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Schweibenz CK, Placentra VC, Moberg KH. The Drosophila EcR-Hippo component Taiman promotes epithelial cell fitness by control of the Dally-like glypican and Wg gradient. bioRxiv 2024:2024.03.31.587486. [PMID: 38617327 PMCID: PMC11014482 DOI: 10.1101/2024.03.31.587486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Rapidly dividing cells can eliminate slow growing neighbors through the apoptotic process of cell competition. This process ensures that only high fitness cells populate embryonic tissues and is proposed to underlie the ability of oncogene-transformed cells to progressively replace normal cells within a tissue. Patches of cells in the Drosophila wing disc overexpressing the oncogenic Taiman (Tai) transcriptional coactivator kill normal neighbors by secreting Spätzle ligands that trigger pro-apoptotic Toll signaling in receiving cells. However, extracellular signaling mechanisms responsible for elimination of slow growing cells by normal neighbors remain poorly defined. Here we show that slow growing cells with reduced Tai (Tailow) are killed by normal neighbors through a mechanism involving competition for the Wingless (Wg/Wnt) ligand. Elevated Wg signaling significantly rescues elimination of Tailow cells in multiple organs, suggesting that Tai may normally promote Wg activity. Examining distribution of Wg components reveals that Tai promotes extracellular spread of the Wg ligand from source cells across the wing disc, thus ensuring patterned expression of multiple Wg-regulated target genes. Tai controls Wg spread indirectly through the extracellular glypican Dally-like protein (Dlp), which binds Wg and promotes its extracellular diffusion and capture by receptors. Data indicate that Tai likely controls Dlp at two levels: transcription of dlp mRNA and Dlp intracellular trafficking. Overall, these data indicate that the Tai acts through Dlp to enable Wg transport and signaling, and that cell competition in the Tailow model arises due to inequity in the ability of epithelial cells to sequester limiting amounts of the Wg growth factor.
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Affiliation(s)
- Colby K. Schweibenz
- Department of Cell Biology, Emory University School of Medicine
- Graduate Program in Biochemistry, Cell, and Developmental Biology
| | - Victoria C. Placentra
- Department of Cell Biology, Emory University School of Medicine
- Graduate Program in Genetics and Molecular Biology, Emory University
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2
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Hailstock T, Terry D, Wardwell-Ozgo J, Robinson BV, Moberg KH, Lerit DA. Colorimetric Synchronization of Drosophila Larvae. Curr Protoc 2023; 3:e924. [PMID: 37861353 PMCID: PMC10608261 DOI: 10.1002/cpz1.924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
The rapid succession of events during development poses an inherent challenge to achieve precise synchronization required for rigorous, quantitative phenotypic and genotypic analyses in multicellular model organisms. Drosophila melanogaster is an indispensable model for studying the development and function of higher order organisms due to extensive genome homology, tractability, and its relatively short lifespan. Presently, nine Nobel prizes serve as a testament to the utility of this elegant model system. Ongoing advancements in genetic and molecular tools allow for the underlying mechanisms of human disease to be investigated in Drosophila. However, the absence of a method to precisely age-match tissues during larval development prevents further capitalization of this powerful model organism. Drosophila spends nearly half of its life cycle progressing through three morphologically distinct larval instar stages, during which the imaginal discs, precursors of mature adult external structures (e.g., eyes, legs, wings), grow and develop distinct cell fates. Other tissues, such as the central nervous system, undergo massive morphological changes during larval development. While these three larval stages and subsequent pupal stages have historically been identified based on the number of hours post egg-laying under standard laboratory conditions, a reproducible, efficient, and inexpensive method is required to accurately age-match larvae within the third instar. The third instar stage is of particular interest, as this developmental stage spans a 48-hr window during which larval tissues switch from proliferative to differentiation programs. Moreover, some genetic manipulations can lead to developmental delays, further compounding the need for precise age-matching between control and experimental samples. This article provides a protocol optimized for synchronous staging of Drosophila third instar larvae by colorimetric characterization and is useful for age-matching a variety of tissues for numerous downstream applications. We also provide a brief discussion of the technical challenges associated with successful application of this protocol. © 2023 Wiley Periodicals LLC. Basic Protocol: Synchronization of third instar Drosophila larvae.
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Affiliation(s)
- Taylor Hailstock
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
| | - Douglas Terry
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
| | - Joanna Wardwell-Ozgo
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
- equal contributors
- Kennesaw State University, College of Science and Maths, Department of Molecular and Cellular Biology, 370 Paulding Avenue Kennesaw, GA 30144
| | - Beverly V. Robinson
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
| | - Kenneth H. Moberg
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
| | - Dorothy A. Lerit
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA 30322
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3
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Zhao H, Moberg KH, Veraksa A. Hippo pathway and Bonus control developmental cell fate decisions in the Drosophila eye. Dev Cell 2023; 58:416-434.e12. [PMID: 36868234 PMCID: PMC10023510 DOI: 10.1016/j.devcel.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 08/10/2022] [Accepted: 02/06/2023] [Indexed: 03/05/2023]
Abstract
The canonical function of the Hippo signaling pathway is the regulation of organ growth. How this pathway controls cell-fate determination is less well understood. Here, we identify a function of the Hippo pathway in cell-fate decisions in the developing Drosophila eye, exerted through the interaction of Yorkie (Yki) with the transcriptional regulator Bonus (Bon), an ortholog of mammalian transcriptional intermediary factor 1/tripartite motif (TIF1/TRIM) family proteins. Instead of controlling tissue growth, Yki and Bon promote epidermal and antennal fates at the expense of the eye fate. Proteomic, transcriptomic, and genetic analyses reveal that Yki and Bon control these cell-fate decisions by recruiting transcriptional and post-transcriptional co-regulators and by repressing Notch target genes and activating epidermal differentiation genes. Our work expands the range of functions and regulatory mechanisms under Hippo pathway control.
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Affiliation(s)
- Heya Zhao
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Alexey Veraksa
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA.
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4
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Corgiat EB, List SM, Rounds JC, Yu D, Chen P, Corbett AH, Moberg KH. The Nab2 RNA-binding protein patterns dendritic and axonal projections through a planar cell polarity-sensitive mechanism. G3 (Bethesda) 2022; 12:jkac100. [PMID: 35471546 PMCID: PMC9157165 DOI: 10.1093/g3journal/jkac100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/19/2022] [Indexed: 11/15/2022]
Abstract
RNA-binding proteins support neurodevelopment by modulating numerous steps in post-transcriptional regulation, including splicing, export, translation, and turnover of mRNAs that can traffic into axons and dendrites. One such RNA-binding protein is ZC3H14, which is lost in an inherited intellectual disability. The Drosophila melanogaster ZC3H14 ortholog, Nab2, localizes to neuronal nuclei and cytoplasmic ribonucleoprotein granules and is required for olfactory memory and proper axon projection into brain mushroom bodies. Nab2 can act as a translational repressor in conjunction with the Fragile-X mental retardation protein homolog Fmr1 and shares target RNAs with the Fmr1-interacting RNA-binding protein Ataxin-2. However, neuronal signaling pathways regulated by Nab2 and their potential roles outside of mushroom body axons remain undefined. Here, we present an analysis of a brain proteomic dataset that indicates that multiple planar cell polarity proteins are affected by Nab2 loss, and couple this with genetic data that demonstrate that Nab2 has a previously unappreciated role in restricting the growth and branching of dendrites that elaborate from larval body-wall sensory neurons. Further analysis confirms that Nab2 loss sensitizes sensory dendrites to the genetic dose of planar cell polarity components and that Nab2-planar cell polarity genetic interactions are also observed during Nab2-dependent control of axon projection in the central nervous system mushroom bodies. Collectively, these data identify the conserved Nab2 RNA-binding protein as a likely component of post-transcriptional mechanisms that limit dendrite growth and branching in Drosophila sensory neurons and genetically link this role to the planar cell polarity pathway. Given that mammalian ZC3H14 localizes to dendritic spines and controls spine density in hippocampal neurons, these Nab2-planar cell polarity genetic data may highlight a conserved path through which Nab2/ZC3H14 loss affects morphogenesis of both axons and dendrites in diverse species.
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Affiliation(s)
- Edwin B Corgiat
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA
- Department of Biology, Emory University, Atlanta, GA 30322, USA
- Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA 30322, USA
| | - Sara M List
- Neuroscience Graduate Program, Emory University, Atlanta, GA 30322, USA
| | - J Christopher Rounds
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA
- Department of Biology, Emory University, Atlanta, GA 30322, USA
- Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA 30322, USA
| | - Dehong Yu
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Ping Chen
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA
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5
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Rounds JC, Corgiat EB, Ye C, Behnke JA, Kelly SM, Corbett AH, Moberg KH. The disease-associated proteins Drosophila Nab2 and Ataxin-2 interact with shared RNAs and coregulate neuronal morphology. Genetics 2022; 220:iyab175. [PMID: 34791182 PMCID: PMC8733473 DOI: 10.1093/genetics/iyab175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 09/27/2021] [Indexed: 01/05/2023] Open
Abstract
Nab2 encodes the Drosophila melanogaster member of a conserved family of zinc finger polyadenosine RNA-binding proteins (RBPs) linked to multiple steps in post-transcriptional regulation. Mutation of the Nab2 human ortholog ZC3H14 gives rise to an autosomal recessive intellectual disability but understanding of Nab2/ZC3H14 function in metazoan nervous systems is limited, in part because no comprehensive identification of metazoan Nab2/ZC3H14-associated RNA transcripts has yet been conducted. Moreover, many Nab2/ZC3H14 functional protein partnerships remain unidentified. Here, we present evidence that Nab2 genetically interacts with Ataxin-2 (Atx2), which encodes a neuronal translational regulator, and that these factors coordinately regulate neuronal morphology, circadian behavior, and adult viability. We then present the first high-throughput identifications of Nab2- and Atx2-associated RNAs in Drosophila brain neurons using RNA immunoprecipitation-sequencing (RIP-Seq). Critically, the RNA interactomes of each RBP overlap, and Nab2 exhibits high specificity in its RNA associations in neurons in vivo, associating with a small fraction of all polyadenylated RNAs. The identities of shared associated transcripts (e.g., drk, me31B, stai) and of transcripts specific to Nab2 or Atx2 (e.g., Arpc2 and tea) promise insight into neuronal functions of, and genetic interactions between, each RBP. Consistent with prior biochemical studies, Nab2-associated neuronal RNAs are overrepresented for internal A-rich motifs, suggesting these sequences may partially mediate Nab2 target selection. These data support a model where Nab2 functionally opposes Atx2 in neurons, demonstrate Nab2 shares associated neuronal RNAs with Atx2, and reveal Drosophila Nab2 associates with a more specific subset of polyadenylated mRNAs than its polyadenosine affinity alone may suggest.
