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Miguel-Hernández S, Zluhan-Martínez E, Garay-Arroyo A, Cabrera-Muñoz L, Hernández-Angeles A, Durán-Figueroa NV, Pérez-Koldenkova V, Ponce-Castañeda MV. In vivo movement of retinoblastoma-related protein (RBR) towards cytoplasm during mitosis in Arabidopsisthaliana. Differentiation 2024:100800. [PMID: 38987088 DOI: 10.1016/j.diff.2024.100800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 06/25/2024] [Accepted: 07/02/2024] [Indexed: 07/12/2024]
Abstract
Retinoblastoma protein is central in signaling networks of fundamental cell decisions such as proliferation and differentiation in all metazoans and cancer development. Immunostaining and biochemical evidence demonstrated that during interphase retinoblastoma protein is in the nucleus and is hypophosphorylated, and during mitosis is in the cytoplasm and is hyperphosphorylated. The purpose of this study was to visualize in vivo in a non-diseased tissue, the dynamic spatial and temporal nuclear exit toward the cytoplasm of this protein during mitosis and its return to the nucleus to obtain insights into its potential cytosolic functions. Using high-resolution time-lapse images from confocal microscopy, we tracked in vivo the ortholog in plants the RETINOBLASTOMA RELATED (RBR) protein tagged with Green Fluorescent Protein (GFP) in Arabidopsis thaliana's root. RBR protein exits from dense aggregates in the nucleus before chromosomes are in prophase in less than 2 min, spreading outwards as smaller particles projected throughout the cytosol during mitosis like a diffusive yet controlled event until telophase, when the daughter's nuclei form; RBR returns to the nuclei in coordination with decondensing chromosomal DNA forming new aggregates again in punctuated larger structures in each corresponding nuclei. We propose RBR diffused particles in the cytoplasm may function as a cytosolic sensor of incoming signals, thus coordinating re-aggregation with DNA is a mechanism by which any new incoming signals encountered by RBR may lead to a reconfiguration of the nuclear transcriptomic context. The small RBR diffused particles in the cytoplasm may preserve topologic-like properties allowing them to aggregate and restore their nuclear location, they may also be part of transient cytoplasmic storage of the cellular pre-mitotic transcriptional context, that once inside the nuclei may execute both the pre mitosis transcriptional context as well as new transcriptional instructions.
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Affiliation(s)
- Sergio Miguel-Hernández
- Laboratorio Nacional de Microscopía Avanzada de la Coordinación de Investigación en Salud, CMN SXXI Instituto Mexicano del Seguro Social, Ciudad de México, Mexico
| | - Estephania Zluhan-Martínez
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Depto. De Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Adriana Garay-Arroyo
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Depto. De Ecología Funcional, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Adriana Hernández-Angeles
- Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, Mexico
| | - Noé Valentín Durán-Figueroa
- Unidad Profesional Interdisciplinaria de Ingeniería y Biotecnología, Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Vadim Pérez-Koldenkova
- Laboratorio Nacional de Microscopía Avanzada de la Coordinación de Investigación en Salud, CMN SXXI Instituto Mexicano del Seguro Social, Ciudad de México, Mexico
| | - M Verónica Ponce-Castañeda
- Unidad de Investigación Médica en Enfermedades Infecciosas, Hospital de Pediatría, CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, Mexico; Facultad de Ciencias, Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
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Konagaya Y, Rosenthal D, Ratnayeke N, Fan Y, Meyer T. An intermediate Rb-E2F activity state safeguards proliferation commitment. Nature 2024; 631:424-431. [PMID: 38926571 PMCID: PMC11236703 DOI: 10.1038/s41586-024-07554-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 05/10/2024] [Indexed: 06/28/2024]
Abstract
Tissue repair, immune defence and cancer progression rely on a vital cellular decision between quiescence and proliferation1,2. Mammalian cells proliferate by triggering a positive feedback mechanism3,4. The transcription factor E2F activates cyclin-dependent kinase 2 (CDK2), which in turn phosphorylates and inactivates the E2F inhibitor protein retinoblastoma (Rb). This action further increases E2F activity to express genes needed for proliferation. Given that positive feedback can inadvertently amplify small signals, understanding how cells keep this positive feedback in check remains a puzzle. Here we measured E2F and CDK2 signal changes in single cells and found that the positive feedback mechanism engages only late in G1 phase. Cells spend variable and often extended times in a reversible state of intermediate E2F activity before committing to proliferate. This intermediate E2F activity is proportional to the amount of phosphorylation of a conserved T373 residue in Rb that is mediated by CDK2 or CDK4/CDK6. Such T373-phosphorylated Rb remains bound on chromatin but dissociates from it once Rb is hyperphosphorylated at many sites, which fully activates E2F. The preferential initial phosphorylation of T373 can be explained by its relatively slower rate of dephosphorylation. Together, our study identifies a primed state of intermediate E2F activation whereby cells sense external and internal signals and decide whether to reverse and exit to quiescence or trigger the positive feedback mechanism that initiates cell proliferation.
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Affiliation(s)
- Yumi Konagaya
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA.
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Laboratory for Quantitative Biology of Cell Fate Decision, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo, Japan.
| | - David Rosenthal
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA
| | - Nalin Ratnayeke
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yilin Fan
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Pathology and Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Tobias Meyer
- Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY, USA.
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
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3
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Sanidas I, Lawrence MS, Dyson NJ. Patterns in the tapestry of chromatin-bound RB. Trends Cell Biol 2024; 34:288-298. [PMID: 37648594 PMCID: PMC10899529 DOI: 10.1016/j.tcb.2023.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
The retinoblastoma protein (RB)-mediated regulation of E2F is a component of a highly conserved cell cycle machine. However, RB's tumor suppressor activity, like RB's requirement in animal development, is tissue-specific, context-specific, and sometimes appears uncoupled from cell proliferation. Detailed new information about RB's genomic distribution provides a new perspective on the complexity of RB function, suggesting that some of its functional specificity results from context-specific RB association with chromatin. Here we summarize recent evidence showing that RB targets different types of chromatin regulatory elements at different cell cycle stages. RB controls traditional RB/E2F targets prior to S-phase, but, when cells proliferate, RB redistributes to cell type-specific chromatin loci. We discuss the broad implications of the new data for RB research.
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Affiliation(s)
- Ioannis Sanidas
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
| | - Nicholas J Dyson
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA.
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Vadrot N, Ader F, Moulin M, Merlant M, Chapon F, Gandjbakhch E, Labombarda F, Maragnes P, Réant P, Rooryck C, Probst V, Donal E, Richard P, Ferreiro A, Buendia B. Abnormal Cellular Phenotypes Induced by Three TMPO/LAP2 Variants Identified in Men with Cardiomyopathies. Cells 2023; 12:337. [PMID: 36672271 PMCID: PMC9857342 DOI: 10.3390/cells12020337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
A single missense variant of the TMPO/LAP2α gene, encoding LAP2 proteins, has been associated with cardiomyopathy in two brothers. To further evaluate its role in cardiac muscle, we included TMPO in our cardiomyopathy diagnostic gene panel. A screening of ~5000 patients revealed three novel rare TMPO heterozygous variants in six males diagnosed with hypertrophic or dilated cardiomypathy. We identified in different cellular models that (1) the frameshift variant LAP2α p.(Gly395Glufs*11) induced haploinsufficiency, impeding cell proliferation and/or producing a truncated protein mislocalized in the cytoplasm; (2) the C-ter missense variant LAP2α p.(Ala240Thr) led to a reduced proximity events between LAP2α and the nucleosome binding protein HMGN5; and (3) the LEM-domain missense variant p.(Leu124Phe) decreased both associations of LAP2α/β with the chromatin-associated protein BAF and inhibition of the E2F1 transcription factor activity which is known to be dependent on Rb, partner of LAP2α. Additionally, the LAP2α expression was lower in the left ventricles of male mice compared to females. In conclusion, our study reveals distinct altered properties of LAP2 induced by these TMPO/LAP2 variants, leading to altered cell proliferation, chromatin structure or gene expression-regulation pathways, and suggests a potential sex-dependent role of LAP2 in myocardial function and disease.
