome content of a cell, generating gametes-oocytes and sperm-with the correct number of chromosomes. To achieve this goal, two specialized cell divisions without intermediate S-phase are executed in a time-controlled manner. In mammalian female meiosis, these divisions are error-prone. Human oocytes have an exceptionally high error rate that further increases with age, with significant consequences for human fertility. To understand why errors in chromosome segregation occur at such high rates in oocytes, it is essential to understand the molecular players at work controlling these divisions. In this review, we look at the interplay of kinase and phosphatase activities at the transition from metaphase-to-anaphase for correct segregation of chromosomes. We focus on the activity of PP2A-B56, a key phosphatase for anaphase onset in both mitosis and meiosis. We start by introducing multiple roles PP2A-B56 occupies for progression through mitosis, before laying out whether or not the same principles may apply to the first meiotic division in oocytes, and describing the known meiosis-specific roles of PP2A-B56 and discrepancies with mitotic cell cycle regulation.

Keywords: PP2A; oocyte meiosis; metaphase-to-anaphase transition; spindle assembly checkpoint; error correction; cohesin protection

Domains: Subcellular Processes [q-bio.SC]

Leonor Keating, Sandra Touati, Katja Wassmann. A PP2A-B56—Centered View on Metaphase-to-Anaphase Transition in Mouse Oocyte Meiosis I. Cells, 2020, 9 (2), pp.390. ⟨10.3390/cells9020390⟩. ⟨hal-02553761⟩