201
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Wang S, Jones KA. CK2 controls the recruitment of Wnt regulators to target genes in vivo. Curr Biol 2007; 16:2239-44. [PMID: 17113388 DOI: 10.1016/j.cub.2006.09.034] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 09/15/2006] [Accepted: 09/19/2006] [Indexed: 02/08/2023]
Abstract
Nuclear beta-catenin is a transcriptional coactivator of LEF-1/TCF DNA-binding proteins in the Wnt/Wg signaling pathway. Casein Kinase 2 (CK2), a positive regulator of Wnt signaling, is present in beta-catenin complexes and activated in Wnt-signaling cells. We show here that CK2 enhances beta-catenin:LEF-1 transactivation in vivo and in vitro and that beta-catenin and CK2 cycle on and off the DNA in an alternating manner with the TLE1 corepressor at Wnt target genes. Interestingly, CK2 phosphorylates hLEF-1 directly and stimulates binding and transactivation of beta-catenin:LEF-1 complexes on chromatin templates in vitro. In vitro, CK2 phosphorylation of hLEF-1 strongly enhances its affinity for beta-catenin and reduces its affinity for TLE1. MALDI-TOF mass spectrometry (MS) identified two CK2 phosphorylation sites (S42, S61) within the amino terminus of hLEF-1, and mutation of these sites reduced binding to beta-catenin in vitro and transactivation in vivo. Remarkably, treatment of cells with TBB, a pharmaceutical inhibitor of CK2, blocked the recruitment and cycling of beta-catenin and TLE1 at Wnt target genes in vivo. Taken together, these data indicate that CK2 is required for the assembly and cycling of Wnt-enhancer complexes in vivo.
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Affiliation(s)
- Song Wang
- Regulatory Biology Laboratory, The Salk Institute, 10010 N. Torrey Pines Road, La Jolla, California 92037, USA
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202
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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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203
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White JA, Heasman J. Maternal control of pattern formation inXenopus laevis. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2007; 310:73-84. [PMID: 17219372 DOI: 10.1002/jez.b.21153] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We review the essential role of maternal factors in pattern formation for Xenopus laevis, focusing on VegT, Vg1, and Wnt11. Results from loss of function experiments demonstrate a clear requirement for these genes in germ layer specification, dorsal-ventral axis formation, and convergence extension. We also discuss these genes in the broader context of metazoan development, exploring whether and how their functions in the X. laevis model organism may or may not be conserved in other species. Wnt11 signaling in particular provides a classic example where understanding context in development is crucial to understanding function. Genomic sequencing, gene expression, and functional screening data that are becoming available in more species are providing invaluable aid to decoding and modeling signaling pathways. More work is needed to develop a comprehensive catalog of the Wnt signaling, T-box, and TGF-beta genes in metazoans both near and far in evolutionary distance. We finally discuss some specific experimental and modeling efforts that will be needed to understand the behavior of these signaling networks in vivo so that we can interpret these critical pathways in an evolutionary framework.
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Affiliation(s)
- Jody A White
- Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, Ohio 45229-3039, USA.
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204
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Ahrens CH, Wagner U, Rehrauer HK, Türker C, Schlapbach R. Current challenges and approaches for the synergistic use of systems biology data in the scientific community. EXS 2007; 97:277-307. [PMID: 17432272 DOI: 10.1007/978-3-7643-7439-6_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Today's rapid development and broad application of high-throughput analytical technologies are transforming biological research and provide an amount of data and analytical opportunities to understand the fundamentals of biological processes undreamt of in past years. To fully exploit the potential of the large amount of data, scientists must be able to understand and interpret the information in an integrative manner. While the sheer data volume and heterogeneity of technical platforms within each discipline already poses a significant challenge, the heterogeneity of platforms and data formats across disciplines makes the integrative management, analysis, and interpretation of data a significantly more difficult task. This challenge thus lies at the heart of systems biology, which aims at a quantitative understanding of biological systems to the extent that systemic features can be predicted. In this chapter, we discuss several key issues that need to be addressed in order to put an integrated systems biology data analysis and mining within reach.
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Affiliation(s)
- Christian H Ahrens
- Functional Genomics Center Zurich, Winterthurerstrasse 190, Y32H66, CH-8057 Zurich, Switzerland.
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205
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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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206
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Lyne R, Smith R, Rutherford K, Wakeling M, Varley A, Guillier F, Janssens H, Ji W, Mclaren P, North P, Rana D, Riley T, Sullivan J, Watkins X, Woodbridge M, Lilley K, Russell S, Ashburner M, Mizuguchi K, Micklem G. FlyMine: an integrated database for Drosophila and Anopheles genomics. Genome Biol 2007; 8:R129. [PMID: 17615057 PMCID: PMC2323218 DOI: 10.1186/gb-2007-8-7-r129] [Citation(s) in RCA: 269] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 03/06/2007] [Accepted: 06/05/2007] [Indexed: 01/29/2023] Open
Abstract
FlyMine is a data warehouse that addresses one of the important challenges of modern biology: how to integrate and make use of the diversity and volume of current biological data. Its main focus is genomic and proteomics data for Drosophila and other insects. It provides web access to integrated data at a number of different levels, from simple browsing to construction of complex queries, which can be executed on either single items or lists.
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Affiliation(s)
- Rachel Lyne
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Richard Smith
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Kim Rutherford
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Matthew Wakeling
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Andrew Varley
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Francois Guillier
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Hilde Janssens
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Wenyan Ji
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Peter Mclaren
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Philip North
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Debashis Rana
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Tom Riley
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Julie Sullivan
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Xavier Watkins
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Mark Woodbridge
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Kathryn Lilley
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Steve Russell
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Michael Ashburner
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Kenji Mizuguchi
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
- Cambridge Computational Biology Institute, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 OWA, UK
- National Institute of Biomedical Innovation 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Gos Micklem
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
- Cambridge Computational Biology Institute, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 OWA, UK
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207
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Kourtidis A, Eifert C, Conklin DS. RNAi applications in target validation. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2007:1-21. [PMID: 17249494 DOI: 10.1007/978-3-540-31339-7_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The emergence of systems biology is certain to transform the identification and validation of therapeutic targets in modern drug discovery. A relatively recent systems biology approach is functional genomics, which identifies the molecular mechanisms responsible for a specific phenotype by interrogating the activity of all of an organism's genes. Initially undertaken in model organisms such as Caenorhabditis elegans, Saccharomyces cerevisiae, and Drosophila melanogaster, functional genomics has now moved into the realm of mammalian cells both in vitro and in vivo due to the development of RNA interference. RNA interference is a conserved biological process that has evolved to specifically and efficiently silence genes. Genome-wide screens using RNA interference have proven powerful in elucidating components of functionally related pathways and have therefore become integral for the development of new and improved therapeutic targets. This article provides an overview of many of the systems biology approaches taken, using RNA interference, in order to demonstrate how it may be used today for drug discovery and tomorrow as a targeted therapy.
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Affiliation(s)
- A Kourtidis
- Department of Biomedical Sciences, Gen"NY"Sis Center for Excellence Cancer Genomics, University at Albany, Rensselaer, NY 12144, USA
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208
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Abstract
The fruitfly, Drosophila melanogaster, has been of central importance in analysing the mechanics of cellular processes. Classic forward genetic screens in the fly have identified many of the genes that define critical cell signaling pathways, for example. Our understanding of the Wnt pathway, in particular, has benefited from the many advantages that the fly offers as a model system. Here, I review the history of these discoveries and highlight the utility of the fly in dissecting the molecular workings of Wnt signal transduction.
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Affiliation(s)
- A Bejsovec
- Department of Biology, Duke University, Durham, NC 27708-1000, USA.
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209
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Croce JC, Wu SY, Byrum C, Xu R, Duloquin L, Wikramanayake AH, Gache C, McClay DR. A genome-wide survey of the evolutionarily conserved Wnt pathways in the sea urchin Strongylocentrotus purpuratus. Dev Biol 2006; 300:121-31. [PMID: 17069790 PMCID: PMC1780136 DOI: 10.1016/j.ydbio.2006.08.045] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 08/18/2006] [Accepted: 08/19/2006] [Indexed: 02/07/2023]
Abstract
The Wnt pathways are evolutionarily well-conserved signal transduction pathways that are known to play important roles in all Metazoans investigated to date. Here, we examine the Wnt pathway genes and target genes present in the genome of the echinoderm Strongylocentrotus purpuratus. Analysis of the Wnt genes revealed that eleven of the thirteen reported Wnt subfamilies are represented in sea urchin, with the intriguing identification of a Wnt-A ortholog thought to be absent in deuterostomes. A phylogenetic study of the Frizzled proteins, the Wnt receptors, performed throughout the animal kingdom showed that not all Frizzled subfamilies were present in the metazoan common ancestor, e.g. Fz3/6 emerged later during evolution. Using sequence analysis, orthologs of the vast majority of the cellular machinery involved in transducing the three types of Wnt pathways were found in the sea urchin genome. Furthermore, of about one hundred target genes identified in other organisms, more than half have clear echinoderm orthologs. Thus, these analyses produce new inputs in the evolutionary history of the Wnt genes in an animal occupying a position that offers great insights into the basal properties of deuterostomes.
