1
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Moody JC, Qadota H, Benian GM. The RhoGAP RRC-1 is required for the assembly or stability of integrin adhesion complexes and is a member of the PIX pathway in muscle. Mol Biol Cell 2024; 35:ar58. [PMID: 38446619 PMCID: PMC11064667 DOI: 10.1091/mbc.e23-03-0095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 02/20/2024] [Accepted: 02/28/2024] [Indexed: 03/08/2024] Open
Abstract
GTPases cycle between active GTP bound and inactive GDP bound forms. Exchange of GDP for GTP is catalyzed by guanine nucleotide exchange factors (GEFs). GTPase activating proteins (GAPs) accelerate GTP hydrolysis, to promote the GDP bound form. We reported that the RacGEF, PIX-1, is required for assembly of integrin adhesion complexes (IAC) in striated muscle of Caenorhabditis elegans. In C. elegans, IACs are found at the muscle cell boundaries (MCBs), and bases of sarcomeric M-lines and dense bodies (Z-disks). Screening C. elegans mutants in proteins containing RhoGAP domains revealed that loss of function of rrc-1 results in loss of IAC components at MCBs, disorganization of M-lines and dense bodies, and reduced whole animal locomotion. RRC-1 localizes to MCBs, like PIX-1. The localization of RRC-1 at MCBs requires PIX-1, and the localization of PIX-1 requires RRC-1. Loss of function of CED-10 (Rac) shows lack of PIX-1 and RRC-1 at MCBs. RRC-1 exists in a complex with PIX-1. Transgenic rescue of rrc-1 was achieved with wild type RRC-1 but not RRC-1 with a missense mutation in a highly conserved residue of the RhoGAP domain. Our results are consistent with RRC-1 being a RhoGAP for the PIX pathway in muscle.
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Affiliation(s)
| | - Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Guy M. Benian
- Department of Pathology, Emory University, Atlanta, GA 30322
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2
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Greiffer L, Liebau E, Herrmann FC, Spiegler V. Condensed tannins act as anthelmintics by increasing the rigidity of the nematode cuticle. Sci Rep 2022; 12:18850. [PMID: 36344622 PMCID: PMC9640668 DOI: 10.1038/s41598-022-23566-2] [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: 09/02/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Tannins and tanniferous plant extracts have been discussed as sustainable means for helminth control in the past two decades in response to a dramatic increase of resistances towards standard anthelmintics. While their bioactivities have been broadly investigated in vitro and in vivo, less is known about their mode of action in nematodes, apart from their protein binding properties. In the current study we therefore investigated the impact of a phytochemically well characterized plant extract from Combretum mucronatum, known to contain procyanidins as the active compounds, on the model organism Caenorhabditis elegans. By different microscopic techniques, the cuticle was identified as the main binding site for tannins, whereas underlying tissues did not seem to be affected. In addition to disruptions of the cuticle structure, molting defects occurred at all larval stages. Finally, an increased rigidity of the nematodes' cuticle due to binding of tannins was confirmed by force spectroscopic measurements. This could be a key finding to explain several anthelmintic activities reported for tannins, especially impairment of molting or exsheathment as well as locomotion.
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Affiliation(s)
- Luise Greiffer
- grid.5949.10000 0001 2172 9288Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany
| | - Eva Liebau
- grid.5949.10000 0001 2172 9288Institute of Integrative Cell Biology and Physiology, University of Münster, Münster, Germany
| | - Fabian C. Herrmann
- grid.5949.10000 0001 2172 9288Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany
| | - Verena Spiegler
- grid.5949.10000 0001 2172 9288Institute for Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany
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3
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Imaging of Actin Cytoskeleton in the Nematode Caenorhabditis elegans. Methods Mol Biol 2021. [PMID: 34542852 DOI: 10.1007/978-1-0716-1661-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The nematode Caenorhabditis elegans is one of the major model organisms in cell and developmental biology. This organism is easy to culture in laboratories and suitable for microscopic investigation of the cytoskeleton. Because the worms are small and transparent, the actin cytoskeleton in many tissues and cells can be observed with appropriate visualization techniques without sectioning or dissection. This chapter describes the introduction to representative methods for imaging the actin cytoskeleton in C. elegans and a protocol for staining worms with fluorescent phalloidin.
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4
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Moody JC, Qadota H, Reedy AR, Okafor CD, Shanmugan N, Matsunaga Y, Christian CJ, Ortlund EA, Benian GM. The Rho-GEF PIX-1 directs assembly or stability of lateral attachment structures between muscle cells. Nat Commun 2020; 11:5010. [PMID: 33024114 PMCID: PMC7538588 DOI: 10.1038/s41467-020-18852-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 09/15/2020] [Indexed: 01/11/2023] Open
Abstract
PIX proteins are guanine nucleotide exchange factors (GEFs) that activate Rac and Cdc42, and are known to have numerous functions in various cell types. Here, we show that a PIX protein has an important function in muscle. From a genetic screen in C. elegans, we found that pix-1 is required for the assembly of integrin adhesion complexes (IACs) at borders between muscle cells, and is required for locomotion of the animal. A pix-1 null mutant has a reduced level of activated Rac in muscle. PIX-1 localizes to IACs at muscle cell boundaries, M-lines and dense bodies. Mutations in genes encoding proteins at known steps of the PIX signaling pathway show defects at muscle cell boundaries. A missense mutation in a highly conserved residue in the RacGEF domain results in normal levels of PIX-1 protein, but a reduced level of activated Rac in muscle, and abnormal IACs at muscle cell boundaries.
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Affiliation(s)
- Jasmine C Moody
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA
| | - Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA
| | - April R Reedy
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA
| | - C Denise Okafor
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - Niveda Shanmugan
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA
| | - Yohei Matsunaga
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA
| | | | - Eric A Ortlund
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - Guy M Benian
- Department of Pathology, Emory University, Atlanta, GA, 30322, USA.
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5
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Egge N, Arneaud SLB, Wales P, Mihelakis M, McClendon J, Fonseca RS, Savelle C, Gonzalez I, Ghorashi A, Yadavalli S, Lehman WJ, Mirzaei H, Douglas PM. Age-Onset Phosphorylation of a Minor Actin Variant Promotes Intestinal Barrier Dysfunction. Dev Cell 2020; 51:587-601.e7. [PMID: 31794717 DOI: 10.1016/j.devcel.2019.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 09/17/2019] [Accepted: 11/03/2019] [Indexed: 12/28/2022]
Abstract
Age-associated decay of intercellular interactions impairs the cells' capacity to tightly associate within tissues and form a functional barrier. This barrier dysfunction compromises organ physiology and contributes to systemic failure. The actin cytoskeleton represents a key determinant in maintaining tissue architecture. Yet, it is unclear how age disrupts the actin cytoskeleton and how this, in turn, promotes mortality. Here, we show that an uncharacterized phosphorylation of a low-abundant actin variant, ACT-5, compromises integrity of the C. elegans intestinal barrier and accelerates pathogenesis. Age-related loss of the heat-shock transcription factor, HSF-1, disrupts the JUN kinase and protein phosphatase I equilibrium which increases ACT-5 phosphorylation within its troponin binding site. Phosphorylated ACT-5 accelerates decay of the intestinal subapical terminal web and impairs its interactions with cell junctions. This compromises barrier integrity, promotes pathogenesis, and drives mortality. Thus, we provide the molecular mechanism by which age-associated loss of specialized actin networks impacts tissue integrity.
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Affiliation(s)
- Nathan Egge
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Medical Scientist Training Program, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sonja L B Arneaud
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Pauline Wales
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Melina Mihelakis
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jacob McClendon
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rene Solano Fonseca
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Charles Savelle
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ian Gonzalez
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Atossa Ghorashi
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - William J Lehman
- Department of Structural Biology, Boston University, Boston, MA 02118, USA
| | - Hamid Mirzaei
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Peter M Douglas
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA; Hamon Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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6
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Ryu D, Zhang H, Ropelle ER, Sorrentino V, Mázala DAG, Mouchiroud L, Marshall PL, Campbell MD, Ali AS, Knowels GM, Bellemin S, Iyer SR, Wang X, Gariani K, Sauve AA, Cantó C, Conley KE, Walter L, Lovering RM, Chin ER, Jasmin BJ, Marcinek DJ, Menzies KJ, Auwerx J. NAD+ repletion improves muscle function in muscular dystrophy and counters global PARylation. Sci Transl Med 2017; 8:361ra139. [PMID: 27798264 DOI: 10.1126/scitranslmed.aaf5504] [Citation(s) in RCA: 189] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 09/12/2016] [Indexed: 12/25/2022]
Abstract
Neuromuscular diseases are often caused by inherited mutations that lead to progressive skeletal muscle weakness and degeneration. In diverse populations of normal healthy mice, we observed correlations between the abundance of mRNA transcripts related to mitochondrial biogenesis, the dystrophin-sarcoglycan complex, and nicotinamide adenine dinucleotide (NAD+) synthesis, consistent with a potential role for the essential cofactor NAD+ in protecting muscle from metabolic and structural degeneration. Furthermore, the skeletal muscle transcriptomes of patients with Duchene's muscular dystrophy (DMD) and other muscle diseases were enriched for various poly[adenosine 5'-diphosphate (ADP)-ribose] polymerases (PARPs) and for nicotinamide N-methyltransferase (NNMT), enzymes that are major consumers of NAD+ and are involved in pleiotropic events, including inflammation. In the mdx mouse model of DMD, we observed significant reductions in muscle NAD+ levels, concurrent increases in PARP activity, and reduced expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for NAD+ biosynthesis. Replenishing NAD+ stores with dietary nicotinamide riboside supplementation improved muscle function and heart pathology in mdx and mdx/Utr-/- mice and reversed pathology in Caenorhabditis elegans models of DMD. The effects of NAD+ repletion in mdx mice relied on the improvement in mitochondrial function and structural protein expression (α-dystrobrevin and δ-sarcoglycan) and on the reductions in general poly(ADP)-ribosylation, inflammation, and fibrosis. In combination, these studies suggest that the replenishment of NAD+ may benefit patients with muscular dystrophies or other neuromuscular degenerative conditions characterized by the PARP/NNMT gene expression signatures.
