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Niederhuber MJ, Leatham-Jensen M, McKay DJ. The SWI/SNF nucleosome remodeler constrains enhancer activity during Drosophila wing development. Genetics 2024; 226:iyad196. [PMID: 37949841 PMCID: PMC10847718 DOI: 10.1093/genetics/iyad196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/05/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023] Open
Abstract
Chromatin remodeling is central to the dynamic changes in gene expression that drive cell fate determination. During development, the sets of enhancers that are accessible for use change globally as cells transition between stages. While transcription factors and nucleosome remodelers are known to work together to control enhancer accessibility, it is unclear how the short stretches of DNA that they individually unmask yield the kilobase-sized accessible regions characteristic of active enhancers. Here, we performed a genetic screen to investigate the role of nucleosome remodelers in control of dynamic enhancer activity. We find that the Drosophila Switch/Sucrose Non-Fermenting complex, BAP, is required for repression of a temporally dynamic enhancer, brdisc. Contrary to expectations, we find that the BAP-specific subunit Osa is dispensable for mediating changes in chromatin accessibility between the early and late stages of wing development. Instead, we find that Osa is required to constrain the levels of brdisc activity when the enhancer is normally active. Genome-wide profiling reveals that Osa directly binds brdisc as well as thousands of other developmentally dynamic regulatory sites, including multiple genes encoding components and targets of the Notch signaling pathway. Transgenic reporter analyses demonstrate that Osa is required for activation and for constraint of different sets of target enhancers in the same cells. Moreover, Osa loss results in hyperactivation of the Notch ligand Delta and development of ectopic sensory structures patterned by Notch signaling early in development. Together, these findings indicate that proper constraint of enhancer activity is necessary for regulation of dose-dependent developmental events.
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Affiliation(s)
- Matthew J Niederhuber
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mary Leatham-Jensen
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Daniel J McKay
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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2
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Tian Y, Smith-Bolton RK. Regulation of growth and cell fate during tissue regeneration by the two SWI/SNF chromatin-remodeling complexes of Drosophila. Genetics 2021; 217:1-16. [PMID: 33683366 DOI: 10.1093/genetics/iyaa028] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 11/10/2020] [Indexed: 11/12/2022] Open
Abstract
To regenerate, damaged tissue must heal the wound, regrow to the proper size, replace the correct cell types, and return to the normal gene-expression program. However, the mechanisms that temporally and spatially control the activation or repression of important genes during regeneration are not fully understood. To determine the role that chromatin modifiers play in regulating gene expression after tissue damage, we induced ablation in Drosophila melanogaster imaginal wing discs, and screened for chromatin regulators that are required for epithelial tissue regeneration. Here, we show that many of these genes are indeed important for promoting or constraining regeneration. Specifically, the two SWI/SNF chromatin-remodeling complexes play distinct roles in regulating different aspects of regeneration. The PBAP complex regulates regenerative growth and developmental timing, and is required for the expression of JNK signaling targets and the growth promoter Myc. By contrast, the BAP complex ensures correct patterning and cell fate by stabilizing the expression of the posterior gene engrailed. Thus, both SWI/SNF complexes are essential for proper gene expression during tissue regeneration, but they play distinct roles in regulating growth and cell fate.
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Affiliation(s)
- Yuan Tian
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rachel K Smith-Bolton
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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3
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Hu X, Li M, Hao X, Lu Y, Zhang L, Wu G. The Osa-Containing SWI/SNF Chromatin-Remodeling Complex Is Required in the Germline Differentiation Niche for Germline Stem Cell Progeny Differentiation. Genes (Basel) 2021; 12:genes12030363. [PMID: 33806269 PMCID: PMC7998989 DOI: 10.3390/genes12030363] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 12/22/2022] Open
Abstract
The Drosophila ovary is recognized as a powerful model to study stem cell self-renewal and differentiation. Decapentaplegic (Dpp) is secreted from the germline stem cell (GSC) niche to activate Bone Morphogenic Protein (BMP) signaling in GSCs for their self-renewal and is restricted in the differentiation niche for daughter cell differentiation. Here, we report that Switch/sucrose non-fermentable (SWI/SNF) component Osa depletion in escort cells (ECs) results in a blockage of GSC progeny differentiation. Further molecular and genetic analyses suggest that the defective germline differentiation is partially attributed to the elevated dpp transcription in ECs. Moreover, ectopic Engrailed (En) expression in osa-depleted ECs partially contributes to upregulated dpp transcription. Furthermore, we show that Osa regulates germline differentiation in a Brahma (Brm)-associated protein (BAP)-complex-dependent manner. Additionally, the loss of EC long cellular processes upon osa depletion may also partly contribute to the germline differentiation defect. Taken together, these data suggest that the epigenetic factor Osa plays an important role in controlling EC characteristics and germline lineage differentiation.
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Affiliation(s)
- Xiaolong Hu
- State Key Laboratory of Microbial Metabolism, The Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; (X.H.); (M.L.)
| | - Mengjie Li
- State Key Laboratory of Microbial Metabolism, The Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; (X.H.); (M.L.)
| | - Xue Hao
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; (X.H.); (Y.L.); (L.Z.)
| | - Yi Lu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; (X.H.); (Y.L.); (L.Z.)
| | - Lei Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China; (X.H.); (Y.L.); (L.Z.)
- School of Life Science and Technology, Shanghai Tech University, Shanghai 201210, China
- Bio-Research Innovation Center, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Suzhou 215121, China
| | - Geng Wu
- State Key Laboratory of Microbial Metabolism, The Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China; (X.H.); (M.L.)
- Correspondence:
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4
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Sun Q, Jiang Y, Yan X, Fan M, Zhang X, Xu H, Liao Z. Molecular Characterization of a Novel Shell Matrix Protein With PDZ Domain From Mytilus coruscus. Front Physiol 2020; 11:543758. [PMID: 33123020 PMCID: PMC7573561 DOI: 10.3389/fphys.2020.543758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 09/04/2020] [Indexed: 11/16/2022] Open
Abstract
Mollusk shells are products of biomineralization and possess excellent mechanical properties, and shell matrix proteins (SMPs) have important functions in shell formation. A novel SMP with a PDZ domain (PDZ-domain-containing-protein-1, PDCP-1) was identified from the shell matrices of Mytilus coruscus. In this study, the gene expression, function, and location of PDCP-1 were analyzed. PDCP-1 was characterized as an ∼70 kDa protein with a PDZ (postsynaptic density/discs large/zonula occludes) domain and a ZM (ZASP-like motif) domain. The PDCP-1 gene has a high expression level and specific location in the foot, mantle and adductor muscle. Recombinantly expressed PDCP-1 (rPDCP-1) altered the morphology of calcite crystals, the polymorph of calcite crystals, binding with both calcite and aragonite crystals, and inhibition of the crystallization rate of calcite crystals. In addition, anti-rPDCP-1 antibody was prepared, and immunohistochemistry and immunofluorescence analyses revealed the specific location of PDCP-1 in the mantle, the adductor muscle, and the aragonite (nacre and myostracum) layer of the shell, suggesting multiple functions of PDCP-1 in biomineralization, muscle-shell attachment, and muscle attraction. Furthermore, pull-down analysis revealed 19 protein partners of PDCP-1 from the shell matrices, which accordingly provided a possible interaction network of PDCP-1 in the shell. These results expand the understanding of the functions of PDZ-domain-containing proteins (PDCPs) in biomineralization and the supramolecular chemistry that contributes to shell formation.
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Regulation of the Mammalian SWI/SNF Family of Chromatin Remodeling Enzymes by Phosphorylation during Myogenesis. BIOLOGY 2020; 9:biology9070152. [PMID: 32635263 PMCID: PMC7407365 DOI: 10.3390/biology9070152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 11/16/2022]
Abstract
Myogenesis is the biological process by which skeletal muscle tissue forms. Regulation of myogenesis involves a variety of conventional, epigenetic, and epigenomic mechanisms that control chromatin remodeling, DNA methylation, histone modification, and activation of transcription factors. Chromatin remodeling enzymes utilize ATP hydrolysis to alter nucleosome structure and/or positioning. The mammalian SWItch/Sucrose Non-Fermentable (mSWI/SNF) family of chromatin remodeling enzymes is essential for myogenesis. Here we review diverse and novel mechanisms of regulation of mSWI/SNF enzymes by kinases and phosphatases. The integration of classic signaling pathways with chromatin remodeling enzyme function impacts myoblast viability and proliferation as well as differentiation. Regulated processes include the assembly of the mSWI/SNF enzyme complex, choice of subunits to be incorporated into the complex, and sub-nuclear localization of enzyme subunits. Together these processes influence the chromatin remodeling and gene expression events that control myoblast function and the induction of tissue-specific genes during differentiation.
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Rosales-Vega M, Hernández-Becerril A, Murillo-Maldonado JM, Zurita M, Vázquez M. The role of the trithorax group TnaA isoforms in Hox gene expression, and in Drosophila late development. PLoS One 2018; 13:e0206587. [PMID: 30372466 PMCID: PMC6205608 DOI: 10.1371/journal.pone.0206587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/16/2018] [Indexed: 11/18/2022] Open
Abstract
Regulation of developmental gene expression in eukaryotes involves several levels. One of them is the maintenance of gene expression along the life of the animal once it is started by different triggers early in development. One of the questions in the field is when in developmental time, the animal start to use the different maintenance mechanisms. The trithorax group (TrxG) of genes was first characterized as essential for maintaining homeotic gene expression. The TrxG gene tonalli interacts genetically and physically with genes and subunits of the BRAHMA BAP chromatin remodeling complex and encodes TnaA proteins with putative E3 SUMO-ligase activity. In contrast to the phenocritic lethal phase of animals with mutations in other TrxG genes, tna mutant individuals die late in development. In this study we determined the requirements of TnaA for survival at pupal and adult stages, in different tna mutant genotypes where we corroborate the lack of TnaA proteins, and the presence of adult homeotic loss-of-function phenotypes. We also investigated whether the absence of TnaA in haltere and leg larval imaginal discs affects the presence of the homeotic proteins Ultrabithorax and Sex combs reduced respectively by using some of the characterized genotypes and more finely by generating TnaA defective clones induced at different stages of development. We found that, tna is not required for growth or survival of imaginal disc cells and that it is a fine modulator of homeotic gene expression.
