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Yu G, Chen Y, Hu Y, Zhou Y, Ding X, Zhou X. Roles of transducin-like enhancer of split (TLE) family proteins in tumorigenesis and immune regulation. Front Cell Dev Biol 2022; 10:1010639. [PMID: 36438567 PMCID: PMC9692235 DOI: 10.3389/fcell.2022.1010639] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/31/2022] [Indexed: 08/16/2023] Open
Abstract
Mammalian transducin-like enhancer of split family proteins (TLEs) are homologous to Drosophila Groucho (Gro) and are essential transcriptional repressors. Seven TLE family members, TLE1-7, have been identified to date. These proteins do not bind DNA directly; instead, they bind a set of transcription factors and thereby inhibit target gene expression. Loss of TLEs in mice usually leads to defective early development; however, TLE functions in developmentally mature cells are unclear. Recent studies have revealed that TLEs are dysregulated in certain human cancer types and may function as oncogenes or tumor suppressors in different contexts. TLE levels also affect the efficacy of cancer treatments and the development of drug resistance. In addition, TLEs play critical roles in the development and function of immune cells, including macrophages and lymphocytes. In this review, we provide updates on the expression, function, and mechanism of TLEs; discuss the roles played by TLEs in tumorigenesis and the inflammatory response; and elaborate on several TLE-associated signaling pathways, including the Notch, Wnt, and MAPK pathways. Finally, we discuss potential strategies for targeting TLEs in cancer therapy.
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Affiliation(s)
- Guiping Yu
- Department of Immunology, Nantong University, School of Medicine, Nantong, China
- Department of Cardiothoracic Surgery, The Affiliated Jiangyin Hospital of Nantong University, Jiangyin, China
| | - Yiqi Chen
- Department of Immunology, Nantong University, School of Medicine, Nantong, China
| | - Yuwen Hu
- Department of Immunology, Nantong University, School of Medicine, Nantong, China
| | - Yan Zhou
- Department of Periodontology, The Affiliated Nantong Stomatological Hospital of Nantong University, Nantong, China
| | - Xiaoling Ding
- Department of Gastroenterology, The Affiliated Hospital of Nantong University, Nantong, China
| | - Xiaorong Zhou
- Department of Immunology, Nantong University, School of Medicine, Nantong, China
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2
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Shirakawa T, Toyono T, Inoue A, Matsubara T, Kawamoto T, Kokabu S. Factors Regulating or Regulated by Myogenic Regulatory Factors in Skeletal Muscle Stem Cells. Cells 2022; 11:cells11091493. [PMID: 35563799 PMCID: PMC9104119 DOI: 10.3390/cells11091493] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 11/23/2022] Open
Abstract
MyoD, Myf5, myogenin, and MRF4 (also known as Myf6 or herculin) are myogenic regulatory factors (MRFs). MRFs are regarded as master transcription factors that are upregulated during myogenesis and influence stem cells to differentiate into myogenic lineage cells. In this review, we summarize MRFs, their regulatory factors, such as TLE3, NF-κB, and MRF target genes, including non-myogenic genes such as taste receptors. Understanding the function of MRFs and the physiology or pathology of satellite cells will contribute to the development of cell therapy and drug discovery for muscle-related diseases.
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Affiliation(s)
- Tomohiko Shirakawa
- Division of Orofacial Functions and Orthodontics, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan; (T.S.); (A.I.); (T.K.)
- Division of Molecular Signaling and Biochemistry, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan;
| | - Takashi Toyono
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan;
| | - Asako Inoue
- Division of Orofacial Functions and Orthodontics, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan; (T.S.); (A.I.); (T.K.)
- Division of Molecular Signaling and Biochemistry, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan;
| | - Takuma Matsubara
- Division of Molecular Signaling and Biochemistry, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan;
| | - Tatsuo Kawamoto
- Division of Orofacial Functions and Orthodontics, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan; (T.S.); (A.I.); (T.K.)
| | - Shoichiro Kokabu
- Division of Molecular Signaling and Biochemistry, Department of Health Improvement, Kyushu Dental University, Kitakyushu 803-8580, Japan;
- Correspondence: ; Tel.: +81-93-582-1131; Fax: +81-93-285-6000
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Anthony CC, Robbins DJ, Ahmed Y, Lee E. Nuclear Regulation of Wnt/β-Catenin Signaling: It's a Complex Situation. Genes (Basel) 2020; 11:genes11080886. [PMID: 32759724 PMCID: PMC7465203 DOI: 10.3390/genes11080886] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 12/26/2022] Open
Abstract
Wnt signaling is an evolutionarily conserved metazoan cell communication pathway required for proper animal development. Of the myriad of signaling events that have been ascribed to cellular activation by Wnt ligands, the canonical Wnt/β-catenin pathway has been the most studied and best understood. Misregulation of Wnt/β-catenin signaling has been implicated in developmental defects in the embryo and major diseases in the adult. Despite the latter, no drugs that inhibit the Wnt/β-catenin pathway have been approved by the FDA. In this review, we explore the least understood step in the Wnt/β-catenin pathway-nuclear regulation of Wnt target gene transcription. We initially describe our current understanding of the importation of β-catenin into the nucleus. We then focus on the mechanism of action of the major nuclear proteins implicated in driving gene transcription. Finally, we explore the concept of a nuclear Wnt enhanceosome and propose a modified model that describes the necessary components for the transcription of Wnt target genes.
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Affiliation(s)
- Christin C. Anthony
- Department of Cell & Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA;
| | - David J. Robbins
- Molecular Oncology Program, Division of Surgical Oncology, Dewitt Daughtry Family Department of Surgery, and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL 33136, USA;
| | - Yashi Ahmed
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA;
| | - Ethan Lee
- Department of Cell & Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA;
- Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Correspondence:
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Richard SA, Jia-Hao Z. Elucidating the pathogenic and biomarker potentials of FOXG1 in glioblastoma. Oncol Rev 2020; 14:444. [PMID: 32395201 PMCID: PMC7204822 DOI: 10.4081/oncol.2020.444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/20/2020] [Indexed: 12/11/2022] Open
Abstract
Glioblastoma (GB) is an extremely pugnacious brain cancer originating from neural stem (NS) cell-like cells. Forkhead box G1 (FOXG1; previously recognized as BF-1, qin, Chicken Brain Factor 1, or XBF-1 and renamed FOXG1 for mouse and human, and FoxG1 for other chordates) is an evolutionary preserved transcription factor driven from the forkhead box group of proteins FOXG1 modulates the speed of neurogenesis by maintaining progenitor cells in a proliferative mode as well as obstructing their differentiation into neurons during the initial periods of cortical formation. FOXG1 has been implicated in the formation of central nervous system (CNS) tumors and precisely GBs. Pathophysiologically, joint actions of FOXG1 and phosphatidylinositol- 3-kinases (PI3K) intermediate in intrinsic resistance of human GB cells to transforming growth factor-beta (TGF-β) stimulation of cyclin-dependent kinase inhibitor 1(p21Cip1) as well as growth inhibition. FOXG1 and NOTCH signaling pathways may functionally interrelate at different stages to facilitate gliomagenesis. Furthermore, FoxG1 actively contributed to the formation of transcription suppression complexes with corepressors of the Groucho/transducin-like Enhancer of split (Gro/TLEs). Also, FOXG1 was stimulated by Gro/TLE1 and abridged by Grg6. FOXG1 silencing in brain tumor-initiating cells (BTICs) also resulted in diminished secretion of markers characteristic undifferentiated natural neural stem/progenitor cells (NSPC) states, such as Oligodendrocyte transcription factor (OLIG2), (sex determining region Y)-box 2. (SOX2) and B lymphoma Mo-MLV insertion region 1 homolog (BMI1). This review therefore focuses on the pathogenic and biomarker potentials of FOXG1 in GB.
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Affiliation(s)
- Seidu A Richard
- Department of Neurosurgery, The Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu Province, P.R. China.,Department of Medicine, Princefield University, Ho-Volta Region, Ghana, West Africa
| | - Zhou Jia-Hao
- Department of Neurosurgery, The Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu Province, P.R. China
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Miller SW, Movsesyan A, Zhang S, Fernández R, Posakony JW. Evolutionary emergence of Hairless as a novel component of the Notch signaling pathway. eLife 2019; 8:48115. [PMID: 31545167 PMCID: PMC6777938 DOI: 10.7554/elife.48115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 09/23/2019] [Indexed: 11/30/2022] Open
Abstract
Suppressor of Hairless [Su(H)], the transcription factor at the end of the Notch pathway in Drosophila, utilizes the Hairless protein to recruit two co-repressors, Groucho (Gro) and C-terminal Binding Protein (CtBP), indirectly. Hairless is present only in the Pancrustacea, raising the question of how Su(H) in other protostomes gains repressive function. We show that Su(H) from a wide array of arthropods, molluscs, and annelids includes motifs that directly bind Gro and CtBP; thus, direct co-repressor recruitment is ancestral in the protostomes. How did Hairless come to replace this ancestral paradigm? Our discovery of a protein (S-CAP) in Myriapods and Chelicerates that contains a motif similar to the Su(H)-binding domain in Hairless has revealed a likely evolutionary connection between Hairless and Metastasis-associated (MTA) protein, a component of the NuRD complex. Sequence comparison and widely conserved microsynteny suggest that S-CAP and Hairless arose from a tandem duplication of an ancestral MTA gene.
