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Plk4 Is a Novel Substrate of Protein Phosphatase 5. Int J Mol Sci 2023; 24:ijms24032033. [PMID: 36768356 PMCID: PMC9917060 DOI: 10.3390/ijms24032033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
The conserved Ser/Thr protein phosphatase 5 (PP5) is involved in the regulation of key cellular processes, including DNA damage repair and cell division in eukaryotes. As a co-chaperone of Hsp90, PP5 has been shown to modulate the maturation and activity of numerous oncogenic kinases. Here, we identify a novel substrate of PP5, the Polo-like kinase 4 (Plk4), which is the master regulator of centriole duplication in animal cells. We show that PP5 specifically interacts with Plk4, and is able to dephosphorylate the kinase in vitro and in vivo, which affects the interaction of Plk4 with its partner proteins. In addition, we provide evidence that PP5 and Plk4 co-localize to the centrosomes in Drosophila embryos and cultured cells. We demonstrate that PP5 is not essential; the null mutant flies are viable without a severe mitotic phenotype; however, its loss significantly reduces the fertility of the animals. Our results suggest that PP5 is a novel regulator of the Plk4 kinase in Drosophila.
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Stubbs FE, Flynn BP, Rivers CA, Birnie MT, Herman A, Swinstead EE, Baek S, Fang H, Temple J, Carroll JS, Hager GL, Lightman SL, Conway-Campbell BL. Identification of a novel GR-ARID1a-P53BP1 protein complex involved in DNA damage repair and cell cycle regulation. Oncogene 2022; 41:5347-5360. [PMID: 36344675 PMCID: PMC9734058 DOI: 10.1038/s41388-022-02516-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 10/02/2022] [Accepted: 10/17/2022] [Indexed: 11/09/2022]
Abstract
ARID1a (BAF250), a component of human SWI/SNF chromatin remodeling complexes, is frequently mutated across numerous cancers, and its loss of function has been putatively linked to glucocorticoid resistance. Here, we interrogate the impact of siRNA knockdown of ARID1a compared to a functional interference approach in the HeLa human cervical cancer cell line. We report that ARID1a knockdown resulted in a significant global decrease in chromatin accessibility in ATAC-Seq analysis, as well as affecting a subset of genome-wide GR binding sites determined by analyzing GR ChIP-Seq data. Interestingly, the specific effects on gene expression were limited to a relatively small subset of glucocorticoid-regulated genes, notably those involved in cell cycle regulation and DNA repair. The vast majority of glucocorticoid-regulated genes were largely unaffected by ARID1a knockdown or functional interference, consistent with a more specific role for ARID1a in glucocorticoid function than previously speculated. Using liquid chromatography-mass spectrometry, we have identified a chromatin-associated protein complex comprising GR, ARID1a, and several DNA damage repair proteins including P53 binding protein 1 (P53BP1), Poly(ADP-Ribose) Polymerase 1 (PARP1), DNA damage-binding protein 1 (DDB1), DNA mismatch repair protein MSH6 and splicing factor proline and glutamine-rich protein (SFPQ), as well as the histone acetyltransferase KAT7, an epigenetic regulator of steroid-dependent transcription, DNA damage repair and cell cycle regulation. Not only was this protein complex ablated with both ARID1a knockdown and functional interference, but spontaneously arising DNA damage was also found to accumulate in a manner consistent with impaired DNA damage repair mechanisms. Recovery from dexamethasone-dependent cell cycle arrest was also significantly impaired. Taken together, our data demonstrate that although glucocorticoids can still promote cell cycle arrest in the absence of ARID1a, the purpose of this arrest to allow time for DNA damage repair is hindered.
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Affiliation(s)
- Felicity E Stubbs
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
- Laboratory of Receptor Biology and Gene Expression, The National Cancer Institute, US National Institutes of Health, 41 Medlars Drive, Bethesda, MD, 20892, USA
| | - Benjamin P Flynn
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Caroline A Rivers
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Matthew T Birnie
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Andrew Herman
- Flow Cytometry Facility, Faculty of Life Sciences, School of Cellular & Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Erin E Swinstead
- Laboratory of Receptor Biology and Gene Expression, The National Cancer Institute, US National Institutes of Health, 41 Medlars Drive, Bethesda, MD, 20892, USA
| | - Songjoon Baek
- Laboratory of Receptor Biology and Gene Expression, The National Cancer Institute, US National Institutes of Health, 41 Medlars Drive, Bethesda, MD, 20892, USA
| | - Hai Fang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jillian Temple
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Jason S Carroll
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, The National Cancer Institute, US National Institutes of Health, 41 Medlars Drive, Bethesda, MD, 20892, USA
| | - Stafford L Lightman
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Becky L Conway-Campbell
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Translational Health Sciences, Faculty of Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK.