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Affiliation(s)
- Marco Rosales-Vega
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Adriana Hernández-Becerril
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Juan Manuel Murillo-Maldonado
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Querétaro, México
| | - Mario Zurita
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Martha Vázquez
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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7
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Morrison CA, Chen H, Cook T, Brown S, Treisman JE. Glass promotes the differentiation of neuronal and non-neuronal cell types in the Drosophila eye. PLoS Genet 2018; 14:e1007173. [PMID: 29324767 PMCID: PMC5783423 DOI: 10.1371/journal.pgen.1007173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 01/24/2018] [Accepted: 12/29/2017] [Indexed: 11/18/2022] Open
Abstract
Transcriptional regulators can specify different cell types from a pool of equivalent progenitors by activating distinct developmental programs. The Glass transcription factor is expressed in all progenitors in the developing Drosophila eye, and is maintained in both neuronal and non-neuronal cell types. Glass is required for neuronal progenitors to differentiate as photoreceptors, but its role in non-neuronal cone and pigment cells is unknown. To determine whether Glass activity is limited to neuronal lineages, we compared the effects of misexpressing it in neuroblasts of the larval brain and in epithelial cells of the wing disc. Glass activated overlapping but distinct sets of genes in these neuronal and non-neuronal contexts, including markers of photoreceptors, cone cells and pigment cells. Coexpression of other transcription factors such as Pax2, Eyes absent, Lozenge and Escargot enabled Glass to induce additional genes characteristic of the non-neuronal cell types. Cell type-specific glass mutations generated in cone or pigment cells using somatic CRISPR revealed autonomous developmental defects, and expressing Glass specifically in these cells partially rescued glass mutant phenotypes. These results indicate that Glass is a determinant of organ identity that acts in both neuronal and non-neuronal cells to promote their differentiation into functional components of the eye.
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Affiliation(s)
- Carolyn A. Morrison
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Hao Chen
- Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Tiffany Cook
- Center of Molecular Medicine and Genomics and Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Stuart Brown
- Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
| | - Jessica E. Treisman
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, NYU School of Medicine, New York, NY, United States of America
- * E-mail:
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8
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Sim JCH, White SM, Lockhart PJ. ARID1B-mediated disorders: Mutations and possible mechanisms. Intractable Rare Dis Res 2015; 4:17-23. [PMID: 25674384 PMCID: PMC4322591 DOI: 10.5582/irdr.2014.01021] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/22/2022] Open
Abstract
Mutations in the gene encoding AT-rich interactive domain-containing protein 1B (ARID1B) were recently associated with multiple syndromes characterized by developmental delay and intellectual disability, in addition to nonsyndromic intellectual disability. While the majority of ARID1B mutations identified to date are predicted to result in haploinsufficiency, the underlying pathogenic mechanisms have yet to be fully understood. ARID1B is a DNA-binding subunit of the Brahma-associated factor chromatin remodelling complexes, which play a key role in the regulation of gene activity. The function of remodelling complexes can be regulated by their subunit composition, and there is some evidence that ARID1B is a component of the neuron-specific chromatin remodelling complex. This complex is involved in the regulation of stem/progenitor cells exiting the cell cycle and differentiating into postmitotic neurons. Recent research has indicated that alterations in the cell cycle contribute to the underlying pathogenesis of syndromes associated with ARID1B haploinsufficiency in fibroblasts derived from affected individuals. This review describes studies linking ARID1B to neurodevelopmental disorders and it summarizes the function of ARID1B to provide insights into the pathogenic mechanisms underlying ARID1B-mediated disorders. In conclusion, ARID1B is likely to play a key role in neurodevelopment and reduced levels of wild-type protein compromise normal brain development. Additional studies are required to determine the mechanisms by which impaired neural development contributes to the intellectual disability and speech impairment that are consistently observed in individuals with ARID1B haploinsufficiency.
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Affiliation(s)
- Joe C. H. Sim
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Susan M White
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul J. Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
- Address correspondence to: Dr. Paul J. Lockhart, Murdoch Childrens Research Institute, The Royal Children's Hospital, Flemington Road Parkville, Victoria 3052, Australia. E-mail:
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Anderson AE, Galko MJ. Rapid clearance of epigenetic protein reporters from wound edge cells in Drosophila larvae does not depend on the JNK or PDGFR/VEGFR signaling pathways. ACTA ACUST UNITED AC 2014; 1:11-25. [PMID: 25114797 PMCID: PMC4126263 DOI: 10.1002/reg2.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The drastic cellular changes required for epidermal cells to dedifferentiate and become motile during wound closure are accompanied by changes in gene transcription, suggesting corresponding alterations in chromatin. However, the epigenetic changes that underlie wound-induced transcriptional programs remain poorly understood partly because a comprehensive study of epigenetic factor expression during wound healing has not been practical. To determine which chromatin modifying factors might contribute to wound healing, we screened publicly available fluorescently-tagged reporter lines in Drosophila for altered expression at the wound periphery during healing. Thirteen reporters tagging seven different proteins showed strongly diminished expression at the wound edge. Three downregulated proteins, Osa, Kismet, and Spt6, are generally associated with active chromatin, while four others, Sin3A, Sap130, Mi-2, and Mip120, are associated with repressed chromatin. In all cases reporter down regulation was independent of the Jun N-terminal Kinase and Pvr pathways, suggesting that novel signals control reporter clearance. Taken together, our results suggest that clearance of chromatin modifying factors may enable wound edge cells to rapidly and comprehensively change their transcriptional state following tissue damage.
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Affiliation(s)
- Aimee E Anderson
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Unit 1000, 1515 Holcombe Boulevard, Houston, TX 77030, USA
| | - Michael J Galko
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Unit 1000, 1515 Holcombe Boulevard, Houston, TX 77030, USA ; Genes & Development Graduate Program, The University of Texas MD Anderson Cancer Center, Unit 1000, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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10
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Janssens DH, Komori H, Grbac D, Chen K, Koe CT, Wang H, Lee CY. Earmuff restricts progenitor cell potential by attenuating the competence to respond to self-renewal factors. Development 2014; 141:1036-46. [PMID: 24550111 DOI: 10.1242/dev.106534] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Despite expressing stem cell self-renewal factors, intermediate progenitor cells possess restricted developmental potential, which allows them to give rise exclusively to differentiated progeny rather than stem cell progeny. Failure to restrict the developmental potential can allow intermediate progenitor cells to revert into aberrant stem cells that might contribute to tumorigenesis. Insight into stable restriction of the developmental potential in intermediate progenitor cells could improve our understanding of the development and growth of tumors, but the mechanisms involved remain largely unknown. Intermediate neural progenitors (INPs), generated by type II neural stem cells (neuroblasts) in fly larval brains, provide an in vivo model for investigating the mechanisms that stably restrict the developmental potential of intermediate progenitor cells. Here, we report that the transcriptional repressor protein Earmuff (Erm) functions temporally after Brain tumor (Brat) and Numb to restrict the developmental potential of uncommitted (immature) INPs. Consistently, endogenous Erm is detected in immature INPs but undetectable in INPs. Erm-dependent restriction of the developmental potential in immature INPs leads to attenuated competence to respond to all known neuroblast self-renewal factors in INPs. We also identified that the BAP chromatin-remodeling complex probably functions cooperatively with Erm to restrict the developmental potential of immature INPs. Together, these data led us to conclude that the Erm-BAP-dependent mechanism stably restricts the developmental potential of immature INPs by attenuating their genomic responses to stem cell self-renewal factors. We propose that restriction of developmental potential by the Erm-BAP-dependent mechanism functionally distinguishes intermediate progenitor cells from stem cells, ensuring the generation of differentiated cells and preventing the formation of progenitor cell-derived tumor-initiating stem cells.
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Affiliation(s)
- Derek H Janssens
- Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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11
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Eroglu E, Burkard TR, Jiang Y, Saini N, Homem CCF, Reichert H, Knoblich JA. SWI/SNF complex prevents lineage reversion and induces temporal patterning in neural stem cells. Cell 2014; 156:1259-1273. [PMID: 24630726 DOI: 10.1016/j.cell.2014.01.053] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 11/11/2013] [Accepted: 01/16/2014] [Indexed: 12/22/2022]
Abstract
Members of the SWI/SNF chromatin-remodeling complex are among the most frequently mutated genes in human cancer, but how they suppress tumorigenesis is currently unclear. Here, we use Drosophila neuroblasts to demonstrate that the SWI/SNF component Osa (ARID1) prevents tumorigenesis by ensuring correct lineage progression in stem cell lineages. We show that Osa induces a transcriptional program in the transit-amplifying population that initiates temporal patterning, limits self-renewal, and prevents dedifferentiation. We identify the Prdm protein Hamlet as a key component of this program. Hamlet is directly induced by Osa and regulates the progression of progenitors through distinct transcriptional states to limit the number of transit-amplifying divisions. Our data provide a mechanistic explanation for the widespread tumor suppressor activity of SWI/SNF. Because the Hamlet homologs Evi1 and Prdm16 are frequently mutated in cancer, this mechanism could well be conserved in human stem cell lineages. PAPERCLIP:
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Affiliation(s)
- Elif Eroglu
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Thomas R Burkard
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Yanrui Jiang
- Biozentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Nidhi Saini
- Biozentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Catarina C F Homem
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Heinrich Reichert
- Biozentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Juergen A Knoblich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria.