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Affiliation(s)
- Steven W Miller
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States
| | - Artem Movsesyan
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States
| | - Sui Zhang
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States
| | - Rosa Fernández
- Bioinformatics and Genomics Unit, Center for Genomic Regulation, Barcelona, Spain
| | - James W Posakony
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States
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6
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Gammons M, Bienz M. Multiprotein complexes governing Wnt signal transduction. Curr Opin Cell Biol 2018; 51:42-49. [PMID: 29153704 DOI: 10.1016/j.ceb.2017.10.008] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/10/2017] [Indexed: 12/30/2022]
Abstract
Three multiprotein complexes have key roles in transducing Wnt signals from the plasma membrane to the cell nucleus - the β-catenin destruction complex, or Axin degradasome, which targets the Wnt effector β-catenin for proteasomal degradation in the absence of Wnt; the Wnt signalosome, assembled by polymerization of Dishevelled upon Wnt engaging its receptors, to inactivate the Axin degradasome, which allows β-catenin to accumulate; and the Wnt enhanceosome which enables β-catenin to gain access to target genes, to relieve their transcriptional repression by Groucho/TLE. This review focuses on recent advances that have highlighted mechanistic principles governing the assembly and function of these complexes.
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Affiliation(s)
- Melissa Gammons
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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7
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Ramakrishnan AB, Sinha A, Fan VB, Cadigan KM. The Wnt Transcriptional Switch: TLE Removal or Inactivation? Bioessays 2017; 40. [PMID: 29250807 DOI: 10.1002/bies.201700162] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/12/2017] [Indexed: 01/06/2023]
Abstract
Many targets of the Wnt/β-catenin signaling pathway are regulated by TCF transcription factors, which play important roles in animal development, stem cell biology, and oncogenesis. TCFs can regulate Wnt targets through a "transcriptional switch," repressing gene expression in unstimulated cells and promoting transcription upon Wnt signaling. However, it is not clear whether this switch mechanism is a general feature of Wnt gene regulation or limited to a subset of Wnt targets. Co-repressors of the TLE family are known to contribute to the repression of Wnt targets in the absence of signaling, but how they are inactivated or displaced by Wnt signaling is poorly understood. In this mini-review, we discuss several recent reports that address the prevalence and molecular mechanisms of the Wnt transcription switch, including the finding of Wnt-dependent ubiquitination/inactivation of TLEs. Together, these findings highlight the growing complexity of the regulation of gene expression by the Wnt pathway.
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Affiliation(s)
| | - Abhishek Sinha
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048
| | - Vinson B Fan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048
| | - Ken M Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048
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8
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Tortelote GG, Reis RR, de Almeida Mendes F, Abreu JG. Complexity of the Wnt/β‑catenin pathway: Searching for an activation model. Cell Signal 2017; 40:30-43. [PMID: 28844868 DOI: 10.1016/j.cellsig.2017.08.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/08/2017] [Accepted: 08/23/2017] [Indexed: 12/13/2022]
Abstract
Wnt signaling refers to a conserved signaling pathway, widely studied due to its roles in cellular communication, cell fate decisions, development and cancer. However, the exact mechanism underlying inhibition of the GSK phosphorylation towards β-catenin and activation of the pathway after biding of Wnt ligand to its cognate receptors at the plasma membrane remains unclear. Wnt target genes are widely spread over several animal phyla. They participate in a plethora of functions during the development of an organism, from axial specification, gastrulation and organogenesis all the way to regeneration and repair in adults. Temporal and spatial oncogenetic re-activation of Wnt signaling almost certainly leads to cancer. Wnt signaling components have been extensively studied as possible targets in anti-cancer therapies. In this review we will discuss one of the most intriguing questions in this field, that is how β-catenin, a major component in this pathway, escapes the destruction complex, gets stabilized in the cytosol and it is translocated to the nucleus where it acts as a co-transcription factor. Four major models have evolved during the past 20years. We dissected each of them along with current views and future perspectives on this pathway. This review will focus on the molecular mechanisms by which Wnt proteins modulate β-catenin cytoplasmic levels and the relevance of this pathway for the development and cancer.
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Affiliation(s)
- Giovane G Tortelote
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Renata R Reis
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabio de Almeida Mendes
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jose Garcia Abreu
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
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9
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Flack JE, Mieszczanek J, Novcic N, Bienz M. Wnt-Dependent Inactivation of the Groucho/TLE Co-repressor by the HECT E3 Ubiquitin Ligase Hyd/UBR5. Mol Cell 2017; 67:181-193.e5. [PMID: 28689657 PMCID: PMC5592244 DOI: 10.1016/j.molcel.2017.06.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 05/01/2017] [Accepted: 06/09/2017] [Indexed: 12/19/2022]
Abstract
Extracellular signals are transduced to the cell nucleus by effectors that bind to enhancer complexes to operate transcriptional switches. For example, the Wnt enhanceosome is a multiprotein complex associated with Wnt-responsive enhancers through T cell factors (TCF) and kept silent by Groucho/TLE co-repressors. Wnt-activated β-catenin binds to TCF to overcome this repression, but how it achieves this is unknown. Here, we discover that this process depends on the HECT E3 ubiquitin ligase Hyd/UBR5, which is required for Wnt signal responses in Drosophila and human cell lines downstream of activated Armadillo/β-catenin. We identify Groucho/TLE as a functionally relevant substrate, whose ubiquitylation by UBR5 is induced by Wnt signaling and conferred by β-catenin. Inactivation of TLE by UBR5-dependent ubiquitylation also involves VCP/p97, an AAA ATPase regulating the folding of various cellular substrates including ubiquitylated chromatin proteins. Thus, Groucho/TLE ubiquitylation by Hyd/UBR5 is a key prerequisite that enables Armadillo/β-catenin to activate transcription.
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Affiliation(s)
- Joshua E Flack
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Juliusz Mieszczanek
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Nikola Novcic
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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Kokabu S, Nakatomi C, Matsubara T, Ono Y, Addison WN, Lowery JW, Urata M, Hudnall AM, Hitomi S, Nakatomi M, Sato T, Osawa K, Yoda T, Rosen V, Jimi E. The transcriptional co-repressor TLE3 regulates myogenic differentiation by repressing the activity of the MyoD transcription factor. J Biol Chem 2017; 292:12885-12894. [PMID: 28607151 DOI: 10.1074/jbc.m116.774570] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/08/2017] [Indexed: 11/06/2022] Open
Abstract
Satellite cells are skeletal muscle stem cells that provide myonuclei for postnatal muscle growth, maintenance, and repair/regeneration in adults. Normally, satellite cells are mitotically quiescent, but they are activated in response to muscle injury, in which case they proliferate extensively and exhibit up-regulated expression of the transcription factor MyoD, a master regulator of myogenesis. MyoD forms a heterodimer with E proteins through their basic helix-loop-helix domain, binds to E boxes in the genome and thereby activates transcription at muscle-specific promoters. The central role of MyoD in muscle differentiation has increased interest in finding potential MyoD regulators. Here we identified transducin-like enhancer of split (TLE3), one of the Groucho/TLE family members, as a regulator of MyoD function during myogenesis. TLE3 was expressed in activated and proliferative satellite cells in which increased TLE3 levels suppressed myogenic differentiation, and, conversely, reduced TLE3 levels promoted myogenesis with a concomitant increase in proliferation. We found that, via its glutamine- and serine/proline-rich domains, TLE3 interferes with MyoD function by disrupting the association between the basic helix-loop-helix domain of MyoD and E proteins. Our findings indicate that TLE3 participates in skeletal muscle homeostasis by dampening satellite cell differentiation via repression of MyoD transcriptional activity.
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Affiliation(s)
- Shoichiro Kokabu
- Divisions of Molecular Signaling and Biochemistry, Kyushu Dental University, Kitakyushu 803-8580, Japan; Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan; Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts 02115.
| | - Chihiro Nakatomi
- Divisions of Molecular Signaling and Biochemistry, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Takuma Matsubara
- Divisions of Molecular Signaling and Biochemistry, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Yusuke Ono
- Musculoskeletal Molecular Biology Research Group, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8102, Japan
| | - William N Addison
- Research Unit, Department of Human Genetics, Shriners Hospitals for Children, McGill University, Montreal, Quebec H4A 0A9, Canada
| | - Jonathan W Lowery
- Division of Biomedical Science, College of Osteopathic Medicine, Marian University, Indianapolis, Indiana 46222
| | - Mariko Urata
- Divisions of Molecular Signaling and Biochemistry, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Aaron M Hudnall
- Division of Biomedical Science, College of Osteopathic Medicine, Marian University, Indianapolis, Indiana 46222
| | - Suzuro Hitomi
- Division of Physiology, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Mitsushiro Nakatomi
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Tsuyoshi Sato
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
| | - Kenji Osawa
- Division of Oral Medicine, Department of Science of Physical Functions, Kyushu Dental University, Kitakyushu 803-8580, Japan
| | - Tetsuya Yoda
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
| | - Vicki Rosen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts 02115
| | - Eijiro Jimi
- Divisions of Molecular Signaling and Biochemistry, Kyushu Dental University, Kitakyushu 803-8580, Japan; Oral Health Brain Health Total Health, Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
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11
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Chambers M, Turki-Judeh W, Kim MW, Chen K, Gallaher SD, Courey AJ. Mechanisms of Groucho-mediated repression revealed by genome-wide analysis of Groucho binding and activity. BMC Genomics 2017; 18:215. [PMID: 28245789 PMCID: PMC5331681 DOI: 10.1186/s12864-017-3589-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 02/13/2017] [Indexed: 12/24/2022] Open
Abstract
Background The transcriptional corepressor Groucho (Gro) is required for the function of many developmentally regulated DNA binding repressors, thus helping to define the gene expression profile of each cell during development. The ability of Gro to repress transcription at a distance together with its ability to oligomerize and bind to histones has led to the suggestion that Gro may spread along chromatin. However, much is unknown about the mechanism of Gro-mediated repression and about the dynamics of Gro targeting. Results Our chromatin immunoprecipitation sequencing analysis of temporally staged Drosophila embryos shows that Gro binds in a highly dynamic manner primarily to clusters of discrete (<1 kb) segments. Consistent with the idea that Gro may facilitate communication between silencers and promoters, Gro binding is enriched at both cis-regulatory modules, as well as within the promotors of potential target genes. While this Gro-recruitment is required for repression, our data show that it is not sufficient for repression. Integration of Gro binding data with transcriptomic analysis suggests that, contrary to what has been observed for another Gro family member, Drosophila Gro is probably a dedicated repressor. This analysis also allows us to define a set of high confidence Gro repression targets. Using publically available data regarding the physical and genetic interactions between these targets, we are able to place them in the regulatory network controlling development. Through analysis of chromatin associated pre-mRNA levels at these targets, we find that genes regulated by Gro in the embryo are enriched for characteristics of promoter proximal paused RNA polymerase II. Conclusions Our findings are inconsistent with a one-dimensional spreading model for long-range repression and suggest that Gro-mediated repression must be regulated at a post-recruitment step. They also show that Gro is likely a dedicated repressor that sits at a prominent highly interconnected regulatory hub in the developmental network. Furthermore, our findings suggest a role for RNA polymerase II pausing in Gro-mediated repression. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3589-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael Chambers
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Wiam Turki-Judeh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.,Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA
| | - Min Woo Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Kenny Chen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Sean D Gallaher
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.,Department of Energy, Institute of Genomics and Proteomics, University of California, Los Angeles, CA, 90095, USA
| | - Albert J Courey
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA. .,Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA.
