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Sidisky JM, Winters A, Caratenuto R, Babcock DT. Synaptic defects in a drosophila model of muscular dystrophy. Front Cell Neurosci 2024; 18:1381112. [PMID: 38812789 PMCID: PMC11133739 DOI: 10.3389/fncel.2024.1381112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 04/08/2024] [Indexed: 05/31/2024] Open
Abstract
Muscular dystrophies are a devastating class of diseases that result in a progressive loss of muscle integrity. Duchenne Muscular Dystrophy, the most prevalent form of Muscular Dystrophy, is due to the loss of functional Dystrophin. While much is known regarding destruction of muscle tissue in these diseases, much less is known regarding the synaptic defects that also occur in these diseases. Synaptic defects are also among the earliest hallmarks of neurodegenerative diseases, including the neuromuscular disease Amyotrophic Lateral Sclerosis (ALS). Our current study investigates synaptic defects within adult muscle tissues as well as presynaptic motor neurons in Drosophila dystrophin mutants. Here we demonstrate that the progressive, age-dependent loss of flight ability in dystrophin mutants is accompanied by disorganization of Neuromuscular Junctions (NMJs), including impaired localization of both presynaptic and postsynaptic markers. We show that these synaptic defects, including presynaptic defects within motor neurons, are due to the loss of Dystrophin specifically within muscles. These results should help to better understand the early synaptic defects preceding cell loss in neuromuscular disorders.
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Affiliation(s)
- Jessica M. Sidisky
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Cambridge, MA, United States
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Alex Winters
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States
| | - Russell Caratenuto
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States
| | - Daniel T. Babcock
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, United States
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2
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Koff M, Monagas-Valentin P, Novikov B, Chandel I, Panin V. Protein O-mannosylation: one sugar, several pathways, many functions. Glycobiology 2023; 33:911-926. [PMID: 37565810 PMCID: PMC10859634 DOI: 10.1093/glycob/cwad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 07/23/2023] [Accepted: 07/31/2023] [Indexed: 08/12/2023] Open
Abstract
Recent research has unveiled numerous important functions of protein glycosylation in development, homeostasis, and diseases. A type of glycosylation taking the center stage is protein O-mannosylation, a posttranslational modification conserved in a wide range of organisms, from yeast to humans. In animals, protein O-mannosylation plays a crucial role in the nervous system, whereas protein O-mannosylation defects cause severe neurological abnormalities and congenital muscular dystrophies. However, the molecular and cellular mechanisms underlying protein O-mannosylation functions and biosynthesis remain not well understood. This review outlines recent studies on protein O-mannosylation while focusing on the functions in the nervous system, summarizes the current knowledge about protein O-mannosylation biosynthesis, and discusses the pathologies associated with protein O-mannosylation defects. The evolutionary perspective revealed by studies in the Drosophila model system are also highlighted. Finally, the review touches upon important knowledge gaps in the field and discusses critical questions for future research on the molecular and cellular mechanisms associated with protein O-mannosylation functions.
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Affiliation(s)
- Melissa Koff
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, College Station, TX 77843, United States
| | - Pedro Monagas-Valentin
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, College Station, TX 77843, United States
| | - Boris Novikov
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, College Station, TX 77843, United States
| | - Ishita Chandel
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, College Station, TX 77843, United States
| | - Vladislav Panin
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, College Station, TX 77843, United States
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Li X, Li M, Xue X, Wang X. Proteomic analysis reveals oxidative stress-induced activation of Hippo signaling in thiamethoxam-exposed Drosophila. CHEMOSPHERE 2023; 338:139448. [PMID: 37437626 DOI: 10.1016/j.chemosphere.2023.139448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/12/2023] [Accepted: 07/07/2023] [Indexed: 07/14/2023]
Abstract
Thiamethoxam (THIA) is a widely used neonicotinoid insecticide. However, the toxicity and defense mechanisms activated in THIA-exposed insects are unclear. Here, we used isobaric tags for relative and absolute quantitation (iTRAQ) proteomics technology to identify changes in protein expression in THIA-exposed Drosophila. We found that the antioxidant proteins Cyp6a23 and Dys were upregulated, whereas vir-1 was downregulated, which may have been detoxification in response to THIA exposure. Prx5 downregulation promoted the generation of reactive oxygen species. Furthermore, the accumulation of reactive oxygen species led to the induction of antioxidant defenses in THIA-exposed Drosophila, thereby enhancing the levels of oxidative stress markers (e.g., superoxide dismutase, glutathione S-transferase, and glutathione) and reducing catalase expression. Furthermore, the Hippo signaling transcription coactivator Yki was inactivated by THIA. Our results suggesting that Hippo signaling may be necessary to promote insect survival in response to neonicotinoid insecticide toxicity.
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Affiliation(s)
- Xiaoqin Li
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing, 100193, China; Key Laboratory of Plant-Soil Interactions, Ministry of Education, Beijing, 100193, China
| | - Mingquan Li
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing, 100193, China; Key Laboratory of Plant-Soil Interactions, Ministry of Education, Beijing, 100193, China
| | - Xianle Xue
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing, 100193, China
| | - Xing Wang
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing, 100193, China; Key Laboratory of Plant-Soil Interactions, Ministry of Education, Beijing, 100193, China.
