1
|
Chomphoo S, Sakagami H, Kondo H, Hipkaeo W. Localization of EFA6A, an exchange factor for Arf6, in Z-lines and sarcoplasmic reticulum membranes in addition to myofilaments in I-domains of skeletal myofibers of peri-natal mice. Acta Histochem 2024; 126:152187. [PMID: 39126836 DOI: 10.1016/j.acthis.2024.152187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 08/12/2024]
Abstract
Membrane trafficking and actin-remodeling are critical for well-maintained integrity of the cell organization and activity, and they require Arf6 (ADP ribosylation factor 6) activated by GEF (guanine nucleotide exchange factor) including EFA6 (exchange factor for Arf6). In the present immuno-electron microscopic study following previous immunohistochemical study by these authors (Chomphoo et al., 2020) of in situ skeletal myoblasts and myotubes of pre-and perinatal mice, the immunoreactivity for EFA6A was found to be localized at Z-bands and sarcoplasmic reticulum (SR) membranes in I-domains as well as I-domain myofilaments of skeletal myofibers of perinatal mice. Based on the previous finding that EFA6 anchored on the neuronal postsynaptic density via α-actinin which is known to be shared by muscular Z-bands, the present finding suggests that EFA6A is also anchored on Z-bands via α-actinin and involved in the membrane trafficking and actin-remodeling in skeletal myofibers. The localization of EFA6A-immunoreactivity in I-domain SR suggests a differential function in the membrane traffic between the I- and A-domain intracellular membranes in perinatal skeletal myofibers.
Collapse
Affiliation(s)
- Surang Chomphoo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
| | - Hiroyuki Sakagami
- Department of Anatomy, School of Medicine, Kitasato University, Sagamihara, Japan
| | - Hisatake Kondo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; Department of Anatomy, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Wiphawi Hipkaeo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| |
Collapse
|
2
|
Mukhopadhyay U, Mandal T, Chakraborty M, Sinha B. The Plasma Membrane and Mechanoregulation in Cells. ACS OMEGA 2024; 9:21780-21797. [PMID: 38799362 PMCID: PMC11112598 DOI: 10.1021/acsomega.4c01962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 05/29/2024]
Abstract
Cells inhabit a mechanical microenvironment that they continuously sense and adapt to. The plasma membrane (PM), serving as the boundary of the cell, plays a pivotal role in this process of adaptation. In this Review, we begin by examining well-studied processes where mechanoregulation proves significant. Specifically, we highlight examples from the immune system and stem cells, besides discussing processes involving fibroblasts and other cell types. Subsequently, we discuss the common molecular players that facilitate the sensing of the mechanical signal and transform it into a chemical response covering integrins YAP/TAZ and Piezo. We then review how this understanding of molecular elements is leveraged in drug discovery and tissue engineering alongside a discussion of the methodologies used to measure mechanical properties. Focusing on the processes of endocytosis, we discuss how cells may respond to altered membrane mechanics using endo- and exocytosis. Through the process of depleting/adding the membrane area, these could also impact membrane mechanics. We compare pathways from studies illustrating the involvement of endocytosis in mechanoregulation, including clathrin-mediated endocytosis (CME) and the CLIC/GEEC (CG) pathway as central examples. Lastly, we review studies on cell-cell fusion during myogenesis, the mechanical integrity of muscle fibers, and the reported and anticipated roles of various molecular players and processes like endocytosis, thereby emphasizing the significance of mechanoregulation at the PM.
