1
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Singh A, Busacca S, Gaba A, Sheaff M, Poile C, Nakas A, Dzialo J, Bzura A, Dawson AG, Fennell DA, Fry AM. BAP1 loss induces mitotic defects in mesothelioma cells through BRCA1-dependent and independent mechanisms. Oncogene 2023; 42:572-585. [PMID: 36550359 PMCID: PMC9937923 DOI: 10.1038/s41388-022-02577-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022]
Abstract
The tumour suppressor BRCA1-associated protein 1 (BAP1) is the most frequently mutated cancer gene in mesothelioma. Here we report novel functions for BAP1 in mitotic progression highlighting the relationship between BAP1 and control of genome stability in mesothelioma cells with therapeutic implications. Depletion of BAP1 protein induced proteasome-mediated degradation of BRCA1 in mesothelioma cells while loss of BAP1 correlated with BRCA1 loss in mesothelioma patient tumour samples. BAP1 loss also led to mitotic defects that phenocopied the loss of BRCA1 including spindle assembly checkpoint failure, centrosome amplification and chromosome segregation errors. However, loss of BAP1 also led to additional mitotic changes that were not observed upon BRCA1 loss, including an increase in spindle length and enhanced growth of astral microtubules. Intriguingly, these consequences could be explained by loss of expression of the KIF18A and KIF18B kinesin motors that occurred upon depletion of BAP1 but not BRCA1, as spindle and astral microtubule defects were rescued by re-expression of KIF18A and KIF18B, respectively. We therefore propose that BAP1 inactivation causes mitotic defects through BRCA1-dependent and independent mechanisms revealing novel routes by which mesothelioma cells lacking BAP1 may acquire genome instability and exhibit altered responses to microtubule-targeted agents.
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Affiliation(s)
- Anita Singh
- grid.9918.90000 0004 1936 8411Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, Leicester, LE1 9HN UK ,grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Sara Busacca
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Aarti Gaba
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Michael Sheaff
- Department of Histopathology, Barts Health NHS Trust, Queen Mary University of London, The Royal London Hospital, London, E1 2ES UK
| | - Charlotte Poile
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Apostolos Nakas
- grid.412925.90000 0004 0400 6581University Hospitals of Leicester NHS Trust, Glenfield Hospital, Leicester, LE3 9QP UK
| | - Joanna Dzialo
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Aleksandra Bzura
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK
| | - Alan G. Dawson
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK ,grid.412925.90000 0004 0400 6581University Hospitals of Leicester NHS Trust, Glenfield Hospital, Leicester, LE3 9QP UK
| | - Dean A. Fennell
- grid.9918.90000 0004 1936 8411Leicester Cancer Research Centre, Department of Genetics and Genome Biology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX UK ,grid.412925.90000 0004 0400 6581University Hospitals of Leicester NHS Trust, Glenfield Hospital, Leicester, LE3 9QP UK
| | - Andrew M. Fry
- grid.9918.90000 0004 1936 8411Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, Leicester, LE1 9HN UK
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2
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Antonova A, Hummel B, Khavaran A, Redhaber DM, Aprile-Garcia F, Rawat P, Gundel K, Schneck M, Hansen EC, Mitschke J, Mittler G, Miething C, Sawarkar R. Heat-Shock Protein 90 Controls the Expression of Cell-Cycle Genes by Stabilizing Metazoan-Specific Host-Cell Factor HCFC1. Cell Rep 2020; 29:1645-1659.e9. [PMID: 31693902 DOI: 10.1016/j.celrep.2019.09.084] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 08/06/2019] [Accepted: 09/27/2019] [Indexed: 12/18/2022] Open
Abstract
Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding. Their function in the cytosol has been well studied. Notably, chaperones are also present in the nucleus, a compartment where proteins enter after completing de novo folding in the cytosol, and this raises an important question about chaperone function in the nucleus. We performed a systematic analysis of the nuclear pool of heat-shock protein 90. Three orthogonal and independent analyses led us to the core functional interactome of HSP90. Computational and biochemical analyses identify host cell factor C1 (HCFC1) as a transcriptional regulator that depends on HSP90 for its stability. HSP90 was required to maintain the expression of HCFC1-targeted cell-cycle genes. The regulatory nexus between HSP90 and the HCFC1 module identified in this study sheds light on the relevance of chaperones in the transcription of cell-cycle genes. Our study also suggests a therapeutic avenue of combining chaperone and transcription inhibitors for cancer treatment.
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Affiliation(s)
- Aneliya Antonova
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Barbara Hummel
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Ashkan Khavaran
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Desiree M Redhaber
- German Consortium for Translational Cancer Research (DKTK), Partner Site Freiburg and German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Prashant Rawat
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Kathrin Gundel
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Megan Schneck
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Erik C Hansen
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Jan Mitschke
- Department of Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany
| | - Gerhard Mittler
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Cornelius Miething
- German Consortium for Translational Cancer Research (DKTK), Partner Site Freiburg and German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Ritwick Sawarkar
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany; MRC Toxicology Unit, University of Cambridge, Cambridge, UK.