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Affiliation(s)
- Jenifer C. Croce
- Developmental, Molecular, and Cellular Biology Group, Duke University, Durham, NC, USA
| | - Shu-Yu Wu
- Developmental, Molecular, and Cellular Biology Group, Duke University, Durham, NC, USA
| | - Christine Byrum
- Developmental, Molecular, and Cellular Biology Group, Duke University, Durham, NC, USA
- Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Ronghui Xu
- Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii
| | - Louise Duloquin
- Unité de Biologie du Développement, UMR 7009, CNRS, Université Pierre et Marie Curie, Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
| | | | - Christian Gache
- Unité de Biologie du Développement, UMR 7009, CNRS, Université Pierre et Marie Curie, Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
| | - David R. McClay
- Developmental, Molecular, and Cellular Biology Group, Duke University, Durham, NC, USA
- * Corresponding author. Duke University, DCMB Group, LSRC Bldg Rm. B359A, Research Drive, Durham, NC, 27708. Tel: +1-919-613-8188. Fax: +1-919-613-8177. * E-mail address:
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210
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Kikuchi A, Yamamoto H, Kishida S. Multiplicity of the interactions of Wnt proteins and their receptors. Cell Signal 2006; 19:659-71. [PMID: 17188462 DOI: 10.1016/j.cellsig.2006.11.001] [Citation(s) in RCA: 207] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 11/07/2006] [Indexed: 02/07/2023]
Abstract
Wnts are secreted proteins that are essential for a wide array of developmental and physiological processes. They signal across the plasma membranes by interacting with serpentine receptors of the Frizzled (Fz) family and members of the low-density-lipoprotein receptor-related protein (LRP) family. Recent advances in the Wnt signaling field have revealed that Wnt-unrelated proteins activate or suppress Wnt signaling by binding to Fzs or LRP5/6 and that atypical receptor tyrosine kinases mediate Wnt signaling independently of Fz and/or function as a Fz co-receptor. This review highlights recent progress in our understanding of the multiplicity of Wnts and their receptors. We discuss how the interaction between the ligands and receptors activate distinct intracellular signaling pathways. We also discuss how intracellular trafficking of Wnt signaling components can regulate the sensitivity of cells to Wnts.
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Affiliation(s)
- Akira Kikuchi
- Department of Biochemistry, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Hiroshima, Japan.
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211
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Sick S, Reinker S, Timmer J, Schlake T. WNT and DKK determine hair follicle spacing through a reaction-diffusion mechanism. Science 2006; 314:1447-50. [PMID: 17082421 DOI: 10.1126/science.1130088] [Citation(s) in RCA: 389] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mathematical reaction-diffusion models have been suggested to describe formation of animal pigmentation patterns and distribution of epidermal appendages. However, the crucial signals and in vivo mechanisms are still elusive. Here we identify WNT and its inhibitor DKK as primary determinants of murine hair follicle spacing, using a combined experimental and computational modeling approach. Transgenic DKK overexpression reduces overall appendage density. Moderate suppression of endogenous WNT signaling forces follicles to form clusters during an otherwise normal morphogenetic program. These results confirm predictions of a WNT/DKK-specific mathematical model and provide in vivo corroboration of the reaction-diffusion mechanism for epidermal appendage formation.
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Affiliation(s)
- Stefanie Sick
- Max-Planck Institute of Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany
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212
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Friedman A, Perrimon N. A functional RNAi screen for regulators of receptor tyrosine kinase and ERK signalling. Nature 2006; 444:230-4. [PMID: 17086199 DOI: 10.1038/nature05280] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 09/22/2006] [Indexed: 11/08/2022]
Abstract
Receptor tyrosine kinase (RTK) signalling through extracellular-signal-regulated kinases (ERKs) has pivotal roles during metazoan development, underlying processes as diverse as fate determination, differentiation, proliferation, survival, migration and growth. Abnormal RTK/ERK signalling has been extensively documented to contribute to developmental disorders and disease, most notably in oncogenic transformation by mutant RTKs or downstream pathway components such as Ras and Raf. Although the core RTK/ERK signalling cassette has been characterized by decades of research using mammalian cell culture and forward genetic screens in model organisms, signal propagation through this pathway is probably regulated by a larger network of moderate, context-specific proteins. The genes encoding these proteins may not have been discovered through traditional screens owing, in particular, to the requirement for visible phenotypes. To obtain a global view of RTK/ERK signalling, we performed an unbiased, RNA interference (RNAi), genome-wide, high-throughput screen in Drosophila cells using a novel, quantitative, cellular assay monitoring ERK activation. Here we show that ERK pathway output integrates a wide array of conserved cellular processes. Further analysis of selected components-in multiple cell types with different RTK ligands and oncogenic stimuli-validates and classifies 331 pathway regulators. The relevance of these genes is highlighted by our isolation of a Ste20-like kinase and a PPM-family phosphatase that seem to regulate RTK/ERK signalling in vivo and in mammalian cells. Novel regulators that modulate specific pathway outputs may be selective targets for drug discovery.
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Affiliation(s)
- Adam Friedman
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
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213
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Fewell GD, Schmitt K. Vector-based RNAi approaches for stable, inducible and genome-wide screens. Drug Discov Today 2006; 11:975-82. [PMID: 17055406 DOI: 10.1016/j.drudis.2006.09.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 08/03/2006] [Accepted: 09/11/2006] [Indexed: 01/21/2023]
Abstract
RNA interference (RNAi) has revolutionized the study of biology and offers numerous applications in basic biology as well as in drug discovery research. Since the discovery of RNAi, several tools have been developed to enable loss-of-function studies in mammalian systems. The efficacy of RNAi is dependent on specific and versatile RNAi triggers that have evolved to enable transient, stable and in-vivo applications. Recently developed genome-wide short hairpin RNA (shRNA) and microRNA-adapted short hairpin RNA (shRNAmir) libraries incorporate advances in shRNA design and molecular 'barcodes' to enable more complex RNAi screens and the opportunity to progress to more complex genetics in whole animals.
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Affiliation(s)
- Gwen D Fewell
- Open Biosystems Inc. 6705 Odyssey Drive, Huntsville, Al 35806, USA.
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214
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Perrimon N, Friedman A, Mathey-Prevot B, Eggert US. Drug-target identification in Drosophila cells: combining high-throughout RNAi and small-molecule screens. Drug Discov Today 2006; 12:28-33. [PMID: 17198970 DOI: 10.1016/j.drudis.2006.10.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 09/04/2006] [Accepted: 10/16/2006] [Indexed: 10/24/2022]
Abstract
RNA interference (RNAi) and small-molecule approaches are synergistic on multiple levels, from technology and high-throughput screen development to target identification and functional studies. Here, we describe the RNAi screening platform that we have established and made available to the community through the Drosophila RNAi Screening Center at Harvard Medical School. We then illustrate how the combination of RNAi and small-molecule HTS can lead to effective identification of targets in drug discovery.
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Affiliation(s)
- Norbert Perrimon
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
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215
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Atilla-Gokcumen GE, Williams DS, Bregman H, Pagano N, Meggers E. Organometallic compounds with biological activity: a very selective and highly potent cellular inhibitor for glycogen synthase kinase 3. Chembiochem 2006; 7:1443-50. [PMID: 16858717 DOI: 10.1002/cbic.200600117] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A chiral second-generation organoruthenium half-sandwich compound is disclosed that shows a remarkable selectivity and cellular potency for the inhibition of glycogen synthase kinase 3 (GSK-3). The selectivity was evaluated against a panel of 57 protein kinases, in which no other kinase was inhibited to the same extent, with a selectivity window of at least tenfold to more than 1000-fold at 100 microM ATP. Furthermore, a comparison with organic GSK-3 inhibitors demonstrated the superior cellular activity of this ruthenium compound: wnt signaling was fully induced at concentrations down to 30 nM. For comparison, the well-established organic GSK-3 inhibitors 6-bromoindirubin-3'-oxime (BIO) and kenpaullone activate the wnt pathway at concentrations that are higher by around 30-fold and 100-fold, respectively. The treatment of zebrafish embryos with the organometallic inhibitor resulted in a phenotype that is typical for the inhibition of GSK-3. No phenotypic change was observed with the mirror-imaged ruthenium complex. The latter does not, in fact, show any of the pharmacological properties for the inhibition of GSK-3. Overall, these results demonstrate the potential usefulness of organometallic compounds as molecular probes in cultured cells and whole organisms.
