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Selective dephosphorylation by PP2A-B55 directs the meiosis I - meiosis II transition in oocytes

ABSTRACT: Meiosis is a specialized cell cycle that requires sequential changes to the cell division machinery to facilitate changing functions. To define the mechanisms that enable the oocyte-to-embryo transition, we performed time-course proteomics in sea star oocytes from prophase I through the first embryonic cleavage. Although protein levels are broadly stable, dynamic waves of phosphorylation underlie each meiotic stage. We find that the phosphatase PP2A-B55 is reactivated at the Meiosis I/II transition resulting in the preferential dephosphorylation of threonine residues. Selective dephosphorylation is critical for directing the MI / MII transition as altering PP2A-B55 substrate preferences disrupts key cell cycle events after meiosis I. In addition, threonine to serine substitution of a conserved phosphorylation site in the substrate INCENP prevents its relocalization at anaphase I. Thus, through its inherent phospho-threonine preference, PP2A-B55 imposes specific phosphoregulated behaviors that distinguish the two meiotic divisions.

INSTRUMENT(S): Orbitrap Fusion Lumos, Orbitrap Fusion

ORGANISM(S): Patiria Miniata (ncbitaxon:46514)

SUBMITTER: Arminja Kettenbach

PROVIDER: MSV000085949 | MassIVE | Fri Aug 14 12:45:00 BST 2020

SECONDARY ACCESSION(S): PXD020916

REPOSITORIES: MassIVE

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