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Affiliation(s)
- Nathalie Vadrot
- Basic and Translational Myology Laboratory, Université Paris Cité, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Flavie Ader
- APHP—Sorbonne Université, Unité Fonctionnelle de Cardiogénétique et Myogénétique Moléculaire, Service de Biochimie Métabolique, HU Pitié Salpêtrière—Charles Foix, F-75013 Paris, France
- INSERM, UMR_S 1166, Sorbonne Université, F-75005 Paris, France
- Faculté de Pharmacie Paris Descartes, Département 3, Université Paris Cité, F-75006 Paris, France
| | - Maryline Moulin
- Basic and Translational Myology Laboratory, Université Paris Cité, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Marie Merlant
- Basic and Translational Myology Laboratory, Université Paris Cité, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | | | - Estelle Gandjbakhch
- INSERM, UMR_S 1166, Sorbonne Université, F-75005 Paris, France
- Département de cardiologie, APHP—Sorbonne Université, HU Pitié Salpêtrière- Charles Foix, F-75610 Paris, France
| | - Fabien Labombarda
- Service de Cardiologie, CHU de Caen, Université de Caen Normandie, F-14000 Caen, France
| | - Pascale Maragnes
- Cardiologie pédiatrique, Service de pédiatrie, CHU de Caen, F-14000 Caen, France
| | - Patricia Réant
- Service de Cardiologie, Hôpital Haut Lévêque, CHU de Bordeaux, INSERM 1045, Université de Bordeaux, F-33000 Bordeaux, France
| | - Caroline Rooryck
- Service de Génétique Médicale, CHU Bordeaux, F-33000 Bordeaux, France
| | - Vincent Probst
- Centre de référence des maladies rythmiques cardiaques, CHU de Nantes, F-44000 Nantes, France
| | - Erwan Donal
- Centre Cardio-Pneumologique, CHU de Rennes Hôpital de Pontchaillou, F-35000 Rennes, France
| | - Pascale Richard
- APHP—Sorbonne Université, Unité Fonctionnelle de Cardiogénétique et Myogénétique Moléculaire, Service de Biochimie Métabolique, HU Pitié Salpêtrière—Charles Foix, F-75013 Paris, France
- INSERM, UMR_S 1166, Sorbonne Université, F-75005 Paris, France
| | - Ana Ferreiro
- Basic and Translational Myology Laboratory, Université Paris Cité, BFA, UMR 8251, CNRS, F-75013 Paris, France
- APHP, Centre de référence des Maladies Neuromusculaires, Institut de Myologie, Neuromyology Department, CHU Pitié Salpêtrière—Charles Foix, F-75013 Paris, France
| | - Brigitte Buendia
- Basic and Translational Myology Laboratory, Université Paris Cité, BFA, UMR 8251, CNRS, F-75013 Paris, France
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Kim S, Leong A, Kim M, Yang HW. CDK4/6 initiates Rb inactivation and CDK2 activity coordinates cell-cycle commitment and G1/S transition. Sci Rep 2022; 12:16810. [PMID: 36207346 PMCID: PMC9546874 DOI: 10.1038/s41598-022-20769-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 09/19/2022] [Indexed: 02/04/2023] Open
Abstract
External signaling controls cell-cycle entry until cells irreversibly commit to the cell cycle to ensure faithful DNA replication. This process is tightly regulated by cyclin-dependent kinases (CDKs) and the retinoblastoma protein (Rb). Here, using live-cell sensors for CDK4/6 and CDK2 activities, we propose that CDK4/6 initiates Rb inactivation and CDK2 activation, which coordinates the timing of cell-cycle commitment and sequential G1/S transition. Our data show that CDK4/6 activation induces Rb inactivation and thereby E2F activation, driving a gradual increase in CDK2 activity. We found that rapid CDK4/6 inhibition can reverse cell-cycle entry until CDK2 activity reaches to high levels. This suggests that high CDK2 activity is required to initiate CDK2-Rb positive feedback and CDK4/6-indpendent cell-cycle progression. Since CDK2 activation also facilitates initiation of DNA replication, the timing of CDK2-Rb positive feedback is coupled with the G1/S transition. Our experiments, which acutely increased CDK2 activity by cyclin E1 overexpression, indicate that cells commit to the cell cycle before triggering DNA replication. Together, our data suggest that CDK4/6 inactivates Rb to begin E2F and CDK2 activation, and high CDK2 activity is necessary and sufficient to generate a bistable switch for Rb phosphorylation before DNA replication. These findings highlight how cells initiate the cell cycle and subsequently commit to the cell cycle before the G1/S transition.
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Affiliation(s)
- Sungsoo Kim
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Alessandra Leong
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Minah Kim
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA.
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, 10032, USA.
| | - Hee Won Yang
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA.
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, 10032, USA.
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6
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Sanidas I, Lee H, Rumde PH, Boulay G, Morris R, Golczer G, Stanzione M, Hajizadeh S, Zhong J, Ryan MB, Corcoran RB, Drapkin BJ, Rivera MN, Dyson NJ, Lawrence MS. Chromatin-bound RB targets promoters, enhancers, and CTCF-bound loci and is redistributed by cell-cycle progression. Mol Cell 2022; 82:3333-3349.e9. [PMID: 35981542 PMCID: PMC9481721 DOI: 10.1016/j.molcel.2022.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 05/19/2022] [Accepted: 07/20/2022] [Indexed: 02/06/2023]
Abstract
The interaction of RB with chromatin is key to understanding its molecular functions. Here, for first time, we identify the full spectrum of chromatin-bound RB. Rather than exclusively binding promoters, as is often described, RB targets three fundamentally different types of loci (promoters, enhancers, and insulators), which are largely distinguishable by the mutually exclusive presence of E2F1, c-Jun, and CTCF. While E2F/DP facilitates RB association with promoters, AP-1 recruits RB to enhancers. Although phosphorylation in CDK sites is often portrayed as releasing RB from chromatin, we show that the cell cycle redistributes RB so that it enriches at promoters in G1 and at non-promoter sites in cycling cells. RB-bound promoters include the classic E2F-targets and are similar between lineages, but RB-bound enhancers associate with different categories of genes and vary between cell types. Thus, RB has a well-preserved role controlling E2F in G1, and it targets cell-type-specific enhancers and CTCF sites when cells enter S-phase.
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Affiliation(s)
- Ioannis Sanidas
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Hanjun Lee
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Purva H Rumde
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Gaylor Boulay
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
| | - Robert Morris
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Gabriel Golczer
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Marcelo Stanzione
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Soroush Hajizadeh
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Jun Zhong
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Meagan B Ryan
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Ryan B Corcoran
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA
| | - Benjamin J Drapkin
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA; UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
| | - Miguel N Rivera
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
| | - Nicholas J Dyson
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA.
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Building 149 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA.
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7
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Mayangsari Y, Sugimachi N, Xu W, Mano C, Tanaka Y, Ueda O, Sakuta T, Suzuki Y, Yamamoto Y, Suzuki T. 3,5,7,3',4'-Pentamethoxyflavone Enhances the Barrier Function through Transcriptional Regulation of the Tight Junction in Human Intestinal Caco-2 Cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:10174-10183. [PMID: 34449209 DOI: 10.1021/acs.jafc.1c04295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The intestinal tight junction (TJ) barrier plays a pivotal role in the regulation of intestinal homeostasis. This study investigated the effects of 3,5,7,3',4'-pentamethoxyflavone (PMF), a major polymethoxyflavone found in black ginger, on TJ barrier regulation using intestinal Caco-2 cells. PMF treatment enhanced the TJ barrier integrity in Caco-2 cells, indicated by increased transepithelial electrical resistance (control, 1261 ± 36 Ω·cm2; 100 μM PMF, 1383 ± 55 Ω·cm2 at 48 h, p < 0.05) and decreased permeability to fluorescein-conjugated dextran (control, 24.2 ± 1.8 pmol/(cm2 × h); 100 μM PMF, 18.6 ± 1.0 pmol/(cm2 × h), p < 0.05). Immunoblot analysis revealed that PMF increased the cytoskeletal association and cellular expression of the TJ proteins, zonula occludens-1, claudin-3, and claudin-4 (e.g., occludin; control, 1.00 ± 0.2; 100 μM PMF, 3.69 ± 0.86 at 48 h, p < 0.05). Quantitative reverse transcriptase-polymerase chain reaction analysis and a luciferase promoter assay showed that PMF enhanced the transcription of occludin, claudin-3, and claudin-4. The promoter assay with site-directed mutagenesis indicated that PMF-induced occludin and claudin-3 transcription was mediated by transcription factors, KLF5 and EGR1, respectively, while PMF activated claudin-4 transcription through GATA1 and AP1. Taken together, the transcriptional regulation of TJ proteins is involved in PMF-mediated promotion of the intestinal barrier in vitro.
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Affiliation(s)
- Yunika Mayangsari
- Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
- Faculty of Agricultural Technology, Gadjah Mada University, Jl. Flora No 1, Depok, Sleman, Yogyakarta 55281, Indonesia
| | - Natsumi Sugimachi
- School of Applied Biological Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
| | - Wenxi Xu
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
| | - Chinatsu Mano
- Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama 220-0011, Japan
| | - Yuki Tanaka
- Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama 220-0011, Japan
| | - Osamu Ueda
- Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama 220-0011, Japan
| | - Tomohiro Sakuta
- Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama 220-0011, Japan
| | - Yoshiharu Suzuki
- Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama 220-0011, Japan
| | - Yoshinari Yamamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
| | - Takuya Suzuki
- Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
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8
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Chen C, Huang FW, Huang SS, Huang JS. IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating type V TGF-β receptor (TβR-V)-mediated tumor suppressor signaling. FASEB Bioadv 2021; 3:709-729. [PMID: 34485840 PMCID: PMC8409558 DOI: 10.1096/fba.2021-00016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/06/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
The TGF-β type V receptor (TβR-V) mediates growth inhibition by IGFBP-3 and TGF-β in epithelial cells and loss of TβR-V expression in these cells leads to development of carcinoma. The mechanisms by which TβR-V mediates growth inhibition (tumor suppressor) signaling remain elusive. Previous studies revealed that IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating TβR-V-mediated IRS-1/2-dependent activation and cytoplasm-to-nucleus translocation of IGFBP-3- or TGF-β-stimulated protein phosphatase (PPase), resulting in dephosphorylation of pRb-related proteins (p107, p130) or pRb, and growth arrest. To define the signaling, we characterized/identified the IGFBP-3- and TGF-β-stimulated PPases in cell lysates and nucleus fractions in Mv1Lu cells treated with IGFBP-3 and TGF-β, using a cell-free assay with 32P-labeled casein as a substrate. Both IGFBP-3- and TGF-β-stimulated PPase activities in cell lysates are abolished when cells are co-treated with TGF-β/IGFBP-3 antagonist or RAP (LRP-1/TβR-V antagonist). However, the IGFBP-3-stimulated PPase activity, but not TGF-β-stimulated PPase activity, is sensitive to inhibition by okadaic acid (OA). In addition, OA or PP2Ac siRNA reverses IGFBP-3 growth inhibition, but not TGF-β growth inhibition, in Mv1Lu and 32D cells. These suggest that IGFBP-3- and TGF-β-stimulated PPases are identical to PP2A and PP1, respectively. By Western blot/phosphorimager/immunofluorescence-microscopy analyses, IGFBP-3 and TGF-β stimulate TβR-V-mediated IRS-2-dependent activation and cytoplasm-to-nucleus translocation of PP2Ac and PP1c, resulting in dephosphorylation of p130/p107 and pRb, respectively, and growth arrest. Small molecule TGF-β enhancers, which potentiate TGF-β growth inhibition by enhancing TβR-I-TβR-II-mediated canonical signaling and thus activating TβR-V-mediated tumor suppressor signaling cascade (TβR-V/IRS-2/PP1/pRb), could be used to prevent and treat carcinoma.