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Therapeutic targeting of ATR in alveolar rhabdomyosarcoma. Nat Commun 2022; 13:4297. [PMID: 35879366 PMCID: PMC9314382 DOI: 10.1038/s41467-022-32023-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 07/11/2022] [Indexed: 11/08/2022] Open
Abstract
Despite advances in multi-modal treatment approaches, clinical outcomes of patients suffering from PAX3-FOXO1 fusion oncogene-expressing alveolar rhabdomyosarcoma (ARMS) remain dismal. Here we show that PAX3-FOXO1-expressing ARMS cells are sensitive to pharmacological ataxia telangiectasia and Rad3 related protein (ATR) inhibition. Expression of PAX3-FOXO1 in muscle progenitor cells is not only sufficient to increase sensitivity to ATR inhibition, but PAX3-FOXO1-expressing rhabdomyosarcoma cells also exhibit increased sensitivity to structurally diverse inhibitors of ATR. Mechanistically, ATR inhibition leads to replication stress exacerbation, decreased BRCA1 phosphorylation and reduced homologous recombination-mediated DNA repair pathway activity. Consequently, ATR inhibitor treatment increases sensitivity of ARMS cells to PARP1 inhibition in vitro, and combined treatment with ATR and PARP1 inhibitors induces complete regression of primary patient-derived ARMS xenografts in vivo. Lastly, a genome-wide CRISPR activation screen (CRISPRa) in combination with transcriptional analyses of ATR inhibitor resistant ARMS cells identifies the RAS-MAPK pathway and its targets, the FOS gene family, as inducers of resistance to ATR inhibition. Our findings provide a rationale for upcoming biomarker-driven clinical trials of ATR inhibitors in patients suffering from ARMS.
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Preferential Involvement of BRCA1/BARD1, Not Tip60/Fe65, in DNA Double-Strand Break Repair in Presenilin-1 P117L Alzheimer Models. Neural Plast 2022; 2022:3172861. [PMID: 35237315 PMCID: PMC8885292 DOI: 10.1155/2022/3172861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/11/2022] [Accepted: 01/28/2022] [Indexed: 11/20/2022] Open
Abstract
Recently, we showed that DNA double-strand breaks (DSBs) are increased by the Aβ42-amyloid peptide and decreased by all-trans retinoic acid (RA) in SH-SY5Y cells and C57BL/6J mice. The present work was aimed at investigating DSBs in cells and murine models of Alzheimer's disease carrying the preseniline-1 (PS1) P117L mutation. We observed that DSBs could hardly decrease following RA treatment in the mutated cells compared to the wild-type cells. The activation of the amyloidogenic pathway is proposed in the former case as Aβ42- and RA-dependent DSBs changes were reproduced by an α-secretase and a γ-secretase inhibitions, respectively. Unexpectedly, the PS1 P117L cells showed lower DSB levels than the controls. As the DSB repair proteins Tip60 and Fe65 were less expressed in the mutated cell nuclei, they do not appear to contribute to this difference. On the contrary, full-length BRCA1 and BARD1 proteins were significantly increased in the chromatin compartment of the mutated cells, suggesting that they decrease DSBs in the pathological situation. These Western blot data were corroborated by in situ proximity ligation assays: the numbers of BRCA1-BARD1, not of Fe65-Tip60 heterodimers, were increased only in the mutated cell nuclei. RA also enhanced the expression of BARD1 and of the 90 kDa BRCA1 isoform. The increased BRCA1 expression in the mutated cells can be related to the enhanced difficulty to inhibit this pathway by BRCA1 siRNA in these cells. Overall, our study suggests that at earlier stages of the disease, similarly to PS1 P117L cells, a compensatory mechanism exists that decreases DSB levels via an activation of the BRCA1/BARD1 pathway. This supports the importance of this pathway in neuroprotection against Alzheimer's disease.
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Russo LC, Farias JO, Forti FL. DUSP3 maintains genomic stability and cell proliferation by modulating NER pathway and cell cycle regulatory proteins. Cell Cycle 2020; 19:1545-1561. [PMID: 32380926 DOI: 10.1080/15384101.2020.1762043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The DUSP3 phosphatase regulates cell cycle, proliferation, apoptosis and senescence of different cell types, lately shown as a mediator of DNA repair processes. This work evaluated the impact of DUSP3 loss of function (lof) on DNA repair-proficient fibroblasts (MRC-5), NER-deficient cell lines (XPA and XPC) and translesion DNA synthesis (TLS)-deficient cells (XPV), after UV-radiation stress. The levels of DNA strand breaks, CPDs and 6-4-PPs have accumulated over time in all cells under DUSP3 lof, with a significant increase in NER-deficient lines. The inefficient repair of these lesions increased sub-G1 population of XPA and XPC cells 24 hours after UV treatment, notably marked by DUSP3 lof, which is associated with a reduced cell population in G1, S and G2/M phases. It was also detected an increase in S and G2/M populations of XPV and MRC-5 cells after UV-radiation exposure, which was slightly attenuated by DUSP3 lof due to a discrete increase in sub-G1 cells. The cell cycle progression was accompanied by changes in the levels of the main Cyclins (A1, B1, D1 or E1), CDKs (1, 2, 4 or 6), and the p21 Cip1 inhibitor, in a DUSP3-dependent manner. DUSP3 lof affected the proliferation of MRC-5 and XPA cells, with marked worsening of the XP phenotype after UV radiation. This work highlights the roles of DUSP3 in DNA repair fitness and in the fine control of regulatory proteins of cell cycle, essential mechanisms to maintenance of genomic stability.
