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Ellwood RA, Piasecki M, Szewczyk NJ. Caenorhabditis elegans as a Model System for Duchenne Muscular Dystrophy. Int J Mol Sci 2021; 22:ijms22094891. [PMID: 34063069 PMCID: PMC8125261 DOI: 10.3390/ijms22094891] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/26/2021] [Accepted: 04/26/2021] [Indexed: 02/07/2023] Open
Abstract
The nematode worm Caenorhabditis elegans has been used extensively to enhance our understanding of the human neuromuscular disorder Duchenne Muscular Dystrophy (DMD). With new arising clinically relevant models, technologies and treatments, there is a need to reconcile the literature and collate the key findings associated with this model.
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Affiliation(s)
- Rebecca A. Ellwood
- Medical Research Council (MRC) Versus Arthritis, Centre for Musculoskeletal Ageing Research, Royal Derby Hospital, University of Nottingham, Derby DE22 3DT, UK; (R.A.E.); (M.P.)
- National Institute for Health Research, Nottingham Biomedical Research Centre, Derby DE22 3DT, UK
| | - Mathew Piasecki
- Medical Research Council (MRC) Versus Arthritis, Centre for Musculoskeletal Ageing Research, Royal Derby Hospital, University of Nottingham, Derby DE22 3DT, UK; (R.A.E.); (M.P.)
- National Institute for Health Research, Nottingham Biomedical Research Centre, Derby DE22 3DT, UK
| | - Nathaniel J. Szewczyk
- Medical Research Council (MRC) Versus Arthritis, Centre for Musculoskeletal Ageing Research, Royal Derby Hospital, University of Nottingham, Derby DE22 3DT, UK; (R.A.E.); (M.P.)
- National Institute for Health Research, Nottingham Biomedical Research Centre, Derby DE22 3DT, UK
- Ohio Musculoskeletal and Neurologic Institute, Ohio University, Athens, OH 45701, USA
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA
- Correspondence:
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Kawamura K, Maruyama IN. Mutation in histone deacetylase HDA-3 leads to shortened locomotor healthspan in Caenorhabditis elegans. Aging (Albany NY) 2020; 12:23525-23547. [PMID: 33276344 PMCID: PMC7762513 DOI: 10.18632/aging.202296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022]
Abstract
Some genes are essential for survival, while other genes play modulatory roles on health and survival. Genes that play modulatory roles may promote an organism’s survival and health by fine-tuning physiological processes. An unbiased search for genes that alter an organism’s ability to maintain aspects of health may uncover modulators of lifespan and healthspan. From an unbiased screen for Caenorhabditis elegans mutants that show a progressive decline in motility, we aimed to identify genes that play a modulatory role in maintenance of locomotor healthspan. Here we report the involvement of hda-3, encoding a class I histone deacetylase, as a genetic factor that contributes in the maintenance of general health and locomotion in C. elegans. We identified a missense mutation in HDA-3 as the causative mutation in one of the isolated strains that show a progressive decline in maximum velocity and travel distance. From transcriptome analysis, we found a cluster of genes on Chromosome II carrying BATH domains that were downregulated by hda-3. Furthermore, downregulation of individual bath genes leads to significant decline in motility. Our study identifies genetic factors that modulate the maintenance of locomotor healthspan and may reveal potential targets for delaying age-related locomotor decline.
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Affiliation(s)
- Kazuto Kawamura
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
| | - Ichiro N Maruyama
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
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Treinin M, Jin Y. Cholinergic transmission in C. elegans: Functions, diversity, and maturation of ACh-activated ion channels. J Neurochem 2020; 158:1274-1291. [PMID: 32869293 DOI: 10.1111/jnc.15164] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/13/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023]
Abstract
Acetylcholine is an abundant neurotransmitter in all animals. Effects of acetylcholine are excitatory, inhibitory, or modulatory depending on the receptor and cell type. Research using the nematode C. elegans has made ground-breaking contributions to the mechanistic understanding of cholinergic transmission. Powerful genetic screens for behavioral mutants or for responses to pharmacological reagents identified the core cellular machinery for synaptic transmission. Pharmacological reagents that perturb acetylcholine-mediated processes led to the discovery and also uncovered the composition and regulators of acetylcholine-activated channels and receptors. From a combination of electrophysiological and molecular cellular studies, we have gained a profound understanding of cholinergic signaling at the levels of synapses, neural circuits, and animal behaviors. This review will begin with a historical overview, then cover in-depth current knowledge on acetylcholine-activated ionotropic receptors, mechanisms regulating their functional expression and their functions in regulating locomotion.
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Affiliation(s)
- Millet Treinin
- Department of Medical Neurobiology, Hadassah Medical school - Hebrew University, Jerusalem, Israel
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
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4
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Physical exertion exacerbates decline in the musculature of an animal model of Duchenne muscular dystrophy. Proc Natl Acad Sci U S A 2019; 116:3508-3517. [PMID: 30755520 DOI: 10.1073/pnas.1811379116] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a genetic disorder caused by loss of the protein dystrophin. In humans, DMD has early onset, causes developmental delays, muscle necrosis, loss of ambulation, and death. Current animal models have been challenged by their inability to model the early onset and severity of the disease. It remains unresolved whether increased sarcoplasmic calcium observed in dystrophic muscles follows or leads the mechanical insults caused by the muscle's disrupted contractile machinery. This knowledge has important implications for patients, as potential physiotherapeutic treatments may either help or exacerbate symptoms, depending on how dystrophic muscles differ from healthy ones. Recently we showed how burrowing dystrophic (dys-1) C. elegans recapitulate many salient phenotypes of DMD, including loss of mobility and muscle necrosis. Here, we report that dys-1 worms display early pathogenesis, including dysregulated sarcoplasmic calcium and increased lethality. Sarcoplasmic calcium dysregulation in dys-1 worms precedes overt structural phenotypes (e.g., mitochondrial, and contractile machinery damage) and can be mitigated by reducing calmodulin expression. To learn how dystrophic musculature responds to altered physical activity, we cultivated dys-1 animals in environments requiring high intensity or high frequency of muscle exertion during locomotion. We find that several muscular parameters (e.g., size) improve with increased activity. However, longevity in dystrophic animals was negatively associated with muscular exertion, regardless of effort duration. The high degree of phenotypic conservation between dystrophic worms and humans provides a unique opportunity to gain insight into the pathology of the disease as well as the initial assessment of potential treatment strategies.
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Gyenes B, Brown AEX. Deriving Shape-Based Features for C. elegans Locomotion Using Dimensionality Reduction Methods. Front Behav Neurosci 2016; 10:159. [PMID: 27582697 PMCID: PMC4987360 DOI: 10.3389/fnbeh.2016.00159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/03/2016] [Indexed: 11/24/2022] Open
Abstract
High-throughput analysis of animal behavior is increasingly common following the advances of recording technology, leading to large high-dimensional data sets. This dimensionality can sometimes be reduced while still retaining relevant information. In the case of the nematode worm Caenorhabditis elegans, more than 90% of the shape variance can be captured using just four principal components. However, it remains unclear if other methods can achieve a more compact representation or contribute further biological insight to worm locomotion. Here we take a data-driven approach to worm shape analysis using independent component analysis (ICA), non-negative matrix factorization (NMF), a cosine series, and jPCA (a dynamic variant of principal component analysis [PCA]) and confirm that the dimensionality of worm shape space is close to four. Projecting worm shapes onto the bases derived using each method gives interpretable features ranging from head movements to tail oscillation. We use these as a comparison method to find differences between the wild type N2 worms and various mutants. For example, we find that the neuropeptide mutant nlp-1(ok1469) has an exaggerated head movement suggesting a mode of action for the previously described increased turning rate. The different bases provide complementary views of worm behavior and we expect that closer examination of the time series of projected amplitudes will lead to new results in the future.