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Affiliation(s)
- J Christopher Rounds
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Edwin B Corgiat
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Changtian Ye
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Joseph A Behnke
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Seth M Kelly
- Department of Biology, The College of Wooster, Wooster, OH 44691, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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6
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Abstract
Drosophila melanogaster is an excellent model organism to study neurodegeneration. Assessing evident neurodegeneration within the fly brain involves the laborious preparation of thin-sectioned H&E-stained heads to visualize brain vacuole degeneration. Here, we present an advanced microscopy-based protocol, without the need for sectioning, to detect vacuole degeneration within whole fly brains by applying commonly used stains to reveal the brain parenchyma. This approach preserves the whole-brain architecture and enables rapid, reproducible, and quantitative analyses of vacuole-like degeneration associated with specific brain regions. For complete details on the use and execution of this protocol, please refer to Behnke et al. (2021).
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Affiliation(s)
- Joseph A Behnke
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Changtian Ye
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - James Q Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
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7
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Corgiat EB, List SM, Rounds JC, Corbett AH, Moberg KH. The RNA-binding protein Nab2 regulates the proteome of the developing Drosophila brain. J Biol Chem 2021; 297:100877. [PMID: 34139237 PMCID: PMC8260979 DOI: 10.1016/j.jbc.2021.100877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 06/07/2021] [Accepted: 06/13/2021] [Indexed: 12/14/2022] Open
Abstract
The human ZC3H14 gene, which encodes a ubiquitously expressed polyadenosine zinc finger RNA-binding protein, is mutated in an inherited form of autosomal recessive, nonsyndromic intellectual disability. To gain insight into neurological functions of ZC3H14, we previously developed a Drosophila melanogaster model of ZC3H14 loss by deleting the fly ortholog, Nab2. Studies in this invertebrate model revealed that Nab2 controls final patterns of neuron projection within fully developed adult brains, but the role of Nab2 during development of the Drosophila brain is not known. Here, we identify roles for Nab2 in controlling the dynamic growth of axons in the developing brain mushroom bodies, which support olfactory learning and memory, and regulating abundance of a small fraction of the total brain proteome. The group of Nab2-regulated brain proteins, identified by quantitative proteomic analysis, includes the microtubule-binding protein Futsch, the neuronal Ig-family transmembrane protein turtle, the glial:neuron adhesion protein contactin, the Rac GTPase-activating protein tumbleweed, and the planar cell polarity factor Van Gogh, which collectively link Nab2 to the processes of brain morphogenesis, neuroblast proliferation, circadian sleep/wake cycles, and synaptic development. Overall, these data indicate that Nab2 controls the abundance of a subset of brain proteins during the active process of wiring the pupal brain mushroom body and thus provide a window into potentially conserved functions of the Nab2/ZC3H14 RNA-binding proteins in neurodevelopment.
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Affiliation(s)
- Edwin B Corgiat
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, Georgia, USA; Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia, USA; Department of Biology, Emory University, Atlanta, Georgia, USA
| | - Sara M List
- Graduate Program in Neuroscience, Emory University, Atlanta, Georgia, USA
| | - J Christopher Rounds
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, Georgia, USA; Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia, USA; Department of Biology, Emory University, Atlanta, Georgia, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, Georgia, USA.
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, Georgia, USA.
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8
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Behnke JA, Ye C, Setty A, Moberg KH, Zheng JQ. Repetitive mild head trauma induces activity mediated lifelong brain deficits in a novel Drosophila model. Sci Rep 2021; 11:9738. [PMID: 33958652 PMCID: PMC8102574 DOI: 10.1038/s41598-021-89121-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/21/2021] [Indexed: 02/08/2023] Open
Abstract
Mild head trauma, including concussion, can lead to chronic brain dysfunction and degeneration but the underlying mechanisms remain poorly understood. Here, we developed a novel head impact system to investigate the long-term effects of mild head trauma on brain structure and function, as well as the underlying mechanisms in Drosophila melanogaster. We find that Drosophila subjected to repetitive head impacts develop long-term deficits, including impaired startle-induced climbing, progressive brain degeneration, and shortened lifespan, all of which are substantially exacerbated in female flies. Interestingly, head impacts elicit an elevation in neuronal activity and its acute suppression abrogates the detrimental effects in female flies. Together, our findings validate Drosophila as a suitable model system for investigating the long-term effects of mild head trauma, suggest an increased vulnerability to brain injury in female flies, and indicate that early altered neuronal excitability may be a key mechanism linking mild brain trauma to chronic degeneration.
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Affiliation(s)
- Joseph A Behnke
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Changtian Ye
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Aayush Setty
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - James Q Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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9
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Morton DJ, Jalloh B, Kim L, Kremsky I, Nair RJ, Nguyen KB, Rounds JC, Sterrett MC, Brown B, Le T, Karkare MC, McGaughey KD, Sheng S, Leung SW, Fasken MB, Moberg KH, Corbett AH. A Drosophila model of Pontocerebellar Hypoplasia reveals a critical role for the RNA exosome in neurons. PLoS Genet 2020; 16:e1008901. [PMID: 32645003 PMCID: PMC7373318 DOI: 10.1371/journal.pgen.1008901] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 07/21/2020] [Accepted: 06/01/2020] [Indexed: 12/27/2022] Open
Abstract
The RNA exosome is an evolutionarily-conserved ribonuclease complex critically important for precise processing and/or complete degradation of a variety of cellular RNAs. The recent discovery that mutations in genes encoding structural RNA exosome subunits cause tissue-specific diseases makes defining the role of this complex within specific tissues critically important. Mutations in the RNA exosome component 3 (EXOSC3) gene cause Pontocerebellar Hypoplasia Type 1b (PCH1b), an autosomal recessive neurologic disorder. The majority of disease-linked mutations are missense mutations that alter evolutionarily-conserved regions of EXOSC3. The tissue-specific defects caused by these amino acid changes in EXOSC3 are challenging to understand based on current models of RNA exosome function with only limited analysis of the complex in any multicellular model in vivo. The goal of this study is to provide insight into how mutations in EXOSC3 impact the function of the RNA exosome. To assess the tissue-specific roles and requirements for the Drosophila ortholog of EXOSC3 termed Rrp40, we utilized tissue-specific RNAi drivers. Depletion of Rrp40 in different tissues reveals a general requirement for Rrp40 in the development of many tissues including the brain, but also highlight an age-dependent requirement for Rrp40 in neurons. To assess the functional consequences of the specific amino acid substitutions in EXOSC3 that cause PCH1b, we used CRISPR/Cas9 gene editing technology to generate flies that model this RNA exosome-linked disease. These flies show reduced viability; however, the surviving animals exhibit a spectrum of behavioral and morphological phenotypes. RNA-seq analysis of these Drosophila Rrp40 mutants reveals increases in the steady-state levels of specific mRNAs and ncRNAs, some of which are central to neuronal function. In particular, Arc1 mRNA, which encodes a key regulator of synaptic plasticity, is increased in the Drosophila Rrp40 mutants. Taken together, this study defines a requirement for the RNA exosome in specific tissues/cell types and provides insight into how defects in RNA exosome function caused by specific amino acid substitutions that occur in PCH1b can contribute to neuronal dysfunction.
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Affiliation(s)
- Derrick J. Morton
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Binta Jalloh
- Genetics and Molecular Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Lily Kim
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Isaac Kremsky
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Rishi J. Nair
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Khuong B. Nguyen
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - J. Christopher Rounds
- Genetics and Molecular Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Maria C. Sterrett
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
- Biochemistry, Cell and Developmental Biology Graduate Program, Emory University, NE, Atlanta, Georgia, United States of America
| | - Brianna Brown
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Thalia Le
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Maya C. Karkare
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Kathryn D. McGaughey
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Shaoyi Sheng
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Sara W. Leung
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Milo B. Fasken
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Anita H. Corbett
- Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America
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10
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Kuang Y, Golan O, Preusse K, Cain B, Christensen CJ, Salomone J, Campbell I, Okwubido-Williams FV, Hass MR, Yuan Z, Eafergan N, Moberg KH, Kovall RA, Kopan R, Sprinzak D, Gebelein B. Enhancer architecture sensitizes cell specific responses to Notch gene dose via a bind and discard mechanism. eLife 2020; 9:53659. [PMID: 32297857 PMCID: PMC7213981 DOI: 10.7554/elife.53659] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 04/15/2020] [Indexed: 11/13/2022] Open
Abstract
Notch pathway haploinsufficiency can cause severe developmental syndromes with highly variable penetrance. Currently, we have a limited mechanistic understanding of phenotype variability due to gene dosage. Here, we unexpectedly found that inserting an enhancer containing pioneer transcription factor sites coupled to Notch dimer sites can induce a subset of Notch haploinsufficiency phenotypes in Drosophila with wild type Notch gene dose. Using Drosophila genetics, we show that this enhancer induces Notch phenotypes in a Cdk8-dependent, transcription-independent manner. We further combined mathematical modeling with quantitative trait and expression analysis to build a model that describes how changes in Notch signal production versus degradation differentially impact cellular outcomes that require long versus short signal duration. Altogether, these findings support a 'bind and discard' mechanism in which enhancers with specific binding sites promote rapid Cdk8-dependent Notch turnover, and thereby reduce Notch-dependent transcription at other loci and sensitize tissues to gene dose based upon signal duration.