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Affiliation(s)
- Lilian Cristina Russo
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
| | - Jessica Oliveira Farias
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
| | - Fabio Luis Forti
- Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of Sao Paulo , São Paulo-SP, Brazil
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Cell Cycle and DNA Repair Regulation in the Damage Response: Protein Phosphatases Take Over the Reins. Int J Mol Sci 2020; 21:ijms21020446. [PMID: 31936707 PMCID: PMC7014277 DOI: 10.3390/ijms21020446] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 12/14/2022] Open
Abstract
Cells are constantly suffering genotoxic stresses that affect the integrity of our genetic material. Genotoxic insults must be repaired to avoid the loss or inappropriate transmission of the genetic information, a situation that could lead to the appearance of developmental abnormalities and tumorigenesis. To combat this threat, eukaryotic cells have evolved a set of sophisticated molecular mechanisms that are collectively known as the DNA damage response (DDR). This surveillance system controls several aspects of the cellular response, including the detection of lesions, a temporary cell cycle arrest, and the repair of the broken DNA. While the regulation of the DDR by numerous kinases has been well documented over the last decade, the complex roles of protein dephosphorylation have only recently begun to be investigated. Here, we review recent progress in the characterization of DDR-related protein phosphatases during the response to a DNA lesion, focusing mainly on their ability to modulate the DNA damage checkpoint and the repair of the damaged DNA. We also discuss their protein composition and structure, target specificity, and biochemical regulation along the different stages encompassed in the DDR. The compilation of this information will allow us to better comprehend the physiological significance of protein dephosphorylation in the maintenance of genome integrity and cell viability in response to genotoxic stress.
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The protein phosphatase gene MaPpt1 acts as a programmer of microcycle conidiation and a negative regulator of UV-B tolerance in Metarhizium acridum. Appl Microbiol Biotechnol 2019; 103:1351-1362. [DOI: 10.1007/s00253-018-9567-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 12/18/2022]
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Huang CY, Hsieh FS, Wang CY, Chen LJ, Chang SS, Tsai MH, Hung MH, Kuo CW, Shih CT, Chao TI, Chen KF. Palbociclib enhances radiosensitivity of hepatocellular carcinoma and cholangiocarcinoma via inhibiting ataxia telangiectasia-mutated kinase-mediated DNA damage response. Eur J Cancer 2018; 102:10-22. [PMID: 30103095 DOI: 10.1016/j.ejca.2018.07.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 12/15/2022]
Abstract
AIM Palbociclib is an oral cyclin-dependent kinase 4/6 inhibitor, which is efficacious in treating breast cancer. Currently, there are numerous active clinical trials testing palbociclib alone or in combination with other medications for treating various types of malignancies. Here, we evaluated the anti-cancer effect of palbociclib in combination with radiation therapy (RT) for treating human hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) and addressed the molecular mechanism behind the combination therapy. METHODS Immunofluorescence staining of γH2AX or 53BP1 was used to determine the effect of palbociclib on double-strand break (DSB) repair. Clonogenic assays, sphere formation and cell death ELISA were performed to study the sensitising effect of palbociclib on radiation-induced cytotoxicity. Signal alteration in DSB repair pathways was examined by Western blot analysis. Finally, we evaluated the in vivo anti-cancer activity and the associated molecular events of the combination therapy in a preclinical HCC xenograft model. RESULTS Palbociclib affected the kinetics of DNA repair and enhanced the radiation sensitivity of HCC and CCA cells. Importantly, we found that palbociclib inhibits ataxia telangiectasia-mutated (ATM) kinase, the key upstream kinase responding to RT-induced DSBs. Furthermore, we showed that the inhibitory effect of palbociclib on RT-induced ATM kinase activation is mediated by protein phosphatase 5 (PP5). Both in vitro and in vivo investigations revealed that the inhibition of the PP5-ATM axis by palbociclib after DNA damage is responsible for the synergism between palbociclib and RT. CONCLUSION Our findings provide a novel combination strategy against liver cancer cells. Clinical trials using palbociclib as an adjuvant in RT are warranted.
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Affiliation(s)
- Chao-Yuan Huang
- Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Imaging and Radiological Technology, Yuanpei University, Hsinchu, Taiwan
| | - Feng-Shu Hsieh
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.
| | - Cheng-Yi Wang
- Department of Internal Medicine, Cardinal Tien Hospital, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Li-Ju Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Shih-Shin Chang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Ming-Hsien Tsai
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Man-Hsin Hung
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chiung-Wen Kuo
- Department of Medical Imaging and Radiological Technology, Yuanpei University, Hsinchu, Taiwan
| | - Chi-Ting Shih
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | | | - Kuen-Feng Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan; National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital, Taipei, Taiwan.
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Cusin I, Teixeira D, Zahn-Zabal M, Rech de Laval V, Gleizes A, Viassolo V, Chappuis PO, Hutter P, Bairoch A, Gaudet P. A new bioinformatics tool to help assess the significance of BRCA1 variants. Hum Genomics 2018; 12:36. [PMID: 29996917 PMCID: PMC6042458 DOI: 10.1186/s40246-018-0168-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/25/2018] [Indexed: 12/23/2022] Open
Abstract
Background Germline pathogenic variants in the breast cancer type 1 susceptibility gene BRCA1 are associated with a 60% lifetime risk for breast and ovarian cancer. This overall risk estimate is for all BRCA1 variants; obviously, not all variants confer the same risk of developing a disease. In cancer patients, loss of BRCA1 function in tumor tissue has been associated with an increased sensitivity to platinum agents and to poly-(ADP-ribose) polymerase (PARP) inhibitors. For clinical management of both at-risk individuals and cancer patients, it would be important that each identified genetic variant be associated with clinical significance. Unfortunately for the vast majority of variants, the clinical impact is unknown. The availability of results from studies assessing the impact of variants on protein function may provide insight of crucial importance. Results and conclusion We have collected, curated, and structured the molecular and cellular phenotypic impact of 3654 distinct BRCA1 variants. The data was modeled in triple format, using the variant as a subject, the studied function as the object, and a predicate describing the relation between the two. Each annotation is supported by a fully traceable evidence. The data was captured using standard ontologies to ensure consistency, and enhance searchability and interoperability. We have assessed the extent to which functional defects at the molecular and cellular levels correlate with the clinical interpretation of variants by ClinVar submitters. Approximately 30% of the ClinVar BRCA1 missense variants have some molecular or cellular assay available in the literature. Pathogenic variants (as assigned by ClinVar) have at least some significant functional defect in 94% of testable cases. For benign variants, 77% of ClinVar benign variants, for which neXtProt Cancer variant portal has data, shows either no or mild experimental functional defects. While this does not provide evidence for clinical interpretation of variants, it may provide some guidance for variants of unknown significance, in the absence of more reliable data. The neXtProt Cancer variant portal (https://www.nextprot.org/portals/breast-cancer) contains over 6300 observations at the molecular and/or cellular level for BRCA1 variants.