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Affiliation(s)
- Chun‐Lin Chen
- Department of Biological ScienceNational Sun Yat‐sen UniversityKaohsiungTaiwan
- Departments of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMOUSA
| | - Franklin W. Huang
- Division of Hematology and OncologyDepartment of MedicineUniversity of CaliforniaSan FranciscoCAUSA
| | | | - Jung San Huang
- Departments of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMOUSA
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9
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NIR promotes progression of colorectal cancer through regulating RB. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118856. [PMID: 32931817 DOI: 10.1016/j.bbamcr.2020.118856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 08/21/2020] [Accepted: 09/09/2020] [Indexed: 01/05/2023]
Abstract
NIR, a novel INHAT, negatively regulates the transcription activity of tumor repressor p53. However, if NIR functions in the tumorigenesis dependent on the regulation of p53 remains unknown. Here, we report that NIR promotes progression of colorectal cancer (CRC) through regulating RB function. Firstly, we found that NIR expression is upregulated in the human CRC tissues and significantly associated with the poor outcome of the patients. Sequence alignment shows that NIR contains an RB-binding motif LxCxE in its INHAT-2 domain. We demonstrate that NIR interacts with RB via INHAT-2 in CRC cells and promotes RB degradation through proteasome-mediated pathway. Further, either full-length GFP-NIR or GFP-NIR-INHAT2 facilitates poly-ubiquitination of RB. In addition, NIR inhibits RB acetylation by INHAT-2, suggesting NIR might promote RB degradation through inhibiting RB acetylation. Importantly, endogenous NIR is downregulated upon DNA damage, which is consistent with the upregulation of total level and acetylation of RB. We further show that Flag-NIR inhibits DNA damage-induced RB acetylation. Thus, downregulation of NIR might contribute to maintain the cellular homeostasis under DNA damage. Consequently, depletion of NIR inhibits cell proliferation and tumor growth in mouse xenografts. Taken together, we demonstrate that NIR promotes CRC progression partially through inhibiting RB acetylation and promoting RB degradation. Targeting NIR may provide a potential therapeutic strategy for NIR-upregulated CRC patients.
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10
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Rein ID, Notø HØ, Bostad M, Huse K, Stokke T. Cell Cycle Analysis and Relevance for Single-Cell Gating in Mass Cytometry. Cytometry A 2020; 97:832-844. [PMID: 31943748 DOI: 10.1002/cyto.a.23960] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 12/10/2019] [Accepted: 12/16/2019] [Indexed: 12/21/2022]
Abstract
Cell cycle analysis by mass cytometry (MC) is hampered by the poor resolution of the Iridium-labeled DNA intercalator compared to DNA-specific fluorescent dyes. We report here a minimum cell cycle panel for MC consisting of Ir-intercalator (DNA content), IdU (S phase), anti-pS28HistoneH3 (mitosis), anti-CDT1 (G1 phase) and anti-Geminin (non-G1 phases). Cell cycle distributions obtained by MC were not significantly different from fluorescence flow cytometry results (r2 = 0.98, P < 0.001). Further subdivision of the G1 and G2 phases could be done with anti-pS780RB1 (late G1 ) and anti-PLK1 (late G2 ), respectively. A disadvantage of MC is that aggregates of cells cannot easily be removed while retaining all single cells. We have developed an analysis pipeline including unsupervised clustering by FlowSOM and subsequent single-cell gating. When performed on cells stained with the cell cycle panel, this analysis pipeline successfully identified debris, dead/apoptotic cells, nonsingle-cell populations and the major cell cycle phases. The presented cell cycle panel and analysis pipeline thus achieves true single-cell analysis at the same time as any additional channels in the panel are open for phenotyping and cell cycle-resolved expression or modification analysis. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry.
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Affiliation(s)
- Idun D Rein
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Heidi Ø Notø
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Monica Bostad
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Kanutte Huse
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Department of Cancer Immunology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- K.G. Jebsen Centre for B cell malignancies, University of Oslo, Oslo, Norway
| | - Trond Stokke
- Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
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11
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Chung M, Liu C, Yang HW, Köberlin MS, Cappell SD, Meyer T. Transient Hysteresis in CDK4/6 Activity Underlies Passage of the Restriction Point in G1. Mol Cell 2019; 76:562-573.e4. [PMID: 31543423 DOI: 10.1016/j.molcel.2019.08.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 06/04/2019] [Accepted: 08/21/2019] [Indexed: 10/26/2022]
Abstract
Cells escape the need for mitogens at a restriction point several hours before entering S phase. The restriction point has been proposed to result from CDK4/6 initiating partial Rb phosphorylation to trigger a bistable switch whereby cyclin E-CDK2 and Rb mutually reinforce each other to induce Rb hyperphosphorylation. Here, using single-cell analysis, we unexpectedly found that cyclin E/A-CDK activity can only maintain Rb hyperphosphorylation starting at the onset of S phase and that CDK4/6 activity, but not cyclin E/A-CDK activity, is required to hyperphosphorylate Rb throughout G1 phase. Mitogen removal in G1 results in a gradual loss of CDK4/6 activity with a high likelihood of cells sustaining Rb hyperphosphorylation until S phase, at which point cyclin E/A-CDK activity takes over. Thus, it is short-term memory, or transient hysteresis, in CDK4/6 activity following mitogen removal that sustains Rb hyperphosphorylation, demonstrating a probabilistic rather than an irreversible molecular mechanism underlying the restriction point.
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Affiliation(s)
- Mingyu Chung
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA
| | - Chad Liu
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA
| | - Hee Won Yang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Marielle S Köberlin
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA
| | - Steven D Cappell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA; Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Tobias Meyer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Clark Building W200, Stanford, CA 94305, USA.
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12
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Alvarado-Kristensson M, Rosselló CA. The Biology of the Nuclear Envelope and Its Implications in Cancer Biology. Int J Mol Sci 2019; 20:E2586. [PMID: 31137762 PMCID: PMC6566445 DOI: 10.3390/ijms20102586] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 05/07/2019] [Accepted: 05/25/2019] [Indexed: 12/18/2022] Open
Abstract
The formation of the nuclear envelope and the subsequent compartmentalization of the genome is a defining feature of eukaryotes. Traditionally, the nuclear envelope was purely viewed as a physical barrier to preserve genetic material in eukaryotic cells. However, in the last few decades, it has been revealed to be a critical cellular component in controlling gene expression and has been implicated in several human diseases. In cancer, the relevance of the cell nucleus was first reported in the mid-1800s when an altered nuclear morphology was observed in tumor cells. This review aims to give a current and comprehensive view of the role of the nuclear envelope on cancer first by recapitulating the changes of the nuclear envelope during cell division, second, by reviewing the role of the nuclear envelope in cell cycle regulation, signaling, and the regulation of the genome, and finally, by addressing the nuclear envelope link to cell migration and metastasis and its use in cancer prognosis.
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Affiliation(s)
- Maria Alvarado-Kristensson
- Molecular Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, 20502 Malmö, Sweden.
| | - Catalina Ana Rosselló
- Laboratory of Molecular Cell Biomedicine, University of the Balearic Islands, 07121 Palma de Mallorca, Spain.
- Lipopharma Therapeutics, Isaac Newton, 07121 Palma de Mallorca, Spain.
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13
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Zhang F, Liang D, Lin X, Zou Z, Sun R, Wang X, Liang X, Kaye KM, Lan K. NDRG1 facilitates the replication and persistence of Kaposi's sarcoma-associated herpesvirus by interacting with the DNA polymerase clamp PCNA. PLoS Pathog 2019; 15:e1007628. [PMID: 30811506 PMCID: PMC6411202 DOI: 10.1371/journal.ppat.1007628] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/11/2019] [Accepted: 02/08/2019] [Indexed: 02/07/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) latently infects host cells and establishes lifelong persistence as an extra-chromosomal episome in the nucleus. To persist in proliferating cells, the viral genome typically replicates once per cell cycle and is distributed into daughter cells. This process involves host machinery utilized by KSHV, however the underlying mechanisms are not fully elucidated. In present study, we found that N-Myc downstream regulated gene 1 (NDRG1), a cellular gene known to be non-detectable in primary B cells and endothelial cells which are the major cell types for KSHV infection in vivo, was highly upregulated by KSHV in these cells. We further demonstrated that the high expression of NDRG1 was regulated by latency-associated nuclear antigen (LANA), the major viral latent protein which tethers the viral genome to host chromosome and plays an essential role in viral genome maintenance. Surprisingly, knockdown of NDRG1 in KSHV latently infected cells resulted in a significant decrease of viral genome copy number in these cells. Interestingly, NDRG1 can directly interact with proliferating cell nuclear antigen (PCNA), a cellular protein which functions as a DNA polymerase clamp during DNA replication. Intriguingly, we found that NDRG1 forms a complex with LANA and PCNA and serves as a scaffold protein bridging these two proteins. We further demonstrated that NDRG1 is critical for mediating LANA to recruit PCNA onto terminal repeat (TR) of KSHV genome, and facilitates viral DNA replication and episome persistence. Taken together, our findings suggest that NDRG1 plays an important role in KSHV viral genome replication, and provide new clues for understanding of KSHV persistence.