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Affiliation(s)
- G Ekin Atilla-Gokcumen
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104, USA
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216
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Yamamoto H, Komekado H, Kikuchi A. Caveolin is necessary for Wnt-3a-dependent internalization of LRP6 and accumulation of beta-catenin. Dev Cell 2006; 11:213-23. [PMID: 16890161 DOI: 10.1016/j.devcel.2006.07.003] [Citation(s) in RCA: 242] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 06/18/2006] [Accepted: 07/12/2006] [Indexed: 01/12/2023]
Abstract
beta-catenin-mediated Wnt signaling is critical in animal development and tumor progression. The single-span transmembrane Wnt receptor, low-density lipoprotein receptor-related protein 6 (LRP6), interacts with Axin to promote the Wnt-dependent accumulation of beta-catenin. However, the molecular mechanism of receptor internalization and its impact on signaling are unclear. Here, we present evidence that LRP6 is internalized with caveolin and that the components of this endocytic pathway are required not only for Wnt-3a-induced internalization of LRP6 but also for accumulation of beta-catenin. Overall, our data suggest that Wnt-3a triggers the interaction of LRP6 with caveolin and promotes recruitment of Axin to LRP6 phosphorylated by glycogen synthase kinase-3beta and that caveolin thereby inhibits the binding of beta-catenin to Axin. Thus, caveolin plays critical roles in inducing the internalization of LRP6 and activating the Wnt/beta-catenin pathway. We also discuss the idea that distinct endocytic pathways correlate with the specificity of Wnt signaling events.
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Affiliation(s)
- Hideki Yamamoto
- Department of Biochemistry, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan
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217
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Ge H, Player CM, Zou L. Toward a global picture of development: lessons from genome-scale analysis in Caenorhabditis elegans embryonic development. Dev Dyn 2006; 235:2009-17. [PMID: 16779860 DOI: 10.1002/dvdy.20865] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Development is the result of complex events, including cascades of transcriptional programs and numerous molecular interactions. Traditionally, research focus has been given to the characterization of individual mutants, regulators, or interactions. With the availability of complete genome sequences and high-throughput (HT) experimental techniques, probing development on a system level has become feasible. Pioneering work initiated in invertebrate model systems such as Caenorhabditis elegans has provided first drafts of catalogs of essential components, transcriptional regulatory diagrams and molecular interaction networks underlying developmental processes. Integrating these drafts approximates a system-level picture of development and provides local models for protein/gene functions. Here we summarize the progress toward elucidating developmental processes on a system level, including the applications of genomic technologies and computational analyses. We discuss C. elegans embryonic development in case studies to illustrate how various HT approaches can be integrated and how biological insights can be gained from these approaches.
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Affiliation(s)
- Hui Ge
- Whitehead Institute, Cambridge, Massachusetts 02142, USA.
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218
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Rana AA, Collart C, Gilchrist MJ, Smith JC. Defining synphenotype groups in Xenopus tropicalis by use of antisense morpholino oligonucleotides. PLoS Genet 2006; 2:e193. [PMID: 17112317 PMCID: PMC1636699 DOI: 10.1371/journal.pgen.0020193] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 10/03/2006] [Indexed: 12/03/2022] Open
Abstract
To identify novel genes involved in early development, and as proof-of-principle of a large-scale reverse genetics approach in a vertebrate embryo, we have carried out an antisense morpholino oligonucleotide (MO) screen in Xenopus tropicalis, in the course of which we have targeted 202 genes expressed during gastrula stages. MOs were designed to complement sequence between −80 and +25 bases of the initiating AUG codons of the target mRNAs, and the specificities of many were tested by (i) designing different non-overlapping MOs directed against the same mRNA, (ii) injecting MOs differing in five bases, and (iii) performing “rescue” experiments. About 65% of the MOs caused X. tropicalis embryos to develop abnormally (59% of those targeted against novel genes), and we have divided the genes into “synphenotype groups,” members of which cause similar loss-of-function phenotypes and that may function in the same developmental pathways. Analysis of the expression patterns of the 202 genes indicates that members of a synphenotype group are not necessarily members of the same synexpression group. This screen provides new insights into early vertebrate development and paves the way for a more comprehensive MO-based analysis of gene function in X. tropicalis. Genome sequencing projects have provided remarkable insights into the expression and regulation of many genes. For some species, such as the invertebrates Caenorhabditis elegans and Drosophila melanogaster, it has been possible to assign functions to these genes on a genome-wide scale. For the vertebrates, similar efforts are being made in mouse and zebrafish, but work in the former species is expensive and slow, and the zebrafish experienced a whole genome duplication event, so that some genes may have retained redundant functions. Here, this study uses antisense morpholino oligonucleotides (MOs) to show that the diploid amphibian Xenopus tropicalis provides a powerful alternative species. The authors have designed MOs to target sequences around the initiating AUG codons of 202 genes expressed during early development and confirmed that these function in a specific manner. About 65% of the MOs caused embryos to develop abnormally, and the authors have divided the genes into “synphenotype groups,” members of which cause similar loss-of-function phenotypes. Expression pattern analysis indicates that members of a synphenotype group are not necessarily members of the same synexpression group. This screen provides new insights into vertebrate development and paves the way for a comprehensive MO-based analysis of gene function in X. tropicalis.
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Affiliation(s)
- Amer Ahmed Rana
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Clara Collart
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Michael J Gilchrist
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - J. C Smith
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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219
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Mukherji M, Bell R, Supekova L, Wang Y, Orth AP, Batalov S, Miraglia L, Huesken D, Lange J, Martin C, Sahasrabudhe S, Reinhardt M, Natt F, Hall J, Mickanin C, Labow M, Chanda SK, Cho CY, Schultz PG. Genome-wide functional analysis of human cell-cycle regulators. Proc Natl Acad Sci U S A 2006; 103:14819-24. [PMID: 17001007 PMCID: PMC1595435 DOI: 10.1073/pnas.0604320103] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Human cells have evolved complex signaling networks to coordinate the cell cycle. A detailed understanding of the global regulation of this fundamental process requires comprehensive identification of the genes and pathways involved in the various stages of cell-cycle progression. To this end, we report a genome-wide analysis of the human cell cycle, cell size, and proliferation by targeting >95% of the protein-coding genes in the human genome using small interfering RNAs (siRNAs). Analysis of >2 million images, acquired by quantitative fluorescence microscopy, showed that depletion of 1,152 genes strongly affected cell-cycle progression. These genes clustered into eight distinct phenotypic categories based on phase of arrest, nuclear area, and nuclear morphology. Phase-specific networks were built by interrogating knowledge-based and physical interaction databases with identified genes. Genome-wide analysis of cell-cycle regulators revealed a number of kinase, phosphatase, and proteolytic proteins and also suggests that processes thought to regulate G(1)-S phase progression like receptor-mediated signaling, nutrient status, and translation also play important roles in the regulation of G(2)/M phase transition. Moreover, 15 genes that are integral to TNF/NF-kappaB signaling were found to regulate G(2)/M, a previously unanticipated role for this pathway. These analyses provide systems-level insight into both known and novel genes as well as pathways that regulate cell-cycle progression, a number of which may provide new therapeutic approaches for the treatment of cancer.