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12
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Pflugfelder G, Eichinger F, Shen J. T-Box Genes in Drosophila Limb Development. Curr Top Dev Biol 2017; 122:313-354. [DOI: 10.1016/bs.ctdb.2016.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Cell Fate and Differentiation of Bone Marrow Mesenchymal Stem Cells. Stem Cells Int 2016; 2016:3753581. [PMID: 27298623 PMCID: PMC4889852 DOI: 10.1155/2016/3753581] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/05/2016] [Indexed: 01/18/2023] Open
Abstract
Osteoblasts and bone marrow adipocytes originate from bone marrow mesenchymal stem cells (BMMSCs) and there appears to be a reciprocal relationship between adipogenesis and osteoblastogenesis. Alterations in the balance between adipogenesis and osteoblastogenesis in BMMSCs wherein adipogenesis is increased relative to osteoblastogenesis are associated with decreased bone quality and quantity. Several proteins have been reported to regulate this reciprocal relationship but the exact nature of the signals regulating the balance between osteoblast and adipocyte formation within the bone marrow space remains to be determined. In this review, we focus on the role of Transducin-Like Enhancer of Split 3 (TLE3), which was recently reported to regulate the balance between osteoblast and adipocyte formation from BMMSCs. We also discuss evidence implicating canonical Wnt signalling, which plays important roles in both adipogenesis and osteoblastogenesis, in regulating TLE3 expression. Currently, there is demand for new effective therapies that target the stimulation of osteoblast differentiation to enhance bone formation. We speculate that reducing TLE3 expression or activity in BMMSCs could be a useful approach towards increasing osteoblast numbers and reducing adipogenesis in the bone marrow environment.
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Kwong PN, Chambers M, Vashisht AA, Turki-Judeh W, Yau TY, Wohlschlegel JA, Courey AJ. The Central Region of the Drosophila Co-repressor Groucho as a Regulatory Hub. J Biol Chem 2015; 290:30119-30. [PMID: 26483546 DOI: 10.1074/jbc.m115.681171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Indexed: 12/23/2022] Open
Abstract
Groucho (Gro) is a Drosophila co-repressor that regulates the expression of a large number of genes, many of which are involved in developmental control. Previous studies have shown that its central region is essential for function even though its three domains are poorly conserved and intrinsically disordered. Using these disordered domains as affinity reagents, we have now identified multiple embryonic Gro-interacting proteins. The interactors include protein complexes involved in chromosome organization, mRNA processing, and signaling. Further investigation of the interacting proteins using a reporter assay showed that many of them modulate Gro-mediated repression either positively or negatively. The positive regulators include components of the spliceosomal subcomplex U1 small nuclear ribonucleoprotein (U1 snRNP). A co-immunoprecipitation experiment confirms this finding and suggests that a sizable fraction of nuclear U1 snRNP is associated with Gro. The use of RNA-seq to analyze the gene expression profile of cells subjected to knockdown of Gro or snRNP-U1-C (a component of U1 snRNP) showed a significant overlap between genes regulated by these two factors. Furthermore, comparison of our RNA-seq data with Gro and RNA polymerase II ChIP data led to a number of insights, including the finding that Gro-repressed genes are enriched for promoter-proximal RNA polymerase II. We conclude that the Gro central domains mediate multiple interactions required for repression, thus functioning as a regulatory hub. Furthermore, interactions with the spliceosome may contribute to repression by Gro.
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Affiliation(s)
- Pak N Kwong
- From the Departments of Chemistry and Biochemistry and
| | | | | | - Wiam Turki-Judeh
- From the Departments of Chemistry and Biochemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Tak Yu Yau
- From the Departments of Chemistry and Biochemistry and
| | - James A Wohlschlegel
- Biological Chemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Albert J Courey
- From the Departments of Chemistry and Biochemistry and Molecular Biology Institute, UCLA, Los Angeles, California 90095
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15
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Ke J, Ma H, Gu X, Thelen A, Brunzelle JS, Li J, Xu HE, Melcher K. Structural basis for recognition of diverse transcriptional repressors by the TOPLESS family of corepressors. SCIENCE ADVANCES 2015; 1:e1500107. [PMID: 26601214 PMCID: PMC4646777 DOI: 10.1126/sciadv.1500107] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 06/04/2015] [Indexed: 05/18/2023]
Abstract
TOPLESS (TPL) and TOPLESS-related (TPR) proteins comprise a conserved family of plant transcriptional corepressors that are related to Tup1, Groucho, and TLE (transducin-like enhancer of split) corepressors in yeast, insects, and mammals. In plants, TPL/TPR corepressors regulate development, stress responses, and hormone signaling through interaction with small ethylene response factor-associated amphiphilic repression (EAR) motifs found in diverse transcriptional repressors. How EAR motifs can interact with TPL/TPR proteins is unknown. We confirm the amino-terminal domain of the TPL family of corepressors, which we term TOPLESS domain (TPD), as the EAR motif-binding domain. To understand the structural basis of this interaction, we determined the crystal structures of the TPD of rice (Os) TPR2 in apo (apo protein) state and in complexes with the EAR motifs from Arabidopsis NINJA (novel interactor of JAZ), IAA1 (auxin-responsive protein 1), and IAA10, key transcriptional repressors involved in jasmonate and auxin signaling. The OsTPR2 TPD adopts a new fold of nine helices, followed by a zinc finger, which are arranged into a disc-like tetramer. The EAR motifs in the three different complexes adopt a similar extended conformation with the hydrophobic residues fitting into the same surface groove of each OsTPR2 monomer. Sequence alignments and structure-based mutagenesis indicate that this mode of corepressor binding is highly conserved in a large set of transcriptional repressors, thus providing a general mechanism for gene repression mediated by the TPL family of corepressors.
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Affiliation(s)
- Jiyuan Ke
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, People’s Republic of China
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
| | - Honglei Ma
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, People’s Republic of China
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
| | - Xin Gu
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
| | - Adam Thelen
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
| | - Joseph S. Brunzelle
- Department of Molecular Pharmacology and Biological Chemistry, Life Sciences Collaborative Access Team, Synchrotron Research Center, Northwestern University, Argonne, IL 60439, USA
| | - Jiayang Li
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - H. Eric Xu
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, People’s Republic of China
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
- Corresponding author. E-mail: (H.E.X.); (K.M.)
| | - Karsten Melcher
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, People’s Republic of China
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, 333 Bostwick Avenue Northeast, Grand Rapids, MI 49503, USA
- Corresponding author. E-mail: (H.E.X.); (K.M.)
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16
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Kaul A, Schuster E, Jennings BH. The Groucho co-repressor is primarily recruited to local target sites in active chromatin to attenuate transcription. PLoS Genet 2014; 10:e1004595. [PMID: 25165826 PMCID: PMC4148212 DOI: 10.1371/journal.pgen.1004595] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 07/03/2014] [Indexed: 12/25/2022] Open
Abstract
Gene expression is regulated by the complex interaction between transcriptional activators and repressors, which function in part by recruiting histone-modifying enzymes to control accessibility of DNA to RNA polymerase. The evolutionarily conserved family of Groucho/Transducin-Like Enhancer of split (Gro/TLE) proteins act as co-repressors for numerous transcription factors. Gro/TLE proteins act in several key pathways during development (including Notch and Wnt signaling), and are implicated in the pathogenesis of several human cancers. Gro/TLE proteins form oligomers and it has been proposed that their ability to exert long-range repression on target genes involves oligomerization over broad regions of chromatin. However, analysis of an endogenous gro mutation in Drosophila revealed that oligomerization of Gro is not always obligatory for repression in vivo. We have used chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) to profile Gro recruitment in two Drosophila cell lines. We find that Gro predominantly binds at discrete peaks (<1 kilobase). We also demonstrate that blocking Gro oligomerization does not reduce peak width as would be expected if Gro oligomerization induced spreading along the chromatin from the site of recruitment. Gro recruitment is enriched in “active” chromatin containing developmentally regulated genes. However, Gro binding is associated with local regions containing hypoacetylated histones H3 and H4, which is indicative of chromatin that is not fully open for efficient transcription. We also find that peaks of Gro binding frequently overlap the transcription start sites of expressed genes that exhibit strong RNA polymerase pausing and that depletion of Gro leads to release of polymerase pausing and increased transcription at a bona fide target gene. Our results demonstrate that Gro is recruited to local sites by transcription factors to attenuate rather than silence gene expression by promoting histone deacetylation and polymerase pausing. Repression by transcription factors plays a central role in gene regulation. The Groucho/Transducin-Like Enhancer of split (Gro/TLE) family of co-repressors interacts with many different transcription factors and has many essential roles during animal development. Groucho/TLE proteins form oligomers that are necessary for target gene repression in some contexts. We have profiled the genome-wide recruitment of the founding member of this family, Groucho (from Drosophila) to gain insight into how and where it binds with respect to target genes and to identify factors associated with its binding. We find that Groucho binds in discrete peaks, frequently at transcription start sites, and that blocking Groucho from forming oligomers does not significantly change the pattern of Groucho recruitment. Although Groucho acts as a repressor, Groucho binding is enriched in chromatin that is permissive for transcription, and we find that it acts to attenuate rather than completely silence target gene expression. Thus, Groucho does not act as an “on/off” switch on target gene expression, but rather as a “mute” button.
