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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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2
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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: 1] [Impact Index Per Article: 0.5] [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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3
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Conteduca G, Cangelosi D, Coco S, Malacarne M, Baldo C, Arado A, Pinto R, Testa B, Coviello DA. NSD1 Mutations in Sotos Syndrome Induce Differential Expression of Long Noncoding RNAs, miR646 and Genes Controlling the G2/M Checkpoint. Life (Basel) 2022; 12:life12070988. [PMID: 35888078 PMCID: PMC9324496 DOI: 10.3390/life12070988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/28/2022] [Accepted: 07/01/2022] [Indexed: 12/16/2022] Open
Abstract
An increasing amount of evidence indicates the critical role of the NSD1 gene in Sotos syndrome (SoS), a rare genetic disease, and in tumors. Molecular mechanisms affected by NSD1 mutations are largely uncharacterized. In order to assess the impact of NSD1 haploinsufficiency in the pathogenesis of SoS, we analyzed the gene expression profile of fibroblasts isolated from the skin samples of 15 SoS patients and of 5 healthy parents. We identified seven differentially expressed genes and five differentially expressed noncoding RNAs. The most upregulated mRNA was stratifin (SFN) (fold change, 3.9, Benjamini−Hochberg corrected p < 0.05), and the most downregulated mRNA was goosecoid homeobox (GSC) (fold change, 3.9, Benjamini−Hochberg corrected p < 0.05). The most upregulated lncRNA was lnc-C2orf84-1 (fold change, 4.28, Benjamini−Hochberg corrected p < 0.001), and the most downregulated lncRNA was Inc-C15orf57 (fold change, −0.7, Benjamini−Hochberg corrected p < 0.05). A gene set enrichment analysis reported the enrichment of genes involved in the KRAS and E2F signaling pathways, splicing regulation and cell cycle G2/M checkpoints. Our results suggest that NSD1 is involved in cell cycle regulation and that its mutation can induce the down-expression of genes involved in tumoral and neoplastic differentiation. The results contribute to defining the role of NSD1 in fibroblasts for the prevention, diagnosis and control of SoS.
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Affiliation(s)
- Giuseppina Conteduca
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Davide Cangelosi
- Clinical Bioinformatics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy;
| | - Simona Coco
- Lung Cancer Unit, IRCCS Ospedale Policlinico San Martino, 16132 Genoa, Italy;
| | - Michela Malacarne
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Chiara Baldo
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Alessia Arado
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Rute Pinto
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Barbara Testa
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
| | - Domenico A. Coviello
- Laboratory of Human Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (G.C.); (M.M.); (C.B.); (A.A.); (R.P.); (B.T.)
- Correspondence: ; Tel.: +39-010-5636-3977
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4
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Chen X, Litzenburger UM, Wei Y, Schep AN, LaGory EL, Choudhry H, Giaccia AJ, Greenleaf WJ, Chang HY. Joint single-cell DNA accessibility and protein epitope profiling reveals environmental regulation of epigenomic heterogeneity. Nat Commun 2018; 9:4590. [PMID: 30389926 PMCID: PMC6214962 DOI: 10.1038/s41467-018-07115-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/10/2018] [Indexed: 11/09/2022] Open
Abstract
Here we introduce Protein-indexed Assay of Transposase Accessible Chromatin with sequencing (Pi-ATAC) that combines single-cell chromatin and proteomic profiling. In conjunction with DNA transposition, the levels of multiple cell surface or intracellular protein epitopes are recorded by index flow cytometry and positions in arrayed microwells, and then subject to molecular barcoding for subsequent pooled analysis. Pi-ATAC simultaneously identifies the epigenomic and proteomic heterogeneity in individual cells. Pi-ATAC reveals a casual link between transcription factor abundance and DNA motif access, and deconvolute cell types and states in the tumor microenvironment in vivo. We identify a dominant role for hypoxia, marked by HIF1α protein, in the tumor microvenvironment for shaping the regulome in a subset of epithelial tumor cells.