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Mirouse V. Evolution and developmental functions of the dystrophin-associated protein complex: beyond the idea of a muscle-specific cell adhesion complex. Front Cell Dev Biol 2023; 11:1182524. [PMID: 37384252 PMCID: PMC10293626 DOI: 10.3389/fcell.2023.1182524] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/30/2023] [Indexed: 06/30/2023] Open
Abstract
The Dystrophin-Associated Protein Complex (DAPC) is a well-defined and evolutionarily conserved complex in animals. DAPC interacts with the F-actin cytoskeleton via dystrophin, and with the extracellular matrix via the membrane protein dystroglycan. Probably for historical reasons that have linked its discovery to muscular dystrophies, DAPC function is often described as limited to muscle integrity maintenance by providing mechanical robustness, which implies strong cell-extracellular matrix adhesion properties. In this review, phylogenetic and functional data from different vertebrate and invertebrate models will be analyzed and compared to explore the molecular and cellular functions of DAPC, with a specific focus on dystrophin. These data reveals that the evolution paths of DAPC and muscle cells are not intrinsically linked and that many features of dystrophin protein domains have not been identified yet. DAPC adhesive properties also are discussed by reviewing the available evidence of common key features of adhesion complexes, such as complex clustering, force transmission, mechanosensitivity and mechanotransduction. Finally, the review highlights DAPC developmental roles in tissue morphogenesis and basement membrane (BM) assembly that may indicate adhesion-independent functions.
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Pan G, Li R, Xu G, Weng S, Yang XL, Yang L, Ye B. Cross-modal modulation gates nociceptive inputs in Drosophila. Curr Biol 2023; 33:1372-1380.e4. [PMID: 36893758 PMCID: PMC10089977 DOI: 10.1016/j.cub.2023.02.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 11/24/2022] [Accepted: 02/09/2023] [Indexed: 03/10/2023]
Abstract
Animals' response to a stimulus in one sensory modality is usually influenced by other modalities.1 One important type of multisensory integration is the cross-modal modulation, in which one sensory modality modulates (typically inhibits) another. Identification of the mechanisms underlying cross-modal modulations is crucial for understanding how sensory inputs shape animals' perception and for understanding sensory processing disorders.2,3,4 However, the synaptic and circuit mechanisms that underlie cross-modal modulation are poorly understood. This is due to the difficulty of separating cross-modal modulation from multisensory integrations in neurons that receive excitatory inputs from two or more sensory modalities5-in which case it is unclear what the modulating or modulated modality is. In this study, we report a unique system for studying cross-modal modulation by taking advantage of the genetic resources in Drosophila. We show that gentle mechanical stimuli inhibit nociceptive responses in Drosophila larvae. Low-threshold mechanosensory neurons inhibit a key second-order neuron in the nociceptive pathway through metabotropic GABA receptors on nociceptor synaptic terminals. Strikingly, this cross-modal inhibition is only effective when nociceptor inputs are weak, thus serving as a gating mechanism for filtering out weak nociceptive inputs. Our findings unveil a novel cross-modal gating mechanism for sensory pathways.
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Affiliation(s)
- Geng Pan
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ruonan Li
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; School of Medicine, Dalian University, Dalian, Liaoning 116622, China
| | - Guozhong Xu
- Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Shijun Weng
- Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Xiong-Li Yang
- Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Limin Yang
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; School of Medicine, Dalian University, Dalian, Liaoning 116622, China.
| | - Bing Ye
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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Ajayi PT, Katti P, Zhang Y, Willingham TB, Sun Y, Bleck CKE, Glancy B. Regulation of the evolutionarily conserved muscle myofibrillar matrix by cell type dependent and independent mechanisms. Nat Commun 2022; 13:2661. [PMID: 35562354 PMCID: PMC9106682 DOI: 10.1038/s41467-022-30401-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 04/29/2022] [Indexed: 12/29/2022] Open
Abstract
Skeletal muscles play a central role in human movement through forces transmitted by contraction of the sarcomere. We recently showed that mammalian sarcomeres are connected through frequent branches forming a singular, mesh-like myofibrillar matrix. However, the extent to which myofibrillar connectivity is evolutionarily conserved as well as mechanisms which regulate the specific architecture of sarcomere branching remain unclear. Here, we demonstrate the presence of a myofibrillar matrix in the tubular, but not indirect flight (IF) muscles within Drosophila melanogaster. Moreover, we find that loss of transcription factor H15 increases sarcomere branching frequency in the tubular jump muscles, and we show that sarcomere branching can be turned on in IF muscles by salm-mediated conversion to tubular muscles. Finally, we demonstrate that neurochondrin misexpression results in myofibrillar connectivity in IF muscles without conversion to tubular muscles. These data indicate an evolutionarily conserved myofibrillar matrix regulated by both cell-type dependent and independent mechanisms.