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Affiliation(s)
- Aamna Kaul
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Eugene Schuster
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Barbara H. Jennings
- UCL Cancer Institute, University College London, London, United Kingdom
- * E-mail:
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17
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Chodaparambil JV, Pate KT, Hepler MRD, Tsai BP, Muthurajan UM, Luger K, Waterman ML, Weis WI. Molecular functions of the TLE tetramerization domain in Wnt target gene repression. EMBO J 2014; 33:719-31. [PMID: 24596249 DOI: 10.1002/embj.201387188] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Wnt signaling activates target genes by promoting association of the co-activator β-catenin with TCF/LEF transcription factors. In the absence of β-catenin, target genes are silenced by TCF-mediated recruitment of TLE/Groucho proteins, but the molecular basis for TLE/TCF-dependent repression is unclear. We describe the unusual three-dimensional structure of the N-terminal Q domain of TLE1 that mediates tetramerization and binds to TCFs. We find that differences in repression potential of TCF/LEFs correlates with their affinities for TLE-Q, rather than direct competition between β-catenin and TLE for TCFs as part of an activation-repression switch. Structure-based mutation of the TLE tetramer interface shows that dimers cannot mediate repression, even though they bind to TCFs with the same affinity as tetramers. Furthermore, the TLE Q tetramer, not the dimer, binds to chromatin, specifically to K20 methylated histone H4 tails, suggesting that the TCF/TLE tetramer complex promotes structural transitions of chromatin to mediate repression.
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Affiliation(s)
- Jayanth V Chodaparambil
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
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18
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GRG5/AES interacts with T-cell factor 4 (TCF4) and downregulates Wnt signaling in human cells and zebrafish embryos. PLoS One 2013; 8:e67694. [PMID: 23840876 PMCID: PMC3698143 DOI: 10.1371/journal.pone.0067694] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 05/22/2013] [Indexed: 12/27/2022] Open
Abstract
Transcriptional control by TCF/LEF proteins is crucial in key developmental processes such as embryo polarity, tissue architecture and cell fate determination. TCFs associate with β-catenin to activate transcription in the presence of Wnt signaling, but in its absence act as repressors together with Groucho-family proteins (GRGs). TCF4 is critical in vertebrate intestinal epithelium, where TCF4-β-catenin complexes are necessary for the maintenance of a proliferative compartment, and their abnormal formation initiates tumorigenesis. However, the extent of TCF4-GRG complexes' roles in development and the mechanisms by which they repress transcription are not completely understood. Here we characterize the interaction between TCF4 and GRG5/AES, a Groucho family member whose functional relationship with TCFs has been controversial. We map the core GRG interaction region in TCF4 to a 111-amino acid fragment and show that, in contrast to other GRGs, GRG5/AES-binding specifically depends on a 4-amino acid motif (LVPQ) present only in TCF3 and some TCF4 isoforms. We further demonstrate that GRG5/AES represses Wnt-mediated transcription both in human cells and zebrafish embryos. Importantly, we provide the first evidence of an inherent repressive function of GRG5/AES in dorsal-ventral patterning during early zebrafish embryogenesis. These results improve our understanding of TCF-GRG interactions, have significant implications for models of transcriptional repression by TCF-GRG complexes, and lay the groundwork for in depth direct assessment of the potential role of Groucho-family proteins in both normal and abnormal development.
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Kharazmi J, Moshfegh C. Investigation of dmyc Promoter and Regulatory Regions. GENE REGULATION AND SYSTEMS BIOLOGY 2013; 7:85-102. [PMID: 23761963 PMCID: PMC3663572 DOI: 10.4137/grsb.s10751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Products of the myc gene family integrate extracellular signals by modulating a wide range of their targets involved in cellular biogenesis and metabolism; the purpose of this integration is to regulate cell death, proliferation, and differentiation. However, understanding the regulation of myc at the transcription level remains a challenge. We performed rapid amplification of dmyc cDNA ends (5' RACE) and mapped the transcription start site at P1 promoter, 18 base pairs upstream of the start of the known EST GM01143 and within the 5' UTR. Our data show that the first TATA box, previously computationally predicted, is utilized to generate dmyc full length mRNA. The largest transcript contains all three exons, generated after the removal of the introns by constitutively regulated splicing events. Further investigation of Downstream Promoter Element (DPE) was achieved by studying lacZ reporter activity; investigation revealed that this element and its upstream cluster of binding sites are required for the dmyc intron 2 activity. These findings may provide valuable tools for further analysis of dmyc cis-elements.
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Affiliation(s)
- Jasmine Kharazmi
- Bio-Technopark Zurich, Molecular Biology Laboratory, Zurich, Switzerland. ; Institute of Molecular Life Sciences, University of Zurich-Irchel, Zurich, Switzerland
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20
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Establishment of motor neuron-V3 interneuron progenitor domain boundary in ventral spinal cord requires Groucho-mediated transcriptional corepression. PLoS One 2012; 7:e31176. [PMID: 22363571 PMCID: PMC3281934 DOI: 10.1371/journal.pone.0031176] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 01/03/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Dorsoventral patterning of the developing spinal cord is important for the correct generation of spinal neuronal types. This process relies in part on cross-repressive interactions between specific transcription factors whose expression is regulated by Sonic hedgehog. Groucho/transducin-like Enhancer of split (TLE) proteins are transcriptional corepressors suggested to be recruited by at least certain Sonic hedgehog-controlled transcription factors to mediate the formation of spatially distinct progenitor domains within the ventral spinal cord. The aim of this study was to characterize the involvement of TLE in mechanisms regulating the establishment of the boundary between the most ventral spinal cord progenitor domains, termed pMN and p3. Because the pMN domain gives rise to somatic motor neurons while the p3 domain generates V3 interneurons, we also examined the involvement of TLE in the acquisition of these neuronal fates. METHODOLOGY AND PRINCIPAL FINDINGS A combination of in vivo loss- and gain-of-function studies in the developing chick spinal cord was performed to characterize the role of TLE in ventral progenitor domain formation. It is shown here that TLE overexpression causes increased numbers of p3 progenitors and promotes the V3 interneuron fate while suppressing the motor neuron fate. Conversely, dominant-inhibition of TLE increases the numbers of pMN progenitors and postmitotic motor neurons. CONCLUSION Based on these results, we propose that TLE is important to promote the formation of the p3 domain and subsequent generation of V3 interneurons.
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21
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Turki-Judeh W, Courey AJ. The unconserved groucho central region is essential for viability and modulates target gene specificity. PLoS One 2012; 7:e30610. [PMID: 22319573 PMCID: PMC3272004 DOI: 10.1371/journal.pone.0030610] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/26/2011] [Indexed: 12/31/2022] Open
Abstract
Groucho (Gro) is a Drosophila corepressor required by numerous DNA-binding repressors, many of which are distributed in gradients and provide positional information during development. Gro contains well-conserved domains at its N- and C-termini, and a poorly conserved central region that includes the GP, CcN, and SP domains. All lethal point mutations in gro map to the conserved regions, leading to speculation that the unconserved central domains are dispensable. However, our sequence analysis suggests that the central domains are disordered leading us to suspect that the lack of lethal mutations in this region reflects a lack of order rather than an absence of essential functions. In support of this conclusion, genomic rescue experiments with Gro deletion variants demonstrate that the GP and CcN domains are required for viability. Misexpression assays using these same deletion variants show that the SP domain prevents unrestrained and promiscuous repression by Gro, while the GP and CcN domains are indispensable for repression. Deletion of the GP domain leads to loss of nuclear import, while deletion of the CcN domain leads to complete loss of repression. Changes in Gro activity levels reset the threshold concentrations at which graded repressors silence target gene expression. We conclude that co-regulators such as Gro are not simply permissive components of the repression machinery, but cooperate with graded DNA-binding factors in setting borders of gene expression. We suspect that disorder in the Gro central domains may provide the flexibility that allows this region to mediate multiple interactions required for repression.
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Affiliation(s)
- Wiam Turki-Judeh
- Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Albert J. Courey
- Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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22
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Kharazmi J, Moshfegh C, Brody T. Identification of cis-Regulatory Elements in the dmyc Gene of Drosophila Melanogaster. GENE REGULATION AND SYSTEMS BIOLOGY 2012; 6:15-42. [PMID: 22267917 PMCID: PMC3256997 DOI: 10.4137/grsb.s8044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Myc is a crucial regulator of growth and proliferation during animal development. Many signals and transcription factors lead to changes in the expression levels of Drosophila myc, yet no clear model exists to explain the complexity of its regulation at the level of transcription. In this study we used Drosophila genetic tools to track the dmyc cis-regulatory elements. Bioinformatics analyses identified conserved sequence blocks in the noncoding regions of the dmyc gene. Investigation of lacZ reporter activity driven by upstream, downstream, and intronic sequences of the dmyc gene in embryonic, larval imaginal discs, larval brain, and adult ovaries, revealed that it is likely to be transcribed from multiple transcription initiation units including a far upstream regulatory region, a TATA box containing proximal complex and a TATA-less downstream promoter element in conjunction with an initiator within the intron 2 region. Our data provide evidence for a modular organization of dmyc regulatory sequences; these modules will most likely be required to generate the tissue-specific patterns of dmyc transcripts. The far upstream region is active in late embryogenesis, while activity of other cis elements is evident during embryogenesis, in specific larval imaginal tissues and during oogenesis. These data provide a framework for further investigation of the transcriptional regulatory mechanisms of dmyc.