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12
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Rogers WA, Grover S, Stringer SJ, Parks J, Rebeiz M, Williams TM. A survey of the trans-regulatory landscape for Drosophila melanogaster abdominal pigmentation. Dev Biol 2014; 385:417-32. [DOI: 10.1016/j.ydbio.2013.11.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/07/2013] [Accepted: 11/05/2013] [Indexed: 10/26/2022]
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13
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Zeng X, Lin X, Hou SX. The Osa-containing SWI/SNF chromatin-remodeling complex regulates stem cell commitment in the adult Drosophila intestine. Development 2013; 140:3532-40. [PMID: 23942514 DOI: 10.1242/dev.096891] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The proportion of stem cells versus differentiated progeny is well balanced to maintain tissue homeostasis, which in turn depends on the balance of the different signaling pathways involved in stem cell self-renewal versus lineage-specific differentiation. In a screen for genes that regulate cell lineage determination in the posterior midgut, we identified that the Osa-containing SWI/SNF (Brahma) chromatin-remodeling complex regulates Drosophila midgut homeostasis. Mutations in subunits of the Osa-containing complex result in intestinal stem cell (ISC) expansion as well as enteroendocrine (EE) cell reduction. We further demonstrated that Osa regulates ISC self-renewal and differentiation into enterocytes by elaborating Notch signaling, and ISC commitment to differentiation into EE cells by regulating the expression of Asense, an EE cell fate determinant. Our data uncover a unique mechanism whereby the commitment of stem cells to discrete lineages is coordinately regulated by chromatin-remodeling factors.
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Affiliation(s)
- Xiankun Zeng
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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14
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Jin Y, Xu J, Yin MX, Lu Y, Hu L, Li P, Zhang P, Yuan Z, Ho MS, Ji H, Zhao Y, Zhang L. Brahma is essential for Drosophila intestinal stem cell proliferation and regulated by Hippo signaling. eLife 2013; 2:e00999. [PMID: 24137538 PMCID: PMC3796317 DOI: 10.7554/elife.00999] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/08/2013] [Indexed: 11/13/2022] Open
Abstract
Chromatin remodeling processes are among the most important regulatory mechanisms in controlling cell proliferation and regeneration. Drosophila intestinal stem cells (ISCs) exhibit self-renewal potentials, maintain tissue homeostasis, and serve as an excellent model for studying cell growth and regeneration. In this study, we show that Brahma (Brm) chromatin-remodeling complex is required for ISC proliferation and damage-induced midgut regeneration in a lineage-specific manner. ISCs and enteroblasts exhibit high levels of Brm proteins; and without Brm, ISC proliferation and differentiation are impaired. Importantly, the Brm complex participates in ISC proliferation induced by the Scalloped-Yorkie transcriptional complex and that the Hippo (Hpo) signaling pathway directly restricted ISC proliferation by regulating Brm protein levels by inducing caspase-dependent cleavage of Brm. The cleavage resistant form of Brm protein promoted ISC proliferation. Our findings highlighted the importance of Hpo signaling in regulating epigenetic components such as Brm to control downstream transcription and hence ISC proliferation. DOI:http://dx.doi.org/10.7554/eLife.00999.001.
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Affiliation(s)
- Yunyun Jin
- State Key Laboratory of Cell Biology , Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai , China
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15
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Identification of genes underlying hypoxia tolerance in Drosophila by a P-element screen. G3-GENES GENOMES GENETICS 2012; 2:1169-78. [PMID: 23050227 PMCID: PMC3464109 DOI: 10.1534/g3.112.003681] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/23/2012] [Indexed: 01/17/2023]
Abstract
Hypoxia occurs in physiologic conditions (e.g. high altitude) or during pathologic states (e.g. ischemia). Our research is focused on understanding the molecular mechanisms that lead to adaptation and survival or injury to hypoxic stress using Drosophila as a model system. To identify genes involved in hypoxia tolerance, we screened the P-SUP P-element insertion lines available for all the chromosomes of Drosophila. We screened for the eclosion rates of embryos developing under 5% O(2) condition and the number of adult flies surviving one week after eclosion in the same hypoxic environment. Out of 2187 lines (covering ~1870 genes) screened, 44 P-element lines representing 44 individual genes had significantly higher eclosion rates (i.e. >70%) than those of the controls (i.e. ~7-8%) under hypoxia. The molecular function of these candidate genes ranged from cell cycle regulation, DNA or protein binding, GTP binding activity, and transcriptional regulators. In addition, based on pathway analysis, we found these genes are involved in multiple pathways, such as Notch, Wnt, Jnk, and Hedgehog. Particularly, we found that 20 out of the 44 candidate genes are linked to Notch signaling pathway, strongly suggesting that this pathway is essential for hypoxia tolerance in flies. By employing the UAS/RNAi-Gal4 system, we discovered that genes such as osa (linked to Wnt and Notch pathways) and lqf (Notch regulator) play an important role in survival and development under hypoxia in Drosophila. Based on these results and our previous studies, we conclude that hypoxia tolerance is a polygenic trait including the Notch pathway.
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16
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Enjolras C, Thomas J, Chhin B, Cortier E, Duteyrat JL, Soulavie F, Kernan MJ, Laurençon A, Durand B. Drosophila chibby is required for basal body formation and ciliogenesis but not for Wg signaling. ACTA ACUST UNITED AC 2012; 197:313-25. [PMID: 22508513 PMCID: PMC3328381 DOI: 10.1083/jcb.201109148] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In contrast to vertebrate CBY, which functions in WNT signaling, Drosophila CBY is essential for normal basal body structure and function but dispensable for Wg signaling. Centriole-to–basal body conversion, a complex process essential for ciliogenesis, involves the progressive addition of specific proteins to centrioles. CHIBBY (CBY) is a coiled-coil domain protein first described as interacting with β-catenin and involved in Wg-Int (WNT) signaling. We found that, in Drosophila melanogaster, CBY was exclusively expressed in cells that require functional basal bodies, i.e., sensory neurons and male germ cells. CBY was associated with the basal body transition zone (TZ) in these two cell types. Inactivation of cby led to defects in sensory transduction and in spermatogenesis. Loss of CBY resulted in altered ciliary trafficking into neuronal cilia, irregular deposition of proteins on spermatocyte basal bodies, and, consequently, distorted axonemal assembly. Importantly, cby1/1 flies did not show Wingless signaling defects. Hence, CBY is essential for normal basal body structure and function in Drosophila, potentially through effects on the TZ. The function of CBY in WNT signaling in vertebrates has either been acquired during vertebrate evolution or lost in Drosophila.
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Affiliation(s)
- Camille Enjolras
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR 5534, Université Claude Bernard Lyon 1, Villeurbanne, Lyon F69622, France
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17
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Nowak SJ, Aihara H, Gonzalez K, Nibu Y, Baylies MK. Akirin links twist-regulated transcription with the Brahma chromatin remodeling complex during embryogenesis. PLoS Genet 2012; 8:e1002547. [PMID: 22396663 PMCID: PMC3291577 DOI: 10.1371/journal.pgen.1002547] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 01/04/2012] [Indexed: 11/19/2022] Open
Abstract
The activities of developmentally critical transcription factors are regulated via interactions with cofactors. Such interactions influence transcription factor activity either directly through protein–protein interactions or indirectly by altering the local chromatin environment. Using a yeast double-interaction screen, we identified a highly conserved nuclear protein, Akirin, as a novel cofactor of the key Drosophila melanogaster mesoderm and muscle transcription factor Twist. We find that Akirin interacts genetically and physically with Twist to facilitate expression of some, but not all, Twist-regulated genes during embryonic myogenesis. akirin mutant embryos have muscle defects consistent with altered regulation of a subset of Twist-regulated genes. To regulate transcription, Akirin colocalizes and genetically interacts with subunits of the Brahma SWI/SNF-class chromatin remodeling complex. Our results suggest that, mechanistically, Akirin mediates a novel connection between Twist and a chromatin remodeling complex to facilitate changes in the chromatin environment, leading to the optimal expression of some Twist-regulated genes during Drosophila myogenesis. We propose that this Akirin-mediated link between transcription factors and the Brahma complex represents a novel paradigm for providing tissue and target specificity for transcription factor interactions with the chromatin remodeling machinery. The proper development of the diverse array of cell types in an organism depends upon the induction and repression of specific genes at particular times and places. This gene regulation requires both the activity of tissue-specific transcriptional regulators and the modulation of the chromatin environment. To date, a complete picture of the interplay between these two processes remains unclear. To address this, we examined the activity of the evolutionarily conserved transcription factor Twist during embryogenesis of Drosophila melanogaster. While Twist has multiple activities and roles during development, a direct link between Twist and chromatin remodeling is unknown. We identified a highly conserved protein, Akirin, as a link between Twist and chromatin remodeling factors. Akirin is required for optimal expression of a Twist-dependent target during muscle development via interactions with the Drosophila SWI/SNF chromatin remodeling complex. Interestingly, Akirin is not required for activation of all Twist-dependent enhancers, suggesting that Akirin refines Twist activity outputs and that different Twist-dependent targets have different requirements for chromatin remodeling during development. Our data further suggests that Akirin similarly links the SWI/SNF chromatin remodeling complex with other transcription factors during development. This work has important ramifications for understanding both normal development and diseases such as cancer.