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Affiliation(s)
- Yi Kuang
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, United States
| | - Ohad Golan
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Kristina Preusse
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, United States
| | - Brittany Cain
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, United States
| | - Collin J Christensen
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, United States
| | - Joseph Salomone
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, United States.,Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, United States
| | - Ian Campbell
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, United States
| | | | - Matthew R Hass
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, United States
| | - Zhenyu Yuan
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, United States
| | - Nathanel Eafergan
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, United States
| | - Rhett A Kovall
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, United States
| | - Raphael Kopan
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, United States
| | - David Sprinzak
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Science, Tel Aviv University, Tel Aviv, Israel
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, United States
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11
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Kim H, Lim J, Bao H, Jiao B, Canon SM, Epstein MP, Xu K, Jiang J, Parameswaran J, Li Y, Moberg KH, Landers JE, Fournier C, Allen EG, Glass JD, Wingo TS, Jin P. Rare variants in MYH15 modify amyotrophic lateral sclerosis risk. Hum Mol Genet 2019; 28:2309-2318. [PMID: 30985904 PMCID: PMC6606848 DOI: 10.1093/hmg/ddz063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 03/14/2019] [Accepted: 03/21/2019] [Indexed: 11/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive muscular atrophy and respiratory failure. The G4C2 repeat expansion in the C9orf72 gene is the most prevalent genetic risk for ALS. Mutation carriers (C9ALS) display variability in phenotypes such as age-at-onset and duration, suggesting the existence of additional genetic factors. Here we introduce a three-step gene discovery strategy to identify genetic factors modifying the risk of both C9ALS and sporadic ALS (sALS) using limited samples. We first identified 135 candidate genetic modifiers of C9ALS using whole-genome sequencing (WGS) of extreme C9ALS cases diagnosed ~30 years apart. We then performed an unbiased genetic screen using a Drosophila model of the G4C2 repeat expansion with the genes identified from WGS analysis. This genetic screen identified the novel genetic interaction between G4C2 repeat-associated toxicity and 18 genetic factors, suggesting their potential association with C9ALS risk. We went on to test if 14 out of the 18 genes, those which were not known to be risk factors for ALS previously, are also associated with ALS risk in sALS cases. Gene-based-statistical analyses of targeted resequencing and WGS were performed. These analyses together reveal that rare variants in MYH15 represent a likely genetic risk factor for ALS. Furthermore, we show that MYH15 could modulate the toxicity of dipeptides produced from expanded G4C2 repeat. Our study presented here demonstrates the power of combining WGS with fly genetics to facilitate the discovery of fundamental genetic components of complex traits with a limited number of samples.
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Affiliation(s)
- Hyerim Kim
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
- Cancer Biology Program, Emory University, Atlanta, GA, USA
| | - Junghwa Lim
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Han Bao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Bin Jiao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Se Min Canon
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - Michael P Epstein
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Keqin Xu
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Jie Jiang
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA, USA
| | - Janani Parameswaran
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA, USA
| | - Yingjie Li
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA, USA
| | - John E Landers
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Christina Fournier
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
- Division of Neurology, Atlanta VA Medical Center, Decatur, GA, USA
| | - Emily G Allen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Jonathan D Glass
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
| | - Thomas S Wingo
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
- Division of Neurology, Atlanta VA Medical Center, Decatur, GA, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
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12
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Yao B, Li Y, Wang Z, Chen L, Poidevin M, Zhang C, Lin L, Wang F, Bao H, Jiao B, Lim J, Cheng Y, Huang L, Phillips BL, Xu T, Duan R, Moberg KH, Wu H, Jin P. Active N 6-Methyladenine Demethylation by DMAD Regulates Gene Expression by Coordinating with Polycomb Protein in Neurons. Mol Cell 2018; 71:848-857.e6. [PMID: 30078725 DOI: 10.1016/j.molcel.2018.07.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 06/05/2018] [Accepted: 07/03/2018] [Indexed: 12/22/2022]
Abstract
A ten-eleven translocation (TET) ortholog exists as a DNA N6-methyladenine (6mA) demethylase (DMAD) in Drosophila. However, the molecular roles of 6mA and DMAD remain unexplored. Through genome-wide 6mA and transcriptome profiling in Drosophila brains and neuronal cells, we found that 6mA may epigenetically regulate a group of genes involved in neurodevelopment and neuronal functions. Mechanistically, DMAD interacts with the Trithorax-related complex protein Wds to maintain active transcription by dynamically demethylating intragenic 6mA. Accumulation of 6mA by depleting DMAD coordinates with Polycomb proteins and contributes to transcriptional repression of these genes. Our findings suggest that active 6mA demethylation by DMAD plays essential roles in fly CNS by orchestrating through added epigenetic mechanisms.
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Affiliation(s)
- Bing Yao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Yujing Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Zhiqin Wang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Li Chen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biostatistics and Bioinformatics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mickael Poidevin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Can Zhang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Li Lin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Feng Wang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Han Bao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Bin Jiao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Junghwa Lim
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ying Cheng
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Luoxiu Huang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | - Tianlei Xu
- Department of Biostatistics and Bioinformatics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ranhui Duan
- State Key Laboratory of Medical Genetics, School of Life Science, Central South University, Changsha, Hunan 410078, China
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Hao Wu
- Department of Biostatistics and Bioinformatics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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13
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Bienkowski RS, Banerjee A, Rounds JC, Rha J, Omotade OF, Gross C, Morris KJ, Leung SW, Pak C, Jones SK, Santoro MR, Warren ST, Zheng JQ, Bassell GJ, Corbett AH, Moberg KH. The Conserved, Disease-Associated RNA Binding Protein dNab2 Interacts with the Fragile X Protein Ortholog in Drosophila Neurons. Cell Rep 2018; 20:1372-1384. [PMID: 28793261 DOI: 10.1016/j.celrep.2017.07.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/28/2017] [Accepted: 07/14/2017] [Indexed: 12/20/2022] Open
Abstract
The Drosophila dNab2 protein is an ortholog of human ZC3H14, a poly(A) RNA binding protein required for intellectual function. dNab2 supports memory and axon projection, but its molecular role in neurons is undefined. Here, we present a network of interactions that links dNab2 to cytoplasmic control of neuronal mRNAs in conjunction with the fragile X protein ortholog dFMRP. dNab2 and dfmr1 interact genetically in control of neurodevelopment and olfactory memory, and their encoded proteins co-localize in puncta within neuronal processes. dNab2 regulates CaMKII, but not futsch, implying a selective role in control of dFMRP-bound transcripts. Reciprocally, dFMRP and vertebrate FMRP restrict mRNA poly(A) tail length, similar to dNab2/ZC3H14. Parallel studies of murine hippocampal neurons indicate that ZC3H14 is also a cytoplasmic regulator of neuronal mRNAs. Altogether, these findings suggest that dNab2 represses expression of a subset of dFMRP-target mRNAs, which could underlie brain-specific defects in patients lacking ZC3H14.
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Affiliation(s)
- Rick S Bienkowski
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ayan Banerjee
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - J Christopher Rounds
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jennifer Rha
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Omotola F Omotade
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Christina Gross
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Kevin J Morris
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Sara W Leung
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - ChangHui Pak
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Stephanie K Jones
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Michael R Santoro
- Department of Human Genetics, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Stephen T Warren
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Human Genetics, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Pediatrics, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - James Q Zheng
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA.
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14
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Rha J, Jones SK, Fidler J, Banerjee A, Leung SW, Morris KJ, Wong JC, Inglis GAS, Shapiro L, Deng Q, Cutler AA, Hanif AM, Pardue MT, Schaffer A, Seyfried NT, Moberg KH, Bassell GJ, Escayg A, García PS, Corbett AH. The RNA-binding protein, ZC3H14, is required for proper poly(A) tail length control, expression of synaptic proteins, and brain function in mice. Hum Mol Genet 2018; 26:3663-3681. [PMID: 28666327 DOI: 10.1093/hmg/ddx248] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 06/20/2017] [Indexed: 12/30/2022] Open
Abstract
A number of mutations in genes that encode ubiquitously expressed RNA-binding proteins cause tissue specific disease. Many of these diseases are neurological in nature revealing critical roles for this class of proteins in the brain. We recently identified mutations in a gene that encodes a ubiquitously expressed polyadenosine RNA-binding protein, ZC3H14 (Zinc finger CysCysCysHis domain-containing protein 14), that cause a nonsyndromic, autosomal recessive form of intellectual disability. This finding reveals the molecular basis for disease and provides evidence that ZC3H14 is essential for proper brain function. To investigate the role of ZC3H14 in the mammalian brain, we generated a mouse in which the first common exon of the ZC3H14 gene, exon 13 is removed (Zc3h14Δex13/Δex13) leading to a truncated ZC3H14 protein. We report here that, as in the patients, Zc3h14 is not essential in mice. Utilizing these Zc3h14Δex13/Δex13mice, we provide the first in vivo functional characterization of ZC3H14 as a regulator of RNA poly(A) tail length. The Zc3h14Δex13/Δex13 mice show enlarged lateral ventricles in the brain as well as impaired working memory. Proteomic analysis comparing the hippocampi of Zc3h14+/+ and Zc3h14Δex13/Δex13 mice reveals dysregulation of several pathways that are important for proper brain function and thus sheds light onto which pathways are most affected by the loss of ZC3H14. Among the proteins increased in the hippocampi of Zc3h14Δex13/Δex13 mice compared to control are key synaptic proteins including CaMK2a. This newly generated mouse serves as a tool to study the function of ZC3H14 in vivo.