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Affiliation(s)
- Jasmine Kharazmi
- Biotechnopark Zurich, Molecular Biology Laboratory, University of Zurich-Irchel, Zurich, Switzerland
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Abstract
Wnts are conserved, secreted signaling proteins that can influence cell behavior by stabilizing β-catenin. Accumulated β-catenin enters the nucleus, where it physically associates with T-cell factor (TCF) family members to regulate target gene expression in many developmental and adult tissues. Recruitment of β-catenin to Wnt response element (WRE) chromatin converts TCFs from transcriptional repressors to activators. This review will outline the complex interplay between factors contributing to TCF repression and coactivators working with β-catenin to regulate Wnt targets. In addition, three variations of the standard transcriptional switch model will be discussed. One is the Wnt/β-catenin symmetry pathway in Caenorhabditis elegans, where Wnt-mediated nuclear efflux of TCF is crucial for activation of targets. Another occurs in vertebrates, where distinct TCF family members are associated with repression and activation, and recent evidence suggests that Wnt signaling facilitates a "TCF exchange" on WRE chromatin. Finally, a "reverse switch" mechanism for target genes that are directly repressed by Wnt/β-catenin signaling occurs in Drosophila cells. The diversity of TCF regulatory mechanisms may help to explain how a small group of transcription factors can function in so many different contexts to regulate target gene expression.
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Affiliation(s)
- Ken M Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
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24
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Abstract
Drosophila Groucho (Gro) is the founding member of a family of metazoan corepressors. Gro mediates repression through interactions with a myriad of DNA-binding repressor proteins to direct the silencing of genes involved in many developmental processes, including neurogenesis and patterning of the main body axis, as well as receptor tyrosine kinase/Ras/MAPK, Notch, Wingless (Wg)/Wnt, and Decapentaplegic (Dpp) signaling. Gro mediates repression by multiple molecular mechanisms, depending on the regulatory context. Because Gro is a broadly expressed nuclear factor, whereas its repressor partners display restricted temporal and spatial distribution, it was presumed that this corepressor played permissive rather than instructive roles in development. However, a wide range of studies demonstrates that this is not the case. Gro can sense and integrate many cellular inputs to modulate the expression of variety of genes, making it a versatile corepressor with crucial instructive roles in development and signaling.
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Affiliation(s)
- Wiam Turki-Judeh
- Department of Chemistry & Biochemistry and Molecular Biology Institute, University of California, Los Angeles, California, USA
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25
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Eastwood K, Yin C, Bandyopadhyay M, Bidwai A. New insights into the Orange domain of E(spl)-M8, and the roles of the C-terminal domain in autoinhibition and Groucho recruitment. Mol Cell Biochem 2011; 356:217-25. [PMID: 21789514 DOI: 10.1007/s11010-011-0996-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 06/24/2011] [Indexed: 11/29/2022]
Abstract
CK2 is a Ser/Thr protein kinase that regulates the activity of the Drosophila basic-helix-loop-helix (bHLH) repressor M8 encoded by the Enhancer of split Complex (E(spl)C) during neurogenesis. Specifically, phosphorylation appears to elicit a conformational change in an autoinhibited state of M8 to one that is permissive for repression. We describe biochemical and molecular modeling studies that provide new insights into repression by M8. Our studies implicate the phosphorylation domain in autoinhibition, and indicate that binding of the co-repressor Groucho (Gro) is context-dependent. Molecular modeling indicates that the Orange domain, proposed to be a specificity-determinant, may instead play a structural role, and that a conformational rearrangement of this domain may be necessary for repression. This model also provides a structural mechanism for the behavior of mutant alleles of the m8 gene. The insights gained from these studies should be applicable to the conserved metazoan bHLH repressors of the Hairy and Enhancer of Split (HES) family that are related to Drosophila M8.
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Affiliation(s)
- Karen Eastwood
- Department of Biology, West Virginia University, Life Sciences Building, Morgantown, WV 26506-6057, USA
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26
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Abstract
The human Transducin-like Enhancer of Split (TLE) and mouse homologue, Groucho gene-related protein (GRG), represent a family of conserved non-DNA binding transcriptional modulatory proteins divided into two subgroups based upon size. The long TLE/GRGs consist of four pentadomain proteins that are dedicated co-repressors for multiple transcription factors (TF). The second TLE/GRG subgroup is composed of the Amino-terminal Enhancer of Split (AES) in humans and its mouse homolog GRG5 (AES/GRG5). In contrast to the dedicated co-repressor function of long TLE/GRGs, AES/GRG5 can both positively or negatively modulate various TF as well as non-TF proteins in a long TLE/GRG-dependent or -independent manner. Therefore, AES/GRG5 is a functionally dynamic protein that is not exclusively defined by its role as a long TLE/GRG antagonist. AES/GRG5 may function in various developmental and pathological processes but the functional characteristics of endogenous AES/GRG5 in a physiologically relevant context remains to be determined. Developmental Dynamics 239:2795–2805, 2010. © 2010 Wiley-Liss, Inc.
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Affiliation(s)
- Brandon Beagle
- Department of Anesthesiology, University of Rochester, Rochester, New York 14642, USA
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27
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Wang S, Du J, Tang H, Ding X, Zha M, Xu Z. Expression, purification, crystallization, and preliminary X-ray diffraction analysis of the human TLE1 Q domain. Acta Biochim Biophys Sin (Shanghai) 2011; 43:149-53. [PMID: 21183761 DOI: 10.1093/abbs/gmq116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Human transducin-like enhancer of split 1 (TLE1) plays crucial roles in a number of developmental processes and is involved in pathogenesis of malignancy tumors. The N-terminal glutamine-rich domain (Q domain) of TLE1 mediates its tetramerization and interactions with different DNA-binding transcription factors to regulate Notch and Wnt signaling pathways. To better understand the molecular mechanism of TLE1's functions in these pathways, we cloned, purified, and crystallized the TLE1 Q domain (TLE1-Q). The crystals belong to space group C222(1), with the complete diffraction data of the native and Se-Met TLE1-Q collected to 3.5 and 4.1 Å resolutions, respectively. The phasing-solving and model building are in progress.
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Affiliation(s)
- Su Wang
- Department of Thoracic and Cardiovascular Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China
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Varlakhanova N, Hahm JB, Privalsky ML. Regulation of SMRT corepressor dimerization and composition by MAP kinase phosphorylation. Mol Cell Endocrinol 2011; 332:180-8. [PMID: 20965228 PMCID: PMC3011023 DOI: 10.1016/j.mce.2010.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 09/30/2010] [Accepted: 10/12/2010] [Indexed: 10/18/2022]
Abstract
The SMRT (Silencing Mediator of Retinoid and Thyroid hormone receptors) corepressor mediates gene repression by nuclear receptors and other transcriptional factors. The SMRT protein serves as a key nucleating core that organizes the assembly of a larger corepressor complex. We report here that SMRT interacts with itself to form a protein dimer, and that Erk2, a mitogen-activated protein (MAP) kinase, disrupts this SMRT self-dimerization in vitro and in vivo. Notably Erk2 phosphorylation also results in a re-organization of the overall corepressor complex, characterized by a reduced sedimentation coefficient, partial release of HDAC3, TBL-1, and TBLR-1, and inhibition of transcriptional repression. We propose that SMRT dimers form the central platform on which additional corepressor components assemble, and that kinase signaling modifies the architecture, composition, and function of this complex. These observations contribute to our understanding of how the SMRT corepressor complex assembles and is regulated during cell proliferation and differentiation.
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Affiliation(s)
- Natalia Varlakhanova
- Department of Microbiology, College of Biological Sciences, University of California at Davis, United States
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Ajuria L, Nieva C, Winkler C, Kuo D, Samper N, Andreu MJ, Helman A, González-Crespo S, Paroush Z, Courey AJ, Jiménez G. Capicua DNA-binding sites are general response elements for RTK signaling in Drosophila. Development 2011; 138:915-24. [PMID: 21270056 DOI: 10.1242/dev.057729] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
RTK/Ras/MAPK signaling pathways play key functions in metazoan development, but how they control expression of downstream genes is not well understood. In Drosophila, it is generally assumed that most transcriptional responses to RTK signal activation depend on binding of Ets-family proteins to specific cis-acting sites in target enhancers. Here, we show that several Drosophila RTK pathways control expression of downstream genes through common octameric elements that are binding sites for the HMG-box factor Capicua, a transcriptional repressor that is downregulated by RTK signaling in different contexts. We show that Torso RTK-dependent regulation of terminal gap gene expression in the early embryo critically depends on Capicua octameric sites, and that binding of Capicua to these sites is essential for recruitment of the Groucho co-repressor to the huckebein enhancer in vivo. We then show that subsequent activation of the EGFR RTK pathway in the neuroectodermal region of the embryo controls dorsal-ventral gene expression by downregulating the Capicua protein, and that this control also depends on Capicua octameric motifs. Thus, a similar mechanism of RTK regulation operates during subdivision of the anterior-posterior and dorsal-ventral embryonic axes. We also find that identical DNA octamers mediate Capicua-dependent regulation of another EGFR target in the developing wing. Remarkably, a simple combination of activator-binding sites and Capicua motifs is sufficient to establish complex patterns of gene expression in response to both Torso and EGFR activation in different tissues. We conclude that Capicua octamers are general response elements for RTK signaling in Drosophila.