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Affiliation(s)
- Mridul Mukherji
- *The Skaggs Institute for Chemical Biology and Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Russell Bell
- Prolexys Pharmaceuticals, Inc., 2150 West Dauntless Avenue, Salt Lake City, UT 84116
| | - Lubica Supekova
- *The Skaggs Institute for Chemical Biology and Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Yan Wang
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
| | - Anthony P. Orth
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
| | - Serge Batalov
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
| | - Loren Miraglia
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
| | - Dieter Huesken
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland; and
| | - Joerg Lange
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland; and
| | - Christopher Martin
- Prolexys Pharmaceuticals, Inc., 2150 West Dauntless Avenue, Salt Lake City, UT 84116
| | - Sudhir Sahasrabudhe
- Prolexys Pharmaceuticals, Inc., 2150 West Dauntless Avenue, Salt Lake City, UT 84116
| | - Mischa Reinhardt
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland; and
| | - Francois Natt
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland; and
| | - Jonathan Hall
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland; and
| | - Craig Mickanin
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, Inc., 250 Massachusetts Avenue, Cambridge, MA 02139
| | - Mark Labow
- Genome and Proteome Sciences, Novartis Institutes for BioMedical Research, Inc., 250 Massachusetts Avenue, Cambridge, MA 02139
| | - Sumit K. Chanda
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
| | - Charles Y. Cho
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
- To whom correspondence may be addressed. E-mail:
or
| | - Peter G. Schultz
- *The Skaggs Institute for Chemical Biology and Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121
- To whom correspondence may be addressed. E-mail:
or
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220
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Mandal D, Srivastava A, Mahlum E, Desai D, Maran A, Yaszemski M, Jalal SM, Gitelis S, Bertoni F, Damron T, Irwin R, O'connor M, Schwartz H, Bolander ME, Sarkar G. Severe suppression of Frzb/sFRP3 transcription in osteogenic sarcoma. Gene 2006; 386:131-8. [PMID: 17079093 DOI: 10.1016/j.gene.2006.08.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 07/27/2006] [Accepted: 08/21/2006] [Indexed: 11/20/2022]
Abstract
Deciphering the molecular basis of cancer is critical for developing novel diagnostic and therapeutic strategies. To better understand the early molecular events involving osteogenic sarcoma (OGS), we have initiated a program to identify potential tumor suppressor genes. Expression profiling of total RNA from ten normal bone cell lines and eleven OGS-derived cell lines by microarray showed 135-fold lower expression of FRZB/sFRP3 mRNA in OGS cells compared to bone cells; this down-regulation of Frzb/sFRP3 mRNA expression was found to be serum-independent. Subsequently, fourteen OGS biopsy specimens showed nine-fold down-regulation of Frzb/sFRP3 mRNA expression compared to expression in eight normal bone specimens as determined by microarray. FRZB /sFRP3 protein level was also found to be at a very low level in 4/4 OGS cell lines examined. Quantitation by RT-PCR indicated approximately 70% and approximately 90% loss of Frzb/sFRP3 mRNA expression in OGS biopsy specimens and OGS-derived cell lines respectively, compared to expression in bone (p<0.0001). Hybridization experiments of a cDNA microarray containing paired normal and tumor specimens from nineteen different organs did not show any significant difference in the level of Frzb/sFRP3 mRNA expression between the normal and the corresponding tumor tissues. Exogenous expression of FRZB/sFRP3 mRNA in two OGS-derived cell lines lacking endogenous expression of the mRNA produced abundant mRNA from the exogenous gene, eliminating degradation as a possibility for very low level of FRZB/sFRP3 mRNA in OGS specimens. Results from PCR-based experiments suggest that the FRZB/sFRP3 gene is not deleted in OGS cell lines, however, karyotyping shows gross abnormalities involving chromosome 2 (location of the FRZB gene) in five of twelve OGS-derived cell lines. Together, these data suggest a tumor-suppressive potential for FRZB/sFRP3 in OGS.
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Affiliation(s)
- Deendayal Mandal
- Department of Orthopedic Research, Mayo Clinic and Foundation, 200 1st St. SW, Rochester, MN 55905, USA
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221
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Ma Y, Creanga A, Lum L, Beachy PA. Prevalence of off-target effects in Drosophila RNA interference screens. Nature 2006; 443:359-63. [PMID: 16964239 DOI: 10.1038/nature05179] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 08/17/2006] [Indexed: 01/25/2023]
Abstract
RNA interference (RNAi) in both plants and animals is mediated by small RNAs of approximately 21-23 nucleotides in length for regulation of target gene expression at multiple levels through partial sequence complementarities. Combined with widespread genome sequencing, experimental use of RNAi has the potential to interrogate systematically all genes in a given organism with respect to a particular function. However, owing to a tolerance for mismatches and gaps in base-pairing with targets, small RNAs could have up to hundreds of potential target sequences in a genome, and some small RNAs in mammalian systems have been shown to affect the levels of many messenger RNAs besides their intended targets. The use of long double-stranded RNAs (dsRNAs) in Drosophila, where Dicer-mediated processing produces small RNAs inside cells, has been thought to reduce the probability of such 'off-target effects' (OTEs). Here we show, however, that OTEs mediated by short homology stretches within long dsRNAs are prevalent in Drosophila. We have performed a genome-wide RNAi screen for novel components of Wingless (Wg) signal transduction in Drosophila S2R + cells, and found few, if any, legitimate candidates. Rather, many of the top candidates exert their effects on Wg response through OTEs on known pathway components or through promiscuous OTEs produced by tandem trinucleotide repeats present in many dsRNAs and genes. Genes containing such repeats are over-represented in candidate lists from published screens, suggesting that they represent a common class of false positives. Our results suggest simple measures to improve the reliability of genome-wide RNAi screens in Drosophila and other organisms.
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Affiliation(s)
- Yong Ma
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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222
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Costanzo M, Giaever G, Nislow C, Andrews B. Experimental approaches to identify genetic networks. Curr Opin Biotechnol 2006; 17:472-80. [PMID: 16962766 DOI: 10.1016/j.copbio.2006.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 08/10/2006] [Accepted: 08/31/2006] [Indexed: 01/09/2023]
Abstract
Systems biology offers the promise of a fully integrated view of cellular physiology. To realize this potential requires the analysis of diverse genome-wide datasets and the incorporation of these analyses into integrated networks. In the past decade, the budding yeast Saccharomyces cerevisiae has provided the benchmark for the design of such large-scale experiments. Many of these experimental approaches have been adopted and adapted to study other systems, including worm, fly, fish and mammalian cultured cells, using an ingenious set of molecular tools.
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Affiliation(s)
- Michael Costanzo
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
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223
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Hayward P, Balayo T, Martinez Arias A. Notch synergizes with axin to regulate the activity of armadillo in Drosophila. Dev Dyn 2006; 235:2656-66. [PMID: 16881048 DOI: 10.1002/dvdy.20902] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Cell fate decisions require the integration of various signalling inputs at the level of transcription and signal transduction. Wnt and Notch signalling are two important signalling systems that operate in concert in a variety of systems in vertebrates and invertebrates. There is evidence that the Notch receptor can modulate Wnt signalling and that its target is the activity and levels of Armadillo/beta-catenin. Here, we characterize this function of Notch in relation to Axin, a key element in the regulation of Wnt signalling that acts as a scaffold for the Shaggy/GSK3beta-dependent phosphorylation of Armadillo/beta-catenin. While Notch can regulate ectopic Wingless signalling caused by loss of function of Shaggy, it can only partially regulate the ectopic Wnt signalling induced by the loss of Axin function. The same interactions are observed in tissue culture cells where we observe a synergy in between Axin and Notch in the regulation of Armadillo/beta-catenin. Our results provide evidence for a function of Axin in the regulation of Armadillo that is different from its role as a scaffold for GSK3beta.
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Affiliation(s)
- Penelope Hayward
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
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224
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Waldrop S, Chan CC, Cagatay T, Zhang S, Rousset R, Mack J, Zeng W, Fish M, Zhang M, Amanai M, Wharton KA. An unconventional nuclear localization motif is crucial for function of the Drosophila Wnt/wingless antagonist Naked cuticle. Genetics 2006; 174:331-48. [PMID: 16849595 PMCID: PMC1569797 DOI: 10.1534/genetics.106.061853] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Wnt/beta-catenin signals orchestrate cell fate and behavior throughout the animal kingdom. Aberrant Wnt signaling impacts nearly the entire spectrum of human disease, including birth defects, cancer, and osteoporosis. If Wnt signaling is to be effectively manipulated for therapeutic advantage, we first must understand how Wnt signals are normally controlled. Naked cuticle (Nkd) is a novel and evolutionarily conserved inducible antagonist of Wnt/beta-catenin signaling that is crucial for segmentation in the model genetic organism, the fruit fly Drosophila melanogaster. Nkd can bind and inhibit the Wnt signal transducer Dishevelled (Dsh), but the mechanism by which Nkd limits Wnt signaling in the fly embryo is not understood. Here we show that nkd mutants exhibit elevated levels of the beta-catenin homolog Armadillo but no alteration in Dsh abundance or distribution. In the fly embryo, Nkd and Dsh are predominantly cytoplasmic, although a recent report suggests that vertebrate Dsh requires nuclear localization for activity in gain-of-function assays. While Dsh-binding regions of Nkd contribute to its activity, we identify a conserved 30-amino-acid motif, separable from Dsh-binding regions, that is essential for Nkd function and nuclear localization. Replacement of the 30-aa motif with a conventional nuclear localization sequence rescued a small fraction of nkd mutant animals to adulthood. Our studies suggest that Nkd targets Dsh-dependent signal transduction steps in both cytoplasmic and nuclear compartments of cells receiving the Wnt signal.
