PP2A inhibitors arrest G2/M transition through JNK/Sp1-dependent down-regulation of CDK1 and autophagy-dependent up-regulation of p21
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PROVIDER: PRJNA470810 | ENA |
REPOSITORIES: ENA
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Project description:Protein phosphatase 2A (PP2A) plays an important role in the control of the cell cycle. We previously reported that the PP2A inhibitors, cantharidin and okadaic acid (OA), efficiently repressed the growth of cancer cells. In the present study, we found that PP2A inhibitors arrested the cell cycle at the G2 phase through a mechanism that was dependent on the JNK pathway. Microarrays further showed that PP2A inhibitors induced expression changes in multiple genes that participate in cell cycle transition. To verify whether these expression changes were executed in a PP2A-dependent manner, we targeted the PP2A catalytic subunit (PP2Ac) using siRNA and evaluated gene expression with a microarray. After the cross comparison of these microarray data, we identified that CDK1 was potentially the same target when treated with either PP2A inhibitors or PP2Ac siRNA. In addition, we found that the down-regulation of CDK1 occurred in a JNK-dependent manner. Luciferase reporter gene assays demonstrated that repression of the transcription of CDK1 was executed through the JNK-dependent activation of the Sp1 transcription factor. By constructing deletion mutants of the CDK1 promoter and by using ChIP assays, we identified an element in the CDK1 promoter that responded to the JNK/Sp1 pathway after stimulation with PP2A inhibitors. Cantharidin and OA also up-regulated the expression of p21, an inhibitor of CDK1, via autophagy rather than PP2A/JNK pathway. Thus, this present study found that the PP2A/JNK/Sp1/CDK1 pathway and the autophagy/p21 pathway participated in G2/M cell cycle arrest triggered by PP2A inhibitors. Quality-checked RNAs were then transcribed with the First-Strand cDNA Synthesis Kit(Agilent)and their expression data obtained using Agilent 4×44 K Human Whole-Genome 60-mer oligonucleotide microarrays according to the protocols by the manufacturer.
2018-12-06 | GSE114288 | GEO
Project description: Not available
| S-EPMC4621904 | biostudies-literature
Project description:RAS-mediated human cell transformation requires inhibition of the tumor suppressor Protein Phosphatase 2A (PP2A). Both RAS and PP2A mediate their effects by phosphoregulation, but phosphoprotein targets and cellular processes in which RAS and PP2A activities converge in human cancers have not been systematically analyzed. Here, based on mass spectrometry phosphoproteome data we discover that phosphosites co-regulated by RAS and PP2A are enriched on proteins involved in epigenetic gene regulation. As examples, RAS and PP2A co-regulate the same phosphorylation sites on HDAC1/2, KDM1A, MTA1/2, RNF168 and TP53BP1. Mechanistically, we validate co-regulation of NuRD chromatin repressor complex by RAS and PP2A. Consistent with their known synergistic effects in cancer, RAS activation and PP2A inhibition resulted in epigenetic reporter de-repression and activation of oncogenic transcription. Notably, transcriptional de-repression by PP2A inhibition was associated with increased euchromatin and decrease in global DNA methylation. Further, targeting of RAS- and PP2A-regulated epigenetic proteins decreased viability of KRAS-mutant human lung cancer cells. Collectively the results indicate that epigenetic protein complexes involved in oncogenic gene expression constitute a significant point of convergence for RAS hyperactivity and PP2A inhibition in cancer. Further, this work provides a resource for future studies focusing on phosphoregulation as a previously unappreciated layer of regulation of epigenetic gene regulation in cancer, and in other RAS/PP2A-regulated cellular processes.
2023-02-06 | GSE220592 | GEO
Project description:RAS-mediated human cell transformation requires inhibition of the tumor suppressor Protein Phosphatase 2A (PP2A). Both RAS and PP2A mediate their effects by phosphoregulation, but phosphoprotein targets and cellular processes in which RAS and PP2A activities converge in human cancers have not been systematically analyzed. Here, based on mass spectrometry phosphoproteome data we discover that phosphosites co-regulated by RAS and PP2A are enriched on proteins involved in epigenetic gene regulation. As examples, RAS and PP2A co-regulate the same phosphorylation sites on HDAC1/2, KDM1A, MTA1/2, RNF168 and TP53BP1. Mechanistically, we validate co-regulation of NuRD chromatin repressor complex by RAS and PP2A. Consistent with their known synergistic effects in cancer, RAS activation and PP2A inhibition resulted in epigenetic reporter de-repression and activation of oncogenic transcription. Notably, transcriptional de-repression by PP2A inhibition was associated with increased euchromatin and decrease in global DNA methylation. Further, targeting of RAS- and PP2A-regulated epigenetic proteins decreased viability of KRAS-mutant human lung cancer cells. Collectively the results indicate that epigenetic protein complexes involved in oncogenic gene expression constitute a significant point of convergence for RAS hyperactivity and PP2A inhibition in cancer. Further, this work provides a resource for future studies focusing on phosphoregulation as a previously unappreciated layer of regulation of epigenetic gene regulation in cancer, and in other RAS/PP2A-regulated cellular processes.