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Affiliation(s)
- Dongryeol Ryu
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Hongbo Zhang
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Eduardo R Ropelle
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.,Laboratory of Molecular Biology of Exercise, School of Applied Science, University of Campinas, CEP 13484-350 Limeira, São Paulo, Brazil
| | - Vincenzo Sorrentino
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Davi A G Mázala
- Department of Kinesiology, School of Public Health, University of Maryland, College Park, MD 20742, USA
| | - Laurent Mouchiroud
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Philip L Marshall
- Interdisciplinary School of Health Sciences, University of Ottawa Brain and Mind Research Institute and Centre for Neuromuscular Disease, Ottawa, Ontario K1H 8M5, Canada
| | - Matthew D Campbell
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Amir Safi Ali
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Gary M Knowels
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Stéphanie Bellemin
- Centre de Génétique et de Physiologie Moléculaires et Cellulaires, Université Claude Bernard Lyon 1, CNRS UMR 5534, 69622 Villeurbanne, France
| | - Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Xu Wang
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Karim Gariani
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Anthony A Sauve
- Department of Pharmacology, Weill Cornell Medical School, New York, NY 10065, USA
| | - Carles Cantó
- Nestlé Institute of Health Sciences, 1015 Lausanne, Switzerland
| | - Kevin E Conley
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Ludivine Walter
- Centre de Génétique et de Physiologie Moléculaires et Cellulaires, Université Claude Bernard Lyon 1, CNRS UMR 5534, 69622 Villeurbanne, France
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eva R Chin
- Department of Kinesiology, School of Public Health, University of Maryland, College Park, MD 20742, USA
| | - Bernard J Jasmin
- Department of Cellular and Molecular Medicine and Centre for Neuromuscular Disease, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - David J Marcinek
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Keir J Menzies
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland. .,Interdisciplinary School of Health Sciences, University of Ottawa Brain and Mind Research Institute and Centre for Neuromuscular Disease, Ottawa, Ontario K1H 8M5, Canada
| | - Johan Auwerx
- Laboratory of Integrative and Systems Physiology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
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7
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Preventing Illegitimate Extrasynaptic Acetylcholine Receptor Clustering Requires the RSU-1 Protein. J Neurosci 2017; 36:6525-37. [PMID: 27307240 DOI: 10.1523/jneurosci.3733-15.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 05/06/2016] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED Diffuse extrasynaptic neurotransmitter receptors constitute an abundant pool of receptors that can be recruited to modulate synaptic strength. Whether the diffuse distribution of receptors in extrasynaptic membranes is a default state or is actively controlled remains essentially unknown. Here we show that RSU-1 (Ras Suppressor-1) is required for the proper distribution of extrasynaptic acetylcholine receptors (AChRs) in Caenorhabditis elegans muscle cells. RSU-1 is an evolutionary conserved cytoplasmic protein that contains multiple leucine-rich repeats (LRRs) and interacts with integrin-dependent adhesion complexes. In rsu-1 mutants, neuromuscular junctions differentiate as in the wild type, but AChRs assemble into ectopic clusters that progressively enlarge during development. As a consequence, the synaptic content of AChRs is reduced. Our study provides the first evidence that an RSU-1-dependent active mechanism maintains extrasynaptic receptors dispersed and indirectly regulates synapse maturation. SIGNIFICANCE STATEMENT Using Caenorhabditis elegans neuromuscular junction as a model synapse, we uncovered a novel mechanism that regulates the distribution of acetylcholine receptors (AChRs). In an unbiased visual screen for mutants with abnormal AChR distribution, we isolated the ras suppressor 1 (rsu-1) mutant based on the presence of large extrasynaptic clusters. We show that disrupting rsu-1 causes spontaneous clustering of extrasynaptic receptors that are normally dispersed, independently of synaptic cues. These clusters outcompete synaptic domains and cause a decrease of synaptic receptor content. These results indicate that the diffuse state of extrasynaptic receptors is not a default state that is simply explained by the lack of synaptic cues but necessitates additional proteins to prevent spontaneous clustering, a concept that is relevant for developmental and pathological situations.
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8
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Heat-Induced Calcium Leakage Causes Mitochondrial Damage in Caenorhabditis elegans Body-Wall Muscles. Genetics 2017; 206:1985-1994. [PMID: 28576866 PMCID: PMC5560802 DOI: 10.1534/genetics.117.202747] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 05/23/2017] [Indexed: 01/22/2023] Open
Abstract
Acute onset of organ failure in heatstroke is triggered by rhabdomyolysis of skeletal muscle. Here, we showed that elevated temperature increases free cytosolic Ca2+ [Ca2+]f from RYR (ryanodine receptor)/UNC-68in vivo in the muscles of an experimental model animal, the nematode Caenorhabditis elegans. This subsequently leads to mitochondrial fragmentation and dysfunction, and breakdown of myofilaments similar to rhabdomyolysis. In addition, treatment with an inhibitor of RYR (dantrolene) or activation of FoxO (Forkhead box O)/DAF-16 is effective against heat-induced muscle damage. Acute onset of organ failure in heatstroke is triggered by rhabdomyolysis of skeletal muscle. To gain insight into heat-induced muscle breakdown, we investigated alterations of Ca2+ homeostasis and mitochondrial morphology in vivo in body-wall muscles of C. elegans exposed to elevated temperature. Heat stress for 3 hr at 35° increased the concentration of [Ca2+]f, and led to mitochondrial fragmentation and subsequent dysfunction in the muscle cells. A similar mitochondrial fragmentation phenotype is induced in the absence of heat stress by treatment with a calcium ionophore, ionomycin. Mutation of the unc-68 gene, which encodes the ryanodine receptor that is linked to Ca2+ release from the sarcoplasmic reticulum, could suppress the mitochondrial dysfunction, muscle degeneration, and reduced mobility and life span induced by heat stress. In addition, in a daf-2 mutant, in which the DAF-16/FoxO transcription factor is activated, resistance to calcium overload, mitochondrial fragmentation, and dysfunction was observed. These findings reveal that heat-induced Ca2+ accumulation causes mitochondrial damage and consequently induces muscle breakdown.
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9
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Cellular Proteomes Drive Tissue-Specific Regulation of the Heat Shock Response. G3-GENES GENOMES GENETICS 2017; 7:1011-1018. [PMID: 28143946 PMCID: PMC5345702 DOI: 10.1534/g3.116.038232] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The heat shock response (HSR) is a cellular stress response that senses protein misfolding and restores protein folding homeostasis, or proteostasis. We previously identified an HSR regulatory network in Caenorhabditis elegans consisting of highly conserved genes that have important cellular roles in maintaining proteostasis. Unexpectedly, the effects of these genes on the HSR are distinctly tissue-specific. Here, we explore this apparent discrepancy and find that muscle-specific regulation of the HSR by the TRiC/CCT chaperonin is not driven by an enrichment of TRiC/CCT in muscle, but rather by the levels of one of its most abundant substrates, actin. Knockdown of actin subunits reduces induction of the HSR in muscle upon TRiC/CCT knockdown; conversely, overexpression of an actin subunit sensitizes the intestine so that it induces the HSR upon TRiC/CCT knockdown. Similarly, intestine-specific HSR regulation by the signal recognition particle (SRP), a component of the secretory pathway, is driven by the vitellogenins, some of the most abundant secretory proteins. Together, these data indicate that the specific protein folding requirements from the unique cellular proteomes sensitizes each tissue to disruption of distinct subsets of the proteostasis network. These findings are relevant for tissue-specific, HSR-associated human diseases such as cancer and neurodegenerative diseases. Additionally, we characterize organismal phenotypes of actin overexpression including a shortened lifespan, supporting a recent hypothesis that maintenance of the actin cytoskeleton is an important factor for longevity.
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10
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Ono S. Regulation of structure and function of sarcomeric actin filaments in striated muscle of the nematode Caenorhabditis elegans. Anat Rec (Hoboken) 2015; 297:1548-59. [PMID: 25125169 DOI: 10.1002/ar.22965] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 02/26/2014] [Accepted: 02/26/2014] [Indexed: 02/01/2023]
Abstract
The nematode Caenorhabditis elegans has been used as a valuable system to study structure and function of striated muscle. The body wall muscle of C. elegans is obliquely striated muscle with highly organized sarcomeric assembly of actin, myosin, and other accessory proteins. Genetic and molecular biological studies in C. elegans have identified a number of genes encoding structural and regulatory components for the muscle contractile apparatuses, and many of them have counterparts in mammalian cardiac and skeletal muscles or striated muscles in other invertebrates. Applicability of genetics, cell biology, and biochemistry has made C. elegans an excellent system to study mechanisms of muscle contractility and assembly and maintenance of myofibrils. This review focuses on the regulatory mechanisms of structure and function of actin filaments in the C. elegans body wall muscle. Sarcomeric actin filaments in C. elegans muscle are associated with the troponin-tropomyosin system that regulates the actin-myosin interaction. Proteins that bind to the side and ends of actin filaments support ordered assembly of thin filaments. Furthermore, regulators of actin dynamics play important roles in initial assembly, growth, and maintenance of sarcomeres. The knowledge acquired in C. elegans can serve as bases to understand the basic mechanisms of muscle structure and function.