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Affiliation(s)
- Sharon Waldrop
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9072, USA
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225
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Ma’ayan A, Gardiner K, Iyengar R. The cognitive phenotype of Down syndrome: insights from intracellular network analysis. NeuroRx 2006; 3:396-406. [PMID: 16815222 PMCID: PMC3032589 DOI: 10.1016/j.nurx.2006.05.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Down syndrome (DS) is caused by trisomy of chromosome 21. All individuals with DS exhibit some level of cognitive dysfunction. It is generally accepted that these abnormalities are a result of the upregulation of genes encoded by chromosome 21. Many chromosome 21 proteins are known or predicted to function in critical neurological processes, but typically they function as modulators of these processes, not as key regulators. Thus, upregulation in DS is expected to cause only modest perturbations of normal processes. Systematic approaches such as intracellular network construction and analysis have not been generally applied in DS research. Networks can be assembled from high-throughput experiments or by text-mining of experimental literature. We survey some new developments in constructing such networks, focusing on newly developed network analysis methodologies. We propose how these methods could be integrated with creation and manipulation of mouse models of DS to advance our understanding of the perturbed cell signaling pathways in DS. This understanding could lead to potential therapeutics.
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Affiliation(s)
- Avi Ma’ayan
- />Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, 10029 New York, New York
| | - Katheleen Gardiner
- />Eleanor Roosevelt Institute at the University of Denver, University of Colorado at Denver and the Health Sciences Center, 80206 Denver, Colorado
| | - Ravi Iyengar
- />Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, 10029 New York, New York
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226
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Rosenfeld MG, Lunyak VV, Glass CK. Sensors and signals: a coactivator/corepressor/epigenetic code for integrating signal-dependent programs of transcriptional response. Genes Dev 2006; 20:1405-28. [PMID: 16751179 DOI: 10.1101/gad.1424806] [Citation(s) in RCA: 696] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A decade of intensive investigation of coactivators and corepressors required for regulated actions of DNA-binding transcription factors has revealed a network of sequentially exchanged cofactor complexes that execute a series of enzymatic modifications required for regulated gene expression. These coregulator complexes possess "sensing" activities required for interpretation of multiple signaling pathways. In this review, we examine recent progress in understanding the functional consequences of "molecular sensor" and "molecular adaptor" actions of corepressor/coactivator complexes in integrating signal-dependent programs of transcriptional responses at the molecular level. This strategy imposes a temporal order for modifying programs of transcriptional regulation in response to the cellular milieu, which is used to mediate developmental/homeostatic and pathological events.
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Affiliation(s)
- Michael G Rosenfeld
- Howard Hughes Medical Institute, Department of Molecular Medicine, University of California, San Diego, La Jolla, California 92093, USA.
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227
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Echeverri CJ, Perrimon N. High-throughput RNAi screening in cultured cells: a user's guide. Nat Rev Genet 2006; 7:373-84. [PMID: 16607398 DOI: 10.1038/nrg1836] [Citation(s) in RCA: 263] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
RNA interference has re-energized the field of functional genomics by enabling genome-scale loss-of-function screens in cultured cells. Looking back on the lessons that have been learned from the first wave of technology developments and applications in this exciting field, we provide both a user's guide for newcomers to the field and a detailed examination of some more complex issues, particularly concerning optimization and quality control, for more advanced users. From a discussion of cell lines, screening paradigms, reagent types and read-out methodologies, we explore in particular the complexities of designing optimal controls and normalization strategies for these challenging but extremely powerful studies.
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228
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Seto ES, Bellen HJ. Internalization is required for proper Wingless signaling in Drosophila melanogaster. ACTA ACUST UNITED AC 2006; 173:95-106. [PMID: 16606693 PMCID: PMC2063794 DOI: 10.1083/jcb.200510123] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Wnt–Wingless (Wg) pathway regulates development through precisely controlled signaling. In this study, we show that intracellular trafficking regulates Wg signaling levels. In Drosophila melanogaster cells stimulated with Wg media, dynamin or Rab5 knockdown causes reduced Super8XTOPflash activity, suggesting that internalization and endosomal transport facilitate Wg signaling. In the wing, impaired dynamin function reduces Wg transcription. However, when Wg production is unaffected, extracellular Wg levels are increased. Despite this, target gene expression is reduced, indicating that internalization is also required for efficient Wg signaling in vivo. When endosomal transport is impaired, Wg signaling is similarly reduced. Conversely, the expression of Wg targets is enhanced by increased transport to endosomes or decreased hepatocyte growth factor–regulated tyrosine kinase substrate– mediated transport from endosomes. This increased signaling correlates with greater colocalized Wg, Arrow, and Dishevelled on endosomes. As these data indicate that endosomal transport promotes Wg signaling, our findings suggest that the regulation of endocytosis is a novel mechanism through which Wg signaling levels are determined.
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Affiliation(s)
- Elaine S Seto
- Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
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229
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Voutev R, Killian DJ, Ahn JH, Hubbard EJA. Alterations in ribosome biogenesis cause specific defects in C. elegans hermaphrodite gonadogenesis. Dev Biol 2006; 298:45-58. [PMID: 16876152 DOI: 10.1016/j.ydbio.2006.06.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2006] [Revised: 05/21/2006] [Accepted: 06/02/2006] [Indexed: 12/16/2022]
Abstract
Ribosome biogenesis is a cell-essential process that influences cell growth, proliferation, and differentiation. How ribosome biogenesis impacts development, however, is poorly understood. Here, we establish a link between ribosome biogenesis and gonadogenesis in Caenorhabditis elegans that affects germline proliferation and patterning. Previously, we determined that pro-1(+)activity is required in the soma--specifically, the sheath/spermatheca sublineage--to promote normal proliferation and prevent germline tumor formation. Here, we report that PRO-1, like its yeast ortholog IPI3, influences rRNA processing. pro-1 tumors are suppressed by mutations in ncl-1 or lin-35/Rb, both of which elevate pre-rRNA levels. Thus, in this context, lin-35/Rb acts as a soma-autonomous germline tumor promoter. We further report the characterization of two additional genes identified for their germline tumor phenotype, pro-2 and pro-3, and find that they, too, encode orthologs of proteins involved in ribosome biogenesis in yeast (NOC2 and SDA1, respectively). Finally, we demonstrate that depletion of additional C. elegans orthologs of yeast ribosome biogenesis factors display phenotypes similar to depletion of progenes. We conclude that the C. elegans distal sheath is particularly sensitive to alterations in ribosome biogenesis and that ribosome biogenesis defects in one tissue can non-autonomously influence proliferation in an adjacent tissue.
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Affiliation(s)
- Roumen Voutev
- Department of Biology, New York University, New York, NY 10003-6688, USA
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230
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Zhang SL, Yeromin AV, Zhang XHF, Yu Y, Safrina O, Penna A, Roos J, Stauderman KA, Cahalan MD. Genome-wide RNAi screen of Ca(2+) influx identifies genes that regulate Ca(2+) release-activated Ca(2+) channel activity. Proc Natl Acad Sci U S A 2006; 103:9357-62. [PMID: 16751269 PMCID: PMC1482614 DOI: 10.1073/pnas.0603161103] [Citation(s) in RCA: 707] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Recent studies by our group and others demonstrated a required and conserved role of Stim in store-operated Ca(2+) influx and Ca(2+) release-activated Ca(2+) (CRAC) channel activity. By using an unbiased genome-wide RNA interference screen in Drosophila S2 cells, we now identify 75 hits that strongly inhibited Ca(2+) influx upon store emptying by thapsigargin. Among these hits are 11 predicted transmembrane proteins, including Stim, and one, olf186-F, that upon RNA interference-mediated knockdown exhibited a profound reduction of thapsigargin-evoked Ca(2+) entry and CRAC current, and upon overexpression a 3-fold augmentation of CRAC current. CRAC currents were further increased to 8-fold higher than control and developed more rapidly when olf186-F was cotransfected with Stim. olf186-F is a member of a highly conserved family of four-transmembrane spanning proteins with homologs from Caenorhabditis elegans to human. The endoplasmic reticulum (ER) Ca(2+) pump sarco-/ER calcium ATPase (SERCA) and the single transmembrane-soluble N-ethylmaleimide-sensitive (NSF) attachment receptor (SNARE) protein Syntaxin5 also were required for CRAC channel activity, consistent with a signaling pathway in which Stim senses Ca(2+) depletion within the ER, translocates to the plasma membrane, and interacts with olf186-F to trigger CRAC channel activity.