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Affiliation(s)
- Scott J. Nowak
- Program in Developmental Biology, Sloan Kettering Institute, New York, New York, United States of America
| | - Hitoshi Aihara
- Cell and Developmental Biology, Weill Cornell Medical College, New York, New York, United States of America
| | - Katie Gonzalez
- Weill Cornell Graduate School of Biomedical Sciences, Cornell University, New York, New York, United States of America
| | - Yutaka Nibu
- Cell and Developmental Biology, Weill Cornell Medical College, New York, New York, United States of America
- Weill Cornell Graduate School of Biomedical Sciences, Cornell University, New York, New York, United States of America
| | - Mary K. Baylies
- Program in Developmental Biology, Sloan Kettering Institute, New York, New York, United States of America
- Weill Cornell Graduate School of Biomedical Sciences, Cornell University, New York, New York, United States of America
- * E-mail:
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18
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Waldholm J, Wang Z, Brodin D, Tyagi A, Yu S, Theopold U, Farrants AKÖ, Visa N. SWI/SNF regulates the alternative processing of a specific subset of pre-mRNAs in Drosophila melanogaster. BMC Mol Biol 2011; 12:46. [PMID: 22047075 PMCID: PMC3221629 DOI: 10.1186/1471-2199-12-46] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/02/2011] [Indexed: 12/25/2022] Open
Abstract
Background The SWI/SNF chromatin remodeling factors have the ability to remodel nucleosomes and play essential roles in key developmental processes. SWI/SNF complexes contain one subunit with ATPase activity, which in Drosophila melanogaster is called Brahma (Brm). The regulatory activities of SWI/SNF have been attributed to its influence on chromatin structure and transcription regulation, but recent observations have revealed that the levels of Brm affect the relative abundances of transcripts that are formed by alternative splicing and/or polyadenylation of the same pre-mRNA. Results We have investigated whether the function of Brm in pre-mRNA processing in Drosophila melanogaster is mediated by Brm alone or by the SWI/SNF complex. We have analyzed the effects of depleting individual SWI/SNF subunits on pre-mRNA processing throughout the genome, and we have identified a subset of transcripts that are affected by depletion of the SWI/SNF core subunits Brm, Snr1 or Mor. The fact that depletion of different subunits targets a subset of common transcripts suggests that the SWI/SNF complex is responsible for the effects observed on pre-mRNA processing when knocking down Brm. We have also depleted Brm in larvae and we have shown that the levels of SWI/SNF affect the pre-mRNA processing outcome in vivo. Conclusions We have shown that SWI/SNF can modulate alternative pre-mRNA processing, not only in cultured cells but also in vivo. The effect is restricted to and specific for a subset of transcripts. Our results provide novel insights into the mechanisms by which SWI/SNF regulates transcript diversity and proteomic diversity in higher eukaryotes.
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Affiliation(s)
- Johan Waldholm
- Department of Molecular Biology and Functional Genomics, Stockholm University, SE-10691 Stockholm, Sweden
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19
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Target genes of the largest human SWI/SNF complex subunit control cell growth. Biochem J 2011; 434:83-92. [PMID: 21118156 DOI: 10.1042/bj20101358] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The largest subunit of the mammalian SWI/SNF-A or BAF (BRG1-associated factor) chromatin-remodelling complex is encoded by two related cDNAs hOsa1/BAF250a and hOsa2/BAF250b that are unique to the BAF complex and absent in the related PBAF (Polybromo BAF). hOsa/BAF250 has been shown to interact with transcriptional activators and bind to DNA suggesting that it acts to target the remodelling complex to chromatin. To better understand the functions of hOsa2, we established inducible stable HeLa cell lines over-expressing FLAG-hOsa2 or a derivative lacking the ARID (AT-rich interactive domain) DNA-binding domain. Immunopurification of complexes containing hOsa2 that was followed by mass spectrometry and immunoblotting demonstrated the presence of BRG1 and known BAFs, but not hOsa1 or hBRM. Deletion of the ARID did not compromise the integrity of the complex. Induction of hOsa2 expression caused impaired cell growth and accumulation of cells in the G0/G1 cell cycle phase. Elevated levels of the p53 and p21 proteins were detected in these cells while c-Myc mRNA and protein levels were found to decrease. Chromatin immunoprecipitation and reporter assays suggested that hOsa2 had a direct effect on c-myc and p21 promoter activity. Thus hOsa2 plays an important role in controlling genes regulating the cell cycle.
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20
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Curtis BJ, Zraly CB, Marenda DR, Dingwall AK. Histone lysine demethylases function as co-repressors of SWI/SNF remodeling activities during Drosophila wing development. Dev Biol 2010; 350:534-47. [PMID: 21146519 DOI: 10.1016/j.ydbio.2010.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 11/08/2010] [Accepted: 12/02/2010] [Indexed: 11/20/2022]
Abstract
The conserved SWI/SNF chromatin remodeling complex uses the energy from ATP hydrolysis to alter local chromatin environments through disrupting DNA-histone contacts. These alterations influence transcription activation, as well as repression. The Drosophila SWI/SNF counterpart, known as the Brahma or Brm complex, has been shown to have an essential role in regulating the proper expression of many developmentally important genes, including those required for eye and wing tissue morphogenesis. A temperature sensitive mutation in one of the core complex subunits, SNR1 (SNF5/INI1/SMARCB1), results in reproducible wing patterning phenotypes that can be dominantly enhanced and suppressed by extragenic mutations. SNR1 functions as a regulatory subunit to modulate chromatin remodeling activities of the Brahma complex on target genes, including both activation and repression. To help identify gene targets and cofactors of the Brahma complex, we took advantage of the weak dominant nature of the snr1(E1) mutation to carry out an unbiased genetic modifier screen. Using a set of overlapping chromosomal deficiencies that removed the majority of the Drosophila genome, we looked for genes that when heterozygous would function to either enhance or suppress the snr1(E1) wing pattern phenotype. Among potential targets of the Brahma complex, we identified components of the Notch, EGFR and DPP signaling pathways important for wing development. Mutations in genes encoding histone demethylase enzymes were identified as cofactors of Brahma complex function. In addition, we found that the Lysine Specific Demethylase 1 gene (lsd1) was important for the proper cell type-specific development of wing patterning.
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Affiliation(s)
- Brenda J Curtis
- Graduate Program in Molecular and Cellular Biochemistry, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
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21
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Quijano JC, Stinchfield MJ, Zerlanko B, Gibbens YY, Takaesu NT, Hyman-Walsh C, Wotton D, Newfeld SJ. The Sno oncogene antagonizes Wingless signaling during wing development in Drosophila. PLoS One 2010; 5:e11619. [PMID: 20661280 PMCID: PMC2905394 DOI: 10.1371/journal.pone.0011619] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 06/15/2010] [Indexed: 11/18/2022] Open
Abstract
The Sno oncogene (Snoo or dSno in Drosophila) is a highly conserved protein and a well-established antagonist of Transforming Growth Factor-β signaling in overexpression assays. However, analyses of Sno mutants in flies and mice have proven enigmatic in revealing developmental roles for Sno proteins. Thus, to identify developmental roles for dSno we first reconciled conflicting data on the lethality of dSno mutations. Then we conducted analyses of wing development in dSno loss of function genotypes. These studies revealed ectopic margin bristles and ectopic campaniform sensilla in the anterior compartment of the wing blade suggesting that dSno functions to antagonize Wingless (Wg) signaling. A subsequent series of gain of function analyses yielded the opposite phenotype (loss of bristles and sensilla) and further suggested that dSno antagonizes Wg signal transduction in target cells. To date Sno family proteins have not been reported to influence the Wg pathway during development in any species. Overall our data suggest that dSno functions as a tissue-specific component of the Wg signaling pathway with modest antagonistic activity under normal conditions but capable of blocking significant levels of extraneous Wg, a role that may be conserved in vertebrates.
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Affiliation(s)
- Janine C. Quijano
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Michael J. Stinchfield
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Brad Zerlanko
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia, United States of America
| | - Ying Y. Gibbens
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Norma T. Takaesu
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Cathy Hyman-Walsh
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia, United States of America
| | - David Wotton
- Department of Biochemistry and Molecular Genetics, and Center for Cell Signaling, University of Virginia, Charlottesville, Virginia, United States of America
| | - Stuart J. Newfeld
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- * E-mail:
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22
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Bap170, a subunit of the Drosophila PBAP chromatin remodeling complex, negatively regulates the EGFR signaling. Genetics 2010; 186:167-81. [PMID: 20551433 DOI: 10.1534/genetics.110.118695] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BAP and PBAP constitute the two different forms of the Drosophila melanogaster Brahma chromatin remodelers. A common multisubunit core, containing the Brahma ATPase, can associate either with Osa to form the BAP complex or with Bap170, Bap180, and Sayp to constitute the PBAP complex. Although required for many biological processes, recent genetic analyses revealed that one role of the BAP complex during Drosophila wing development is the proper regulation of EGFR target genes. Here, we show that Bap170, a distinctive subunit of the PBAP complex, participates instead in the negative regulation of EGFR signaling. In adults, loss of Bap170 generates phenotypes similar to the defects induced by hyperactivation of the EGFR pathway, such as overrecruitment of cone and photoreceptor cells and formation extra veins. In genetic interactions, bap170 mutations suppress the loss of veins and photoreceptors caused by mutations affecting the activity of the EGFR pathway. Our results suggest a dual requirement of the PBAP complex: for transcriptional repression of rhomboid and for efficient expression of argos. Interestingly, genetic evidence also indicates that Bap170-mediated repression of rho is inhibited by EGFR signaling, suggesting a scenario of mutual antagonism between EGFR signaling and PBAP function.
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23
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The chromatin-remodeling protein Osa interacts with CyclinE in Drosophila eye imaginal discs. Genetics 2009; 184:731-44. [PMID: 20008573 DOI: 10.1534/genetics.109.109967] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Coordinating cell proliferation and differentiation is essential during organogenesis. In Drosophila, the photoreceptor, pigment, and support cells of the eye are specified in an orchestrated wave as the morphogenetic furrow passes across the eye imaginal disc. Cells anterior of the furrow are not yet differentiated and remain mitotically active, while most cells in the furrow arrest at G(1) and adopt specific ommatidial fates. We used microarray expression analysis to monitor changes in transcription at the furrow and identified genes whose expression correlates with either proliferation or fate specification. Some of these are members of the Polycomb and Trithorax families that encode epigenetic regulators. Osa is one; it associates with components of the Drosophila SWI/SNF chromatin-remodeling complex. Our studies of this Trithorax factor in eye development implicate Osa as a regulator of the cell cycle: Osa overexpression caused a small-eye phenotype, a reduced number of M- and S-phase cells in eye imaginal discs, and a delay in morphogenetic furrow progression. In addition, we present evidence that Osa interacts genetically and biochemically with CyclinE. Our results suggest a dual mechanism of Osa function in transcriptional regulation and cell cycle control.
