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Moriya A, Otsuka K, Naoi R, Terahata M, Takeda K, Kondo S, Adachi-Yamada T. Creation of Knock-In Alleles of Insulin Receptor Tagged by Fluorescent Proteins mCherry or EYFP in Fruit Fly Drosophila melanogaster. Zoolog Sci 2024; 41:230-243. [PMID: 38587918 DOI: 10.2108/zs230075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 12/19/2023] [Indexed: 04/10/2024]
Abstract
The insulin/insulin-like growth factor-like signaling (IIS) pathway is highly conserved across metazoans and regulates numerous physiological functions, including development, metabolism, fecundity, and lifespan. The insulin receptor (InR), a crucial membrane receptor in the IIS pathway, is known to be ubiquitously expressed in various tissues, albeit at generally low levels, and its subcellular localization remains incompletely characterized. In this study, we employed CRISPR-mediated mutagenesis in the fruit fly Drosophila to create knock-in alleles of InR tagged with fluorescent proteins (InR::mCherry or InR::EYFP). By inserting the coding sequence of the fluorescent proteins mCherry or EYFP near the end of the coding sequence of the endogenous InR gene, we could trace the natural InR protein through their fluorescence. As an example, we investigated epithelial cells of the male accessory gland (AG), an internal reproductive organ, and identified two distinct patterns of InR::mCherry localization. In young AG, InR::mCherry accumulated on the basal plasma membrane between cells, whereas in mature AG, it exhibited intracellular localization as multiple puncta, indicating endocytic recycling of InR during cell growth. In the AG senescence accelerated by the mutation of Diuretic hormone 31 (Dh31), the presence of InR::mCherry puncta was more pronounced compared to the wild type. These findings raise expectations for the utility of the newly created InR::mCherry/EYFP alleles for studying the precise expression levels and subcellular localization of InR. Furthermore, this fluorescently tagged allele approach can be extended to investigate other membrane receptors with low abundance, facilitating the direct examination of their true expression and localization.
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Affiliation(s)
- Ayano Moriya
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Kei Otsuka
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
- Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Riku Naoi
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Mayu Terahata
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Koji Takeda
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
- Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Shu Kondo
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Katsushika-ku, Tokyo 125-8585, Japan
| | - Takashi Adachi-Yamada
- Graduate Course in Life Science, Graduate School of Science, Gakushuin University, Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan,
- Department of Life Science, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
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2
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Hu Y, Comjean A, Attrill H, Antonazzo G, Thurmond J, Chen W, Li F, Chao T, Mohr SE, Brown NH, Perrimon N. PANGEA: a new gene set enrichment tool for Drosophila and common research organisms. Nucleic Acids Res 2023; 51:W419-W426. [PMID: 37125646 PMCID: PMC10320058 DOI: 10.1093/nar/gkad331] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/28/2023] [Accepted: 04/29/2023] [Indexed: 05/02/2023] Open
Abstract
Gene set enrichment analysis (GSEA) plays an important role in large-scale data analysis, helping scientists discover the underlying biological patterns over-represented in a gene list resulting from, for example, an 'omics' study. Gene Ontology (GO) annotation is the most frequently used classification mechanism for gene set definition. Here we present a new GSEA tool, PANGEA (PAthway, Network and Gene-set Enrichment Analysis; https://www.flyrnai.org/tools/pangea/), developed to allow a more flexible and configurable approach to data analysis using a variety of classification sets. PANGEA allows GO analysis to be performed on different sets of GO annotations, for example excluding high-throughput studies. Beyond GO, gene sets for pathway annotation and protein complex data from various resources as well as expression and disease annotation from the Alliance of Genome Resources (Alliance). In addition, visualizations of results are enhanced by providing an option to view network of gene set to gene relationships. The tool also allows comparison of multiple input gene lists and accompanying visualisation tools for quick and easy comparison. This new tool will facilitate GSEA for Drosophila and other major model organisms based on high-quality annotated information available for these species.
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Affiliation(s)
- Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Aram Comjean
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Helen Attrill
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Giulia Antonazzo
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Jim Thurmond
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Weihang Chen
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Fangge Li
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Tiffany Chao
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Stephanie E Mohr
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Nicholas H Brown
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Boston, MA 02138, USA
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3
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Hu Y, Comjean A, Attrill H, Antonazzo G, Thurmond J, Li F, Chao T, Mohr SE, Brown NH, Perrimon N. PANGEA: A New Gene Set Enrichment Tool for Drosophila and Common Research Organisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.20.529262. [PMID: 36865134 PMCID: PMC9980003 DOI: 10.1101/2023.02.20.529262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Gene set enrichment analysis (GSEA) plays an important role in large-scale data analysis, helping scientists discover the underlying biological patterns over-represented in a gene list resulting from, for example, an 'omics' study. Gene Ontology (GO) annotation is the most frequently used classification mechanism for gene set definition. Here we present a new GSEA tool, PANGEA (PAthway, Network and Gene-set Enrichment Analysis; https://www.flyrnai.org/tools/pangea/ ), developed to allow a more flexible and configurable approach to data analysis using a variety of classification sets. PANGEA allows GO analysis to be performed on different sets of GO annotations, for example excluding high-throughput studies. Beyond GO, gene sets for pathway annotation and protein complex data from various resources as well as expression and disease annotation from the Alliance of Genome Resources (Alliance). In addition, visualisations of results are enhanced by providing an option to view network of gene set to gene relationships. The tool also allows comparison of multiple input gene lists and accompanying visualisation tools for quick and easy comparison. This new tool will facilitate GSEA for Drosophila and other major model organisms based on high-quality annotated information available for these species.
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Affiliation(s)
- Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Aram Comjean
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Helen Attrill
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Giulia Antonazzo
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Jim Thurmond
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Fangge Li
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Tiffany Chao
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Stephanie E. Mohr
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Nicholas H. Brown
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Boston, MA 02138, USA
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4
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A genetic strategy to measure insulin signaling regulation and physiology in Drosophila. PLoS Genet 2023; 19:e1010619. [PMID: 36730473 PMCID: PMC9928101 DOI: 10.1371/journal.pgen.1010619] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 02/14/2023] [Accepted: 01/15/2023] [Indexed: 02/04/2023] Open
Abstract
Insulin regulation is a hallmark of health, and impaired insulin signaling promotes metabolic diseases like diabetes mellitus. However, current assays for measuring insulin signaling in all animals remain semi-quantitative and lack the sensitivity, tissue-specificity or temporal resolution needed to quantify in vivo physiological signaling dynamics. Insulin signal transduction is remarkably conserved across metazoans, including insulin-dependent phosphorylation and regulation of Akt/Protein kinase B. Here, we generated transgenic fruit flies permitting tissue-specific expression of an immunoepitope-labelled Akt (AktHF). We developed enzyme-linked immunosorption assays (ELISA) to quantify picomolar levels of phosphorylated (pAktHF) and total AktHF in single flies, revealing dynamic tissue-specific physiological regulation of pAktHF in response to fasting and re-feeding, exogenous insulin, or targeted genetic suppression of established insulin signaling regulators. Genetic screening revealed Pp1-87B as an unrecognized regulator of Akt and insulin signaling. Tools and concepts here provide opportunities to discover tissue-specific regulators of in vivo insulin signaling responses.
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5
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Hocaoglu H, Wang L, Yang M, Yue S, Sieber M. Heritable shifts in redox metabolites during mitochondrial quiescence reprogramme progeny metabolism. Nat Metab 2021; 3:1259-1274. [PMID: 34545253 PMCID: PMC8462065 DOI: 10.1038/s42255-021-00450-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 08/06/2021] [Indexed: 02/08/2023]
Abstract
Changes in maternal diet and metabolic defects in mothers can profoundly affect health and disease in their progeny. However, the biochemical mechanisms that induce the initial reprogramming events at the cellular level have remained largely unknown owing to limitations in obtaining pure populations of quiescent oocytes. Here, we show that the precocious onset of mitochondrial respiratory quiescence causes a reprogramming of progeny metabolic state. The premature onset of mitochondrial respiratory quiescence drives the lowering of Drosophila oocyte NAD+ levels. NAD+ depletion in the oocyte leads to reduced methionine cycle production of the methyl donor S-adenosylmethionine in embryos and lower levels of histone H3 lysine 27 trimethylation, resulting in enhanced intestinal lipid metabolism in progeny. In addition, we show that triggering cellular quiescence in mammalian cells and chemotherapy-resistant human cancer cell models induces cellular reprogramming events identical to those seen in Drosophila, suggesting a conserved metabolic mechanism in systems reliant on quiescent cells.
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Affiliation(s)
- Helin Hocaoglu
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Lei Wang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Mengye Yang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sibiao Yue
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Matthew Sieber
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX, USA.
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6
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Kim SK, Tsao DD, Suh GSB, Miguel-Aliaga I. Discovering signaling mechanisms governing metabolism and metabolic diseases with Drosophila. Cell Metab 2021; 33:1279-1292. [PMID: 34139200 PMCID: PMC8612010 DOI: 10.1016/j.cmet.2021.05.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/30/2021] [Accepted: 05/25/2021] [Indexed: 12/18/2022]
Abstract
There has been rapid growth in the use of Drosophila and other invertebrate systems to dissect mechanisms governing metabolism. New assays and approaches to physiology have aligned with superlative genetic tools in fruit flies to provide a powerful platform for posing new questions, or dissecting classical problems in metabolism and disease genetics. In multiple examples, these discoveries exploit experimental advantages as-yet unavailable in mammalian systems. Here, we illustrate how fly studies have addressed long-standing questions in three broad areas-inter-organ signaling through hormonal or neural mechanisms governing metabolism, intestinal interoception and feeding, and the cellular and signaling basis of sexually dimorphic metabolism and physiology-and how these findings relate to human (patho)physiology. The imaginative application of integrative physiology and related approaches in flies to questions in metabolism is expanding, and will be an engine of discovery, revealing paradigmatic features of metabolism underlying human diseases and physiological equipoise in health.
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Affiliation(s)
- Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine (Endocrinology), Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Deborah D Tsao
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Greg S B Suh
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea.
| | - Irene Miguel-Aliaga
- MRC London Institute of Medical Sciences, London, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK.
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7
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Kim MJ, O'Connor MB. Drosophila Activin signaling promotes muscle growth through InR/TORC1-dependent and -independent processes. Development 2021; 148:dev190868. [PMID: 33234715 PMCID: PMC7823159 DOI: 10.1242/dev.190868] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 11/16/2020] [Indexed: 12/25/2022]
Abstract
The Myostatin/Activin branch of the TGF-β superfamily acts as a negative regulator of vertebrate skeletal muscle size, in part, through downregulation of insulin/insulin-like growth factor 1 (IGF-1) signaling. Surprisingly, recent studies in Drosophila indicate that motoneuron-derived Activin signaling acts as a positive regulator of muscle size. Here we demonstrate that Drosophila Activin signaling promotes the growth of muscle cells along all three axes: width, thickness and length. Activin signaling positively regulates the insulin receptor (InR)/TORC1 pathway and the level of Myosin heavy chain (Mhc), an essential sarcomeric protein, via increased Pdk1 and Akt1 expression. Enhancing InR/TORC1 signaling in the muscle of Activin pathway mutants restores Mhc levels close to those of the wild type, but only increases muscle width. In contrast, hyperactivation of the Activin pathway in muscles increases overall larval body and muscle fiber length, even when Mhc levels are lowered by suppression of TORC1. Together, these results indicate that the Drosophila Activin pathway regulates larval muscle geometry and body size via promoting InR/TORC1-dependent Mhc production and the differential assembly of sarcomeric components into either pre-existing or new sarcomeric units depending on the balance of InR/TORC1 and Activin signals.