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Affiliation(s)
- Xingqi Chen
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.,Department of Cell and Molecular Biology, Karolinska Institutet, 17177, Solna, Sweden
| | - Ulrike M Litzenburger
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.
| | - Yuning Wei
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA
| | - Alicia N Schep
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.,Dept of Genetics, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Edward L LaGory
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, CA, 94305, USA
| | - Hani Choudhry
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah 22252, Saudi Arabia
| | - Amato J Giaccia
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, CA, 94305, USA
| | - William J Greenleaf
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA.,Dept of Genetics, Stanford University, Stanford, CA, 94305, USA.,Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, 94305, USA. .,Howard Hughes Medical Institute, Stanford University, Stanford, CA, 94305, USA.
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5
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Konishi Y, Tominaga A. PU.1 is degraded in differentiation of erythrocytes through a proteasome-dependent pathway. DNA Cell Biol 2006; 25:340-5. [PMID: 16792504 DOI: 10.1089/dna.2006.25.340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The transcription factor PU.1 regulates erythrocyte differentiation. We previously reported that F5-5 erythroblasts differentiate into erythrocytes in response to activin by degrading PU.1, and that inhibiting PU.1- degradation suppresses F5-5 cell differentiation into erythrocytes. These findings suggest that regulating PU.1 degradation is critical for terminal differentiation of erythrocytes. Here, we investigate the mechanism underlying PU.1 degradation during successive differentiation of erythrocytes. Using 2D-MS proteomic analysis, we show that proteasome subunits and proteins required for degradation by proteasomes immunoprecipitate with PU.1 in response to activin. Furthermore, a proteasome inhibitor, lactacystin, partially suppresses differentiation of F5-5 cells into erythrocytes in response to activin, and partially inhibits PU.1 degradation. Our results indicate that degradation of PU.1 necessary for erythrocyte differentiation occurs, in part, through the proteasome pathway.
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Affiliation(s)
- Yuko Konishi
- Medical Research Center, Kochi Medical School, Kochi University, Kochi, Japan.
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Suzuki M, Yamada T, Kihara-Negishi F, Sakurai T, Hara E, Tenen DG, Hozumi N, Oikawa T. Site-specific DNA methylation by a complex of PU.1 and Dnmt3a/b. Oncogene 2006; 25:2477-88. [PMID: 16331260 DOI: 10.1038/sj.onc.1209272] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 10/06/2005] [Accepted: 10/20/2005] [Indexed: 11/09/2022]
Abstract
The Ets transcription factor PU.1 is a hematopoietic master regulator essential for the development of myeloid and B-cell lineages. As we previously reported, PU.1 sometimes represses transcription on forming a complex with mSin3A-histone deacetyl transferase-MeCP2. Here, we show an interaction between PU.1 and DNA methyltransferases, DNA methyltransferase (Dnmt)3a and Dnmt3b (Dnmt3s). Glutathione-S-transferase pulldown assay revealed that PU.1 directly interacted with the ATRX domain of Dnmt3s through the ETS domain. Dnmt3s repressed the transcriptional activity of PU.1 on a reporter construct with trimerized PU.1-binding sites. The repression was recovered by addition of 5-aza-deoxycitidine, a DNA methyltransferase inhibitor, but not trichostatin A, a histone deacetylase inhibitor. Bisulfite sequence analysis revealed that several CpG sites in the promoter region neighboring the PU.1-binding sites were methylated when Dnmt3s were coexpressed with PU.1. We also showed that the CpG sites in the p16(INK4A) promoter were methylated by overexpression of PU.1 in NIH3T3 cells, accompanied by a downregulation of p16(INK4A) gene expression. These results suggest that PU.1 may downregulate its target genes through an epigenetic modification such as DNA methylation.
