Two bistable switches govern M phase entry
The abrupt and irreversible transition from interphase to M phase is essential to separate DNA replication from chromosome segregation. This transition requires the switch-like phosphorylation of hundreds of proteins by the cyclin-dependent kinase 1 (Cdk1):cyclin B (CycB) complex. Previous studies h...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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Cell Press
2016
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| _version_ | 1797085362539986944 |
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| author | Mochida, S Rata, S Hino, H Nagai, T Novák, B |
| author_facet | Mochida, S Rata, S Hino, H Nagai, T Novák, B |
| author_sort | Mochida, S |
| collection | OXFORD |
| description | The abrupt and irreversible transition from interphase to M phase is essential to separate DNA replication from chromosome segregation. This transition requires the switch-like phosphorylation of hundreds of proteins by the cyclin-dependent kinase 1 (Cdk1):cyclin B (CycB) complex. Previous studies have ascribed these switch-like phosphorylations to the auto-activation of Cdk1:CycB through the removal of inhibitory phosphorylations on Cdk1-Tyr15 [1, 2]. The positive feedback in Cdk1 activation creates a bistable switch that makes mitotic commitment irreversible [2-4]. Here, we surprisingly find that Cdk1 auto-activation is dispensable for irreversible, switch-like mitotic entry due to a second mechanism, whereby Cdk1:CycB inhibits its counteracting phosphatase (PP2A:B55). We show that the PP2A:B55-inhibiting Greatwall (Gwl)-endosulfine (ENSA) pathway is both necessary and sufficient for switch-like phosphorylations of mitotic substrates. Using purified components of the Gwl-ENSA pathway in a reconstituted system, we found a sharp Cdk1 threshold for phosphorylation of a luminescent mitotic substrate. The Cdk1 threshold to induce mitotic phosphorylation is distinctly higher than the Cdk1 threshold required to maintain these phosphorylations-evidence for bistability. A combination of mathematical modeling and biochemical reconstitution show that the bistable behavior of the Gwl-ENSA pathway emerges from its mutual antagonism with PP2A:B55. Our results demonstrate that two interlinked bistable mechanisms provide a robust solution for irreversible and switch-like mitotic entry. |
| first_indexed | 2024-03-07T02:07:54Z |
| format | Journal article |
| id | oxford-uuid:9f9daa4b-a021-45ab-8d28-91be0e6bd009 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:07:54Z |
| publishDate | 2016 |
| publisher | Cell Press |
| record_format | dspace |
| spelling | oxford-uuid:9f9daa4b-a021-45ab-8d28-91be0e6bd0092022-03-27T00:59:21ZTwo bistable switches govern M phase entryJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:9f9daa4b-a021-45ab-8d28-91be0e6bd009EnglishSymplectic Elements at OxfordCell Press2016Mochida, SRata, SHino, HNagai, TNovák, BThe abrupt and irreversible transition from interphase to M phase is essential to separate DNA replication from chromosome segregation. This transition requires the switch-like phosphorylation of hundreds of proteins by the cyclin-dependent kinase 1 (Cdk1):cyclin B (CycB) complex. Previous studies have ascribed these switch-like phosphorylations to the auto-activation of Cdk1:CycB through the removal of inhibitory phosphorylations on Cdk1-Tyr15 [1, 2]. The positive feedback in Cdk1 activation creates a bistable switch that makes mitotic commitment irreversible [2-4]. Here, we surprisingly find that Cdk1 auto-activation is dispensable for irreversible, switch-like mitotic entry due to a second mechanism, whereby Cdk1:CycB inhibits its counteracting phosphatase (PP2A:B55). We show that the PP2A:B55-inhibiting Greatwall (Gwl)-endosulfine (ENSA) pathway is both necessary and sufficient for switch-like phosphorylations of mitotic substrates. Using purified components of the Gwl-ENSA pathway in a reconstituted system, we found a sharp Cdk1 threshold for phosphorylation of a luminescent mitotic substrate. The Cdk1 threshold to induce mitotic phosphorylation is distinctly higher than the Cdk1 threshold required to maintain these phosphorylations-evidence for bistability. A combination of mathematical modeling and biochemical reconstitution show that the bistable behavior of the Gwl-ENSA pathway emerges from its mutual antagonism with PP2A:B55. Our results demonstrate that two interlinked bistable mechanisms provide a robust solution for irreversible and switch-like mitotic entry. |
| spellingShingle | Mochida, S Rata, S Hino, H Nagai, T Novák, B Two bistable switches govern M phase entry |
| title | Two bistable switches govern M phase entry |
| title_full | Two bistable switches govern M phase entry |
| title_fullStr | Two bistable switches govern M phase entry |
| title_full_unstemmed | Two bistable switches govern M phase entry |
| title_short | Two bistable switches govern M phase entry |
| title_sort | two bistable switches govern m phase entry |
| work_keys_str_mv | AT mochidas twobistableswitchesgovernmphaseentry AT ratas twobistableswitchesgovernmphaseentry AT hinoh twobistableswitchesgovernmphaseentry AT nagait twobistableswitchesgovernmphaseentry AT novakb twobistableswitchesgovernmphaseentry |