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24
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Terriente-Félix A, de Celis JF. Osa, a subunit of the BAP chromatin-remodelling complex, participates in the regulation of gene expression in response to EGFR signalling in the Drosophila wing. Dev Biol 2009; 329:350-61. [PMID: 19306864 DOI: 10.1016/j.ydbio.2009.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 03/05/2009] [Accepted: 03/12/2009] [Indexed: 01/27/2023]
Abstract
Gene expression is regulated in part by protein complexes containing ATP-dependent chromatin-remodelling factors of the SWI/SNF family. In Drosophila there is only one SWI/SNF protein, named Brahma, which forms the catalytic subunit of two complexes composed of different proteins. The protein Osa defines the BAP complex, and the proteins Polybromo and Bap170 are only present in the complex named PBAP. In this work we have analysed the functional requirements of Osa during Drosophila wing development, and found that osa is needed for cell growth and survival in the wing imaginal disc, and for the correct patterning of sensory organs, veins and the wing margin. Other members of the BAP complex, such as Snr1, Bap55, Mor and Brm, also share these functions of Osa. We focused on the requirement of Osa during the formation of the wing veins. Genetic interactions between osa alleles and mutations affecting the activity of the EGFR pathway suggest that one aspect of Osa is intimately related to the response to EGFR activity. Thus, loss of osa and EGFR signalling results in similar wing vein phenotypes, and osa alleles enhance the loss of veins caused by reduced EGFR activity. In addition, Osa is required for the expression of several targets of EGFR signalling, such as Delta, rhomboid and argos. We suggest that one role of Osa and Brm in the wing is to establish a chromatin environment in the regulatory regions of EGFR target genes, making them available for both activators and repressors and facilitating transcription in response to EGFR signalling.
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Affiliation(s)
- Ana Terriente-Félix
- Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
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25
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Identification of novel regulators of atonal expression in the developing Drosophila retina. Genetics 2008; 180:2095-110. [PMID: 18832354 DOI: 10.1534/genetics.108.093302] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Atonal is a Drosophila proneural protein required for the proper formation of the R8 photoreceptor cell, the founding photoreceptor cell in the developing retina. Proper expression and refinement of the Atonal protein is essential for the proper formation of the Drosophila adult eye. In vertebrates, expression of transcription factors orthologous to Drosophila Atonal (MATH5/Atoh7, XATH5, and ATH5) and their progressive restriction are also involved in specifying the retinal ganglion cell, the founding neural cell type in the mammalian retina. Thus, identifying factors that are involved in regulating the expression of Atonal during development are important to fully understand how retinal neurogenesis is accomplished. We have performed a chemical mutagenesis screen for autosomal dominant enhancers of a loss-of-function atonal eye phenotype. We report here the identification of five genes required for proper Atonal expression, three of which are novel regulators of Atonal expression in the Drosophila retina. We characterize the role of the daughterless, kismet, and roughened eye genes on atonal transcriptional regulation in the developing retina and show that each gene regulates atonal transcription differently within the context of retinal development. Our results provide additional insights into the regulation of Atonal expression in the developing Drosophila retina.
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26
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Two subunits specific to the PBAP chromatin remodeling complex have distinct and redundant functions during drosophila development. Mol Cell Biol 2008; 28:5238-50. [PMID: 18573871 DOI: 10.1128/mcb.00747-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Chromatin remodeling complexes control the availability of DNA binding sites to transcriptional regulators. Two distinct conserved forms of the SWI/SNF class of complexes are characterized by the presence of specific accessory subunits. In Drosophila, the core Brahma complex associates either with Osa to form the BAP complex or with Bap170 and Bap180 to form the PBAP complex. osa mutations reproduce only a subset of the developmental phenotypes caused by mutations in subunits of the core complex. To test whether the PBAP complex performs the remaining functions, we generated mutations in bap170 and bap180. Surprisingly, we found that Bap180 is not essential for viability, although it is required in ovarian follicle cells for normal eggshell development. Bap170 is necessary to stabilize the Bap180 protein, but a mutant form that retains this function is sufficient for both survival and fertility. The two subunits act redundantly to allow metamorphosis; using gene expression profiling of bap170 bap180 double mutants, we found that the PBAP complex regulates genes involved in tissue remodeling and immune system function. Finally, we generated mutants lacking Bap170, Bap180, and Osa in the germ line to demonstrate that the core Brahma complex can function in oogenesis without any of these accessory subunits.
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27
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Nakamura K, Ida H, Yamaguchi M. Transcriptional regulation of the Drosophila moira and osa genes by the DREF pathway. Nucleic Acids Res 2008; 36:3905-15. [PMID: 18511465 PMCID: PMC2475616 DOI: 10.1093/nar/gkn291] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The DNA replication-related element binding factor (DREF) plays an important role in regulation of cell proliferation in Drosophila, binding to DRE and activating transcription of genes carrying this element in their promoter regions. Overexpression of DREF in eye imaginal discs induces a rough eye phenotype in adults, which can be suppressed by half dose reduction of the osa or moira (mor) genes encoding subunits of the BRM complex. This ATP-dependent chromatin remodeling complex is known to control gene expression and the cell cycle. In the 5' flanking regions of the osa and mor genes, DRE and DRE-like sequences exist which contribute to their promoter activities. Expression levels and promoter activities of osa and mor are decreased in DREF knockdown cells and our results in vitro and in cultured cells indicate that transcription of osa and mor is regulated by the DRE/DREF regulatory pathway. In addition, mRNA levels of other BRM complex subunits and a target gene, string/cdc25, were found to be decreased by knockdown of DREF. These results indicate that DREF is involved in regulation of the BRM complex and thereby the cell cycle.
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Affiliation(s)
- Kumi Nakamura
- Department of Applied Biology and Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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28
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The transcriptional coactivator SAYP is a trithorax group signature subunit of the PBAP chromatin remodeling complex. Mol Cell Biol 2008; 28:2920-9. [PMID: 18299390 DOI: 10.1128/mcb.02217-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SWI/SNF ATP-dependent chromatin remodeling complexes (remodelers) perform critical functions in eukaryotic gene expression control. BAP and PBAP are the fly representatives of the two evolutionarily conserved major subclasses of SWI/SNF remodelers. Both complexes share seven core subunits, including the Brahma ATPase, but differ in a few signature subunits; POLYBROMO and BAP170 specify PBAP, whereas OSA defines BAP. Here, we show that the transcriptional coactivator and PHD finger protein SAYP is a novel PBAP subunit. Biochemical analysis established that SAYP is tightly associated with PBAP but absent from BAP. SAYP, POLYBROMO, and BAP170 display an intimately overlapping distribution on larval salivary gland polytene chromosomes. Genome-wide expression analysis revealed that SAYP is critical for PBAP-dependent transcription. SAYP is required for normal development and interacts genetically with core- and PBAP-selective subunits. Genetic analysis suggested that, like BAP, PBAP also counteracts Polycomb silencing. SAYP appears to be a key architectural component required for the integrity and association of the PBAP-specific module. We conclude that SAYP is a signature subunit that plays a major role in the functional specificity of the PBAP holoenzyme.
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Garin G, Zibara K, Aguilar F, Lo M, Hurlstone A, Poston R, Mcgregor JL. 6A3-5/Osa2 is an early activated gene implicated in the control of vascular smooth muscle cell functions. J Biomed Biotechnol 2007; 2006:97287. [PMID: 17489020 PMCID: PMC1698265 DOI: 10.1155/jbb/2006/97287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vascular smooth muscle cells (VSMC) growth plays a key role in the pathophysiology of vascular diseases. However, the molecular mechanisms controlling gene transcription in VSMC remain poorly understood. We previously identified, by differential display, a new gene (6A3-5) overexpressed in proliferating rat VSMC. In this study, we have cloned the full-length cDNA by screening a rat foetal brain cDNA library and investigated its functions. The 6A3-5 protein shows 4 putative conserved functional motifs: a DNA binding domain called ARID (AT-rich interaction domain), two recently described motifs (Osa Homology Domain), and a nuclear localization signal. The deduced protein sequence was observed to be 85% identical to the recently described human Osa2 gene. Immunolabelling, using an anti-6A3-5/Osa2 monoclonal antibody, showed a nuclear localization of the 6A3-5/Osa2 protein. In addition, PDGF upregulated 6A3-5/Osa2 expression at both the transcript and protein levels in a dose and time-dependent fashion. The pattern of upregulation by PDGF was reminiscent of the early responsive gene c-fos. The PDGF-induced upregulation of 6A3-5/Osa2 and proliferation of VSMC were significantly inhibited in a dose and sequence-dependent fashion by an antisense, but not by sense, scrambled or mismatched oligonucleotides directed against 6A3-5/Osa2. In VSMC of aortas derived from hypertensive (LH) rats, 6A3-5/Osa2 is overexpressed as compared to that in normotensive (LL) rats. The 6A3-5/Osa2-gene expression is downregulated by an ACE inhibitor and upregulated by exogenous AngiotensinII in LH rats. In summary, these results indicate that 6A3-5/Osa2 is an early activated gene that belongs to a new family of proteins involved in the control of VSMC growth.