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Affiliation(s)
- Shoichiro Ono
- Department of Pathology, Emory University, Atlanta, Georgia; Department of Cell Biology, Emory University, Atlanta, Georgia
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11
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Saegusa K, Sato M, Sato K, Nakajima-Shimada J, Harada A, Sato K. Caenorhabditis elegans chaperonin CCT/TRiC is required for actin and tubulin biogenesis and microvillus formation in intestinal epithelial cells. Mol Biol Cell 2014; 25:3095-104. [PMID: 25143409 PMCID: PMC4196862 DOI: 10.1091/mbc.e13-09-0530] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Intestinal epithelial cells have unique apical membrane structures, known as microvilli, that contain bundles of actin microfilaments. In this study, we report that Caenorhabditis elegans cytosolic chaperonin containing TCP-1 (CCT) is essential for proper formation of microvilli in intestinal cells. In intestinal cells of cct-5(RNAi) animals, a substantial amount of actin is lost from the apical area, forming large aggregates in the cytoplasm, and the apical membrane is deformed into abnormal, bubble-like structures. The length of the intestinal microvilli is decreased in these animals. However, the overall actin protein levels remain relatively unchanged when CCT is depleted. We also found that CCT depletion causes a reduction in the tubulin levels and disorganization of the microtubule network. In contrast, the stability and localization of intermediate filament protein IFB-2, which forms a dense filamentous network underneath the apical surface, appears to be superficially normal in CCT-deficient cells, suggesting substrate specificity of CCT in the folding of filamentous cytoskeletons in vivo. Our findings demonstrate physiological functions of CCT in epithelial cell morphogenesis using whole animals.
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Affiliation(s)
- Keiko Saegusa
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Miyuki Sato
- Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Katsuya Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | | | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
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12
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Giacomotto J, Brouilly N, Walter L, Mariol MC, Berger J, Ségalat L, Becker TS, Currie PD, Gieseler K. Chemical genetics unveils a key role of mitochondrial dynamics, cytochrome c release and IP3R activity in muscular dystrophy. Hum Mol Genet 2013; 22:4562-78. [PMID: 23804750 DOI: 10.1093/hmg/ddt302] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a neuromuscular disease caused by mutations in the dystrophin gene. The subcellular mechanisms of DMD remain poorly understood and there is currently no curative treatment available. Using a Caenorhabditis elegans model for DMD as a pharmacologic and genetic tool, we found that cyclosporine A (CsA) reduces muscle degeneration at low dose and acts, at least in part, through a mitochondrial cyclophilin D, CYN-1. We thus hypothesized that CsA acts on mitochondrial permeability modulation through cyclophilin D inhibition. Mitochondrial patterns and dynamics were analyzed, which revealed dramatic mitochondrial fragmentation not only in dystrophic nematodes, but also in a zebrafish model for DMD. This abnormal mitochondrial fragmentation occurs before any obvious sign of degeneration can be detected. Moreover, we demonstrate that blocking/delaying mitochondrial fragmentation by knocking down the fission-promoting gene drp-1 reduces muscle degeneration and improves locomotion abilities of dystrophic nematodes. Further experiments revealed that cytochrome c is involved in muscle degeneration in C. elegans and seems to act, at least in part, through an interaction with the inositol trisphosphate receptor calcium channel, ITR-1. Altogether, our findings reveal that mitochondria play a key role in the early process of muscle degeneration and may be a target of choice for the design of novel therapeutics for DMD. In addition, our results provide the first indication in the nematode that (i) mitochondrial permeability transition can occur and (ii) cytochrome c can act in cell death.
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Affiliation(s)
- Jean Giacomotto
- Brain and Mind Research Institute, Sydney Medical School, University of Sydney, NSW 2050, Australia
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13
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Lecroisey C, Brouilly N, Qadota H, Mariol MC, Rochette NC, Martin E, Benian GM, Ségalat L, Mounier N, Gieseler K. ZYX-1, the unique zyxin protein of Caenorhabditis elegans, is involved in dystrophin-dependent muscle degeneration. Mol Biol Cell 2013; 24:1232-49. [PMID: 23427270 PMCID: PMC3623643 DOI: 10.1091/mbc.e12-09-0679] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In vertebrates, zyxin is a LIM-domain protein belonging to a family composed of seven members. We show that the nematode Caenorhabditis elegans has a unique zyxin-like protein, ZYX-1, which is the orthologue of the vertebrate zyxin subfamily composed of zyxin, migfilin, TRIP6, and LPP. The ZYX-1 protein is expressed in the striated body-wall muscles and localizes at dense bodies/Z-discs and M-lines, as well as in the nucleus. In yeast two-hybrid assays ZYX-1 interacts with several known dense body and M-line proteins, including DEB-1 (vinculin) and ATN-1 (α-actinin). ZYX-1 is mainly localized in the middle region of the dense body/Z-disk, overlapping the apical and basal regions containing, respectively, ATN-1 and DEB-1. The localization and dynamics of ZYX-1 at dense bodies depend on the presence of ATN-1. Fluorescence recovery after photobleaching experiments revealed a high mobility of the ZYX-1 protein within muscle cells, in particular at dense bodies and M-lines, indicating a peripheral and dynamic association of ZYX-1 at these muscle adhesion structures. A portion of the ZYX-1 protein shuttles from the cytoplasm into the nucleus, suggesting a role for ZYX-1 in signal transduction. We provide evidence that the zyx-1 gene encodes two different isoforms, ZYX-1a and ZYX-1b, which exhibit different roles in dystrophin-dependent muscle degeneration occurring in a C. elegans model of Duchenne muscular dystrophy.
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Barua B, Fagnant PM, Winkelmann DA, Trybus KM, Hitchcock-DeGregori SE. A periodic pattern of evolutionarily conserved basic and acidic residues constitutes the binding interface of actin-tropomyosin. J Biol Chem 2013; 288:9602-9609. [PMID: 23420843 DOI: 10.1074/jbc.m113.451161] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Actin filament cytoskeletal and muscle functions are regulated by actin binding proteins using a variety of mechanisms. A universal actin filament regulator is the protein tropomyosin, which binds end-to-end along the length of the filament. The actin-tropomyosin filament structure is unknown, but there are atomic models in different regulatory states based on electron microscopy reconstructions, computational modeling of actin-tropomyosin, and docking of atomic resolution structures of tropomyosin to actin filament models. Here, we have tested models of the actin-tropomyosin interface in the "closed state" where tropomyosin binds to actin in the absence of myosin or troponin. Using mutagenesis coupled with functional analyses, we determined residues of actin and tropomyosin required for complex formation. The sites of mutations in tropomyosin were based on an evolutionary analysis and revealed a pattern of basic and acidic residues in the first halves of the periodic repeats (periods) in tropomyosin. In periods P1, P4, and P6, basic residues are most important for actin affinity, in contrast to periods P2, P3, P5, and P7, where both basic and acidic residues or predominantly acidic residues contribute to actin affinity. Hydrophobic interactions were found to be relatively less important for actin binding. We mutated actin residues in subdomains 1 and 3 (Asp(25)-Glu(334)-Lys(326)-Lys(328)) that are poised to make electrostatic interactions with the residues in the repeating motif on tropomyosin in the models. Tropomyosin failed to bind mutant actin filaments. Our mutagenesis studies provide the first experimental support for the atomic models of the actin-tropomyosin interface.
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Affiliation(s)
- Bipasha Barua
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854; Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854.
| | - Patricia M Fagnant
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405
| | - Donald A Winkelmann
- Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Kathleen M Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405
| | - Sarah E Hitchcock-DeGregori
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854; Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
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15
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Wang LC, Chen KY, Pan H, Wu CC, Chen PH, Liao YT, Li C, Huang ML, Hsiao KM. Muscleblind participates in RNA toxicity of expanded CAG and CUG repeats in Caenorhabditis elegans. Cell Mol Life Sci 2011; 68:1255-67. [PMID: 20848157 PMCID: PMC11114631 DOI: 10.1007/s00018-010-0522-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 08/06/2010] [Accepted: 08/30/2010] [Indexed: 01/22/2023]
Abstract
We have utilized Caenorhabditis elegans as a model to investigate the toxicity and underlying mechanism of untranslated CAG repeats in comparison to CUG repeats. Our results indicate that CAG repeats can be toxic at the RNA level in a length-dependent manner, similar to that of CUG repeats. Both CAG and CUG repeats of toxic length form nuclear foci and co-localize with C. elegans muscleblind (CeMBL), implying that CeMBL may play a role in repeat RNA toxicity. Consistently, the phenotypes of worms expressing toxic CAG and CUG repeats, including shortened life span and reduced motility rate, were partially reversed by CeMbl over-expression. These results provide the first experimental evidence to show that the RNA toxicity induced by expanded CAG and CUG repeats can be mediated, at least in part, through the functional alteration of muscleblind in worms.