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Affiliation(s)
- Isabelle Cusin
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland
| | - Daniel Teixeira
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland
| | - Monique Zahn-Zabal
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland
| | - Valentine Rech de Laval
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland.,Department of Human Protein Sciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Anne Gleizes
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland
| | - Valeria Viassolo
- Oncogenetics and Cancer Prevention Unit, Division of Oncology, University Hospitals of Geneva, 1205, Geneva, Switzerland
| | - Pierre O Chappuis
- Oncogenetics and Cancer Prevention Unit, Division of Oncology, University Hospitals of Geneva, 1205, Geneva, Switzerland.,Division of Genetic Medicine, University Hospitals of Geneva, 1205, Geneva, Switzerland
| | - Pierre Hutter
- Sophia Genetics, Rue du Centre 172, 1025, Saint Sulpice, Switzerland
| | - Amos Bairoch
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland.,Department of Human Protein Sciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pascale Gaudet
- CALIPHO group, SIB Swiss Institute of Bioinformatics, 1211, Geneva 4, Switzerland. .,Department of Human Protein Sciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
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Chen YL, Hung MH, Chu PY, Chao TI, Tsai MH, Chen LJ, Hsiao YJ, Shih CT, Hsieh FS, Chen KF. Protein phosphatase 5 promotes hepatocarcinogenesis through interaction with AMP-activated protein kinase. Biochem Pharmacol 2017; 138:49-60. [DOI: 10.1016/j.bcp.2017.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 05/12/2017] [Indexed: 11/27/2022]
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Kim JY, Kim G, Lim SC, Choi HS. LPIN1 promotes epithelial cell transformation and mammary tumourigenesis via enhancing insulin receptor substrate 1 stability. Carcinogenesis 2016; 37:1199-1209. [PMID: 27729374 DOI: 10.1093/carcin/bgw104] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/25/2016] [Accepted: 10/10/2016] [Indexed: 02/07/2023] Open
Abstract
LPIN1 is a protein that exhibits dual functions as a phosphatidic acid phosphatase enzyme in regulation of triglyceride and glycerophospholipid metabolism and a transcriptional coregulator. Through unknown tumour-promoting mechanism, LPIN1 frequently observed in various human cancer cell lines controls main cellular processes involved in cancer progression. Here, we demonstrate that LPIN1 enhances the tumour-promoting function of insulin receptor substrate 1 (IRS1) by controlling IRS1 stability. LPIN1 interacts with IRS1 in an insulin growth factor-1-dependent signalling pathway and inhibits its serine phosphorylation, and thereby eliminating ubiquitin-dependent degradation of IRS1 via proteasomal and lysosomal pathways. Consequently, LPIN1 overexpression increases IRS1 abundance and enhances IRS1's ability to induce epithelial cell proliferation and mammary tumourigenesis. By contrast, depletion or inhibition of LPIN1 in breast cancer cells leads to a decreased IRS1 level, which subsequently inhibits the RAF1-mediated signalling pathway and AP-1 activity. In the syngeneic 4T1 breast cancer model, LPIN1 overexpression increased tumour development, whereas inhibition of LPIN1 and IRS1 suppressed it. Consistent with these observations, LPIN1 levels were positively correlated with IRS1 expression in human breast cancer. Thus, our results indicate a mechanism by which IRS1 expression is increased in breast cancer, and LPIN1 may be a promising drug target for anticancer therapy.
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Affiliation(s)
| | | | - Sung-Chul Lim
- Department of Pathology, School of Medicine, Chosun University, 309 Philmundaero, Dong-gu, Gwangju 61452, Republic of Korea
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BRCA1 affects protein phosphatase 6 signalling through its interaction with ANKRD28. Biochem J 2016; 473:949-60. [PMID: 27026398 DOI: 10.1042/bj20150797] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 02/04/2016] [Indexed: 11/17/2022]
Abstract
The tumour suppressor BRCA1 (breast and ovarian cancer-susceptibility gene 1) is implicated in several nuclear processes including DNA repair, transcription regulation and chromatin remodelling. BRCA1 also has some cytoplasmic functions including a pro-apoptotic activity. We identified ANKRD28 (ankyrin repeat domain 28) as a novel BRCA1-interacting protein in a yeast two-hybrid screen and confirmed this interaction by reciprocal immunoprecipitations of the two overexpressed proteins. Endogenous interaction between BRCA1 and ANKRD28 was also observed by co-immunoprecipitation and located in the cytoplasm by proximity ligation assay. The main site of interaction of ANKRD28 on BRCA1 is located in its intrinsically disordered scaffold central region. Whereas ANKRD28 silencing results in a destabilization of IκBε (inhibitor of nuclear factor κBε) through its activation of PP6 (protein phosphatase 6) co-regulator upon TNFα (tumour necrosis factor α) stimulation, BRCA1 overexpression stabilizes IκBε. A truncated form of BRCA1 that does not interact with ANKRD28 has no such effect. Our findings suggest that BRCA1 is a novel modulator of PP6 signalling via its interaction with ANKRD28. This new cytoplasmic process might participate in BRCA1 tumour-suppressor function.