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Affiliation(s)
- M Suzuki
- Department of Cell Genetics, Sasaki Institute, Tokyo, Japan
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7
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Geng CD, Vedeckis WV. c-Myb and members of the c-Ets family of transcription factors act as molecular switches to mediate opposite steroid regulation of the human glucocorticoid receptor 1A promoter. J Biol Chem 2005; 280:43264-71. [PMID: 16263717 DOI: 10.1074/jbc.m508245200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Steroid auto-regulation of the human glucocorticoid receptor (hGR) 1A promoter in lymphoblast cells resides largely in two DNA elements (footprints 11 and 12). We show here that c-Myb and c-Ets family members (Ets-1/2, PU.1, and Spi-B) control hGR 1A promoter regulation in T- and B-lymphoblast cells. Two T-lymphoblast lines, CEM-C7 and Jurkat, contain high levels of c-Myb and low levels of PU.1, whereas the opposite is true in IM-9 B-lymphoblasts. In Jurkat cells, overexpression of c-Ets-1, c-Ets-2, or PU.1 effectively represses dexamethasone-mediated up-regulation of an hGR 1A promoter-luciferase reporter gene, as do dominant negative c-Myb (c-Myb DNA-binding domain) or Ets proteins (Ets-2 DNA-binding domain). Overexpression of c-Myb in IM-9 cells confers hormone-dependent up-regulation to the hGR 1A promoter reporter gene. Chromatin immunoprecipitation assays show that hormone treatment causes the recruitment of hGR and c-Myb to the hGR 1A promoter in CEM-C7 cells, whereas hGR and PU.1 are recruited to this promoter in IM-9 cells. These observations suggest that the specific transcription factor that binds to footprint 12, when hGR binds to the adjacent footprint 11, determines the direction of hGR 1A promoter auto-regulation. This leads to a "molecular switch" model for auto-regulation of the hGR 1A promoter.
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Affiliation(s)
- Chuan-dong Geng
- Department of Biochemistry and Molecular Biology and Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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8
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Rekhtman N, Choe KS, Matushansky I, Murray S, Stopka T, Skoultchi AI. PU.1 and pRB interact and cooperate to repress GATA-1 and block erythroid differentiation. Mol Cell Biol 2003; 23:7460-74. [PMID: 14559995 PMCID: PMC207581 DOI: 10.1128/mcb.23.21.7460-7474.2003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PU.1 and GATA-1 are two hematopoietic specific transcription factors that play key roles in development of the myeloid and erythroid lineages, respectively. The two proteins bind to one another and inhibit each other's function in transcriptional activation and promotion of their respective differentiation programs. This mutual antagonism may be an important aspect of lineage commitment decisions. PU.1 can also act as an oncoprotein since deregulated expression of PU.1 in erythroid precursors causes erythroleukemias in mice. Studies of cultured mouse erythroleukemia cell lines indicate that one aspect of PU.1 function in erythroleukemogenesis is its ability to block erythroid differentiation by repressing GATA-1 (N. Rekhtman, F. Radparvar, T. Evans, and A. I. Skoultchi, Genes Dev. 13:1398-1411, 1999). We have investigated the mechanism of PU.1-mediated repression of GATA-1. We report here that PU.1 binds to GATA-1 on DNA. We localized the repression activity of PU.1 to a small acidic N-terminal domain that interacts with the C pocket of pRB, a well-known transcriptional corepressor. Repression of GATA-1 by PU.1 requires pRB, and pRB colocalizes with PU.1 and GATA-1 at repressed GATA-1 target genes. PU.1 and pRB also cooperate to block erythroid differentiation. Our results suggest that one of the mechanisms by which PU.1 antagonizes GATA-1 is by binding to it at GATA-1 target genes and tethering to these sites a corepressor that blocks transcriptional activity and thereby erythroid differentiation.