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Affiliation(s)
- Li-Chun Wang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, 402 Taiwan
| | - Kuan-Yu Chen
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
| | - Huichin Pan
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, 402 Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung, 402 Taiwan
| | - Chia-Chieh Wu
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
| | - Po-Hsuan Chen
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
| | - Yuan-Ting Liao
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
| | - Chin Li
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
- Department of Life Science, National Chung Cheng University, 168, University Road, Min-Hsiung, Chia-Yi, 62102 Taiwan, ROC
| | - Min-Lang Huang
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
- Department of Life Science, National Chung Cheng University, 168, University Road, Min-Hsiung, Chia-Yi, 62102 Taiwan, ROC
| | - Kuang-Ming Hsiao
- Institute of Molecular Biology, National Chung Cheng University, Chia-Yi, 621 Taiwan
- Department of Life Science, National Chung Cheng University, 168, University Road, Min-Hsiung, Chia-Yi, 62102 Taiwan, ROC
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16
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Giacomotto J, Pertl C, Borrel C, Walter MC, Bulst S, Johnsen B, Baillie DL, Lochmüller H, Thirion C, Ségalat L. Evaluation of the therapeutic potential of carbonic anhydrase inhibitors in two animal models of dystrophin deficient muscular dystrophy. Hum Mol Genet 2009; 18:4089-101. [PMID: 19648295 DOI: 10.1093/hmg/ddp358] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Duchenne Muscular Dystrophy is an inherited muscle degeneration disease for which there is still no efficient treatment. However, compounds active on the disease may already exist among approved drugs but are difficult to identify in the absence of cellular models. We used the Caenorhabditis elegans animal model to screen a collection of 1000 already approved compounds. Two of the most active hits obtained were methazolamide and dichlorphenamide, carbonic anhydrase inhibitors widely used in human therapy. In C. elegans, these drugs were shown to interact with CAH-4, a putative carbonic anhydrase. The therapeutic efficacy of these compounds was further validated in long-term experiments on mdx mice, the mouse model of Duchenne Muscular Dystrophy. Mice were treated for 120 days with food containing methazolamide or dichlorphenamide at two doses each. Musculus tibialis anterior and diaphragm muscles were histologically analyzed and isometric muscle force was measured in M. extensor digitorum longus. Both substances increased the tetanic muscle force in the treated M. extensor digitorum longus muscle group, dichlorphenamide increased the force significantly by 30%, but both drugs failed to increase resistance of muscle fibres to eccentric contractions. Histological analysis revealed a reduction of centrally nucleated fibers in M. tibialis anterior and diaphragm in the treated groups. These studies further demonstrated that a C. elegans-based screen coupled with a mouse model validation strategy can lead to the identification of potential pharmacological agents for rare diseases.
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Affiliation(s)
- Jean Giacomotto
- Centre de Génétique Moléculaire et Cellulaire, UMR 5534, Université Lyon 1, 69622 Villeurbanne Cedex, France
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17
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Increased IP3/Ca2+ signaling compensates depletion of LET-413/DLG-1 in C. elegans epithelial junction assembly. Dev Biol 2008; 327:34-47. [PMID: 19109941 DOI: 10.1016/j.ydbio.2008.11.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 11/18/2008] [Accepted: 11/19/2008] [Indexed: 12/21/2022]
Abstract
The let-413/scribble and dlg-1/discs large genes are key regulators of epithelial cell polarity in C. elegans and other systems but the mechanism how they organize a circumferential junctional belt around the apex of epithelial cells is not well understood. We report here that IP(3)/Ca(2+) signaling is involved in the let-413/dlg-1 pathway for the establishment of epithelial cell polarity during the development in C. elegans. Using RNAi to interfere with let-413 and dlg-1 gene functions during post-embryogenesis, we discovered a requirement for LET-413 and DLG-1 in the polarization of the spermathecal cells. The spermatheca forms an accordion-like organ through which eggs must enter to complete the ovulation process. LET-413- and DLG-1-depleted animals exhibit failure of ovulation. Consistent with this phenotype, the assembly of the apical junction into a continuous belt fails and the PAR-3 protein and microfilaments are no longer localized asymmetrically. All these defects can be suppressed by mutations in IPP-5, an inositol polyphosphate 5-phosphatase and in ITR-1, an inositol triphosphate receptor, which both are supposed to increase the intracellular Ca(2+) level. Analysis of embryogenesis revealed that IP(3)/Ca(2+) signaling is also required during junction assembly in embryonic epithelia.
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Shannon AJ, Tyson T, Dix I, Boyd J, Burnell AM. Systemic RNAi mediated gene silencing in the anhydrobiotic nematode Panagrolaimus superbus. BMC Mol Biol 2008; 9:58. [PMID: 18565215 PMCID: PMC2453295 DOI: 10.1186/1471-2199-9-58] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2008] [Accepted: 06/19/2008] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Gene silencing by RNA interference (RNAi) is a powerful tool for functional genomics. Although RNAi was first described in Caenorhabditis elegans, several nematode species are unable to mount an RNAi response when exposed to exogenous double stranded RNA (dsRNA). These include the satellite model organisms Pristionchus pacificus and Oscheius tipulae. Available data also suggest that the RNAi pathway targeting exogenous dsRNA may not be fully functional in some animal parasitic nematodes. The genus Panagrolaimus contains bacterial feeding nematodes which occupy a diversity of niches ranging from polar, temperate and semi-arid soils to terrestrial mosses. Thus many Panagrolaimus species are adapted to tolerate freezing and desiccation and are excellent systems to study the molecular basis of environmental stress tolerance. We investigated whether Panagrolaimus is susceptible to RNAi to determine whether this nematode could be used in large scale RNAi studies in functional genomics. RESULTS We studied two species: Panagrolaimus sp. PS1159 and Panagrolaimus superbus. Both nematode species displayed embryonic lethal RNAi phenotypes following ingestion of Escherichia coli expressing dsRNA for the C. elegans embryonic lethal genes Ce-lmn-1 and Ce-ran-4. Embryonic lethal RNAi phenotypes were also obtained in both species upon ingestion of dsRNA for the Panagrolaimus genes ef1b and rps-2. Single nematode RT-PCR showed that a significant reduction in mRNA transcript levels occurred for the target ef1b and rps-2 genes in RNAi treated Panagrolaimus sp. 1159 nematodes. Visible RNAi phenotypes were also observed when P. superbus was exposed to dsRNA for structural genes encoding contractile proteins. All RNAi phenotypes were highly penetrant, particularly in P. superbus. CONCLUSION This demonstration that Panagrolaimus is amenable to RNAi by feeding will allow the development of high throughput methods of RNAi screening for P. superbus. This greatly enhances the utility of this nematode as a model system for the study of the molecular biology of anhydrobiosis and cryobiosis and as a possible satellite model nematode for comparative and functional genomics. Our data also identify another nematode infraorder which is amenable to RNAi and provide additional information on the diversity of RNAi phenotypes in nematodes.
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Affiliation(s)
- Adam J Shannon
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Trevor Tyson
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Ilona Dix
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Jacqueline Boyd
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Nottingham Rd., Southwell, NG25 0QF, UK
| | - Ann M Burnell
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
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19
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Sirtuin inhibition protects from the polyalanine muscular dystrophy protein PABPN1. Hum Mol Genet 2008; 17:2108-17. [DOI: 10.1093/hmg/ddn109] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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20
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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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21
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A mutation in CHN-1/CHIP suppresses muscle degeneration in Caenorhabditis elegans. Dev Biol 2007; 312:193-202. [PMID: 17961535 DOI: 10.1016/j.ydbio.2007.09.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 08/24/2007] [Accepted: 09/10/2007] [Indexed: 02/03/2023]
Abstract
Duchenne muscular dystrophy (DMD) is one of the most severe X-linked, inherited diseases of childhood, characterized by progressive muscle wasting and weakness as the consequence of mutations in the dystrophin gene. The protein encoded by dystrophin is a huge cytosolic protein that links the intracellular F-actin filaments to the members of the dystrophin-glycoprotein-complex (DGC). Dystrophin deficiency results in the absence or reduction of complex components that are degraded through an unknown pathway. We show here that muscle degeneration in a Caenorhabditis elegans DMD model is efficiently reduced by downregulation of chn-1, encoding the homologue of the human E3/E4 ubiquitylation enzyme CHIP. A deletion mutant of chn-1 delays the cell death of body-wall muscle cells and improves the motility of animals carrying mutations in dystrophin and MyoD. Elimination of chn-1 function in the musculature, but not in the nervous system, is sufficient for this effect, and can be phenocopied by proteasome inhibitor treatment. This suggests a critical role of CHIP/CHN-1-mediated ubiquitylation in the control of muscle wasting and degeneration and identifies a potential new drug target for the treatment of this disease.
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22
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Ono K, Yu R, Ono S. Structural components of the nonstriated contractile apparatuses in the Caenorhabditis elegans gonadal myoepithelial sheath and their essential roles for ovulation. Dev Dyn 2007; 236:1093-105. [PMID: 17326220 PMCID: PMC1994093 DOI: 10.1002/dvdy.21091] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ovulation in the nematode Caenorhabditis elegans is regulated by complex signal transduction pathways and cell-cell interactions. Myoepithelial sheath cells of the proximal ovary are smooth muscle-like cells that provide contractile forces to push a mature oocyte into the spermatheca for fertilization. Although several genes that regulate sheath contraction have been characterized, basic components of the contractile apparatuses of the myoepithelial sheath have not been extensively studied. We identified major structural proteins of the contractile apparatuses of the myoepithelial sheath and characterized their nonstriated arrangement. Of interest, integrin and perlecan were found only at the dense bodies, whereas they localized to both dense bodies and M-lines in the striated body wall muscle. RNA interference of most of the myofibrillar components impaired ovulation in a soma-specific manner. Our results provide basic information that helps understanding the mechanism of sheath contraction during ovulation and establishing a new model to study morphogenesis of nonstriated muscle.