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Affiliation(s)
- Myung-Jun Kim
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael B O'Connor
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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8
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Parniewska MM, Stocker H. The Splicing Factor SF2 Is Critical for Hyperproliferation and Survival in a TORC1-Dependent Model of Early Tumorigenesis in Drosophila. Int J Mol Sci 2020; 21:ijms21124465. [PMID: 32599686 PMCID: PMC7352841 DOI: 10.3390/ijms21124465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 01/05/2023] Open
Abstract
The Target of Rapamycin complex 1 (TORC1) is an evolutionarily conserved kinase complex coordinating cellular growth with nutritional conditions and growth factor signaling, and its activity is elevated in many cancer types. The use of TORC1 inhibitors as anticancer drugs is, however, limited by unwanted side-effects and development of resistance. We therefore attempted to identify limiting modulators or downstream effectors of TORC1 that could serve as therapeutic targets. Drosophila epithelial tissues that lack the tumor suppressor Pten hyperproliferate upon nutrient restriction in a TORC1-dependent manner. We probed candidates of the TORC1 signaling network for factors limiting the overgrowth of Pten mutant tissues. The serine/arginine-rich splicing factor 2 (SF2) was identified as the most limiting factor: SF2 knockdown drives Pten mutant cells into apoptosis, while not affecting control tissue. SF2 acts downstream of or in parallel to TORC1 but is not required for the activation of the TORC1 target S6K. Transcriptomics analysis revealed transcripts with alternatively used exons regulated by SF2 in the tumor context, including p53. SF2 may therefore represent a highly specific therapeutic target for tumors with hyperactive TORC1 signaling.
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9
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Toprak U, Hegedus D, Doğan C, Güney G. A journey into the world of insect lipid metabolism. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 104:e21682. [PMID: 32335968 DOI: 10.1002/arch.21682] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/08/2020] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
Lipid metabolism is fundamental to life. In insects, it is critical, during reproduction, flight, starvation, and diapause. The coordination center for insect lipid metabolism is the fat body, which is analogous to the vertebrate adipose tissue and liver. Fat body contains various different cell types; however, adipocytes and oenocytes are the primary cells related to lipid metabolism. Lipid metabolism starts with the hydrolysis of dietary lipids, absorption of lipid monomers, followed by lipid transport from midgut to the fat body, lipogenesis or lipolysis in the fat body, and lipid transport from fat body to other sites demanding energy. Lipid metabolism is under the control of hormones, transcription factors, secondary messengers and posttranscriptional modifications. Primarily, lipogenesis is under the control of insulin-like peptides that activate lipogenic transcription factors, such as sterol regulatory element-binding proteins, whereas lipolysis is coordinated by the adipokinetic hormone that activates lipolytic transcription factors, such as forkhead box class O and cAMP-response element-binding protein. Calcium is the primary-secondary messenger affecting lipid metabolism and has different outcomes depending on the site of lipogenesis or lipolysis. Phosphorylation is central to lipid metabolism and multiple phosphorylases are involved in lipid accumulation or hydrolysis. Although most of the knowledge of insect lipid metabolism comes from the studies on the model Drosophila; other insects, in particular those with obligatory or facultative diapause, also have great potential to study lipid metabolism. The use of these models would significantly improve our knowledge of insect lipid metabolism.
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Affiliation(s)
- Umut Toprak
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | - Dwayne Hegedus
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Cansu Doğan
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | - Gözde Güney
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
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10
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Borreguero-Muñoz N, Fletcher GC, Aguilar-Aragon M, Elbediwy A, Vincent-Mistiaen ZI, Thompson BJ. The Hippo pathway integrates PI3K-Akt signals with mechanical and polarity cues to control tissue growth. PLoS Biol 2019; 17:e3000509. [PMID: 31613895 PMCID: PMC6814241 DOI: 10.1371/journal.pbio.3000509] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 10/25/2019] [Accepted: 10/03/2019] [Indexed: 11/19/2022] Open
Abstract
The Hippo signalling pathway restricts cell proliferation in animal tissues by inhibiting Yes-associated protein (YAP or YAP1) and Transcriptional Activator with a PDZ domain (TAZ or WW-domain-containing transcriptional activator [WWTR1]), coactivators of the Scalloped (Sd or TEAD) DNA-binding transcription factor. Drosophila has a single YAP/TAZ homolog named Yorkie (Yki) that is regulated by Hippo pathway signalling in response to epithelial polarity and tissue mechanics during development. Here, we show that Yki translocates to the nucleus to drive Sd-mediated cell proliferation in the ovarian follicle cell epithelium in response to mechanical stretching caused by the growth of the germline. Importantly, mechanically induced Yki nuclear localisation also requires nutritionally induced insulin/insulin-like growth factor 1 (IGF-1) signalling (IIS) via phosphatidyl inositol-3-kinase (PI3K), phosphoinositide-dependent kinase 1 (PDK1 or PDPK1), and protein kinase B (Akt or PKB) in the follicular epithelium. We find similar results in the developing Drosophila wing, where Yki becomes nuclear in the mechanically stretched cells of the wing pouch during larval feeding, which induces IIS, but translocates to the cytoplasm upon cessation of feeding in the third instar stage. Inactivating Akt prevents nuclear Yki localisation in the wing disc, while ectopic activation of the insulin receptor, PI3K, or Akt/PKB is sufficient to maintain nuclear Yki in mechanically stimulated cells of the wing pouch even after feeding ceases. Finally, IIS also promotes YAP nuclear localisation in response to mechanical cues in mammalian skin epithelia. Thus, the Hippo pathway has a physiological function as an integrator of epithelial cell polarity, tissue mechanics, and nutritional cues to control cell proliferation and tissue growth in both Drosophila and mammals.
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Affiliation(s)
| | - Georgina C. Fletcher
- Epithelial Biology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Mario Aguilar-Aragon
- Epithelial Biology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Ahmed Elbediwy
- Epithelial Biology Laboratory, The Francis Crick Institute, London, United Kingdom
| | | | - Barry J. Thompson
- Epithelial Biology Laboratory, The Francis Crick Institute, London, United Kingdom
- EMBL Australia, Department of Cancer Biology & Therapeutics, The John Curtin School of Medical Research, The Australian National University, Acton, Australia
- * E-mail:
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11
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Suzawa M, Muhammad NM, Joseph BS, Bland ML. The Toll Signaling Pathway Targets the Insulin-like Peptide Dilp6 to Inhibit Growth in Drosophila. Cell Rep 2019; 28:1439-1446.e5. [DOI: 10.1016/j.celrep.2019.07.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/28/2019] [Accepted: 07/03/2019] [Indexed: 01/08/2023] Open
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12
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The Effect of Inulin on Lifespan, Related Gene Expression and Gut Microbiota in InRp5545/TM3 Mutant Drosophila melanogaster: A Preliminary Study. Nutrients 2019; 11:nu11030636. [PMID: 30875994 PMCID: PMC6470987 DOI: 10.3390/nu11030636] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/07/2019] [Accepted: 03/11/2019] [Indexed: 12/16/2022] Open
Abstract
Inulin is considered an efficient prebiotic and is beneficial for metabolic diseases via promoting intestinal probiotic enrichment and the metabolites of short-chain fatty acids (SCFAs). However, the effect of inulin on patients with InR deficiencies has seldom been reported. In this study, the lifespan, related gene expression, and gut microbiota of InRp5545/TM3 (insulin receptor mutant) Drosophila melanogaster under inulin treatment were investigated. The results showed that the lifespan was extended in only males and not in females. Furthermore, distinctly different patterns of gene expression were found between males and females, especially in the insulin/insulin-like growth factor (IGF)-like signalling (IIS) and target of rapamycin (TOR) pathways. Additionally, as a link between inulin and lifespan responses, the gut microbiota was distinctly separated by gender in both the standard diet group and the inulin treatment group, and the relationship between lifespan and the gut microbiota community was stronger in male flies than in females. This study provides preliminary evidence for the gender-dependent lifespan responses to inulin in insulin signalling-deficient Drosophila. However, controls such as wild-type and TM3 flies, and more InR mutant strains with different genetic backgrounds need to be further investigated to elucidate the mechanisms underlying the phenomenon.
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13
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Kim AR, Choi KW. TRiC/CCT chaperonins are essential for organ growth by interacting with insulin/TOR signaling in Drosophila. Oncogene 2019; 38:4739-4754. [PMID: 30792539 PMCID: PMC6756063 DOI: 10.1038/s41388-019-0754-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 12/28/2018] [Accepted: 02/08/2019] [Indexed: 12/12/2022]
Abstract
Organ size is regulated by intercellular signaling for cell growth and proliferation. The TOR pathway mediates a key signaling mechanism for controlling cell size and number in organ growth. Chaperonin containing TCP-1 (CCT) is a complex that assists protein folding and function, but its role in animal development is largely unknown. Here we show that the CCT complex is required for organ growth by interacting with the TOR pathway in Drosophila. Reduction of CCT4 results in growth defects by affecting both cell size and proliferation. Loss of CCT4 causes preferential cell death anterior to the morphogenetic furrow in the eye disc and within wing pouch in the wing disc. Depletion of any CCT subunit in the eye disc results in headless phenotype. Overgrowth by active TOR signaling is suppressed by CCT RNAi. The CCT complex physically interacts with TOR signaling components including TOR, Rheb, and S6K. Loss of CCT leads to decreased phosphorylation of S6K and S6 while increasing phosphorylation of Akt. Insulin/TOR signaling is also necessary and sufficient for promoting CCT complex transcription. Our data provide evidence that the CCT complex regulates organ growth by directly interacting with the TOR signaling pathway.
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Affiliation(s)
- Ah-Ram Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, Republic of Korea.,Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Kwang-Wook Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, Republic of Korea.
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14
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Hu Y, Sopko R, Chung V, Foos M, Studer RA, Landry SD, Liu D, Rabinow L, Gnad F, Beltrao P, Perrimon N. iProteinDB: An Integrative Database of Drosophila Post-translational Modifications. G3 (BETHESDA, MD.) 2019; 9:1-11. [PMID: 30397019 PMCID: PMC6325894 DOI: 10.1534/g3.118.200637] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/02/2018] [Indexed: 02/08/2023]
Abstract
Post-translational modification (PTM) serves as a regulatory mechanism for protein function, influencing their stability, interactions, activity and localization, and is critical in many signaling pathways. The best characterized PTM is phosphorylation, whereby a phosphate is added to an acceptor residue, most commonly serine, threonine and tyrosine in metazoans. As proteins are often phosphorylated at multiple sites, identifying those sites that are important for function is a challenging problem. Considering that any given phosphorylation site might be non-functional, prioritizing evolutionarily conserved phosphosites provides a general strategy to identify the putative functional sites. To facilitate the identification of conserved phosphosites, we generated a large-scale phosphoproteomics dataset from Drosophila embryos collected from six closely-related species. We built iProteinDB (https://www.flyrnai.org/tools/iproteindb/), a resource integrating these data with other high-throughput PTM datasets, including vertebrates, and manually curated information for Drosophila At iProteinDB, scientists can view the PTM landscape for any Drosophila protein and identify predicted functional phosphosites based on a comparative analysis of data from closely-related Drosophila species. Further, iProteinDB enables comparison of PTM data from Drosophila to that of orthologous proteins from other model organisms, including human, mouse, rat, Xenopus tropicalis, Danio rerio, and Caenorhabditis elegans.