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Affiliation(s)
- Jennifer Rha
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.,Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, GA 30322, USA
| | - Stephanie K Jones
- Department of Biology.,Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA
| | - Jonathan Fidler
- Department of Anesthesiology, Emory University School of Medicine & Research Division, Atlanta VA Medical Center, Atlanta, GA 30322, USA
| | | | | | - Kevin J Morris
- Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, GA 30322, USA.,Department of Biology
| | - Jennifer C Wong
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - George Andrew S Inglis
- Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA.,Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lindsey Shapiro
- Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA.,Graduate Program in Neuroscience, Emory University, Atlanta, GA 30322, USA
| | - Qiudong Deng
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Alicia A Cutler
- Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, GA 30322, USA.,Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Adam M Hanif
- Department of Opthamology, Emory University School of Medicine & Research Division, & Atlanta VA Medical Center, Atlanta, GA 30322, USA
| | - Machelle T Pardue
- Department of Opthamology, Emory University School of Medicine & Research Division, & Atlanta VA Medical Center, Atlanta, GA 30322, USA
| | - Ashleigh Schaffer
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4955, USA
| | - Nicholas T Seyfried
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Andrew Escayg
- Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, GA 30322, USA
| | - Paul S García
- Department of Anesthesiology, Emory University School of Medicine & Research Division, Atlanta VA Medical Center, Atlanta, GA 30322, USA
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15
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Zhang C, Robinson BS, Xu W, Yang L, Yao B, Zhao H, Byun PK, Jin P, Veraksa A, Moberg KH. The ecdysone receptor coactivator Taiman links Yorkie to transcriptional control of germline stem cell factors in somatic tissue. Dev Cell 2015; 34:168-80. [PMID: 26143992 DOI: 10.1016/j.devcel.2015.05.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Revised: 04/25/2015] [Accepted: 05/14/2015] [Indexed: 12/16/2022]
Abstract
The Hippo pathway is a conserved signaling cascade that modulates tissue growth. Although its core elements are well defined, factors modulating Hippo transcriptional outputs remain elusive. Here we show that components of the steroid-responsive ecdysone (Ec) pathway modulate Hippo transcriptional effects in imaginal disc cells. The Ec receptor coactivator Taiman (Tai) interacts with the Hippo transcriptional coactivator Yorkie (Yki) and promotes expression of canonical Yki-responsive genes. Tai enhances Yki-driven growth, while Tai loss, or a form of Tai unable to bind Yki, suppresses Yki-driven tissue growth. This growth suppression is not correlated with impaired induction of canonical Hippo-responsive genes but with suppression of a distinct pro-growth program of Yki-induced/Tai-dependent genes, including the germline stem cell factors nanos and piwi. These data reveal Hippo/Ec pathway crosstalk in the form a Yki-Tai complex that collaboratively induces germline genes as part of a transcriptional program that is normally repressed in developing somatic epithelia.
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Affiliation(s)
- Can Zhang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Brian S Robinson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Pathology & Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Wenjian Xu
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Liu Yang
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Bing Yao
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Heya Zhao
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Phil K Byun
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; Graduate Program in Genetics and Molecular Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Alexey Veraksa
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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16
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Kelly SM, Bienkowski R, Banerjee A, Melicharek DJ, Brewer ZA, Marenda DR, Corbett AH, Moberg KH. The Drosophila ortholog of the Zc3h14 RNA binding protein acts within neurons to pattern axon projection in the developing brain. Dev Neurobiol 2015; 76:93-106. [PMID: 25980665 DOI: 10.1002/dneu.22301] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 12/18/2022]
Abstract
The dNab2 polyadenosine RNA binding protein is the D. melanogaster ortholog of the vertebrate ZC3H14 protein, which is lost in a form of inherited intellectual disability (ID). Human ZC3H14 can rescue D. melanogaster dNab2 mutant phenotypes when expressed in all neurons of the developing nervous system, suggesting that dNab2/ZC3H14 performs well-conserved roles in neurons. However, the cellular and molecular requirements for dNab2/ZC3H14 in the developing nervous system have not been defined in any organism. Here we show that dNab2 is autonomously required within neurons to pattern axon projection from Kenyon neurons into the mushroom bodies, which are required for associative olfactory learning and memory in insects. Mushroom body axons lacking dNab2 project aberrantly across the brain midline and also show evidence of defective branching. Coupled with the prior finding that ZC3H14 is highly expressed in rodent hippocampal neurons, this requirement for dNab2 in mushroom body neurons suggests that dNab2/ZC3H14 has a conserved role in supporting axon projection and branching. Consistent with this idea, loss of dNab2 impairs short-term memory in a courtship conditioning assay. Taken together these results reveal a cell-autonomous requirement for the dNab2 RNA binding protein in mushroom body development and provide a window into potential neurodevelopmental functions of the human ZC3H14 protein.
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Affiliation(s)
- Seth M Kelly
- Department of Biology, College of Wooster, Wooster, Ohio, 44691
| | - Rick Bienkowski
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322.,Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322.,Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia, 30322
| | - Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - David J Melicharek
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | | | - Daniel R Marenda
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104.,Departments of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322
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17
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Zhang C, Casas-Tintó S, Li G, Lin N, Chung M, Moreno E, Moberg KH, Zhou L. An intergenic regulatory region mediates Drosophila Myc-induced apoptosis and blocks tissue hyperplasia. Oncogene 2015; 34:2412. [PMID: 25924716 DOI: 10.1038/onc.2014.463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Zhang C, Casas-Tintó S, Li G, Lin N, Chung M, Moreno E, Moberg KH, Zhou L. An intergenic regulatory region mediates Drosophila Myc-induced apoptosis and blocks tissue hyperplasia. Oncogene 2014; 34:2385-97. [PMID: 24931167 PMCID: PMC4268096 DOI: 10.1038/onc.2014.160] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 12/31/2022]
Abstract
Induction of cell-autonomous apoptosis following oncogene-induced overproliferation is a major tumor-suppressive mechanism in vertebrates. However, the detailed mechanism mediating this process remains enigmatic. In this study, we demonstrate that dMyc-induced cell-autonomous apoptosis in the fruit fly Drosophila melanogaster relies on an intergenic sequence termed the IRER (irradiation-responsive enhancer region). The IRER mediates the expression of surrounding proapoptotic genes, and we use an in vivo reporter of the IRER chromatin state to gather evidence that epigenetic control of DNA accessibility within the IRER is an important determinant of the strength of this response to excess dMyc. In a previous work, we showed that the IRER also mediates P53-dependent induction of proapoptotic genes following DNA damage, and the chromatin conformation within IRER is regulated by polycomb group-mediated histone modifications. dMyc-induced apoptosis and the P53-mediated DNA damage response thus overlap in a requirement for the IRER. The epigenetic mechanisms controlling IRER accessibility appear to set thresholds for the P53- and dMyc-induced expression of apoptotic genes in vivo and may have a profound impact on cellular sensitivity to oncogene-induced stress.
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Affiliation(s)
- C Zhang
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - S Casas-Tintó
- Cajal Institute, Spanish Research Council (CSIC), Madrid, Spain
| | - G Li
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] UF Genetics Institute, University of Florida, Gainesville, FL, USA
| | - N Lin
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA
| | - M Chung
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA
| | - E Moreno
- Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - K H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - L Zhou
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] UF Genetics Institute, University of Florida, Gainesville, FL, USA
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19
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Kelly SM, Leung SW, Pak C, Banerjee A, Moberg KH, Corbett AH. A conserved role for the zinc finger polyadenosine RNA binding protein, ZC3H14, in control of poly(A) tail length. RNA 2014; 20:681-688. [PMID: 24671764 PMCID: PMC3988569 DOI: 10.1261/rna.043984.113] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 02/10/2014] [Indexed: 06/03/2023]
Abstract
The ZC3H14 gene, which encodes a ubiquitously expressed, evolutionarily conserved, nuclear, zinc finger polyadenosine RNA-binding protein, was recently linked to autosomal recessive, nonsyndromic intellectual disability. Although studies have been carried out to examine the function of putative orthologs of ZC3H14 in Saccharomyces cerevisiae, where the protein is termed Nab2, and Drosophila, where the protein has been designated dNab2, little is known about the function of mammalian ZC3H14. Work from both budding yeast and flies implicates Nab2/dNab2 in poly(A) tail length control, while a role in poly(A) RNA export from the nucleus has been reported only for budding yeast. Here we provide the first functional characterization of ZC3H14. Analysis of ZC3H14 function in a neuronal cell line as well as in vivo complementation studies in a Drosophila model identify a role for ZC3H14 in proper control of poly(A) tail length in neuronal cells. Furthermore, we show here that human ZC3H14 can functionally substitute for dNab2 in fly neurons and can rescue defects in development and locomotion that are present in dNab2 null flies. These rescue experiments provide evidence that this zinc finger-containing class of nuclear polyadenosine RNA-binding proteins plays an evolutionarily conserved role in controlling the length of the poly(A) tail in neurons.
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Affiliation(s)
- Seth M. Kelly
- Department of Biology, College of Wooster, Wooster, Ohio 44691, USA
| | - Sara W. Leung
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - ChangHui Pak
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Anita H. Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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20
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Mortimer NT, Moberg KH. The archipelago ubiquitin ligase subunit acts in target tissue to restrict tracheal terminal cell branching and hypoxic-induced gene expression. PLoS Genet 2013; 9:e1003314. [PMID: 23459416 PMCID: PMC3573119 DOI: 10.1371/journal.pgen.1003314] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/22/2012] [Indexed: 12/20/2022] Open
Abstract
The Drosophila melanogaster gene archipelago (ago) encodes the F-box/WD-repeat protein substrate specificity factor for an SCF (Skp/Cullin/F-box)-type polyubiquitin ligase that inhibits tumor-like growth by targeting proteins for degradation by the proteasome. The Ago protein is expressed widely in the fly embryo and larva and promotes degradation of pro-proliferative proteins in mitotically active cells. However the requirement for Ago in post-mitotic developmental processes remains largely unexplored. Here we show that Ago is an antagonist of the physiologic response to low oxygen (hypoxia). Reducing Ago activity in larval muscle cells elicits enhanced branching of nearby tracheal terminal cells in normoxia. This tracheogenic phenotype shows a genetic dependence on sima, which encodes the HIF-1α subunit of the hypoxia-inducible transcription factor dHIF and its target the FGF ligand branchless (bnl), and is enhanced by depletion of the Drosophila Von Hippel Lindau (dVHL) factor, which is a subunit of an oxygen-dependent ubiquitin ligase that degrades Sima/HIF-1α protein in metazoan cells. Genetic reduction of ago results in constitutive expression of some hypoxia-inducible genes in normoxia, increases the sensitivity of others to mild hypoxic stimulus, and enhances the ability of adult flies to recover from hypoxic stupor. As a molecular correlate to these genetic data, we find that Ago physically associates with Sima and restricts Sima levels in vivo. Collectively, these findings identify Ago as a required element of a circuit that suppresses the tracheogenic activity of larval muscle cells by antagonizing the Sima-mediated transcriptional response to hypoxia.