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3
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Quintana AM, Yu HC, Brebner A, Pupavac M, Geiger EA, Watson A, Castro VL, Cheung W, Chen SH, Watkins D, Pastinen T, Skovby F, Appel B, Rosenblatt DS, Shaikh TH. Mutations in THAP11 cause an inborn error of cobalamin metabolism and developmental abnormalities. Hum Mol Genet 2018; 26:2838-2849. [PMID: 28449119 DOI: 10.1093/hmg/ddx157] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/20/2017] [Indexed: 11/14/2022] Open
Abstract
CblX (MIM309541) is an X-linked recessive disorder characterized by defects in cobalamin (vitamin B12) metabolism and other developmental defects. Mutations in HCFC1, a transcriptional co-regulator which interacts with multiple transcription factors, have been associated with cblX. HCFC1 regulates cobalamin metabolism via the regulation of MMACHC expression through its interaction with THAP11, a THAP domain-containing transcription factor. The HCFC1/THAP11 complex potentially regulates genes involved in diverse cellular functions including cell cycle, proliferation, and transcription. Thus, it is likely that mutation of THAP11 also results in biochemical and other phenotypes similar to those observed in patients with cblX. We report a patient who presented with clinical and biochemical phenotypic features that overlap cblX, but who does not have any mutations in either MMACHC or HCFC1. We sequenced THAP11 by Sanger sequencing and discovered a potentially pathogenic, homozygous variant, c.240C > G (p.Phe80Leu). Functional analysis in the developing zebrafish embryo demonstrated that both THAP11 and HCFC1 regulate the proliferation and differentiation of neural precursors, suggesting important roles in normal brain development. The loss of THAP11 in zebrafish embryos results in craniofacial abnormalities including the complete loss of Meckel's cartilage, the ceratohyal, and all of the ceratobranchial cartilages. These data are consistent with our previous work that demonstrated a role for HCFC1 in vertebrate craniofacial development. High throughput RNA-sequencing analysis reveals several overlapping gene targets of HCFC1 and THAP11. Thus, both HCFC1 and THAP11 play important roles in the regulation of cobalamin metabolism as well as other pathways involved in early vertebrate development.
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Affiliation(s)
- Anita M Quintana
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968, USA
| | - Hung-Chun Yu
- Section of Genetics, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Alison Brebner
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Mihaela Pupavac
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Elizabeth A Geiger
- Section of Genetics, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Abigail Watson
- Section of Genetics, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Victoria L Castro
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968, USA
| | - Warren Cheung
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Shu-Huang Chen
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - David Watkins
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Tomi Pastinen
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Flemming Skovby
- Department of Clinical Genetics, Rigshospitalet, and Institute of Clinical Medicine, University of Copenhagen, Copenhagen, 2100 Denmark
| | - Bruce Appel
- Section of Developmental Biology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - David S Rosenblatt
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada
| | - Tamim H Shaikh
- Section of Genetics, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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4
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Rebelo S, Santos M, Martins F, da Cruz e Silva EF, da Cruz e Silva OA. Protein phosphatase 1 is a key player in nuclear events. Cell Signal 2015; 27:2589-98. [DOI: 10.1016/j.cellsig.2015.08.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/31/2015] [Accepted: 08/10/2015] [Indexed: 12/17/2022]
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5
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Korrodi-Gregório L, Esteves SLC, Fardilha M. Protein phosphatase 1 catalytic isoforms: specificity toward interacting proteins. Transl Res 2014; 164:366-91. [PMID: 25090308 DOI: 10.1016/j.trsl.2014.07.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/26/2014] [Accepted: 07/01/2014] [Indexed: 01/21/2023]
Abstract
The coordinated and reciprocal action of serine-threonine protein kinases and protein phosphatases produces transitory phosphorylation, a fundamental regulatory mechanism for many biological processes. Phosphoprotein phosphatase 1 (PPP1), a major serine-threonine phosphatase, in particular, is ubiquitously distributed and regulates a broad range of cellular functions, including glycogen metabolism, cell cycle progression, and muscle relaxation. PPP1 has evolved effective catalytic machinery but in vitro lacks substrate specificity. In vivo, its specificity is achieved not only by the existence of different PPP1 catalytic isoforms, but also by binding of the catalytic moiety to a large number of regulatory or targeting subunits. Here, we will address exhaustively the existence of diverse PPP1 catalytic isoforms and the relevance of their specific partners and consequent functions.
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Affiliation(s)
- Luís Korrodi-Gregório
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
| | - Sara L C Esteves
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
| | - Margarida Fardilha
- Laboratório de Transdução de Sinais, Departamento de Biologia, Secção Autónoma de Ciências de Saúde, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal.
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6
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Host cell factor-1 recruitment to E2F-bound and cell-cycle-control genes is mediated by THAP11 and ZNF143. Cell Rep 2014; 9:967-82. [PMID: 25437553 DOI: 10.1016/j.celrep.2014.09.051] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 09/03/2014] [Accepted: 09/28/2014] [Indexed: 11/21/2022] Open
Abstract
Host cell factor-1 (HCF-1) is a metazoan transcriptional coregulator essential for cell-cycle progression and cell proliferation. Current models suggest a mechanism whereby HCF-1 functions as a direct coregulator of E2F proteins, facilitating the expression of genes necessary for cell proliferation. In this report, we show that HCF-1 recruitment to numerous E2F-bound promoters is mediated by the concerted action of zinc finger transcription factors THAP11 and ZNF143, rather than E2F proteins directly. THAP11, ZNF143, and HCF-1 form a mutually dependent complex on chromatin, which is independent of E2F occupancy. Disruption of the THAP11/ZNF143/HCF-1 complex results in altered expression of cell-cycle control genes and leads to reduced cell proliferation, cell-cycle progression, and cell viability. These data establish a model in which a THAP11/ZNF143/HCF-1 complex is a critical component of the transcriptional regulatory network governing cell proliferation.