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Affiliation(s)
| | | | - Shoichiro Ono
- Correspondence to: Shoichiro Ono, Department of Pathology, Emory University, 615 Michael Street, Whitehead Research Building, Room 105N, Atlanta, GA 30322. E-mail:
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Mariol MC, Martin E, Chambonnier L, Ségalat L. Dystrophin-dependent muscle degeneration requires a fully functional contractile machinery to occur in C. elegans. Neuromuscul Disord 2006; 17:56-60. [PMID: 17134897 DOI: 10.1016/j.nmd.2006.09.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 09/13/2006] [Accepted: 09/18/2006] [Indexed: 11/19/2022]
Abstract
In mammals, the lack of dystrophin leads to a degeneration of skeletal muscles. It has been known for many years that this pathology can be blocked by denervation or immobilization of muscles. It is not yet clear, however, whether this suppressing effect is due to the absence of fiber contraction per se, or to other mechanisms which may be induced by such treatments. We took advantage of the genetic tools available in the animal model Caenorhabditis elegans to address this question. Using RNA interference and existing mutants, we genetically impaired the excitation-contraction cascade at specific points in a dystrophin-deficient C. elegans strain which normally undergoes extensive muscle degeneration. Our data show that reducing sarcomere contraction by slightly impairing the contraction machinery is sufficient to dramatically suppress muscle degeneration. Thus, it is the physical tension exerted on the muscle fibers which is the key deleterious event in the absence of dystrophin.
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24
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Chen KY, Pan H, Lin MJ, Li YY, Wang LC, Wu YC, Hsiao KM. Length-dependent toxicity of untranslated CUG repeats on Caenorhabditis elegans. Biochem Biophys Res Commun 2006; 352:774-9. [PMID: 17150182 DOI: 10.1016/j.bbrc.2006.11.102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
Expansion of CTG repeat within the 3'-untranslated region of the DMPK gene causes the most common neuromuscular disorder, myotonic dystrophy type 1 (DM1), through a RNA trans-dominant mechanism. Here, we explore Caenorhabditis elegans as a model system to investigate the repeat size-dependent toxic effect by expression of green fluorescent protein (GFP) transcripts with various lengths of untranslatable CUG repeats (CUG5, CUG30, CUG83, CUG125, and CUG213) in body wall muscles. CUG213 animals died during embryogenesis or showed retarded growth at larval stages due to defective muscle development. CUG125 animals, although can produce offspring, exhibited uncoordinated muscle function, deviated electropharyngeogram, and an age-dependent abnormality in muscle structure. Most CUG83 animals had normal muscle structure and function as those expressing 30 and shorter repeats. Our results demonstrate for the first time that the in vivo toxicity of CUG repeats is repeat length- and growth-regulated and suggest that expanded CUG repeats are sufficient to cause congenital-like phenotypes in living organisms.
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Affiliation(s)
- Kuan-Yu Chen
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan, ROC
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25
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Carre-Pierrat M, Mariol MC, Chambonnier L, Laugraud A, Heskia F, Giacomotto J, Ségalat L. Blocking of striated muscle degeneration by serotonin in C. elegans. J Muscle Res Cell Motil 2006; 27:253-8. [PMID: 16791712 DOI: 10.1007/s10974-006-9070-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 04/30/2006] [Indexed: 12/31/2022]
Abstract
Prevention of muscle fiber degeneration is a key issue in the treatment of muscular dystrophies such as Duchenne Muscular Dystrophy (DMD). It is widely postulated that existing pharmaceutical compounds might potentially be beneficial to DMD patients, but tools to identify them are lacking. Here, by using a Caenorhabditis elegans model of dystrophin-dependent muscular dystrophy, we show that the neurohormone serotonin and some of its agonists are potent suppressors of muscle degeneration. Inhibitors of serotonin reuptake transporters, which prolong the action of endogenous serotonin, have a similar effect. Moreover, reduction of serotonin levels leads to degeneration of non-dystrophic muscles. Our results demonstrate that serotonin is critical to C. elegans striated muscles. These findings reveal a new function of serotonin in striated muscles.
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Affiliation(s)
- Maité Carre-Pierrat
- CGMC, CNRS-UMR 5534, Université Lyon 1, 43 bld du 11 Novembre, 69622 Villeurbanne Cedex, France
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26
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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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27
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Willis JH, Munro E, Lyczak R, Bowerman B. Conditional dominant mutations in the Caenorhabditis elegans gene act-2 identify cytoplasmic and muscle roles for a redundant actin isoform. Mol Biol Cell 2006; 17:1051-64. [PMID: 16407404 PMCID: PMC1382297 DOI: 10.1091/mbc.e05-09-0886] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Animal genomes each encode multiple highly conserved actin isoforms that polymerize to form the microfilament cytoskeleton. Previous studies of vertebrates and invertebrates have shown that many actin isoforms are restricted to either nonmuscle (cytoplasmic) functions, or to myofibril force generation in muscle cells. We have identified two temperature-sensitive and semidominant embryonic-lethal Caenorhabditis elegans mutants, each with a single mis-sense mutation in act-2, one of five C. elegans genes that encode actin isoforms. These mutations alter conserved and adjacent amino acids predicted to form part of the ATP binding pocket of actin. At the restrictive temperature, both mutations resulted in aberrant distributions of cortical microfilaments associated with abnormal and striking membrane ingressions and protrusions. In contrast to the defects caused by these dominant mis-sense mutations, an act-2 deletion did not result in early embryonic cell division defects, suggesting that additional and redundant actin isoforms are involved. Accordingly, we found that two additional actin isoforms, act-1 and act-3, were required redundantly with act-2 for cytoplasmic function in early embryonic cells. The act-1 and -3 genes also have been implicated previously in muscle function. We found that an ACT-2::GFP reporter was expressed cytoplasmically in embryonic cells and also was incorporated into contractile filaments in adult muscle cells. Furthermore, one of the dominant act-2 mutations resulted in uncoordinated adult movement. We conclude that redundant C. elegans actin isoforms function in both muscle and nonmuscle contractile processes.
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Affiliation(s)
- John H Willis
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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28
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Abstract
This is the first of a projected series of canonic reviews covering all invertebrate muscle literature prior to 2005 and covers muscle genes and proteins except those involved in excitation-contraction coupling (e.g., the ryanodine receptor) and those forming ligand- and voltage-dependent channels. Two themes are of primary importance. The first is the evolutionary antiquity of muscle proteins. Actin, myosin, and tropomyosin (at least, the presence of other muscle proteins in these organisms has not been examined) exist in muscle-like cells in Radiata, and almost all muscle proteins are present across Bilateria, implying that the first Bilaterian had a complete, or near-complete, complement of present-day muscle proteins. The second is the extraordinary diversity of protein isoforms and genetic mechanisms for producing them. This rich diversity suggests that studying invertebrate muscle proteins and genes can be usefully applied to resolve phylogenetic relationships and to understand protein assembly coevolution. Fully achieving these goals, however, will require examination of a much broader range of species than has been heretofore performed.
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Affiliation(s)
- Scott L Hooper
- Neuroscience Program, Department of Biological Sciences, Irvine Hall, Ohio University, Athens, Ohio 45701, USA.
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29
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Abstract
In several types of animals, muscle cells use membrane extensions to contact motor axons during development. To better understand the process of membrane extension in muscle cells, we investigated the development of Caenorhabditis elegans muscle arms, which extend to motor axons and form the postsynaptic element of the neuromuscular junction. We found that muscle arm development is a highly regulated process: the number of muscle arms extended by each muscle, the shape of the muscle arms and the path taken by the muscle arms to reach the motor axons are largely stereotypical. We also investigated the role of several cytoskeletal components and regulators during arm development, and found that tropomyosin (LEV-11), the actin depolymerizing activity of ADF/cofilin (UNC-60B) and, surprisingly, myosin heavy chain B (UNC-54) are each required for muscle arm extension. This is the first evidence that UNC-54, which is found in thick filaments of sarcomeres, can also play a role in membrane extension. The muscle arm phenotypes produced when these genes are mutated support a 'two-phase' model that distinguishes passive muscle arm development in embryogenesis from active muscle arm extension during larval development.
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Affiliation(s)
- Scott J Dixon
- Department of Medical Genetics and Microbiology, Collaborative Program in Developmental Biology, University of Toronto, Toronto, ON, M5S 1A8, Canada
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30
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MacQueen AJ, Baggett JJ, Perumov N, Bauer RA, Januszewski T, Schriefer L, Waddle JA. ACT-5 is an essential Caenorhabditis elegans actin required for intestinal microvilli formation. Mol Biol Cell 2005; 16:3247-59. [PMID: 15872090 PMCID: PMC1165408 DOI: 10.1091/mbc.e04-12-1061] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Investigation of Caenorhabditis elegans act-5 gene function revealed that intestinal microvillus formation requires a specific actin isoform. ACT-5 is the most diverged of the five C. elegans actins, sharing only 93% identity with the other four. Green fluorescent protein reporter and immunofluorescence analysis indicated that act-5 gene expression is limited to microvillus-containing cells within the intestine and excretory systems and that ACT-5 is apically localized within intestinal cells. Animals heterozygous for a dominant act-5 mutation looked clear and thin and grew slowly. Animals homozygous for either the dominant act-5 mutation, or a recessive loss of function mutant, exhibited normal morphology and intestinal cell polarity, but died during the first larval stage. Ultrastructural analysis revealed a complete loss of intestinal microvilli in homozygous act-5 mutants. Forced expression of ACT-1 under the control of the act-5 promoter did not rescue the lethality of the act-5 mutant. Together with immuno-electron microscopy experiments that indicated ACT-5 is enriched within microvilli themselves, these results suggest a microvillus-specific function for act-5, and further, they raise the possibility that specific actins may be specialized for building microvilli and related structures.