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Affiliation(s)
- Shenyuan L. Zhang
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
| | - Andriy V. Yeromin
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
| | - Xiang H.-F. Zhang
- Department of Biological Sciences, Columbia University, New York, NY 10027; and
| | - Ying Yu
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
| | - Olga Safrina
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
| | - Aubin Penna
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
| | - Jack Roos
- TorreyPines Therapeutics, Inc., La Jolla, CA 92037
| | | | - Michael D. Cahalan
- *Department of Physiology and Biophysics and Center for Immunology, University of California, Irvine, CA 92697
- To whom correspondence should be addressed. E-mail:
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231
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Abstract
The Wnt signaling pathway controls cell proliferation and body patterning throughout development. A surprising number of cytoplasmic Wnt regulators (e.g., beta-catenin, Bcl-9/Lgs, APC, Axin) also appear, often transiently, in the nucleus. beta-Catenin is an integral component of E-cadherin complexes at intercellular adherens junctions, but also recruits chromatin remodeling complexes to activate transcription in the nucleus. The APC tumor suppressor is a part of the cytoplasmic beta-catenin destruction complex, yet also counteracts beta-catenin transactivation and histone H3K4 methylation at Wnt target genes. Furthermore, APC coordinates the cyclic exchange of Wnt coregulator complexes at the DNA. These opposing roles of APC and beta-catenin enable a rapid coordination of gene expression and cytoskeletal organization throughout the cell in response to signaling.
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Affiliation(s)
- Karl Willert
- Department of Molecular and Cellular Medicine, University of California, San Diego, La Jolla, California 92093, USA
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232
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Abstract
A genome-wide RNA interference screen in Drosophila cells has identified genes involved in regulating cell-cycle progression, cell size and apoptosis. Cell-based genome-wide RNA interference screens are being used to address an increasingly broad spectrum of biological questions. In one recent screen, Drosophila cell cultures treated with double-stranded RNA were analyzed by flow cytometry, providing a wealth of new information and identifying 488 regulators of the cell cycle, cell size, and cell death.
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Affiliation(s)
- Megan J Cully
- Signal Transduction Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Sally J Leevers
- Growth Regulation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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233
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Price MA. CKI, there's more than one: casein kinase I family members in Wnt and Hedgehog signaling. Genes Dev 2006; 20:399-410. [PMID: 16481469 DOI: 10.1101/gad.1394306] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Multiple members of the casein kinase I family of serine/threonine protein kinases are involved in positive and negative roles in Wnt and Hedgehog signaling. Here I review these roles, including recent results on casein kinase I (CKI) phosphorylation and activation of LRP6, and CKI phosphorylation of Ci and mediation of Ci-Slimb/beta-TrCP binding.
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Affiliation(s)
- Mary Ann Price
- Centre for Developmental and Biomedical Genetics, Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom.
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234
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Fang M, Li J, Blauwkamp T, Bhambhani C, Campbell N, Cadigan KM. C-terminal-binding protein directly activates and represses Wnt transcriptional targets in Drosophila. EMBO J 2006; 25:2735-45. [PMID: 16710294 PMCID: PMC1500853 DOI: 10.1038/sj.emboj.7601153] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 04/27/2006] [Indexed: 01/27/2023] Open
Abstract
Regulation of Wnt transcriptional targets is thought to occur by a transcriptional switch. In the absence of Wnt signaling, sequence-specific DNA-binding proteins of the TCF family repress Wnt target genes. Upon Wnt stimulation, stabilized beta-catenin binds to TCFs, converting them into transcriptional activators. C-terminal-binding protein (CtBP) is a transcriptional corepressor that has been reported to inhibit Wnt signaling by binding to TCFs or by preventing beta-catenin from binding to TCF. Here, we show that CtBP is also required for the activation of some Wnt targets in Drosophila. CtBP is recruited to Wnt-regulated enhancers in a Wnt-dependent manner, where it augments Armadillo (the fly beta-catenin) transcriptional activation. We also found that CtBP is required for repression of a subset of Wnt targets in the absence of Wnt stimulation, but in a manner distinct from previously reported mechanisms. CtBP binds to Wnt-regulated enhancers in a TCF-independent manner and represses target genes in parallel with TCF. Our data indicate dual roles for CtBP as a gene-specific activator and repressor of Wnt target gene transcription.
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Affiliation(s)
- Ming Fang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jiong Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Timothy Blauwkamp
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Chandan Bhambhani
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Nathan Campbell
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ken M Cadigan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA. Tel.: +1 734 936 3246; Fax: +1 734 647 0884; E-mail:
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235
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Abstract
Technological advances in mammalian systems are providing new tools to identify the molecular components of signalling pathways. Foremost among these tools is the ability to knock down gene function through the use of RNA interference (RNAi). The fact that RNAi can be scaled up for use in high-throughput techniques has motivated the creation of genome-wide RNAi reagents. We are now at the brink of being able to harness the power of RNAi for large-scale functional discovery in mammalian cells.
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Affiliation(s)
- Jason Moffat
- Whitehead Institute, 9 Cambridge Center, Cambridge, Massachusetts 02142, USA
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236
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Ando H, Okamoto H. Efficient transfection strategy for the spatiotemporal control of gene expression in zebrafish. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2006; 8:295-303. [PMID: 16614871 DOI: 10.1007/s10126-005-5138-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Accepted: 11/09/2005] [Indexed: 05/08/2023]
Abstract
Functional analyses of gene function by knockdown and expression approaches strongly enhance the genetic study of development. In vivo application of the introduction of inhibitors of gene expression, mRNA, and expression constructs in the target region make it possible to perform region- and stage-specific regulation of gene function in a simple manner. As a basic tool for the conditional regulation of gene expression in target tissue, we present methods for the efficient introduction of antisense morpholino oligonucleotide (MO), mRNA, and expression plasmid constructs into early and later stage zebrafish embryo and larva. Lipofection of a neuron-specific expression construct plasmid encoding green fluorescent protein (GFP) into optic vesicle resulted in clear GFP expression in the retinotectal pathway in hatched larva. Co-lipofection of MO and GFP mRNA to the presumptive head region resulted in brain-specific knockdown of the gene in mid-stage embryos.
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Affiliation(s)
- Hideki Ando
- Laboratory for Developmental Gene Regulation, Brain Science Institute, RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama, 351-0198, Japan.
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237
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Bartscherer K, Pelte N, Ingelfinger D, Boutros M. Secretion of Wnt Ligands Requires Evi, a Conserved Transmembrane Protein. Cell 2006; 125:523-33. [PMID: 16678096 DOI: 10.1016/j.cell.2006.04.009] [Citation(s) in RCA: 420] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 01/23/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
Wnt signaling pathways are important for multiple biological processes during development and disease. Wnt proteins are secreted factors that activate target-gene expression in both a short- and long-range manner. Currently, little is known about how Wnts are released from cells and which factors facilitate their secretion. Here, we identify a conserved multipass transmembrane protein, Evenness interrupted (Evi/Wls), through an RNAi survey for transmembrane proteins involved in Drosophila Wingless (Wg) signaling. During development, evi mutants have patterning defects that phenocopy wg loss-of-function alleles and fail to express Wg target genes. evi's function is evolutionarily conserved as depletion of its human homolog disrupts Wnt signaling in human cells. Epistasis experiments and clonal analysis place evi in the Wg-producing cell. Our results show that Wg is retained by evi mutant cells and suggest that evi is the founding member of a gene family specifically required for Wg/Wnt secretion.
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Affiliation(s)
- Kerstin Bartscherer
- German Cancer Research Center, Boveri-Group Signaling and Functional Genomics, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
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238
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Abstract
An RNAi screen in Drosophila cells has identified about 100 TANGO proteins, which may regulate protein exocytosis or secretion. Although the organization and functions of the constitutive secretory pathway have been intensively studied for decades, a recent genome-wide RNAi screen in Drosophila cells has identified about 100 genes encoding novel so-called TANGO proteins (for transport and Golgi organization) that may be direct regulators of various aspects of protein exocytosis or secretion.
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Affiliation(s)
- Catherine Rabouille
- University Medical Center Utrecht, The Cell Microscopy Center, Department of Cell Biology and Institute of Biomembranes, Heidelberglaan 100, 3584CX Utrecht, The Netherlands.