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7
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A transcriptional regulatory role of the THAP11-HCF-1 complex in colon cancer cell function. Mol Cell Biol 2012; 32:1654-70. [PMID: 22371484 DOI: 10.1128/mcb.06033-11] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The recently identified Thanatos-associated protein (THAP) domain is an atypical zinc finger motif with sequence-specific DNA-binding activity. Emerging data suggest that THAP proteins may function in chromatin-dependent processes, including transcriptional regulation, but the roles of most THAP proteins in normal and aberrant cellular processes remain largely unknown. In this work, we identify THAP11 as a transcriptional regulator differentially expressed in human colon cancer. Immunohistochemical analysis of human colon cancers revealed increased THAP11 expression in both primary tumors and metastases. Knockdown of THAP11 in SW620 colon cancer cells resulted in a significant decrease in cell proliferation, and profiling of gene expression in these cells identified a novel gene set composed of 80 differentially expressed genes, 70% of which were derepressed by THAP11 knockdown. THAP11 was found to associate physically with the transcriptional coregulator HCF-1 (host cell factor 1) and recruit HCF-1 to target promoters. Importantly, THAP11-mediated gene regulation and its chromatin association require HCF-1, while HCF-1 recruitment at these genes requires THAP11. Collectively, these data provide the first characterization of THAP11-dependent gene expression in human colon cancer cells and suggest that the THAP11-HCF-1 complex may be an important transcriptional and cell growth regulator in human colon cancer.
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8
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Eletr ZM, Wilkinson KD. An emerging model for BAP1's role in regulating cell cycle progression. Cell Biochem Biophys 2011; 60:3-11. [PMID: 21484256 DOI: 10.1007/s12013-011-9184-6] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BRCA1-associated protein-1 (BAP1) is a 729 residue, nuclear-localized deubiquitinating enzyme (DUB) that displays tumor suppressor properties in the BAP1-null NCI-H226 lung carcinoma cell line. Studies that have altered BAP1 cellular levels or enzymatic activity have reported defects in cell cycle progression, notably at the G1/S transition. Recently BAP1 was shown to associate with the transcriptional regulator host cell factor 1 (HCF-1). The BAP1/HCF-1 interaction is mediated by the HCF-1 Kelch domain and an HCF-1 binding motif (HBM) within BAP1. HCF-1 is modified with ubiquitin in vivo, and ectopic studies suggest BAP1 deubiquitinates HCF-1. HCF-1 is a chromatin-associated protein thought to both activate and repress transcription by linking appropriate histone-modifying enzymes to a subset of transcription factors. One known role of HCF-1 is to promote cell cycle progression at the G1/S boundary by recruiting H3K4 histone methyltransferases to the E2F1 transcription factor so that genes required for S-phase can be transcribed. Given the robust associations between BAP1/HCF-1 and HCF-1/E2Fs, it is reasonable to speculate that BAP1 influences cell proliferation at G1/S by co-regulating transcription from HCF-1/E2F-governed promoters.
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Affiliation(s)
- Ziad M Eletr
- Department of Biochemistry, Emory University, Atlanta, GA 30322, USA
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9
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Cruz JLG, Sola I, Becares M, Alberca B, Plana J, Enjuanes L, Zuñiga S. Coronavirus gene 7 counteracts host defenses and modulates virus virulence. PLoS Pathog 2011; 7:e1002090. [PMID: 21695242 PMCID: PMC3111541 DOI: 10.1371/journal.ppat.1002090] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 04/12/2011] [Indexed: 12/14/2022] Open
Abstract
Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus.
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Affiliation(s)
- Jazmina L. G. Cruz
- Centro Nacional de Biotecnología, CNB, CSIC, Department of Molecular and Cell Biology, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Isabel Sola
- Centro Nacional de Biotecnología, CNB, CSIC, Department of Molecular and Cell Biology, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Martina Becares
- Centro Nacional de Biotecnología, CNB, CSIC, Department of Molecular and Cell Biology, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | | | | | - Luis Enjuanes
- Centro Nacional de Biotecnología, CNB, CSIC, Department of Molecular and Cell Biology, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
- * E-mail:
| | - Sonia Zuñiga
- Centro Nacional de Biotecnología, CNB, CSIC, Department of Molecular and Cell Biology, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
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10
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Abstract
Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus.
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11
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Lee S, Horn V, Julien E, Liu Y, Wysocka J, Bowerman B, Hengartner MO, Herr W. Epigenetic regulation of histone H3 serine 10 phosphorylation status by HCF-1 proteins in C. elegans and mammalian cells. PLoS One 2007; 2:e1213. [PMID: 18043729 PMCID: PMC2082077 DOI: 10.1371/journal.pone.0001213] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Accepted: 10/30/2007] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The human herpes simplex virus (HSV) host cell factor HCF-1 is a transcriptional coregulator that associates with both histone methyl- and acetyltransferases, and a histone deacetylase and regulates cell proliferation and division. In HSV-infected cells, HCF-1 associates with the viral protein VP16 to promote formation of a multiprotein-DNA transcriptional activator complex. The ability of HCF proteins to stabilize this VP16-induced complex has been conserved in diverse animal species including Drosophila melanogaster and Caenorhabditis elegans suggesting that VP16 targets a conserved cellular function of HCF-1. METHODOLOGY/PRINCIPAL FINDINGS To investigate the role of HCF proteins in animal development, we have characterized the effects of loss of the HCF-1 homolog in C. elegans, called Ce HCF-1. Two large hcf-1 deletion mutants (pk924 and ok559) are viable but display reduced fertility. Loss of Ce HCF-1 protein at reduced temperatures (e.g., 12 degrees C), however, leads to a high incidence of embryonic lethality and early embryonic mitotic and cytokinetic defects reminiscent of mammalian cell-division defects upon loss of HCF-1 function. Even when viable, however, at normal temperature, mutant embryos display reduced levels of phospho-histone H3 serine 10 (H3S10P), a modification implicated in both transcriptional and mitotic regulation. Mammalian cells with defective HCF-1 also display defects in mitotic H3S10P status. CONCLUSIONS/SIGNIFICANCE These results suggest that HCF-1 proteins possess conserved roles in the regulation of cell division and mitotic histone phosphorylation.