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Affiliation(s)
- Natasha Rekhtman
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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9
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Ishii H, Sen R, Pazin MJ. Combinatorial control of DNase I-hypersensitive site formation and erasure by immunoglobulin heavy chain enhancer-binding proteins. J Biol Chem 2003; 279:7331-8. [PMID: 14660676 DOI: 10.1074/jbc.m308973200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNase I-hypersensitive sites in cellular chromatin are usually believed to be nucleosome-free regions generated by transcription factor binding. Using a cell-free system we show that hypersensitivity does not simply correlate with the number of DNA-bound proteins. Specifically, the leucine zipper containing basic helix-loop-helix protein TFE3 was sufficient to induce a DNase I-hypersensitive site at the immunoglobulin heavy chain micro enhancer in vitro. TFE3 enhanced binding of an ETS protein PU.1 to the enhancer. However, PU.1 binding erased the DNase I-hypersensitive site without abolishing TFE3 binding. Furthermore, TFE3 binding enhanced transcription in the presence and absence of a hypersensitive site, whereas endonuclease accessibility correlated strictly with DNase I hypersensitivity. We infer that chromatin constraints for transcription and nuclease sensitivity can differ.
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Affiliation(s)
- Haruhiko Ishii
- Graduate Program in Biophysics and Structural Biology, Brandeis University, Waltham, Massachusetts 02454, USA
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10
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Suzuki M, Yamada T, Kihara-Negishi F, Sakurai T, Oikawa T. Direct association between PU.1 and MeCP2 that recruits mSin3A-HDAC complex for PU.1-mediated transcriptional repression. Oncogene 2003; 22:8688-98. [PMID: 14647463 DOI: 10.1038/sj.onc.1207182] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PU.1, a member of the Ets family of transcription factors, is implicated in hematopoietic cell differentiation through its interactions with other transcriptional factors and cofactors. To identify a novel protein(s) binding to PU.1, we carried out affinity purification using a column of Glutathione-Sepharose beads bound to GST-PU.1 fusion protein and isolated several individual proteins using murine erythroleukemia (MEL) cell extracts. Sequence analysis of these proteins revealed that one was MeCP2 a methyl CpG binding protein. GST-pull-down assay and immunoprecipitation assay showed that PU.1 bound directly to MeCP2 via its Ets domain and MeCP2 bound to PU.1 via either its amino terminal domain or trans-repression domain. MeCP2 repressed transcriptional activity of PU.1 on a reporter construct with trimerized PU.1 binding sites. This downregulation was recovered in the presence of histone deacetylase inhibitor, trichostatin A (TSA). MeCP2 was integrated in PU.1-mSin3A-HDAC complex but not in PU.1-CBP complex. Chromatin immunoprecipitation (ChIP) assays showed that PU.1 and MeCP2 were collocated at the PU.1 binding site on the reporter construct and the PU.1 binding site of the intervening sequence 2 (IVS2) region in the intron of the beta-globin gene, which has been proposed to regulate expression of the gene, in undifferentiated MEL cells. The complex disappeared from the region during the course of erythroid differentiation of MEL cells. Our results suggest that MeCP2 acts as a corepressor of PU.1 probably due to facilitating complex formation with mSin3A and HDACs.
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Affiliation(s)
- Mitsuhiro Suzuki
- Department of Cell Genetics, Sasaki Institute, 2-2 Kanda Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan
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11
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Whyatt D, Grosveld F. Cell-nonautonomous function of the retinoblastoma tumour suppressor protein: new interpretations of old phenotypes. EMBO Rep 2002; 3:130-5. [PMID: 11839697 PMCID: PMC1083974 DOI: 10.1093/embo-reports/kvf033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Loss of the retinoblastoma protein (pRb) induces a cell-nonautonomous defect in both erythroid and neuronal differentiation. It has previously been thought that this reflects a requirement for pRb function in cells that normally support erythropoiesis and neurogenesis, rather than in the erythrocytes or neurons themselves. However, recent studies have challenged this interpretation, and it appears that erythrocytes and neurons themselves have the intrinsic requirement for pRb function. This requirement can be bypassed by signals supplied by wild-type erythroid or neuronal cells. The existence of such a signalling mechanism has implications not only in understanding pRb function but also in the interpretation of other cell-nonautonomous phenotypes.
