Dataset Information

Human Cdc14A phosphatase modulates the G2/M transition through Cdc25A and Cdc25B.

ABSTRACT: The Cdc14 family of serine-threonine phosphatases antagonizes CDK activity by reversing CDK-dependent phosphorylation events. It is well established that the yeast members of this family bring about the M/G1 transition. Budding yeast Cdc14 is essential for CDK inactivation at the end of mitosis and fission yeast Cdc14 homologue Flp1/Clp1 down-regulates Cdc25 to ensure the inactivation of mitotic CDK complexes to trigger cell division. However, the functions of human Cdc14 homologues remain poorly understood. Here we have tested the hypothesis that Cdc14A might regulate Cdc25 mitotic inducers in human cells. We found that increasing levels of Cdc14A delay entry into mitosis by inhibiting Cdk1-cyclin B1 activity. By contrast, lowering the levels of Cdc14A accelerates mitotic entry. Biochemical analyses revealed that Cdc14A acts through key Cdk1-cyclin B1 regulators. We observed that Cdc14A directly bound to and dephosphorylated Cdc25B, inhibiting its catalytic activity. Cdc14A also regulated the activity of Cdc25A at the G2/M transition. Our results indicate that Cdc14A phosphatase prevents premature activation of Cdk1 regulating Cdc25A and Cdc25B at the entry into mitosis.

SUBMITTER: Vazquez-Novelle MD

PROVIDER: S-EPMC3003353 | biostudies-other | 2010 Dec

REPOSITORIES: biostudies-other

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Human Cdc14A phosphatase modulates the G2/M transition through Cdc25A and Cdc25B.

Vázquez-Novelle María D MD Mailand Niels N Ovejero Sara S Bueno Avelino A Sacristán María P MP

The Journal of biological chemistry 20101018 52

The Cdc14 family of serine-threonine phosphatases antagonizes CDK activity by reversing CDK-dependent phosphorylation events. It is well established that the yeast members of this family bring about the M/G1 transition. Budding yeast Cdc14 is essential for CDK inactivation at the end of mitosis and fission yeast Cdc14 homologue Flp1/Clp1 down-regulates Cdc25 to ensure the inactivation of mitotic CDK complexes to trigger cell division. However, the functions of human Cdc14 homologues remain poorl ...[more]

PMID: 20956543

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Project description:Tyrosine phosphatases are often weaponized by bacteria colonizing mucosal barriers to manipulate host cell signal transduction pathways. Porphyromonas gingivalis is a periodontal pathogen and emerging oncopathogen which interferes with gingival epithelial cell proliferation and migration, and induces a partial epithelial mesenchymal transition. P. gingivalis produces two tyrosine phosphatases, and we show here that the low molecular weight tyrosine phosphatase, Ltp1, is secreted within gingival epithelial cells and translocates to the nucleus. An ltp1 mutant of P. gingivalis showed a diminished ability to induce epithelial cell migration and proliferation. Ltp1 was also required for the transcriptional upregulation of Regulator of Growth and Cell Cycle (RGCC), one of the most differentially expressed genes in epithelial cells resulting from P. gingivalis infection. A phosphoarray and siRNA showed that P. gingivalis controlled RGCC expression through Akt, which was activated by phosphorylation on S473. Akt activation is opposed by PTEN, and P. gingivalis decreased the amount of PTEN in epithelial cells. Ectopically expressed Ltp1 bound to PTEN, and reduced phosphorylation of PTEN at Y336 which controls proteasomal degradation. Ltp-1 induced loss of PTEN stability was prevented by chemical inhibition of the proteasome. Knockdown of RGCC suppressed upregulation of Zeb2 and mesenchymal markers by P. gingivalis. RGCC inhibition was also accompanied by a reduction in production of the proinflammatory cytokine IL-6 in response to P. gingivalis. Elevated IL-6 levels can contribute to periodontal destruction, and the ltp1 mutant of P. gingivalis incited less bone loss compared to the parental strain in a murine model of periodontal disease. These results show that P. gingivalis can deliver Ltp1 within gingival epithelial cells, and establish PTEN as the target for Ltp1 phosphatase activity. Disruption of the Akt1/RGCC signaling axis by Ltp1 facilitates P. gingivalis-induced increases in epithelial cell migration, proliferation, EMT and inflammatory cytokine production.

Project description:The phosphatase Cdc25A plays an important role in cell cycle regulation by dephosphorylating its substrates, such as cyclin-dependent kinases. In this study, we demonstrate that Cdc25A negatively regulates RIG-I-mediated antiviral signaling. We found that ectopic expression of Cdc25A in 293T cells inhibits the activation of beta interferon (IFN-?) induced by Sendai virus and poly(I·C), while knockdown of Cdc25A enhances the transcription of IFN-? stimulated by RNA virus infection. The inhibitory effect of Cdc25A on the antiviral immune response is mainly dependent on its phosphatase activity. Data from a luciferase assay indicated that Cdc25A can inhibit TBK1-mediated activation of IFN-?. Further analysis indicated that Cdc25A can interact with TBK1 and reduce the phosphorylation of TBK1 at S172, which in turn decreases the phosphorylation of its downstream substrate IRF3. Consistently, knockdown of Cdc25A upregulates the phosphorylation of both TBK1-S172 and IRF3 in Sendai virus-infected or TBK1-transfected 293T cells. In addition, we confirmed that Cdc25A can directly dephosphorylate TBK1-S172-p. These results demonstrate that Cdc25A inhibits the antiviral immune response by reducing the active form of TBK1. Using herpes simplex virus 1 (HSV-1) infection, an IFN-? reporter assay, and reverse transcription-quantitative PCR (RT-qPCR), we demonstrated that Cdc25A can also inhibit DNA virus-induced activation of IFN-?. Using a vesicular stomatitis virus (VSV) infection assay, we confirmed that Cdc25A can repress the RIG-I-like receptor (RLR)-mediated antiviral immune response and influence the antiviral status of cells. In conclusion, we demonstrate that Cdc25A negatively regulates the antiviral immune response by inhibiting TBK1 activity.IMPORTANCE The RLR-mediated antiviral immune response is critical for host defense against RNA virus infection. However, the detailed mechanism for balancing the RLR signaling pathway in host cells is not well understood. We found that the phosphatase Cdc25A negatively regulates the RNA virus-induced innate immune response. Our studies indicate that Cdc25A inhibits the RLR signaling pathway via its phosphatase activity. We demonstrated that Cdc25A reduces TBK1 activity and consequently restrains the activation of IFN-? transcription as well as the antiviral status of nearby cells. We showed that Cdc25A can also inhibit DNA virus-induced activation of IFN-?. Taken together, our findings uncover a novel function and mechanism for Cdc25A in regulating antiviral immune signaling. These findings reveal Cdc25A as an important negative regulator of antiviral immunity and demonstrate its role in maintaining host cell homeostasis following viral infection.

Dataset Information

Human Cdc14A phosphatase modulates the G2/M transition through Cdc25A and Cdc25B.

Publications

Human Cdc14A phosphatase modulates the G2/M transition through Cdc25A and Cdc25B.

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