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Affiliation(s)
- Soyoung Lee
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
- Program in Molecular and Cellular Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Virginie Horn
- Center for Integrative Genomics, University of Lausanne, Génopode, Lausanne, Switzerland
| | - Eric Julien
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Yi Liu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Joanna Wysocka
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Michael O. Hengartner
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Winship Herr
- Center for Integrative Genomics, University of Lausanne, Génopode, Lausanne, Switzerland
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
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Browne G, Fardilha M, Oxenham S, Wu W, Helps N, da Cruz E Silva O, Cohen P, Cruz E Silva E. SARP, a new alternatively spliced protein phosphatase 1 and DNA interacting protein. Biochem J 2007; 402:187-96. [PMID: 17123353 PMCID: PMC1783986 DOI: 10.1042/bj20060600] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PP1 (protein phosphatase 1) is a ubiquitously expressed serine/threonine-specific protein phosphatase whose activity towards different substrates appears to be mediated via binding to specific proteins that play critical regulatory and targeting roles. In the present paper we report the cloning and characterization of a new protein, termed SARP (several ankyrin repeat protein), which is shown to interact with all isoforms of PP1 by a variety of techniques. A region encompassing a consensus PP1-binding motif in SARP (K354VHF357) modulates endogenous SARP-PP1 activity in mammalian cells. This SARP-PP1 interaction motif lies partially within the first ankyrin repeat in contrast with other proteins [53BP2 (p53 binding protein 2), MYPT1/M(110)/MBS (myosin binding protein of PP1) and TIMAP (transforming growth factor beta inhibited, membrane-associated protein)], where a PP1-binding motif precedes the ankyrin repeats. Alternative mRNA splicing produces several isoforms of SARP from a single human gene at locus 11q14. SARP1 and/or SARP2 (92-95 kDa) are ubiquitously expressed in all tissues with high levels in testis and sperm, where they are shown to interact with both PP1gamma1 and PP1gamma2. SARP3 (65 kDa) is most abundant in brain where SARP isoforms interact with both PP1alpha and PP1gamma1. SARP is highly abundant in the nucleus of mammalian cells, consistent with the putative nuclear localization signal at the N-terminus. The presence of a leucine zipper near the C-terminus of SARP1 and SARP2, and the binding of mammalian DNA to SARP2, suggests that SARP1 and SARP2 may be transcription factors or DNA-associated proteins that modulate gene expression.
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Affiliation(s)
- Gareth J. Browne
- *Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Margarida Fardilha
- †Laboratório de Transdução de Sinais, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Senga K. Oxenham
- *Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Wenjuan Wu
- †Laboratório de Transdução de Sinais, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Nicholas R. Helps
- *Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Odete A. B. da Cruz E Silva
- ‡Laboratório de Neurociências, Centro de Biologia Celular, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Patricia T. W. Cohen
- *Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
- To whom correspondence should be addressed (email )
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13
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Knez J, Piluso D, Bilan P, Capone JP. Host Cell Factor-1 and E2F4 Interact Via Multiple Determinants in Each Protein. Mol Cell Biochem 2006; 288:79-90. [PMID: 16633736 DOI: 10.1007/s11010-006-9122-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 01/09/2006] [Indexed: 12/17/2022]
Abstract
Host Cell Factor (HCF-1) is a conserved, essential protein initially identified as a co-regulator for the Herpes Simplex Virus transactivator VP16. HCF-1 is variously involved in regulating transcription, splicing, cell proliferation and cytokinesis; however, its mechanisms of action remain unknown. HCF-1 function is manifested through an increasing assortment of cellular factors that target different regions of the protein. Several HCF-1 partners target the amino-terminal kelch domain of HCF-1 (residues 1-380) via a consensus HCF-binding motif (HBM) comprising the tetrapeptide (D/E)HXY. Searches of sequence databases indicated that this motif is present in E2F1 and E2F4, two members of the E2F family of cell cycle regulators. We show here that E2F4 specifically and directly interacts with HCF-1. Mutational analysis showed E2F4 independently targets the kelch domain and the basic domain (residues 450-902) of HCF-1, both of which are required for normal cell-cycle progression via separate determinants. The HBM-containing domain of E2F4 was necessary for interaction with the kelch domain of HCF-1 but not for interaction with the basic domain. Mutations in the HCF-1 kelch domain known to block cell growth abrogated E2F4 binding to the kelch domain in the absence but not in the presence of the juxtaposed basic region. Functionally, HCF-1 co-activated E2F4/DP-1 in transient transfection assays, while E2F4 blocked HCF-1-dependent rescue of a cell line that harbors a temperature sensitive mutant of HCF-1 that causes growth arrest. Our findings show that HCF-1 and E2F4 interact via multiple determinants and suggest a linkage between E2F4 and HCF-1 cell growth pathways.
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Affiliation(s)
- Jozo Knez
- Department of Biochemistry and Biomedical Sciences, McMaster University Medical Center, McMaster University, 1200 Main St. W., Hamilton, Ontario, L8N 3Z5, Canada
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14
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Chen J, Davé SK, Simmons A. Prevention of genital herpes in a guinea pig model using a glycoprotein D-specific single chain antibody as a microbicide. Virol J 2004; 1:11. [PMID: 15560847 PMCID: PMC535897 DOI: 10.1186/1743-422x-1-11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 11/23/2004] [Indexed: 11/12/2022] Open
Abstract
Background Genital herpes (GH) is a recurrent sexually transmitted infection (STI) that causes significant morbidity and is also the major source of herpes simplex virus (HSV) in cases of neonatal herpes. Vaccination is a current goal which has had limited success so far in preventing GH and microbicides offer an attractive alternative. Treatment of primary disease cannot prevent establishment of latent infections and thus, cannot prevent subsequent recurrent disease. Recently, many of the molecular events leading to entry of HSV into cells have been elucidated, resulting in the description of a number of herpesvirus entry mediators (HVEMs) that interact with HSV glycoprotein D (gD) on the surface of virions. Described here is a strategy for interrupting the spread of HSV based on interfering with these interactions. The hypothesis addressed in the current report was that single chain antibody variable fragments (scFv) that interrupt associations between gD and HVEMs would not only prevent infection in vitro but could also be used as microbicides to interfere with acquisition GH. Results and Conclusions Here we show that a scFv derived from a particular hybridoma, DL11, not only inhibits infection in vitro but also prevents development of GH in a guinea pig model when applied intravaginally in an inert vehicle. Comparison of different anti-gD single chain antibodies supported the hypothesis that the activity of DL11-scFv is based on its ability to disrupt the associations between gD and the two major receptors for HSV, nectin-1 and HveA. Further, the results predict that bacterial expression of active single chain antibodies can be optimized to manufacture inexpensively a useful microbicidal product active against HSV.