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Affiliation(s)
- Peter T Ajayi
- Muscle Energetics Laboratory, NHLBI, NIH, Bethesda, MD, 20892, USA
| | - Prasanna Katti
- Muscle Energetics Laboratory, NHLBI, NIH, Bethesda, MD, 20892, USA
| | - Yingfan Zhang
- Muscle Energetics Laboratory, NHLBI, NIH, Bethesda, MD, 20892, USA
| | | | - Ye Sun
- Electron Microscopy Core, NHLBI, NIH, Bethesda, MD, 20892, USA
| | | | - Brian Glancy
- Muscle Energetics Laboratory, NHLBI, NIH, Bethesda, MD, 20892, USA.
- NIAMS, NIH, Bethesda, MD, 20892, USA.
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Wasala NB, Chen SJ, Duan D. Duchenne muscular dystrophy animal models for high-throughput drug discovery and precision medicine. Expert Opin Drug Discov 2020; 15:443-456. [PMID: 32000537 DOI: 10.1080/17460441.2020.1718100] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Introduction: Duchenne muscular dystrophy (DMD) is an X-linked handicapping disease due to the loss of an essential muscle protein dystrophin. Dystrophin-null animals have been extensively used to study disease mechanisms and to develop experimental therapeutics. Despite decades of research, however, treatment options for DMD remain very limited.Areas covered: High-throughput high-content screening and precision medicine offer exciting new opportunities. Here, the authors review animal models that are suitable for these studies.Expert opinion: Nonmammalian models (worm, fruit fly, and zebrafish) are particularly attractive for cost-effective large-scale drug screening. Several promising lead compounds have been discovered using these models. Precision medicine for DMD aims at developing mutation-specific therapies such as exon-skipping and genome editing. To meet these needs, models with patient-like mutations have been established in different species. Models that harbor hotspot mutations are very attractive because the drugs developed in these models can bring mutation-specific therapies to a large population of patients. Humanized hDMD mice carry the entire human dystrophin gene in the mouse genome. Reagents developed in the hDMD mouse-based models are directly translatable to human patients.
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Affiliation(s)
- Nalinda B Wasala
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA
| | - Shi-Jie Chen
- Department of Physics, The University of Missouri, Columbia, MO, USA.,Department of Biochemistry, The University of Missouri, Columbia, MO, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO, USA.,Department of Neurology, School of Medicine, The University of Missouri, Columbia, MO, USA.,Department of Biomedical, Biological & Chemical Engineering, College of Engineering, The University of Missouri, Columbia, MO, USA.,Department of Biomedical Sciences, College of Veterinary Medicine, The University of Missouri, Columbia, MO, USA
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Bar L, Czosnek H, Sobol I, Ghanim M, Hariton Shalev A. Downregulation of dystrophin expression in pupae of the whitefly Bemisia tabaci inhibits the emergence of adults. INSECT MOLECULAR BIOLOGY 2019; 28:662-675. [PMID: 30834620 DOI: 10.1111/imb.12579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The whitefly Bemisia tabaci is a major pest to agriculture. Adults are able to fly for long distances and to colonize staple crops, herbs and ornamentals, and to vector viruses belonging to several important taxonomic groups. During their early development, whiteflies mature from eggs through several nymphal stages (instars I to IV) until adults emerge from pupae. We aim at reducing whitefly populations by inhibiting the emergence of adults from nymphs. Here we targeted dystrophin, a conserved protein essential for the development of the muscle system in humans, other animals and insects. We have exploited the fact that whitefly nymphs developing on tomato leaves feed from the plant phloem via their stylets. Thus, we delivered dystrophin-silencing double-stranded RNA to nymphs developing on leaves of tomato plantlets with their roots bathing in the silencing solution. Downregulation of dystrophin expression occurred mainly in pupae. Dystrophin silencing induced also the downregulation of the dystrophin-associated protein genes actin and tropomyosin, and disrupted F-actin. Most significantly, the treatment inhibited the emergence of adults from pupae, suggesting that targeting dystrophin may help to restrain whitefly populations. This study demonstrates for the first time the important role of dystrophin in the development of a major insect pest to agriculture.
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Affiliation(s)
- L Bar
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - H Czosnek
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - I Sobol
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - M Ghanim
- Department of Entomology, Volcani Center, ARO, Rishon LeZion, Israel
| | - A Hariton Shalev
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Selma-Soriano E, Artero R, Llamusi B. Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles. J Vis Exp 2018. [PMID: 29658931 DOI: 10.3791/56179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight muscles (IFMs) of flies, specifically the dorso-longitudinal muscles (DLM), as the experimental subject to measure the atrophic phenotype brought about by different genetic causes. In this protocol, we describe how to embed fly thorax muscles for semi thin sectioning, how to obtain a good contrast between muscle and the surrounding tissue, and how to process optical microscope images for semiautomatic acquisition of quantifiable data and analysis. We describe three specific applications of the methodological pipeline. First, we show how the method can be applied to quantify muscle degeneration in a myotonic dystrophy fly model; second, measurement of muscle cross-sectional area can help to identify genes that either promote or prevent muscle atrophy and/or muscle degeneration; third, this protocol can be applied to determine whether a candidate compound is able to significantly modify a given atrophic phenotype induced by a disease-causing mutation or by an environmental trigger.