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Affiliation(s)
- Gwenaele Garin
- INSERM XR331, Faculté of Médicine Laënnec, Lyon 69372, France
- Genomics and Atherothrombosis, Thrombosis Research Institute, London SW3 6LR, UK
| | - Kazem Zibara
- INSERM XR331, Faculté of Médicine Laënnec, Lyon 69372, France
- Genomics and Atherothrombosis, Thrombosis Research Institute, London SW3 6LR, UK
| | - Frederick Aguilar
- Département de Physiologie et Pharmacologie Clinique, Faculté de Pharmacie, Université Lyon 1, Lyon, France
| | - Ming Lo
- Département de Physiologie et Pharmacologie Clinique, Faculté de Pharmacie, Université Lyon 1, Lyon, France
| | - Adam Hurlstone
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - Robin Poston
- Center for Cardiovascular Biology and Medicine, King's College, University of London, UK
| | - John L. Mcgregor
- INSERM XR331, Faculté of Médicine Laënnec, Lyon 69372, France
- Genomics and Atherothrombosis, Thrombosis Research Institute, London SW3 6LR, UK
- Center for Cardiovascular Biology and Medicine, King's College, University of London, UK
- *John L. Mcgregor:
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Doroquez DB, Rebay I. Signal integration during development: mechanisms of EGFR and Notch pathway function and cross-talk. Crit Rev Biochem Mol Biol 2007; 41:339-85. [PMID: 17092823 DOI: 10.1080/10409230600914344] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metazoan development relies on a highly regulated network of interactions between conserved signal transduction pathways to coordinate all aspects of cell fate specification, differentiation, and growth. In this review, we discuss the intricate interplay between the epidermal growth factor receptor (EGFR; Drosophila EGFR/DER) and the Notch signaling pathways as a paradigm for signal integration during development. First, we describe the current state of understanding of the molecular architecture of the EGFR and Notch signaling pathways that has resulted from synergistic studies in vertebrate, invertebrate, and cultured cell model systems. Then, focusing specifically on the Drosophila eye, we discuss how cooperative, sequential, and antagonistic relationships between these pathways mediate the spatially and temporally regulated processes that generate this sensory organ. The common themes underlying the coordination of the EGFR and Notch pathways appear to be broadly conserved and should, therefore, be directly applicable to elucidating mechanisms of information integration and signaling specificity in vertebrate systems.
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Affiliation(s)
- David B Doroquez
- Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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Parker DS, Blauwkamp T, Cadigan KM. Wnt/β‐catenin‐mediated transcriptional regulation. WNT SIGNALING IN EMBRYONIC DEVELOPMENT 2007. [DOI: 10.1016/s1574-3349(06)17001-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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D'Costa A, Reifegerste R, Sierra S, Moses K. The Drosophila ramshackle gene encodes a chromatin-associated protein required for cell morphology in the developing eye. Mech Dev 2006; 123:591-604. [PMID: 16904300 DOI: 10.1016/j.mod.2006.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2005] [Revised: 06/26/2006] [Accepted: 06/28/2006] [Indexed: 12/21/2022]
Abstract
We have identified ramshackle (ram) as a dominant suppressor of hedgehog loss-of-function in the developing Drosophila eye. We have characterized the gene and it encodes a double bromodomain protein with eight WD40 repeats. The Ram protein is localized predominantly to polytene chromosome interbands and is required for the transcription of some genes. ram is an essential gene and null mutants die during larval life. In the developing retina, ram mutant cells have morphological defects including disrupted apical junctions, disorganized actin cytoskeletons and mislocalized nuclei, which are followed by delays in cell-cycle transitions and the expression of differentiation markers. ram is a conserved gene: its vertebrate homolog (WDR9), which lies in Down's Syndrome Critical region 2 (DCR2) is also known to be associated with Brahma-Related-Gene 1 (BRG1).
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Affiliation(s)
- Allison D'Costa
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322-3030, USA
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Mathew D, Ataman B, Chen J, Zhang Y, Cumberledge S, Budnik V. Wingless signaling at synapses is through cleavage and nuclear import of receptor DFrizzled2. Science 2005; 310:1344-7. [PMID: 16311339 PMCID: PMC3535279 DOI: 10.1126/science.1117051] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Wingless secretion provides pivotal signals during development by activating transcription of target genes. At Drosophila synapses, Wingless is secreted from presynaptic terminals and is required for synaptic growth and differentiation. Wingless binds the seven-pass transmembrane DFrizzled2 receptor, but the ensuing events at synapses are not known. We show that DFrizzled2 is endocytosed from the postsynaptic membrane and transported to the nucleus. The C terminus of DFrizzled2 is cleaved and translocated into the nucleus; the N-terminal region remains just outside the nucleus. Translocation of DFrizzled2-C into the nucleus, but not its cleavage and transport, depends on Wingless signaling. We conclude that, at synapses, Wingless signal transduction occurs through the nuclear localization of DFrizzled2-C for potential transcriptional regulation of synapse development.
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Affiliation(s)
- Dennis Mathew
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Bulent Ataman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jinyun Chen
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Yali Zhang
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Susan Cumberledge
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Vivian Budnik
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- To whom correspondence should be addressed:
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Zibara K, Garin G, McGregor JL. Identification, structural, and functional characterization of a new early gene (6A3-5, 7 kb): implication in the proliferation and differentiation of smooth muscle cells. J Biomed Biotechnol 2005; 2005:254-70. [PMID: 16192684 PMCID: PMC1224700 DOI: 10.1155/jbb.2005.254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Arterial smooth muscle cells (SMCs) play a major role in atherosclerosis and restenosis. Differential display was used to compare transcription profiles of synthetic SMCs to proliferating rat cultured SMC line. An isolated cDNA band (6A3-5) was shown by northern (7 kb) to be upregulated in the proliferating cell line. A rat tissue northern showed differential expression of this gene in different tissues. Using 5' RACE and screening of a rat brain library, part of the cDNA was cloned and sequenced (5.4 kb). Sequence searches showed important similarities with a new family of transcription factors, bearing ARID motifs. A polyclonal antibody was raised and showed a protein band of 175 kd, which is localized intracellularly. We also showed that 6A3-5 is upregulated in dedifferentiated SMC (P9) in comparison to contractile SMC ex vivo (P0). This work describes cloning, structural, and functional characterization of a new early gene involved in SMC phenotype modulation.
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Affiliation(s)
- Kazem Zibara
- INSERM XR331, Faculty of Medicine RTH Laënnec, 69372 Lyon, France
- *Kazem Zibara:
| | - Gwenaële Garin
- Genomics and Atherothrombosis Laboratory, Thrombosis Research Institute, London
SW3 6LR, UK
| | - John L. McGregor
- Center for Cardiovascular Biology and Medicine, King's College, University of London,
London WC2R 2LS, UK
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Vanolst L, Fromental-Ramain C, Ramain P. Toutatis, a TIP5-related protein, positively regulates Pannier function during Drosophila neural development. Development 2005; 132:4327-38. [PMID: 16141224 DOI: 10.1242/dev.02014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The GATA factor Pannier (Pnr) activates proneural expression through binding to a remote enhancer of the achaete-scute (ac-sc) complex. Chip associates both with Pnr and with the (Ac-Sc)-Daughterless heterodimer bound to the ac-sc promoters to give a proneural complex that facilitates enhancer-promoter communication during development. Using a yeast two-hybrid screening, we have identified Toutatis (Tou), which physically interacts with both Pnr and Chip. Loss-of-function and gain-of-function experiments indicate that Tou cooperates with Pnr and Chip during neural development. Tou shares functional domains with chromatin remodelling proteins, including TIP5 (termination factor TTFI-interacting protein 5) of NoRC (nucleolar remodelling complex), which mediates repression of RNA polymerase 1 transcription. In contrast, Tou acts positively to activate proneural gene expression. Moreover, we show that Iswi associates with Tou, Pnr and Chip, and is also required during Pnr-driven neural development. The results suggest that Tou and Iswi may belong to a complex that directly regulates the activity of Pnr and Chip during enhancer-promoter communication, possibly through chromatin remodelling.
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Affiliation(s)
- Luc Vanolst
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Developmental Biology, CNRS/INSERM/ULP, Boite Postale 10142, 67404 Illkirch Cedex, France
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36
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Callery EM, Smith JC, Thomsen GH. The ARID domain protein dril1 is necessary for TGF(beta) signaling in Xenopus embryos. Dev Biol 2005; 278:542-59. [PMID: 15680369 DOI: 10.1016/j.ydbio.2004.11.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 10/30/2004] [Accepted: 11/11/2004] [Indexed: 11/18/2022]
Abstract
ARID domain proteins are members of a highly conserved family involved in chromatin remodeling and cell-fate determination. Dril1 is the founding member of the ARID family and is involved in developmental processes in both Drosophila and Caenorhabditis elegans. We describe the first embryological characterization of this gene in chordates. Dril1 mRNA expression is spatiotemporally regulated and is detected in the involuting mesoderm during gastrulation. Inhibition of dril1 by either a morpholino or an engrailed repressor-dril1 DNA binding domain fusion construct inhibits gastrulation and perturbs induction of the zygotic mesodermal marker Xbra and the organizer markers chordin, noggin, and Xlim1. Xenopus tropicalis dril1 morphants also exhibit impaired gastrulation and axial deficiencies, which can be rescued by coinjection of Xenopus laevis dril1 mRNA. Loss of dril1 inhibits the response of animal caps to activin and secondary axis induction by smad2. Dril1 depletion in animal caps prevents both the smad2-mediated induction of dorsal mesodermal and endodermal markers and the induction of ventral mesoderm by smad1. Mesoderm induction by eFGF is uninhibited in dril1 morphant caps, reflecting pathway specificity for dril1. These experiments identify dril1 as a novel regulator of TGF(beta) signaling and a vital component of mesodermal patterning and embryonic morphogenesis.
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Affiliation(s)
- Elizabeth M Callery
- Department of Biochemistry and Cell Biology and Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5215, USA.