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Affiliation(s)
- Bertalan Gyenes
- MRC Clinical Sciences CentreLondon, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College LondonLondon, UK; Department of Mathematics, Imperial College LondonLondon, UK
| | - André E X Brown
- MRC Clinical Sciences CentreLondon, UK; Institute of Clinical Sciences, Faculty of Medicine, Imperial College LondonLondon, UK
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Metzler R, Meleshkevitch EA, Fox J, Kim H, Boudko DY. An SLC6 transporter of the novel B(0,)- system aids in absorption and detection of nutrient amino acids in Caenorhabditis elegans. ACTA ACUST UNITED AC 2013; 216:2843-57. [PMID: 23580723 DOI: 10.1242/jeb.081497] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Nutrient amino acid transporters (NATs) of solute carrier family 6 (SLC6) mediate uptake of essential amino acids in mammals and insects. Phylogenomic analysis of the Caenorhabditis elegans (Ce) SLC6 family identifies five genes paralogous to an insect-specific NAT subfamily. Here we cloned and characterized the first representative of the identified nematode-specific transporters, SNF-5. SNF-5 mediates broad spectrum cation-coupled transport of neutral amino acids with submillimolar affinities and stoichiometry of 1 AA:1 Na(+), except for 1 l-Pro:2 Na(+). Unexpectedly, it transports acidic l-Glu(-) and l-Asp(-) (1 AA(-):3 Na(+)), revealing it to be the first member of a new B(0,-) system among characterized SLC6 transporters. This activity correlates with a unique positively charged His(+) 377 in the substrate-binding pocket. snf-5 promoter-driven enhanced green fluorescent protein labels intestinal cells INT1-9 and three pairs of amphid sensory neurons: ASI, ADF and ASK. These cells are intimately involved in control of dauer diapause, development, metabolism and longevity. The snf-5 deletion mutants do not show apparent morphological disorders, but increase dauer formation while reducing dauer maintenance upon starvation. Overall, the present study characterized the first nematode-specific NAT and revealed important structural and functional aspects of this transporter. In addition to the predictable role in alimentary amino acid absorption, our results indicate possible neuronal roles of SNF-5 as an amino acid provider to specific neuronal functions, including sensing of amino acid availability.
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Affiliation(s)
- Ryan Metzler
- The Department of Physiology and Biophysics of the Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, IL 60064, USA
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The atypical calpains: evolutionary analyses and roles in Caenorhabditis elegans cellular degeneration. PLoS Genet 2012; 8:e1002602. [PMID: 22479198 PMCID: PMC3315469 DOI: 10.1371/journal.pgen.1002602] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 02/04/2012] [Indexed: 01/17/2023] Open
Abstract
The calpains are physiologically important Ca2+-activated regulatory proteases, which are divided into typical or atypical sub-families based on constituent domains. Both sub-families are present in mammals, but our understanding of calpain function is based primarily on typical sub-family members. Here, we take advantage of the model organism Caenorhabditis elegans, which expresses only atypical calpains, to extend our knowledge of the phylogenetic evolution and function of calpains. We provide evidence that a typical human calpain protein with a penta EF hand, detected using custom profile hidden Markov models, is conserved in ancient metazoans and a divergent clade. These analyses also provide evidence for the lineage-specific loss of typical calpain genes in C. elegans and Ciona, and they reveal that many calpain-like genes lack an intact catalytic triad. Given the association between the dysregulation of typical calpains and human degenerative pathologies, we explored the phenotypes, expression profiles, and consequences of inappropriate reduction or activation of C. elegans atypical calpains. These studies show that the atypical calpain gene, clp-1, contributes to muscle degeneration and reveal that clp-1 activity is sensitive to genetic manipulation of [Ca2+]i. We show that CLP-1 localizes to sarcomeric sub-structures, but is excluded from dense bodies (Z-disks). We find that the muscle degeneration observed in a C. elegans model of dystrophin-based muscular dystrophy can be suppressed by clp-1 inactivation and that nemadipine-A inhibition of the EGL-19 calcium channel reveals that Ca2+ dysfunction underlies the C. elegans MyoD model of myopathy. Taken together, our analyses highlight the roles of calcium dysregulation and CLP-1 in muscle myopathies and suggest that the atypical calpains could retain conserved roles in myofilament turnover. Calpains are calcium activated non-lysosomal proteases that cleave proteins with exquisite selectivity. Proteins can be activated by calpain cleavage, because they are released from inhibitory constraints, or they can be targeted for further degradation to facilitate their normal physiological turnover or to promote cellular remodelling. Inappropriate calpain activity can lead to degenerative pathologies and cancers. Our understanding of calpain function is based primarily on typical calpains, which carry EF hand motifs that bind Ca2+ or mediate dimerization; however, typical and atypical calpains, which lack EF hand motifs, are both present in mammals. Hence, any therapeutic intervention designed to suppress degenerative conditions, particularly those caused by elevated Ca2+ levels, should also consider the potential involvement of atypical calpains. We have taken advantage of the model organism C. elegans, which only encodes atypical calpain proteins, to gain an understanding of the evolution and activities of these proteins. We show that the CLP-1 atypical calpain is normally expressed in muscle and localizes to sarcomeric sub-structures. We find that CLP-1 contributes to the muscle degeneration observed in a model of Duchenne muscular dystrophy. Our studies also highlight the importance of calcium dysregulation in promoting CLP-1 activity and muscle degeneration.
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Sancar F, Touroutine D, Gao S, Oh HJ, Gendrel M, Bessereau JL, Kim H, Zhen M, Richmond JE. The dystrophin-associated protein complex maintains muscle excitability by regulating Ca(2+)-dependent K(+) (BK) channel localization. J Biol Chem 2011; 286:33501-10. [PMID: 21795674 PMCID: PMC3190934 DOI: 10.1074/jbc.m111.227678] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 07/07/2011] [Indexed: 11/06/2022] Open
Abstract
The dystrophin-associated protein complex (DAPC) consists of several transmembrane and intracellular scaffolding elements that have been implicated in maintaining the structure and morphology of the vertebrate neuromuscular junction (NMJ). Genetic linkage analysis has identified loss-of-function mutations in DAPC genes that give rise to degenerative muscular dystrophies. Although much is known about the involvement of the DAPC in maintaining muscle integrity, less is known about the precise contribution of the DAPC in cell signaling events. To better characterize the functional role of the DAPC at the NMJ, we used electrophysiology, immunohistochemistry, and fluorescent labeling to directly assess cholinergic synaptic transmission, ion channel localization, and muscle excitability in loss-of-function (lf) mutants of Caenorhabditis elegans DAPC homologues. We found that all DAPC mutants consistently display mislocalization of the Ca(2+)-gated K(+) channel, SLO-1, in muscle cells, while ionotropic acetylcholine receptor (AChR) expression and localization at the NMJ remained unaltered. Synaptic cholinergic signaling was also not significantly impacted across DAPC(lf) mutants. Consistent with these findings and the postsynaptic mislocalization of SLO-1, we observed an increase in muscle excitability downstream of cholinergic signaling. Based on our results, we conclude that the DAPC is not involved in regulating AChR architecture at the NMJ, but rather functions to control muscle excitability, in an activity-dependent manner, through the proper localization of SLO-1 channels.