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Affiliation(s)
- Estela Selma-Soriano
- Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), University of Valencia; Incliva Health Research Institute; Joint unit CIPF-Incliva
| | - Rubén Artero
- Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), University of Valencia; Incliva Health Research Institute; Joint unit CIPF-Incliva;
| | - Beatriz Llamusi
- Department of Genetics and Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), University of Valencia; Incliva Health Research Institute; Joint unit CIPF-Incliva
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Potikanond S, Nimlamool W, Noordermeer J, Fradkin LG. Muscular Dystrophy Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:147-172. [PMID: 29951819 DOI: 10.1007/978-981-13-0529-0_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Muscular dystrophy (MD) is a group of muscle weakness disease involving in inherited genetic conditions. MD is caused by mutations or alteration in the genes responsible for the structure and functioning of muscles. There are many different types of MD which have a wide range from mild symptoms to severe disability. Some types involve the muscles used for breathing which eventually affect life expectancy. This chapter provides an overview of the MD types, its gene mutations, and the Drosophila MD models. Specifically, the Duchenne muscular dystrophy (DMD), the most common form of MD, will be thoroughly discussed including Dystrophin genes, their isoforms, possible mechanisms, and signaling pathways of pathogenesis.
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Affiliation(s)
- Saranyapin Potikanond
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
| | - Wutigri Nimlamool
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Jasprien Noordermeer
- Department of Molecular Biology, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Lee G Fradkin
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, USA
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Alison B, Elizabeth G, Steve L, Andrew B, Guy M, Volker S. Animal Models of Duchenne Muscular Dystrophy, with Special Reference to the mdx Mouse. Biocybern Biomed Eng 2012. [DOI: 10.1016/s0208-5216(12)70045-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Marrone AK, Kucherenko MM, Rishko VM, Shcherbata HR. New dystrophin/dystroglycan interactors control neuron behavior in Drosophila eye. BMC Neurosci 2011; 12:93. [PMID: 21943192 PMCID: PMC3217851 DOI: 10.1186/1471-2202-12-93] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 09/26/2011] [Indexed: 01/09/2023] Open
Abstract
Background The Dystrophin Glycoprotein Complex (DGC) is a large multi-component complex that is well known for its function in muscle tissue. When the main components of the DGC, Dystrophin (Dys) and Dystroglycan (Dg) are affected cognitive impairment and mental retardation in addition to muscle degeneration can occur. Previously we performed an array of genetic screens using a Drosophila model for muscular dystrophy in order to find novel DGC interactors aiming to elucidate the signaling role(s) in which the complex is involved. Since the function of the DGC in the brain and nervous system has not been fully defined, we have here continued to analyze the DGC modifiers' function in the developing Drosophila brain and eye. Results Given that disruption of Dys and Dg leads to improper photoreceptor axon projections into the lamina and eye neuron elongation defects during development, we have determined the function of previously screened components and their genetic interaction with the DGC in this tissue. Our study first found that mutations in chif, CG34400, Nrk, Lis1, capt and Cam cause improper axon path-finding and loss of SP2353, Grh, Nrk, capt, CG34400, vimar, Lis1 and Cam cause shortened rhabdomere lengths. We determined that Nrk, mbl, capt and Cam genetically interact with Dys and/or Dg in these processes. It is notable that most of the neuronal DGC interacting components encountered are involved in regulation of actin dynamics. Conclusions Our data indicate possible DGC involvement in the process of cytoskeletal remodeling in neurons. The identification of new components that interact with the DGC not only helps to dissect the mechanism of axon guidance and eye neuron differentiation but also provides a great opportunity for understanding the signaling mechanisms by which the cell surface receptor Dg communicates via Dys with the actin cytoskeleton.
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Affiliation(s)
- April K Marrone
- Max Planck Institute for biophysical chemistry, Research group of Gene Expression and Signaling, Am Fassberg 11, 37077, Goettingen, Germany
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Multi-step usage of in vivo models during rational drug design and discovery. Int J Mol Sci 2011; 12:2262-74. [PMID: 21731440 PMCID: PMC3127116 DOI: 10.3390/ijms12042262] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 03/25/2011] [Accepted: 03/29/2011] [Indexed: 01/04/2023] Open
Abstract
In this article we propose a systematic development method for rational drug design while reviewing paradigms in industry, emerging techniques and technologies in the field. Although the process of drug development today has been accelerated by emergence of computational methodologies, it is a herculean challenge requiring exorbitant resources; and often fails to yield clinically viable results. The current paradigm of target based drug design is often misguided and tends to yield compounds that have poor absorption, distribution, metabolism, and excretion, toxicology (ADMET) properties. Therefore, an in vivo organism based approach allowing for a multidisciplinary inquiry into potent and selective molecules is an excellent place to begin rational drug design. We will review how organisms like the zebrafish and Caenorhabditis elegans can not only be starting points, but can be used at various steps of the drug development process from target identification to pre-clinical trial models. This systems biology based approach paired with the power of computational biology; genetics and developmental biology provide a methodological framework to avoid the pitfalls of traditional target based drug design.