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Wang J, Zhu J, Dong M, Yu H, Dai X, Li K. Inhibition of protein phosphatase 5 (PP5) suppresses survival and growth of colorectal cancer cells. Biotechnol Appl Biochem 2015; 62:621-7. [PMID: 25322973 DOI: 10.1002/bab.1308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 10/11/2014] [Indexed: 01/05/2023]
Abstract
Protein phosphatase 5 (PP5) is a unique member of the protein phosphatases family that functions in multiple signaling pathways involved in DNA damage, cell cycle control, cell growth, and apoptosis. Recent evidence indicated that PP5 may play a role in cancer progression. In this study, we aimed to examine the biological effect of PP5 on cell growth and apoptosis in human colorectal cancer (CRC). We first knocked down PP5 expression in RKO cells via a short hairpin RNA containing lentivirus system. Then, methylthiazoletetrazolium assay, colony formation assay, and flow cytometry analysis were performed. The proliferation and colony formation ability of RKO cells were remarkably suppressed in PP5-silenced groups, as compared with control groups. Moreover, downregulation of PP5 resulted in a significant G0/G1 phase cell cycle arrest and an induction of apoptosis. In all, these results demonstrated the importance of PP5 in CRC cell growth, and it might be used as a potential therapeutic target for the treatment of CRC.
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Affiliation(s)
- Jianwei Wang
- Department of Surgical Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Jinhui Zhu
- Department of Surgical Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Mingjun Dong
- Department of Anorectal Surgery, Ningbo Second Hospital, Ningbo, People's Republic of China
| | - Hua Yu
- Department of Anorectal Surgery, Ningbo Second Hospital, Ningbo, People's Republic of China
| | - Xiaoyu Dai
- Department of Anorectal Surgery, Ningbo Second Hospital, Ningbo, People's Republic of China
| | - Keqiang Li
- Clinical Research Center, Ningbo Second Hospital, Key Laboratory of Molecular Biology of Cancer, Ningbo, People's Republic of China
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Holme JA, Nyvold HE, Tat V, Arlt VM, Bhargava A, Gutzkow KB, Solhaug A, Låg M, Becher R, Schwarze PE, Ask K, Ekeren L, Øvrevik J. Mechanisms linked to differences in the mutagenic potential of 1,3-dinitropyrene and 1,8-dinitropyrene. Toxicol Rep 2014; 1:459-473. [PMID: 28962260 PMCID: PMC4547165 DOI: 10.1016/j.toxrep.2014.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/07/2014] [Accepted: 07/08/2014] [Indexed: 11/22/2022] Open
Abstract
This study explores and characterizes the toxicity of two closely related carcinogenic dinitro-pyrenes (DNPs), 1,3-DNP and 1,8-DNP, in human bronchial epithelial BEAS-2B cells and mouse hepatoma Hepa1c1c7 cells. Neither 1,3-DNP nor 1,8-DNP (3–30 μM) induced cell death in BEAS-2B cells. In Hepa1c1c7 cells only 1,3-DNP (10–30 μM) induced a mixture of apoptotic and necrotic cell death after 24 h. Both compounds increased the level of reactive oxygen species (ROS) in BEAS-2B as measured by CM-H2DCFDA-fluorescence. A corresponding increase in oxidative damage to DNA was revealed by the formamidopyrimidine-DNA glycosylase (fpg)-modified comet assay. Without fpg, DNP-induced DNA damage detected by the comet assay was only found in Hepa1c1c7 cells. Only 1,8-DNP formed DNA adduct measured by 32P-postlabelling. In Hepa1c1c cells, 1,8-DNP induced phosphorylation of H2AX (γH2AX) and p53 at a lower concentration than 1,3-DNP and there was no direct correlation between DNA damage/DNA damage response (DR) and induced cytotoxicity. On the other hand, 1,3-DNP-induced apoptosis was inhibited by pifithrin-α, an inhibitor of p53 transcriptional activity. Furthermore, 1,3-DNP triggered an unfolded protein response (UPR), as measured by an increased expression of CHOP, ATF4 and XBP1. Thus, other types of damage possibly linked to endoplasmic reticulum (ER)-stress and/or UPR could be involved in the induced apoptosis. Our results suggest that the stronger carcinogenic potency of 1,8-DNP compared to 1,3-DNP is linked to its higher genotoxic effects. This in combination with its lower potency to induce cell death may increase the probability of causing mutations.