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37
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Kankel MW, Duncan DM, Duncan I. A screen for genes that interact with the Drosophila pair-rule segmentation gene fushi tarazu. Genetics 2005; 168:161-80. [PMID: 15454535 PMCID: PMC1448101 DOI: 10.1534/genetics.104.027250] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The pair-rule gene fushi tarazu (ftz) of Drosophila is expressed at the blastoderm stage in seven stripes that serve to define the even-numbered parasegments. ftz encodes a DNA-binding homeodomain protein and is known to regulate genes of the segment polarity, homeotic, and pair-rule classes. Despite intensive analysis in a number of laboratories, how ftz is regulated and how it controls its targets are still poorly understood. To help understand these processes, we conducted a screen to identify dominant mutations that enhance the lethality of a ftz temperature-sensitive mutant. Twenty-six enhancers were isolated, which define 21 genes. All but one of the mutations recovered show a maternal effect in their interaction with ftz. Three of the enhancers proved to be alleles of the known ftz protein cofactor gene ftz-f1, demonstrating the efficacy of the screen. Four enhancers are alleles of Atrophin (Atro), the Drosophila homolog of the human gene responsible for the neurodegenerative disease dentatorubral-pallidoluysian atrophy. Embryos from Atro mutant germ-line mothers lack the even-numbered (ftz-dependent) engrailed stripes and show strong ftz-like segmentation defects. These defects likely result from a reduction in Even-skipped (Eve) repression ability, as Atro has been shown to function as a corepressor for Eve. In this study, we present evidence that Atro is also a member of the trithorax group (trxG) of Hox gene regulators. Atro appears to be particularly closely related in function to the trxG gene osa, which encodes a component of the brahma chromatin remodeling complex. One additional gene was identified that causes pair-rule segmentation defects in embryos from homozygous mutant germ-line mothers. The single allele of this gene, called bek, also causes nuclear abnormalities similar to those caused by alleles of the Trithorax-like gene, which encodes the GAGA factor.
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Affiliation(s)
- Mark W Kankel
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA
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38
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Milán M, Pham TT, Cohen SM. Osa modulates the expression of Apterous target genes in the Drosophila wing. Mech Dev 2005; 121:491-7. [PMID: 15147766 DOI: 10.1016/j.mod.2004.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Revised: 03/05/2004] [Accepted: 03/05/2004] [Indexed: 11/29/2022]
Abstract
The establishment of the dorsal-ventral axis of the Drosophila wing depends on the activity of the LIM-homeodomain protein Apterous. Apterous activity depends on the formation of a higher order complex with its cofactor Chip to induce the expression of its target genes. Apterous activity levels are modulated during development by dLMO. Expression of dLMO in the Drosophila wing is regulated by two distinct Chip dependent mechanisms. Early in development, Chip bridges two molecules of Apterous to induce expression of dLMO in the dorsal compartment. Later in development, Chip, independently of Apterous, is required for expression of dLMO in the wing pouch. We have conducted a modular P-element based EP (enhancer/promoter) misexpression screen to look for genes involved in Apterous activity. We have found Osa, a member of the Brahma chromatin-remodeling complex, as a positive modulator of Apterous activity in the Drosophila wing. Osa mediates activation of some Apterous target genes and repression of others, including dLMO. Osa has been shown to bind Chip. We propose that Chip recruits Osa to the Apterous target genes, thus mediating activation or repression of their expression.
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Affiliation(s)
- Marco Milán
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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39
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Luschnig S, Moussian B, Krauss J, Desjeux I, Perkovic J, Nüsslein-Volhard C. An F1 genetic screen for maternal-effect mutations affecting embryonic pattern formation in Drosophila melanogaster. Genetics 2005; 167:325-42. [PMID: 15166158 PMCID: PMC1470860 DOI: 10.1534/genetics.167.1.325] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Large-scale screens for female-sterile mutations have revealed genes required maternally for establishment of the body axes in the Drosophila embryo. Although it is likely that the majority of components involved in axis formation have been identified by this approach, certain genes have escaped detection. This may be due to (1) incomplete saturation of the screens for female-sterile mutations and (2) genes with essential functions in zygotic development that mutate to lethality, precluding their identification as female-sterile mutations. To overcome these limitations, we performed a genetic mosaic screen aimed at identifying new maternal genes required for early embryonic patterning, including zygotically required ones. Using the Flp-FRT technique and a visible germline clone marker, we developed a system that allows efficient screening for maternal-effect phenotypes after only one generation of breeding, rather than after the three generations required for classic female-sterile screens. We identified 232 mutants showing various defects in embryonic pattern or morphogenesis. The mutants were ordered into 10 different phenotypic classes. A total of 174 mutants were assigned to 86 complementation groups with two alleles on average. Mutations in 45 complementation groups represent most previously known maternal genes, while 41 complementation groups represent new loci, including several involved in dorsoventral, anterior-posterior, and terminal patterning.
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Affiliation(s)
- Stefan Luschnig
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, D-72076 Tübingen, Germany.
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40
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Janody F, Lee JD, Jahren N, Hazelett DJ, Benlali A, Miura GI, Draskovic I, Treisman JE. A mosaic genetic screen reveals distinct roles for trithorax and polycomb group genes in Drosophila eye development. Genetics 2004; 166:187-200. [PMID: 15020417 PMCID: PMC1470713 DOI: 10.1534/genetics.166.1.187] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The wave of differentiation that traverses the Drosophila eye disc requires rapid transitions in gene expression that are controlled by a number of signaling molecules also required in other developmental processes. We have used a mosaic genetic screen to systematically identify autosomal genes required for the normal pattern of photoreceptor differentiation, independent of their requirements for viability. In addition to genes known to be important for eye development and to known and novel components of the Hedgehog, Decapentaplegic, Wingless, Epidermal growth factor receptor, and Notch signaling pathways, we identified several members of the Polycomb and trithorax classes of genes encoding general transcriptional regulators. Mutations in these genes disrupt the transitions between zones along the anterior-posterior axis of the eye disc that express different combinations of transcription factors. Different trithorax group genes have very different mutant phenotypes, indicating that target genes differ in their requirements for chromatin remodeling, histone modification, and coactivation factors.
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Affiliation(s)
- Florence Janody
- Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
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41
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Mohrmann L, Langenberg K, Krijgsveld J, Kal AJ, Heck AJR, Verrijzer CP. Differential targeting of two distinct SWI/SNF-related Drosophila chromatin-remodeling complexes. Mol Cell Biol 2004; 24:3077-88. [PMID: 15060132 PMCID: PMC381637 DOI: 10.1128/mcb.24.8.3077-3088.2004] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The SWI/SNF family of ATP-dependent chromatin-remodeling factors plays a central role in eukaryotic transcriptional regulation. In yeast and human cells, two subclasses have been recognized: one comprises yeast SWI/SNF and human BAF, and the other includes yeast RSC and human PBAF. Therefore, it was puzzling that Drosophila appeared to contain only a single SWI/SNF-type remodeler, the Brahma (BRM) complex. Here, we report the identification of two novel BRM complex-associated proteins: Drosophila Polybromo and BAP170, a conserved protein not described previously. Biochemical analysis established that Drosophila contains two distinct BRM complexes: (i) the BAP complex, defined by the presence of OSA and the absence of Polybromo and BAP170, and (ii) the PBAP complex, containing Polybromo and BAP170 but lacking OSA. Determination of the genome-wide distributions of OSA and Polybromo on larval salivary gland polytene chromosomes revealed that BAP and PBAP display overlapping but distinct distribution patterns. Both complexes associate predominantly with regions of open, hyperacetylated chromatin but are largely excluded from Polycomb-bound repressive chromatin. We conclude that, like yeast and human cells, Drosophila cells express two distinct subclasses of the SWI/SNF family. Our results support a close reciprocity of chromatin regulation by ATP-dependent remodelers and histone-modifying enzymes.
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Affiliation(s)
- Lisette Mohrmann
- Gene Regulation Laboratory, Centre for Biomedical Genetics, Department of Molecular and Cell Biology, Leiden University Medical Centre, 2300 RA Leiden, The Netherlands
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42
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Marenda DR, Zraly CB, Dingwall AK. The Drosophila Brahma (SWI/SNF) chromatin remodeling complex exhibits cell-type specific activation and repression functions. Dev Biol 2004; 267:279-93. [PMID: 15013794 DOI: 10.1016/j.ydbio.2003.10.040] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Accepted: 10/25/2003] [Indexed: 11/21/2022]
Abstract
The Brahma (Brm) complex of Drosophila melanogaster is a SWI/SNF-related chromatin remodeling complex required to correctly maintain proper states of gene expression through ATP-dependent effects on chromatin structure. The SWI/SNF complexes are comprised of 8-11 stable components, even though the SWI2/SNF2 (BRM, BRG1, hBRM) ATPase subunit alone is partially sufficient to carry out chromatin remodeling in vitro. The remaining subunits are required for stable complex assembly and/or proper promoter targeting in vivo. Our data reveals that SNR1 (SNF5-Related-1), a highly conserved subunit of the Brm complex, is required to restrict complex activity during the development of wing vein and intervein cells, illustrating a functional requirement for SNR1 in modifying whole complex activation functions. Specifically, we found that snr1 and brm exhibited opposite mutant phenotypes in the wing and differential misregulation of genes required for vein and intervein cell development, including rhomboid, decapentaplegic, thick veins, and blistered, suggesting possible regulatory targets for the Brm complex in vivo. Our genetic results suggest a novel mechanism for SWI/SNF-mediated gene repression that relies on the function of a 'core' subunit to block or shield BRM (SWI2/SNF2) activity in specific cells. The SNR1-mediated repression is dependent on cooperation with histone deacetylases (HDAC) and physical associations with NET, a localized vein repressor.
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Affiliation(s)
- Daniel R Marenda
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
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43
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Nixon JC, Rajaiya JB, Ayers N, Evetts S, Webb CF. The transcription factor, Bright, is not expressed in all human B lymphocyte subpopulations. Cell Immunol 2004; 228:42-53. [PMID: 15203319 DOI: 10.1016/j.cellimm.2004.03.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Accepted: 03/21/2004] [Indexed: 01/23/2023]
Abstract
Bright is an ARID family transcription factor that increases immunoglobulin heavy chain transcription. In the mouse, Bright expression is tightly regulated and B cell-restricted and the Bright protein associates with Bruton's tyrosine kinase (Btk), the defective enzyme in X-linked immunodeficiency. Human X-linked agammaglobulinemia results from defects in Btk and leads to early blocks in B lymphocyte development. Because so little is known about human Bright, we sought to determine where human Bright is expressed in normal B cell differentiation and whether it also forms complexes with Btk. Although human and mouse Bright exhibited similar expression patterns in normal B cells, many human transformed B cell lines did not express Bright protein. However, the human protein bound prototypic Bright DNA-binding motifs and, like mouse Bright, was capable of associating with Btk. These data suggest potentially important similarities exist in Bright expression and activity in human and mouse B lymphocytes.