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Affiliation(s)
- Leiore Ajuria
- Institut de Biologia Molecular de Barcelona-CSIC, Parc Científic de Barcelona, Barcelona, Spain
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30
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Wang S, Xu Z, Tang H, Wei L, Zhao X. [Prokaryotic expression and purification of human TLE1 N-terminal Q domain fragment and production of its polyclonal antibody]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2010; 13:1004-8. [PMID: 21081038 PMCID: PMC6000491 DOI: 10.3779/j.issn.1009-3419.2010.11.02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
背景与目的 TLE1是参与Wnt、Notch以及EGFR信号通路调控的一种重要蛋白。TLE1 N端Q结构域片段通过介导自身寡聚化及与LEF1结合发挥调控作用。本实验旨在构建人TLE1 N端Q区基因在大肠杆菌的融合表达载体,制备并纯化人TLE1 N端Q结构域蛋白片段,制备TLE1 Q结构域多克隆抗体。 方法 以人肺腺癌cDNA库为模板聚合酶链反应(polymerase chain reaction, PCR)特异性扩增TLE1-Q(1-136)基因序列,与pGEX-4T-1质粒连接后转化感受态大肠杆菌E.coli。以异丙基-β-D-硫代半乳糖苷(isopropyl-β-D thiogalactoside, IPTG)诱导表达产生融合蛋白GSTTLE1-Q(1-136)。经亲和层析,Thrombin酶切,FPLC纯化,SDS-PAGE鉴定目的蛋白TLE1-Q(1-136)。免疫家兔,制备多克隆抗体。 结果 测序证实重组表达质粒中的人TLE1 N端Q结构域基因序列正确,成功构建表达型重组质粒pGEX-4T1-TLE1-Q。重组质粒转化大肠杆菌C+后,经诱导,重组蛋白GST-TLE1-Q(1-136)得到表达。SDS-PAGE鉴定示纯化蛋白为目的蛋白人TLE1 N端Q结构域片段TLE1-Q(1-136)。免疫家兔后收获抗血清,ELISA显示抗体效价为1:20 000,具有高度特异性。免疫印迹结果显示,制备的多抗可与TLE1-Q(1-136)蛋白特异性结合。 结论 成功构建了人TLE1 N端Q结构域重组融合蛋白表达质粒pGEX-4T1-TLE1-Q,表达纯化了稳定可溶TLE1 N端Q结构域蛋白TLE1-Q(1-136),制备了人TLE1 N端Q结构域蛋白片段多克隆抗体,为进一步研究TLE1在肺癌生成中的作用奠定了基础。
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Affiliation(s)
- Su Wang
- Department of Thoracic Surgery, Changzheng Hospital, the Second Military Medical University, Shanghai 200003, China
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31
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Soufi A, Sawasdichai A, Shukla A, Noy P, Dafforn T, Smith C, Jayaraman PS, Gaston K. DNA compaction by the higher-order assembly of PRH/Hex homeodomain protein oligomers. Nucleic Acids Res 2010; 38:7513-25. [PMID: 20675722 PMCID: PMC2995075 DOI: 10.1093/nar/gkq659] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein self-organization is essential for the establishment and maintenance of nuclear architecture and for the regulation of gene expression. We have shown previously that the Proline-Rich Homeodomain protein (PRH/Hex) self-assembles to form oligomeric complexes that bind to arrays of PRH binding sites with high affinity and specificity. We have also shown that many PRH target genes contain suitably spaced arrays of PRH sites that allow this protein to bind and regulate transcription. Here, we use analytical ultracentrifugation and electron microscopy to further characterize PRH oligomers. We use the same techniques to show that PRH oligomers bound to long DNA fragments self-associate to form highly ordered assemblies. Electron microscopy and linear dichroism reveal that PRH oligomers can form protein-DNA fibres and that PRH is able to compact DNA in the absence of other proteins. Finally, we show that DNA compaction is not sufficient for the repression of PRH target genes in cells. We conclude that DNA compaction is a consequence of the binding of large PRH oligomers to arrays of binding sites and that PRH is functionally and structurally related to the Lrp/AsnC family of proteins from bacteria and archaea, a group of proteins formerly thought to be without eukaryotic equivalents.
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Affiliation(s)
- Abdenour Soufi
- Institute for Biomedical Research, Birmingham University Medical School, Edgbaston, Birmingham B15 2TT, UK
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32
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Song H, Goetze S, Bischof J, Spichiger-Haeusermann C, Kuster M, Brunner E, Basler K. Coop functions as a corepressor of Pangolin and antagonizes Wingless signaling. Genes Dev 2010; 24:881-6. [PMID: 20439429 DOI: 10.1101/gad.561310] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Wingless (Wg) signaling regulates expression of its target genes via Pangolin and Armadillo, and their interacting cofactors. In the absence of Wg, Pangolin mediates transcriptional repression. In the presence of Wg, Pangolin, Armadillo, and a cohort of coactivators mediate transcriptional activation. Here we uncover Coop (corepressor of Pan) as a Pangolin-interacting protein. Coop and Pangolin form a complex on DNA containing a Pangolin/TCF-binding motif. Overexpression of Coop specifically represses Wg target genes, while loss of Coop function causes derepression. Finally, we show that Coop antagonizes the binding of Armadillo to Pangolin, providing a mechanism for Coop-mediated repression of Wg target gene transcription.
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Affiliation(s)
- Haiyun Song
- Institute of Molecular Life Sciences, University of Zurich, CH-8057 Zurich, Switzerland
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33
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Winkler CJ, Ponce A, Courey AJ. Groucho-mediated repression may result from a histone deacetylase-dependent increase in nucleosome density. PLoS One 2010; 5:e10166. [PMID: 20405012 PMCID: PMC2854148 DOI: 10.1371/journal.pone.0010166] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 03/21/2010] [Indexed: 01/19/2023] Open
Abstract
Groucho (Gro) is a Drosophila melanogaster transcriptional corepressor that directly interacts with the histone deacetylase Rpd3. Although previous studies suggest that this interaction is required for repression of Gro-responsive reporters in cultured cells, the in vivo significance of this interaction and the mechanism by which it leads to repression remain largely unexplored. In this study, we show that Gro is partially dependent on Rpd3 for repression, supporting the idea that Rpd3-mediated repression is one mode of Gro-mediated repression. We demonstrate that Gro colocalizes with Rpd3 to the chromatin of a target gene and that this is accompanied by the deacetylation of specific lysines within the N-terminal tails of histones H3 and H4. Gro overexpression leads to wing patterning defects and ectopic repression in the wing disc of transcription directed by the vestigial quadrant enhancer. These effects are reversed by the histone deacetylase inhibitors TSA and HC-Toxin and by the reduction of Rpd3 gene dosage. Furthermore, repression of the vestigial quadrant enhancer is accompanied by a Gro-mediated increase in nucleosome density, an effect that is reversed by histone deacetylase inhibitors. We propose a model in which Gro-mediated histone deacetylation results in increased nucleosome density leading to transcriptional repression.
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Affiliation(s)
- Clint J. Winkler
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Alberto Ponce
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Albert J. Courey
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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34
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Groucho corepressor functions as a cofactor for the Knirps short-range transcriptional repressor. Proc Natl Acad Sci U S A 2009; 106:17314-9. [PMID: 19805071 DOI: 10.1073/pnas.0904507106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite the pervasive roles for repressors in transcriptional control, the range of action of these proteins on cis regulatory elements remains poorly understood. Knirps has essential roles in patterning the Drosophila embryo by means of short-range repression, an activity that is essential for proper regulation of complex transcriptional control elements. Short-range repressors function in a local fashion to interfere with the activity of activators or basal promoters within approximately 100 bp. In contrast, long-range repressors such as Hairy act over distances >1 kb. The functional distinction between these two classes of repressors has been suggested to stem from the differential recruitment of the CtBP corepressor to short-range repressors and Groucho to long-range repressors. Contrary to this differential recruitment model, we report that Groucho is a functional part of the Knirps short-range repression complex. The corepressor interaction is mediated via an eh-1 like motif present in the N terminus and a conserved region present in the central portion of Knirps. We also show that this interaction is important for the CtBP-independent repression activity of Knirps and is required for regulation of even-skipped. Our study uncovers a previously uncharacterized interaction between proteins previously thought to function in distinct repression pathways, and indicates that the Groucho corepressor can be differentially harnessed to execute short- and long-range repression.
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35
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Abstract
The PRH (proline-rich homeodomain) [also known as Hex (haematopoietically expressed homeobox)] protein is a transcription factor that functions as an important regulator of vertebrate development and many other processes in the adult including haematopoiesis. The Groucho/TLE (transducin-like enhancer) family of co-repressor proteins also regulate development and modulate the activity of many DNA-binding transcription factors during a range of diverse cellular processes including haematopoiesis. We have shown previously that PRH is a repressor of transcription in haematopoietic cells and that an Eh-1 (Engrailed homology) motif present within the N-terminal transcription repression domain of PRH mediates binding to Groucho/TLE proteins and enables co-repression. In the present study we demonstrate that PRH regulates the nuclear retention of TLE proteins during cellular fractionation. We show that transcriptional repression and the nuclear retention of TLE proteins requires PRH to bind to both TLE and DNA. In addition, we characterize a trans-dominant-negative PRH protein that inhibits wild-type PRH activity by sequestering TLE proteins to specific subnuclear domains. These results demonstrate that transcriptional repression by PRH is dependent on TLE availability and suggest that subnuclear localization of TLE plays an important role in transcriptional repression by PRH.
