Stonyte V, Martín R, Segura-Peña D, Sekulić N, Lopez-Aviles S. Requirement of PP2A-B56
Par1 for the Stabilization of the CDK Inhibitor Rum1 and Activation of APC/C
Ste9 during Pre-Start G1 in S. pombe.
iScience 2020;
23:101063. [PMID:
32361273 PMCID:
PMC7195536 DOI:
10.1016/j.isci.2020.101063]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/15/2020] [Accepted: 04/09/2020] [Indexed: 11/30/2022] Open
Abstract
Exit from the cell cycle during the establishment of quiescence and upon cell differentiation requires the sustained inactivation of CDK complexes. Fission yeast cells deprived of nitrogen halt cell cycle progression in pre-Start G1, before becoming quiescent or undergoing sexual differentiation. The CDK inhibitor Rum1 and the APC/C activator Ste9 are fundamental for this arrest, but both are down-regulated by CDK complexes. Here, we show that PP2A-B56Par1 is instrumental for Rum1 stabilization and Ste9 activation. In the absence of PP2A-B56Par1, cells fail to accumulate Rum1, and this results in persistent CDK activity, Ste9 inactivation, retention of the mitotic cyclin Cdc13, and impaired withdrawal from the cell cycle during nitrogen starvation. Importantly, mutation of a putative B56 interacting motif in Rum1 recapitulates these defects. These results underscore the relevance of CDK-counteracting phosphatases in cell differentiation, establishment of the quiescent state, and escape from it in cancer cells.
PP2A-B56Par1 is required for cell-cycle arrest and mating upon nitrogen deprivation
Loss of Par1 impairs degradation of Cdc13 under nitrogen starvation
Absence of Par1 impedes proper dephosphorylation of Ste9 and accumulation of Rum1
Mutation of a Rum1 putative PP2A-B56 SLiM depicts similar defects as the loss Par1
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