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Affiliation(s)
- Jianmin Chen
- University of Texas Medical Branch, Galveston, Texas, USA
| | - Sanat K Davé
- University of Texas Medical Branch, Galveston, Texas, USA
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15
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Khurana B, Kristie TM. A Protein Sequestering System Reveals Control of Cellular Programs by the Transcriptional Coactivator HCF-1. J Biol Chem 2004; 279:33673-83. [PMID: 15190068 DOI: 10.1074/jbc.m401255200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian transcriptional coactivator HCF-1 is a critical component of the multiprotein herpes simplex virus immediate early gene enhancer core complex. The protein has also been implicated in basic cellular processes such as cell-cycle progression, transcriptional coactivation, and mRNA processing. Functions have been attributed to HCF-1 primarily from analyses of protein-protein interactions and from the cell-cycle-arrested phenotype of an HCF-1 temperature-sensitive mutant. However, neither the mechanisms involved nor specific cellular transcriptional targets have been identified. As the protein is essential for cell viability and proliferation, a genetic system was developed to specifically sequester the nuclear factor in the cell cytoplasm in a regulated manner. This approach exhibits no significant cell toxicity yet clearly demonstrates the requirement of available nuclear HCF-1 for herpes simplex virus immediate early gene expression during productive infection. Additionally, cellular transcriptional events were identified that contribute to understanding the functions ascribed to the protein and implicate the protein in events that impact the regulation of critical cellular processes.
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Affiliation(s)
- Bharat Khurana
- Laboratory of Viral Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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16
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Moorefield KS, Fry SJ, Horowitz JM. Sp2 DNA Binding Activity and trans-Activation Are Negatively Regulated in Mammalian Cells. J Biol Chem 2004; 279:13911-24. [PMID: 14726517 DOI: 10.1074/jbc.m313589200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have indicated that Sp2 binds poorly to GC-rich sequences bound by Sp1 and Sp3, and further functional analyses of Sp2 have been limited. To study Sp2-mediated transcription, we employed a PCR-based protocol to determine the Sp2 consensus DNA-binding sequence (5'-GGGCGGGAC-3') and performed kinetic experiments to show that Sp2 binds this consensus sequence with high affinity (225 pm) in vitro. To determine the functional consequence of Sp2 interaction with this sequence in vivo, we transformed well characterized Sp-binding sites within the dihydrofolate reductase (DHFR) promoter to consensus Sp2-binding sites. Incorporation of Sp2-binding sites within the DHFR promoter increased Sp2-mediated trans-activation in transient co-transfection experiments but also revealed Sp2 to be a relatively weak trans-activator with little or no capacity for additive or synergistic trans-activation. Using chimeric molecules prepared with portions of Sp1 and Sp2 and the human prostate-specific antigen promoter, we show that Sp2 DNA binding activity and trans-activation are negatively regulated in mammalian cells. Taken together, our data indicate that Sp2 is functionally distinct relative to other Sp family members and suggest that Sp2 may play a unique role in cell physiology.
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Affiliation(s)
- K Scott Moorefield
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA
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17
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Ceulemans H, Bollen M. Functional diversity of protein phosphatase-1, a cellular economizer and reset button. Physiol Rev 2004; 84:1-39. [PMID: 14715909 DOI: 10.1152/physrev.00013.2003] [Citation(s) in RCA: 490] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The protein serine/threonine phosphatase protein phosphatase-1 (PP1) is a ubiquitous eukaryotic enzyme that regulates a variety of cellular processes through the dephosphorylation of dozens of substrates. This multifunctionality of PP1 relies on its association with a host of function-specific targetting and substrate-specifying proteins. In this review we discuss how PP1 affects the biochemistry and physiology of eukaryotic cells. The picture of PP1 that emerges from this analysis is that of a "green" enzyme that promotes the rational use of energy, the recycling of protein factors, and a reversal of the cell to a basal and/or energy-conserving state. Thus PP1 promotes a shift to the more energy-efficient fuels when nutrients are abundant and stimulates the storage of energy in the form of glycogen. PP1 also enables the relaxation of actomyosin fibers, the return to basal patterns of protein synthesis, and the recycling of transcription and splicing factors. In addition, PP1 plays a key role in the recovery from stress but promotes apoptosis when cells are damaged beyond repair. Furthermore, PP1 downregulates ion pumps and transporters in various tissues and ion channels that are involved in the excitation of neurons. Finally, PP1 promotes the exit from mitosis and maintains cells in the G1 or G2 phases of the cell cycle.
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Affiliation(s)
- Hugo Ceulemans
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Leuven, Belgium
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18
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Abstract
Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from lysine residues in both histone and non-histone proteins. They play a key role in the regulation of gene transcription and many other biological processes involving chromatin. Significantly, recent studies suggest that HDACs are critically involved in cell-cycle regulation, cell proliferation, differentiation, and in the development of human cancer. HDAC inhibitors currently are being exploited as potential anti-cancer agents. As expected for vital regulators of many cellular processes, the activities of HDACs are tightly controlled and precisely regulated by multiple mechanisms. The activities of most if not all HDACs are regulated by protein-protein interactions. In addition, many HDACs are regulated by post-translational modifications as well as by subcellular localization. Less studied, but perhaps equally important, is the regulation of some HDACs by control of expression, availability of cofactors, and by proteolytic processing. A complete understanding of how HDACs are regulated will contribute not only to our overall knowledge of chromatin structure and gene control, but will offer tremendous insight into approaches for developing therapeutic HDAC inhibitors with improved specificity.