Collapse
Affiliation(s)
- Upasana Mukhopadhyay
- Department of Biological
Sciences, Indian Institute of Science Education
and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Tithi Mandal
- Department of Biological
Sciences, Indian Institute of Science Education
and Research Kolkata, Mohanpur, West Bengal 741246, India
| | | | - Bidisha Sinha
- Department of Biological
Sciences, Indian Institute of Science Education
and Research Kolkata, Mohanpur, West Bengal 741246, India
| |
Collapse
|
3
|
Zhao M, Smith L, Volpatti J, Fabian L, Dowling JJ. Insights into wild-type dynamin 2 and the consequences of DNM2 mutations from transgenic zebrafish. Hum Mol Genet 2020; 28:4186-4196. [PMID: 31691805 DOI: 10.1093/hmg/ddz260] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 09/10/2019] [Accepted: 10/23/2019] [Indexed: 12/15/2022] Open
Abstract
Dynamin 2 (DNM2) encodes a ubiquitously expressed large GTPase with membrane fission capabilities that participates in the endocytosis of clathrin-coated vesicles. Heterozygous mutations in DNM2 are associated with two distinct neuromuscular disorders, Charcot-Marie-Tooth disease (CMT) and autosomal dominant centronuclear myopathy (CNM). Despite extensive investigations in cell culture, the role of dynamin 2 in normal muscle development is poorly understood and the consequences of DNM2 mutations at the molecular level in vivo are not known. To address these gaps in knowledge, we developed transgenic zebrafish expressing either wild-type dynamin 2 or dynamin 2 with either a CNM or CMT mutation. Taking advantage of the live imaging capabilities of the zebrafish embryo, we establish the localization of wild-type and mutant dynamin 2 in vivo, showing for the first time distinctive dynamin 2 subcellular compartments. Additionally, we demonstrate that CNM-related DNM2 mutations are associated with protein mislocalization and aggregation. Lastly, we define core phenotypes associated with our transgenic mutant fish, including impaired motor function and altered muscle ultrastructure, making them the ideal platform for drug screening. Overall, using the power of the zebrafish, we establish novel insights into dynamin 2 localization and dynamics and provide the necessary groundwork for future studies examining dynamin 2 pathomechanisms and therapy development.
Collapse
Affiliation(s)
- Mo Zhao
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada
| | - Lindsay Smith
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada
| | - Jonathan Volpatti
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada
| | - Lacramioara Fabian
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada
| | - James J Dowling
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada.,Division of Neurology, The Hospital for Sick Children, Toronto, Canada.,Department of Pediatrics, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
| |
Collapse
|
4
|
Saraste J, Prydz K. A New Look at the Functional Organization of the Golgi Ribbon. Front Cell Dev Biol 2019; 7:171. [PMID: 31497600 PMCID: PMC6713163 DOI: 10.3389/fcell.2019.00171] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 08/07/2019] [Indexed: 12/14/2022] Open
Abstract
A characteristic feature of vertebrate cells is a Golgi ribbon consisting of multiple cisternal stacks connected into a single-copy organelle next to the centrosome. Despite numerous studies, the mechanisms that link the stacks together and the functional significance of ribbon formation remain poorly understood. Nevertheless, these questions are of considerable interest, since there is increasing evidence that Golgi fragmentation – the unlinking of the stacks in the ribbon – is intimately connected not only to normal physiological processes, such as cell division and migration, but also to pathological states, including neurodegeneration and cancer. Challenging a commonly held view that ribbon architecture involves the formation of homotypic tubular bridges between the Golgi stacks, we present an alternative model, based on direct interaction between the biosynthetic (pre-Golgi) and endocytic (post-Golgi) membrane networks and their connection with the centrosome. We propose that the central domains of these permanent pre- and post-Golgi networks function together in the biogenesis and maintenance of the more transient Golgi stacks, and thereby establish “linker compartments” that dynamically join the stacks together. This model provides insight into the reversible fragmentation of the Golgi ribbon that takes place in dividing and migrating cells and its regulation along a cell surface – Golgi – centrosome axis. Moreover, it helps to understand transport pathways that either traverse or bypass the Golgi stacks and the positioning of the Golgi apparatus in differentiated neuronal, epithelial, and muscle cells.
Collapse
Affiliation(s)
- Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Kristian Prydz
- Department of Biosciences, University of Oslo, Oslo, Norway
| |
Collapse
|
5
|
Characterisation of L-Type Amino Acid Transporter 1 (LAT1) Expression in Human Skeletal Muscle by Immunofluorescent Microscopy. Nutrients 2017; 10:nu10010023. [PMID: 29278358 PMCID: PMC5793251 DOI: 10.3390/nu10010023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/16/2017] [Accepted: 12/13/2017] [Indexed: 12/21/2022] Open
Abstract
The branch chain amino acid leucine is a potent stimulator of protein synthesis in skeletal muscle. Leucine rapidly enters the cell via the L-Type Amino Acid Transporter 1 (LAT1); however, little is known regarding the localisation and distribution of this transporter in human skeletal muscle. Therefore, we applied immunofluorescence staining approaches to visualise LAT1 in wild type (WT) and LAT1 muscle-specific knockout (mKO) mice, in addition to basal human skeletal muscle samples. LAT1 positive staining was visually greater in WT muscles compared to mKO muscle. In human skeletal muscle, positive LAT1 staining was noted close to the sarcolemmal membrane (dystrophin positive staining), with a greater staining intensity for LAT1 observed in the sarcoplasmic regions of type II fibres (those not stained positively for myosin heavy-chain 1, Type II—25.07 ± 5.93, Type I—13.71 ± 1.98, p < 0.01), suggesting a greater abundance of this protein in these fibres. Finally, we observed association with LAT1 and endothelial nitric oxide synthase (eNOS), suggesting LAT1 association close to the microvasculature. This is the first study to visualise the distribution and localisation of LAT1 in human skeletal muscle. As such, this approach provides a validated experimental platform to study the role and regulation of LAT1 in human skeletal muscle in response to various physiological and pathophysiological models.