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Affiliation(s)
- Nathan T. Mortimer
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- ¤ Current address: Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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21
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Xu P, Tan H, Duong DM, Yang Y, Kupsco J, Moberg KH, Li H, Jin P, Peng J. Stable isotope labeling with amino acids in Drosophila for quantifying proteins and modifications. J Proteome Res 2012; 11:4403-12. [PMID: 22830426 DOI: 10.1021/pr300613c] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Drosophila melanogaster is a common animal model for genetics studies, and quantitative proteomics studies of the fly are emerging. Here, we present in detail the development of a procedure to incorporate stable isotope-labeled amino acids into the fly proteome. In the method of stable isotope labeling with amino acids in Drosophila melanogaster (SILAC fly), flies were fed with SILAC-labeled yeast grown with modified media, enabling near complete labeling in a single generation. Biological variation in the proteome among individual flies was evaluated in a series of null experiments. We further applied the SILAC fly method to profile proteins from a model of fragile X syndrome, the most common cause of inherited mental retardation in human. The analysis identified a number of altered proteins in the disease model, including actin-binding protein profilin and microtubulin-associated protein futsch. The change of both proteins was validated by immunoblotting analysis. Moreover, we extended the SILAC fly strategy to study the dynamics of protein ubiquitination during the fly life span (from day 1 to day 30), by measuring the level of ubiquitin along with two major polyubiquitin chains (K48 and K63 linkages). The results show that the abundance of protein ubiquitination and the two major linkages do not change significantly within the measured age range. Together, the data demonstrate the application of the SILAC principle in D. melanogaster, facilitating the integration of powerful fly genomics with emerging proteomics.
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Affiliation(s)
- Ping Xu
- Department of Human Genetics, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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22
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Kagey JD, Brown JA, Moberg KH. Regulation of Yorkie activity in Drosophila imaginal discs by the Hedgehog receptor gene patched. Mech Dev 2012; 129:339-49. [PMID: 22705500 DOI: 10.1016/j.mod.2012.05.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/06/2012] [Accepted: 05/10/2012] [Indexed: 12/19/2022]
Abstract
The Hedgehog (Hh) pathway was first defined by its role in segment polarity in the Drosophila melanogaster embryonic epidermis and has since been linked to many aspects of vertebrate development and disease. In humans, mutation of the Patched1 (PTCH1) gene, which encodes an inhibitor of Hh signaling, leads to tumors of the skin and pediatric brain. Despite the high level of conservation between the vertebrate and invertebrate Hh pathways, studies in Drosophila have yet to find direct evidence that ptc limits organ size. Here we report identification of Drosophila ptc in a screen for mutations that require a synergistic apoptotic block in order to drive overgrowth. Developing imaginal discs containing clones of ptc mutant cells immortalized by the concurrent loss of the Apaf-1-related killer (Ark) gene are overgrown due, in large part, to the overgrowth of wild type portions of these discs. This phenotype correlates with overexpression of the morphogen Dpp in ptc,Ark double-mutant cells, leading to elevated phosphorylation of the Dpp pathway effector Mad (p-Mad) in cells surrounding ptc,Ark mutant clones. p-Mad functions with the Hippo pathway oncoprotein Yorkie (Yki) to induce expression of the pro-growth/anti-apoptotic microRNA bantam. Accordingly, Yki activity is elevated among wild type cells surrounding ptc,Ark clones and alleles of bantam and yki dominantly suppress the enlarged-disc phenotype produced by loss of ptc. These data suggest that ptc can regulate Yki in a non-cell autonomous manner and reveal an intercellular link between the Hh and Hippo pathways that may contribute to growth-regulatory properties of the Hh pathway in development and disease.
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Affiliation(s)
- Jacob D Kagey
- Department of Biology, University of Detroit Mercy, Detroit, MI, USA.
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23
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Robinson BS, Moberg KH. Drosophila endocytic neoplastic tumor suppressor genes regulate Sav/Wts/Hpo signaling and the c-Jun N-terminal kinase pathway. Cell Cycle 2011; 10:4110-8. [PMID: 22101275 DOI: 10.4161/cc.10.23.18243] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Genetic screens in the fruit fly Drosophila melanogaster have identified a class of neoplastic tumor suppressor genes (endocytic nTSGs), which encode proteins that localize to endosomes and facilitate the trafficking of membrane-bound receptors and adhesion molecules into the degradative lysosome. Loss of endocytic nTSGs transforms imaginal disc epithelia into highly proliferative, invasive tissues that fail to differentiate and display defects in cellular apicobasal polarity, adhesion and tissue architecture. As vertebrate homologs of some Drosophila nTSGs are linked to tumor formation, identifying molecular changes in signaling associated with nTSG loss could inform understanding of neoplastic transformation in vertebrates. Here we show that mutations in genes that act at multiple steps of the endolysosomal pathway lead to autonomous activation of the Sav/Wts/Hpo (SWH) transcriptional effector Yki (YAP/TAZ in vertebrates) and the Jun N-terminal kinase (JNK), which is known to promote Yki activity in cells with disrupted polarity. Yki and JNK activity are elevated by mutations at multiple steps in the endolysosomal pathway including mutations in the AP-2σ gene, which encodes a component of the AP-2 adaptor complex that recruits cargoes into clathrin-coated pits for subsequent internalization. Moreover, reduction of JNK activity can decrease elevated Yki-signaling caused by altered endocytosis. These studies reveal a broad requirement for components of the endocytic pathway in regulating SWH and JNK outputs, and place Drosophila endocytic nTSGs into a network that involving two major signaling pathways implicated in oncogenesis.
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Affiliation(s)
- Brian S Robinson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
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24
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Abstract
Some pathogens are able to establish themselves within the host because they have evolved mechanisms to disrupt host innate immunity. For example, a number of pathogens secrete preformed effector proteins via type III secretion apparatuses that influence innate immune or apoptotic signalling pathways. One group of effector proteins that usurp innate immune signalling is the YopJ-like family of bacterial effector proteins, which includes AopP from Aeromonas salmonicida. Aeromonas species are known to cause gastrointestinal disease in humans, and are associated mainly with subcutaneous wound infections and septicaemia in other metazoans, particularly fish. AopP has been reported to have inhibitory activity against the NF-κB pathway in cultured cells, although the pathological outcomes of AopP activity have not been examined. Here, we show that AopP has potent pro-apoptotic activity when expressed in cultured mammalian macrophage or epithelial cells, or when ectopically expressed in Drosophila melanogaster haemocytes or imaginal disk epithelial cells. Furthermore, apoptosis was significantly elevated upon concurrent AopP expression and TNF-α cellular stimulation. Together, our results demonstrate how the specificity of a YopJ-like protein towards signalling pathways directly governs cellular pathological outcome in disease.
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Affiliation(s)
- Rheinallt M Jones
- Departments of Pathology and Laboratory Medicine Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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25
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Gilbert MM, Tipping M, Veraksa A, Moberg KH. A screen for conditional growth suppressor genes identifies the Drosophila homolog of HD-PTP as a regulator of the oncoprotein Yorkie. Dev Cell 2011; 20:700-12. [PMID: 21571226 DOI: 10.1016/j.devcel.2011.04.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 02/28/2011] [Accepted: 04/26/2011] [Indexed: 12/19/2022]
Abstract
Mammalian cancers depend on "multiple hits," some of which promote growth and some of which block apoptosis. We screened for mutations that require a synergistic block in apoptosis to promote tissue overgrowth and identified myopic (mop), the Drosophila homolog of the candidate tumor-suppressor and endosomal regulator His-domain protein tyrosine phosphatase (HD-PTP). We find that Myopic regulates the Salvador/Warts/Hippo (SWH) tumor suppressor pathway: Myopic PPxY motifs bind conserved residues in the WW domains of the transcriptional coactivator Yorkie, and Myopic colocalizes with Yorkie at endosomes. Myopic controls Yorkie endosomal association and protein levels, ultimately influencing expression of some Yorkie target genes. However, the antiapoptotic gene diap1 is not affected, which may explain the conditional nature of the myopic growth phenotype. These data establish Myopic as a Yorkie regulator and implicate Myopic-dependent association of Yorkie with endosomal compartments as a regulatory step in nuclear outputs of the SWH pathway.
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Affiliation(s)
- M Melissa Gilbert
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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26
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Nicholson SC, Nicolay BN, Frolov MV, Moberg KH. Notch-dependent expression of the archipelago ubiquitin ligase subunit in the Drosophila eye. Development 2010; 138:251-60. [PMID: 21148181 DOI: 10.1242/dev.054429] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
archipelago (ago)/Fbw7 encodes a conserved protein that functions as the substrate-receptor component of a polyubiquitin ligase that suppresses tissue growth in flies and tumorigenesis in vertebrates. Ago/Fbw7 targets multiple proteins for degradation, including the G1-S regulator Cyclin E and the oncoprotein dMyc/c-Myc. Despite prominent roles in growth control, little is known about the signals that regulate Ago/Fbw7 abundance in developing tissues. Here we use the Drosophila eye as a model to identify developmental signals that regulate ago expression. We find that expression of ago mRNA and protein is induced by passage of the morphogenetic furrow (MF) and identify the hedgehog (hh) and Notch (N) pathways as elements of this inductive mechanism. Cells mutant for N pathway components, or hh-defective cells that express reduced levels of the Notch ligand Delta, fail to upregulate ago transcription in the region of the MF; reciprocally, ectopic N activation in eye discs induces expression of ago mRNA. A fragment of the ago promoter that contains consensus binding sites for the N pathway transcription factor Su(H) is bound by Su(H) and confers N-inducibility in cultured cells. The failure to upregulate ago in N pathway mutant cells correlates with accumulation of the SCF-Ago target Cyclin E in the area of the MF, and this is rescued by re-expression of ago. These data suggest a model in which N acts through ago to restrict levels of the pro-mitotic factor Cyclin E. This N-Ago-Cyclin E link represents a significant new cell cycle regulatory mechanism in the developing eye.