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Affiliation(s)
- A J MacQueen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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31
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Kim H, Rogers MJ, Richmond JE, McIntire SL. SNF-6 is an acetylcholine transporter interacting with the dystrophin complex in Caenorhabditis elegans. Nature 2004; 430:891-6. [PMID: 15318222 DOI: 10.1038/nature02798] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 07/02/2004] [Indexed: 11/08/2022]
Abstract
Muscular dystrophies are among the most common human genetic diseases and are characterized by progressive muscle degeneration. Muscular dystrophies result from genetic defects in components of the dystrophin-glycoprotein complex (DGC), a multimeric complex found in the muscle cell plasma membrane. The DGC links the intracellular cytoskeleton to the extracellular matrix and is thought to be important for maintaining the mechanical integrity of muscles and organizing signalling molecules. The exact role of the DGC in the pathogenesis of disease has, however, remained uncertain. Mutations in Caenorhabditis elegans DGC genes lead to specific defects in coordinated movement and can also cause muscle degeneration. Here we show that mutations in the gene snf-6 result in phenotypes indistinguishable from those of the DGC mutants, and that snf-6 encodes a novel acetylcholine/choline transporter. SNF-6 mediates the uptake of acetylcholine at neuromuscular junctions during periods of increased synaptic activity. SNF-6 also interacts with the DGC, and mutations in DGC genes cause a loss of SNF-6 at neuromuscular junctions. Improper clearing of acetylcholine and prolonged excitation of muscles might contribute to the pathogenesis of muscular dystrophies.
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Affiliation(s)
- Hongkyun Kim
- Ernest Gallo Clinic and Research Center, Programs in Neuroscience and Biomedical Sciences, Department of Neurology, University of California at San Francisco, 5858 Horton Street, Suite 200, Emeryville, California 94608, USA
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32
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Gaud A, Simon JM, Witzel T, Carre-Pierrat M, Wermuth CG, Ségalat L. Prednisone reduces muscle degeneration in dystrophin-deficient Caenorhabditis elegans. Neuromuscul Disord 2004; 14:365-70. [PMID: 15145337 DOI: 10.1016/j.nmd.2004.02.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Revised: 02/12/2004] [Accepted: 02/20/2004] [Indexed: 11/24/2022]
Abstract
Duchenne muscular dystrophy is a degenerative muscular disease caused by mutations in the dystrophin gene. There is no curative treatment against Duchenne muscular dystrophy. In several countries, the steroid prednisone (or analogs) is prescribed as a palliative treatment. In the model animal Caenorhabditis elegans, mutations of the dys-1 dystrophin-like gene lead to a muscular degenerative phenotype when they are associated with a mild MyoD mutation. This cheap and fast-growing model of dystrophinopathy may be used to screen for molecules able to slow muscle degeneration. In a blind screen of approximately 100 compounds covering a wide spectrum of targets, we found that prednisone is beneficial to the C. elegans dystrophin-deficient muscles. Prednisone reduces by 40% the number of degenerating cells in this animal. This result is a proof-of-principle for the use of C. elegans as a tool in the search for molecules active against the effects of dystrophin-deficiency. Moreover, since C. elegans is not susceptible to inflammation, this suggests that prednisone exerts a direct effect on muscle survival.
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Affiliation(s)
- Aurélie Gaud
- CGMC, CNRS-UMR 5534, Université Lyon1, 43 bld du 11 Novembre, 69622 Villeurbanne cedex, France
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33
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Grisoni K, Gieseler K, Mariol MC, Martin E, Carre-Pierrat M, Moulder G, Barstead R, Ségalat L. The stn-1 syntrophin gene of C.elegans is functionally related to dystrophin and dystrobrevin. J Mol Biol 2003; 332:1037-46. [PMID: 14499607 DOI: 10.1016/j.jmb.2003.08.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Syntrophins are a family of PDZ domain-containing adaptor proteins required for receptor localization. Syntrophins are also associated with the dystrophin complex in muscles. We report here the molecular and functional characterization of the Caenorhabditis elegans gene stn-1 (F30A10.8), which encodes a syntrophin with homology to vertebrate alpha and beta-syntrophins. stn-1 is expressed in neurons and in muscles of C.elegans. stn-1 mutants resemble dystrophin (dys-1) and dystrobrevin (dyb-1) mutants: they are hyperactive, bend their heads when they move forward, tend to hypercontract, and are hypersensitive to the acetylcholinesterase inhibitor aldicarb. These phenotypes are suppressed when stn-1 is expressed under the control of a muscular promoter, indicating that they are caused by the absence of stn-1 in muscles. These results suggest that the role of syntrophin is linked to dystrophin function in C.elegans.
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Affiliation(s)
- Karine Grisoni
- CGMC, CNRS-UMR 5534, Université Lyon-1, 43 Bid du 11 Novembre, 69622, Villeurbanne, cedex, France.
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34
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Gilliland LU, Pawloski LC, Kandasamy MK, Meagher RB. Arabidopsis actin gene ACT7 plays an essential role in germination and root growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 33:319-28. [PMID: 12535345 DOI: 10.1046/j.1365-313x.2003.01626.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Arabidopsis contains eight actin genes. Of these ACT7 is the most strongly expressed in young plant tissues and shows the greatest response to physiological cues. Adult plants homozygous for the act7 mutant alleles show no obvious above-ground phenotypes, which suggests a high degree of functional redundancy among plant actins. However, act7-1 mutant plants are at a strong selective disadvantage when grown in competition with wild-type plants and therefore must have undetected physical defects. The act7-1 and act7-4 alleles contain T-DNA insertions just after the stop codon and within the first intron, respectively. Homozygous mutant seedlings of both alleles showed less than 7% of normal ACT7 protein levels. Mutants displayed delayed and less efficient germination, increased root twisting and waving, and retarded root growth. The act7-4 mutant showed the most dramatic reduction in root growth. The act7-4 root apical cells were not in straight files and contained oblique junctions between cells suggesting a possible role for ACT7 in determining cell polarity. Wild-type root growth was fully restored to the act7-1 mutant by the addition of an exogenous copy of the ACT7 gene. T-DNA insertions just downstream of the major polyadenylation sites (act7-2, act7-3) appeared fully wild type. The act7 mutant phenotypes demonstrate a significant requirement for functional ACT7 protein during root development and explain the strong negative selection component seen for the act7-1 mutant.
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Affiliation(s)
- Laura U Gilliland
- Department of Biochemistry, 215 Biochemistry Building, Michigan State University, East Lansing, MI 48824, USA
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35
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Gieseler K, Grisoni K, Mariol MC, Ségalat L. Overexpression of dystrobrevin delays locomotion defects and muscle degeneration in a dystrophin-deficient Caenorhabditis elegans. Neuromuscul Disord 2002; 12:371-7. [PMID: 12062255 DOI: 10.1016/s0960-8966(01)00330-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Duchenne muscular dystrophy is one of the most common neuromuscular diseases. It is caused by mutations in the dystrophin gene. Dystrobrevins are dystrophin-associated proteins potentially involved in signal transduction. The nematode Caenorhabditis elegans possesses one dystrophin-like (dys-1) and one dystrobrevin-like (dyb-1) gene. Mutations of dyb-1 and dys-1 lead to similar phenotypes, comprising hyperactivity and a tendency to hypercontract, which suggest that these proteins may participate in a common function. We show here that overexpression of the Dyb-1 protein delays the onset of the myopathy observed in the C. elegans double mutant (dys-1; hlh-1 mutations). This finding indicates that, in C. elegans, (1) the absence of dystrophin can be partly compensated for by extra doses of dystrobrevin, and (2) dystrobrevin is partly functional in absence of dystrophin.
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Affiliation(s)
- Kathrin Gieseler
- CGMC, CNRS-UMR 5534, Université Lyon 1, 43 bld du 11 Novembre, 69622, Villeurbanne cedex, France
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36
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Gieseler K, Mariol MC, Bessou C, Migaud M, Franks CJ, Holden-Dye L, Ségalat L. Molecular, genetic and physiological characterisation of dystrobrevin-like (dyb-1) mutants of Caenorhabditis elegans. J Mol Biol 2001; 307:107-17. [PMID: 11243807 DOI: 10.1006/jmbi.2000.4480] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dystrobrevins are protein components of the dystrophin complex, whose disruption leads to Duchenne muscular dystrophy and related diseases. The Caenorhabditis elegans dystrobrevin gene (dyb-1) encodes a protein 38 % identical with its mammalian counterparts. The C. elegans dystrobrevin is expressed in muscles and neurons. We characterised C. elegans dyb-1 mutants and showed that: (1) their behavioural phenotype resembles that of dystrophin (dys-1) mutants; (2) the phenotype of dyb-1 dys-1 double mutants is not different from the single ones; (3) dyb-1 mutants are more sensitive than wild-type animals to reductions of acetylcholinesterase levels and have an increased response to acetylcholine; (4) dyb-1 mutations alone do not lead to muscle degeneration, but synergistically produce a progressive myopathy when combined with a mild MyoD/hlh-1 mutation. All together, these findings further substantiate the role of dystrobrevins in cholinergic transmission and as functional partners of dystrophin.