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Affiliation(s)
- Jamee C Nixon
- Department of Microbiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Abstract
Cardiac development is a complex biological process requiring the integration of cell specification, differentiation, migration, proliferation, and morphogenesis. Although significant progress has been made recently in understanding the molecular basis of cardiac development, mechanisms of transcriptional control of cardiac development remain largely unknown. In search for the developmentally important genes, the jumonji gene (jmj) was identified by gene trap technology and characterized as a critical nuclear factor for mouse embryonic development. Jmj has been shown to play important roles in cardiovascular development, neural tube fusion process, hematopoiesis, and liver development in mouse embryos. The amino acid sequence of the JUMONJI protein (JMJ) reveals that JMJ belongs to the AT-rich interaction domain transcription factor family and more recently has been described as a member of the JMJ transcription factor family. Here, we review the roles of jmj in multiple organ development with a focus on cardiovascular development in mice.
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Affiliation(s)
- Jooyoung Jung
- Department of Anatomy, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA
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45
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Sedkov Y, Cho E, Petruk S, Cherbas L, Smith ST, Jones RS, Cherbas P, Canaani E, Jaynes JB, Mazo A. Methylation at lysine 4 of histone H3 in ecdysone-dependent development of Drosophila. Nature 2003; 426:78-83. [PMID: 14603321 PMCID: PMC2743927 DOI: 10.1038/nature02080] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2003] [Accepted: 09/15/2003] [Indexed: 11/08/2022]
Abstract
Steroid hormones fulfil important functions in animal development. In Drosophila, ecdysone triggers moulting and metamorphosis through its effects on gene expression. Ecdysone works by binding to a nuclear receptor, EcR, which heterodimerizes with the retinoid X receptor homologue Ultraspiracle. Both partners are required for binding to ligand or DNA. Like most DNA-binding transcription factors, nuclear receptors activate or repress gene expression by recruiting co-regulators, some of which function as chromatin-modifying complexes. For example, p160 class coactivators associate with histone acetyltransferases and arginine histone methyltransferases. The Trithorax-related gene of Drosophila encodes the SET domain protein TRR. Here we report that TRR is a histone methyltransferases capable of trimethylating lysine 4 of histone H3 (H3-K4). trr acts upstream of hedgehog (hh) in progression of the morphogenetic furrow, and is required for retinal differentiation. Mutations in trr interact in eye development with EcR, and EcR and TRR can be co-immunoprecipitated on ecdysone treatment. TRR, EcR and trimethylated H3-K4 are detected at the ecdysone-inducible promoters of hh and BR-C in cultured cells, and H3-K4 trimethylation at these promoters is decreased in embryos lacking a functional copy of trr. We propose that TRR functions as a coactivator of EcR by altering the chromatin structure at ecdysone-responsive promoters.
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Affiliation(s)
- Yurii Sedkov
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Salvaing J, Lopez A, Boivin A, Deutsch JS, Peronnet F. The Drosophila Corto protein interacts with Polycomb-group proteins and the GAGA factor. Nucleic Acids Res 2003; 31:2873-82. [PMID: 12771214 PMCID: PMC156716 DOI: 10.1093/nar/gkg381] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In Drosophila, PcG complexes provide heritable transcriptional silencing of target genes. Among them, the ESC/E(Z) complex is thought to play a role in the initiation of silencing whereas other complexes such as the PRC1 complex are thought to maintain it. PcG complexes are thought to be recruited to DNA through interaction with DNA binding proteins such as the GAGA factor, but no direct interactions between the constituents of PcG complexes and the GAGA factor have been reported so far. The Drosophila corto gene interacts with E(z) as well as with genes encoding members of maintenance complexes, suggesting that it could play a role in the transition between the initiation and maintenance of PcG silencing. Moreover, corto also interacts genetically with Trl, which encodes the GAGA factor, suggesting that it may serve as a mediator in recruiting PcG complexes. Here, we show that Corto bears a chromo domain and we provide evidence for in vivo association of Corto with ESC and with PC in embryos. Moreover, we show by GST pull-down and two-hybrid experiments that Corto binds to E(Z), ESC, PH, SCM and GAGA and co-localizes with these proteins on a few sites on polytene chromosomes. These results reinforce the idea that Corto plays a role in PcG silencing, perhaps by confering target specificity.
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Affiliation(s)
- Juliette Salvaing
- UMR 7622-Biologie du Développement, CNRS et Université Paris VI, 9 Quai Saint-Bernard, F-75252 Paris cedex 05, France
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Wang W. The SWI/SNF family of ATP-dependent chromatin remodelers: similar mechanisms for diverse functions. Curr Top Microbiol Immunol 2003; 274:143-69. [PMID: 12596907 DOI: 10.1007/978-3-642-55747-7_6] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The SWI/SNF family of complexes utilizes the energy of ATP hydrolysis to remodel chromatin structures, thereby allowing transcription factors to gain access to DNA. Recent studies suggest that these remodelers also participate in other DNA metabolic reactions such as replication and viral integration, and even in control of cell growth and tumor suppression. The SWI/SNF remodelers can be classified into at least two distinct subfamilies: one includes human BAF (also known as hSWI/SNF-A) and yeast SWI/SNF; the other comprises human PBAF (hSWI/SNF-B) and yeast RSC. Although both types of complexes have similar subunit composition and chromatin remodeling activity in vitro, they cannot replace each other during transcription mediated by specific activators. Thus, each remodeler probably works with a specific set of activators during gene activation. The availability of distinct types of remodelers can allow cells to regulate expression of a specific group of genes by modulating the activity of corresponding remodelers.
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Affiliation(s)
- W Wang
- Laboratory of Genetics, National Institute on Aging, National Institute of Health, 333 Cassell Drive, TRIAD Center Room 4000, Baltimore, MD 21224, USA.
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Heitzler P, Vanolst L, Biryukova I, Ramain P. Enhancer-promoter communication mediated by Chip during Pannier-driven proneural patterning is regulated by Osa. Genes Dev 2003; 17:591-6. [PMID: 12629041 PMCID: PMC196006 DOI: 10.1101/gad.255703] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The GATA factor Pannier activates proneural achaete/scute (ac/sc) expression during development of the sensory organs of Drosophila through enhancer binding. Chip bridges Pannier with the (Ac/Sc)-Daughterless heterodimers bound to the promoter and facilitates the enhancer-promoter communication required for proneural development. We show here that this communication is regulated by Osa, which is recruited by Pannier and Chip. Osa belongs to Brahma chromatin remodeling complexes and we show that Osa negatively regulates ac/sc. Consequently, Pannier and Chip also play an essential role during repression of proneural gene expression. Our study suggests that altering chromatin structure is essential for regulation of enhancer-promoter communication.
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Affiliation(s)
- Pascal Heitzler
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 67404 Illkirch Cedex, Strasbourg, France.
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Gutiérrez L, Zurita M, Kennison JA, Vázquez M. The Drosophila trithorax group gene tonalli (tna) interacts genetically with the Brahma remodeling complex and encodes an SP-RING finger protein. Development 2003; 130:343-54. [PMID: 12466201 DOI: 10.1242/dev.00222] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The trithorax group genes are required for positive regulation of homeotic gene function. The trithorax group gene brahma encodes a SWI2/SNF2 family ATPase that is a catalytic subunit of the Brm chromatin-remodeling complex. We identified the tonalli (tna) gene in Drosophila by genetic interactions with brahma. tna mutations suppress Polycomb phenotypes and tna is required for the proper expressions of the Antennapedia, Ultrabithorax and Sex combs reduced homeotic genes. The tna gene encodes at least two proteins, a large isoform (TnaA) and a short isoform (TnaB). The TnaA protein has an SP-RING Zn finger, conserved in proteins from organisms ranging from yeast to human and thought to be involved in the sumoylation of protein substrates. Besides the SP-RING finger, the TnaA protein also has extended homology with other eukaryotic proteins, including human proteins. We show that tna mutations also interact with mutations in additional subunits of the Brm complex, with mutations in subunits of the Mediator complex, and with mutations of the SWI2/SNF2 family ATPase gene kismet. We propose that Tna is involved in postranslational modification of transcription complexes.
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Affiliation(s)
- Luis Gutiérrez
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, UNAM, Cuernavaca, Morelos 62250, México
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Abstract
The existence and function of actin in the nucleus has been hotly debated for forty years. Recently, beta-actin was found to be a component of mammalian SWI/SNF-like BAF chromatin remodeling complexes and still more recently other SWI/SNF-related chromatin remodeling complexes in yeast, flies, and man. Although the function of actin in these chromatin remodeling complexes is only starting to be explored, the fact that actin is one of the most regulated proteins in the cell suggests that control of nuclear actin may be a critical regulatory point in the control of chromatin remodeling. Actin rapidly shuttles between the nucleus and the cytoplasm offering additional sites and modes of regulation. In addition, actin-related proteins (Arps) are also components of these chromatin remodeling complexes and have been implicated in transcriptional control in yeast. The observation that the BAF chromatin remodeling complex in which actin was originally identified, is also a human tumor suppressor complex necessary for the actions of the retinoblastoma protein indicates that the study of nuclear actin is likely to contribute to understanding cell growth control.
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Affiliation(s)
- Ivan A Olave
- Department of Developmental Biology and Department of Pathology, Howard Hughes Medical Institute at Stanford University, Stanford, California 94305, USA.
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