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239
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Langdon T, Hayward P, Brennan K, Wirtz-Peitz F, Sanders P, Zecchini V, Friday A, Balayo T, Martinez Arias A. Notch receptor encodes two structurally separable functions inDrosophila: A genetic analysis. Dev Dyn 2006; 235:998-1013. [PMID: 16534797 DOI: 10.1002/dvdy.20735] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The Notch gene of Drosophila encodes a single transmembrane receptor that plays a central role in the process of lateral inhibition. This process results in the selection of individual mesodermal and neural precursors during the development of the muscular and nervous systems. The activation of Notch during lateral inhibition is mediated by the transmembrane ligand Delta (Dl) and effected by the transcription factor Suppressor of Hairless (Su(H)). The same functional cassette plays a role in other processes, in particular, the development and patterning of the wing. Genetic analysis has suggested that, in addition to the Su(H)-dependent pathway, Notch can signal in an Su(H)-independent manner. This process seems to be tightly associated with signalling by Wingless, a member of the Wnt family of signalling molecules. Here, we have analyzed further the possibility that the Notch protein encodes two different functions. To do so, we have studied the activities and genetic properties of different Notch receptors bearing deletions of specific regions of the intracellular and the extracellular domains in different developmental processes, and have sought to correlate the activity of these mutant proteins with those of existing mutants in Notch. Our results support the existence of at least two different activities of Notch each of which can be associated with specific structural domains.
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Affiliation(s)
- Tim Langdon
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, U.K
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240
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Varjosalo M, Li SP, Taipale J. Divergence of hedgehog signal transduction mechanism between Drosophila and mammals. Dev Cell 2006; 10:177-86. [PMID: 16459297 DOI: 10.1016/j.devcel.2005.12.014] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 11/24/2005] [Accepted: 12/27/2005] [Indexed: 11/27/2022]
Abstract
The Hedgehog (Hh) signaling pathway has conserved roles in development of species ranging from Drosophila to humans. Responses to Hh are mediated by the transcription factor Cubitus interruptus (Ci; GLIs 1-3 in mammals), and constitutive activation of Hh target gene expression has been linked to several types of human cancer. In Drosophila, the kinesin-like protein Costal2 (Cos2), which associates directly with the Hh receptor component Smoothened (Smo), is essential for suppression of the transcriptional activity of Ci in the absence of ligand. Another protein, Suppressor of Fused (Su(Fu)), exerts a weak negative influence on Ci activity. Based on analysis of functional and sequence conservation of Cos2 orthologs, Su(Fu), Smo, and Ci/GLI proteins, we find here that Drosophila and mammalian Hh signaling mechanisms have diverged, and that, in mouse cells, major Cos2-like activities are absent and the inhibition of the Hh pathway in the absence of ligand critically depends on Su(Fu).
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Affiliation(s)
- Markku Varjosalo
- Molecular and Cancer Biology Program, Biomedicum, University of Helsinki and Department of Molecular Medicine, National Public Health Institute, P.O. Box 63, Helsinki FIN-00014, Finland
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241
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Rives AF, Rochlin KM, Wehrli M, Schwartz SL, DiNardo S. Endocytic trafficking of Wingless and its receptors, Arrow and DFrizzled-2, in the Drosophila wing. Dev Biol 2006; 293:268-83. [PMID: 16530179 PMCID: PMC7897421 DOI: 10.1016/j.ydbio.2006.02.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 02/03/2006] [Accepted: 02/06/2006] [Indexed: 11/19/2022]
Abstract
During animal development, Wnt/Wingless (Wg) signaling is required for the patterning of multiple tissues. While insufficient signal transduction is detrimental to normal development, ectopic activation of the pathway can be just as devastating. Thus, numerous controls exist to precisely regulate Wg signaling levels. Endocytic trafficking of pathway components has recently been proposed as one such control mechanism. Here, we characterize the vesicular trafficking of Wg and its receptors, Arrow and DFrizzled-2 (DFz2), and investigate whether trafficking is important to regulate Wg signaling during dorsoventral patterning of the larval wing. We demonstrate a role for Arrow and DFz2 in Wg internalization. Subsequently, Wg, Arrow and DFz2 are trafficked through the endocytic pathway to the lysosome, where they are degraded in a hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs)-dependent manner. Surprisingly, we find that Wg signaling is not attenuated by lysosomal targeting in the wing disc. Rather, we suggest that signaling is dampened intracellularly at an earlier trafficking step. This is in contrast to patterning of the embryonic epidermis, where lysosomal targeting is required to restrict the range of Wg signaling. Thus, signal modulation by endocytic routing will depend on the tissue to be patterned and the goals during that patterning event.
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Affiliation(s)
- Anna F. Rives
- University of Pennsylvania School of Medicine, Department of Cell and Developmental Biology, Philadelphia, PA 190104-6058, USA
| | - Kate M. Rochlin
- University of Pennsylvania School of Medicine, Department of Cell and Developmental Biology, Philadelphia, PA 190104-6058, USA
| | - Marcel Wehrli
- Oregon Health and Science University, Department of Cell and Developmental Biology, Portland, OR 97201-3098, USA
| | - Stephanie L. Schwartz
- University of Pennsylvania School of Medicine, Department of Cell and Developmental Biology, Philadelphia, PA 190104-6058, USA
| | - Stephen DiNardo
- University of Pennsylvania School of Medicine, Department of Cell and Developmental Biology, Philadelphia, PA 190104-6058, USA
- Corresponding author. Fax: +1 215 898 9871. (S. DiNardo)
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242
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Antinozzi PA, Garcia-Diaz A, Hu C, Rothman JE. Functional mapping of disease susceptibility loci using cell biology. Proc Natl Acad Sci U S A 2006; 103:3698-703. [PMID: 16537450 PMCID: PMC1533777 DOI: 10.1073/pnas.0510521103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In most genome-wide linkage studies, implication of a causative disease gene often requires years of expanding the study to more families and finer mapping of the initially described region. Even after such efforts, unobtainable sample sizes can be required to make statistically meaningful conclusions about a single gene. Here we demonstrate that by adding a layer of functional biology to statistical genetic results, this process can be accelerated. The diabetes susceptibility locus (chromosome 18p11) was systematically dissected by using a cell-based secretion assay and RNA interference, and we identified laminin alpha1 to have a role in pancreatic beta cell secretion. The screen was extended to identify laminin receptor 1 as a functional partner in regards to beta cell function. Our approach can potentially be widely used in the setting of high-throughput cellular screening of other loci to identify candidate genes.
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Affiliation(s)
- Peter A. Antinozzi
- The Judith P. Sulzberger, M.D., Columbia Genome Center and Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, Russ Berrie Pavilion, Floor 5, New York, NY 10032
- *To whom correspondence may be addressed. E-mail:
or
| | - Alejandro Garcia-Diaz
- The Judith P. Sulzberger, M.D., Columbia Genome Center and Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, Russ Berrie Pavilion, Floor 5, New York, NY 10032
| | - Chuan Hu
- The Judith P. Sulzberger, M.D., Columbia Genome Center and Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, Russ Berrie Pavilion, Floor 5, New York, NY 10032
| | - James E. Rothman
- The Judith P. Sulzberger, M.D., Columbia Genome Center and Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, Russ Berrie Pavilion, Floor 5, New York, NY 10032
- *To whom correspondence may be addressed. E-mail:
or
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243
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Flockhart I, Booker M, Kiger A, Boutros M, Armknecht S, Ramadan N, Richardson K, Xu A, Perrimon N, Mathey-Prevot B. FlyRNAi: the Drosophila RNAi screening center database. Nucleic Acids Res 2006; 34:D489-94. [PMID: 16381918 PMCID: PMC1347476 DOI: 10.1093/nar/gkj114] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
RNA interference (RNAi) has become a powerful tool for genetic screening in Drosophila. At the Drosophila RNAi Screening Center (DRSC), we are using a library of over 21 000 double-stranded RNAs targeting known and predicted genes in Drosophila. This library is available for the use of visiting scientists wishing to perform full-genome RNAi screens. The data generated from these screens are collected in the DRSC database () in a flexible format for the convenience of the scientist and for archiving data. The long-term goal of this database is to provide annotations for as many of the uncharacterized genes in Drosophila as possible. Data from published screens are available to the public through a highly configurable interface that allows detailed examination of the data and provides access to a number of other databases and bioinformatics tools.
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Affiliation(s)
- Ian Flockhart
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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244
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Bard F, Casano L, Mallabiabarrena A, Wallace E, Saito K, Kitayama H, Guizzunti G, Hu Y, Wendler F, Dasgupta R, Perrimon N, Malhotra V. Functional genomics reveals genes involved in protein secretion and Golgi organization. Nature 2006; 439:604-7. [PMID: 16452979 DOI: 10.1038/nature04377] [Citation(s) in RCA: 276] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 10/18/2005] [Indexed: 11/08/2022]
Abstract
Yeast genetics and in vitro biochemical analysis have identified numerous genes involved in protein secretion. As compared with yeast, however, the metazoan secretory pathway is more complex and many mechanisms that regulate organization of the Golgi apparatus remain poorly characterized. We performed a genome-wide RNA-mediated interference screen in a Drosophila cell line to identify genes required for constitutive protein secretion. We then classified the genes on the basis of the effect of their depletion on organization of the Golgi membranes. Here we show that depletion of class A genes redistributes Golgi membranes into the endoplasmic reticulum, depletion of class B genes leads to Golgi fragmentation, depletion of class C genes leads to aggregation of Golgi membranes, and depletion of class D genes causes no obvious change. Of the 20 new gene products characterized so far, several localize to the Golgi membranes and the endoplasmic reticulum.