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Affiliation(s)
- Sarah C Nicholson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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27
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Kushner RF, Ryan EL, Sefton JMI, Sanders RD, Lucioni PJ, Moberg KH, Fridovich-Keil JL. A Drosophila melanogaster model of classic galactosemia. Dis Model Mech 2010; 3:618-27. [PMID: 20519569 DOI: 10.1242/dmm.005041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Classic galactosemia is a potentially lethal disorder that results from profound impairment of galactose-1-phosphate uridylyltransferase (GALT). Despite decades of research, the underlying pathophysiology of classic galactosemia remains unclear, in part owing to the lack of an appropriate animal model. Here, we report the establishment of a Drosophila melanogaster model of classic galactosemia; this is the first whole-animal genetic model to mimic aspects of the patient phenotype. Analogous to humans, GALT-deficient D. melanogaster survive under conditions of galactose restriction, but accumulate elevated levels of galactose-1-phosphate and succumb during larval development following galactose exposure. As in patients, the potentially lethal damage is reversible if dietary galactose restriction is initiated early in life. GALT-deficient Drosophila also exhibit locomotor complications despite dietary galactose restriction, and both the acute and long-term complications can be rescued by transgenic expression of human GALT. Using this new Drosophila model, we have begun to dissect the timing, extent and mechanism(s) of galactose sensitivity in the absence of GALT activity.
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Affiliation(s)
- Rebekah F Kushner
- Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University, Atlanta, GA 30322, USA
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28
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Sanders RD, Sefton JMI, Moberg KH, Fridovich-Keil JL. UDP-galactose 4' epimerase (GALE) is essential for development of Drosophila melanogaster. Dis Model Mech 2010; 3:628-38. [PMID: 20519568 DOI: 10.1242/dmm.005058] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
UDP-galactose 4' epimerase (GALE) catalyzes the interconversion of UDP-galactose and UDP-glucose in the final step of the Leloir pathway; human GALE (hGALE) also interconverts UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine. GALE therefore plays key roles in the metabolism of dietary galactose, in the production of endogenous galactose, and in maintaining the ratios of key substrates for glycoprotein and glycolipid biosynthesis. Partial impairment of hGALE results in the potentially lethal disorder epimerase-deficiency galactosemia. We report here the generation and initial characterization of a first whole-animal model of GALE deficiency using the fruit fly Drosophila melanogaster. Our results confirm that GALE function is essential in developing animals; Drosophila lacking GALE die as embryos but are rescued by the expression of a human GALE transgene. Larvae in which GALE has been conditionally knocked down die within days of GALE loss. Conditional knockdown and transgene expression studies further demonstrate that GALE expression in the gut primordium and Malpighian tubules is both necessary and sufficient for survival. Finally, like patients with generalized epimerase deficiency galactosemia, Drosophila with partial GALE loss survive in the absence of galactose but succumb in development if exposed to dietary galactose. These data establish the utility of the fly model of GALE deficiency and set the stage for future studies to define the mechanism(s) and modifiers of outcome in epimerase deficiency galactosemia.
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Affiliation(s)
- Rebecca D Sanders
- Graduate Program in Biochemistry, Cell and Developmental Biology, Emory University, Atlanta, GA 30322, USA
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29
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Robinson BS, Huang J, Hong Y, Moberg KH. Crumbs regulates Salvador/Warts/Hippo signaling in Drosophila via the FERM-domain protein Expanded. Curr Biol 2010; 20:582-90. [PMID: 20362445 PMCID: PMC2855393 DOI: 10.1016/j.cub.2010.03.019] [Citation(s) in RCA: 264] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 03/11/2010] [Accepted: 03/11/2010] [Indexed: 01/15/2023]
Abstract
BACKGROUND Altered expression of apicobasal polarity factors is associated with cancer in vertebrates and tissue overgrowth in invertebrates, yet the mechanisms by which these factors affect growth-regulatory pathways are not well defined. We have tested the basis of an overgrowth phenotype driven by the Drosophila protein Crumbs (Crb), which nucleates an apical membrane complex that functionally interacts with the Par6/Par3/aPKC and Scrib/Dlg/Lgl apicobasal polarity complexes. RESULTS We find that Crb-driven growth is dependent upon the Salvador/Warts/Hippo (SWH) pathway and its transcriptional effector Yorkie (Yki). Expression of the Crb intracellular domain elevates Yki activity, and this correlates in tissues and cultured cells with loss of Expanded (Ex), an apically localized SWH component that inhibits Yki. Reciprocally, loss of crb elevates Ex levels, although this excess Ex does not concentrate to its normal location at apical junctions. The Ex-regulatory domain of Crb maps to the juxtamembrane FERM-binding motif (JM), a cytoskeletal interaction domain distinct from the PDZ-binding motif (PBM) through which Crb binds polarity factors. Expression of Crb-JM drives Yki activity and organ growth with little effect on tissue architecture, while Crb-PBM reciprocally produces tissue architectural defects without significant effect on Yki activity. CONCLUSIONS These studies identify Crb as a novel SWH regulator via JM-dependent effects on Ex levels and localization and suggest that discrete domains within Crb may allow it to integrate junctional polarity signals with a conserved growth pathway.
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Affiliation(s)
- Brian S. Robinson
- Department of Cell Biology, Emory University School of Medicine Atlanta, GA
| | - Juang Huang
- Department of Cell Biology and Physiology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Yang Hong
- Department of Cell Biology and Physiology, University of Pittsburgh Medical School, Pittsburgh, PA
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine Atlanta, GA
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30
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Gilbert MM, Robinson BS, Moberg KH. Functional interactions between the erupted/tsg101 growth suppressor gene and the DaPKC and rbf1 genes in Drosophila imaginal disc tumors. PLoS One 2009; 4:e7039. [PMID: 19855819 PMCID: PMC2739425 DOI: 10.1371/journal.pone.0007039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 08/19/2009] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The Drosophila gene erupted (ept) encodes the fly homolog of human Tumor Susceptibility Gene-101 (TSG101), which functions as part of the conserved ESCRT-1 complex to facilitate the movement of cargoes through the endolysosomal pathway. Loss of ept or other genes that encode components of the endocytic machinery (e.g. synatxin7/avalanche, rab5, and vps25) produces disorganized overgrowth of imaginal disc tissue. Excess cell division is postulated to be a primary cause of these 'neoplastic' phenotypes, but the autonomous effect of these mutations on cell cycle control has not been examined. PRINCIPAL FINDINGS Here we show that disc cells lacking ept function display an altered cell cycle profile indicative of deregulated progression through the G1-to-S phase transition and express reduced levels of the tumor suppressor ortholog and G1/S inhibitor Rbf1. Genetic reductions of the Drosophila aPKC kinase (DaPKC), which has been shown to promote tumor growth in other fly tumor models, prevent both the ept neoplastic phenotype and the reduction in Rbf1 levels that otherwise occurs in clones of ept mutant cells; this effect is coincident with changes in localization of Notch and Crumbs, two proteins whose sorting is altered in ept mutant cells. The effect on Rbf1 can also be blocked by removal of the gamma-secretase component presenilin, suggesting that cleavage of a gamma-secretase target influences Rbf1 levels in ept mutant cells. Expression of exogenous rbf1 completely ablates ept mutant eye tissues but only mildly affects the development of discs composed of cells with wild type ept. CONCLUSIONS Together, these data show that loss of ept alters nuclear cell cycle control in developing imaginal discs and identify the DaPKC, presenilin, and rbf1 genes as modifiers of molecular and cellular phenotypes that result from loss of ept.
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Affiliation(s)
- M. Melissa Gilbert
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Brian S. Robinson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
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31
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Gilbert MM, Beam CK, Robinson BS, Moberg KH. Genetic interactions between the Drosophila tumor suppressor gene ept and the stat92E transcription factor. PLoS One 2009; 4:e7083. [PMID: 19787055 PMCID: PMC2747001 DOI: 10.1371/journal.pone.0007083] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 08/19/2009] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Tumor Susceptibility Gene-101 (TSG101) promotes the endocytic degradation of transmembrane proteins and is implicated as a mutational target in cancer, yet the effect of TSG101 loss on cell proliferation in vertebrates is uncertain. By contrast, Drosophila epithelial tissues lacking the TSG101 ortholog erupted (ept) develop as enlarged undifferentiated tumors, indicating that the gene can have anti-growth properties in a simple metazoan. A full understanding of pathways deregulated by loss of Drosophila ept will aid in understanding potential links between mammalian TSG101 and growth control. PRINCIPAL FINDINGS We have taken a genetic approach to the identification of pathways required for excess growth of Drosophila eye-antennal imaginal discs lacking ept. We find that this phenotype is very sensitive to the genetic dose of stat92E, the transcriptional effector of the Jak-Stat signaling pathway, and that this pathway undergoes strong activation in ept mutant cells. Genetic evidence indicates that stat92E contributes to cell cycle deregulation and excess cell size phenotypes that are observed among ept mutant cells. In addition, autonomous Stat92E hyper-activation is associated with altered tissue architecture in ept tumors and an effect on expression of the apical polarity determinant crumbs. CONCLUSIONS These findings identify ept as a cell-autonomous inhibitor of the Jak-Stat pathway and suggest that excess Jak-Stat signaling makes a significant contribution to proliferative and tissue architectural phenotypes that occur in ept mutant tissues.