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Key Words
- 1,3-DNP, 1,3-dinitropyrene
- 1,3-Dinitropyrene
- 1,8-DNP, 1,8-dinitropyrene
- 1,8-Dinitropyrene
- 1-NP, 1-nitropyrene
- 3-NBA, 3-nitrobenzanthrone
- AhR, aromatic hydrocarbon receptor
- Apoptosis
- B[a]P, benzo[a]pyrene
- CM-H2DCFDA or H2DCFDA, 5-(and 6-)chloromethyl-2,7-dichlorodihydrofluorescein diacetate
- CYP, cytochrome P450
- Chk, checkpoint kinases
- DDR, DNA damage response
- DHE, dihydroethidium
- DMSO, dimethyl sulfoxide
- DNA damage
- ER, endoplasmic reticulum
- Hoechst 33258, 2(2-(4-hydroxyphenyl)-6-benzimidazole-6-(1-methyl-4-piperazyl)benzimidazole hydrochloride)
- Hoechst 33342, 2′-(4-ethoxyphenyl)-2′,5′-bis-1H-benzimidazole hydrochloride)
- NR, nitro-reductasesnitro-PAHnitro substituted-polycyclic aromatic hydrocarbon
- Nitro-PAHs
- PAH, polycyclic aromatic hydrocarbon
- PARP, poly(ADP-ribose) polymerase
- PFT, pifithrin
- PI, propidium iodide
- PM, particular matter
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- SSB, single strand breaks
- UPR, unfolded protein response
- fpg, formamidopyrimidine-DNA glycosylase
- zVAD-FMK, benzyolcarbonayl-Val-Ala-Asp-fluoromethyl ketone
- γH2AX, phosphorylated H2AX
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Affiliation(s)
- J A Holme
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - H E Nyvold
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - V Tat
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - V M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, United Kingdom
| | - A Bhargava
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - K B Gutzkow
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - A Solhaug
- Norwegian Veterinary Institute, Oslo, Norway
| | - M Låg
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - R Becher
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - P E Schwarze
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - K Ask
- Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - L Ekeren
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
| | - J Øvrevik
- Division of Environmental Medicine, Norwegian Institute of Public Health, N-0403 Oslo, Norway
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15
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Hu K, Li W, Gao J, Liu Q, Wang H, Wang Y, Sang J. Role of Ppt1 in multiple stress responses in Candida albicans. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11434-014-0552-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Zhou BH, Wang HW, Zhao ZS, Liu M, Yan WC, Zhao J, Zhang Z, Xue FQ. A novel serine/threonine protein phosphatase type 5 from second-generation merozoite of Eimeria tenella is associated with diclazuril-induced apoptosis. Parasitol Res 2013; 112:1771-80. [PMID: 23417098 DOI: 10.1007/s00436-013-3336-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/31/2013] [Indexed: 11/25/2022]
Abstract
Screening the anticoccidial drug targets is very important for developing novel drugs and revealing the molecular basis of drug resistance in coccidia. Due to high effectivity and safety, diclazuril was used widely in the poultry industry. To assess the roles of the serine/threonine protein phosphatase type 5 of second-generation merozoites in Eimeria tenella (EtPP5) in the anticoccidial activity of diclazuril against chicken coccidiosis, EtPP5 was cloned using reverse transcriptase polymerase chain reaction and rapid amplification of cDNA ends. Ultrastructural changes in second-generation merozoites and mRNA expression level of EtPP5 were monitored by transmission electron microscopy (TEM) and quantitative real-time PCR, respectively. The results showed that the full length of the cloned EtPP5 cDNA (2,495 bp) encompassed a 1,647-bp open reading frame encoding a polypeptide of 548 residues with an estimated molecular mass of 60.82 kDa and a theoretical isoelectric point of 5.89. Molecular analysis of EtPP5 reveals the presence of a C-terminal phosphatase domain and an extended N-terminal tetratricopeptide repeat motif, a typical feature of protein phosphatases. The cDNA sequence has been submitted to the GenBank database with accession number JX987508. EtPP5 shared 89% homology with the published sequence of a PP5 ortholog of Toxoplasma gondii at the amino acid level (GenBank XP_002364442.1). TEM observed that diclazuril induced ultrastructural changes in second-generation merozoites. Quantitative real-time PCR analysis showed that compared with the control group, the level of EtPP5 mRNA expression was significantly downregulated by 51.4% by diclazuril treatment. The high similarity of EtPP5 to previously described PP5 of other organisms, as well as its downregulated expression and connection with apoptosis in the second-generation merozoites induced by diclazuril, suggests that it could act an important role in understanding the signaling mechanism underlining the diclazuril-induced merozoites apoptosis.
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Affiliation(s)
- Bian-hua Zhou
- College of Animal Science and Technology, Henan University of Science and Technology, 70 Tianjin Road, Jianxi, Luoyang, Hehan, 471003, China
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17
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Calderwood SK. Molecular cochaperones: tumor growth and cancer treatment. SCIENTIFICA 2013; 2013:217513. [PMID: 24278769 PMCID: PMC3820307 DOI: 10.1155/2013/217513] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/01/2013] [Indexed: 05/12/2023]
Abstract
Molecular chaperones play important roles in all cellular organisms by maintaining the proteome in an optimally folded state. They appear to be at a premium in cancer cells whose evolution along the malignant pathways requires the fostering of cohorts of mutant proteins that are employed to overcome tumor suppressive regulation. To function at significant rates in cells, HSPs interact with cochaperones, proteins that assist in catalyzing individual steps in molecular chaperoning as well as in posttranslational modification and intracellular localization. We review current knowledge regarding the roles of chaperones such as heat shock protein 90 (Hsp90) and Hsp70 and their cochaperones in cancer. Cochaperones are potential targets for cancer therapy in themselves and can be used to assess the likely prognosis of individual malignancies. Hsp70 cochaperones Bag1, Bag3, and Hop play significant roles in the etiology of some cancers as do Hsp90 cochaperones Aha1, p23, Cdc37, and FKBP1. Others such as the J domain protein family, HspBP1, TTC4, and FKBPL appear to be associated with more benign tumor phenotypes. The key importance of cochaperones for many pathways of protein folding in cancer suggests high promise for the future development of novel pharmaceutical agents.