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Affiliation(s)
- K Gieseler
- CGMC, CNRS-UMR 5534, Université Lyon1, 43 bld du 11 Novembre, 69622 Villeurbanne cedex, France
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37
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Piano F, Schetter AJ, Mangone M, Stein L, Kemphues KJ. RNAi analysis of genes expressed in the ovary of Caenorhabditis elegans. Curr Biol 2000; 10:1619-22. [PMID: 11137018 DOI: 10.1016/s0960-9822(00)00869-1] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As a step towards comprehensive functional analysis of genomes, systematic gene knockout projects have been initiated in several organisms [1]. In metazoans like C. elegans, however, maternal contribution can mask the effects of gene knockouts on embryogenesis. RNA interference (RNAi) provides an alternative rapid approach to obtain loss-of-function information that can also reveal embryonic roles for the genes targeted [2,3]. We have used RNAi to analyze a random set of ovarian transcripts and have identified 81 genes with essential roles in embryogenesis. Surprisingly, none of them maps on the X chromosome. Of these 81 genes, 68 showed defects before the eight-cell stage and could be grouped into ten phenotypic classes. To archive and distribute these data we have developed a database system directly linked to the C. elegans database (Wormbase). We conclude that screening cDNA libraries by RNAi is an efficient way of obtaining in vivo function for a large group of genes. Furthermore, this approach is directly applicable to other organisms sensitive to RNAi and whose genomes have not yet been sequenced.
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Affiliation(s)
- F Piano
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
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38
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Gieseler K, Grisoni K, Ségalat L. Genetic suppression of phenotypes arising from mutations in dystrophin-related genes in Caenorhabditis elegans. Curr Biol 2000; 10:1092-7. [PMID: 10996789 DOI: 10.1016/s0960-9822(00)00691-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Dystrophin is the product of the gene that is mutated in Duchenne muscular dystrophy (DMD), a progressive neuromuscular disease for which no treatment is available. Mice carrying a mutation in the gene for dystrophin (mdx mice) display only a mild phenotype, but it is aggravated when combined with a mutation in the MyoD gene. The nematode worm Caenorhabditis elegans has a dystrophin homologue (dys-1), but null mutations in dys-1 do not result in muscle degeneration. RESULTS We generated worms carrying both the dys-1 null mutation cx18, and a weak mutation, cc561ts, of the C. elegans MyoD homologue hlh-1. The double mutants displayed a time-dependent impairment of locomotion and egg laying, a phenotype not seen in the single mutants, and extensive muscle degeneration. This result allowed us to look for genes that, when misexpressed, could suppress the dys-1; hlh-1 phenotype. When overexpressed, the dyc-1 gene - whose loss-of-function phenotype resembles that of dys-1 - partially suppressed the dys-1; hlh-1 phenotype. The dyc-1 gene encodes a novel protein sharing similarities with the mammalian neural nitric oxide synthase (nNOS)-binding protein CAPON, and is expressed in the muscles of the worm. CONCLUSIONS As a C. elegans model for dystrophin-dependent myopathy, the dys-1; hlh-1 worms should permit the identification of genes, and ultimately drugs, that would reverse the muscle degeneration in this model.
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Affiliation(s)
- K Gieseler
- CGMC, CNRS-UMR5534, Université Lyon-1, 43 boulevard du 11 Novembre, 69622, Villeurbanne cedex, France
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39
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Ono S. Purification and biochemical characterization of actin from Caenorhabditis elegans: its difference from rabbit muscle actin in the interaction with nematode ADF/cofilin. CELL MOTILITY AND THE CYTOSKELETON 2000; 43:128-36. [PMID: 10379837 DOI: 10.1002/(sici)1097-0169(1999)43:2<128::aid-cm4>3.0.co;2-c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biochemical analysis of cytoskeletal proteins of the nematode Caenorhabditis elegans can be combined with a vast resource of genetic information in order to understand the regulation and function of the cytoskeleton in vivo. Here, I report an improved and efficient method to purify actin from wild-type C. elegans and characterization of its biochemical properties. The purified actin was highly pure and free of several known actin-binding proteins. G-actin was polymerized into F-actin in a similar kinetic process to rabbit muscle actin. G-actin interacted with bovine DNase I and inhibited its activity. However, UNC-60B, an isoform of ADF/cofilin in C. elegans, showed a marked depolymerizing activity on C. elegans actin but not on rabbit muscle actin. The results indicate that C. elegans actin shares common biochemical properties with rabbit muscle actin, while actin-binding proteins can interact with C. elegans actin in a distinct manner from rabbit muscle actin.
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Affiliation(s)
- S Ono
- Department of Pathology, Emory University, Atlanta, Georgia 30322, USA.
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40
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Frieden C, Du J, Schriefer L, Buzan J. Purification and polymerization properties of two lethal yeast actin mutants. Biochem Biophys Res Commun 2000; 271:464-8. [PMID: 10799320 DOI: 10.1006/bbrc.2000.2650] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The budding yeast Saccharomyces cerevisiae contains a single actin gene and the gene product, actin, is essential for growth. Two mutants of yeast actin that do not support yeast growth were prepared from yeast by coexpressing the mutant and a 6-histidine-tagged wild-type actin followed by separation of the wild-type and mutant actin using Ni-NTA chromatography as described elsewhere [Buzan, J., Du, J., Karpova, T., and Frieden, C. (1999) Proc. Natl. Acad. Sci. USA 96, 2823-2827]. The mutations, in muscle actin numbering, were at positions 334 (Glu334Lys) and 168 (Gly168Arg) and were chosen based on phenotypic changes observed in the behavior of actin mutants of Caenorhabditis elegans. Glu334 is located on the surface of actin between subdomains 1 and 3 while Gly168 is located in a region near actin-actin contacts in the actin filament. The Glu334Lys mutant polymerized slightly faster than wild-type yeast actin, suggesting that loss of interactions with some actin binding protein, rather than loss of actin-actin contacts, was responsible for its inability to support yeast growth. The Gly168Arg mutant polymerized at a rate similar to wild-type but the extent was considerably less, kinetic characteristics suggesting a high critical concentration (ca. 4 microM) without a large change in the ability to form nuclei for the nucleation-elongation process.
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Affiliation(s)
- C Frieden
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
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41
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Lee LC, Hunter JJ, Mujeeb A, Turck C, Parslow TG. Evidence for alpha-helical conformation of an essential N-terminal region in the human Bcl2 protein. J Biol Chem 1996; 271:23284-8. [PMID: 8798527 DOI: 10.1074/jbc.271.38.23284] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A region occupying approximately 24 amino acids near the N terminus of human Bcl2 is essential for this cytoplasmic membrane protein's ability to inhibit apoptosis. Systematic mutagenesis of this N-terminal region indicates that only five hydrophobic and aromatic residues within it are specifically required for function. Computerized secondary structure prediction, together with circular dichroism spectroscopy of synthetic peptides, indicates that the region encompassing these five residues has the propensity to take on an alpha-helical conformation in the presence of SDS micelles, which presumably mimic the hydrophobic surfaces of cellular membranes or polypeptides. The five critical residues are predicted to be clustered on one face of this putative helix, where they might serve to mediate protein-protein contacts involved in the multimerization of Bcl2 or in the interaction of Bcl2 with other, as yet unidentified components of the apoptotic pathway. Apparent structural homologues of this helical motif are also present in at least some other anti-apoptotic proteins from the Bcl2 family but not in those family members that tend to potentiate, rather than inhibit, apoptosis.
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Affiliation(s)
- L C Lee
- Department of Pathology, University of California, San Francisco, California 94143, USA
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42
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Goetinck S, Waterston RH. The Caenorhabditis elegans muscle-affecting gene unc-87 encodes a novel thin filament-associated protein. J Cell Biol 1994; 127:79-93. [PMID: 7929573 PMCID: PMC2120179 DOI: 10.1083/jcb.127.1.79] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mutations in the unc-87 gene of Caenorhabditis elegans affect the structure and function of bodywall muscle, resulting in variable paralysis. We cloned the unc-87 gene by taking advantage of a transposon-induced allele of unc-87 and the correspondence of the genetic and physical maps in C. elegans. A genomic clone was isolated that alleviates the mutant phenotype when introduced into unc-87 mutants. Sequence analysis of a corresponding cDNA clone predicts a 357-amino acid, 40-kD protein that is similar to portions of the vertebrate smooth muscle proteins calponin and SM22 alpha, the Drosophila muscle protein mp20, the deduced product of the C. elegans cDNA cm7g3, and the rat neuronal protein np25. Analysis of the genomic sequence and of various transcripts represented in a cDNA library suggest that unc-87 mRNAs are subject to alternative splicing. Immunohistochemistry of wildtype and mutant animals with antibodies to an unc-87 fusion protein indicates that the gene product is localized to the I-band of bodywall muscle. Studies of the UNC-87 protein in other muscle mutants suggest that the unc-87 gene product associates with thin filaments, in a manner that does not depend on the presence of the thin filament protein tropomyosin.
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Affiliation(s)
- S Goetinck
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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43
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Goetinck S, Waterston RH. The Caenorhabditis elegans UNC-87 protein is essential for maintenance, but not assembly, of bodywall muscle. J Cell Biol 1994; 127:71-8. [PMID: 7929572 PMCID: PMC2120180 DOI: 10.1083/jcb.127.1.71] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mutations in the unc-87 gene of Caenorhabditis elegans cause disorganization of the myofilament lattice in adult bodywall muscle. In order to assess the organization of specific bodywall muscle components in the absence of the unc-87 gene product, we examined the bodywall muscles of mutant animals using phalloidin and monoclonal antibodies to various muscle proteins. These studies indicated that the bodywall muscle of unc-87 embryos is initially almost wild type in its organization, but at later stages, the muscle becomes severely disorganized. To address the possibility that this disorganization is due to deterioration of the muscle as a result of contraction, we introduced into the unc-87 mutant background a mutation that decreases myosin heavy chain activity but does not substantially affect muscle structure. The improved muscle structure and motility of the double mutants are consistent with the hypothesis that at least part of the disorganization phenotype of unc-87 mutants is a consequence of the wild-type levels of force generated during muscle contraction. These results imply that the role of the unc-87 gene product is not in specifying organization but rather in serving as a structural component maintaining lattice integrity during and after contraction.