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Affiliation(s)
- M. Melissa Gilbert
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Carolyn K. Beam
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Brian S. Robinson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Kenneth H. Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
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32
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Nicholson SC, Gilbert MM, Nicolay BN, Frolov MV, Moberg KH. The archipelago tumor suppressor gene limits rb/e2f-regulated apoptosis in developing Drosophila tissues. Curr Biol 2009; 19:1503-10. [PMID: 19733076 DOI: 10.1016/j.cub.2009.07.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 07/25/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The Drosophila archipelago gene (ago) encodes the specificity component of a ubiquitin ligase that targets the cyclin E and dMyc proteins for degradation. Its human ortholog, Fbw7, is commonly lost in cancers, suggesting that failure to degrade ago/Fbw7 targets drives excess tissue growth. RESULTS We find that ago loss induces hyperplasia of some organs but paradoxically reduces the size of the adult eye. This reflects a requirement for ago to restrict apoptotic activity of the rbf1/de2f1 pathway adjacent to the eye-specific morphogenetic furrow (MF): ago mutant cells display elevated de2f1 activity, express the prodeath dE2f1 targets hid and rpr, and undergo high rates of apoptosis. These phenotypes are dependent on rbf1, de2f1, hid, and the rbf1/de2f1 regulators cyclin E and dacapo but are independent of dp53. A transactivation-deficient de2f1 allele blocks MF-associated apoptosis of ago mutant cells but does not retard their clonal overgrowth, indicating that intact de2f1 function is required for the death but not overproliferation of ago cells. Epidermal growth factor receptor (EGFR) and wingless (wg) alleles also modify the ago apoptotic phenotype, indicating that these pathways may modulate the underlying sensitivity of ago mutant cells to apoptotic signals. CONCLUSIONS These data show that ago loss requires a collaborating block in cell death to efficiently drive tissue overgrowth and that this conditional phenotype reflects a role for ago in restricting apoptotic output of the rbf1/de2f1 pathway. Moreover, the susceptibility of ago mutant cells to succumb to this apoptotic program appears to depend on local variations in extracellular signaling that could thus determine tissue-specific fates of ago mutant cells.
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Affiliation(s)
- Sarah C Nicholson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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33
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Mortimer NT, Moberg KH. Regulation of Drosophila embryonic tracheogenesis by dVHL and hypoxia. Dev Biol 2009; 329:294-305. [PMID: 19285057 DOI: 10.1016/j.ydbio.2009.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 01/27/2009] [Accepted: 03/03/2009] [Indexed: 01/01/2023]
Abstract
The tracheal system of Drosophila melanogaster is an interconnected network of gas-filled epithelial tubes that develops during embryogenesis and functions as the main gas-exchange organ in the larva. Larval tracheal cells respond to hypoxia by activating a program of branching and growth driven by HIF-1alpha/sima-dependent expression of the breathless (btl) FGF receptor. By contrast, the ability of the developing embryonic tracheal system to respond to hypoxia and integrate hard-wired branching programs with sima-driven tracheal remodeling is not well understood. Here we show that embryonic tracheal cells utilize the conserved ubiquitin ligase dVHL to control the HIF-1 alpha/sima hypoxia response pathway, and identify two distinct phases of tracheal development with differing hypoxia sensitivities and outcomes: a relatively hypoxia-resistant 'early' phase during which sima activity conflicts with normal branching and stunts migration, and a relatively hypoxia-sensitive 'late' phase during which the tracheal system uses the dVHL/sima/btl pathway to drive increased branching and growth. Mutations in the archipelago (ago) gene, which antagonizes btl transcription, re-sensitize early embryos to hypoxia, indicating that their relative resistance can be reversed by elevating activity of the btl promoter. These findings reveal a second type of tracheal hypoxic response in which Sima activation conflicts with developmental tracheogenesis, and identify the dVHL and ago ubiquitin ligases as key determinants of hypoxia sensitivity in tracheal cells. The identification of an early stage of tracheal development that is vulnerable to hypoxia is an important addition to models of the invertebrate hypoxic response.
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Affiliation(s)
- Nathan T Mortimer
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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Mortimer NT, Moberg KH. The Drosophila F-box protein Archipelago controls levels of the Trachealess transcription factor in the embryonic tracheal system. Dev Biol 2007; 312:560-71. [PMID: 17976568 DOI: 10.1016/j.ydbio.2007.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 10/01/2007] [Accepted: 10/01/2007] [Indexed: 10/22/2022]
Abstract
The archipelago gene (ago) encodes the F-box specificity subunit of an SCF(skp-cullin-f box) ubiquitin ligase that inhibits cell proliferation in Drosophila melanogaster and suppresses tumorigenesis in mammals. ago limits mitotic activity by targeting cell cycle and cell growth proteins for ubiquitin-dependent degradation, but the diverse developmental roles of other F-box proteins suggests that it is likely to have additional protein targets. Here we show that ago is required for the post-mitotic shaping of the Drosophila embryonic tracheal system, and that it acts in this tissue by targeting the Trachealess (Trh) protein, a conserved bHLH-PAS transcription factor. ago restricts Trh levels in vivo and antagonizes transcription of the breathless FGF receptor, a known target of Trh in the tracheal system. At a molecular level, the Ago protein binds Trh and is required for proteasome-dependent elimination of Trh in response to expression of the Dysfusion protein. ago mutations that elevate Trh levels in vivo are defective in binding forms of Trh found in Dysfusion-positive cells. These data identify a novel function for the ago ubiquitin-ligase in tracheal morphogenesis via Trh and its target breathless, and suggest that ago has distinct functions in mitotic and post-mitotic cells that influence its role in development and disease.
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Affiliation(s)
- Nathan T Mortimer
- Department of Cell Biology, Emory University School of Medicine, 615 Michael St. WBRB 442, Atlanta, GA 30322, USA
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Abstract
A series of recently published studies have established that defects in endocytic sorting can elicit dramatic tissue overgrowth phenotypes in developing organs of the fruit fly Drosophila melanogaster. Such a link had been suggested by mammalian cell culture experiments almost ten years ago, but in vivo evidence of this link, and the mechanisms through which it might occur, had remained elusive. Drosophila has now proven to be an excellent developmental system in which to both document the effects of endocytic defects on tissue growth and patterning, and to probe the basis of these phenotypes. This work has begun to illuminate some surprising connections between the endocytic trafficking of protein cargoes and the control of cell proliferation and tissue architecture. These connections touch major cell biological processes, including cell division, growth, death, and polarity, and have begun to paint a complex, yet intriguing, picture of how defective endocytic sorting can affect developing tissues.
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Affiliation(s)
- M Melissa Gilbert
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Moberg KH, Schelble S, Burdick SK, Hariharan IK. Mutations in erupted, the Drosophila ortholog of mammalian tumor susceptibility gene 101, elicit non-cell-autonomous overgrowth. Dev Cell 2006; 9:699-710. [PMID: 16256744 DOI: 10.1016/j.devcel.2005.09.018] [Citation(s) in RCA: 246] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 09/08/2005] [Accepted: 09/29/2005] [Indexed: 01/13/2023]
Abstract
The reproducible pattern of organismal growth during metazoan development is the product of genetically controlled signaling pathways. Patterned activation of these pathways shapes developing organs and dictates overall organismal shape and size. Here, we show that patches of tissue that are mutant for the Drosophila Tsg101 ortholog, erupted, cause dramatic overproliferation of adjacent wild-type tissue. Tsg101 proteins function in endosomal sorting and are required to incorporate late endosomes into multivesicular bodies. Drosophila cells with impaired Tsg101 function show accumulation of the Notch receptor in intracellular compartments marked by the endosomal protein Hrs. This causes increased Notch-mediated signaling and ectopic expression of the Notch target gene unpaired (upd), which encodes the secreted ligand of the JAK-STAT pathway. Activation of JAK-STAT signaling in surrounding wild-type cells correlates with their overgrowth. These findings define a pathway by which changes in endocytic trafficking can regulate tissue growth in a non-cell-autonomous manner.
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Affiliation(s)
- Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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Kwak EL, Moberg KH, Wahrer DCR, Quinn JE, Gilmore PM, Graham CA, Hariharan IK, Harkin DP, Haber DA, Bell DW. Infrequent mutations of Archipelago (hAGO, hCDC4, Fbw7) in primary ovarian cancer. Gynecol Oncol 2005; 98:124-8. [PMID: 15913747 DOI: 10.1016/j.ygyno.2005.04.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 03/31/2005] [Accepted: 04/08/2005] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Archipelago (AGO, also known as hCdc4, Fbw7, or Sel-10) is an F-box containing component of the SCF complex implicated in the ubiquitination and proteolysis of cyclin E and c-Myc, and found to be mutated in 16% of endometrial carcinomas. We have previously reported somatic mutations in AGO in 3/10 ovarian cancer cell lines, but the frequency of such mutations in primary ovarian cancer is unknown. METHODS The coding sequence of AGO was analyzed in 95 primary sporadic ovarian tumors and 16 cases of familial ovarian cancer, and correlated with levels of cyclin E and c-Myc protein expression. Constructs encoding mutations in AGO were transfected into an AGO-null cell line to directly test their ability to regulate cyclin E and c-Myc levels. RESULTS Mutations were present in only 2 of 95 sporadic cases: a premature stop within the WD domain (471 Ter) and a missense change near the F-box (S245T). Both primary tumor specimens containing these mutations showed high levels of cyclin E and c-Myc, but reconstitution of an AGO-null cell line with constructs encoding these mutations showed 471 Ter to be inactive in regulating endogenous cyclin E and c-Myc levels, while the S245T mutant was indistinguishable from wild-type. No germ-line mutations were found in familial cases of ovarian cancer. CONCLUSION Somatic AGO mutations are infrequent in primary ovarian cancers and are unlikely to contribute to familial ovarian cancer. Reconstitution experiments, rather than measuring tumor levels of cyclin E and c-Myc, provide an effective approach to determine the functional significance of AGO mutations identified in human cancers.