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Affiliation(s)
- Fang Zhang
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Deguang Liang
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Xiaoxi Lin
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Zhe Zou
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Rui Sun
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Xing Wang
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Xiaozhen Liang
- CAS Key Laboratory of Molecular Virology & Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Kenneth M. Kaye
- Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Ke Lan
- State Key Laboratory of Virology, College of Life Sciences, Medical Research Institute, Wuhan University, Wuhan, China
- * E-mail:
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14
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Russell DS, Jaworski L, Kisseberth WC. Immunohistochemical detection of p53, PTEN, Rb, and p16 in canine osteosarcoma using tissue microarray. J Vet Diagn Invest 2018; 30:504-509. [PMID: 29629647 DOI: 10.1177/1040638718770239] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Although inactivating mutations of tumor suppressor genes are well described in cell lines of canine osteosarcoma (OS), expression of tumor suppressor proteins in spontaneous disease is poorly characterized. We determined the immunohistochemical expression of p53, PTEN, Rb, and p16 in a large cohort of dogs with OS. Formalin-fixed, paraffin-embedded samples of canine OS were analyzed retrospectively. Primary tumor samples from 145 dogs, collected between 2003 and 2008, were evaluated by tissue microarray. Streptavidin-biotin complex immunohistochemistry was performed using monoclonal antibodies for Rb and PTEN and polyclonal antibodies for p16 and p53. The average age of dogs was 7.6 y, and 118 of 145 (81%) were purebred. Most commonly represented purebreds were Greyhound (23%), Rottweiler (11%), and Labrador Retriever (10%). Immunohistochemical detection of p53, PTEN, Rb, and p16 was 81%, 61%, 66%, and 66%, respectively. The staining pattern for p16 was primarily cytoplasmic; the predominant pattern for PTEN, Rb, and p53 was cytoplasmic and nuclear. Exclusively cytoplasmic staining was noted in 19% of samples positive for p53 and 8% of samples positive for Rb. Kaplan-Meier curves showed that protein expression was not associated with significant differences in overall survival ( p > 0.191). We documented heterogeneity in both immunostaining and subcellular localization of tumor suppressor proteins, providing further characterization of canine OS.
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Affiliation(s)
- Duncan S Russell
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR (Russell).,Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH (Jaworski, Kisseberth)
| | - Lauren Jaworski
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR (Russell).,Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH (Jaworski, Kisseberth)
| | - William C Kisseberth
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR (Russell).,Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH (Jaworski, Kisseberth)
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15
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Serebryannyy L, Misteli T. Protein sequestration at the nuclear periphery as a potential regulatory mechanism in premature aging. J Cell Biol 2017; 217:21-37. [PMID: 29051264 PMCID: PMC5748986 DOI: 10.1083/jcb.201706061] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/10/2017] [Accepted: 08/17/2017] [Indexed: 12/19/2022] Open
Abstract
Serebryannyy and Misteli provide a perspective on how protein sequestration at the inner nuclear membrane and nuclear lamina might influence aging. Despite the extensive description of numerous molecular changes associated with aging, insights into the driver mechanisms of this fundamental biological process are limited. Based on observations in the premature aging syndrome Hutchinson–Gilford progeria, we explore the possibility that protein regulation at the inner nuclear membrane and the nuclear lamina contributes to the aging process. In support, sequestration of nucleoplasmic proteins to the periphery impacts cell stemness, the response to cytotoxicity, proliferation, changes in chromatin state, and telomere stability. These observations point to the nuclear periphery as a central regulator of the aging phenotype.
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Affiliation(s)
| | - Tom Misteli
- National Cancer Institute, National Institutes of Health, Bethesda, MD
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16
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Zhang J, Xu K, Liu P, Geng Y, Wang B, Gan W, Guo J, Wu F, Chin YR, Berrios C, Lien EC, Toker A, DeCaprio JA, Sicinski P, Wei W. Inhibition of Rb Phosphorylation Leads to mTORC2-Mediated Activation of Akt. Mol Cell 2016; 62:929-942. [PMID: 27237051 DOI: 10.1016/j.molcel.2016.04.023] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 12/07/2015] [Accepted: 04/21/2016] [Indexed: 12/23/2022]
Abstract
The retinoblastoma (Rb) protein exerts its tumor suppressor function primarily by inhibiting the E2F family of transcription factors that govern cell-cycle progression. However, it remains largely elusive whether the hyper-phosphorylated, non-E2F1-interacting form of Rb has any physiological role. Here we report that hyper-phosphorylated Rb directly binds to and suppresses the function of mTORC2 but not mTORC1. Mechanistically, Rb, but not p107 or p130, interacts with Sin1 and blocks the access of Akt to mTORC2, leading to attenuated Akt activation and increased sensitivity to chemotherapeutic drugs. As such, inhibition of Rb phosphorylation by depleting cyclin D or using CDK4/6 inhibitors releases Rb-mediated mTORC2 suppression. This, in turn, leads to elevated Akt activation to confer resistance to chemotherapeutic drugs in Rb-proficient cells, which can be attenuated with Akt inhibitors. Therefore, our work provides a molecular basis for the synergistic usage of CDK4/6 and Akt inhibitors in treating Rb-proficient cancer.
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Affiliation(s)
- Jinfang Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Kai Xu
- Department of Otolaryngology-Head and Neck Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, P.R. China.,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Pengda Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Yan Geng
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Bin Wang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Department of Gastroenterology, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, 400042, P. R. China
| | - Wenjian Gan
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Fei Wu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.,Department of Urology, Huashan Hospital, Fudan University, Shanghai, 200040, P.R. China
| | - Y Rebecca Chin
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Christian Berrios
- Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Evan C Lien
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Alex Toker
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - James A DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Piotr Sicinski
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
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17
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Metabolic profiling of hematopoietic stem and progenitor cells during proliferation and differentiation into red blood cells. N Biotechnol 2015; 33:179-86. [PMID: 26013297 DOI: 10.1016/j.nbt.2015.05.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 05/05/2015] [Accepted: 05/16/2015] [Indexed: 12/31/2022]
Abstract
An understanding of the metabolic profile of cell proliferation and differentiation should support the optimization of culture conditions for hematopoietic stem and progenitor cell (HSPC) proliferation, differentiation, and maturation into red blood cells. We have evaluated the key metabolic parameters during each phase of HSPC culture for red blood cell production in serum-supplemented (SS) and serum-free (SF) conditions. A simultaneous decrease in growth rate, total protein content, cell size, and the percentage of cells in the S/G2 phase of cell cycle, as well as an increase in the percentage of cells with a CD71(-)/GpA(+) surface marker profile, indicates HSPC differentiation into red blood cells. Compared with proliferating HSPCs, differentiating HSPCs showed significantly lower glucose and glutamine consumption rates, lactate and ammonia production rates, and amino acid consumption and production rates in both SS and SF conditions. Furthermore, extracellular acidification was associated with late proliferation phase, suggesting a reduced cellular metabolic rate during the transition from proliferation to differentiation. Under both SS and SF conditions, cells demonstrated a high metabolic rate with a mixed metabolism of both glycolysis and oxidative phosphorylation (OXPHOS) in early and late proliferation, an increased dependence on OXPHOS activity during differentiation, and a shift to glycolytic metabolism only during maturation phase. These changes indicate that cell metabolism may have an important impact on the ability of HSPCs to proliferate and differentiate into red blood cells.
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18
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Pin1 inhibits PP2A-mediated Rb dephosphorylation in regulation of cell cycle and S-phase DNA damage. Cell Death Dis 2015; 6:e1640. [PMID: 25675300 PMCID: PMC4669794 DOI: 10.1038/cddis.2015.3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 02/05/2023]
Abstract
Inactivation of the retinoblastoma protein (Rb) has a key role in tumorigenesis. It is well established that Rb function is largely regulated by a dynamic balance of phosphorylation and dephosphorylation. Although much research has been done to understand the mechanisms and function of RB phosphorylation, the regulation of Rb dephosphorylation is still not well understood. In this study, we demonstrate that Pin1 has an important role in the regulation of Rb function in cell cycle progression and S-phase checkpoint upon DNA damage. We show that the Rb C-pocket directly binds to the Pin1 WW domain in vitro and in vivo, and that the phosphorylation of Rb C-pocket by G1/S Cyclin/Cyclin-dependent kinase complexes is critical for mediating this interaction. We further show that Rb-mediated cell cycle arrest and Rb-induced premature cellular senescence are effectively inhibited by Pin1 expression. In addition, DNA damage induces Rb dephosphorylation in a PP2A-dependent manner, and this process is inhibited by Pin1. Furthermore, the overexpression of Pin1 promotes Rb hyperphosphorylation upon S-phase DNA damage. Importantly, both the Pin1 WW domain and isomerase activity are required for its effect on S-phase checkpoint. Moreover, the overexpression of Pin1 is correlated with Rb hyperphosphorylation in breast cancer biopsies. These results indicate that Pin1 has a critical role in the modulation of Rb function by the regulation of Rb dephosphorylation, which may have an important pathological role in cancer development.
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19
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Suppression of BRCA1 sensitizes cells to proteasome inhibitors. Cell Death Dis 2014; 5:e1580. [PMID: 25522274 PMCID: PMC4649846 DOI: 10.1038/cddis.2014.537] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 02/08/2023]
Abstract
BRCA1 is a multifunctional protein best known for its role in DNA repair and association with breast and ovarian cancers. To uncover novel biologically significant molecular functions of BRCA1, we tested a panel of 198 approved and experimental drugs to inhibit growth of MDA-MB-231 breast cancer cells depleted for BRCA1 by siRNA. 26S proteasome inhibitors bortezomib and carfilzomib emerged as a new class of selective BRCA1-targeting agents. The effect was confirmed in HeLa and U2OS cancer cell lines using two independent siRNAs, and in mouse embryonic stem (ES) cells with inducible deletion of Brca1. Bortezomib treatment did not cause any increase in nuclear foci containing phosphorylated histone H2AX, and knockdown of BRCA2 did not entail sensitivity to bortezomib, suggesting that the DNA repair function of BRCA1 may not be directly involved. We found that a toxic effect of bortezomib on BRCA1-depleted cells is mostly due to deregulated cell cycle checkpoints mediated by RB1-E2F pathway and 53BP1. Similar to BRCA1, depletion of RB1 also conferred sensitivity to bortezomib, whereas suppression of E2F1 or 53BP1 together with BRCA1 reduced induction of apoptosis after bortezomib treatment. A gene expression microarray study identified additional genes activated by bortezomib treatment only in the context of inactivation of BRCA1 including a critical involvement of the ERN1-mediated unfolded protein response. Our data indicate that BRCA1 has a novel molecular function affecting cell cycle checkpoints in a manner dependent on the 26S proteasome activity.
