TY - JOUR
T1 - Protein interactomes of protein phosphatase 2A B55 regulatory subunits reveal B55-mediated regulation of replication protein A under replication stress
AU - Wang, Feifei
AU - Zhu, Songli
AU - Fisher, Laura A.
AU - Wang, Weidong
AU - Oakley, Gregory G.
AU - Li, Chunling
AU - Peng, Aimin
N1 - Funding Information:
This work was supported by a National Institutes of Health grant R01CA172574 to A.P. We thank Drs. Xuan Liu (University of California Riverside), Kumagai and Dunphy (California Institute of Technology) for reagents. Microscopic analysis was performed at the UNMC Advanced Microscopy Core Facility, supported by the Nebraska Research Initiative, the Fred and Pamela Buffett Cancer Center Support Grant (P30CA036727), and an Institutional Development Award (IDeA) from the NIGMS of the NIH (P30GM106397).
Publisher Copyright:
© 2018 The Author(s).
PY - 2018/12/1
Y1 - 2018/12/1
N2 - The specific function of PP2A, a major serine/threonine phosphatase, is mediated by regulatory targeting subunits, such as members of the B55 family. Although implicated in cell division and other pathways, the specific substrates and functions of B55 targeting subunits are largely undefined. In this study we identified over 100 binding proteins of B55α and B55β in Xenopus egg extracts that are involved in metabolism, mitochondria function, molecular trafficking, cell division, cytoskeleton, DNA replication, DNA repair, and cell signaling. Among the B55α and B55β-associated proteins were numerous mitotic regulators, including many substrates of CDK1. Consistently, upregulation of B55α accelerated M-phase exit and inhibited M-phase entry. Moreover, specific substrates of CDK2, including factors of DNA replication and chromatin remodeling were identified within the interactomes of B55α and B55β, suggesting a role for these phosphatase subunits in DNA replication. In particular, we confirmed in human cells that B55α binds RPA and mediates the dephosphorylation of RPA2. The B55-RPA association is disrupted after replication stress, consistent with the induction of RPA2 phosphorylation. Thus, we report here a new mechanism that accounts for both how RPA phosphorylation is modulated by PP2A and how the phosphorylation of RPA2 is abruptly induced after replication stress.
AB - The specific function of PP2A, a major serine/threonine phosphatase, is mediated by regulatory targeting subunits, such as members of the B55 family. Although implicated in cell division and other pathways, the specific substrates and functions of B55 targeting subunits are largely undefined. In this study we identified over 100 binding proteins of B55α and B55β in Xenopus egg extracts that are involved in metabolism, mitochondria function, molecular trafficking, cell division, cytoskeleton, DNA replication, DNA repair, and cell signaling. Among the B55α and B55β-associated proteins were numerous mitotic regulators, including many substrates of CDK1. Consistently, upregulation of B55α accelerated M-phase exit and inhibited M-phase entry. Moreover, specific substrates of CDK2, including factors of DNA replication and chromatin remodeling were identified within the interactomes of B55α and B55β, suggesting a role for these phosphatase subunits in DNA replication. In particular, we confirmed in human cells that B55α binds RPA and mediates the dephosphorylation of RPA2. The B55-RPA association is disrupted after replication stress, consistent with the induction of RPA2 phosphorylation. Thus, we report here a new mechanism that accounts for both how RPA phosphorylation is modulated by PP2A and how the phosphorylation of RPA2 is abruptly induced after replication stress.
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U2 - 10.1038/s41598-018-21040-6
DO - 10.1038/s41598-018-21040-6
M3 - Article
C2 - 29422626
AN - SCOPUS:85041796952
VL - 8
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 2683
ER -