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Affiliation(s)
- Yanhui Hu
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Richelle Sopko
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Verena Chung
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Marianna Foos
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Romain A Studer
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Sean D Landry
- Department of Bioinformatics, Cell Signaling Technology Inc., 3 Trask Lane, Danvers, MA 01923
| | - Daniel Liu
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Leonard Rabinow
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Florian Gnad
- Department of Bioinformatics, Cell Signaling Technology Inc., 3 Trask Lane, Danvers, MA 01923
| | - Pedro Beltrao
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
- Drosophila RNAi Screening Center, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115
- Howard Hughes Medical Institute, 77 Avenue Louis Pasteur, Boston, MA 02115
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15
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Xue B, Li FC, Tian JH, Li JX, Cheng XY, Hu JH, Hu JS, Li B. Titanium nanoparticles influence the Akt/Tor signal pathway in the silkworm, Bombyx mori, silk gland. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2018; 99:e21470. [PMID: 29709078 DOI: 10.1002/arch.21470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Various nanoparticles, such as silver nanoparticles (AgNPs) and titanium nanoparticles (TiO2 NPs) are increasingly used in industrial processes. Because they are released into the environment, research into their influence on the biosphere is necessary. Among its other effects, dietary TiO2 NPs promotes silk protein synthesis in silkworms, which prompted our hypothesis that TiO2 NPs influence protein kinase B (Akt)/Target of rapamycin (Tor) signaling pathway (Akt/Tor) signaling in their silk glands. The Akt/Tor signaling pathway is a principle connector integrating cellular reactions to growth factors, metabolites, nutrients, protein synthesis, and stress. We tested our hypothesis by determining the influence of dietary TiO2 NPs (for 72 h) and, separately, of two Akt/Tor pathway inhibitors (LY294002 and rapamycin) on expression of Akt/Tor signaling pathway genes and proteins in the silk glands. TiO2 NPs treatments led to increased accumulation of mRNAs for Akt, Tor1 and Tor2 by 1.6-, 12.1-, and 4.8-fold. Dietary inhibitors led to 2.6- to 4-fold increases in mRNAs encoding Akt and substantial decreases in mRNAs encoding Tor1 and Tor2. Western blot analysis showed that dietary TiO2 NPs increased the phosphorylation of Akt and its downstream proteins. LY294002 treatments led to inhibition of Akt phosphorylation and its downstream proteins and rapamycin treatments similarly inhibited the phosphorylation of Tor-linked downstream proteins. These findings support our hypothesis that TiO2 NPs influence Akt/Tor signaling in silk glands. The significance of this work is identification of specific sites of TiO2 NPs actions.
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Affiliation(s)
- Bin Xue
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Fan-Chi Li
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Jiang-Hai Tian
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Jin-Xin Li
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Xiao-Yu Cheng
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Jia-Huan Hu
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Jing-Sheng Hu
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
| | - Bing Li
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, P.R. China
- National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, P.R. China
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16
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Regulation of Carbohydrate Energy Metabolism in Drosophila melanogaster. Genetics 2018; 207:1231-1253. [PMID: 29203701 DOI: 10.1534/genetics.117.199885] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 07/02/2017] [Indexed: 02/08/2023] Open
Abstract
Carbohydrate metabolism is essential for cellular energy balance as well as for the biosynthesis of new cellular building blocks. As animal nutrient intake displays temporal fluctuations and each cell type within the animal possesses specific metabolic needs, elaborate regulatory systems are needed to coordinate carbohydrate metabolism in time and space. Carbohydrate metabolism is regulated locally through gene regulatory networks and signaling pathways, which receive inputs from nutrient sensors as well as other pathways, such as developmental signals. Superimposed on cell-intrinsic control, hormonal signaling mediates intertissue information to maintain organismal homeostasis. Misregulation of carbohydrate metabolism is causative for many human diseases, such as diabetes and cancer. Recent work in Drosophila melanogaster has uncovered new regulators of carbohydrate metabolism and introduced novel physiological roles for previously known pathways. Moreover, genetically tractable Drosophila models to study carbohydrate metabolism-related human diseases have provided new insight into the mechanisms of pathogenesis. Due to the high degree of conservation of relevant regulatory pathways, as well as vast possibilities for the analysis of gene-nutrient interactions and tissue-specific gene function, Drosophila is emerging as an important model system for research on carbohydrate metabolism.
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17
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Nowak K, Gupta A, Stocker H. FoxO restricts growth and differentiation of cells with elevated TORC1 activity under nutrient restriction. PLoS Genet 2018; 14:e1007347. [PMID: 29677182 PMCID: PMC5931687 DOI: 10.1371/journal.pgen.1007347] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/02/2018] [Accepted: 03/30/2018] [Indexed: 11/19/2022] Open
Abstract
TORC1, a central regulator of cell survival, growth, and metabolism, is activated in a variety of cancers. Loss of the tumor suppressors PTEN and Tsc1/2 results in hyperactivation of TORC1. Tumors caused by the loss of PTEN, but not Tsc1/2, are often malignant and have been shown to be insensitive to nutrient restriction (NR). In Drosophila, loss of PTEN or Tsc1 results in hypertrophic overgrowth of epithelial tissues under normal nutritional conditions, and an enhanced TORC1-dependent hyperplastic overgrowth of PTEN mutant tissue under NR. Here we demonstrate that epithelial cells lacking Tsc1 or Tsc2 also acquire a growth advantage under NR. The overgrowth correlates with high TORC1 activity, and activating TORC1 downstream of Tsc1 by overexpression of Rheb is sufficient to enhance tissue growth. In contrast to cells lacking PTEN, Tsc1 mutant cells show decreased PKB activity, and the extent of Tsc1 mutant overgrowth is dependent on the loss of PKB-mediated inhibition of the transcription factor FoxO. Removal of FoxO function from Tsc1 mutant tissue induces massive hyperplasia, precocious differentiation, and morphological defects specifically under NR, demonstrating that FoxO activation is responsible for restricting overgrowth of Tsc1 mutant tissue. The activation status of FoxO may thus explain why tumors caused by the loss of Tsc1-in contrast to PTEN-rarely become malignant.
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Affiliation(s)
- Katarzyna Nowak
- Institute of Molecular Systems Biology, ETH Zürich, Auguste-Piccard-Hof 1, Zürich, Switzerland
| | - Avantika Gupta
- Institute of Molecular Systems Biology, ETH Zürich, Auguste-Piccard-Hof 1, Zürich, Switzerland
| | - Hugo Stocker
- Institute of Molecular Systems Biology, ETH Zürich, Auguste-Piccard-Hof 1, Zürich, Switzerland
- * E-mail:
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18
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Fischer Z, Das R, Shipman A, Fan JY, Pence L, Bouyain S, Dobens LL. A Drosophila model of insulin resistance associated with the human TRIB3 Q/R polymorphism. Dis Model Mech 2017; 10:1453-1464. [PMID: 29025897 PMCID: PMC5769606 DOI: 10.1242/dmm.030619] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 10/05/2017] [Indexed: 12/12/2022] Open
Abstract
Members of the Tribbles family of proteins are conserved pseudokinases with diverse roles in cell growth and proliferation. Both Drosophila Tribbles (Trbl) and vertebrate Trib3 proteins bind to the kinase Akt (Akt1) to block its phosphorylation activation and reduce downstream insulin-stimulated anabolism. A single nucleotide polymorphism (SNP) variant in human TRIB3, which results in a glutamine (Q) to arginine (R) missense mutation in a conserved motif at position 84, confers stronger Akt binding, resulting in reduced Akt phosphorylation, and is associated with a predisposition to Type 2 diabetes, cardiovascular disease, diabetic nephropathy, chronic kidney disease and leukemogenesis. Here, we used a Drosophila model to understand the importance of the conserved R residue in several Trbl functions. In the fly fat body, misexpression of a site-directed Q mutation at position R141 resulted in weakened binding to Drosophila Akt (dAkt), leading to increased levels of phospho-dAkt, increased cell and tissue size, and increases in the levels of stored glycogen and triglycerides. Consistent with the functional conservation of this arginine in modulating Akt activity, mouse Trib3 R84 misexpressed in the fly fat body blocked dAkt phosphorylation with a strength similar to wild-type Trbl. Limited mutational analysis shows that the R141 site dictates the strength of Akt binding but does not affect other Trbl-dependent developmental processes, suggesting a specificity that could serve as a drug target for metabolic diseases.
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Affiliation(s)
- Zachary Fischer
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Rahul Das
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Anna Shipman
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Jin-Yuan Fan
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Laramie Pence
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Samuel Bouyain
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
| | - Leonard L Dobens
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
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19
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An Integrative Analysis of the InR/PI3K/Akt Network Identifies the Dynamic Response to Insulin Signaling. Cell Rep 2017; 16:3062-3074. [PMID: 27626673 DOI: 10.1016/j.celrep.2016.08.029] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/21/2016] [Accepted: 08/09/2016] [Indexed: 11/20/2022] Open
Abstract
Insulin regulates an essential conserved signaling pathway affecting growth, proliferation, and metabolism. To expand our understanding of the insulin pathway, we combine biochemical, genetic, and computational approaches to build a comprehensive Drosophila InR/PI3K/Akt network. First, we map the dynamic protein-protein interaction network surrounding the insulin core pathway using bait-prey interactions connecting 566 proteins. Combining RNAi screening and phospho-specific antibodies, we find that 47% of interacting proteins affect pathway activity, and, using quantitative phosphoproteomics, we demonstrate that ∼10% of interacting proteins are regulated by insulin stimulation at the level of phosphorylation. Next, we integrate these orthogonal datasets to characterize the structure and dynamics of the insulin network at the level of protein complexes and validate our method by identifying regulatory roles for the Protein Phosphatase 2A (PP2A) and Reptin-Pontin chromatin-remodeling complexes as negative and positive regulators of ribosome biogenesis, respectively. Altogether, our study represents a comprehensive resource for the study of the evolutionary conserved insulin network.
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20
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Spatial Activation of TORC1 Is Regulated by Hedgehog and E2F1 Signaling in the Drosophila Eye. Dev Cell 2017; 42:363-375.e4. [PMID: 28829944 DOI: 10.1016/j.devcel.2017.07.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 06/17/2017] [Accepted: 07/23/2017] [Indexed: 01/20/2023]
Abstract
Target of rapamycin complex 1 (TORC1) regulates cell growth in response to nutrients and growth factors. Although TORC1 signaling has been thoroughly studied at the cellular level, the regulation of TORC1 in multicellular tissues and organs has remained elusive. Here we found that TORC1 is selectively activated in the second mitotic wave (SMW), the terminal synchronous cell division, of the developing Drosophila eye. We demonstrated that Hedgehog (Hh) signaling regulates TORC1 through E2F1 and the cyclin D/Cdk4 complex in the SMW, and this regulation is independent from insulin and amino acid signaling pathways. TORC1 is necessary for the proper G1/S transition of the cells, and the activation of TORC1 rescues the cell-cycle defect of Hh signaling-deficient cells in the SMW. Based on this evolutionarily conserved regulation of TORC1 by Hh signaling, we propose that Hh-dependent developmental signaling pathways spatially regulate TORC1 activity in multicellular organisms.