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The RhoGAP crossveinless-c interacts with Dystrophin and is required for synaptic homeostasis at the Drosophila neuromuscular junction. J Neurosci 2011; 31:492-500. [PMID: 21228159 DOI: 10.1523/jneurosci.4732-10.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Duchenne muscular dystrophy is caused by mutations in the Dystrophin gene and is characterized by muscle degeneration and the occurrence of mental deficits in a significant number of patients. Although Dystrophin and its closely related ortholog Utrophin are present at a variety of synapses, little is known about their roles in the nervous system. Previously, we reported that absence of postsynaptic Dystrophin from the Drosophila neuromuscular junction (NMJ) disrupts synaptic homeostasis, resulting in increased stimulus-evoked neurotransmitter release. Here, we show that RhoGAP crossveinless-c (cv-c), a negative regulator of Rho GTPase signaling pathways, genetically interacts with Dystrophin. Electrophysiological characterization of the cv-c-deficient NMJ and the use of presynaptic- and postsynaptic-specific transgenic rescue versus RNA interference reveal that the absence of postsynaptic cv-c results in elevated evoked neurotransmitter release. The cv-c mutant NMJ exhibits an increased number of presynaptic neurotransmitter release sites and higher probability of vesicle release without apparent changes in postsynaptic glutamate receptor numbers or function. Moreover, we find that decreasing expression of the Rho GTPase Cdc42 suppresses the high neurotransmitter release in the cv-c and Dystrophin mutants, suggesting that Cdc42 is a substrate of Cv-c. These results indicate that Dystrophin and the Rho GTPase signaling pathway likely interact at the postsynaptic side of the NMJ to maintain synaptic homeostasis. The absence of this postsynaptic pathway results in presynaptic structural and functional alterations, suggesting that retrograde signaling mechanisms are affected.
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Mosqueira M, Willmann G, Ruohola-Baker H, Khurana TS. Chronic hypoxia impairs muscle function in the Drosophila model of Duchenne's muscular dystrophy (DMD). PLoS One 2010; 5:e13450. [PMID: 20975992 PMCID: PMC2958114 DOI: 10.1371/journal.pone.0013450] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 09/24/2010] [Indexed: 12/14/2022] Open
Abstract
Duchenne's muscular dystrophy (DMD) is a severe progressive myopathy caused by mutations in the DMD gene leading to a deficiency of the dystrophin protein. Due to ongoing muscle necrosis in respiratory muscles late-stage DMD is associated with respiratory insufficiency and chronic hypoxia (CH). To understand the effects of CH on dystrophin-deficient muscle in vivo, we exposed the Drosophila model for DMD (dmDys) to CH during a 16-day ascent to the summit of Mount Denali/McKinley (6194 meters above sea level). Additionally, dmDys and wild type (WT) flies were also exposed to CH in laboratory simulations of high altitude hypoxia. Expression profiling was performed using Affymetrix GeneChips® and validated using qPCR. Hypoxic dmDys differentially expressed 1281 genes, whereas the hypoxic WT flies differentially expressed 56 genes. Interestingly, a number of genes (e.g. heat shock proteins) were discordantly regulated in response to CH between dmDys and WT. We tested the possibility that the disparate molecular responses of dystrophin-deficient tissues to CH could adversely affect muscle by performing functional assays in vivo. Normoxic and CH WT and dmDys flies were challenged with acute hypoxia and time-to-recover determined as well as subjected to climbing tests. Impaired performance was noted for CH-dmDys compared to normoxic dmDys or WT flies (rank order: Normoxic-WT ≈ CH-WT> Normoxic-dmDys> CH-dmDys). These data suggest that dystrophin-deficiency is associated with a disparate, pathological hypoxic stress response(s) and is more sensitive to hypoxia induced muscle dysfunction in vivo. We hypothesize that targeting/correcting the disparate molecular response(s) to hypoxia may offer a novel therapeutic strategy in DMD.
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Affiliation(s)
- Matias Mosqueira
- Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Gabriel Willmann
- Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Hannele Ruohola-Baker
- Department of Biochemistry and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Tejvir S. Khurana
- Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
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16
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Abstract
Current high-throughput screening methods for drug discovery rely on the existence of targets. Moreover, most of the hits generated during screenings turn out to be invalid after further testing in animal models. To by-pass these limitations, efforts are now being made to screen chemical libraries on whole animals. One of the most commonly used animal model in biology is the murine model Mus musculus. However, its cost limit its use in large-scale therapeutic screening. In contrast, the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the fish Danio rerio are gaining momentum as screening tools. These organisms combine genetic amenability, low cost and culture conditions that are compatible with large-scale screens. Their main advantage is to allow high-throughput screening in a whole-animal context. Moreover, their use is not dependent on the prior identification of a target and permits the selection of compounds with an improved safety profile. This review surveys the versatility of these animal models for drug discovery and discuss the options available at this day.