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Affiliation(s)
- David Whyatt
- Erasmus University, Department of Cell Biology and Genetics, Medical Genetics Centre, PO Box 1738, 3000 DR Rotterdam, The Netherlands
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12
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Abstract
Studies of the retinoblastoma gene (Rb) have shown that its protein product (pRb) acts to restrict cell proliferation, inhibit apoptosis, and promote cell differentiation. The frequent mutation of the Rb gene, and the functional inactivation of pRb in tumor cells, have spurred interest in the mechanism of pRb action. Recently, much attention has focused on pRb's role in the regulation of the E2F transcription factor. However, biochemical studies have suggested that E2F is only one of many pRb-targets and, to date, at least 110 cellular proteins have been reported to associate with pRb. The plethora of pRb-binding proteins raises several important questions. How many functions does pRb possess, which of these functions are important for development, and which contribute to tumor suppression? The goal of this review is to summarize the current literature of pRb-associated proteins.
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Affiliation(s)
- E J Morris
- Laboratory of Molecular Oncology, Massachusetts General Hospital Cancer Center, Charlestown, Massachusetts 02129, USA
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Wakahara M, Yamaguchi M. Erythropoiesis and Conversion of RBCs and Hemoglobins from Larval to Adult Type during Amphibian Development. Zoolog Sci 2001. [DOI: 10.2108/zsj.18.891] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Watanabe Y, Hashizume M, Kataoka S, Hamaguchi E, Morimoto N, Tsuru S, Katoh S, Miyake K, Matsushima K, Tominaga M, Kurashige T, Fujimoto S, Kincade PW, Tominaga A. Differentiation stages of eosinophils characterized by hyaluronic acid binding via CD44 and responsiveness to stimuli. DNA Cell Biol 2001; 20:189-202. [PMID: 11403716 DOI: 10.1089/104454901750219071] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To characterize interleukin (IL)-5-induced eosinophils, we examined the expression of CD44, very late antigen (VLA)-4, and the IL-5 receptor alpha chain, as well as the levels of eosinophil peroxidase and the generation of superoxide. Eosinophils were prepared from IL-5-transgenic mice, then characterized using electron microscopy to determine their responses to stimuli. Whereas CD44 densities remained almost constant, the level of VLA-4 increased in parallel with eosinophil maturation. Although a subset of IL-5-induced eosinophils with high side scatter recovered from bone marrow and rare ones found in blood recognized hyaluronic acid (HA), most did not have this property. Bone marrow eosinophils with high side scatter and lower density contained eosinophil peroxidase, not only in granules, but also in membranous structures for 30% of this population. This population developed HA-binding ability in response to IL-3, IL-4, IL-5, granulocyte-macrophage colony-stimulating factor, macrophage inflammatory protein (MIP)-2, monocyte chemotactic protein (MCP)-1, eotaxin, nerve growth factor (NGF), and opsonized zymosan (OZ). Peripheral blood eosinophils acquired HA-binding ability in response to the same stimuli, but their responses were less than those of bone marrow eosinophils with high levels of side scatter. However, splenic eosinophils did not respond to these stimuli. Although peripheral blood eosinophils did not proliferate when stimulated by IL-5, these were the only cells that released eosinophil peroxidase in response to IL-4, MIP-2, MCP-1, eotaxin, NGF, and OZ. With the exception of a subset of bone marrow eosinophils, the ability to acquire HA binding, but not the ability to generate superoxide, correlated with eosinophil peroxidase activity and major basic protein accumulation in the granules of maturing cells.