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Affiliation(s)
- Feyza Sancar
- From the Department of Biological Sciences, University of Illinois-Chicago, Chicago, Illinois 60607
| | - Denis Touroutine
- the Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Shangbang Gao
- the Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Hyun J. Oh
- the Department of Cell Biology and Anatomy, Rosalind Franklin University of Science and Medicine, North Chicago, Illinois 60064
| | - Marie Gendrel
- the Biology Department, Institut de Biologie de l'Ecole Normale Superieure, F-75005 Paris, France
| | - Jean-Louis Bessereau
- the Biology Department, Institut de Biologie de l'Ecole Normale Superieure, F-75005 Paris, France
- the Inserm, Unite 1024, F-75005 Paris, France, and
- the Centre National de la Recherche Scientifique, Unit e Mixte de Recherche 8197, F-75005 Paris, France
| | - Hongkyun Kim
- the Department of Cell Biology and Anatomy, Rosalind Franklin University of Science and Medicine, North Chicago, Illinois 60064
| | - Mei Zhen
- the Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Janet E. Richmond
- From the Department of Biological Sciences, University of Illinois-Chicago, Chicago, Illinois 60607
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Minullina RT, Osin YN, Ishmuchametova DG, Fakhrullin RF. Interfacing multicellular organisms with polyelectrolyte shells and nanoparticles: a Caenorhabtidis elegans study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7708-7713. [PMID: 21591632 DOI: 10.1021/la2006869] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report the surface modification of microscopic live multicellular nematodes Caenorhabtidis elegans with polyelectrolyte multilayers (pure and doped with 20 nm gold nanoparticles) and the direct magnetic functionalization of nematodes with biocompatible magnetic nanoparticles. Magnetically functionalized "ironoxideclad" nematodes can be effectively separated and moved using an external magnetic field. The surface-functionalized nematodes preserve their viability and reproduction.
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Affiliation(s)
- Renata T Minullina
- Biomaterials and Nanomaterials Group, Department of Biochemistry, Kazan (Idel buye\Volga region) Federal University, Kreml uramı 18, Kazan, Republic of Tatarstan, RF 420008
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Abstract
The dystrophin protein complex, an important regulator of muscle membrane integrity, also maintains neural organization through interactions with the L1CAM family member SAX-7. The dystrophin protein complex (DPC), composed of dystrophin and associated proteins, is essential for maintaining muscle membrane integrity. The link between mutations in dystrophin and the devastating muscle failure of Duchenne’s muscular dystrophy (DMD) has been well established. Less well appreciated are the accompanying cognitive impairment and neuropsychiatric disorders also presented in many DMD patients, which suggest a wider role for dystrophin in membrane–cytoskeleton function. This study provides genetic evidence of a novel role for DYS-1/dystrophin in maintaining neural organization in Caenorhabditis elegans. This neuronal function is distinct from the established role of DYS-1/dystrophin in maintaining muscle integrity and regulating locomotion. SAX-7, an L1 cell adhesion molecule (CAM) homologue, and STN-2/γ-syntrophin also function to maintain neural integrity in C. elegans. This study provides biochemical data that show that SAX-7 associates with DYS-1 in an STN-2/γ-syntrophin–dependent manner. These results reveal a recruitment of L1CAMs to the DPC to ensure neural integrity is maintained.
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Affiliation(s)
- Shan Zhou
- Department of Genetics, Cell Biology, and Development, Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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Abstract
With unique genetic and cell biological strengths, C. elegans has emerged as a powerful model system for studying many biological processes. These processes are typically regulated by complex genetic networks consisting of genes. Identifying those genes and organizing them into genetic pathways are two major steps toward understanding the mechanisms that regulate biological events. Forward genetic screens with various designs are a traditional approach for identifying candidate genes. The completion of the genome sequencing in C. elegans and the advent of high-throughput experimental techniques have led to the development of two additional powerful approaches: functional genomics and systems biology. Genes that are discovered by these approaches can be ordered into interacting pathways through a variety of strategies, involving genetics, cell biology, biochemistry, and functional genomics, to gain a more complete understanding of how gene regulatory networks control a particular biological process. The aim of this review is to provide an overview of the approaches available to identify and construct the genetic pathways using C. elegans.
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Affiliation(s)
- Zheng Wang
- Dept. of Biology, Duke University, Durham NC
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Markaki M, Tavernarakis N. Modeling human diseases in Caenorhabditis elegans. Biotechnol J 2010; 5:1261-76. [PMID: 21154667 DOI: 10.1002/biot.201000183] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 10/22/2010] [Accepted: 10/25/2010] [Indexed: 01/15/2023]
Abstract
Genes linked to human diseases often function in evolutionarily conserved pathways, which can be readily dissected in simple model organisms. Because of its short lifespan and well-known biology, coupled with a completely sequenced genome that shares extensive homology with that of mammals, Caenorhabditis elegans is one of the most versatile and powerful model organisms. Research in C. elegans has been instrumental for the elucidation of molecular pathways implicated in many human diseases. In this review, we introduce C. elegans as a model organism for biomedical research and we survey recent relevant findings that shed light on the basic molecular determinants of human disease pathophysiology. The nematode holds promise of providing clear leads towards the identification of potential targets for the development of new therapeutic interventions against human diseases.