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17
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Nakamura N, Lyalin D, Panin VM. Protein O-mannosylation in animal development and physiology: from human disorders to Drosophila phenotypes. Semin Cell Dev Biol 2010; 21:622-30. [PMID: 20362685 DOI: 10.1016/j.semcdb.2010.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/10/2010] [Accepted: 03/25/2010] [Indexed: 12/13/2022]
Abstract
Protein O-mannosylation has a profound effect on the development and physiology of mammalian organisms. Mutations in genes affecting O-mannosyl glycan biosynthesis result in congenital muscular dystrophies. The main pathological mechanism triggered by O-mannosylation defects is a compromised interaction of cells with the extracellular matrix due to abnormal glycosylation of alpha-dystroglycan. Hypoglycosylation of alpha-dystroglycan impairs its ligand-binding activity and results in muscle degeneration and failure of neuronal migration. Recent experiments revealed the existence of compensatory mechanisms that could ameliorate defects of O-mannosylation. However, these mechanisms remain poorly understood. O-mannosylation and dystroglycan pathway genes show remarkable evolutionary conservation in a wide range of metazoans. Mutations and downregulation of these genes in zebrafish and Drosophila result in muscle defects and degeneration, also causing neurological phenotypes, which suggests that O-mannosylation has similar functions in mammals and lower animals. Thus, future studies in genetically tractable model organisms, such as zebrafish and Drosophila, should help to reveal molecular and genetic mechanisms of mammalian O-mannosylation and its role in the regulation of dystroglycan function.
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Affiliation(s)
- Naosuke Nakamura
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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18
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Abstract
The fruit fly, Drosophila melanogaster, has a long and rich history as an important model organism for biologists. In particular, study of the fruit fly has been essential to much of our fundamental understanding of the development and function of the nervous system. In recent years, studies using fruit flies have provided important insights into the pathogenesis of neurodegenerative and neuromuscular diseases. Fly models of spinal muscular atrophy, spinobulbar muscular atrophy,myotonic dystrophy, dystrophinopathies and other inherited neuromuscular diseases recapitulate many of the key pathologic features of the human disease. The ability to perform genetic screens holds promise for uncovering the molecular mechanisms of disease, and indeed, for identifying novel therapeutic targets. This review will summarize recent progress in developing fly models of neuromuscular diseases and will emphasize the contribution that Drosophila has made to our understanding of these diseases.
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Affiliation(s)
- Thomas E Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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19
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Drosophila as a lipotoxicity model organism — more than a promise? Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:215-21. [DOI: 10.1016/j.bbalip.2009.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 09/04/2009] [Accepted: 09/13/2009] [Indexed: 12/13/2022]
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20
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Pilgram GSK, Potikanond S, Baines RA, Fradkin LG, Noordermeer JN. The roles of the dystrophin-associated glycoprotein complex at the synapse. Mol Neurobiol 2009; 41:1-21. [PMID: 19899002 PMCID: PMC2840664 DOI: 10.1007/s12035-009-8089-5] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Accepted: 10/15/2009] [Indexed: 12/30/2022]
Abstract
Duchenne muscular dystrophy is caused by mutations in the dystrophin gene and is characterized by progressive muscle wasting. A number of Duchenne patients also present with mental retardation. The dystrophin protein is part of the highly conserved dystrophin-associated glycoprotein complex (DGC) which accumulates at the neuromuscular junction (NMJ) and at a variety of synapses in the peripheral and central nervous systems. Many years of research into the roles of the DGC in muscle have revealed its structural function in stabilizing the sarcolemma. In addition, the DGC also acts as a scaffold for various signaling pathways. Here, we discuss recent advances in understanding DGC roles in the nervous system, gained from studies in both vertebrate and invertebrate model systems. From these studies, it has become clear that the DGC is important for the maturation of neurotransmitter receptor complexes and for the regulation of neurotransmitter release at the NMJ and central synapses. Furthermore, roles for the DGC have been established in consolidation of long-term spatial and recognition memory. The challenges ahead include the integration of the behavioral and mechanistic studies and the use of this information to identify therapeutic targets.
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Affiliation(s)
- Gonneke S K Pilgram
- Department of Molecular and Cell Biology, Leiden University Medical Center, The Netherlands
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21
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Draper I, Tabaka ME, Jackson FR, Salomon RN, Kopin AS. The evolutionarily conserved RNA binding protein SMOOTH is essential for maintaining normal muscle function. Fly (Austin) 2009; 3:235-46. [PMID: 19755840 DOI: 10.4161/fly.9517] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Drosophila smooth gene encodes an RNA binding protein that has been well conserved through evolution. To investigate the pleiotropic functions mediated by the smooth gene, we have selected and characterized two sm mutants, which are viable as adults yet display robust phenotypes (including a significant decrease in lifespan). Utilizing these mutants, we have made the novel observation that disruption of the smooth/CG9218 locus leads to age-dependent muscle degeneration, and motor dysfunction. Histological characterization of adult sm mutants revealed marked abnormalities in the major thoracic tubular muscle: the tergal depressor of the trochanter (TDT). Corresponding defects include extensive loss/disruption of striations and nuclei. These pathological changes are recapitulated in flies that express a smooth RNA interference construct (sm RNAi) in the mesoderm. In contrast, targeting sm RNAi constructs to motor neurons does not alter muscle morphology. In addition to examining the TDT phenotype, we explored whether other muscular abnormalities were evident. Utilizing physiological assays developed in the laboratory, we have found that the thoracic muscle defect is preceded by dysmotility of the gastrointestinal tract. SMOOTH thus joins a growing list of hnRNPs that have previously been linked to muscle physiology/pathophysiology. Our findings in Drosophila set the stage for investigating the role of the corresponding mammalian homolog, hnRNP L, in muscle function.