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Affiliation(s)
- Nilanjan Sengupta
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
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19
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Brush MH, Guardiola A, Connor JH, Yao TP, Shenolikar S. Deactylase inhibitors disrupt cellular complexes containing protein phosphatases and deacetylases. J Biol Chem 2003; 279:7685-91. [PMID: 14670976 DOI: 10.1074/jbc.m310997200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Affinity isolation of protein serine/threonine phosphatases on the immobilized phosphatase inhibitor microcystin-LR identified histone deacetylase 1(HDAC1), HDAC6, and HDAC10 as novel components of cellular phosphatase complexes. Other HDACs, specifically HDAC2, -3, -4, and -5, were excluded from such complexes. In vitro biochemical studies showed that recombinant HDAC6, but not HDAC4, bound directly to the protein phosphatase (PP)1 catalytic subunit. No association was observed between HDAC6 and PP2A, another major protein phosphatase. PP1 binding was mapped to the second catalytic domain and adjacent C-terminal sequences in HDAC6, and treatment of cells with trichostatin A (TSA) disrupted endogenous HDAC6.PP1 complexes. Consistent with the inhibition of tubulin deactylase activity of HDAC6, TSA enhanced cellular tubulin acetylation, and acetylated tubulin was present in the PP1 complexes from TSA-treated cells. Trapoxin B, a weak HDAC6 inhibitor, and calyculin A, a cell-permeable phosphatase inhibitor, had no effect on the stability of the HDAC6.PP1 complexes or on tubulin acetylation. Mutations that inactivated HDAC6 prevented its incorporation into cellular PP1 complexes and suggested that when bound together both enzymes were active. Interestingly, TSA disrupted all the cellular HDAC.phosphatase complexes analyzed. This study provided new insight into the mechanism by which HDAC inhibitors elicited coordinate changes in cellular protein phosphorylation and acetylation and suggested that changes in these protein modifications at multiple subcellular sites may contribute to the known ability of HDAC inhibitors to suppress cell growth and transformation.
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Affiliation(s)
- Matthew H Brush
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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20
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Wysocka J, Herr W. The herpes simplex virus VP16-induced complex: the makings of a regulatory switch. Trends Biochem Sci 2003; 28:294-304. [PMID: 12826401 DOI: 10.1016/s0968-0004(03)00088-4] [Citation(s) in RCA: 226] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
When herpes simplex virus (HSV) infects human cells, it is able to enter two modes of infection: lytic and latent. A key activator of lytic infection is a virion protein called VP16, which, upon infection of a permissive cell, forms a transcriptional regulatory complex with two cellular proteins - the POU-domain transcription factor Oct-1 and the cell-proliferation factor HCF-1 - to activate transcription of the first set of expressed viral genes. This regulatory complex, called the VP16-induced complex, reveals mechanisms of combinatorial control of transcription. The activities of Oct-1 and HCF-1 - two important regulators of cellular gene expression and proliferation - illuminate strategies by which HSV might coexist with its host.
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21
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Julien E, Herr W. Proteolytic processing is necessary to separate and ensure proper cell growth and cytokinesis functions of HCF-1. EMBO J 2003; 22:2360-9. [PMID: 12743030 PMCID: PMC156000 DOI: 10.1093/emboj/cdg242] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
HCF-1 is a highly conserved and abundant chromatin-associated host cell factor required for transcriptional activation of herpes simplex virus immediate-early genes by the virion protein VP16. HCF-1 exists as a heterodimeric complex of associated N- (HCF-1(N)) and C- (HCF-1(C)) terminal subunits that result from proteolytic processing of a precursor protein. We have used small-interfering RNA (siRNA) to inactivate HCF-1 in an array of normal and transformed mammalian cells to identify its cellular functions. Our results show that HCF-1 is a broadly acting regulator of two stages of the cell cycle: exit from mitosis, where it ensures proper cytokinesis, and passage through the G(1) phase, where it promotes cell cycle progression. Proteolytic processing is necessary to separate and ensure these two HCF-1 activities, which are performed by separate HCF-1 subunits: the HCF-1(N) subunit promotes passage through the G(1) phase whereas the HCF-1(C) subunit is involved in proper exit from mitosis. These results suggest that HCF-1 links the regulation of exit from mitosis and the G(1) phase of cell growth, possibly to coordinate the reactivation of gene expression after mitosis.
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Affiliation(s)
- Eric Julien
- Cold Spring Harbor Laboratory, NY 11724, USA
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22
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Ajuh P, Chusainow J, Ryder U, Lamond AI. A novel function for human factor C1 (HCF-1), a host protein required for herpes simplex virus infection, in pre-mRNA splicing. EMBO J 2002; 21:6590-602. [PMID: 12456665 PMCID: PMC136956 DOI: 10.1093/emboj/cdf652] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human factor C1 (HCF-1) is needed for the expression of herpes simplex virus 1 (HSV-1) immediate-early genes in infected mammalian cells. Here, we provide evidence that HCF-1 is required for spliceosome assembly and splicing in mammalian nuclear extracts. HCF-1 interacts with complexes containing splicing snRNPs in uninfected mammalian cells and is a stable component of the spliceosome complex. We show that a missense mutation in HCF-1 in the BHK21 hamster cell line tsBN67, at the non-permissive temperature, inhibits the protein's interaction with U1 and U5 splicing snRNPs, causes inefficient spliceosome assembly and inhibits splicing. Transient expression of wild-type HCF-1 in tsBN67 cells restores splicing at the non-permissive temperature. The inhibition of splicing in tsBN67 cells correlates with the temperature-sensitive cell cycle arrest phenotype, suggesting that HCF-1-dependent splicing events may be required for cell cycle progression.