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Affiliation(s)
- Maria Markaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, N. Plastira 100, Vassilika Vouton, Heraklion, Crete, Greece
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Abraham LS, Oh HJ, Sancar F, Richmond JE, Kim H. An alpha-catulin homologue controls neuromuscular function through localization of the dystrophin complex and BK channels in Caenorhabditis elegans. PLoS Genet 2010; 6. [PMID: 20865173 PMCID: PMC2928805 DOI: 10.1371/journal.pgen.1001077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 07/21/2010] [Indexed: 11/25/2022] Open
Abstract
The large conductance, voltage- and calcium-dependent potassium (BK) channel serves as a major negative feedback regulator of calcium-mediated physiological processes and has been implicated in muscle dysfunction and neurological disorders. In addition to membrane depolarization, activation of the BK channel requires a rise in cytosolic calcium. Localization of the BK channel near calcium channels is therefore critical for its function. In a genetic screen designed to isolate novel regulators of the Caenorhabditis elegans BK channel, SLO-1, we identified ctn-1, which encodes an α-catulin homologue with homology to the cytoskeletal proteins α-catenin and vinculin. ctn-1 mutants resemble slo-1 loss-of-function mutants, as well as mutants with a compromised dystrophin complex. We determined that CTN-1 uses two distinct mechanisms to localize SLO-1 in muscles and neurons. In muscles, CTN-1 utilizes the dystrophin complex to localize SLO-1 channels near L-type calcium channels. In neurons, CTN-1 is involved in localizing SLO-1 to a specific domain independent of the dystrophin complex. Our results demonstrate that CTN-1 ensures the localization of SLO-1 within calcium nanodomains, thereby playing a crucial role in muscles and neurons. Calcium ions are essential for many physiological processes, including neurosecretion and neuronal and muscle excitation. Paradoxically, abnormal accumulation of calcium ions is associated with cell death and has been documented as an early event in muscle and neural degenerative diseases. One mechanism to avoid detrimental calcium accumulation is to link the calcium increase with activation of calcium-dependent potassium ion channels, thereby reducing cell excitability and preventing further calcium influx. This negative feedback requires these potassium channels to be localized in close proximity to sites of calcium entry. In a Caenorhabditis elegans genetic screen, we identified α-catulin, known as a cytoskeletal regulatory protein in mammals, important for the localization of calcium-dependent potassium channels in both muscles and neurons. In muscle, α-catulin controls the localization of the dystrophin complex, a multimeric protein complex implicated in muscular dystrophy. The dystrophin complex in turn tethers the calcium-dependent potassium channels near calcium channels. In neurons, the α-catulin-mediated localization of the potassium channels is independent of the dystrophin complex. Lack of α-catulin results in mislocalization of the potassium channels, and in turn causes defects in neuromuscular function. Our results support the idea that cytoskeletal proteins function as anchor molecules that localize ion channels to specific cellular domains.
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Affiliation(s)
- Linu S. Abraham
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Hyun J. Oh
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
| | - Feyza Sancar
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Janet E. Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Hongkyun Kim
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America
- * E-mail:
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14
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Rana OR, Schauerte P, Kluttig R, Schröder JW, Koenen RR, Weber C, Nolte KW, Weis J, Hoffmann R, Marx N, Saygili E. Acetylcholine as an age-dependent non-neuronal source in the heart. Auton Neurosci 2010; 156:82-9. [PMID: 20510655 DOI: 10.1016/j.autneu.2010.04.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/28/2010] [Accepted: 04/29/2010] [Indexed: 10/19/2022]
Abstract
In the heart, acetylcholine (ACh) slows pacemaker activity, depresses contractility and slows conduction in the atrioventricular node. Beside these cardiovascular effects, ACh has also been associated with an anti-inflammatory and anti-apoptotic pathway. There is no evidence for ACh synthesis and excretion in other cell types than neuronal cells in the heart. Therefore, this study investigates whether cardiomyocytes are able to synthesize, transport and excrete ACh in the heart. We chose a rat model of different aged rats (neonatal, 6-8 week = young, 20-24 month = old). By real-time PCR, Western blot and immunofluorescence experiments we could demonstrate that adult, but not neonatal cardiomyocytes, express the choline acetyltransferase (ChAT). The expression level of ChAT is down-regulated in old cardiomyocytes. Furthermore, we found that young and old cardiomyocytes express the ACh transport proteins choline transporter-1 (CHT-1) and the vesicular acetylcholine transporter (VAChT). The amount of ACh excretion detected by high performance liquid chromatography (HPLC) is significantly down-regulated in old cardiomyocytes. Bromo-acetylcholine (BrACh), a specific ChAT inhibitor, significantly decreased ACh concentrations in cardiomyocyte supernatants demonstrating that ChAT is the main ACh synthesizing enzyme in cardiomyocytes. In conclusion, we could demonstrate that adult, but not neonatal, cardiomyocytes are able to synthesize, transport and excrete ACh in the rat heart. The expression level of ChAT and the ACh excretion amount are significantly down-regulated in old cardiomyocytes. This finding may provide new physiological/pathological aspects in the communication between cardiomyocytes and other cell types in the myocardium, e.g. fibrocytes, neurocytes or endothelial cells.
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Affiliation(s)
- Obaida R Rana
- Department of Cardiology, RWTH Aachen University, Aachen, 52074, Germany.
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15
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Lee AY, Perreault R, Harel S, Boulier EL, Suderman M, Hallett M, Jenna S. Searching for signaling balance through the identification of genetic interactors of the Rab guanine-nucleotide dissociation inhibitor gdi-1. PLoS One 2010; 5:e10624. [PMID: 20498707 PMCID: PMC2869356 DOI: 10.1371/journal.pone.0010624] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 03/22/2010] [Indexed: 12/27/2022] Open
Abstract
Background The symptoms of numerous diseases result from genetic mutations that disrupt the homeostasis maintained by the appropriate integration of signaling gene activities. The relationships between signaling genes suggest avenues through which homeostasis can be restored and disease symptoms subsequently reduced. Specifically, disease symptoms caused by loss-of-function mutations in a particular gene may be reduced by concomitant perturbations in genes with antagonistic activities. Methodology/Principal Findings Here we use network-neighborhood analyses to predict genetic interactions in Caenorhabditis elegans towards mapping antagonisms and synergisms between genes in an animal model. Most of the predicted interactions are novel, and the experimental validation establishes that our approach provides a gain in accuracy compared to previous efforts. In particular, we identified genetic interactors of gdi-1, the orthologue of GDI1, a gene associated with mental retardation in human. Interestingly, some gdi-1 interactors have human orthologues with known neurological functions, and upon validation of the interactions in mammalian systems, these orthologues would be potential therapeutic targets for GDI1-associated neurological disorders. We also observed the conservation of a gdi-1 interaction between different cellular systems in C. elegans, suggesting the involvement of GDI1 in human muscle degeneration. Conclusions/Significance We developed a novel predictor of genetic interactions that may have the ability to significantly streamline the identification of therapeutic targets for monogenic disorders involving genes conserved between human and C. elegans.
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Affiliation(s)
- Anna Y. Lee
- McGill Centre for Bioinformatics, McGill University, Montréal, Québec, Canada
- School of Computer Science, McGill University, Montréal, Québec, Canada
| | - Richard Perreault
- Department of Chemistry, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Sharon Harel
- Department of Chemistry, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Elodie L. Boulier
- Department of Chemistry, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Matthew Suderman
- McGill Centre for Bioinformatics, McGill University, Montréal, Québec, Canada
| | - Michael Hallett
- McGill Centre for Bioinformatics, McGill University, Montréal, Québec, Canada
- School of Computer Science, McGill University, Montréal, Québec, Canada
- Rosalind and Morris Goodman Cancer Centre, McGill University, Montréal, Québec, Canada
| | - Sarah Jenna
- Department of Chemistry, Université du Québec à Montréal, Montréal, Québec, Canada
- Pharmaqam, Université du Québec à Montréal, Montréal, Québec, Canada
- Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
- * E-mail:
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16
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Isikman SO, Sencan I, Mudanyali O, Bishara W, Oztoprak C, Ozcan A. Color and monochrome lensless on-chip imaging of Caenorhabditis elegans over a wide field-of-view. LAB ON A CHIP 2010; 10:1109-12. [PMID: 20390127 PMCID: PMC2869489 DOI: 10.1039/c001200a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We demonstrate color and monochrome on-chip imaging of Caenorhabditis elegans samples over a wide field-of-view using incoherent lensless in-line holography. Digital reconstruction of the recorded lensless holograms rapidly creates the C. elegans images within <1 s over a field-of-view of >24 mm2. By digitally combining the reconstructed images at three different wavelengths (red, green and blue), color images of dyed samples are also acquired. This wide field-of-view and compact on-chip imaging modality also permits straightforward integration with microfluidic systems.