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21
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Alfa RW, Kim SK. Using Drosophila to discover mechanisms underlying type 2 diabetes. Dis Model Mech 2016; 9:365-76. [PMID: 27053133 PMCID: PMC4852505 DOI: 10.1242/dmm.023887] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mechanisms of glucose homeostasis are remarkably well conserved between the fruit flyDrosophila melanogasterand mammals. From the initial characterization of insulin signaling in the fly came the identification of downstream metabolic pathways for nutrient storage and utilization. Defects in these pathways lead to phenotypes that are analogous to diabetic states in mammals. These discoveries have stimulated interest in leveraging the fly to better understand the genetics of type 2 diabetes mellitus in humans. Type 2 diabetes results from insulin insufficiency in the context of ongoing insulin resistance. Although genetic susceptibility is thought to govern the propensity of individuals to develop type 2 diabetes mellitus under appropriate environmental conditions, many of the human genes associated with the disease in genome-wide association studies have not been functionally studied. Recent advances in the phenotyping of metabolic defects have positionedDrosophilaas an excellent model for the functional characterization of large numbers of genes associated with type 2 diabetes mellitus. Here, we examine results from studies modeling metabolic disease in the fruit fly and compare findings to proposed mechanisms for diabetic phenotypes in mammals. We provide a systematic framework for assessing the contribution of gene candidates to insulin-secretion or insulin-resistance pathways relevant to diabetes pathogenesis.
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Affiliation(s)
- Ronald W Alfa
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Neuroscience Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA Department of Medicine (Oncology), Stanford University School of Medicine, Stanford, CA 94305, USA
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22
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Cinnamon E, Makki R, Sawala A, Wickenberg LP, Blomquist GJ, Tittiger C, Paroush Z, Gould AP. Drosophila Spidey/Kar Regulates Oenocyte Growth via PI3-Kinase Signaling. PLoS Genet 2016; 12:e1006154. [PMID: 27500738 PMCID: PMC4976899 DOI: 10.1371/journal.pgen.1006154] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/08/2016] [Indexed: 11/19/2022] Open
Abstract
Cell growth and proliferation depend upon many different aspects of lipid metabolism. One key signaling pathway that is utilized in many different anabolic contexts involves Phosphatidylinositide 3-kinase (PI3K) and its membrane lipid products, the Phosphatidylinositol (3,4,5)-trisphosphates. It remains unclear, however, which other branches of lipid metabolism interact with the PI3K signaling pathway. Here, we focus on specialized fat metabolizing cells in Drosophila called larval oenocytes. In the presence of dietary nutrients, oenocytes undergo PI3K-dependent cell growth and contain very few lipid droplets. In contrast, during starvation, oenocytes decrease PI3K signaling, shut down cell growth and accumulate abundant lipid droplets. We now show that PI3K in larval oenocytes, but not in fat body cells, functions to suppress lipid droplet accumulation. Several enzymes of fatty acid, triglyceride and hydrocarbon metabolism are required in oenocytes primarily for lipid droplet induction rather than for cell growth. In contrast, a very long chain fatty-acyl-CoA reductase (FarO) and a putative lipid dehydrogenase/reductase (Spidey, also known as Kar) not only promote lipid droplet induction but also inhibit oenocyte growth. In the case of Spidey/Kar, we show that the growth suppression mechanism involves inhibition of the PI3K signaling pathway upstream of Akt activity. Together, the findings in this study show how Spidey/Kar and FarO regulate the balance between the cell growth and lipid storage of larval oenocytes. Lipids play diverse roles in health and disease. Some types of lipids function as metabolic fuels for energy homeostasis, whereas others act as components of cell membranes or serve as signals regulating cell behaviors. Much, however, remains to be discovered about the molecular connections between different categories of lipids. Phosphatidylinositide 3-kinase (PI3K) is an enzyme that synthesizes phosphatidylinositide lipids, which act as signals essential for growth during normal development and cancer. Using genetics in the fruit fly, Drosophila, we identify new regulatory links between phosphatidylinositides and lipid oxidoreductases in specialized fat-metabolizing cells called oenocytes. We find that an enzyme metabolizing very long chain fatty acids (VLCFAs) and also a putative lipid dehydrogenase/reductase both act to prevent the inappropriate overgrowth of oenocytes. In the case of the latter enzyme, it suppresses cell growth by inhibiting phosphatidylinositide signaling. Future studies will determine whether similar lipid enzymes regulate PI3K signaling in other cell and tissue types during normal development and tumorigenesis.
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Affiliation(s)
- Einat Cinnamon
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Rami Makki
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Annick Sawala
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
| | - Leah P. Wickenberg
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Gary J. Blomquist
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Claus Tittiger
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, Nevada, United States of America
| | - Ze'ev Paroush
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, the Hebrew University, Jerusalem, Israel
| | - Alex P. Gould
- The Francis Crick Institute, Mill Hill Laboratory, Mill Hill, London, United Kingdom
- * E-mail:
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23
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A hybrid model of molecular regulation and population dynamics for yeast autophagy. J Theor Biol 2016; 402:45-53. [PMID: 27103581 DOI: 10.1016/j.jtbi.2016.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/20/2016] [Accepted: 04/16/2016] [Indexed: 12/11/2022]
Abstract
Autophagy is an evolutionarily conserved lysosome-based degradation process that is involved in maintaining cellular homeostasis and stress responses. Dysregulation of autophagy is known to associate with many diseases. In this paper, we establish a Hybrid model of Molecular regulation and Population dynamics (HMP model) for yeast autophagy to study how autophagy regulation at molecular level affects the cell population dynamics under the stress of starvation. The model includes interactions between amino acids, TORC1, Atg1 complex, and Atg8 lipidation at the molecular level, and cell death and division at the cell behavior level. Two feedback loops are involved in autophagy induction, in which the negative feedback of TORC1 activation has been known previously, and the positive feedback between TORC1 and Atg1 complex formation is introduced according to the similarity of Drosophila and mammalian cells. We demonstrate that the two feedback loops play distinct roles in autophagy regulation. The positive feedback is pro-survival, whereas the negative feedback has little effect on the survival of population during starvation. In addition, autophagy deficient cells can be rescued from starvation by amino acid exchanges from their neighboring wild type cells.
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24
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Schmitt S, Ugrankar R, Greene SE, Prajapati M, Lehmann M. Drosophila Lipin interacts with insulin and TOR signaling pathways in the control of growth and lipid metabolism. J Cell Sci 2015; 128:4395-406. [PMID: 26490996 DOI: 10.1242/jcs.173740] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 10/12/2015] [Indexed: 01/20/2023] Open
Abstract
Lipin proteins have key functions in lipid metabolism, acting as both phosphatidate phosphatases (PAPs) and nuclear regulators of gene expression. We show that the insulin and TORC1 pathways independently control functions of Drosophila Lipin (dLipin). Reduced signaling through the insulin receptor strongly enhanced defects caused by dLipin deficiency in fat body development, whereas reduced signaling through TORC1 led to translocation of dLipin into the nucleus. Reduced expression of dLipin resulted in decreased signaling through the insulin-receptor-controlled PI3K-Akt pathway and increased hemolymph sugar levels. Consistent with this, downregulation of dLipin in fat body cell clones caused a strong growth defect. The PAP but not the nuclear activity of dLipin was required for normal insulin pathway activity. Reduction of other enzymes of the glycerol-3 phosphate pathway affected insulin pathway activity in a similar manner, suggesting an effect that is mediated by one or more metabolites associated with the pathway. Taken together, our data show that dLipin is subject to intricate control by the insulin and TORC1 pathways, and that the cellular status of dLipin impacts how fat body cells respond to signals relayed through the PI3K-Akt pathway.
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Affiliation(s)
- Sandra Schmitt
- Department of Biological Sciences, SCEN 601, 1 University of Arkansas, Fayetteville, AR 72701, USA
| | - Rupali Ugrankar
- Department of Biological Sciences, SCEN 601, 1 University of Arkansas, Fayetteville, AR 72701, USA
| | - Stephanie E Greene
- Department of Biological Sciences, SCEN 601, 1 University of Arkansas, Fayetteville, AR 72701, USA
| | - Meenakshi Prajapati
- Department of Biological Sciences, SCEN 601, 1 University of Arkansas, Fayetteville, AR 72701, USA
| | - Michael Lehmann
- Department of Biological Sciences, SCEN 601, 1 University of Arkansas, Fayetteville, AR 72701, USA
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25
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Fischer P, La Rosa MK, Schulz A, Preiss A, Nagel AC. Cyclin G Functions as a Positive Regulator of Growth and Metabolism in Drosophila. PLoS Genet 2015; 11:e1005440. [PMID: 26274446 PMCID: PMC4537266 DOI: 10.1371/journal.pgen.1005440] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 07/13/2015] [Indexed: 01/15/2023] Open
Abstract
In multicellular organisms, growth and proliferation is adjusted to nutritional conditions by a complex signaling network. The Insulin receptor/target of rapamycin (InR/TOR) signaling cascade plays a pivotal role in nutrient dependent growth regulation in Drosophila and mammals alike. Here we identify Cyclin G (CycG) as a regulator of growth and metabolism in Drosophila. CycG mutants have a reduced body size and weight and show signs of starvation accompanied by a disturbed fat metabolism. InR/TOR signaling activity is impaired in cycG mutants, combined with a reduced phosphorylation status of the kinase Akt1 and the downstream factors S6-kinase and eukaryotic translation initiation factor 4E binding protein (4E-BP). Moreover, the expression and accumulation of Drosophila insulin like peptides (dILPs) is disturbed in cycG mutant brains. Using a reporter assay, we show that the activity of one of the first effectors of InR signaling, Phosphoinositide 3-kinase (PI3K92E), is unaffected in cycG mutants. However, the metabolic defects and weight loss in cycG mutants were rescued by overexpression of Akt1 specifically in the fat body and by mutants in widerborst (wdb), the B'-subunit of the phosphatase PP2A, known to downregulate Akt1 by dephosphorylation. Together, our data suggest that CycG acts at the level of Akt1 to regulate growth and metabolism via PP2A in Drosophila. Size and growth of an organism are adjusted to nutritional conditions by a complex regulatory network involving the Insulin receptor and TOR signaling cascades. Drosophila melanogaster has been used in the past as a genetically tractable model to unravel the complex circuitry by genetic means. We have identified CycG as an important player in the regulation of TOR signaling. CycG mutants are underweight in the midst of food and show typical signs of TOR defects. We provide evidence that CycG acts at the level of Akt1 kinase that links the Insulin receptor and TOR signaling cascades. Molecular and genetic data point to an interplay of CycG and phosphatase PP2A, a well established negative regulator of Akt1 activity. Moreover, CycG may influence PP2A-Akt1 binding. We propose that CycG, by impeding PP2A-Akt1 interaction, acts as a positive regulator of growth in Drosophila.