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Affiliation(s)
- Eunice L Kwak
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, CNY-7, 13th Street, Charlestown, MA 02129, USA
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Moberg KH, Mukherjee A, Veraksa A, Artavanis-Tsakonas S, Hariharan IK. The Drosophila F Box Protein Archipelago Regulates dMyc Protein Levels In Vivo. Curr Biol 2004; 14:965-74. [PMID: 15182669 DOI: 10.1016/j.cub.2004.04.040] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Revised: 03/22/2004] [Accepted: 04/02/2004] [Indexed: 02/09/2023]
Abstract
BACKGROUND The Myc oncoprotein is an important regulator of cellular growth in metazoan organisms. Its levels and activity are tightly controlled in vivo by a variety of mechanisms. In normal cells, Myc protein is rapidly degraded, but the mechanism of its degradation is not well understood. RESULTS Here we present genetic and biochemical evidence that Archipelago (Ago), the F box component of an SCF-ubiquitin ligase and the Drosophila ortholog of a human tumor suppressor, negatively regulates the levels and activity of Drosophila Myc (dMyc) protein in vivo. Mutations in archipelago (ago) result in strongly elevated dMyc protein levels and increased tissue growth. Genetic interactions indicate that ago antagonizes dMyc function during development. Archipelago binds dMyc and regulates its stability, and the ability of Ago to bind dMyc in vitro correlates with its ability to inhibit dMyc accumulation in vivo. CONCLUSIONS Our data indicate that archipelago is an important inhibitor of dMyc in developing tissues. Because archipelago can also regulate Cyclin E levels and Notch activity, these results indicate how a single F box protein can be responsible for the degradation of key components of multiple pathways that control growth and cell cycle progression.
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Affiliation(s)
- Kenneth H Moberg
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129 USA.
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Abstract
In a recent study, Brennecke and colleagues show that bantam, a previously elusive Drosophila gene that promotes tissue growth, encodes a microRNA. The bantam microRNA regulates cell number in vivo and inhibits cell death by binding to the mRNA of the pro-apoptotic gene hid. These findings demonstrate that a single, tiny Drosophila RNA can regulate organ and organism size and link the nascent field of microRNA function to the study of pathways that coordinate cell death, cell growth and cell proliferation during the development of metazoan organisms.
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Affiliation(s)
- Kenneth H Moberg
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129, USA
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Abstract
The development of a complex multicellular organism requires a coordination of growth and cell division under the control of patterning mechanisms. Studies in yeast have pioneered our understanding of the relationship between growth and cell division. In recent years, many of the pathways that regulate growth in multicellular eukaryotes have been identified. This work has revealed interesting and unexpected relationships between mechanisms that regulate growth and the cell cycle machinery.
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Affiliation(s)
- N Tapon
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129, USA
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Moberg KH, Bell DW, Wahrer DC, Haber DA, Hariharan IK. Archipelago regulates Cyclin E levels in Drosophila and is mutated in human cancer cell lines. Nature 2001; 413:311-6. [PMID: 11565033 DOI: 10.1038/35095068] [Citation(s) in RCA: 360] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During Drosophila development and mammalian embryogenesis, exit from the cell cycle is contingent on tightly controlled downregulation of the activity of Cyclin E-Cdk2 complexes that normally promote the transition from G1 to S phase. Although protein degradation has a crucial role in downregulating levels of Cyclin E, many of the proteins that function in degradation of Cyclin E have not been identified. In a screen for Drosophila mutants that display increased cell proliferation, we identified archipelago, a gene encoding a protein with an F-box and seven tandem WD (tryptophan-aspartic acid) repeats. Here we show that archipelago mutant cells have persistently elevated levels of Cyclin E protein without increased levels of cyclin E RNA. They are under-represented in G1 fractions and continue to proliferate when their wild-type neighbours become quiescent. The Archipelago protein binds directly to Cyclin E and probably targets it for ubiquitin-mediated degradation. A highly conserved human homologue is present and is mutated in four cancer cell lines including three of ten derived from ovarian carcinomas. These findings implicate archipelago in developmentally regulated degradation of Cyclin E and potentially in the pathogenesis of human cancers.
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Affiliation(s)
- K H Moberg
- Massachusetts General Hospital Cancer Center, Charlestown, MA 02129, USA
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Carlberg AL, Moberg KH, Hall DJ. Tumor necrosis factor and gamma-interferon repress transcription from the c-myc P2 promoter by reducing E2F binding activity. Int J Oncol 1999; 15:121-6. [PMID: 10375604 DOI: 10.3892/ijo.15.1.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription of the c-myc gene in HeLa cells has been shown to be repressed by the combined action of tumor necrosis factor (TNF) and gamma-interferon (gamma-INF). Shown here, these two cytokines inhibit proliferation of Hela cells with a coordinate inhibition of c-myc gene expression. It was found that these two cytokines exert their effects on the more proximal region of the c-myc P2 promoter. Using c-myc promoter:CAT constructs, it was found that the combined action of these cytokines significantly repress transcription from P2. This repression occurred through the E2F site within the promoter and not the ME1a2 or ME1a1 sites. However, these cytokines had no effect on transcription from the rous sarcoma virus promoter or the SV40 virus early promoter. Protein binding assays indicate that TNF and gamma-INF did not effect the ability of the ME1a2 factor to bind to its site but did significantly repress E2F factor binding to its DNA sequence.
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Affiliation(s)
- A L Carlberg
- Department of Orthopedic Surgery, 510 Curtis, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Logan TJ, Moberg KH, Hall DJ. Multiprotein complex formation on the c-myc promoter. Biochem Mol Biol Int 1997; 43:945-53. [PMID: 9415803 DOI: 10.1080/15216549700204761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The E2F element is a cis-acting DNA sequence within the P2 promoter of c-myc proto-oncogene. While it is required for optimal transcription, the multiprotein complexes formed on this site have not been well characterized. We show that in extracts of human glioblastoma cells and NIH3T3 fibroblasts, significant E2F transcription factor binding to the c-myc E2F site occurs as a both a monomer (the active form) and as only two mutually exclusive complexes with the retinoblastoma gene product (pRb) or the cyclin A protein. The E2F protein monomer was found predominantly in the cytosolic fraction of the cellular extracts while the pRb and cyclin A complexes in the nuclear fraction, indicating that the monomer has novel physical properties. Thus, protein complex formation on the c-myc E2F site appears to contribute in a unique way to transcriptional activation.
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Affiliation(s)
- T J Logan
- Dept of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Zhu L, Enders GH, Wu CL, Starz MA, Moberg KH, Lees JA, Dyson N, Harlow E. Growth suppression by members of the retinoblastoma protein family. Cold Spring Harb Symp Quant Biol 1994; 59:75-84. [PMID: 7587134 DOI: 10.1101/sqb.1994.059.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- L Zhu
- Massachusetts General Hospital Cancer Center, Charlestown 02129, USA
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Abstract
Here we analyzed the effect of the suppressor proto-oncogene p53 on transcription from the P2 promoter of the murine c-myc gene. c-myc promoter constructs were coupled to the chloramphenicol acetyl-transferase (CAT) gene and were transiently transfected into a human glial cell along with plasmids overexpressing wild-type or mutant p53. It was found that significant repression of c-myc transcription took place following cotransfection with wild-type but not mutant p53. However wild-type p53 did not suppress transcription from the SV40 early promoter or from the MHC promoter. Promoter-CAT constructs containing only the ME1a2 or E2F elements, from the P2 promoter, were repressed by p53, indicating that p53 may exert its effect at these two sites within the P2 promoter. Finally, when the SV40 T antigen and wild-type p53 were expressed together in glial cells the repressive effect of p53 was abolished.
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Affiliation(s)
- K H Moberg
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Abstract
The ME1a1 and ME1a2 elements are cis-acting DNA sequences that exist at positions -46 and -85, respectively, within the P2 promoter of the c-myc gene. These elements are required for optimal transcription initiation from P2. The proteins that bind to these elements are identical or very similar. Here we have isolated a cDNA clone that encodes the carboxy-terminal 494 amino acids of the human ME1a1/ME1a2 factor. This factor is referred to as "ZF87" (zinc-finger protein, 87 kilodaltons). ZF87 specifically binds the ME1a1 element with higher affinity than the ME1a2 element. Western blot analysis indicates that the full-length protein has a relative molecular mass of approximately 87,000 daltons, and Northern blot analysis shows that it is encoded by a 5-kb transcript. ZF87 contains six zinc-finger domains, of the Cys2-His2 type, at the carboxy terminus of the protein. The protein also contains extended tracts of polyalanine.
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Affiliation(s)
- J J Pyrc
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Moberg KH, Logan TJ, Tyndall WA, Hall DJ. Three distinct elements within the murine c-myc promoter are required for transcription. Oncogene 1992; 7:411-21. [PMID: 1549358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have undertaken a detailed analysis of the cis-acting elements that are required for optimal transcription initiation from P2, the major promoter of the murine c-myc gene. We find that three elements contribute to promoter strength, termed ME1a2, E2F and ME1a1 at positions -85, -64 and -46 respectively (relative to P2). Individually the elements are weak, but combined they contribute to full promoter activity, all acting in a positive fashion. The E2F element is the site at which the SV40 large T antigen transactivates the c-myc promoter. However, transactivation requires the presence of the ME1a2 or ME1a1 elements in addition to E2F. By a number of criteria it appears that the ME1a2 and ME1a1 elements bind the same or a very closely related protein (monomer Mr 94,000). It was found that Hela cells contain a novel factor that is capable of binding to the ME1a1 and ME1a2 elements but only in the presence of the protein-dissociating agents deoxycholate or formamide. Finally, the E2F factor binds DNA both as a monomer and as a multiprotein complex; the latter is cell type specific. Both types of bound E2F factor form less stable protein-DNA complexes than the ME1a2/ME1a1 factor.
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Affiliation(s)
- K H Moberg
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Abstract
The cis-acting elements governing transcription from the murine c-myc P2 promoter have not been well defined. To gain a better understanding of the nature of the protein-DNA interactions that take place on the P2 promoter, protein binding assays were performed. The ME1a2 and E2F factors appear to be the predominant proteins bound to a region spanning positions -140 to -24 relative to the P2 transcription start site. By a number of criteria, these factors appear to be distinct. When c-myc promoter sequences were coupled to the chloramphenicol acetyltransferase gene (CAT) and transiently transfected into tissue culture cells it was found that optimal transcription from P2 was heavily dependent on the ME1a2 element.
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Affiliation(s)
- K H Moberg
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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