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20
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Hattori T, Uchida C, Takahashi H, Yamamoto N, Naito M, Taya Y. Distinct and site-specific phosphorylation of the retinoblastoma protein at serine 612 in differentiated cells. PLoS One 2014; 9:e86709. [PMID: 24466208 PMCID: PMC3897739 DOI: 10.1371/journal.pone.0086709] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/11/2013] [Indexed: 01/01/2023] Open
Abstract
The retinoblastoma susceptibility protein (pRB) is a phosphoprotein that regulates cell cycle progression at the G1/S transition. In quiescent and early G1 cells, pRB predominantly exists in the active hypophosphorylated form. The cyclin/cyclin-dependent protein kinase complexes phosphorylate pRB at the late G1 phase to inactivate pRB. This event leads to the dissociation and activation of E2F family transcriptional factors. At least 12 serine/threonine residues in pRB are phosphorylated in vivo. Although there have been many reports describing bulk phosphorylation of pRB, detail research describing the function of each phosphorylation site remains unknown. Besides its G1/S inhibitory function, pRB is involved in differentiation, prevention of cell death and control of tissue fate. To uncover the function of phosphorylation of pRB in various cellular conditions, we have been investigating phosphorylation of each serine/threonine residue in pRB with site-specific phospho-serine/threonine antibodies. Here we demonstrate that pRB is specifically phosphorylated at Ser612 in differentiated cells in a known kinase-independent manner. We also found that pRB phosphorylated at Ser612 still associates with E2F-1 and tightly binds to nuclear structures including chromatin. Moreover, expression of the Ser612Ala mutant pRB failed to induce differentiation. The findings suggest that phosphorylation of Ser612 provides a distinct function that differs from the function of phosphorylation of other serine/threonine residues in pRB.
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Affiliation(s)
- Takayuki Hattori
- Division of Biochemistry and Molecular Biology, National Institute of Health Sciences, Setagaya-ku, Tokyo, Japan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- * E-mail:
| | - Chiharu Uchida
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- Research Equipment Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hirotaka Takahashi
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Naoki Yamamoto
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Mikihiko Naito
- Division of Biochemistry and Molecular Biology, National Institute of Health Sciences, Setagaya-ku, Tokyo, Japan
| | - Yoichi Taya
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
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21
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RB and Lamins in Cell Cycle Regulation and Aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:127-42. [DOI: 10.1007/978-1-4899-8032-8_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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22
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Faust D, Kletting S, Ueberham E, Dietrich C. Aryl hydrocarbon receptor-dependent cell cycle arrest in isolated mouse oval cells. Toxicol Lett 2013; 223:73-80. [DOI: 10.1016/j.toxlet.2013.08.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 08/26/2013] [Accepted: 08/28/2013] [Indexed: 12/16/2022]
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23
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Abstract
Cyclin-dependent kinases (Cdks) drive cell cycle progression in all eukaryotes. Yeasts have a single major Cdk that mediates distinct cell cycle transitions via association with different cyclins. The closest homolog in mammals, Cdk1, drives mitosis. Mammals have additional Cdks-Cdk2, Cdk4, and Cdk6-that represent the major Cdks activated during interphase (iCdks). A large body of evidence has accrued that suggests that activation of iCdks dictates progression though interphase. In apparent contradiction, deficiency in each individual iCdk, respectively, in knockout mice proved to be compatible with live birth and in some instances fertility. Moreover, murine embryos could be derived with Cdk1 as the only functional Cdk. Thus, none of the iCdks is strictly essential for mammalian cell cycle progression, raising the possibility that Cdk1 is the dominant regulator in interphase. However, an absence of iCdks has been accompanied by major shifts in cyclin association to Cdk1, suggesting gain in function. After considerable tweaking, a chemical genetic approach has recently been able to examine the impact of acute inhibition of Cdk2 activity without marked distortion of cyclin/Cdk complex formation. The results suggest that, when expressed at its normal levels, Cdk2 performs essential roles in driving human cells into S phase and maintaining genomic stability. These new findings appear to have restored order to the cell cycle field, bringing it full circle to the view that iCdks indeed play important roles. They also underscore the caveat in knockdown and knockout approaches that protein underexpression can significantly perturb a protein interaction network. We discuss the implications of the new synthesis for future cell cycle studies and anti-Cdk-based therapy of cancer and other diseases.
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Abstract
The retinoblastoma protein gene RB-1 is mutated in one-third of human tumors. Its protein product, pRB (retinoblastoma protein), functions as a transcriptional coregulator in many fundamental cellular processes. Here, we report a nonnuclear role for pRB in apoptosis induction via pRB's direct participation in mitochondrial apoptosis. We uncovered this activity by finding that pRB potentiated TNFα-induced apoptosis even when translation was blocked. This proapoptotic function was highly BAX-dependent, suggesting a role in mitochondrial apoptosis, and accordingly, a fraction of endogenous pRB constitutively associated with mitochondria. Remarkably, we found that recombinant pRB was sufficient to trigger the BAX-dependent permeabilization of mitochondria or liposomes in vitro. Moreover, pRB interacted with BAX in vivo and could directly bind and conformationally activate BAX in vitro. Finally, by targeting pRB specifically to mitochondria, we generated a mutant that lacked pRB's classic nuclear roles. This mito-tagged pRB retained the ability to promote apoptosis in response to TNFα and also additional apoptotic stimuli. Most importantly, induced expression of mito-tagged pRB in Rb(-/-);p53(-/-) tumors was sufficient to block further tumor development. Together, these data establish a nontranscriptional role for pRB in direct activation of BAX and mitochondrial apoptosis in response to diverse stimuli, which is profoundly tumor-suppressive.
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Lamber EP, Beuron F, Morris EP, Svergun DI, Mittnacht S. Structural insights into the mechanism of phosphoregulation of the retinoblastoma protein. PLoS One 2013; 8:e58463. [PMID: 23516486 PMCID: PMC3597711 DOI: 10.1371/journal.pone.0058463] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2012] [Accepted: 02/05/2013] [Indexed: 01/20/2023] Open
Abstract
The retinoblastoma susceptibility protein RB1 is a key regulator of cell proliferation and fate. RB1 operates through nucleating the formation of multi-component protein complexes involved in the regulation of gene transcription, chromatin structure and protein stability. Phosphorylation of RB1 by cyclin-dependent kinases leads to conformational alterations and inactivates the capability of RB1 to bind partner protein. Using small angle X-ray scattering in combination with single particle analysis of transmission electron microscope images of negative-stained material we present the first three-dimensional reconstruction of non-phosphorylated RB1 revealing an extended architecture and deduce the domain arrangement within the molecule. Phosphorylation results in an overt alteration of the molecular shape and dimensions, consistent with the transition to a compact globular architecture. The work presented provides what is to our knowledge the first description of the relative domain arrangement in active RB1 and predicts the molecular movement that leads to RB1 inactivation following protein phosphorylation.
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Affiliation(s)
- Ekaterina P. Lamber
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - Fabienne Beuron
- Division of Structural Biology, Institute of Cancer Research, London, United Kingdom
| | - Edward P. Morris
- Division of Structural Biology, Institute of Cancer Research, London, United Kingdom
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Hamburg, Germany
| | - Sibylle Mittnacht
- Division of Cancer Biology, Institute of Cancer Research, London, United Kingdom
- Research Department of Cancer Biology, UCL Cancer Institute and National Institute for Health Research, University College London Hospitals Biomedical Research Centre, University College London, London, United Kingdom
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26
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Rosner M, Schipany K, Hengstschläger M. Merging high-quality biochemical fractionation with a refined flow cytometry approach to monitor nucleocytoplasmic protein expression throughout the unperturbed mammalian cell cycle. Nat Protoc 2013; 8:602-26. [DOI: 10.1038/nprot.2013.011] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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27
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Leukemogenesis as a new approach to investigate the correlation between up regulated gene 4/upregulator of cell proliferation (URG4/URGCP) and signal transduction genes in leukemia. Mol Biol Rep 2012; 40:3043-8. [DOI: 10.1007/s11033-012-2378-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 12/17/2012] [Indexed: 01/15/2023]
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28
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Vázquez-Iglesias L, Lostalé-Seijo I, Martínez-Costas J, Benavente J. Different intracellular distribution of avian reovirus core protein sigmaA in cells of avian and mammalian origin. Virology 2012; 432:495-504. [PMID: 22832119 DOI: 10.1016/j.virol.2012.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 06/19/2012] [Accepted: 07/05/2012] [Indexed: 11/26/2022]
Abstract
A comparative analysis of the intracellular distribution of avian reovirus (ARV) core protein sigmaA in cells of avian and mammalian origin revealed that, whereas the viral protein accumulates in the cytoplasm and nucleolus of avian cells, most sigmaA concentrates in the nucleoplasm of mammalian cells in tight association with the insoluble nuclear matrix fraction. Our results further showed that sigmaA becomes arrested in the nucleoplasm of mammalian cells via association with mammalian cell-specific factors and that this association prevents nucleolar targeting. Inhibition of RNA polymerase II activity, but not of RNA polymerase I activity, in infected mammalian cells induces nucleus-to-cytoplasm sigmaA translocation through a CRM1- and RanGTP-dependent mechanism, yet a heterokaryon assay suggests that sigmaA does not shuttle between the nucleus and cytoplasm. The scarcity of sigmaA in cytoplasmic viral factories of infected mammalian cells could be one of the factors contributing to limited ARV replication in mammalian cells.
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Affiliation(s)
- Lorena Vázquez-Iglesias
- Departamento de Bioquímica y Biología Molecular, y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain
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29
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Inactivation of Rb in stromal fibroblasts promotes epithelial cell invasion. EMBO J 2012; 31:3092-103. [PMID: 22643222 PMCID: PMC3400012 DOI: 10.1038/emboj.2012.153] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Accepted: 04/27/2012] [Indexed: 12/18/2022] Open
Abstract
Stromal-derived growth factors are required for normal epithelial growth but are also implicated in tumour progression. We have observed inactivation of the retinoblastoma protein (Rb), through phosphorylation, in cancer-associated fibroblasts in oro-pharyngeal cancer specimens. Rb is well known for its cell-autonomous effects on cancer initiation and progression; however, cell non-autonomous functions of Rb are not well described. We have identified a cell non-autonomous role of Rb, using three-dimensional cultures, where depletion of Rb in stromal fibroblasts enhances invasive potential of transformed epithelia. In part, this is mediated by upregulation of keratinocyte growth factor (KGF), which is produced by the depleted fibroblasts. KGF drives invasion of epithelial cells through induction of MMP1 expression in an AKT- and Ets2-dependent manner. Our data identify that stromal fibroblasts can alter the invasive behaviour of the epithelium, and we show that altered expression of KGF can mediate these functions.