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Affiliation(s)
- Patrick Fischer
- Institute of Genetics, University of Hohenheim, Stuttgart, Germany
| | | | - Adriana Schulz
- Institute of Genetics, University of Hohenheim, Stuttgart, Germany
| | - Anette Preiss
- Institute of Genetics, University of Hohenheim, Stuttgart, Germany
| | - Anja C. Nagel
- Institute of Genetics, University of Hohenheim, Stuttgart, Germany
- * E-mail:
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26
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Drosophila Longevity Assurance Conferred by Reduced Insulin Receptor Substrate Chico Partially Requires d4eBP. PLoS One 2015; 10:e0134415. [PMID: 26252766 PMCID: PMC4529185 DOI: 10.1371/journal.pone.0134415] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/08/2015] [Indexed: 12/31/2022] Open
Abstract
Mutations of the insulin/IGF signaling (IIS) pathway extend Drosophila lifespan. Based on genetic epistasis analyses, this longevity assurance is attributed to downstream effects of the FOXO transcription factor. However, as reported FOXO accounts for only a portion of the observed longevity benefit, suggesting there are additional outputs of IIS to mediate aging. One candidate is target of rapamycin complex 1 (TORC1). Reduced TORC1 activity is reported to slow aging, whereas reduced IIS is reported to repress TORC1 activity. The eukaryotic translation initiation factor 4E binding protein (4E-BP) is repressed by TORC1, and activated 4E-BP is reported to increase Drosophila lifespan. Here we use genetic epistasis analyses to test whether longevity assurance mutants of chico, the Drosophila insulin receptor substrate homolog, require Drosophila d4eBP to slow aging. In chico heterozygotes, which are robustly long-lived, d4eBP is required but not sufficient to slow aging. Remarkably, d4eBP is not required or sufficient for chico homozygotes to extend longevity. Likewise, chico heterozygote females partially require d4eBP to preserve age-dependent locomotion, and both chico genotypes require d4eBP to improve stress-resistance. Reproduction and most measures of growth affected by either chico genotype are always independent of d4eBP. In females, chico heterozygotes paradoxically produce more rather than less phosphorylated 4E-BP (p4E-BP). Altered IRS function within the IIS pathway of Drosophila appears to have partial, conditional capacity to regulate aging through an unconventional interaction with 4E-BP.
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Sopko R, Lin YB, Makhijani K, Alexander B, Perrimon N, Brückner K. A systems-level interrogation identifies regulators of Drosophila blood cell number and survival. PLoS Genet 2015; 11:e1005056. [PMID: 25749252 PMCID: PMC4352040 DOI: 10.1371/journal.pgen.1005056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 02/05/2015] [Indexed: 12/12/2022] Open
Abstract
In multicellular organisms, cell number is typically determined by a balance of intracellular signals that positively and negatively regulate cell survival and proliferation. Dissecting these signaling networks facilitates the understanding of normal development and tumorigenesis. Here, we study signaling by the Drosophila PDGF/VEGF Receptor (Pvr) in embryonic blood cells (hemocytes) and in the related cell line Kc as a model for the requirement of PDGF/VEGF receptors in vertebrate cell survival and proliferation. The system allows the investigation of downstream and parallel signaling networks, based on the ability of Pvr to activate Ras/Erk, Akt/TOR, and yet-uncharacterized signaling pathway/s, which redundantly mediate cell survival and contribute to proliferation. Using Kc cells, we performed a genome wide RNAi screen for regulators of cell number in a sensitized, Pvr deficient background. We identified the receptor tyrosine kinase (RTK) Insulin-like receptor (InR) as a major Pvr Enhancer, and the nuclear hormone receptors Ecdysone receptor (EcR) and ultraspiracle (usp), corresponding to mammalian Retinoid X Receptor (RXR), as Pvr Suppressors. In vivo analysis in the Drosophila embryo revealed a previously unrecognized role for EcR to promote apoptotic death of embryonic blood cells, which is balanced with pro-survival signaling by Pvr and InR. Phosphoproteomic analysis demonstrates distinct modes of cell number regulation by EcR and RTK signaling. We define common phosphorylation targets of Pvr and InR that include regulators of cell survival, and unique targets responsible for specialized receptor functions. Interestingly, our analysis reveals that the selection of phosphorylation targets by signaling receptors shows qualitative changes depending on the signaling status of the cell, which may have wide-reaching implications for other cell regulatory systems.
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Affiliation(s)
- Richelle Sopko
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - You Bin Lin
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Kalpana Makhijani
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Brandy Alexander
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston, Massachusetts, United States of America
| | - Katja Brückner
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, United States of America
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California, United States of America
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, United States of America
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Vachias C, Fritsch C, Pouchin P, Bardot O, Mirouse V. Tight coordination of growth and differentiation between germline and soma provides robustness for drosophila egg development. Cell Rep 2014; 9:531-41. [PMID: 25373901 DOI: 10.1016/j.celrep.2014.09.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/12/2014] [Accepted: 09/17/2014] [Indexed: 12/22/2022] Open
Abstract
Organs often need to coordinate the growth of distinct tissues during their development. Here, we analyzed the coordination between germline cysts and the surrounding follicular epithelium during Drosophila oogenesis. Genetic manipulations of the growth rate of both germline and somatic cells influence the growth of the other tissue accordingly. Growth coordination is therefore ensured by a precise, two-way, intrinsic communication. This coordination tends to maintain constant epithelial cell shape, ensuring tissue homeostasis. Moreover, this intrinsic growth coordination mechanism also provides cell differentiation synchronization. Among growth regulators, PI3-kinase and TORC1 also influence differentiation timing cell-autonomously. However, these two pathways are not regulated by the growth of the adjacent tissue, indicating that their function reflects an extrinsic and systemic influence. Altogether, our results reveal an integrated and particularly robust mechanism ensuring the spatial and temporal coordination of tissue size, cell size, and cell differentiation for the proper development of two adjacent tissues.
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Affiliation(s)
- Caroline Vachias
- GReD Laboratory, UMR CNRS 6293 - Clermont Université - INSERM U1103, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Cornelia Fritsch
- GReD Laboratory, UMR CNRS 6293 - Clermont Université - INSERM U1103, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Pierre Pouchin
- GReD Laboratory, UMR CNRS 6293 - Clermont Université - INSERM U1103, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Olivier Bardot
- GReD Laboratory, UMR CNRS 6293 - Clermont Université - INSERM U1103, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France
| | - Vincent Mirouse
- GReD Laboratory, UMR CNRS 6293 - Clermont Université - INSERM U1103, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France.
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Avet-Rochex A, Carvajal N, Christoforou CP, Yeung K, Maierbrugger KT, Hobbs C, Lalli G, Cagin U, Plachot C, McNeill H, Bateman JM. Unkempt is negatively regulated by mTOR and uncouples neuronal differentiation from growth control. PLoS Genet 2014; 10:e1004624. [PMID: 25210733 PMCID: PMC4161320 DOI: 10.1371/journal.pgen.1004624] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/23/2014] [Indexed: 01/21/2023] Open
Abstract
Neuronal differentiation is exquisitely controlled both spatially and temporally during nervous system development. Defects in the spatiotemporal control of neurogenesis cause incorrect formation of neural networks and lead to neurological disorders such as epilepsy and autism. The mTOR kinase integrates signals from mitogens, nutrients and energy levels to regulate growth, autophagy and metabolism. We previously identified the insulin receptor (InR)/mTOR pathway as a critical regulator of the timing of neuronal differentiation in the Drosophila melanogaster eye. Subsequently, this pathway has been shown to play a conserved role in regulating neurogenesis in vertebrates. However, the factors that mediate the neurogenic role of this pathway are completely unknown. To identify downstream effectors of the InR/mTOR pathway we screened transcriptional targets of mTOR for neuronal differentiation phenotypes in photoreceptor neurons. We identified the conserved gene unkempt (unk), which encodes a zinc finger/RING domain containing protein, as a negative regulator of the timing of photoreceptor differentiation. Loss of unk phenocopies InR/mTOR pathway activation and unk acts downstream of this pathway to regulate neurogenesis. In contrast to InR/mTOR signalling, unk does not regulate growth. unk therefore uncouples the role of the InR/mTOR pathway in neurogenesis from its role in growth control. We also identified the gene headcase (hdc) as a second downstream regulator of the InR/mTOR pathway controlling the timing of neurogenesis. Unk forms a complex with Hdc, and Hdc expression is regulated by unk and InR/mTOR signalling. Co-overexpression of unk and hdc completely suppresses the precocious neuronal differentiation phenotype caused by loss of Tsc1. Thus, Unk and Hdc are the first neurogenic components of the InR/mTOR pathway to be identified. Finally, we show that Unkempt-like is expressed in the developing mouse retina and in neural stem/progenitor cells, suggesting that the role of Unk in neurogenesis may be conserved in mammals. The development of a functional nervous system requires that nerve cells are generated at exactly the right time and place to be correctly integrated. Defects in the timing at which nerve cells are generated, or ‘differentiate’, lead to neurological disorders such as epilepsy and autism. However, very little is known about the identity of the genes that control the timing of nerve cell differentiation. Using developing photoreceptor nerves in the eye of the fruit fly, Drosophila, as a model, we showed previously that a molecular pathway known as ‘mTOR signalling’ is a key regulator of the timing of differentiation. In this study we have identified two new genes, unkempt and headcase, which control the timing of photoreceptor differentiation in Drosophila. The activity of unkempt and headcase is controlled by mTOR signalling and it is through these genes that mTOR is able to control nerve cell differentiation. The proteins encoded by unkempt and headcase form a complex and act synergistically to control the development of Drosophila photoreceptors. mTOR signalling controls a number of important cellular processes, but unkempt and headcase are the first components of this pathway to be identified that control nerve cell differentiation.
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Affiliation(s)
- Amélie Avet-Rochex
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Nancy Carvajal
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | | | - Kelvin Yeung
- The Lunenfeld-Tanenbaum Research Centre, Toronto, Ontario, Canada
| | - Katja T. Maierbrugger
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Carl Hobbs
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Giovanna Lalli
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Umut Cagin
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Cedric Plachot
- The Lunenfeld-Tanenbaum Research Centre, Toronto, Ontario, Canada
| | - Helen McNeill
- The Lunenfeld-Tanenbaum Research Centre, Toronto, Ontario, Canada
| | - Joseph M. Bateman
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
- * E-mail:
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Signaling pathways involved in 1-octen-3-ol-mediated neurotoxicity in Drosophila melanogaster: implication in Parkinson’s disease. Neurotox Res 2014; 25:183-91. [PMID: 23959949 DOI: 10.1007/s12640-013-9418-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 08/06/2013] [Accepted: 08/06/2013] [Indexed: 01/20/2023]
Abstract
Previously, we have pioneered Drosophila melanogaster as a reductionist model to show that 1-octen-3-ol, a musty-smelling volatile compound emitted by fungi and other organisms, causes loss of dopaminergic neurons and Parkinson’s disease-like symptoms in flies. Using our in vivo Drosophila system, the modulatory roles of important signaling pathways—JNK, Akt and the caspase-3-dependent apoptotic pathway were investigated in the context of 1-octen-3-ol-induced dopamine neurotoxicity. When heterozygous flies carrying mutant alleles for these proteins were exposed to 0.5 ppm of 1-octen-3-ol, they had shorter survival times than wild-type Drosophila. The overexpressed levels of wild-type JNK and Akt, (UAS-bsk and UAS-Akt) with TH-GAL4 and elav-GAL4 drivers improved the survival duration of exposed flies compared with controls. Thus, we found that Akt and JNK both protect against loss of dopamine activity associated with 1-octen-3-ol exposure, indicating the pro-survival role of these signaling pathways. Further, 1-octen-3-ol exposure was associated with activation of caspase 3, a hallmark for apoptosis.