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Affiliation(s)
- Frederic Bard
- Cell and Developmental Biology Department, University of California San Diego, La Jolla, California 92093-0634, USA
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245
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Arias AM, Hayward P. Filtering transcriptional noise during development: concepts and mechanisms. Nat Rev Genet 2006; 7:34-44. [PMID: 16369570 DOI: 10.1038/nrg1750] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The assignation of cell fates during eukaryotic development relies on the coordinated and stable expression of cohorts of genes within cell populations. The precise and reproducible nature of this process is remarkable given that, at the single-cell level, the transcription of individual genes is associated with noise - random molecular fluctuations that create variability in the levels of gene expression within a cell population. Here we consider the implications of transcriptional noise for development and suggest the existence of molecular devices that are dedicated to filtering noise. On the basis of existing evidence, we propose that one such mechanism might depend on the Wnt signalling pathway.
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246
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Park JW, Graveley BR. Use of RNA interference to dissect the roles of trans-acting factors in alternative pre-mRNA splicing. Methods 2006; 37:341-4. [PMID: 16314263 PMCID: PMC2373254 DOI: 10.1016/j.ymeth.2005.07.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 07/06/2005] [Indexed: 10/25/2022] Open
Abstract
RNA interference (RNAi) is becoming a popular method for analyzing gene function in a variety of biological processes. We have used RNAi in cultured Drosophila cells to identify trans-acting factors that regulate the alternative splicing of endogenously transcribed pre-mRNAs. We have generated a dsRNA library comprising approximately 70% of the Drosophila genes encoding RNA binding proteins and assessed the function of each protein in the regulation of alternative splicing. This approach not only identifies trans-acting factors regulating specific alternative splicing events, but also can provide insight into the alternative splicing regulatory networks of Drosophila. Here, we describe this RNAi approach to identify alternative splicing regulatory proteins in detail.
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Affiliation(s)
| | - Brenton R. Graveley
- * Corresponding author. Fax: +1 860 679 8345. E-mail address: (B.R. Graveley)
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247
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Abstract
The basic vertebrate body plan of the zebrafish embryo is established in the first 10 hours of development. This period is characterized by the formation of the anterior-posterior and dorsal-ventral axes, the development of the three germ layers, the specification of organ progenitors, and the complex morphogenetic movements of cells. During the past 10 years a combination of genetic, embryological, and molecular analyses has provided detailed insights into the mechanisms underlying this process. Maternal determinants control the expression of transcription factors and the location of signaling centers that pattern the blastula and gastrula. Bmp, Nodal, FGF, canonical Wnt, and retinoic acid signals generate positional information that leads to the restricted expression of transcription factors that control cell type specification. Noncanonical Wnt signaling is required for the morphogenetic movements during gastrulation. We review how the coordinated interplay of these molecules determines the fate and movement of embryonic cells.
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Affiliation(s)
- Alexander F Schier
- Developmental Genetics Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016-6497, USA.
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248
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Buonocore F, Libertini A, Prugnoli D, Mazzini M, Scapigliati G. Production and characterization of a continuous embryonic cell line from sea bass (Dicentrarchus labrax L.). MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2006; 8:80-5. [PMID: 16249966 DOI: 10.1007/s10126-005-5032-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Accepted: 06/26/2005] [Indexed: 05/05/2023]
Abstract
Continuous cell lines represent an important tool both for biological studies and for their applications in marine biotechnology. In this article we describe the production and characterization of a continuous adherent cell line, named DLEC, derived from early embryos of the European sea bass Dicentrarchus labrax L. (Actinopterygii, Moronidae). Cells were obtained by disrupting 2- to 12-hour-old embryos and culturing resulting cells at 18 degrees C in RPMI medium containing 5% fetal calf serum (FCS) and 10% supernatant fraction of the embryo homogenate. After 8 weeks culture medium was replaced with Liebovitz's L15 medium containing 10% FCS and DLEC cells started proliferation. Subsequently, they were continuously cultured until the 50th passage without evident changes in their morphology. DLEC cells show a fibroblast-like shape and a modal chromosome number of 48, as do the wild-type cells; conversely the constant presence of six to nine meta-submetacentric elements in the karyotype (vs. zero to two in the wild-type) indicates the occurrence of chromosomal rearrangements during stabilization. DLEC cells are sensitive to substances known to induce differentiation of mammalian cells such as retinoic acid and phorbol esters. They have been transfected using liposomes with a commercial plasmid vector containing a reporter gene, thus suggesting a possible importance as an alternative expression system of recombinant vertebrate proteins in teleost cells.
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Affiliation(s)
- Francesco Buonocore
- Dipartimento di Scienze Ambientali, Università della Tuscia, Largo dell'Università, I-0110, Viterbo, Italy.
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249
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Boutros M, Brás LP, Huber W. Analysis of cell-based RNAi screens. Genome Biol 2006; 7:R66. [PMID: 16869968 PMCID: PMC1779553 DOI: 10.1186/gb-2006-7-7-r66] [Citation(s) in RCA: 247] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 06/07/2006] [Accepted: 07/25/2006] [Indexed: 02/05/2023] Open
Abstract
RNA interference (RNAi) screening is a powerful technology for functional characterization of biological pathways. Interpretation of RNAi screens requires computational and statistical analysis techniques. We describe a method that integrates all steps to generate a scored phenotype list from raw data. It is implemented in an open-source Bioconductor/R package, cellHTS (http://www.dkfz.de/signaling/cellHTS). The method is useful for the analysis and documentation of individual RNAi screens. Moreover, it is a prerequisite for the integration of multiple experiments.
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Affiliation(s)
- Michael Boutros
- Signaling and Functional Genomics, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Lígia P Brás
- EMBL - European Bioinformatics Institute, Cambridge CB10 1SD, UK
- Centre for Chemical and Biological Engineering, IST, Technical University of Lisbon, Av. Rovisco Pais, P-1049-001 Lisbon, Portugal
| | - Wolfgang Huber
- EMBL - European Bioinformatics Institute, Cambridge CB10 1SD, UK
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250
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Sicklick JK, Li YX, Jayaraman A, Kannangai R, Qi Y, Vivekanandan P, Ludlow JW, Owzar K, Chen W, Torbenson MS, Diehl AM. Dysregulation of the Hedgehog pathway in human hepatocarcinogenesis. Carcinogenesis 2005; 27:748-57. [PMID: 16339184 DOI: 10.1093/carcin/bgi292] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hedgehog (Hh) pathway activation promotes tumors in several endodermally derived tissues, but its role in the pathogenesis of hepatocellular carcinoma (HCC) is unknown. Although normal hepatocytes lack Hh signaling, activation of the Hh pathway in endodermal progenitors is required for liver development. Thus, we hypothesized that hepatocarcinogenesis may involve regulation of Hh signaling. This pathway is activated when Hh ligand binds to its receptor, Patched (PTC). In an unoccupied state, PTC normally functions as a tumor suppressor that inhibits Smoothened (SMO), a proto-oncoprotein, from activating downstream components and transcription of target genes. Here we show that in HCCs, overexpression of the Smo proto-oncogene, as well as an increase in the stoichiometric ratio of Smo to Ptc mRNA levels, correlated with tumor size, a prognostic indicator in HCC biology. In one tumor we identified a novel Smo mutation in an evolutionarily conserved residue. We also demonstrated that HCC cell lines (HepG2 and Hep3B) expressed Hh pathway components and activated Hh transcriptional targets. In Hep3B cells, cyclopamine, an inhibitor of wild-type SMO, had no effect, but KAAD-cyclopamine, a blocker of oncogenic SMO, inhibited Hh signaling activity by 50%, decreased expression of the hepatocarcinogenic oncogene, c-myc, by 8-fold, and inhibited the growth rate of Hep3B cells by 94%. These data support our hypothesis that Hh signaling is dysregulated in human hepatocarcinogenesis. We demonstrate that overexpression and/or tumorigenic activation of the Smo proto-oncogene mediates c-myc overexpression which plays a critical role in hepatocarcinogenesis and suggests that Smo is a prognostic factor in HCC tumorigenesis.
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Affiliation(s)
- Jason K Sicklick
- Department of Surgery and Division of Surgical Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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