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36
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A role of Pygopus as an anti-repressor in facilitating Wnt-dependent transcription. Proc Natl Acad Sci U S A 2008; 105:19324-9. [PMID: 19036929 DOI: 10.1073/pnas.0806098105] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Wnt/beta-catenin signaling controls animal development and tissue homeostasis, and is also an important cancer pathway. Pygopus (Pygo) is a conserved nuclear Wnt signaling component that is essential for Wingless-induced transcription throughout Drosophila development. It associates with Armadillo/beta-catenin and T cell factor (TCF) through the Legless/BCL9 adaptor, but its molecular function in TCF-mediated transcription is unknown. Here, we use a groucho-null allele to show that Groucho represses Wingless target genes during Drosophila development. Interestingly, groucho pygo double-mutants revealed that Pygo is not obligatory for transcriptional and phenotypic Wingless signaling outputs if the interaction between Groucho and Drosophila TCF is compromised genetically. Pygo function is also non-essential for Wingless outputs in the absence of other transcriptional antagonists of Wingless signaling. This indicates an anti-repressor function of Pygo: we propose that Pygo predisposes Drosophila TCF target genes for rapid Wingless-induced transcription, or that it protects them against premature shut-down.
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37
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Abstract
The WD-repeat-containing proteins form a very large family that is diverse in both its function and domain structure. Within all these proteins the WD-repeat domains are thought to have two common features: the domain folds into a beta propeller; and the domains form a platform without any catalytic activity on which multiple protein complexes assemble reversibly. The fact that these proteins play such key roles in the formation of protein-protein complexes in nearly all the major pathways and organelles unique to eukaryotic cells has two important implications. It supports both their ancient and proto eukaryotic origins and supports a likely association with many genetic diseases.
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Affiliation(s)
- Temple F Smith
- BioMolecular Engineering Research Center, College of Engineering, Boston University, 36 Cummington Street, Boston, MA 02215, USA.
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38
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Cinnamon E, Paroush Z. Context-dependent regulation of Groucho/TLE-mediated repression. Curr Opin Genet Dev 2008; 18:435-40. [PMID: 18721877 DOI: 10.1016/j.gde.2008.07.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 07/14/2008] [Accepted: 07/23/2008] [Indexed: 01/15/2023]
Abstract
Groucho/TLE proteins are global corepressors that are recruited to target promoters by different families of DNA-binding repressors. As these corepressors are widely expressed, the long-standing view had been that Groucho/TLE-mediated repression is regulated solely by the spatial and temporal distribution of partner repressors. It has recently emerged, however, that Groucho/TLE repressor activity is itself regulated, in a signal induced, context-dependent manner. Here we review the essential roles played by Groucho/TLE factors in different cell-signalling processes that illustrate different modes for regulating Groucho/TLE-mediated repression: (i) via the expression of partner repressors; (ii) by competition with coactivators and (iii) through post-translational modifications of Groucho/TLE. We also discuss how the intrinsic properties of repressors can result in differential responses to Groucho/TLE regulation.
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Affiliation(s)
- Einat Cinnamon
- Department of Biochemistry, Faculty of Medicine, The Hebrew University, PO Box 12272, Jerusalem 91120, Israel.
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39
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Zeng YB, Zhang DM, Li H, Sun H. Binding of Ni2+ to a histidine- and glutamine-rich protein, Hpn-like. J Biol Inorg Chem 2008; 13:1121-31. [PMID: 18563455 DOI: 10.1007/s00775-008-0397-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 06/04/2008] [Indexed: 12/28/2022]
Abstract
Hpn-like (Hpnl) protein, encoded by the hpnl gene in Helicobacter pylori and featuring a histidine-rich and two glutamine-rich motifs, can render nickel tolerance to H. pylori when the external nickel level reaches toxic limits. We found that the recombinant Hpnl exists as an oligomer in the native state and binds to two molar equivalents of nickel ions per monomer with a dissociation constant of 3.8 microM. Nickel could be released from Hpnl either at acidic pH (pH(1/2) 4.6) or in the presence of chelate ligands, such as EDTA (t(1/2) = 220, 355, and 716 min at pH 6.0, 7.0, and 7.5, respectively). Our combined spectroscopic data show that nickel ion coordinates to a nitrogen of a histidine residue possibly with a coordination number of four (square-planar geometry) or five. The growth of Escherichia coli cells with or without the hpnl gene implied a protective role of Hpnl under higher concentrations of external nickel ions. Hpnl may serve a role in binding/storage or detoxification of excess nickel ions.
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Affiliation(s)
- Yi-Bo Zeng
- Department of Chemistry and Open Laboratory of Chemical Biology, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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40
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Allen ND. Temporal and epigenetic regulation of neurodevelopmental plasticity. Philos Trans R Soc Lond B Biol Sci 2008; 363:23-38. [PMID: 17311782 PMCID: PMC2605484 DOI: 10.1098/rstb.2006.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The anticipated therapeutic uses of neural stem cells depend on their ability to retain a certain level of developmental plasticity. In particular, cells must respond to developmental manipulations designed to specify precise neural fates. Studies in vivo and in vitro have shown that the developmental potential of neural progenitor cells changes and becomes progressively restricted with time. For in vitro cultured neural progenitors, it is those derived from embryonic stem cells that exhibit the greatest developmental potential. It is clear that both extrinsic and intrinsic mechanisms determine the developmental potential of neural progenitors and that epigenetic, or chromatin structural, changes regulate and coordinate hierarchical changes in fate-determining gene expression. Here, we review the temporal changes in developmental plasticity of neural progenitor cells and discuss the epigenetic mechanisms that underpin these changes. We propose that understanding the processes of epigenetic programming within the neural lineage is likely to lead to the development of more rationale strategies for cell reprogramming that may be used to expand the developmental potential of otherwise restricted progenitor populations.
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Affiliation(s)
- Nicholas D Allen
- School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, UK.
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41
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Abstract
Transcriptional repressor proteins play key roles in the control of gene expression in development. For the Drosophila embryo, the following two functional classes of repressors have been described: short-range repressors such as Knirps that locally inhibit the activity of enhancers and long-range repressors such as Hairy that can dominantly inhibit distal elements. Several long-range repressors interact with Groucho, a conserved corepressor that is homologous to mammalian TLE proteins. Groucho interacts with histone deacetylases and histone proteins, suggesting that it may effect repression by means of chromatin modification; however, it is not known how long-range effects are mediated. Using embryo chromatin immunoprecipitation, we have analyzed a Hairy-repressible gene in the embryo during activation and repression. When inactivated, repressors, activators, and coactivators cooccupy the promoter, suggesting that repression is not accomplished by the displacement of activators or coactivators. Strikingly, the Groucho corepressor is found to be recruited to the transcribed region of the gene, contacting a region of several kilobases, concomitant with a loss of histone H3 and H4 acetylation. Groucho has been shown to form higher-order complexes in vitro; thus, our observations suggest that long-range effects may be mediated by a "spreading" mechanism, modifying chromatin over extensive regions to inhibit transcription.
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42
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Abstract
The Groucho family of co-repressor proteins are essential for development and may also have a role in some human cancers.
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Affiliation(s)
- Barbara H Jennings
- Developmental Genetics Laboratory, Cancer Research UK, Lincoln's Inn Fields, London, WC2A 3PX, UK
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43
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Choi HK, Choi KC, Kang HB, Kim HC, Lee YH, Haam S, Park HG, Yoon HG. Function of multiple Lis-Homology domain/WD-40 repeat-containing proteins in feed-forward transcriptional repression by silencing mediator for retinoic and thyroid receptor/nuclear receptor corepressor complexes. Mol Endocrinol 2008; 22:1093-104. [PMID: 18202150 DOI: 10.1210/me.2007-0396] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lis-homology (LisH) motifs are involved in protein dimerization, and the discovery of the conserved N-terminal LisH domain in transducin beta-like protein 1 and its receptor (TBL1 and TBLR1) led us to examine the role of this domain in transcriptional repression. Here we show that multiple beta-transducin (WD-40) repeat-containing proteins interact to form oligomers in solution and that oligomerization depends on the presence of the LisH domain in each protein. Repression of transcription, as assayed using Gal4 fusion proteins, also depended on the presence of the LisH domain, suggesting that oligomerization is a prerequisite for efficient transcriptional repression. Furthermore, we show that the LisH domain is responsible for the binding to the hypoacetylated histone H4 tail and for stable chromatin targeting by the nuclear receptor corepressor complex. Mutations in conserved residues in the LisH motif of TBL1 and TBLR1 block histone binding, oligomerization, and transcriptional repression, supporting the functional importance of the LisH motif in transcriptional repression. Our results indicate that another WD-40 protein, TBL3, also preferentially binds to the N-terminal domain of TBL1 and TBLR1, and forms oligomers with other WD-40 proteins. Finally, we observed that the WD-40 proteins RbAp46 and RbAp48 of the sin3A corepressor complex failed to dimerize. We also found the specific interaction UbcH/E2 with TBL1, but not RbAp46/48. Altogether, our results thus indicate that the presence of multiple LisH/WD-40 repeat containing proteins is exclusive to nuclear receptor corepressor/ silencing mediator for retinoic and thyroid receptor complexes compared with other class 1 histone deacetylase-containing corepessor complexes.
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Affiliation(s)
- Hyo-Kyoung Choi
- Department of Biochemistry and Molecular Biology, Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, Seoul 120-752, South Korea
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44
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Repression by Groucho/TLE/Grg proteins: genomic site recruitment generates compacted chromatin in vitro and impairs activator binding in vivo. Mol Cell 2008; 28:291-303. [PMID: 17964267 DOI: 10.1016/j.molcel.2007.10.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 07/13/2007] [Accepted: 08/12/2007] [Indexed: 11/21/2022]
Abstract
Groucho-related (Gro/TLE/Grg) corepressors meditate embryonic segmentation, dorsal-ventral patterning, neurogenesis, and Notch and Wnt signaling. Although Gro/TLE/Grgs disrupt activator complexes and recruit histone deacetylases (HDAC), activator complexes can be disrupted in various ways, HDAC recruitment does not account for full corepressor activity, and a direct role for Gro/TLE/Grg binding and altering chromatin structure has not been explored. Using diverse chromatin substrates in vitro, we show that Grg3 creates higher-order, condensed complexes of polynucleosome arrays. Surprisingly, such complexes are in an open, exposed configuration. We find that chromatin binding enables Grg3 recruitment by a transcription factor and the creation of a closed, poorly accessible domain spanning three to four nucleosomes. Targeted recruitment of Grg3 blankets a similar-sized region in vivo, impairing activator recruitment and repressing transcription. These activities of a Groucho protein represent a newly discovered mechanism which differs from that of other classes of corepressors.