2023-02-06 | GSE220591 | GEO
Project description:RAS-mediated human cell transformation requires inhibition of the tumor suppressor Protein Phosphatase 2A (PP2A). Both RAS and PP2A mediate their effects by phosphoregulation, but phosphoprotein targets and cellular processes in which RAS and PP2A activities converge in human cancers have not been systematically analyzed. Here, based on mass spectrometry phosphoproteome data we discover that phosphosites co-regulated by RAS and PP2A are enriched on proteins involved in epigenetic gene regulation. As examples, RAS and PP2A co-regulate the same phosphorylation sites on HDAC1/2, KDM1A, MTA1/2, RNF168 and TP53BP1. Mechanistically, we validate co-regulation of NuRD chromatin repressor complex by RAS and PP2A. Consistent with their known synergistic effects in cancer, RAS activation and PP2A inhibition resulted in epigenetic reporter de-repression and activation of oncogenic transcription. Notably, transcriptional de-repression by PP2A inhibition was associated with increased euchromatin and decrease in global DNA methylation. Further, targeting of RAS- and PP2A-regulated epigenetic proteins decreased viability of KRAS-mutant human lung cancer cells. Collectively the results indicate that epigenetic protein complexes involved in oncogenic gene expression constitute a significant point of convergence for RAS hyperactivity and PP2A inhibition in cancer. Further, this work provides a resource for future studies focusing on phosphoregulation as a previously unappreciated layer of regulation of epigenetic gene regulation in cancer, and in other RAS/PP2A-regulated cellular processes.
2023-02-06 | GSE220590 | GEO
Project description:Analysis of gene expression across the cell cycle from wild type cells, and cells expressing alleles of Yox1, Yhp1, Hcm1, and Tos4 that cannot be phosphorylated by Cdk1. Expression of S-phase and M/G1 transcripts are downregulated when phosphorylation of these factors is blocked, demonstrating that Cdk1 promotes expression of late cell cycle genes. These experiments are two-color hybridizations of RNA isolated from synchronized wild type (WT) or phosphomutant (4P) cells, compared to RNA from asyncrhonous wild type cells in mid-log phase. Wild type and mutant cells were synchronized in G1 phase, released into the cell cycle and samples collected at 15 minute intervals. Each time course was carried out in duplicate, the replicate experiment was performed as a dye swap.
2014-04-10 | E-GEOD-55121 | biostudies-arrayexpress
Project description:Analysis of gene expression across the cell cycle from wild type cells, and cells expressing alleles of Yox1, Yhp1, Hcm1, and Tos4 that cannot be phosphorylated by Cdk1. Expression of S-phase and M/G1 transcripts are downregulated when phosphorylation of these factors is blocked, demonstrating that Cdk1 promotes expression of late cell cycle genes.
2014-04-10 | GSE55121 | GEO
Project description:In this study, we found that in ES cells the majority of Cdk1 substrates are localized on chromatin. Cdk1 phosphorylates a large number of proteins involved in epigenetic regulation, including writers and erasers of all major histone marks. High levels of Cdk1 in ES cells phosphorylate and partially inactivate Dot1l, the histone H3 lysine 79 methyltransferase responsible for placing activating H3K79 marks on gene bodies. Decrease of Cdk1 activity during ES cell differentiation de-represses Dot1l, thereby allowing coordinated expression of differentiation genes. These analyses indicate that Cdk1 functions to maintain the epigenetic identity of ES cells.
2020-04-04 | GSE134645 | GEO
Project description:Protein phosphatase 2A (PP2A) is a family of conserved serine/threonine phosphatases involved in several essential aspects of cell growth and proliferation. PP2ACdc55 phosphatase has been extensively related to cell cycle events in budding yeast, however few PP2ACdc55 substrates have been identified. Here, we performed a quantitative mass spectrometry approach to reveal new substrates of PP2ACdc55 phosphatase and new PP2A related processes in mitotic arrested cells. We identified 626 potential PP2ACdc55 substrates involved in a broad range of mitotic processes. As expected, several hyperphosphorylated proteins corresponded to Cdk1-dependent substrates, although other kinases’ consensus motifs were also enriched in our dataset, suggesting that PP2ACdc55 counteracts and regulates other kinases different than Cdk1. Indeed, Pkc1 and Cla4 kinases emerged as novel nodes of PP2ACdc55 regulation, highlighting a major role of PP2ACdc55 in membrane trafficking and cytokinesis, gene ontology terms significantly enriched in the PP2ACdc55-dependent phosphoproteome. In addition, we validated two new PP2ACdc55 substrates involved in early and late anaphase pathways, Slk19 and Lte1; and we also validated Zeo1, and other potential substrates, through protein interaction experiments. Finally, we performed docking models of Cdc55 and its substrate Mob1. We found that the predominant interface on Cdc55 is mediated by a protruding loop consisting of residues 84-90, thus highlighting the relevance of these aminoacids for substrate interaction.
2018-04-16 | PXD007613 | Pride
Project description:We evaluated the effects of suppressing MAP4K4 on transcriptome and YAP1 pathway based on the observation that partial suppression of MAP4K4 leads to transformation through activation of YAP1. Mutations and deletions involving subunits of the serine-threonine phosphatase PP2A occur in a broad range of human cancers, and partial loss of PP2A function contributes to cell transformation. In particular, displacement of regulatory B subunits by the viral oncoprotein SV40 small-t antigen (ST) or mutation or deletion of PP2A subunits alters the abundance and types of PP2A complexes in cells and induces cell transformation in human cells. Here we show that ST not only displaces common PP2A B subunits but also promotes PP2A A-C subunit interactions with a set of alternative B subunits (B’’’, striatins) that are components of the Striatin-interacting phosphatase and kinase (STRIPAK) complex. We found that members of the STRIPAK complex are required for ST-PP2A induced cell transformation. PP2A interacts with and dephosphorylates the STRIPAK-associated kinase MAP4K4, which induces cell transformation in part through the regulation of the Hippo pathway effector YAP1. These observations identify an unanticipated role of MAP4K4 in transformation and show that the STRIPAK complex plays a key role in defining PP2A specificity and activity.
2019-12-01 | GSE118272 | GEO