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Affiliation(s)
| | | | | | - Angus I. Lamond
- School of Life Sciences, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
Corresponding author e-mail:
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23
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Reilly PT, Wysocka J, Herr W. Inactivation of the retinoblastoma protein family can bypass the HCF-1 defect in tsBN67 cell proliferation and cytokinesis. Mol Cell Biol 2002; 22:6767-78. [PMID: 12215534 PMCID: PMC134044 DOI: 10.1128/mcb.22.19.6767-6778.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Owing to a single missense mutation in the cell proliferation factor HCF-1, the temperature-sensitive tsBN67 hamster cell line arrests proliferation at nonpermissive temperatures, primarily in a G(0)/G(1) state, and displays temperature-sensitive cytokinesis defects. The HCF-1 mutation in tsBN67 cells also causes a temperature-sensitive dissociation of HCF-1 from chromatin prior to cell proliferation arrest, suggesting that HCF-1-chromatin association is important for mammalian-cell proliferation. Here, we report that the simian virus 40 (SV40) early region, in particular, large T antigen (Tag), and the adenovirus oncoprotein E1A can rescue the tsBN67 cell proliferation defect at nonpermissive temperatures. The SV40 early region rescues the tsBN67 cell proliferation defect without restoring the HCF-1-chromatin association, indicating that these oncoproteins bypass a requirement for HCF-1 function. The SV40 early region also rescues the tsBN67 cytokinesis defect, suggesting that the roles of HCF-1 in cell proliferation and proper cytokinesis are intimately linked. The ability of SV40 Tag and adenovirus E1A to inactivate members of the pRb protein family-pRb, p107, and p130-is important for the bypass of HCF-1 function. These results suggest that HCF-1 regulates mammalian-cell proliferation and cytokinesis, at least in part, by either directly or indirectly opposing pRb family member function.
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Affiliation(s)
- Patrick T Reilly
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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24
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Piluso D, Bilan P, Capone JP. Host cell factor-1 interacts with and antagonizes transactivation by the cell cycle regulatory factor Miz-1. J Biol Chem 2002; 277:46799-808. [PMID: 12244100 DOI: 10.1074/jbc.m206226200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Human host cell factor-1 (HCF-1) is essential for cell cycle progression and is required, in conjunction with the herpes simplex virus transactivator VP16, for induction of viral immediate-early gene expression. We show here that HCF-1 directly binds to the Myc-interacting protein Miz-1, a transcription factor that induces cell cycle arrest at G(1), in part by directly stimulating expression of the cyclin-dependent kinase inhibitor p15(INK4b). A domain encompassing amino acids 750-836, contained within a subregion of HCF-1 required for cell cycle progression, was sufficient to bind Miz-1. Conversely, HCF-1 interacted with two separate regions in Miz-1: the N-terminal POZ domain and a C-terminal domain (residues 637-803) previously shown to harbor determinants for interaction with c-Myc and the coactivator p300. The latter functioned as a potent transactivation domain when tethered to DNA, indicating that HCF-1 targets a transactivation function in Miz-1. HCF-1 or a Miz-1-binding fragment of HCF-1 repressed transactivation by Gal4-Miz-1 in transfection assays. Moreover, HCF-1 repressed Miz-1-mediated transactivation of a reporter gene linked to the p15(INK4b) promoter. Protein/protein interaction studies and transient transfection assays demonstrated that HCF-1 interferes with recruitment of p300 to Miz-1, similar to what has been reported with c-Myc. Our findings identify Miz-1 as a novel HCF-1-interacting partner and illustrate cross-talk between these two proteins that may be of consequence to their respective functions in gene regulation and their opposing effects on the cell cycle.
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Affiliation(s)
- David Piluso
- Department of Biochemistry, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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25
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Scarr RB, Sharp PA. PDCD2 is a negative regulator of HCF-1 (C1). Oncogene 2002; 21:5245-54. [PMID: 12149646 DOI: 10.1038/sj.onc.1205647] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2002] [Revised: 05/03/2002] [Accepted: 05/07/2002] [Indexed: 11/10/2022]
Abstract
Temperature sensitive mutations in host cell factor 1 (HCF-1) arrest cells in the middle of the G1 phase of the cycle. We have shown that the highly conserved C-terminal WYF domain of HCF-1 protein interacts with the MYND domain of the PDCD2 protein. This inter-action is conserved between human HCF-1 and HCF-2 and the C. elegans HCF. Overexpression of PDCD2, which interacts with the N-CoR/mSin3A corepressor complexes, suppresses cotransfected HCF-1 complement-ation of a temperature lesion in the endogenous HCF-1 protein. Overexpression of domains of either PDCD2 or HCF-1, which should interfere with interactions between these two proteins, enhances the complementation.
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Affiliation(s)
- Rebecca B Scarr
- Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, MA 02139-4307, USA
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26
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Reilly PT, Herr W. Spontaneous reversion of tsBN67 cell proliferation and cytokinesis defects in the absence of HCF-1 function. Exp Cell Res 2002; 277:119-30. [PMID: 12061822 DOI: 10.1006/excr.2002.5551] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mammalian HCF-1 is a highly conserved and abundant chromatin-bound protein that plays a role in both herpes simplex virus (HSV) immediate-early (IE) gene transcription and cell proliferation. Its role in cell proliferation has been evidenced through the analysis of a temperature-sensitive hamster cell line called tsBN67. When placed at nonpermissive temperature, tsBN67 cells undergo a stable and reversible proliferation arrest after a lag of 36-48 h. This phenotype results from a single point mutation in HCF-1, which disrupts HCF-1 association with both chromatin and the HSV IE transactivator VP16 at nonpermissive temperature. Here, we report the isolation and characterization of spontaneous tsBN67 growth-revertant cells that are able to proliferate at nonpermissive temperatures. These cells retain the tsBN67 HCF-1 point mutation and grow in the absence of HCF-1 chromatin association, demonstrating that complete restoration of tsBN67 HCF-1 functions is not essential for cell proliferation. Phenotypic analysis of both mutant and revertant tsBN67 cells shows that, in addition to a cell proliferation defect, these cells display a conspicuous multinucleated phenotype in a significant population of arrested cells. This defect in cytokinesis is also a result of loss of HCF-1 function, suggesting that HCF-1 plays a role in cell exit from mitosis. The revertant tsBN67 cells display a coincident restoration of cell proliferation and suppression of the cytokinetic defect, suggesting that HCF-1 plays a shared role in cell proliferation and cytokinesis.