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Masek P, Reynolds LA, Bollinger WL, Moody C, Mehta A, Murakami K, Yoshizawa M, Gibbs AG, Keene AC. Altered regulation of sleep and feeding contributes to starvation resistance in Drosophila melanogaster. ACTA ACUST UNITED AC 2014; 217:3122-32. [PMID: 24948636 DOI: 10.1242/jeb.103309] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Animals respond to changes in food availability by adjusting sleep and foraging strategies to optimize their fitness. Wild populations of the fruit fly, Drosophila melanogaster, display highly variable levels of starvation resistance that are dependent on geographic location, food availability and evolutionary history. How behaviors that include sleep and feeding vary in Drosophila with increased starvation resistance is unclear. We have generated starvation-resistant flies through experimental evolution to investigate the relationship between foraging behaviors and starvation resistance. Outbred populations of D. melanogaster were selected for starvation resistance over 60 generations. This selection process resulted in flies with a threefold increase in total lipids that survive up to 18 days without food. We tested starvation-selected (S) flies for sleep and feeding behaviors to determine the effect that selection for starvation resistance has had on foraging behavior. Flies from three replicated starvation-selected populations displayed a dramatic reduction in feeding and prolonged sleep duration compared to fed control (F) populations, suggesting that modified sleep and feeding may contribute to starvation resistance. A prolonged larval developmental period contributes to the elevated energy stores present in starvation-selected flies. By preventing S larvae from feeding longer than F larvae, we were able to reduce energy stores in adult S flies to the levels seen in adult F flies, thus allowing us to control for energy storage levels. However, the reduction of energy stores in S flies fails to generate normal sleep and feeding behavior seen in F flies with similar energy stores. These findings suggest that the behavioral changes observed in S flies are due to genetic regulation of behavior rather than elevated lipid levels. Testing S-F hybrid individuals for both feeding and sleep revealed a lack of correlation between food consumption and sleep duration, indicating further independence in genetic factors underlying the sleep and feeding changes observed in S flies. Taken together, these findings provide evidence that starvation selection results in prolonged sleep and reduced feeding through a mechanism that is independent of elevated energy stores. These findings suggest that changes in both metabolic function and behavior contribute to the increase in starvation resistance seen in flies selected for starvation resistance.
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Affiliation(s)
- Pavel Masek
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
| | - Lauren A Reynolds
- School of Life Sciences, University of Nevada, Las Vegas, NV, 89154, USA
| | | | - Catriona Moody
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
| | - Aradhana Mehta
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
| | - Kazuma Murakami
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
| | - Masato Yoshizawa
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
| | - Allen G Gibbs
- School of Life Sciences, University of Nevada, Las Vegas, NV, 89154, USA
| | - Alex C Keene
- Department of Biology, University of Nevada, Reno. Reno, NV, 89557, USA
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Chuang CL, Lu YN, Wang HC, Chang HY. Genetic dissection reveals that Akt is the critical kinase downstream of LRRK2 to phosphorylate and inhibit FOXO1, and promotes neuron survival. Hum Mol Genet 2014; 23:5649-58. [PMID: 24916379 DOI: 10.1093/hmg/ddu281] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Leucine-rich repeat kinase 2 (LRRK2) is a complex kinase and mutations in LRRK2 are perhaps the most common genetic cause of Parkinson's disease (PD). However, the identification of the normal physiological function of LRRK2 remains elusive. Here, we show that LRRK2 protects neurons against apoptosis induced by the Drosophila genes grim, hid and reaper. Genetic dissection reveals that Akt is the critical downstream kinase of LRRK2 that phosphorylates and inhibits FOXO1, and thereby promotes survival. Like human LRRK2, Drosophila lrrk also promotes neuron survival; lrrk loss-of-function mutant displays reduced cell numbers, which can be rescued by LRRK2 expression. Importantly, LRRK2 G2019S and LRRK2 R1441C mutants impair the ability of LRRK2 to activate Akt, and fail to prevent apoptotic death. Ectopic expression of a constitutive active form of Akt hence is sufficient to rescue this functional deficit. These data establish that LRRK2 can protect neurons from apoptotic insult through a survival pathway in which LRRK2 signals to activate Akt, and then inhibits FOXO1. These results might indicate that a LRRK-Akt therapeutic pathway to promote neuron survival and to prevent neurodegeneration in Parkinson's disease.
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Affiliation(s)
- Chia-Lung Chuang
- Institute of Systems Neuroscience, Department of Medical Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan and Brain Research Center, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - Yu-Ning Lu
- Institute of Systems Neuroscience, Department of Medical Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan and Brain Research Center, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - Hung-Cheng Wang
- Institute of Systems Neuroscience, Department of Medical Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan and Brain Research Center, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - Hui-Yun Chang
- Institute of Systems Neuroscience, Department of Medical Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan and Brain Research Center, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
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Nowak K, Seisenbacher G, Hafen E, Stocker H. Nutrient restriction enhances the proliferative potential of cells lacking the tumor suppressor PTEN in mitotic tissues. eLife 2013; 2:e00380. [PMID: 23853709 PMCID: PMC3707060 DOI: 10.7554/elife.00380] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 06/06/2013] [Indexed: 01/20/2023] Open
Abstract
How single cells in a mitotic tissue progressively acquire hallmarks of cancer is poorly understood. We exploited mitotic recombination in developing Drosophila imaginal tissues to analyze the behavior of cells devoid of the tumor suppressor PTEN, a negative regulator of PI3K signaling, under varying nutritional conditions. Cells lacking PTEN strongly overproliferated specifically in nutrient restricted larvae. Although the PTEN mutant cells were sensitive to starvation, they successfully competed with neighboring cells by autonomous and non-autonomous mechanisms distinct from cell competition. The overgrowth was strictly dependent on the activity of the downstream components Akt/PKB and TORC1, and a reduction in amino acid uptake by reducing the levels of the amino acid transporter Slimfast caused clones of PTEN mutant cells to collapse. Our findings demonstrate how limiting nutritional conditions impact on cells lacking the tumor suppressor PTEN to cause hyperplastic overgrowth. DOI:http://dx.doi.org/10.7554/eLife.00380.001 Mutations are permanent changes to a cell’s genome. If one or more mutations result in a cell proliferating in an unregulated manner, it is referred to as a cancer cell. The generation of cancer cells is a relatively common occurrence within organisms, but these rogue cells are generally recognized and destroyed by the organism’s immune system. However, when the immune system fails to identify and eliminate cancer cells, they can proliferate to form malignant, life-threatening tumors. Mutations in a gene called PTEN are often found within cells that develop into cancerous tumors. This gene is normally expressed as a protein that is involved in the regulation of cell division, preventing cells from growing and dividing too quickly. However, when the protein PTEN is absent or non-functional, cells experience enhanced growth, proliferation, and survival. Such cells are also thought to be resistant to nutrient restriction, but the mechanism responsible for this resistance is not well understood. Here, Nowak et al. investigate the behavior of cells lacking PTEN in a fly model under a variety of nutritional conditions. When the supply of nutrients is limited, cells lacking PTEN shift resources from cell growth to cell multiplication. This appears to allow PTEN-deficient cells to outcompete neighboring wild-type cells; Nowak et al. suggest these rapidly proliferating cells are capable of effectively hoarding nutrient stores, both in their immediate vicinity and organism-wide. Further studies that focus on changes in gene expression may be able to uncover the mechanism that allows PTEN-deficient cells to proliferate when nutrients are restricted. Moreover, by shedding light on a factor that has an important influence on tumor development, these results may have implications for cancer treatment strategies. DOI:http://dx.doi.org/10.7554/eLife.00380.002
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Affiliation(s)
- Katarzyna Nowak
- Institute of Molecular Systems Biology , ETH Zürich , Zürich , Switzerland
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Natarajan R, Trivedi-Vyas D, Wairkar YP. Tuberous sclerosis complex regulates Drosophila neuromuscular junction growth via the TORC2/Akt pathway. Hum Mol Genet 2013; 22:2010-23. [PMID: 23393158 DOI: 10.1093/hmg/ddt053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mutations in the tuberous sclerosis complex (TSC) are associated with various forms of neurodevelopmental disorders, including autism and epilepsy. The heterodimeric TSC complex, consisting of Tsc1 and Tsc2 proteins, regulates the activity of the TOR (target of rapamycin) complex via Rheb, a small GTPase. TOR, an atypical serine/threonine kinase, forms two distinct complexes TORC1 and TORC2. Raptor and Rictor serve as specific functional components of TORC1 and TORC2, respectively. Previous studies have identified Tsc1 as a regulator of hippocampal neuronal morphology and function via the TOR pathway, but it is unclear whether this is mediated via TORC1 or TORC2. In a genetic screen for aberrant synaptic growth at the neuromuscular junctions (NMJs) in Drosophila, we identified that Tsc2 mutants showed increased synaptic growth. Increased synaptic growth was also observed in rictor mutants, while raptor knockdown did not phenocopy the TSC mutant phenotype, suggesting that a novel role exists for TORC2 in regulating synapse growth. Furthermore, Tsc2 mutants showed a dramatic decrease in the levels of phosphorylated Akt, and interestingly, Akt mutants phenocopied Tsc2 mutants, leading to the hypothesis that Tsc2 and Akt might work via the same genetic pathway to regulate synapse growth. Indeed, transheterozygous analysis of Tsc2 and Akt mutants confirmed this hypothesis. Finally, our data also suggest that while overexpression of rheb results in aberrant synaptic overgrowth, the overgrowth might be independent of TORC2. Thus, we propose that at the Drosophila NMJ, TSC regulates synaptic growth via the TORC2-Akt pathway.
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Affiliation(s)
- Rajalaxmi Natarajan
- Department of Neurology, and George and Cynthia Mitchell Center for Neurodegenerative Diseases, University ofTexas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA
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Papatheodorou I, Ziehm M, Wieser D, Alic N, Partridge L, Thornton JM. Using answer set programming to integrate RNA expression with signalling pathway information to infer how mutations affect ageing. PLoS One 2012; 7:e50881. [PMID: 23251396 PMCID: PMC3519537 DOI: 10.1371/journal.pone.0050881] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/25/2012] [Indexed: 01/03/2023] Open
Abstract
A challenge of systems biology is to integrate incomplete knowledge on pathways with existing experimental data sets and relate these to measured phenotypes. Research on ageing often generates such incomplete data, creating difficulties in integrating RNA expression with information about biological processes and the phenotypes of ageing, including longevity. Here, we develop a logic-based method that employs Answer Set Programming, and use it to infer signalling effects of genetic perturbations, based on a model of the insulin signalling pathway. We apply our method to RNA expression data from Drosophila mutants in the insulin pathway that alter lifespan, in a foxo dependent fashion. We use this information to deduce how the pathway influences lifespan in the mutant animals. We also develop a method for inferring the largest common sub-paths within each of our signalling predictions. Our comparisons reveal consistent homeostatic mechanisms across both long- and short-lived mutants. The transcriptional changes observed in each mutation usually provide negative feedback to signalling predicted for that mutation. We also identify an S6K-mediated feedback in two long-lived mutants that suggests a crosstalk between these pathways in mutants of the insulin pathway, in vivo. By formulating the problem as a logic-based theory in a qualitative fashion, we are able to use the efficient search facilities of Answer Set Programming, allowing us to explore larger pathways, combine molecular changes with pathways and phenotype and infer effects on signalling in in vivo, whole-organism, mutants, where direct signalling stimulation assays are difficult to perform. Our methods are available in the web-service NetEffects: http://www.ebi.ac.uk/thornton-srv/software/NetEffects.