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Affiliation(s)
- Serhan O Isikman
- Electrical Engineering Department, University of California, Los Angeles, CA 90095, USA
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17
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Abstract
AbstractThe nematode Caenorhabditis elegans is a genetic model organism and the only animal with a complete nervous system wiring diagram. With only 302 neurons and 95 striated muscle cells, a rich array of mutants with defective locomotion and the facility for individual targeted gene knockdown by RNA interference, it lends itself to the exploration of gene function at nerve muscle junctions. With approximately 60% of human disease genes having a C. elegans homologue, there is growing interest in the deployment of lowcost, high-throughput, drug screens of nematode transgenic and mutant strains mimicking aspects of the pathology of devastating human neuromuscular disorders. Here we explore the contributions already made by C. elegans to our understanding of muscular dystrophies (Duchenne and Becker), spinal muscular atrophy, amyotrophic lateral sclerosis, Friedreich’s ataxia, inclusion body myositis and the prospects for contributions to other neuromuscular disorders. A bottleneck to low-cost, in vivo, large-scale chemical library screening for new candidate therapies has been rapid, automated, behavioural phenotyping. Recent progress in quantifying simple swimming (thrashing) movements is making such screening possible and is expediting the translation of drug candidates towards the clinic.
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18
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Kim H, Pierce-Shimomura JT, Oh HJ, Johnson BE, Goodman MB, McIntire SL. The dystrophin complex controls bk channel localization and muscle activity in Caenorhabditis elegans. PLoS Genet 2009; 5:e1000780. [PMID: 20019812 PMCID: PMC2788698 DOI: 10.1371/journal.pgen.1000780] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 11/19/2009] [Indexed: 01/05/2023] Open
Abstract
Genetic defects in the dystrophin-associated protein complex (DAPC) are responsible for a variety of pathological conditions including muscular dystrophy, cardiomyopathy, and vasospasm. Conserved DAPC components from humans to Caenorhabditis elegans suggest a similar molecular function. C. elegans DAPC mutants exhibit a unique locomotory deficit resulting from prolonged muscle excitation and contraction. Here we show that the C. elegans DAPC is essential for proper localization of SLO-1, the large conductance, voltage-, and calcium-dependent potassium (BK) channel, which conducts a major outward rectifying current in muscle under the normal physiological condition. Through analysis of mutants with the same phenotype as the DAPC mutants, we identified the novel islo-1 gene that encodes a protein with two predicted transmembrane domains. We demonstrate that ISLO-1 acts as a novel adapter molecule that links the DAPC to SLO-1 in muscle. We show that a defect in either the DAPC or ISLO-1 disrupts normal SLO-1 localization in muscle. Consistent with observations that SLO-1 requires a high calcium concentration for full activation, we find that SLO-1 is localized near L-type calcium channels in muscle, thereby providing a mechanism coupling calcium influx with the outward rectifying current. Our results indicate that the DAPC modulates muscle excitability by localizing the SLO-1 channel to calcium-rich regions of C. elegans muscle. Dystrophin is a long rod-shaped protein that forms a complex with several membrane and cytoplasmic proteins in muscle. Genetic defects in components of this dystrophin complex are responsible for many forms of muscular dystrophy, including Duchenne muscular dystrophy. C. elegans possesses the dystrophin complex and mutations in its components cause muscular defects, indicating that the dystrophin complex has an evolutionary conserved role in muscle. Accumulating evidence in mammals indicates that dystrophic muscle exhibits an abnormal calcium homeostasis. It is not clear how defects in the dystrophin complex are linked to calcium homeostasis, however. In a C. elegans genetic study we found that a novel adaptor protein links the dystrophin complex to a calcium-sensitive potassium channel that mediates muscle inactivation. We further demonstrated that both the dystrophin complex and the adaptor protein localize the potassium channel in a close proximity to a muscle-activating calcium channel. This arrangement ensures that calcium increases accompanied by muscle activation are coupled to muscle inactivation. Defects in the dystrophin complex or the adaptor disrupt the localization of the potassium channel, thereby resulting in prolonged muscle activation and calcium ion increases. Our study provides a mechanism by which the dystrophin complex regulates cellular signaling and muscle excitability.
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Affiliation(s)
- Hongkyun Kim
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, Illinois, United States of America
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
- * E-mail: (HK); (SLM)
| | - Jonathan T. Pierce-Shimomura
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
| | - Hyun J. Oh
- Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, Illinois, United States of America
| | - Brandon E. Johnson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Miriam B. Goodman
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Steven L. McIntire
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, Emeryville, California, United States of America
- * E-mail: (HK); (SLM)
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19
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Hueston JL, Suprenant KA. Loss of dystrophin and the microtubule-binding protein ELP-1 causes progressive paralysis and death of adult C. elegans. Dev Dyn 2009; 238:1878-86. [PMID: 19582871 DOI: 10.1002/dvdy.22007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
EMAP-like proteins (ELPs) are conserved microtubule-binding proteins that function during cell division and in the behavior of post-mitotic cells. In Caenorhabditis elegans, ELP-1 is broadly expressed in many cells and tissues including the touch receptor neurons and body wall muscle. Within muscle, ELP-1 is associated with a microtubule network that is closely opposed to the integrin-based adhesion sites called dense bodies. To examine ELP-1 function, we utilized an elp-1 RNA interference assay and screened for synthetic interactions with mutated adhesion site proteins. We reveal a synthetic lethal relationship between ELP-1 and the dystrophin-like protein, DYS-1. Reduction of ELP-1 in a dystrophin [dys-1(cx18)] mutant results in adult animals with motility defects, splayed and hypercontracted muscle with altered cholinergic signaling. Worms fill with vesicles, become flaccid, and die. We conclude that ELP-1 is a genetic modifier of a C. elegans model of muscular dystrophy.
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Affiliation(s)
- Jennifer L Hueston
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045-7534, USA
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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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Augustin H, Partridge L. Invertebrate models of age-related muscle degeneration. Biochim Biophys Acta Gen Subj 2009; 1790:1084-94. [PMID: 19563864 DOI: 10.1016/j.bbagen.2009.06.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 06/12/2009] [Accepted: 06/20/2009] [Indexed: 12/26/2022]
Abstract
Functional and structural deterioration of muscles is an inevitable consequence of ageing in a wide variety of animal species. What underlies these changes is a complex network of interactions between the muscle-intrinsic and muscle-extrinsic factors, making it very difficult to distinguish between the cause and the consequence. Many of the genes, structures, and processes implicated in mammalian skeletal muscle ageing are preserved in invertebrate species Drosophila melanogaster and Caenorhabditis elegans. The absence in these organisms of mechanisms that promote muscle regeneration, and substantially different hormonal environment, warrant caution when extrapolating experimental data from studies conducted in invertebrates to mammalian species. The simplicity and accessibility of these models, however, offer ample opportunities for studying age-related myopathologies as well as investigating drugs and therapies to alleviate them.
