Regulation of PP2A, PP4, and PP6 holoenzyme assembly by carboxyl-terminal methylation

The family of Phosphoprotein Phosphatases (PPPs) is responsible for most cellular serine and threonine dephosphorylation. PPPs achieve substrate specificity and selectivity by forming multimeric holoenzymes. PPP holoenzyme assembly is tightly controlled, and changes in the cellular repertoire of PPPs are linked to human disease, including cancer and neurodegeneration. For PP2A, PP4, and PP6, holoenzyme formation is in part regulated by carboxyl (C)-terminal methyl-esterification (often referred to as methylation). Here, we use mass spectrometry-based proteomics, methylation-ablating mutations, and genome editing to elucidate the role of C-terminal methylation on PP2A, PP4, and PP6 holoenzyme assembly. We find that the catalytic subunits of PP2A, PP4, and PP6 are frequently methylated in cancer cells and that deletion of the C-terminal leucine faithfully recapitulates loss of methylation. We observe that loss of PP2A methylation consistently reduced B55, B56, and B72 regulatory subunit binding in cancer and non-transformed cell lines. However, Striatin subunit binding is only affected in non-transformed cells. For PP4, we find that PP4R1 and PP4R3β bind in a methylation-dependent manner. Intriguingly, loss of methylation does not affect PP6 holoenzymes. Our analyses demonstrate in an unbiased, comprehensive, and isoform-specific manner the crucial regulatory function of endogenous PPP methylation in transformed and non-transformed cell lines.

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Regulation of PP2A, PP4, and PP6 holoenzyme assembly by carboxyl-terminal methylation

Scientific Reports ◽

10.1038/s41598-021-02456-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Scott P. Lyons ◽

Elora C. Greiner ◽

Lauren E. Cressey ◽

Mark E. Adamo ◽

Arminja N. Kettenbach

Keyword(s):

Cell Lines ◽

Regulatory Subunit ◽

Regulatory Function ◽

Dependent Manner ◽

Catalytic Subunits ◽

Transformed Cell ◽

The Family ◽

Carboxyl Terminal ◽

Transformed Cell Lines

AbstractThe family of Phosphoprotein Phosphatases (PPPs) is responsible for most cellular serine and threonine dephosphorylation. PPPs achieve substrate specificity and selectivity by forming multimeric holoenzymes. PPP holoenzyme assembly is tightly controlled, and changes in the cellular repertoire of PPPs are linked to human disease, including cancer and neurodegeneration. For PP2A, PP4, and PP6, holoenzyme formation is in part regulated by carboxyl (C)-terminal methyl-esterification (often referred to as “methylation”). Here, we use mass spectrometry-based proteomics, methylation-ablating mutations, and genome editing to elucidate the role of C-terminal methylation on PP2A, PP4, and PP6 holoenzyme assembly. We find that the catalytic subunits of PP2A, PP4, and PP6 are frequently methylated in cancer cells and that deletion of the C-terminal leucine faithfully recapitulates loss of methylation. We observe that loss of PP2A methylation consistently reduced B55, B56, and B72 regulatory subunit binding in cancer and non-transformed cell lines. However, Striatin subunit binding is only affected in non-transformed cells. For PP4, we find that PP4R1 and PP4R3β bind in a methylation-dependent manner. Intriguingly, loss of methylation does not affect PP6 holoenzymes. Our analyses demonstrate in an unbiased, comprehensive, and isoform-specific manner the crucial regulatory function of endogenous PPP methylation in transformed and non-transformed cell lines.

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Circ_0000215 Exerts Oncogenic Function in Nasopharyngeal Carcinoma by Targeting miR-512-5p

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.688873 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xinping Chen ◽

Weihua Xu ◽

Zhichao Ma ◽

Juan Zhu ◽

Junjie Hu ◽

...

Keyword(s):

Nasopharyngeal Carcinoma ◽

Cell Lines ◽

Cell Counting ◽

Regulatory Subunit ◽

Luciferase Reporter ◽

Regulatory Function ◽

Migration And Invasion ◽

Circular Rnas

Background: Increasing circular RNAs (circRNAs) are reported to participate in cancer progression. Nonetheless, the role of circRNAs in nasopharyngeal carcinoma (NPC) has not been fully clarified. This work is aimed to probe the role of circ_0000215 in NPC.Methods: Circ_0000215 expression in NPC tissues and cell lines was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) assay, 5-bromo-2′-deoxyuridine (BrdU) assay, scratch healing assay and Transwell experiment were executed to investigate the regulatory function of circ_0000215 on the proliferation, migration and invasion of NPC cells. RNA immunoprecipitation (RIP), pull-down and dual-luciferase reporter experiments were utilized to determine the binding relationship between circ_0000215 and miR-512-5p, and between miR-512-5p and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) 3′UTR. The effects of circ_0000215 on NPC growth and metastasis in vivo were examined with nude mice model. Western blot was applied to detect the regulatory effects of circ_0000215 and miR-512-5p on PIK3R1 expression.Results: Circ_0000215 was overexpressed in NPC tissues and cell lines. The functional experiments confirmed that knockdown of circ_0000215 impeded the growth and metastasis of NPC cells in vitro and in vivo. Additionally, circ_0000215 could also work as a molecular sponge to repress miR-512-5p expression. PIK3R1 was validated as a target gene of miR-512-5p, and circ_0000215 could increase the expression level of PIK3R1 in NPC cells via suppressing miR-512-5p.Conclusion: Circ_0000215 is overexpressed in NPC and exerts oncogenic effects in NPC through regulating miR-512-5p/PIK3R1 axis.