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Affiliation(s)
- Irene Papatheodorou
- European Molecular Biology Laboratory-European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom.
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Detrimental effects of proteasome inhibition activity in Drosophila melanogaster: implication of ER stress, autophagy, and apoptosis. Cell Biol Toxicol 2012; 29:13-37. [PMID: 23161111 DOI: 10.1007/s10565-012-9235-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 11/05/2012] [Indexed: 12/27/2022]
Abstract
In eukaryotes, the ubiquitin-proteasome machinery regulates a number of fundamental cellular processes through accurate and tightly controlled protein degradation pathways. We have, herein, examined the effects of proteasome functional disruption in Dmp53 (+/+) (wild-type) and Dmp53 (-/-) Drosophila melanogaster fly strains through utilization of Bortezomib, a proteasome-specific inhibitor. We report that proteasome inhibition drastically shortens fly life-span and impairs climbing performance, while it also causes larval lethality and activates developmentally irregular cell death programs during oogenesis. Interestingly, Dmp53 gene seems to play a role in fly longevity and climbing ability. Moreover, Bortezomib proved to induce endoplasmic reticulum (ER) stress that was able to result in the engagement of unfolded protein response (UPR) signaling pathway, as respectively indicated by fly Xbp1 activation and Ref(2)P-containing protein aggregate formation. Larva salivary gland and adult brain both underwent strong ER stress in response to Bortezomib, thus underscoring the detrimental role of proteasome inhibition in larval development and brain function. We also propose that the observed upregulation of autophagy operates as a protective mechanism to "counterbalance" Bortezomib-induced systemic toxicity, which is tightly associated, besides ER stress, with activation of apoptosis, mainly mediated by functional Drice caspase and deregulated dAkt kinase. The reduced life-span of exposed to Bortezomib flies overexpressing Atg1_RNAi or Atg18_RNAi supports the protective nature of autophagy against proteasome inhibition-induced stress. Our data reveal the in vivo significance of proteasome functional integrity as a major defensive system against cellular toxicity likely occurring during critical biological processes and morphogenetic courses.
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Zitserman D, Gupta S, Kruger WD, Karbowniczek M, Roegiers F. The TSC1/2 complex controls Drosophila pigmentation through TORC1-dependent regulation of catecholamine biosynthesis. PLoS One 2012; 7:e48720. [PMID: 23144943 PMCID: PMC3492411 DOI: 10.1371/journal.pone.0048720] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/27/2012] [Indexed: 02/05/2023] Open
Abstract
In Drosophila, the pattern of adult pigmentation is initiated during late pupal stages by the production of catecholamines DOPA and dopamine, which are converted to melanin. The pattern and degree of melanin deposition is controlled by the expression of genes such as ebony and yellow as well as by the enzymes involved in catecholamine biosynthesis. In this study, we show that the conserved TSC/TORC1 cell growth pathway controls catecholamine biosynthesis in Drosophila during pigmentation. We find that high levels of Rheb, an activator of the TORC1 complex, promote premature pigmentation in the mechanosensory bristles during pupal stages, and alter pigmentation in the cuticle of the adult fly. Disrupting either melanin synthesis by RNAi knockdown of melanogenic enzymes such as tyrosine hydroxylase (TH), or downregulating TORC1 activity by Raptor knockdown, suppresses the Rheb-dependent pigmentation phenotype in vivo. Increased Rheb activity drives pigmentation by increasing levels of TH in epidermal cells. Our findings indicate that control of pigmentation is linked to the cellular nutrient-sensing pathway by regulating levels of a critical enzyme in melanogenesis, providing further evidence that inappropriate activation of TORC1, a hallmark of the human tuberous sclerosis complex tumor syndrome disorder, can alter metabolic and differentiation pathways in unexpected ways.
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Affiliation(s)
- Diana Zitserman
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Sapna Gupta
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | - Warren D. Kruger
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
| | | | - Fabrice Roegiers
- Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Dragojlovic-Munther M, Martinez-Agosto JA. Multifaceted roles of PTEN and TSC orchestrate growth and differentiation of Drosophila blood progenitors. Development 2012; 139:3752-63. [PMID: 22951642 DOI: 10.1242/dev.074203] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The innate plasticity of hematopoietic progenitors is tightly regulated to supply blood cells during normal hematopoiesis and in response to stress or infection. We demonstrate that in the Drosophila lymph gland (LG) the tumor suppressors TSC and PTEN control blood progenitor proliferation through a common TOR- and 4EBP-dependent pathway. Tsc2 or Pten deficiency in progenitors increases TOR signaling and causes LG overgrowth by increasing the number of actively dividing cells that accumulate high levels of phosphorylated (p) 4EBP during a critical window of growth. These phenotypes are associated with increased reactive oxygen species (ROS) levels in the LG, and scavenging ROS in progenitors is sufficient to rescue overgrowth. Blood progenitor number is also sensitive to starvation and hypoxia in a TOR-dependent manner. Differences between Tsc1/2 and Pten function become apparent at later stages. Loss of Tsc1/2 autonomously increases p4EBP and decreases pAKT levels, expands the number of intermediate progenitors and limits terminal differentiation, except for a late induction of lamellocytes. By contrast, absence of PTEN increases p4EBP and pAKT levels and induces myeloproliferative expansion of plasmatocytes and crystal cells. This increased malignancy is associated with non-autonomous increases in p4EBP levels within peripheral differentiating hemocytes, culminating in their premature release into circulation and demonstrating potential non-autonomous effects of Pten dysfunction on malignancy. This study highlights mechanistic differences between TSC and PTEN on TOR function and demonstrates the multifaceted roles of a nutrient-sensing pathway in orchestrating proliferation and differentiation of myeloid-specific blood progenitors through regulation of ROS levels and the resulting myeloproliferative disorder when dysregulated.
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Perrin AJ, Gunda M, Yu B, Yen K, Ito S, Forster S, Tissenbaum HA, Derry WB. Noncanonical control of C. elegans germline apoptosis by the insulin/IGF-1 and Ras/MAPK signaling pathways. Cell Death Differ 2012; 20:97-107. [PMID: 22935616 DOI: 10.1038/cdd.2012.101] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The insulin/IGF-1 pathway controls a number of physiological processes in the nematode worm Caenorhabditis elegans, including development, aging and stress response. We previously found that the Akt/PKB ortholog AKT-1 dampens the apoptotic response to genotoxic stress in the germline by negatively regulating the p53-like transcription factor CEP-1. Here, we report unexpected rearrangements to the insulin/IGF-1 pathway, whereby the insulin-like receptor DAF-2 and 3-phosphoinositide-dependent protein kinase PDK-1 oppose AKT-1 to promote DNA damage-induced apoptosis. While DNA damage does not affect phosphorylation at the PDK-1 site Thr350/Thr308 of AKT-1, it increased phosphorylation at Ser517/Ser473. Although ablation of daf-2 or pdk-1 completely suppressed akt-1-dependent apoptosis, the transcriptional activation of CEP-1 was unaffected, suggesting that daf-2 and pdk-1 act independently or downstream of cep-1 and akt-1. Ablation of the akt-1 paralog akt-2 or the downstream target of the insulin/IGF-1 pathway daf-16 (a FOXO transcription factor) restored sensitivity to damage-induced apoptosis in daf-2 and pdk-1 mutants. In addition, daf-2 and pdk-1 mutants have reduced levels of phospho-MPK-1/ERK in their germ cells, indicating that the insulin/IGF-1 pathway promotes Ras signaling in the germline. Ablation of the Ras effector gla-3, a negative regulator of mpk-1, restored sensitivity to apoptosis in daf-2 mutants, suggesting that gla-3 acts downstream of daf-2. In addition, the hypersensitivity of let-60/Ras gain-of-function mutants to damage-induced apoptosis was suppressed to wild-type levels by ablation of daf-2. Thus, insulin/IGF-1 signaling selectively engages AKT-2/DAF-16 to promote DNA damage-induced germ cell apoptosis downstream of CEP-1 through the Ras pathway.
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Affiliation(s)
- A J Perrin
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada
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40
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Insulin/IGF signaling drives cell proliferation in part via Yorkie/YAP. Dev Biol 2012; 367:187-96. [DOI: 10.1016/j.ydbio.2012.05.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/01/2012] [Accepted: 05/03/2012] [Indexed: 12/12/2022]
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41
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Justiniano SE, Mathew A, Mitra S, Manivannan SN, Simcox A. Loss of the tumor suppressor Pten promotes proliferation of Drosophila melanogaster cells in vitro and gives rise to continuous cell lines. PLoS One 2012; 7:e31417. [PMID: 22363644 PMCID: PMC3283623 DOI: 10.1371/journal.pone.0031417] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 01/06/2012] [Indexed: 11/18/2022] Open
Abstract
In vivo analysis of Drosophila melanogaster has enhanced our understanding of many biological processes, notably the mechanisms of heredity and development. While in vivo analysis of mutants has been a strength of the field, analyzing fly cells in culture is valuable for cell biological, biochemical and whole genome approaches in which large numbers of homogeneous cells are required. An efficient genetic method to derive Drosophila cell lines using expression of an oncogenic form of Ras (Ras(V12)) has been developed. Mutations in tumor suppressors, which are known to cause cell hyperproliferation in vivo, could provide another method for generating Drosophila cell lines. Here we screened Drosophila tumor suppressor mutations to test if they promoted cell proliferation in vitro. We generated primary cultures and determined when patches of proliferating cells first emerged. These cells emerged on average at 37 days in wild-type cultures. Using this assay we found that a Pten mutation had a strong effect. Patches of proliferating cells appeared on average at 11 days and the cultures became confluent in about 3 weeks, which is similar to the timeframe for cultures expressing Ras(V12). Three Pten mutant cell lines were generated and these have now been cultured for between 250 and 630 cell doublings suggesting the life of the mutant cells is likely to be indefinite. We conclude that the use of Pten mutants is a powerful means to derive new Drosophila cell lines.