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Affiliation(s)
- Hrvoje Augustin
- Institute of Healthy Ageing and GEE, University College London, London WC1E 6BT, UK
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22
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Ghedini PC, Viel TA, Honda L, Avellar MCW, Godinho RO, Lima-Landman MTR, Lapa AJ, Souccar C. Increased expression of acetylcholine receptors in the diaphragm muscle of MDX mice. Muscle Nerve 2009; 38:1585-94. [PMID: 19016551 DOI: 10.1002/mus.21183] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The absence of dystrophin in Duchenne muscular dystrophy (DMD) and in the mutant mdx mouse causes muscle degeneration and disruption of the neuromuscular junction. Based on evidence from the denervation-like properties of these muscles, we assessed the ligand-binding constants of nicotinic acetylcholine receptors (nAChRs) and the mRNA expression of individual subunits in membrane preparations of diaphragm muscles from adult (4-month-old) and aged (20-month-old) control and mdx mice. The concentration of nAChRs as determined by the maximal specific [(125)I]-alpha-bungarotoxin binding (Bmax) in the muscle membranes did not change with aging in both animal strains. When compared to age-matched control groups, the Bmax in mdx muscles was increased by 65% in adults, and by 103% in aged mice with no alteration of toxin affinity for nAChRs. Reverse-transcription polymerase chain reaction assays showed that mRNA transcripts for the nAChR alpha1, gamma, alpha7, and beta2, but not the epsilon subunits, were more abundant in mdx than in control muscles. The results indicate increased expression of extrajunctional nAChRs in the mdx diaphragm and reflect impairment of nAChR regulation in dystrophin-deficient muscles. These observations may be related to the resistance to nondepolarizing muscle relaxants and the high sensitivity to depolarizing agents reported in DMD patients.
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Affiliation(s)
- Paulo C Ghedini
- Department of Pharmacology, Natural Products Section, Universidade Federal de São Paulo, 04044-020, Rua Três de Maio 100, São Paulo, SP, Brazil
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23
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The dystrophin Dp186 isoform regulates neurotransmitter release at a central synapse in Drosophila. J Neurosci 2008; 28:5105-14. [PMID: 18463264 DOI: 10.1523/jneurosci.4950-07.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Dystrophin protein is encoded by a gene that, when mutated in humans, can cause Duchenne muscular dystrophy, a disease characterized by progressive muscle wasting. A number of Duchenne patients also exhibit poorly understood mental retardation, likely associated with loss of a brain-specific isoform. Furthermore, although Dystrophin isoforms and the related Utrophin protein have long been known to localize at synapses, their functions remain essentially unknown. In Drosophila, we find that the CNS-specific Dp186 isoform localizes to the embryonic and larval neuropiles, regions rich in synaptic contacts. In the absence of Dp186, evoked but not spontaneous presynaptic release is significantly enhanced. Increased presynaptic release can be fully rescued to wild-type levels by expression of a Dp186 transgene in the postsynaptic motoneuron, indicating that Dp186 likely regulates a retrograde signaling pathway. Potentiation of synaptic currents in the mutant also occurs when cholinergic transmission is inhibited or in the absence of Glass Bottom Boat (Gbb) or Wishful Thinking (Wit), a TGF-beta ligand and receptor, respectively, both previously implicated in synaptic retrograde signaling. These results are consistent with the possibility that Dp186 modulates other non-Gbb/Wit-dependent retrograde signaling pathways required to maintain normal synaptic physiology.
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24
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Ervasti JM, Sonnemann KJ. Biology of the striated muscle dystrophin-glycoprotein complex. INTERNATIONAL REVIEW OF CYTOLOGY 2008; 265:191-225. [PMID: 18275889 DOI: 10.1016/s0074-7696(07)65005-0] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Since its first description in 1990, the dystrophin-glycoprotein complex has emerged as a critical nexus for human muscular dystrophies arising from defects in a variety of distinct genes. Studies in mammals widely support a primary role for the dystrophin-glycoprotein complex in mechanical stabilization of the plasma membrane in striated muscle and provide hints for secondary functions in organizing molecules involved in cellular signaling. Studies in model organisms confirm the importance of the dystrophin-glycoprotein complex for muscle cell viability and have provided new leads toward a full understanding of its secondary roles in muscle biology.
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Affiliation(s)
- James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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25
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Lecroisey C, Martin E, Mariol MC, Granger L, Schwab Y, Labouesse M, Ségalat L, Gieseler K. DYC-1, a protein functionally linked to dystrophin in Caenorhabditis elegans is associated with the dense body, where it interacts with the muscle LIM domain protein ZYX-1. Mol Biol Cell 2007; 19:785-96. [PMID: 18094057 DOI: 10.1091/mbc.e07-05-0497] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In Caenorhabditis elegans, mutations of the dystrophin homologue, dys-1, produce a peculiar behavioral phenotype (hyperactivity and a tendency to hypercontract). In a sensitized genetic background, dys-1 mutations also lead to muscle necrosis. The dyc-1 gene was previously identified in a genetic screen because its mutation leads to the same phenotype as dys-1, suggesting that the two genes are functionally linked. Here, we report the detailed characterization of the dyc-1 gene. dyc-1 encodes two isoforms, which are expressed in neurons and muscles. Isoform-specific RNAi experiments show that the absence of the muscle isoform, and not that of the neuronal isoform, is responsible for the dyc-1 mutant phenotype. In the sarcomere, the DYC-1 protein is localized at the edges of the dense body, the nematode muscle adhesion structure where actin filaments are anchored and linked to the sarcolemma. In yeast two-hybrid assays, DYC-1 interacts with ZYX-1, the homologue of the vertebrate focal adhesion LIM domain protein zyxin. ZYX-1 localizes at dense bodies and M-lines as well as in the nucleus of C. elegans striated muscles. The DYC-1 protein possesses a highly conserved 19 amino acid sequence, which is involved in the interaction with ZYX-1 and which is sufficient for addressing DYC-1 to the dense body. Altogether our findings indicate that DYC-1 may be involved in dense body function and stability. This, taken together with the functional link between the C. elegans DYC-1 and DYS-1 proteins, furthermore suggests a requirement of dystrophin function at this structure. As the dense body shares functional similarity with both the vertebrate Z-disk and the costamere, we therefore postulate that disruption of muscle cell adhesion structures might be the primary event of muscle degeneration occurring in the absence of dystrophin, in C. elegans as well as vertebrates.