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27
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Abstract
The nucleus contains a large variety of protein phosphatases, which function in key processes such as cell-cycle progression, replication, transcription and RNA processing. Here, we review the pleiotropic action of nuclear protein phosphatases and focus in particular on the underlying signaling strategies. It appears that nuclear protein phosphatases can both mediate and antagonize signaling by protein kinases, sometimes as part of feedback loops. Some protein phosphatases shuttle between the cytoplasm and the nucleus, which enables them to act as signal transducers between both compartments. An emerging theme is the contribution of protein phosphatases to cycles of protein phosphorylation and dephosphorylation that steer the assembly and firing of molecular machines in the nucleus.
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Affiliation(s)
- Mathieu Bollen
- Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
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28
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Abstract
Protein phosphatase 1 (PP1) is a major eukaryotic protein serine/threonine phosphatase that regulates an enormous variety of cellular functions through the interaction of its catalytic subunit (PP1c) with over fifty different established or putative regulatory subunits. Most of these target PP1c to specific subcellular locations and interact with a small hydrophobic groove on the surface of PP1c through a short conserved binding motif – the RVxF motif – which is often preceded by further basic residues. Weaker interactions may subsequently enhance binding and modulate PP1 activity/specificity in a variety of ways. Several putative targeting subunits do not possess an RVxF motif but nevertheless interact with the same region of PP1c. In addition, several ‘modulator’ proteins bind to PP1c but do not possess a domain targeting them to a specific location. Most are potent inhibitors of PP1c and possess at least two sites for interaction with PP1c, one of which is identical or similar to the RVxF motif.Regulation of PP1c in response to extracellular and intracellular signals occurs mostly through changes in the levels, conformation or phosphorylation status of targeting subunits. Understanding of the mode of action of PP1c complexes may facilitate development of drugs that target particular PP1c complexes and thereby modulate the phosphorylation state of a very limited subset of proteins.
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Affiliation(s)
- Patricia T W Cohen
- Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD15EH, Scotland, UK.
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Peggie MW, MacKelvie SH, Bloecher A, Knatko EV, Tatchell K, Stark MJR. Essential functions of Sds22p in chromosome stability and nuclear localization of PP1. J Cell Sci 2002; 115:195-206. [PMID: 11801737 DOI: 10.1242/jcs.115.1.195] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sds22p is a conserved, leucine-rich repeat protein that interacts with the catalytic subunit of protein phosphatase 1 (PP1C) and which has been proposed to regulate one or more functions of PP1C during mitosis. Here we show that Saccharomyces cerevisiae Sds22p is a largely nuclear protein, most of which is present as a sTable 1:1 complex with yeast PP1C (Glc7p). Temperature-sensitive (Ts–) S. cerevisiae sds22 mutants show profound chromosome instability at elevated growth temperatures but do not confer a cell cycle stage-specific arrest. In the sds22-6 Ts– mutant, nuclear Glc7p is both reduced in level and aberrantly localized at 37°C and the interaction between Glc7p and Sds22p in vitro is reduced at higher temperatures, consistent with the in vivo Ts– growth defect. Like some glc7 mutations, sds22-6 can suppress the Ts– growth defect associated with ipl1-2, a loss of function mutation in a protein kinase that is known to work in opposition to PP1 on at least two nuclear substrates. This, together with reciprocal genetic interactions between GLC7 and SDS22, suggests that Sds22p functions positively with Glc7p to promote dephosphorylation of nuclear substrates required for faithful transmission of chromosomes during mitosis, and this role is at least partly mediated by effects of Sds22p on the nuclear distribution of Glc7p
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Affiliation(s)
- Mark W Peggie
- Division of Gene Regulation and Expression, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee, DD1 5EH, UK
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Wysocka J, Reilly PT, Herr W. Loss of HCF-1-chromatin association precedes temperature-induced growth arrest of tsBN67 cells. Mol Cell Biol 2001; 21:3820-9. [PMID: 11340173 PMCID: PMC87041 DOI: 10.1128/mcb.21.11.3820-3829.2001] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human HCF-1 is a large, highly conserved, and abundant nuclear protein that plays an important but unknown role in cell proliferation. It also plays a role in activation of herpes simplex virus immediate-early gene transcription by the viral regulatory protein VP16. A single proline-to-serine substitution in the HCF-1 VP16 interaction domain causes a temperature-induced arrest of cell proliferation in hamster tsBN67 cells and prevents transcriptional activation by VP16. We show here that HCF-1 is naturally bound to chromatin in uninfected cells through its VP16 interaction domain. HCF-1 is chromatin bound in tsBN67 cells at permissive temperature but dissociates from chromatin before tsBN67 cells stop proliferating at the nonpermissive temperature, suggesting that loss of HCF-1 chromatin association is the primary cause of the temperature-induced tsBN67 cell proliferation arrest. We propose that the role of HCF-1 in cell proliferation is to regulate gene transcription by associating with a multiplicity of DNA-bound transcription factors through its VP16 interaction domain.
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Affiliation(s)
- J Wysocka
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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