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30
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Discrete phosphorylated retinoblastoma protein isoform expression in mouse tooth development. J Mol Histol 2012; 43:281-8. [PMID: 22476877 DOI: 10.1007/s10735-012-9404-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 03/11/2012] [Indexed: 12/27/2022]
Abstract
Retinoblastoma protein (pRb) phosphorylation plays a central role in mediating cell cycle G1/S stage transition, together with E2F transcription factors. The binding of pRb to E2F is thought to be controlled by the sequential and cumulative phosphorylation of pRb at various amino acids. In addition to well characterized roles as a tumor suppressor, pRb has more recently been implicated in osteoprogenitor and other types of stem cell maintenance, proliferation and differentiation, thereby influencing the morphogenesis of developing organs. In this study, we present data characterizing the expression of pRb and three phosphorylated pRb (ppRb) isoforms-ppRbS780, ppRbS795, ppRbS807/811-in developmentally staged mouse molar and incisor teeth. Our results reveal distinct developmental expression patterns for individual ppRb isoforms in dental epithelial and dental mesenchymal cell differentiation, suggesting discrete functions in tooth development.
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31
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The impact of CDK inhibition in human malignancies associated with pronounced defects in apoptosis: advantages of multi-targeting small molecules. Future Med Chem 2012; 4:395-424. [DOI: 10.4155/fmc.12.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Malignant cells in chronic lymphocytic leukemia (CLL) and related diseases are heterogeneous and consist primarily of long-lived resting cells in the periphery and a minor subset of dividing cells in proliferating centers. Both cell populations have different molecular signatures that play a major role in determining their sensitivity to therapy. Contemporary approaches to treating CLL are heavily reliant on cytotoxic chemotherapeutics. However, none of the current treatment regimens can be considered curative. Pharmacological CDK inhibitors have extended the repertoire of potential drugs for CLL. Multi-targeted CDK inhibitors affect CDKs involved in regulating both cell cycle progression and transcription. Their interference with transcriptional elongation represses anti-apoptotic proteins and, thus, promotes the induction of apoptosis. Importantly, there is evidence that treatment with CDK inhibitors can overcome resistance to therapy. The pharmacological CDK inhibitors have great potential for use in combination with other therapeutics and represent promising tools for the development of new curative treatments for CLL.
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Zheng Z, Li L, Liu X, Wang D, Tu B, Wang L, Wang H, Zhu W. 5‐Aza‐2'‐deoxycytidine reactivates gene expression
via
degradation of pRb pocket proteins. FASEB J 2011; 26:449-59. [DOI: 10.1096/fj.11-190025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Zhixing Zheng
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Lian Li
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Xiangyu Liu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Donglai Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Bo Tu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Lina Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Haiying Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
| | - Wei‐Guo Zhu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular BiologyPeking University Health Science Center, and Peking University‐Tsiinghua University Joint Center for Life Sciences, Peking University Beijing China
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The cell cycle regulator phosphorylated retinoblastoma protein is associated with tau pathology in several tauopathies. J Neuropathol Exp Neurol 2011; 70:578-87. [PMID: 21666500 DOI: 10.1097/nen.0b013e3182204414] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Retinoblastoma protein (pRb) is a ubiquitous 928-amino acid cell cycle regulatory molecule with diverse biologic activities. One critical function of pRb is the control of the G1-to-S phase checkpoint of the cell cycle. In the hypophosphorylated state, pRb suppresses the activity of E2F transcription factors thereby inhibiting transcription of cell cycle-promoting genes. On phosphorylation, primarily by cyclin-dependent kinases, phosphorylated pRb dissociates from E2F and permits cell cycle progression. We previously found phosphorylated pRb to be intimately associated with hyperphosphorylated tau-containing neurofibrillary tangles of Alzheimer disease (AD), the pathogenesis of which is believed to involve dysregulation of the cell cycle and marked neuronal death. Here, we used immunohistochemistry to investigate the presence of phosphorylated pRb in other distinct neurodegenerative diseases that share the common characteristic of hyperphosphorylated tau pathology and neuronal loss with AD.We found colocalized labeling of tau pathology and phosphorylated pRb in Pick disease and progressive supranuclear palsy (3 cases each), neurodegeneration with brain iron accumulation type 1 (2 cases), and Parkinson-amyotrophic lateral sclerosis of Guam, subacute sclerosing panencephalitis, frontotemporal dementia and Parkinsonism linked to chromosome 17, and dementia pugilistica (1 case each). These observations further implicate aberrant neuronal cell cycle progression in neurodegenerative diseases, particularly tauopathies, and suggest a novel target for therapeutic intervention.
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34
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Harrison MK, Adon AM, Saavedra HI. The G1 phase Cdks regulate the centrosome cycle and mediate oncogene-dependent centrosome amplification. Cell Div 2011; 6:2. [PMID: 21272329 PMCID: PMC3038874 DOI: 10.1186/1747-1028-6-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 01/27/2011] [Indexed: 11/10/2022] Open
Abstract
Because centrosome amplification generates aneuploidy and since centrosome amplification is ubiquitous in human tumors, a strong case is made for centrosome amplification being a major force in tumor biogenesis. Various evidence showing that oncogenes and altered tumor suppressors lead to centrosome amplification and aneuploidy suggests that oncogenes and altered tumor suppressors are a major source of genomic instability in tumors, and that they generate those abnormal processes to initiate and sustain tumorigenesis. We discuss how altered tumor suppressors and oncogenes utilize the cell cycle regulatory machinery to signal centrosome amplification and aneuploidy.
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Affiliation(s)
- Mary K Harrison
- Emory University, Department of Radiation Oncology, Winship Cancer Institute, 1701 Uppergate Drive, Atlanta, Georgia, 30322, USA.
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35
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Küppers M, Ittrich C, Faust D, Dietrich C. The transcriptional programme of contact-inhibition. J Cell Biochem 2010; 110:1234-43. [PMID: 20564218 DOI: 10.1002/jcb.22638] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Proliferation of non-transformed cells is regulated by cell-cell contacts, which are referred to as contact-inhibition. Vice versa, transformed cells are characterised by a loss of contact-inhibition. Despite its generally accepted importance for cell-cycle control, little is known about the intracellular signalling pathways involved in contact-inhibition. Unravelling the molecular mechanisms of contact-inhibition and its loss during tumourigenesis will be an important step towards the identification of novel target genes in tumour diagnosis and treatment. To better understand the underlying molecular mechanisms we identified the transcriptional programme of contact-inhibition in NIH3T3 fibroblast using high-density microarrays. Setting the cut off: >or=1.5-fold, P <or= 0.05, 853 genes and 73 cDNA sequences were differentially expressed in confluent compared to exponentially growing cultures. Importing these data into GenMAPP software revealed a comprehensive list of cell-cycle regulatory genes mediating G0/G1 arrest, which was confirmed by RT-PCR and Western blot. In a narrow analysis (cut off: >or=2-fold, P <or= 0.002), we found 110 transcripts to be differentially expressed representing 107 genes and 3 cDNA sequences involved, for example, in proliferation, signal transduction, transcriptional regulation, cell adhesion and communication. Interestingly, the majority of genes was upregulated indicating that contact-inhibition is not a passive state, but actively induced. Furthermore, we confirmed differential expression of eight genes by semi-quantitative RT-PCR and identified the potential tumour suppressor transforming growth factor-beta (TGF-beta)-1-induced clone 22 (TSC-22; tgfb1i4) as a novel protein to be induced in contact-inhibited cells.
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Affiliation(s)
- Monika Küppers
- Institute of Toxicology, Medical Center of the Johannes Gutenberg-University, Obere Zahlbacherstr 67, 55131 Mainz, Germany
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36
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Olson BJ, Oberholzer M, Li Y, Zones JM, Kohli HS, Bisova K, Fang SC, Meisenhelder J, Hunter T, Umen JG. Regulation of the Chlamydomonas cell cycle by a stable, chromatin-associated retinoblastoma tumor suppressor complex. THE PLANT CELL 2010; 22:3331-47. [PMID: 20978220 PMCID: PMC2990127 DOI: 10.1105/tpc.110.076067] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 08/31/2010] [Accepted: 10/09/2010] [Indexed: 05/19/2023]
Abstract
We examined the cell cycle dynamics of the retinoblastoma (RB) protein complex in the unicellular alga Chlamydomonas reinhardtii that has single homologs for each subunit-RB, E2F, and DP. We found that Chlamydomonas RB (encoded by MAT3) is a cell cycle-regulated phosphoprotein, that E2F1-DP1 can bind to a consensus E2F site, and that all three proteins interact in vivo to form a complex that can be quantitatively immunopurified. Yeast two-hybrid assays revealed the formation of a ternary complex between MAT3, DP1, and E2F1 that requires a C-terminal motif in E2F1 analogous to the RB binding domain of plant and animal E2Fs. We examined the abundance of MAT3/RB and E2F1-DP1 in highly synchronous cultures and found that they are synthesized and remain stably associated throughout the cell cycle with no detectable fraction of free E2F1-DP1. Consistent with their stable association, MAT3/RB and DP1 are constitutively nuclear, and MAT3/RB does not require DP1-E2F1 for nuclear localization. In the nucleus, MAT3/RB remains bound to chromatin throughout the cell cycle, and its chromatin binding is mediated through E2F1-DP1. Together, our data show that E2F-DP complexes can regulate the cell cycle without dissociation of their RB-related subunit and that other changes may be sufficient to convert RB-E2F-DP from a cell cycle repressor to an activator.