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Affiliation(s)
- Claire Lecroisey
- Université Lyon 1, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5534, Centre de Génétique Moléculaire et Cellulaire, Bâtiment Mendel, Villeurbanne, F-69622, France
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26
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van der Plas MC, Pilgram GSK, de Jong AWM, Bansraj MRKS, Fradkin LG, Noordermeer JN. Drosophila Dystrophin is required for integrity of the musculature. Mech Dev 2007; 124:617-30. [PMID: 17543506 DOI: 10.1016/j.mod.2007.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 03/17/2007] [Accepted: 04/16/2007] [Indexed: 11/21/2022]
Abstract
Duchenne muscular dystrophy is caused by mutations in the dystrophin gene and is characterized by progressive muscle wasting. The highly conserved dystrophin gene encodes a number of protein isoforms. The Dystrophin protein is part of a large protein assembly, the Dystrophin glycoprotein complex, which stabilizes the muscle membrane during contraction and acts as a scaffold for signaling molecules. How the absence of Dystrophin results in the onset of muscular dystrophy remains unclear. Here, we have used transgenic RNA interference to examine the roles of the Drosophila Dystrophin isoforms in muscle. We previously reported that one of the Drosophila Dystrophin orthologs, the DLP2 isoform, is not required to maintain muscle integrity, but plays a role in neuromuscular homeostasis by regulating neurotransmitter release. In this report, we show that reduction of all Dystrophin isoform expression levels in the musculature does not apparently affect myogenesis or muscle attachment, but results in progressive muscle degeneration in larvae and adult flies. We find that a recently identified Dystrophin isoform, Dp117, is expressed in the musculature and is required for muscle integrity. Muscle fibers with reduced levels of Dp117 display disorganized actin-myosin filaments and the cellular hallmarks of necrosis. Our results indicate the existence of at least two possibly separate roles of dystrophin in muscle, maintaining synaptic homeostasis and preserving the structural stability of the muscle.
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Affiliation(s)
- Mariska C van der Plas
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Einthovenweg 20, PO Box 9600, 2300 RC Leiden, The Netherlands
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27
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Artal-Sanz M, de Jong L, Tavernarakis N. Caenorhabditis elegans: a versatile platform for drug discovery. Biotechnol J 2007; 1:1405-18. [PMID: 17109493 DOI: 10.1002/biot.200600176] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Drug discovery and drug target identification are two intimately linked facets of intervention strategies aimed at effectively combating pathological conditions in humans. Simple model organisms provide attractive platforms for devising and streamlining efficient drug discovery and drug target identification methodologies. The nematode worm Caenorhabditis elegans has emerged as a particularly convenient and versatile tool that can be exploited to achieve these goals. Although C. elegans is a relatively modern addition to the arsenal of model organisms, its biology has already been investigated to an exceptional level. This, coupled with effortless handling and a notable low cost of cultivation and maintenance, allows seamless implementation of high-throughput drug screening approaches as well as in-depth genetic and biochemical studies of the molecular pathways targeted by specific drugs. In this review, we introduce C. elegans as a model organism with significant advantages toward the identification of molecular drug targets. In addition, we discuss the value of the worm in the development of drug screening and drug evaluation protocols. The unique features of C. elegans, which greatly facilitate drug studies, hold promise for both deciphering disease pathogenesis and formulating educated and effective therapeutic interventions.
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Affiliation(s)
- Marta Artal-Sanz
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Hellas, Crete, Greece
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28
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Shcherbata HR, Yatsenko AS, Patterson L, Sood VD, Nudel U, Yaffe D, Baker D, Ruohola-Baker H. Dissecting muscle and neuronal disorders in a Drosophila model of muscular dystrophy. EMBO J 2007; 26:481-93. [PMID: 17215867 PMCID: PMC1783456 DOI: 10.1038/sj.emboj.7601503] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Accepted: 11/22/2006] [Indexed: 11/08/2022] Open
Abstract
Perturbation in the Dystroglycan (Dg)-Dystrophin (Dys) complex results in muscular dystrophies and brain abnormalities in human. Here we report that Drosophila is an excellent genetically tractable model to study muscular dystrophies and neuronal abnormalities caused by defects in this complex. Using a fluorescence polarization assay, we show a high conservation in Dg-Dys interaction between human and Drosophila. Genetic and RNAi-induced perturbations of Dg and Dys in Drosophila cause cell polarity and muscular dystrophy phenotypes: decreased mobility, age-dependent muscle degeneration and defective photoreceptor path-finding. Dg and Dys are required in targeting glial cells and neurons for correct neuronal migration. Importantly, we now report that Dg interacts with insulin receptor and Nck/Dock SH2/SH3-adaptor molecule in photoreceptor path-finding. This is the first demonstration of a genetic interaction between Dg and InR.
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Affiliation(s)
- Halyna R Shcherbata
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Andriy S Yatsenko
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Ivan Franko National University in Lviv, Lviv, Ukraine
| | - Larissa Patterson
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Vanita D Sood
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Uri Nudel
- Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - David Yaffe
- Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - David Baker
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Hannele Ruohola-Baker
- Department of Biochemistry, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Department of Biochemistry, University of Washington, Box 357350, Seattle, WA 98195, USA. Tel.: +1 206 543 1710; Fax: +1 206 685 1792; E-mail:
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29
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Kaletta T, Hengartner MO. Finding function in novel targets: C. elegans as a model organism. Nat Rev Drug Discov 2006; 5:387-98. [PMID: 16672925 DOI: 10.1038/nrd2031] [Citation(s) in RCA: 674] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Despite its apparent simplicity, the nematode worm Caenorhabditis elegans has developed into an important model for biomedical research, particularly in the functional characterization of novel drug targets that have been identified using genomics technologies. The cellular complexity and the conservation of disease pathways between C. elegans and higher organisms, together with the simplicity and cost-effectiveness of cultivation, make for an effective in vivo model that is amenable to whole-organism high-throughput compound screens and large-scale target validation. This review describes how C. elegans models can be used to advance our understanding of the molecular mechanisms of drug action and disease pathogenesis.
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30
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Matthies DS, Fleming PA, Wilkes DM, Blakely RD. The Caenorhabditis elegans choline transporter CHO-1 sustains acetylcholine synthesis and motor function in an activity-dependent manner. J Neurosci 2006; 26:6200-12. [PMID: 16763028 PMCID: PMC6675188 DOI: 10.1523/jneurosci.5036-05.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cholinergic neurotransmission supports motor, autonomic, and cognitive function and is compromised in myasthenias, cardiovascular diseases, and neurodegenerative disorders. Presynaptic uptake of choline via the sodium-dependent, hemicholinium-3-sensitive choline transporter (CHT) is believed to sustain acetylcholine (ACh) synthesis and release. Analysis of this hypothesis in vivo is limited in mammals because of the toxicity of CHT antagonists and the early postnatal lethality of CHT-/- mice (Ferguson et al., 2004). In Caenorhabditis elegans, in which cholinergic signaling supports motor activity and mutant alleles impacting ACh secretion and response can be propagated, we investigated the contribution of CHT (CHO-1) to facets of cholinergic neurobiology. Using the cho-1 promoter to drive expression of a translational, green fluorescent protein-CHO-1 fusion (CHO-1:GFP) in wild-type and kinesin (unc-104) mutant backgrounds, we establish in the living nematode that the transporter localizes to cholinergic synapses, and likely traffics on synaptic vesicles. Using embryonic primary cultures, we demonstrate that CHO-1 mediates hemicholinium-3-sensitive, high-affinity choline uptake that can be enhanced with depolarization in a Ca(2+)-dependent manner supporting ACh synthesis. Although homozygous cho-1 null mutants are viable, they possess 40% less ACh than wild-type animals and display stress-dependent defects in motor activity. In a choline-free liquid environment, cho-1 mutants demonstrate premature paralysis relative to wild-type animals. Our findings establish a requirement for presynaptic choline transport activity in vivo in a model amenable to a genetic dissection of CHO-1 regulation.