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Affiliation(s)
- Isabelle Draper
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, USA.
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22
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Abstract
The Drosophila melanogaster ovary is a powerful yet simple system with only a few cell types. Cell death in the ovary can be induced in response to multiple developmental and environmental signals. These cell deaths occur at distinct stages of oogenesis and involve unique mechanisms utilizing apoptotic, autophagic and perhaps necrotic processes. In this review, we summarize recent progress characterizing cell death mechanisms in the fly ovary.
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23
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van Gemert AMC, van der Laan AMA, Pilgram GSK, Fradkin LG, Noordermeer JN, Tanke HJ, Jost CR. In vivo monitoring of mRNA movement in Drosophila body wall muscle cells reveals the presence of myofiber domains. PLoS One 2009; 4:e6663. [PMID: 19684860 PMCID: PMC2722729 DOI: 10.1371/journal.pone.0006663] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 07/06/2009] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND In skeletal muscle each muscle cell, commonly called myofiber, is actually a large syncytium containing numerous nuclei. Experiments in fixed myofibers show that mRNAs remain localized around the nuclei in which they are produced. METHODOLOGY/PRINCIPAL FINDINGS In this study we generated transgenic flies that allowed us to investigate the movement of mRNAs in body wall myofibers of living Drosophila embryos. We determined the dynamic properties of GFP-tagged mRNAs using in vivo confocal imaging and photobleaching techniques and found that the GFP-tagged mRNAs are not free to move throughout myofibers. The restricted movement indicated that body wall myofibers consist of three domains. The exchange of mRNAs between the domains is relatively slow, but the GFP-tagged mRNAs move rapidly within these domains. One domain is located at the centre of the cell and is surrounded by nuclei while the other two domains are located at either end of the fiber. To move between these domains mRNAs have to travel past centrally located nuclei. CONCLUSIONS/SIGNIFICANCE These data suggest that the domains made visible in our experiments result from prolonged interactions with as yet undefined structures close to the nuclei that prevent GFP-tagged mRNAs from rapidly moving between the domains. This could be of significant importance for the treatment of myopathies using regenerative cell-based therapies.
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Affiliation(s)
- Alice M. C. van Gemert
- Laboratory of Gene Expression and Imaging, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Annelies M. A. van der Laan
- Laboratory of Gene Expression and Imaging, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Gonneke S. K. Pilgram
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Lee G. Fradkin
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Jasprina N. Noordermeer
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Hans J. Tanke
- Laboratory of Gene Expression and Imaging, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
| | - Carolina R. Jost
- Laboratory of Gene Expression and Imaging, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands
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24
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Kucherenko MM, Pantoja M, Yatsenko AS, Shcherbata HR, Fischer KA, Maksymiv DV, Chernyk YI, Ruohola-Baker H. Genetic modifier screens reveal new components that interact with the Drosophila dystroglycan-dystrophin complex. PLoS One 2008; 3:e2418. [PMID: 18545683 PMCID: PMC2398783 DOI: 10.1371/journal.pone.0002418] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 04/14/2008] [Indexed: 11/24/2022] Open
Abstract
The Dystroglycan-Dystrophin (Dg-Dys) complex has a capacity to transmit information from the extracellular matrix to the cytoskeleton inside the cell. It is proposed that this interaction is under tight regulation; however the signaling/regulatory components of Dg-Dys complex remain elusive. Understanding the regulation of the complex is critical since defects in this complex cause muscular dystrophy in humans. To reveal new regulators of the Dg-Dys complex, we used a model organism Drosophila melanogaster and performed genetic interaction screens to identify modifiers of Dg and Dys mutants in Drosophila wing veins. These mutant screens revealed that the Dg-Dys complex interacts with genes involved in muscle function and components of Notch, TGF-β and EGFR signaling pathways. In addition, components of pathways that are required for cellular and/or axonal migration through cytoskeletal regulation, such as Semaphorin-Plexin, Frazzled-Netrin and Slit-Robo pathways show interactions with Dys and/or Dg. These data suggest that the Dg-Dys complex and the other pathways regulating extracellular information transfer to the cytoskeletal dynamics are more intercalated than previously thought.