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Affiliation(s)
- Steven E. Justiniano
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Anne Mathew
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Sayan Mitra
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Sathiya N. Manivannan
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Amanda Simcox
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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42
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Diet and energy-sensing inputs affect TorC1-mediated axon misrouting but not TorC2-directed synapse growth in a Drosophila model of tuberous sclerosis. PLoS One 2012; 7:e30722. [PMID: 22319582 PMCID: PMC3272037 DOI: 10.1371/journal.pone.0030722] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 12/21/2011] [Indexed: 11/19/2022] Open
Abstract
The Target of Rapamycin (TOR) growth regulatory system is influenced by a number of different inputs, including growth factor signaling, nutrient availability, and cellular energy levels. While the effects of TOR on cell and organismal growth have been well characterized, this pathway also has profound effects on neural development and behavior. Hyperactivation of the TOR pathway by mutations in the upstream TOR inhibitors TSC1 (tuberous sclerosis complex 1) or TSC2 promotes benign tumors and neurological and behavioral deficits, a syndrome known as tuberous sclerosis (TS). In Drosophila, neuron-specific overexpression of Rheb, the direct downstream target inhibited by Tsc1/Tsc2, produced significant synapse overgrowth, axon misrouting, and phototaxis deficits. To understand how misregulation of Tor signaling affects neural and behavioral development, we examined the influence of growth factor, nutrient, and energy sensing inputs on these neurodevelopmental phenotypes. Neural expression of Pi3K, a principal mediator of growth factor inputs to Tor, caused synapse overgrowth similar to Rheb, but did not disrupt axon guidance or phototaxis. Dietary restriction rescued Rheb-mediated behavioral and axon guidance deficits, as did overexpression of AMPK, a component of the cellular energy sensing pathway, but neither was able to rescue synapse overgrowth. While axon guidance and behavioral phenotypes were affected by altering the function of a Tor complex 1 (TorC1) component, Raptor, or a TORC1 downstream element (S6k), synapse overgrowth was only suppressed by reducing the function of Tor complex 2 (TorC2) components (Rictor, Sin1). These findings demonstrate that different inputs to Tor signaling have distinct activities in nervous system development, and that Tor provides an important connection between nutrient-energy sensing systems and patterning of the nervous system.
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Thomson TC, Schneemann A, Johnson J. Oocyte destruction is activated during viral infection. Genesis 2012; 50:453-65. [PMID: 22173880 DOI: 10.1002/dvg.22004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 11/30/2011] [Accepted: 12/11/2011] [Indexed: 11/10/2022]
Abstract
Viral infection has been associated with a starvation-like state in Drosophila melanogaster. Because starvation and inhibiting TOR kinase activity in vivo result in blocked oocyte production, we hypothesized that viral infection would also result in compromised oogenesis. Wild-type flies were injected with flock house virus (FHV) and survival and embryo production were monitored. Infected flies had a dose-responsive loss of fecundity that corresponded to a global reduction in Akt/TOR signaling. Highly penetrant egg chamber destruction mid-way through oogenesis was noted and FHV coat protein was detected within developing egg chambers. As seen with in vivo TOR inhibition, oogenesis was partially rescued in loss of function discs large and merlin mutants. As expected, mutants in genes known to be involved in virus internalization and trafficking [Clathrin heavy chain (chc) and synaptotagmin] survive longer during infection. However, oogenesis was rescued only in chc mutants. This suggests that viral response mechanisms that control fly survival and egg chamber survival are separable. The genetic and signaling requirements for oocyte destruction delineated here represent a novel host-virus interaction with implications for the control of both fly and virus populations.
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Affiliation(s)
- Travis C Thomson
- Department of Obstetrics, Gynecology, and Reproductive Sciences/Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, Connecticut, USA
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van Dam TJP, Zwartkruis FJT, Bos JL, Snel B. Evolution of the TOR pathway. J Mol Evol 2011; 73:209-20. [PMID: 22057117 PMCID: PMC3236823 DOI: 10.1007/s00239-011-9469-9] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 10/24/2011] [Indexed: 11/27/2022]
Abstract
The TOR kinase is a major regulator of growth in eukaryotes. Many components of the TOR pathway are implicated in cancer and metabolic diseases in humans. Analysis of the evolution of TOR and its pathway may provide fundamental insight into the evolution of growth regulation in eukaryotes and provide a practical framework on which experimental evidence can be compared between species. Here we performed phylogenetic analyses on the components of the TOR pathway and determined their point of invention. We find that the two TOR complexes and a large part of the TOR pathway originated before the Last Eukaryotic Common Ancestor and form a core to which new inputs have been added during animal evolution. In addition, we provide insight into how duplications and sub-functionalization of the S6K, RSK, SGK and PKB kinases shaped the complexity of the TOR pathway. In yeast we identify novel AGC kinases that are orthologous to the S6 kinase. These results demonstrate how a vital signaling pathway can be both highly conserved and flexible in eukaryotes.
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Affiliation(s)
- Teunis J P van Dam
- Theoretical Biology and Bioinformatics, Department of Biology, Science Faculty, Utrecht University, Padualaan 8, Utrecht, The Netherlands.
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Friedman AA, Tucker G, Singh R, Yan D, Vinayagam A, Hu Y, Binari R, Hong P, Sun X, Porto M, Pacifico S, Murali T, Finley RL, Asara JM, Berger B, Perrimon N. Proteomic and functional genomic landscape of receptor tyrosine kinase and ras to extracellular signal-regulated kinase signaling. Sci Signal 2011; 4:rs10. [PMID: 22028469 DOI: 10.1126/scisignal.2002029] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Characterizing the extent and logic of signaling networks is essential to understanding specificity in such physiological and pathophysiological contexts as cell fate decisions and mechanisms of oncogenesis and resistance to chemotherapy. Cell-based RNA interference (RNAi) screens enable the inference of large numbers of genes that regulate signaling pathways, but these screens cannot provide network structure directly. We describe an integrated network around the canonical receptor tyrosine kinase (RTK)-Ras-extracellular signal-regulated kinase (ERK) signaling pathway, generated by combining parallel genome-wide RNAi screens with protein-protein interaction (PPI) mapping by tandem affinity purification-mass spectrometry. We found that only a small fraction of the total number of PPI or RNAi screen hits was isolated under all conditions tested and that most of these represented the known canonical pathway components, suggesting that much of the core canonical ERK pathway is known. Because most of the newly identified regulators are likely cell type- and RTK-specific, our analysis provides a resource for understanding how output through this clinically relevant pathway is regulated in different contexts. We report in vivo roles for several of the previously unknown regulators, including CG10289 and PpV, the Drosophila orthologs of two components of the serine/threonine-protein phosphatase 6 complex; the Drosophila ortholog of TepIV, a glycophosphatidylinositol-linked protein mutated in human cancers; CG6453, a noncatalytic subunit of glucosidase II; and Rtf1, a histone methyltransferase.
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Affiliation(s)
- Adam A Friedman
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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46
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Anaplastic lymphoma kinase spares organ growth during nutrient restriction in Drosophila. Cell 2011; 146:435-47. [PMID: 21816278 DOI: 10.1016/j.cell.2011.06.040] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 12/24/2010] [Accepted: 06/16/2011] [Indexed: 11/24/2022]
Abstract
Developing animals survive periods of starvation by protecting the growth of critical organs at the expense of other tissues. Here, we use Drosophila to explore the as yet unknown mechanisms regulating this privileged tissue growth. As in mammals, we observe in Drosophila that the CNS is more highly spared than other tissues during nutrient restriction (NR). We demonstrate that anaplastic lymphoma kinase (Alk) efficiently protects neural progenitor (neuroblast) growth against reductions in amino acids and insulin-like peptides during NR via two mechanisms. First, Alk suppresses the growth requirement for amino acid sensing via Slimfast/Rheb/TOR complex 1. And second, Alk, rather than insulin-like receptor, primarily activates PI3-kinase. Alk maintains PI3-kinase signaling during NR as its ligand, Jelly belly (Jeb), is constitutively expressed from a glial cell niche surrounding neuroblasts. Together, these findings identify a brain-sparing mechanism that shares some regulatory features with the starvation-resistant growth programs of mammalian tumors.
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Abstract
Drosophila melanogaster has a long history as a model organism with several unique features that make it an ideal research tool for the study of the relationship between genotype and phenotype. Importantly fundamental genetic principles as well as key human disease genes have been uncovered through the use of Drosophila. The contribution of the fruit fly to science and medicine continues in the postgenomic era as cell-based Drosophila RNAi screens are a cost-effective and scalable enabling technology that can be used to quantify the contribution of different genes to diverse cellular processes. Drosophila high-throughput screens can also be used as integral part of systems-level approaches to describe the architecture and dynamics of cellular networks.
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Affiliation(s)
- Chris Bakal
- Dynamical Cell Systems Laboratory, Division of Cancer Biology, The Institute of Cancer Research, London, UK.
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48
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Jiang M, Instrell R, Saunders B, Berven H, Howell M. Tales from an academic RNAi screening facility; FAQs. Brief Funct Genomics 2011; 10:227-37. [PMID: 21527443 DOI: 10.1093/bfgp/elr016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
RNAi technology is now a well-established and widely employed research technique that has been adopted by many researchers for use in large-scale screening campaigns. Here, we offer our experience of genome-wide siRNA screening from the perspective of a facility providing screening as a service to a wide range of researchers with diverse interests and approaches. We have experienced the emotional rollercoaster of screening from the exuberant early promise of a screen, the messy reality of the data through to the recognition of screen data as a potential information goldmine. Here, we use some of the questions we most frequently encounter to highlight the initial concerns of many researchers embarking on a siRNA screen and conclude that an informed view of what can be reasonably expected from a screen is essential to the most effective implementation of the technology. Along the way, we suggest that for this area of research at least, either centralization of the resources or close and open collaboration between interested parties offers distinct advantages.
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Affiliation(s)
- Ming Jiang
- High-Throughput Screening facility, Cancer Research UK, London Research Institute
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49
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McCormick MA, Tsai SY, Kennedy BK. TOR and ageing: a complex pathway for a complex process. Philos Trans R Soc Lond B Biol Sci 2011; 366:17-27. [PMID: 21115526 DOI: 10.1098/rstb.2010.0198] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Studies in invertebrate model organisms have led to a wealth of knowledge concerning the ageing process. But which of these discoveries will apply to ageing in humans? Recently, an assessment of the degree of conservation of ageing pathways between two of the leading invertebrate model organisms, Saccharomyces cerevisiae and Caenorhabditis elegans, was completed. The results (i) quantitatively indicated that pathways were conserved between evolutionarily disparate invertebrate species and (ii) emphasized the importance of the TOR kinase pathway in ageing. With recent findings that deletion of the mTOR substrate S6K1 or exposure of mice to the mTOR inhibitor rapamycin result in lifespan extension, mTOR signalling has become a major focus of ageing research. Here, we address downstream targets of mTOR signalling and their possible links to ageing. We also briefly cover other ageing genes identified by comparing worms and yeast, addressing the likelihood that their mammalian counterparts will affect longevity.
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Affiliation(s)
- Mark A McCormick
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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50
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Chell JM, Brand AH. Nutrition-responsive glia control exit of neural stem cells from quiescence. Cell 2011; 143:1161-73. [PMID: 21183078 PMCID: PMC3087489 DOI: 10.1016/j.cell.2010.12.007] [Citation(s) in RCA: 284] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 11/17/2010] [Accepted: 12/07/2010] [Indexed: 11/28/2022]
Abstract
The systemic regulation of stem cells ensures that they meet the needs of the organism during growth and in response to injury. A key point of regulation is the decision between quiescence and proliferation. During development, Drosophila neural stem cells (neuroblasts) transit through a period of quiescence separating distinct embryonic and postembryonic phases of proliferation. It is known that neuroblasts exit quiescence via a hitherto unknown pathway in response to a nutrition-dependent signal from the fat body. We have identified a population of glial cells that produce insulin/IGF-like peptides in response to nutrition, and we show that the insulin/IGF receptor pathway is necessary for neuroblasts to exit quiescence. The forced expression of insulin/IGF-like peptides in glia, or activation of PI3K/Akt signaling in neuroblasts, can drive neuroblast growth and proliferation in the absence of dietary protein and thus uncouple neuroblasts from systemic control.
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Affiliation(s)
- James M Chell
- The Gurdon Institute and Department of Physiology, Development, and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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