biostudies-literatureRocha HEuropean Union’s Seventh Framework ProgrammeFundação para a Ciência e a TecnologiaEuropean Research CouncilMinistério da Ciência, Tecnologia e Ensino SuperiorNational Institutes of HealthNIH HHSNIGMS NIH HHSe202208154https://www.ebi.ac.uk/biostudies/studies/S-EPMC9930252biostudies-literatureUnknown222(3)A landmark event in the transition from interphase to mitosis in metazoans is nuclear envelope breakdown (NEBD). Important mitotic events occur prior to NEBD, including condensation of replicated chromosomes and assembly of kinetochores to rapidly engage spindle microtubules. Here, we show that nuclear-enriched protein phosphatase 4 (PP4) ensures robust assembly of the microtubule-coupling outer kinetochore prior to NEBD. In the absence of PP4, chromosomes exhibit extended monopolar orientation after NEBD and subsequently mis-segregate. A secondary consequence of diminished outer kinetochore assembly is defective sister chromatid resolution. After NEBD, a cytoplasmic activity compensates for PP4 loss, leading to outer kinetochore assembly and recovery of chromosomes from monopolar orientatThe Journal of cell biologyNuclear-enriched protein phosphatase 4 ensures outer kinetochore assembly prior to nuclear dissolution.PMC9930252SFRH/BD/103495/2014PTDC/BIA-CEL/30507/2017CEECIND/00333/2017ERC-2013-StG-338410-DYNEINOME338410P40 OD010440R01 GM074215UIDB/04293/2020Budrewicz JCarvalho AXDesai ALara-Gonzalez PDumont JGassmann RRocha HSimoes PAfalseNuclear-enriched protein phosphatase 4 ensures outer kinetochore assembly prior to nuclear dissolution.A landmark event in the transition from interphase to mitosis in metazoans is nuclear envelope breakdown (NEBD). Important mitotic events occur prior to NEBD, including condensation of replicated chromosomes and assembly of kinetochores to rapidly engage spindle microtubules. Here, we show that nuclear-enriched protein phosphatase 4 (PP4) ensures robust assembly of the microtubule-coupling outer kinetochore prior to NEBD. In the absence of PP4, chromosomes exhibit extended monopolar orientation after NEBD and subsequently mis-segregate. A secondary consequence of diminished outer kinetochore assembly is defective sister chromatid resolution. After NEBD, a cytoplasmic activity compensates for PP4 loss, leading to outer kinetochore assembly and recovery of chromosomes from monopolar orientat2023-01-01T00:00:00Z2023 Mar2026-05-29T07:45:08.343Z2025-02-19T01:18:05.657ZS-EPMC99302523671939910.1083/jcb.202208154