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Affiliation(s)
- Mariya M. Kucherenko
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Genetics and Biotechnology, Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Mario Pantoja
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Andriy S. Yatsenko
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Genetics and Biotechnology, Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Halyna R. Shcherbata
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Karin A. Fischer
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Dariya V. Maksymiv
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Genetics and Biotechnology, Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Yaroslava I. Chernyk
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Genetics and Biotechnology, Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Hannele Ruohola-Baker
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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25
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Abstract
The congenital muscular dystrophies present in infancy with muscle weakness and are often associated with mental retardation. Many of these inherited disorders share a common etiology: defective O-glycosylation of alpha-dystroglycan, a component of the dystrophin complex. Protein-O-mannosyl transferase 1 (POMT1) is the first enzyme required for the glycosylation of alpha-dystroglycan, and mutations in the POMT1 gene can lead to both Walker-Warburg syndrome (WWS) and limb girdle muscular dystrophy type 2K (LGMD2K). WWS is associated with severe mental retardation and major structural abnormalities in the brain; however, LGMD2K patients display a more mild retardation with no obvious structural defects in the brain. In a screen for synaptic mutants in Drosophila, we identified mutations in the Drosophila ortholog of POMT1, dPOMT1. Because synaptic defects are a plausible cause of mental retardation, we investigated the molecular and physiological defects associated with loss of dPOMT1 in Drosophila. In dPOMT1 mutants, there is a decrease in the efficacy of synaptic transmission and a change in the subunit composition of the postsynaptic glutamate receptors at the neuromuscular junction. We demonstrate that dPOMT1 is required to glycosylate the Drosophila dystroglycan ortholog Dg in vivo, and that this is the likely cause of these synaptic defects because (1) mutations in Dg lead to similar synaptic defects and (2) genetic interaction studies suggest that dPOMT1 and Dg function in the same pathway. These results are consistent with the model that dPOMT1-dependent glycosylation of Dg is necessary for proper synaptic function and raise the possibility that similar synaptic defects occur in the congenital muscular dystrophies.
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26
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Sparrow J, Hughes SM, Segalat L. Other model organisms for sarcomeric muscle diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 642:192-206. [PMID: 19181102 PMCID: PMC3360967 DOI: 10.1007/978-0-387-84847-1_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Model organisms are vital to our understanding of human muscle biology and disease. The potential of the nematode Caenorhabditis elegans, the fruitfly, Drosophila melanogaster and the zebrafish, Danio rerio, as model genetic organisms for the study of human muscle disease is discussed by examining their muscle biology, muscle genetics and development. The powerful genetic tools available with each organism are outlined. It is concluded that these organisms have already demonstrated potential in facilitating the study of muscle disease and in screening for therapeutic agents.
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Affiliation(s)
- John Sparrow
- Department of Biology, University of York, York, YO1 5DD, UK. Tel: 44-1904-328675; Fax: 44-1904-328825;
| | - Simon M. Hughes
- Randall Division of Cell and Molecular Biophysics and MRC Centre for Developmental Neurobiology, New Hunt’s House, King’s College London, Guy’s Campus, London, SE1 1UL. Tel: 44-20 7848 6445; Fax: 44-7848 6435;
| | - Laurent Segalat
- CNRS-CGMC, Universite Lyon-1 Claude Bernard, Batiment Mendel, 43 bld du 11 Novembre, 69622 Villeurbanne Cedex, France. Tel: 33-4-72-43-29-51; Fax: 33-4-72-43-29-51;
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27
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Christoforou CP, Greer CE, Challoner BR, Charizanos D, Ray RP. The detached locus encodes Drosophila Dystrophin, which acts with other components of the Dystrophin Associated Protein Complex to influence intercellular signalling in developing wing veins. Dev Biol 2007; 313:519-32. [PMID: 18093579 DOI: 10.1016/j.ydbio.2007.09.044] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2007] [Revised: 09/24/2007] [Accepted: 09/24/2007] [Indexed: 11/29/2022]
Abstract
Dystrophin and Dystroglycan are the two central components of the multimeric Dystrophin Associated Protein Complex, or DAPC, that is thought to provide a mechanical link between the extracellular matrix and the actin cytoskeleton, disruption of which leads to muscular dystrophy in humans. We present the characterization of the Drosophila 'crossveinless' mutation detached (det), and show that the gene encodes the fly ortholog of Dystrophin. Our genetic analysis shows that, in flies, Dystrophin is a non-essential gene, and the sole overt morphological defect associated with null mutations in the locus is the variable loss of the posterior crossvein that has been described for alleles of det. Null mutations in Drosophila Dystroglycan (Dg) are similarly viable and exhibit this crossvein defect, indicating that both of the central DAPC components have been co-opted for this atypical function of the complex. In the developing wing, the Drosophila DAPC affects the intercellular signalling pathways involved in vein specification. In det and Dg mutant wings, the early BMP signalling that initiates crossvein specification is not maintained, particularly in the pro-vein territories adjacent to the longitudinal veins, and this results in the production of a crossvein fragment in the intervein between the two longitudinal veins. Genetic interaction studies suggest that the DAPC may exert this effect indirectly by down-regulating Notch signalling in pro-vein territories, leading to enhanced BMP signalling in the intervein by diffusion of BMP ligands from the longitudinal veins.
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Affiliation(s)
- Christina P Christoforou
- Department of Biology and Environmental Science, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
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