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Affiliation(s)
- Stuart K. Calderwood
- Division of Molecular and Cellular Biology, Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, 99 Brookline Avenue, Boston, MA 02215, USA
- *Stuart K. Calderwood:
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18
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Bruce DL, Macartney T, Yong W, Shou W, Sapkota GP. Protein phosphatase 5 modulates SMAD3 function in the transforming growth factor-β pathway. Cell Signal 2012; 24:1999-2006. [PMID: 22781750 DOI: 10.1016/j.cellsig.2012.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 07/03/2012] [Indexed: 02/02/2023]
Abstract
Protein phosphatases play a key role in balancing the cellular responses to the transforming growth factor-β (TGFβ) signals. Several protein phosphatases have been attributed roles in the regulation of the TGFβ pathway. Among these, PPM1A is the only phosphatase reported to dephosphorylate SMAD2/3 in the nucleus. However we observed PPM1A exclusively in the cytoplasmic fractions independently of TGFβ treatment in all cells tested. These observations imply that a bona fide nuclear SMAD2/3 phosphatase remains elusive. In this study, we report a role for protein phosphatase 5 (PP5) in the TGFβ pathway. We identified PP5 as an interactor of SMAD2/3. Interestingly, in mouse embryonic fibroblast cells derived from PP5-null mice, TGFβ-induced transcriptional responses were significantly enhanced. Rather surprisingly, this enhancement is due to the increased levels of SMAD3 protein observed in PP5-null MEFs compared to the wild type. No differences in the levels of SMAD3 transcripts were observed between the wild-type and PP5-null MEFs. While PP5 is capable of dephosphorylating SMAD3-tail in overexpression assays, we demonstrate that its activity is essential in controlling SMAD3 protein levels in MEFs. We propose that PP5 regulates the TGFβ pathway in MEFs by regulating the expression of SMAD3 protein levels.
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Affiliation(s)
- David L Bruce
- MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, UK
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19
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Furusawa Y, Iizumi T, Fujiwara Y, Zhao QL, Tabuchi Y, Nomura T, Kondo T. Inhibition of checkpoint kinase 1 abrogates G2/M checkpoint activation and promotes apoptosis under heat stress. Apoptosis 2012; 17:102-12. [PMID: 22080164 DOI: 10.1007/s10495-011-0660-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Hyperthermia induced by heat stress (HS) inhibits the proliferation of cancer cells and induces their apoptosis. However, the mechanism underlying HS-induced apoptosis remains elusive. Here, we demonstrated a novel evidence that checkpoint kinase 1 (Chk1) plays crucial roles in the apoptosis and regulation of cell cycle progression in cells under HS. In human leukemia Jurkat cells, interestingly, the ataxia telangiectasia and Rad-3 related (ATR)-Chk1 pathway was preferentially activated rather than the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 (Chk2) pathway under HS. The selective inhibitors of ATR or Chk1 abrogated HS-induced apoptosis in human leukemia Jurkat cells whereas the inhibition of ATM or Chk2 caused only marginal effects. Inhibition of ATR and Chk1 also abrogated G2/M checkpoint activation by HS in Jurkat cells. The effects of small interfering RNA targeting Chk1 were similar to those of the selective inhibitor of Chk1. In addition, the efficiencies of Chk1 inhibition on G2/M checkpoint abrogation and apoptosis induction were confirmed in the adherent cancer cell lines HeLa, HSC3, and PC3, suggesting that the targeting of Chk1 can be effective in solid tumors cells. In conclusion, these findings indicate a novel molecular basis of G2/M checkpoint activation and apoptosis in cells exposed to HS.
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Affiliation(s)
- Yukihiro Furusawa
- Department of Radiological Sciences, Life Science Research Center, Graduate School of Medicine Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
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20
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21
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Lee DH, Chowdhury D. What goes on must come off: phosphatases gate-crash the DNA damage response. Trends Biochem Sci 2011; 36:569-77. [PMID: 21930385 DOI: 10.1016/j.tibs.2011.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/24/2022]
Abstract
DNA-damage-induced phospho-signaling has been studied for decades, with a focus mainly on initiation of the signaling cascade, and the kinases activated by DNA lesions. It is widely accepted that the balance of phosphorylation needs to be restored and/or maintained by phosphatases, yet there have only been sporadic efforts to investigate the impact of phosphatases on DNA repair. Recent advances in phosphoproteomic strategies and implementation of large genetic screens indicate that these enzymes play pivotal roles in these signaling networks. Dephosphorylation of repair proteins is crucial for efficient DNA repair, and the recommencement of cell division post-repair. Here, we focus on serine/threonine phosphatases implicated in dephosphorylation of DNA repair factors, summarizing recent findings and speculating on untested roles of phosphatases in the DNA damage response.