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Affiliation(s)
- Y Watanabe
- Department of Medical Biology, Kochi Medical School, Nankoku City, Kochi, Japan
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Remy P, Baltzinger M. The Ets-transcription factor family in embryonic development: lessons from the amphibian and bird. Oncogene 2000; 19:6417-31. [PMID: 11175358 DOI: 10.1038/sj.onc.1204044] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This chapter reviews the expression and role of Ets-genes during embryogenesis of amphibians and birds. In addition to overlapping expression domains, some of them exhibit cell type-specific expression. Many of them are expressed in migratory cells: neural crest, endothelial, and pronephric duct cells for instance. They are also transcribed in embryonic areas affected by epithelio-mesenchymal transitions. Both processes involve modifications of cellular adhesion. Ets-family genes appear to coordinate changes in the expression of adhesion molecules and degradation of the extracellular matrix upon regulation of matrix metalloproteinases and their specific inhibitors. These functions are essential for physiological processes like tissue remodelling during embryogenesis or wound healing. Unfortunately they also play a harmful role in metastasis. Recent studies in the nervous system showed that Ets-genes contribute to the establishment of a cellular identity. This identity could rely on definite cell-surface determinants, among which cadherins could play an important role. In addition to cell-type specific expression, other factors contribute to the specificity of function of Ets-genes. These genes have a broad specificity of recognition of target sequences in gene promoters, insufficient for accurate control of gene expression. A fine tuning could arise from combinatorial interactions with other Ets- or accessory proteins.
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Affiliation(s)
- P Remy
- FRE 2168 du CNRS, IPCB, 21 rue René Descartes, 67084 Strasbourg cedex, France
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16
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Abstract
Ets proteins are a family of transcription factors that share an 85 amino acid conserved DNA binding domain, the ETS domain. Over 25 mammalian Ets family members control important biological processes, including cellular proliferation, differentiation, lymphocyte development and activation, transformation and apoptosis by recognizing the GGA core motif in the promoter or enhancer of their target genes. Protein - protein interactions regulates DNA binding, subcellular localization, target gene selection and transcriptional activity of Ets proteins. Combinatorial control is a characteristic property of Ets family members, involving interaction between Ets and other key transcriptional factors such as AP-1, NFkappaB and Pax family members. Specific domains of Ets proteins interact with many protein motifs such as bHLH, bZipper and Paired domain. Such interactions coordinate cellular processes in response to diverse signals including cytokines, growth factors, antigen and cellular stresses.
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Affiliation(s)
- R Li
- Center for Molecular and Structural Biology, Medical University of South Carolina, Charleston, South Carolina, SC 29425, USA
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17
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Sawada K, Konishi Y, Tominaga M, Watanabe Y, Hirano J, Inoue S, Kageyama R, Blum M, Tominaga A. Goosecoid suppresses cell growth and enhances neuronal differentiation of PC12 cells. J Cell Sci 2000; 113 ( Pt 15):2705-13. [PMID: 10893186 DOI: 10.1242/jcs.113.15.2705] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In all vertebrate species, the homeobox gene goosecoid serves as a marker of the Spemann organizer tissue. One function of the organizer is the induction of neural tissue. To investigate the role of goosecoid in neuronal differentiation of mammalian cells, we have introduced goosecoid into PC12 cells. Expression of goosecoid resulted in reduced cell proliferation and enhanced neurite outgrowth in response to NGF. Expression of goosecoid led to a decrease in the percentage of S-phase cells and to upregulation of the expression of the neuron-specific markers MAP-1b and neurofilament-L. Analysis of goosecoid mutants revealed that these effects were independent of either DNA binding or homodimerization of Goosecoid. Coexpression of the N-terminal portion of the ets transcription factor PU.1, a protein that can bind to Goosecoid, repressed neurite outgrowth and rescued the proliferation of PC12 cultures. In contrast, expression of the bHLH transcription factor HES-1 repressed goosecoid-mediated neurite outgrowth without changing the proportion of S-phase cells. These results suggest that goosecoid is involved in neuronal differentiation in two ways, by slowing the cell cycle and stimulating neurite outgrowth, and that these two events are separately regulated.
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Affiliation(s)
- K Sawada
- Department of Neuropsychiatry, Kochi Medical School, Kohasu, Okoh-cho, Nankoku City, Kochi 783-8505, Japan
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