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Jasplakinolide Induces Apoptosis in Various Transformed Cell Lines by a Caspase-3-Like Protease-Dependent Pathway

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.7.6.947-952.2000 ◽

2000 ◽

Vol 7 (6) ◽

pp. 947-952 ◽

Cited By ~ 76

Author(s):

Chikako Odaka ◽

Miranda L. Sanders ◽

Phillip Crews

Keyword(s):

T Cells ◽

Cell Death ◽

Cell Lines ◽

Caspase 3 ◽

Dependent Manner ◽

Jurkat T Cells ◽

Transformed Cell ◽

Induced Apoptosis ◽

Transformed Cell Lines ◽

Dependent Pathway

ABSTRACT To clarify the mechanisms underlying the antiproliferative effects of jasplakinolide, a cyclic depsipeptide from marine sponges, we examined whether jasplakinolide induces apoptosis in a variety of transformed and nontransformed cells. Jasplakinolide inhibited proliferation of human Jurkat T cells, resulting in cell death. This was accompanied by chromatin condensation and DNA cleavage at the linker regions between the nucleosomes. When caspase-3-like activity in the cytosolic extracts of Jurkat T cells was examined with a fluorescent substrate, DEVD-MAC (N-acetyl-Asp-Glu-Val-Asp-4-methyl-coumaryl-7-amide), the activity in the cells treated with jasplakinolide was remarkably increased in a time-dependent manner. Pretreatment of Jurkat T cells with the caspase inhibitor zVAD [benzyloxycarbonyl(Cbz)-Val-Ala-β-Asp(OMe)-fluoromethylketone] or DEVD-CHO (N-acetyl-Asp-Glu-Val-Asp-1-aldehyde) prevented the induction of apoptosis by jasplakinolide. Moreover, exposure of various murine transformed cell lines to jasplakinolide resulted in cell death, which was inhibited by zVAD. Although it has been well established that murine immature thymocytes are sensitive to apoptosis when exposed to various apoptotic stimuli, these cells as well as mature T lymphocytes were resistant to jasplakinolide-induced apoptosis. The results suggest that jasplakinolide induces apoptotic cell death through a caspase-3-like protease-dependent pathway. Another important outcome is that transformed cell lines were more susceptible to jasplakinolide-induced apoptosis than normal nontransformed cells.

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Abstract C68: Using a chemical genetic approach to define the role of CDK2 in normal and transformed cell lines

10.1158/0008-5472.fbcr09-c68 ◽

2009 ◽

Author(s):

Noelle E. Huskey ◽

Dai Horiuchi ◽

Leonard Kusdra ◽

Chao Zhang ◽

Kevan Shokat ◽

...

Keyword(s):

Cell Lines ◽

Genetic Approach ◽

Transformed Cell ◽

Chemical Genetic ◽

Transformed Cell Lines

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PRKAR2A deficiency protects mice from experimental colitis by increasing IFN-stimulated gene expression and modulating the intestinal microbiota

Mucosal Immunology ◽

10.1038/s41385-021-00426-2 ◽

2021 ◽

Author(s):

Lumin Wei ◽

Rongjing Zhang ◽

Jinzhao Zhang ◽

Juanjuan Li ◽

Deping Kong ◽

...

Keyword(s):

Experimental Colitis ◽

Regulatory Subunit ◽

Protective Effects ◽

Intestinal Epithelial ◽

Catalytic Subunits ◽

Regulatory Subunits ◽

Pka Regulatory Subunit ◽

Cross Fostering ◽

Specific Deletion

AbstractProtein kinase A (PKA) plays an important role in regulating inflammation via its catalytic subunits. Recently, PKA regulatory subunits have been reported to directly modulate some signaling pathways and alleviate inflammation. However, the role of PKA regulatory subunits in colonic inflammation remains unclear. Therefore, we conducted this study to investigate the role of the PKA regulatory subunit PRKAR2A in colitis. We observed that PRKAR2A deficiency protected mice from dextran sulfate sodium (DSS)-induced experimental colitis. Our experiments revealed that the intestinal epithelial cell-specific deletion of Prkar2a contributed to this protection. Mechanistically, the loss of PRKAR2A in Prkar2a−/− mice resulted in an increased IFN-stimulated gene (ISG) expression and altered gut microbiota. Inhibition of ISGs partially reversed the protective effects against DSS-induced colitis in Prkar2a−/− mice. Antibiotic treatment and cross-fostering experiments demonstrated that the protection against DSS-induced colitis in Prkar2a−/− mice was largely dependent on the gut microflora. Altogether, our work demonstrates a previously unidentified function of PRKAR2A in promoting DSS-induced colitis.

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