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Affiliation(s)
- Dong-Hyun Lee
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
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22
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Amable L, Grankvist N, Largen JW, Ortsäter H, Sjöholm Å, Honkanen RE. Disruption of serine/threonine protein phosphatase 5 (PP5:PPP5c) in mice reveals a novel role for PP5 in the regulation of ultraviolet light-induced phosphorylation of serine/threonine protein kinase Chk1 (CHEK1). J Biol Chem 2011; 286:40413-22. [PMID: 21921034 DOI: 10.1074/jbc.m111.244053] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PP5 is a ubiquitously expressed Ser/Thr protein phosphatase. High levels of PP5 have been observed in human cancers, and constitutive PP5 overexpression aids tumor progression in mouse models of tumor development. However, PP5 is highly conserved among species, and the roles of PP5 in normal tissues are not clear. Here, to help evaluate the biological actions of PP5, a Cre/loxP-conditional mouse line was generated. In marked contrast to the early embryonic lethality associated with the genetic disruption of other PPP family phosphatases (e.g. PP2A and PP4), intercrosses with mouse lines that ubiquitously express Cre recombinase starting early in development (e.g. MeuCre40 and ACTB-Cre) produced viable and fertile PP5-deficient mice. Phenotypic differences caused by the total disruption of PP5 were minor, suggesting that small molecule inhibitors of PP5 will not have widespread systemic toxicity. Examination of roles for PP5 in fibroblasts generated from PP5-deficient embryos (PP5(-/-) mouse embryonic fibroblasts) confirmed some known roles and identified new actions for PP5. PP5(-/-) mouse embryonic fibroblasts demonstrated increased sensitivity to UV light, hydroxyurea, and camptothecin, which are known activators of ATR (ataxia-telangiectasia and Rad3-related) kinase. Further study revealed a previously unrecognized role for PP5 downstream of ATR activation in a UV light-induced response. The genetic disruption of PP5 is associated with enhanced and prolonged phosphorylation of a single serine (Ser-345) on Chk1, increased phosphorylation of the p53 tumor suppressor protein (p53) at serine 18, and increased p53 protein levels. A comparable role for PP5 in the regulation of Chk1 phosphorylation was also observed in human cells.
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Affiliation(s)
- Lauren Amable
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, Alabama 36688, USA
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23
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Importance of PIKKs in NF-κB activation by genotoxic stress. Biochem Pharmacol 2011; 82:1371-83. [PMID: 21872579 DOI: 10.1016/j.bcp.2011.07.105] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 07/26/2011] [Accepted: 07/29/2011] [Indexed: 01/11/2023]
Abstract
Alteration of the genome integrity leads to the activation of a vast network of cellular responses named "DNA damage response". Three kinases from the phosphoinositide 3-kinase-like protein kinase family regulate this network; ATM and DNA-PK both activated by DNA double-strand breaks and ATR activated by replication blocks. "DNA damage response" pathway coordinates cell cycle arrest, DNA repair, and the activation of transcription factors such as p53 and NF-κB. It controls senescence/apoptosis/survival of the damaged cells. Cell death or survival result from a tightly regulated balance between antagonist pro- and anti-apoptotic signals. NF-κB is a key transcription factor involved in immunity, inflammation and cell transformation. When activated by DNA double-strand breaks, NF-κB has most often a pro-survival effect and thereof interferes with chemotherapy treatments that often rely on DNA damage to induce tumor cell death (i.e. topoisomerase inhibitors and ionizing radiation). NF-κB is thus an important pharmaceutical target. Agents leading to replication stress induce a pro-apoptotic NF-κB. The molecular mechanisms initiated by DNA lesions leading to NF-κB nuclear translocation have been extensively studied these last years. In this review, we will focus on ATM, ATR and DNA-PK functions both in the IKKα/IKKβ/NEMO-dependent or -independent signaling pathways and on the regulation they can exercise at the promoter level of NF-κB regulated genes.
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24
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Park JH, Lee SY, Kim WY, Jung YJ, Chae HB, Jung HS, Kang CH, Shin MR, Kim SY, Su'udi M, Yun DJ, Lee KO, Kim MG, Lee SY. Heat-induced chaperone activity of serine/threonine protein phosphatase 5 enhances thermotolerance in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2011; 191:692-705. [PMID: 21564098 DOI: 10.1111/j.1469-8137.2011.03734.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
• This study reports that Arabidopsis thaliana protein serine/threonine phosphatase 5 (AtPP5) plays a pivotal role in heat stress resistance. A high-molecular-weight (HMW) form of AtPP5 was isolated from heat-treated A. thaliana suspension cells. AtPP5 performs multiple functions, acting as a protein phosphatase, foldase chaperone, and holdase chaperone. The enzymatic activities of this versatile protein are closely associated with its oligomeric status, ranging from low oligomeric protein species to HMW complexes. • The phosphatase and foldase chaperone functions of AtPP5 are associated primarily with the low-molecular-weight (LMW) form, whereas the HMW form exhibits holdase chaperone activity. Transgenic over-expression of AtPP5 conferred enhanced heat shock resistance to wild-type A. thaliana and a T-DNA insertion knock-out mutant was defective in acquired thermotolerance. A recombinant phosphatase mutant (H290N) showed markedly increased holdase chaperone activity. • In addition, enhanced thermotolerance was observed in transgenic plants over-expressing H290N, which suggests that the holdase chaperone activity of AtPP5 is primarily responsible for AtPP5-mediated thermotolerance. • Collectively, the results from this study provide the first evidence that AtPP5 performs multiple enzymatic activities that are mediated by conformational changes induced by heat-shock stress.
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Affiliation(s)
- Jin Ho Park
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Sun Yong Lee
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Woe Yeon Kim
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Young Jun Jung
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Ho Byoung Chae
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Hyun Suk Jung
- Division of Electron Microscopic Research, Korea Basic Science Institute, 52 Eoeun-dong, Daejeon 305-333, Korea
| | - Chang Ho Kang
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Mi Rim Shin
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Sun Young Kim
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Mukhamad Su'udi
- National Academy of Agricultural Science, RDA, Suwon 441-856, Korea
| | - Dae Jin Yun
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Kyun Oh Lee
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
| | - Min Gab Kim
- National Academy of Agricultural Science, RDA, Suwon 441-856, Korea
| | - Sang Yeol Lee
- Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, Korea
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