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Affiliation(s)
- Bradley J.S.C. Olson
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Michael Oberholzer
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Yubing Li
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James M. Zones
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Harjivan S. Kohli
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Katerina Bisova
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Su-Chiung Fang
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Jill Meisenhelder
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - Tony Hunter
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
| | - James G. Umen
- Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
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37
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Abstract
One of the many debated topics in ageing research is whether progeroid syndromes are really accelerated forms of human ageing. The answer requires a better understanding of the normal ageing process and the molecular pathology underlying these rare diseases. Exciting recent findings regarding a severe human progeria, Hutchinson-Gilford progeria syndrome, have implicated molecular changes that are also linked to normal ageing, such as genome instability, telomere attrition, premature senescence and defective stem cell homeostasis in disease development. These observations, coupled with genetic studies of longevity, lead to a hypothesis whereby progeria syndromes accelerate a subset of the pathological changes that together drive the normal ageing process.
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38
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Abstract
The retinoblastoma tumor suppressor gene (RB-1) is a key regulator of cellular senescence. Expression of the retinoblastoma protein (pRB) in human tumor cells that lack it results in senescence-like changes. The induction of the senescent phenotype by pRB requires the postmitotic kinase CDK5, the best known function of which is in neuronal development and postmitotic neuronal activities. Activation of CDK5 in neurons depends on its activators p35 and p39; however, little is known about how CDK5 is activated in non-neuronal senescent cells. Here we report that p35 is required for the activation of CDK5 in the process of cellular senescence. We demonstrate that: (i) p35 is expressed in osteosarcoma cells, (ii) p35 is required for CDK5 activation induced by pRB during senescence, (iii) p35 is required for the senescent morphological changes in which CDK5 is known to be involved as well as for expression of the senescence secretome, and (iv) p35 is up-regulated in senescing cells. Taken together, these results suggest that p35 is at least one of the activators of CDK5 that is mobilized in the process of cellular senescence, which may provide insight into cancer cell proliferation and future cancer therapeutics.
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Affiliation(s)
- Daqin Mao
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111, USA
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39
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Arcangeletti MC, Rodighiero I, De Conto F, Gatti R, Orlandini G, Ferraglia F, Motta F, Covan S, Razin SV, Dettori G, Chezzi C. Modulatory effect of rRNA synthesis and ppUL83 nucleolar compartmentalization on human cytomegalovirus gene expression in vitro. J Cell Biochem 2009; 108:415-23. [PMID: 19585527 PMCID: PMC7167110 DOI: 10.1002/jcb.22268] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The nucleolus is a nuclear domain involved in the biogenesis of ribosomes, as well as in many other important cellular regulatory activities, such as cell cycle control and mRNA processing. Many viruses, including herpesviruses, are known to exploit the nucleolar compartment during their replication cycle. In a previous study, we demonstrated the preferential targeting and accumulation of the human cytomegalovirus (HCMV) UL83 phosphoprotein (pp65) to the nucleolar compartment and, in particular, to the nucleolar matrix of lytically infected fibroblasts; such targeting was already evident at very early times after infection. Here we have investigated the possible effects of rRNA synthesis inhibition upon the development of HCMV lytic infection, by using either actinomycin D or cisplatin at low concentrations, that are known to selectively inhibit RNA polymerase I activity, whilst leaving RNA polymerase II function unaffected. Following the inhibition of rRNA synthesis by either of the agents used, we observed a significant redistribution of nucleolar proteins within the nucleoplasm and a simultaneous depletion of viral pp65 from the nucleolus; this effect was highly evident in both unextracted cells and in nuclear matrices in situ. Of particular interest, even a brief suppression of rRNA synthesis resulted in a very strong inhibition of the progression of HCMV infection, as was concluded from the absence of accumulation of HCMV major immediate‐early proteins within the nucleus of infected cells. These data suggest that a functional relationship might exist between rRNA synthesis, pp65 localization to the nucleolar matrix and the normal development of HCMV lytic infection. J. Cell. Biochem. 108: 415–423, 2009. © 2009 Wiley‐Liss, Inc.
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40
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Huart AS, MacLaine NJ, Meek DW, Hupp TR. CK1alpha plays a central role in mediating MDM2 control of p53 and E2F-1 protein stability. J Biol Chem 2009; 284:32384-94. [PMID: 19759023 DOI: 10.1074/jbc.m109.052647] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The ubiquitin ligase murine double minute clone 2 (MDM2) mediates ubiquitination and degradation of the tumor suppressor p53. The activation and stabilization of p53 by contrast is maintained by enzymes catalyzing p53 phosphorylation and acetylation. Casein kinase 1 (CK1) is one such enzyme; it stimulates p53 after transforming growth factor-beta treatment, irradiation, or DNA virus infection. We analyzed whether CK1 regulates p53 protein stability in unstressed conditions. Depletion of CK1 using small interfering RNA or inhibition of CK1 using the kinase inhibitor (D4476) activated p53 and destabilized E2F-1, indicating that steady-state levels of these proteins are controlled by CK1. Co-immunoprecipitation of endogenous CK1 with MDM2 occurred in undamaged cells, indicating the existence of a stable multiprotein complex, and as such, we evaluated whether the MDM2 Nutlin had similar pharmacological properties to the CK1 inhibitor D4476. Indeed, D4476 or Nutlin treatments resulted in the same p53 and E2F-1 steady-state protein level changes, indicating that the MDM2 x CK1 complex is both a negative regulator of p53 and a positive regulator of E2F-1 in undamaged cells. Although the treatment of cells with D4476 resulted in a partial p53-dependent growth arrest, the induction of p53-independent apoptosis by D4476 suggested a critical role for the MDM2 x CK1 complex in maintaining E2F-1 anti-apoptotic signaling. These data highlighting a pharmacological similarity between MDM2 and CK1 small molecule inhibitors and the fact that CK1 and MDM2 form a stable complex suggest that the MDM2 x CK1 complex is a component of a genetic pathway that co-regulates the stability of the p53 and E2F-1 transcription factors.
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Affiliation(s)
- Anne-Sophie Huart
- Cancer Research UK p53 Signal Transduction Group, University of Edinburgh, Institute of Genetics and Molecular Medicine, Division of Cancer Biology, Crewe Road South, Edinburgh EH4 2XR, Scotland, United Kingdom
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41
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Kandert S, Wehnert M, Müller CR, Buendia B, Dabauvalle MC. Impaired nuclear functions lead to increased senescence and inefficient differentiation in human myoblasts with a dominant p.R545C mutation in the LMNA gene. Eur J Cell Biol 2009; 88:593-608. [PMID: 19589617 DOI: 10.1016/j.ejcb.2009.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 06/05/2009] [Accepted: 06/05/2009] [Indexed: 11/26/2022] Open
Abstract
We have studied myoblasts from a patient with a severe autosomal dominant Emery-Dreifuss muscular dystrophy (AD-EDMD) caused by an arginine 545 to cystein point mutation (p.R545C) in the carboxy-terminal domain of the lamin A/C gene. This mutation has pleiotropic cellular effects on these myoblasts as demonstrated by nuclear structural defects, exhibiting lobulations which increase with cell passages in culture. The organization of both lamin A/C and its inner nuclear membrane partner emerin are altered, eventually showing a honeycomb pattern upon immunofluorescence microscopy. In addition, the distribution of histone H3 trimethylated at lysine 27 and of phosphorylated RNA polymerase II, markers of inactive and active chromatin domains, respectively, are altered suggesting an impact on gene expression. Patient myoblasts also presented a high index of senescence in ex vivo culture. Moreover, our data show for the first time in an AD-EDMD context that the 20S core particle of the proteasome was inactivated. With cell passages, the 20S core protein progressively accumulated into discrete nuclear foci that largely colocalized with promyelocytic leukemia (PML) bodies while p21 accumulated throughout the nuclear compartment. Proteasome inactivation has been linked to normal cellular ageing. Our data indicate that it may also contribute to premature senescence in AD-EDMD patient myoblasts. Finally, when transferred to low-serum medium, patient myoblasts were deficient in ex vivo differentiation, as assessed by the absence of myotube formation and myogenin induction. Altogether, these data suggest that the LMNA mutation p.R545C impairs both proliferation and differentiation capacities of myoblasts as part of the pathogenesis of AD-EDMD.
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Affiliation(s)
- Sebastian Kandert
- Division of Electron Microscopy, Biocenter, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Abstract
The nuclear matrix has remained a contentious structure for decades; many believe that it is an artefact of harsh non-physiological procedures. However, its visualization using milder experimental techniques is leading to its general acceptance by the scientific community. It is a permanent network of core filaments underlying thicker fibres which is proposed to be a platform for numerous important nuclear activities such as transcription and DNA repair. Interestingly, A- and B-type lamin proteins and emerin are components of this nuclear structure; however, they are often referred to only as nuclear envelope proteins. The present mini-review intends to provide an overview of the nuclear matrix, mentioning both its constituents and functional significance. The impact of disease-causing mutations in both emerin and lamin proteins on the structure's ability to regulate and mediate nuclear processes is then discussed.
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Gorges LL, Lents NH, Baldassare JJ. The extreme COOH terminus of the retinoblastoma tumor suppressor protein pRb is required for phosphorylation on Thr-373 and activation of E2F. Am J Physiol Cell Physiol 2008; 295:C1151-60. [PMID: 18768921 DOI: 10.1152/ajpcell.00300.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The retinoblastoma protein pRb plays a pivotal role in G(1)- to S-phase cell cycle progression and is among the most frequently mutated gene products in human cancer. Although much focus has been placed on understanding how the A/B pocket and COOH-terminal domain of pRb cooperate to relieve transcriptional repression of E2F-responsive genes, comparatively little emphasis has been placed on the function of the NH(2)-terminal region of pRb and the interaction of the multiple domains of pRb in the full-length context. Using "reverse mutational analysis" of Rb(DeltaCDK) (a dominantly active repressive allele of Rb), we have previously shown that restoration of Thr-373 is sufficient to render Rb(DeltaCDK) sensitive to inactivation via cyclin-CDK phosphorylation. This suggests that the NH(2)-terminal region plays a more critical role in pRb regulation than previously thought. In the present study, we have expanded this analysis to include additional residues in the NH(2)-terminal region of pRb and further establish that the mechanism of pRb inactivation by Thr-373 phosphorylation is through the dissociation of E2F. Most surprisingly, we further have found that removal of the COOH-terminal domain of either RbDeltaCDK(+T373) or wild-type pRb yields a functional allele that cannot be inactivated by phosphorylation and is repressive of E2F activation and S-phase entry. Our data demonstrate a novel function for the NH(2)-terminal domain of pRb and the necessity for cooperation of multiple domains for proper pRb regulation.