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Johnson RP, Kang SH, Kramer JM. C. elegans dystroglycan DGN-1 functions in epithelia and neurons, but not muscle, and independently of dystrophin. Development 2006; 133:1911-21. [PMID: 16611689 DOI: 10.1242/dev.02363] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The C. elegans dystroglycan (DG) homolog DGN-1 is expressed in epithelia and neurons, and localizes to basement membrane (BM) surfaces. Unlike vertebrate DG, DGN-1 is not expressed in muscle or required for muscle function. dgn-1 null mutants are viable but sterile owing to severe disorganization of the somatic gonad epithelium, and show defects in vulval and excretory cell epithelia and in motoneuron axon guidance. The defects resemble those of epi-1 laminin alphaB mutants, suggesting that DGN-1 serves as a receptor for laminin. dgn-1(0)/+ animals are fertile but show gonad migration defects in addition to the defects seen in homozygotes, indicating that DGN-1 function is dosage sensitive. Phenotypic analyses show that DGN-1 and dystrophin-associated protein complex (DAPC) components have distinct and independent functions, in contrast to the situation in vertebrate muscle. The DAPC-independent functions of DGN-1 in epithelia and neurons suggest that vertebrate DG may also act independently of dystrophin/utrophin in non-muscle tissues.
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Affiliation(s)
- Robert P Johnson
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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van der Plas MC, Pilgram GSK, Plomp JJ, de Jong A, Fradkin LG, Noordermeer JN. Dystrophin is required for appropriate retrograde control of neurotransmitter release at the Drosophila neuromuscular junction. J Neurosci 2006; 26:333-44. [PMID: 16399704 PMCID: PMC6674336 DOI: 10.1523/jneurosci.4069-05.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations in the human dystrophin gene cause the Duchenne and Becker muscular dystrophies. The Dystrophin protein provides a structural link between the muscle cytoskeleton and extracellular matrix to maintain muscle integrity. Recently, Dystrophin has also been found to act as a scaffold for several signaling molecules, but the roles of dystrophin-mediated signaling pathways remain unknown. To further our understanding of this aspect of the function of dystrophin, we have generated Drosophila mutants that lack the large dystrophin isoforms and analyzed their role in synapse function at the neuromuscular junction. In expression and rescue studies, we show that lack of the large dystrophin isoforms in the postsynaptic muscle cell leads to elevated evoked neurotransmitter release from the presynaptic apparatus. Overall synapse size, the size of the readily releasable vesicle pool as assessed with hypertonic shock, and the number of presynaptic neurotransmitter release sites (active zones) are not changed in the mutants. Short-term synaptic facilitation of evoked transmitter release is decreased in the mutants, suggesting that the absence of dystrophin results in increased probability of release. Absence of the large dystrophin isoforms does not lead to changes in muscle cell morphology or alterations in the postsynaptic electrical response to spontaneously released neurotransmitter. Therefore, postsynaptic glutamate receptor function does not appear to be affected. Our results indicate that the postsynaptically localized scaffolding protein Dystrophin is required for appropriate control of neuromuscular synaptic homeostasis.
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Affiliation(s)
- Mariska C van der Plas
- Department of Molecular and Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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Ribeiro FM, Black SAG, Prado VF, Rylett RJ, Ferguson SSG, Prado MAM. The "ins" and "outs" of the high-affinity choline transporter CHT1. J Neurochem 2006; 97:1-12. [PMID: 16524384 DOI: 10.1111/j.1471-4159.2006.03695.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maintenance of acetylcholine (ACh) synthesis depends on the activity of the high-affinity choline transporter (CHT1), which is responsible for the reuptake of choline from the synaptic cleft into presynaptic neurons. In this review, we discuss the current understanding of mechanisms involved in the cellular trafficking of CHT1. CHT1 protein is mainly found in intracellular organelles, such as endosomal compartments and synaptic vesicles. The presence of CHT1 at the plasma membrane is limited by rapid endocytosis of the transporter in clathrin-coated pits in a mechanism dependent on a dileucine-like motif present in the carboxyl-terminal region of the transporter. The intracellular pool of CHT1 appears to constitute a reserve pool of transporters, important for maintenance of cholinergic neurotransmission. However, the physiological basis of the presence of CHT1 in intracellular organelles is not fully understood. Current knowledge about CHT1 indicates that stimulated and constitutive exocytosis, in addition to endocytosis, will have major consequences for regulating choline uptake. Future investigations of CHT1 trafficking should elucidate such regulatory mechanisms, which may aid in understanding the pathophysiology of diseases that affect cholinergic neurons, such as Alzheimer's disease.
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Affiliation(s)
- Fabiola M Ribeiro
- Departamento de Bioquímica-Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Carre-Pierrat M, Grisoni K, Gieseler K, Mariol MC, Martin E, Jospin M, Allard B, Ségalat L. The SLO-1 BK channel of Caenorhabditis elegans is critical for muscle function and is involved in dystrophin-dependent muscle dystrophy. J Mol Biol 2006; 358:387-95. [PMID: 16527307 DOI: 10.1016/j.jmb.2006.02.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/11/2006] [Accepted: 02/14/2006] [Indexed: 10/25/2022]
Abstract
The Caenorhabditis elegans SLO-1 channel belongs to the family of calcium-activated large conductance BK potassium channels. SLO-1 has been shown to be involved in neurotransmitter release and ethanol response. Here, we report that SLO-1 also has a critical role in muscles. Inactivation of the slo-1 gene in muscles leads to phenotypes similar to those caused by mutations of the dystrophin homologue dys-1. Notably, slo-1 mutations result in a progressive muscle degeneration when put into a sensitized genetic background. slo-1 localization was observed by gfp reporter gene in both the M-line and the dense bodies (Z line) of the C.elegans body-wall muscles. Using the inside-out configuration of the patch clamp technique on body-wall muscle cells of acutely dissected wild-type worms, we characterized a Ca2+-activated K+ channel that was identified unambiguously as SLO-1. Since neither the abundance nor the conductance of SLO-1 was changed significantly in dys-1 mutants compared to wild-type animals, it is likely that the inactivation of dys-1 causes a misregulation of SLO-1. All in all, these results indicate that SLO-1 function in C.elegans muscles is related to the dystrophin homologue DYS-1.
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Affiliation(s)
- Maité Carre-Pierrat
- CGMC, CNRS-UMR 5534, Université C. Bernard Lyon-1, 69622 Villeurbanne, France
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Wells WA. Dystrophic muscles get overexcited. J Biophys Biochem Cytol 2004. [PMCID: PMC2253915 DOI: 10.1083/jcb1666rr3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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