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45
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Goodfellow H, Krejcí A, Moshkin Y, Verrijzer CP, Karch F, Bray SJ. Gene-specific targeting of the histone chaperone asf1 to mediate silencing. Dev Cell 2008; 13:593-600. [PMID: 17925233 DOI: 10.1016/j.devcel.2007.08.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 07/13/2007] [Accepted: 08/31/2007] [Indexed: 11/17/2022]
Abstract
The histone chaperone Asf1 assists in chromatin assembly and remodeling during replication, transcription activation, and gene silencing. However, it has been unclear to what extent Asf1 could be targeted to specific loci via interactions with sequence-specific DNA-binding proteins. Here, we show that Asf1 contributes to the repression of Notch target genes, as depletion of Asf1 in cells by RNAi causes derepression of the E(spl) Notch-inducible genes. Conversely, overexpression of Asf1 in vivo results in decreased expression of target genes and produces phenotypes that are strongly modified (enhanced and suppressed) by mutations affecting the Notch pathway, but not by mutations in other signaling pathways. Asf1 can be coprecipitated with the DNA-binding protein Su(H) and the corepressor Hairless and interacts directly with two components of this complex, Hairless and SKIP. Thus, in addition to playing more general roles in chromatin dynamics, Asf1 is directed via interactions with sequence-specific complexes to mediate silencing of specific target genes.
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Affiliation(s)
- Henry Goodfellow
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom
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46
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Liotta D, Han J, Elgar S, Garvey C, Han Z, Taylor MV. The Him gene reveals a balance of inputs controlling muscle differentiation in Drosophila. Curr Biol 2007; 17:1409-13. [PMID: 17702578 PMCID: PMC1955682 DOI: 10.1016/j.cub.2007.07.039] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 06/28/2007] [Accepted: 07/13/2007] [Indexed: 11/23/2022]
Abstract
Tissue development requires the controlled regulation of cell-differentiation programs. In muscle, the Mef2 transcription factor binds to and activates the expression of many genes and has a major positive role in the orchestration of differentiation [1–4]. However, little is known about how Mef2 activity is regulated in vivo during development. Here, we characterize a gene, Holes in muscle (Him), which our results indicate is part of this control in Drosophila. Him expression rapidly declines as embryonic muscle differentiates, and consistent with this, Him overexpression inhibits muscle differentiation. This inhibitory effect is suppressed by mef2, implicating Him in the mef2 pathway. We then found that Him downregulates the transcriptional activity of Mef2 in both cell culture and in vivo. Furthermore, Him protein binds Groucho, a conserved, transcriptional corepressor, through a WRPW motif and requires this motif and groucho function to inhibit both muscle differentiation and Mef2 activity during development. Together, our results identify a mechanism that can inhibit muscle differentiation in vivo. We conclude that a balance of positive and negative inputs, including Mef2, Him, and Groucho, controls muscle differentiation during Drosophila development and suggest that one outcome is to hold developing muscle cells in a state with differentiation genes poised to be expressed.
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Affiliation(s)
- David Liotta
- Cardiff School of Biosciences, Cardiff University Main Building, Cardiff CF10 3TL, United Kingdom
| | - Jun Han
- Cardiff School of Biosciences, Cardiff University Main Building, Cardiff CF10 3TL, United Kingdom
| | - Stuart Elgar
- Cardiff School of Biosciences, Cardiff University Main Building, Cardiff CF10 3TL, United Kingdom
| | - Clare Garvey
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Zhe Han
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Michael V. Taylor
- Cardiff School of Biosciences, Cardiff University Main Building, Cardiff CF10 3TL, United Kingdom
- Corresponding author
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Differential in vivo requirements for oligomerization during Groucho-mediated repression. EMBO Rep 2007; 9:76-83. [PMID: 18034187 DOI: 10.1038/sj.embor.7401122] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 10/17/2007] [Accepted: 10/19/2007] [Indexed: 11/09/2022] Open
Abstract
The Groucho (Gro)/transducin-like enhancer of split family of transcriptional corepressors are implicated in many signalling pathways that are important in development and disease, including those mediated by Notch, Wnt and Hedgehog. Here, we describe a genetic screen in Drosophila that yielded 50 new gro alleles, including the first protein-null allele, and has two mutations in the conserved Q oligomerization domain that have been proposed to have an essential role in corepressor activity. One of these latter mutations, encoding an amino-terminal protein truncation that lacks part of the Q domain, abolishes oligomerization in vitro and renders the protein unstable in vivo. Nevertheless, the mutation is not a null: maternal mutant embryos have intermediate segmentation phenotypes and relatively normal terminal patterning suggesting that the mutant protein retains partial corepressor activity. Our results show that homo-oligomerization of Gro is not obligatory for its action in vivo, and that Gro represses transcription through more than one molecular mechanism.
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Buscarlet M, Stifani S. The 'Marx' of Groucho on development and disease. Trends Cell Biol 2007; 17:353-61. [PMID: 17643306 DOI: 10.1016/j.tcb.2007.07.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/19/2007] [Accepted: 07/02/2007] [Indexed: 10/23/2022]
Abstract
Groucho proteins are abundant and broadly expressed nuclear factors that lack intrinsic DNA-binding activity but can interact with a variety of DNA-binding proteins. The recruitment of Groucho to specific gene regulatory sequences results in transcriptional repression. In both invertebrates and vertebrates, Groucho family members act as important regulators of several signaling mechanisms, including the Notch, Wingless/Wnt and Dpp/BMP/TGF-beta signaling pathways. Recent studies of embryonic development in several species point to an important role for Groucho in the regulation of multiple patterning and differentiation events. Moreover, a deregulated expression of human Groucho family members is correlated with several neoplastic conditions. Here we focus on the functions of Groucho proteins during body patterning and their implication in tumorigenesis.
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Affiliation(s)
- Manuel Buscarlet
- Center for Neuronal Survival, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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Kelly DF, Lake RJ, Walz T, Artavanis-Tsakonas S. Conformational variability of the intracellular domain of Drosophila Notch and its interaction with Suppressor of Hairless. Proc Natl Acad Sci U S A 2007; 104:9591-6. [PMID: 17535912 PMCID: PMC1887580 DOI: 10.1073/pnas.0702887104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Notch receptor is the central element in an evolutionarily conserved signal transduction pathway that controls cell fates in metazoans. Receptor-ligand interactions trigger a cascade of proteolytic events that release the entire Notch intracellular domain (NICD) from the membrane, permitting its translocation into the nucleus and participation in a transcriptionally active complex. Using electron microscopy, we examined the structure of NICD and its interaction with the DNA-binding effector of Notch signaling, Suppressor of Hairless [Su(H)]. In conjunction with biochemical analyses, we found that Drosophila NICD is monomeric and exists in two primary conformational states, only one of which can bind Su(H). Furthermore, we show that changes in divalent cation concentrations lead to NICD self-association, which seems to be mediated by the polyglutamine-containing, opa-repeat region of NICD. Our study suggests that conformational modulation of NICD may define a mechanism of Notch pathway control.
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Affiliation(s)
- Deborah F. Kelly
- *Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
| | - Robert J. Lake
- Massachusetts General Hospital Cancer Center, 149 13th Street, Charlestown, MA 02129; and
| | - Thomas Walz
- *Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
| | - Spyros Artavanis-Tsakonas
- *Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
- Massachusetts General Hospital Cancer Center, 149 13th Street, Charlestown, MA 02129; and
- Collège de France, 75231 Paris, France
- To whom correspondence should be addressed. E-mail:
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50
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Guo L, Han A, Bates DL, Cao J, Chen L. Crystal structure of a conserved N-terminal domain of histone deacetylase 4 reveals functional insights into glutamine-rich domains. Proc Natl Acad Sci U S A 2007; 104:4297-302. [PMID: 17360518 PMCID: PMC1838596 DOI: 10.1073/pnas.0608041104] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glutamine-rich sequences exist in a wide range of proteins across multiple species. A subset of glutamine-rich sequences has been shown to form amyloid fibers implicated in human diseases. The physiological functions of these sequence motifs are not well understood, partly because of the lack of structural information. Here we have determined a high-resolution structure of a glutamine-rich domain from human histone deacetylase 4 (HDAC4) by x-ray crystallography. The glutamine-rich domain of HDAC4 (19 glutamines of 68 residues) folds into a straight alpha-helix that assembles as a tetramer. In contrast to most coiled coil proteins, the HDAC4 tetramer lacks regularly arranged apolar residues and an extended hydrophobic core. Instead, the protein interfaces consist of multiple hydrophobic patches interspersed with polar interaction networks, wherein clusters of glutamines engage in extensive intra- and interhelical interactions. In solution, the HDAC4 tetramer undergoes rapid equilibrium with monomer and intermediate species. Structure-guided mutations that expand or disrupt hydrophobic patches drive the equilibrium toward the tetramer or monomer, respectively. We propose that a general role of glutamine-rich motifs be to mediate protein-protein interactions characteristic of a large component of polar interaction networks that may facilitate reversible assembly and disassembly of protein complexes.
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Affiliation(s)
- Liang Guo
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215
| | - Aidong Han
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215
- *To whom correspondence should be sent at the present address:
Molecular and Computational Biology, Room 204c, University of Southern California, Los Angeles, CA 90089-2910. E-mail:
| | - Darren L. Bates
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215
| | - Jue Cao
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215
| | - Lin Chen
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215
- *To whom correspondence should be sent at the present address:
Molecular and Computational Biology, Room 204c, University of Southern California, Los Angeles, CA 90089-2910. E-mail:
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