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Affiliation(s)
- Laura L Gorges
- Dept. of Pharmacological Sciences at Saint Louis Univ., St. Louis, MO 63104, USA
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UEDA M, AHMED N, BITO T, NAGANO T, ICHIHASHI M. The expression of retinoblastoma protein in epidermis is induced by ultraviolet B exposure. Br J Dermatol 2008. [DOI: 10.1046/j.1365-2133.1996.d01-1013.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Jiao W, Lin HM, Datta J, Braunschweig T, Chung JY, Hewitt SM, Rane SG. Aberrant nucleocytoplasmic localization of the retinoblastoma tumor suppressor protein in human cancer correlates with moderate/poor tumor differentiation. Oncogene 2008; 27:3156-64. [PMID: 18071317 DOI: 10.1038/sj.onc.1210970] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 10/24/2007] [Accepted: 11/01/2007] [Indexed: 12/21/2022]
Abstract
Inactivation of the retinoblastoma (RB) tumor suppressor pathway, via elevated cyclin-dependent kinase (CDK) activity, is observed in majority of human cancers. Since CDK deregulation is evident in most cancer cells, pharmacological CDK inhibition has become an attractive therapeutic strategy in oncology. We recently showed that an oncogenic CDK4(R24C) mutation alters the subcellular localization of the normally nuclear RB phosphoprotein. Here, using 71 human cancer cell lines and over 300 primary human cancer tissues, we investigated whether changes in RB subcellular localization occur during human cancer progression. We uncover that diverse human cancers and their derived cell lines, particularly those with poor tumor differentiation, display significant cytoplasmic mislocalization of ordinarily nuclear RB. The nucleocytoplasmically distributed RB was derived via CDK-dependent and Exportin1-mediated nuclear export. Indeed, cytoplasmically mislocalized RB could be efficiently confined to the nucleus by pharmacologically reducing CDK activity or by inhibiting the Exportin1-mediated nuclear export pathway. Our observations uncover a post-translational CDK-dependent mechanism of RB inactivation and suggest that cytoplasmically localized RB may harbor a tumor promoting function. We propose that RB inactivation, via aberrant nucleocytoplasmic transport, may disrupt normal cell differentiation programs and accelerate the cancer process. These results are evidence that tumor cells modulate the protein transport machinery thereby making the protein transport process a viable therapeutic target.
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Affiliation(s)
- W Jiao
- Laboratory of Cell Regulation and Carcinogenesis, Bethesda, MD, USA
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46
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Abstract
It is widely accepted that adenoviral E1A exerts its influence on recipient cells through binding to the retinoblastoma (Rb) family proteins, followed by a global release of E2F factors from pocket-protein control. Our study challenges this simple paradigm by demonstrating previously unappreciated complexity. We show that E1A-expressing primary and transformed cells are characterized by the persistence of Rb-E2F1 complexes. We provide evidence that E1A causes Rb stabilization by interfering with its proteasomal degradation. Functional experiments supported by biochemical data reveal not only a dramatic increase in Rb and E2F1 protein levels in E1A-expressing cells but also demonstrate their activation throughout the cell cycle. We further show that E1A activates an Rb- and E2F1-dependent S-phase checkpoint that attenuates the growth of cells that became hyperploid through errors in mitosis and supports the fidelity DNA replication even in the absence of E2F complexes with other Rb family proteins, thereby functionally substituting for the loss of p53. Our results support the essential role of Rb and E2F1 in the regulation of genomic stability and DNA damage checkpoints.
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Favreau C, Delbarre E, Courvalin JC, Buendia B. Differentiation of C2C12 myoblasts expressing lamin A mutated at a site responsible for Emery-Dreifuss muscular dystrophy is improved by inhibition of the MEK-ERK pathway and stimulation of the PI3-kinase pathway. Exp Cell Res 2008; 314:1392-405. [PMID: 18294630 DOI: 10.1016/j.yexcr.2008.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 01/15/2008] [Accepted: 01/25/2008] [Indexed: 12/29/2022]
Abstract
Mutation R453W in A-type lamins, that are major nuclear envelope proteins, generates Emery-Dreifuss muscular dystrophy. We previously showed that mouse myoblasts expressing R453W-lamin A incompletely exit the cell cycle and differentiate into myocytes with a low level of multinucleation. Here we attempted to improve differentiation by treating these cells with a mixture of PD98059, an extracellular-regulated kinase (ERK) kinase (also known as mitogen-activated kinase, MEK) inhibitor, and insulin-like growth factor-II, an activator of phosphoinositide 3-kinase. We show that mouse myoblasts expressing R453W-lamin A were sensitive to the drug treatment as shown by (i) an increase in multinucleation, (ii) downregulation of proliferation markers (cyclin D1, hyperphosphorylated Rb), (iii) upregulation of myogenin, and (iv) sustained activation of p21 and cyclin D3. However, nuclear matrix anchorage of p21 and cyclin D3 in a complex with hypophosphorylated Rb that is critical to trigger cell cycle arrest and myogenin induction was deficient and incompletely restored by drug treatment. As the turn-over of R453W-lamin A at the nuclear envelope was greatly enhanced, we propose that R453W-lamin A impairs the capacity of the nuclear lamina to serve as scaffold for substrates of the MEK-ERK pathway and for MyoD-induced proteins that play a role in the differentiation process.
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Affiliation(s)
- Catherine Favreau
- Institut Jacques Monod, UMR7592, CNRS et Universités Paris 6 et 7, Paris Cedex 05, France
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Mammoto A, Sero JE, Mammoto T, Ingber DE. Methods for studying mechanical control of angiogenesis by the cytoskeleton and extracellular matrix. Methods Enzymol 2008; 443:227-59. [PMID: 18772019 DOI: 10.1016/s0076-6879(08)02012-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mechanical forces that capillary endothelial cells generate in their cytoskeleton and exert on their extracellular matrix adhesions feed back to modulate cell sensitivity to soluble angiogenic factors, and thereby control vascular development. Here we describe various genetic, biochemical, and engineering methods that can be used to study, manipulate, and probe this physical mechanism of developmental control. These techniques are useful as in vitro angiogenesis models and for analyzing the molecular and biophysical basis of vascular control.
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Affiliation(s)
- Akiko Mammoto
- Vascular Biology Program, Department of Pathology, Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Wang Z, Xie Y, Zhang L, Zhang H, An X, Wang T, Meng A. Migratory Localization of Cyclin D2-Cdk4 Complex Suggests a Spatial Regulation of the G1-S Transition. Cell Struct Funct 2008; 33:171-83. [DOI: 10.1247/csf.08019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Zizhang Wang
- Research Center for Molecular and Developmental Biology, Institute of Botany, Chinese Academy of Sciences
- Department of Biological Sciences and Biotechnology, Tsinghua University
| | - Yongli Xie
- Department of Biological Sciences and Biotechnology, Tsinghua University
| | - Lixia Zhang
- Department of Biological Sciences and Biotechnology, Tsinghua University
| | - Haiwen Zhang
- Department of Biological Sciences and Biotechnology, Tsinghua University
| | - Xiaojing An
- Research Center for Molecular and Developmental Biology, Institute of Botany, Chinese Academy of Sciences
| | - Tai Wang
- Research Center for Molecular and Developmental Biology, Institute of Botany, Chinese Academy of Sciences
| | - Anming Meng
- Department of Biological Sciences and Biotechnology, Tsinghua University
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50
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De Santa F, Albini S, Mezzaroma E, Baron L, Felsani A, Caruso M. pRb-dependent cyclin D3 protein stabilization is required for myogenic differentiation. Mol Cell Biol 2007; 27:7248-65. [PMID: 17709384 PMCID: PMC2168908 DOI: 10.1128/mcb.02199-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The expression of retinoblastoma (pRb) and cyclin D3 proteins is highly induced during the process of skeletal myoblast differentiation. We have previously shown that cyclin D3 is nearly totally associated with hypophosphorylated pRb in differentiated myotubes, whereas Rb-/- myocytes fail to accumulate the cyclin D3 protein despite normal induction of cyclin D3 mRNA. Here we report that pRb promotes cyclin D3 protein accumulation in differentiating myoblasts by preventing cyclin D3 degradation. We show that cyclin D3 displays rapid turnover in proliferating myoblasts, which is positively regulated through glycogen synthase kinase 3beta (GSK-3beta)-mediated phosphorylation of cyclin D3 on Thr-283. We describe a novel interaction between pRb and cyclin D3 that maps to the C terminus of pRb and to a region of cyclin D3 proximal to the Thr-283 residue and provide evidence that the pRb-cyclin D3 complex formation in terminally differentiated myotubes hinders the access of GSK-3beta to cyclin D3, thus inhibiting Thr-283 phosphorylation. Interestingly, we observed that the ectopic expression of a stabilized cyclin D3 mutant in C2 myoblasts enhances muscle-specific gene expression; conversely, cyclin D3-null embryonic fibroblasts display impaired MyoD-induced myogenic differentiation. These results indicate that the pRb-dependent accumulation of cyclin D3 is functionally relevant to the process of skeletal muscle cell differentiation.
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Affiliation(s)
- Francesca De Santa
- CNR-Istituto di Neurobiologia e Medicina Molecolare, Fondazione S. Lucia, Via Fosso di Fiorano, 64-00143 Roma, Italy
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