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Affiliation(s)
- S Goetinck
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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44
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Savage C, Xue Y, Mitani S, Hall D, Zakhary R, Chalfie M. Mutations in the Caenorhabditis elegans beta-tubulin gene mec-7: effects on microtubule assembly and stability and on tubulin autoregulation. J Cell Sci 1994; 107 ( Pt 8):2165-75. [PMID: 7983175 DOI: 10.1242/jcs.107.8.2165] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have sequenced 45 mutations in mec-7, a beta-tubulin gene required for the production of 15-protofilament microtubules in the nematode Caenorhabditis elegans, and have correlated sequence alterations with mutant phenotypes. The expression patterns of most alleles have also been determined by in situ hybridization and immunocytochemistry. Most (12/16) complete loss-of-function alleles, which are recessive, result from nonsense mutations, insertions, or deletions; three others disrupt a putative GTP-binding domain. Three of the four loss-of-function, missense mutations result in elevated mec-7 message levels, suggesting a defect in tubulin autoregulation that may be attributable to a loss in the ability to form heterodimers. Most (8/9) mild alleles are caused by missense mutations. Two mild alleles appear to increase microtubule stability and lead to the elaboration of ectopic neuronal processes in mec-7-expressing cells. Most (15/23) mutations that cause severe dominant or semidominant phenotypes are clustered into three discrete domains; four others occur in putative GTP-binding regions. Many of these dominant mutations appear to completely disrupt microtubule assembly.
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Affiliation(s)
- C Savage
- Department of Biological Sciences, Sherman Fairchild Center, Columbia University, New York, NY 10027
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45
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Williams BD, Waterston RH. Genes critical for muscle development and function in Caenorhabditis elegans identified through lethal mutations. J Biophys Biochem Cytol 1994; 124:475-90. [PMID: 8106547 PMCID: PMC2119919 DOI: 10.1083/jcb.124.4.475] [Citation(s) in RCA: 277] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
By taking advantage of a lethal phenotype characteristic of Caenorhabditis elegans embryos that fail to move, we have identified 13 genes required for muscle assembly and function and discovered a new lethal class of alleles for three previously known muscle-affecting genes. By staining mutant embryos for myosin and actin we have recognized five distinct classes of genes: mutations in four genes disrupt the assembly of thick and thin filaments into the myofilament lattice as well as the polarized location of these components to the sarcolemma. Mutations in another three genes also disrupt thick and thin filament assembly, but allow proper polarization of lattice components based on the myosin heavy chain isoform that we analyzed. Another two classes of genes are defined by mutations with principal effects on thick or thin filament assembly into the lattice, but not both. The final class includes three genes in which mutations cause relatively minor defects in lattice assembly. Failure of certain mutants to stain with antibodies to specific muscle cell antigens suggest that two genes associated with severe disruptions of myofilament lattice assembly may code for components of the basement membrane and the sarcolemma that are concentrated where dense bodies (Z-line analogs) and M-lines attach to the cell membrane. Similar evidence suggests that one of the genes associated with mild effects on lattice assembly may code for tropomyosin. Many of the newly identified genes are likely to play critical roles in muscle development and function.
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Affiliation(s)
- B D Williams
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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Hresko MC, Williams BD, Waterston RH. Assembly of body wall muscle and muscle cell attachment structures in Caenorhabditis elegans. J Biophys Biochem Cytol 1994; 124:491-506. [PMID: 8106548 PMCID: PMC2119906 DOI: 10.1083/jcb.124.4.491] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
C. Elegans has four muscle quadrants that are used for locomotion. Contraction is converted to locomotion because muscle cells are anchored to the cuticle (the outer covering of the worm) by a specialized basement membrane and hemidesmosome structures in the hypodermis (a cellular syncytium that covers the worm and secretes the cuticle). To study muscle assembly, we have used antibodies to determine the spatial and temporal distribution of muscle and attachment structure components in wild-type and mutant C. elegans embryos. Myofibrillar components are first observed diffusely distributed in the muscle cells, and are expressed in some dividing cells. Later, the components accumulate at the membrane adjacent to the hypodermis where the sarcomeres will form, showing that the cells have become polarized. Assembly of muscle attachment structures is spatially and temporally coordinated with muscle assembly suggesting that important developmental signals may be passed between muscle and hypodermal cells. Analysis of embryos homozygous for mutations that affect muscle assembly show that muscle components closer to the membrane than the affected protein assemble quite well, while those further from the membrane do not. Our results suggest a model where lattice assembly is initiated at the membrane and the spatial organization of the structural elements of the muscle is dictated by membrane proximal events, not by the filament components themselves.
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Affiliation(s)
- M C Hresko
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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McKim KS, Matheson C, Marra MA, Wakarchuk MF, Baillie DL. The Caenorhabditis elegans unc-60 gene encodes proteins homologous to a family of actin-binding proteins. MOLECULAR & GENERAL GENETICS : MGG 1994; 242:346-57. [PMID: 8107682 DOI: 10.1007/bf00280425] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mutations in the unc-60 gene of the nematode Caenorhabditis elegans result in paralysis. The thin filaments of the muscle cells are severely disorganized and not bundled with myosin into functional contractile units. Here we report the cloning and sequence of unc-60. Two unc-60 transcripts, 1.3 and 0.7 kb in size, were detected. The transcripts share a single exon encoding only the initial methionine, yet encode proteins with homologous sequences. The predicted protein products are 165 and 152 amino acids in length and their sequences are 38% identical. Both proteins are homologous to a family of actin depolymerizing proteins identified in vertebrate, plant and protozoan systems. We propose that the unc-60 locus encodes proteins that depolymerize growing actin filaments in muscle cells, and that these proteins are required for the assembly of actin filaments into the contractile myofilament lattice of C. elegans muscle. unc-60 has an essential function in development, since one unc-60 allele, s1586, has a recessive lethal phenotype. Our characterization of s1586 has shown that it is a small deletion which disrupts both coding regions.
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Affiliation(s)
- K S McKim
- Department of Biological Sciences, Simon Fraser University, Burnaby, B.C. Canada
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Abstract
The analysis of both naturally occurring and experimentally induced mutants has greatly advanced our understanding of muscle development. Molecular biological techniques have led to the isolation of genes associated with inherited human diseases that affect muscle tissues. Analysis of the encoded proteins in conjunction with the mutant phenotypes can provide powerful insights into the function of the protein in normal muscle development. Systematic searches for muscle mutations have been made in experimental systems, most notably the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans. In addition, known muscle protein genes from other organisms have been used to isolate homologs from genetically manipulatable organisms, allowing mutant analysis and the study of protein function in vivo. Mutations in transcription factor genes that affect mesoderm development have been isolated and genetic lesions affecting myofibril assembly have been identified. Genetic experiments inducing mutations and rescuing them by transgenic methods have uncovered functions of myofibrillar protein isoforms. Some isoforms perform muscle-specific functions, whereas others appear to be replaceable by alternative isoforms. Mutant analysis has also uncovered a relationship between proteins at the cell membrane and the assembly and alignment of the myofibrillar apparatus. We discuss examples of each of these genetic approaches as well as the developmental and evolutionary implications of the results.
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Affiliation(s)
- H F Epstein
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
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Feinberg MB, Trono D. Intracellular immunization: trans-dominant mutants of HIV gene products as tools for the study and interruption of viral replication. AIDS Res Hum Retroviruses 1992; 8:1013-22. [PMID: 1503816 DOI: 10.1089/aid.1992.8.1013] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- M B Feinberg
- Department of Medicine, University of California, San Francisco
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Levin JZ, Horvitz HR. The Caenorhabditis elegans unc-93 gene encodes a putative transmembrane protein that regulates muscle contraction. J Biophys Biochem Cytol 1992; 117:143-55. [PMID: 1313436 PMCID: PMC2289394 DOI: 10.1083/jcb.117.1.143] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
unc-93 is one of a set of five interacting genes involved in the regulation or coordination of muscle contraction in Caenorhabditis elegans. Rare altered-function alleles of unc-93 result in sluggish movement and a characteristic "rubber band" uncoordinated phenotype. By contrast, null alleles cause no visibly abnormal phenotype, presumably as a consequence of the functional redundancy of unc-93. To understand better the role of unc-93 in regulating muscle contraction, we have cloned and molecularly characterized this gene. We isolated transposon-insertion alleles and used them to identify the region of DNA encoding the unc-93 protein. Two unc-93 proteins differing at their NH2 termini are potentially encoded by transcripts that differ at their 5' ends. The putative unc-93 proteins are 700 and 705 amino acids in length and have two distinct regions: the NH2 terminal portion of 240 or 245 amino acids is extremely hydrophilic, whereas the rest of the protein has multiple potential membrane-spanning domains. The unc-93 transcripts are low in abundance and the unc-93 gene displays weak codon usage bias, suggesting that the unc-93 protein is relatively rare. The unc-93 protein has no sequence similarity to proteins listed in current data-bases. Thus, unc-93 is likely to encode a novel membrane-associated muscle protein. We discuss possible roles for the unc-93 protein either as a component of an ion transport system involved in excitation-contraction coupling in muscle or in coordinating muscle contraction between muscle cells by affecting the functioning of gap junctions.
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Affiliation(s)
- J Z Levin
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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