Collapse
|
6
|
Long-term regulation of gene expression in muscle cells by systemically delivered siRNA. J Control Release 2017; 256:101-113. [DOI: 10.1016/j.jconrel.2017.04.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 12/20/2022]
|
7
|
Pirkmajer S, Chibalin AV. Na,K-ATPase regulation in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 311:E1-E31. [PMID: 27166285 DOI: 10.1152/ajpendo.00539.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
Collapse
Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
8
|
Vassilopoulos S, Gentil C, Lainé J, Buclez PO, Franck A, Ferry A, Précigout G, Roth R, Heuser JE, Brodsky FM, Garcia L, Bonne G, Voit T, Piétri-Rouxel F, Bitoun M. Actin scaffolding by clathrin heavy chain is required for skeletal muscle sarcomere organization. ACTA ACUST UNITED AC 2014; 205:377-93. [PMID: 24798732 PMCID: PMC4018784 DOI: 10.1083/jcb.201309096] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Clathrin heavy chain contributes to the formation and maintenance of the contractile apparatus in skeletal muscle through interactions with costameric proteins. The ubiquitous clathrin heavy chain (CHC), the main component of clathrin-coated vesicles, is well characterized for its role in intracellular membrane traffic and endocytosis from the plasma membrane (PM). Here, we demonstrate that in skeletal muscle CHC regulates the formation and maintenance of PM–sarcomere attachment sites also known as costameres. We show that clathrin forms large coated lattices associated with actin filaments and the muscle-specific isoform of α-actinin at the PM of differentiated myotubes. Depletion of CHC in myotubes induced a loss of actin and α-actinin sarcomeric organization, whereas CHC depletion in vivo induced a loss of contractile force due to the detachment of sarcomeres from the PM. Our results suggest that CHC contributes to the formation and maintenance of the contractile apparatus through interactions with costameric proteins and highlight an unconventional role for CHC in skeletal muscle that may be relevant to pathophysiology of neuromuscular disorders.
Collapse
Affiliation(s)
- Stéphane Vassilopoulos
- Institut National de la Santé et de la Recherche Médicale (INSERM) U974, 2 Centre National de la Recherche Scientifique (CNRS) UMR 7215, and 3 Université Pierre et Marie Curie-Paris 6, UM 76, Paris F-75013, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Polyxylitol-based gene carrier improves the efficiency of gene transfer through enhanced endosomal osmolysis. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:525-34. [DOI: 10.1016/j.nano.2013.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 08/07/2013] [Accepted: 10/14/2013] [Indexed: 11/17/2022]
|
10
|
Insulin- and contraction-induced glucose transporter 4 traffic in muscle: insights from a novel imaging approach. Exerc Sport Sci Rev 2014; 41:77-86. [PMID: 23072821 DOI: 10.1097/jes.0b013e318275574c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Insulin- and contraction-mediated glucose transporter 4 (GLUT4) trafficking have different kinetics in mature skeletal muscle. Intravital imaging indicates that insulin-stimulated GLUT4 trafficking differs between t-tubules and sarcolemma. In contrast, contraction-induced GLUT4 trafficking does not differ between membrane surfaces. This distinction likely is caused by differences in the underlying signaling pathways regulating GLUT4 vesicle depletion, GLUT4 membrane fusion, and GLUT4 reinternalization.
Collapse
|
11
|
Stanca L, Petrache SN, Radu M, Serban AI, Munteanu MC, Teodorescu D, Staicu AC, Sima C, Costache M, Grigoriu C, Zarnescu O, Dinischiotu A. Impact of silicon-based quantum dots on the antioxidative system in white muscle of Carassius auratus gibelio. FISH PHYSIOLOGY AND BIOCHEMISTRY 2012; 38:963-975. [PMID: 22139144 DOI: 10.1007/s10695-011-9582-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 11/22/2011] [Indexed: 05/31/2023]
Abstract
Silicon-based quantum dots were intraperitoneally injected in individuals of Carassius auratus gibelio. Their effects on white muscle were investigated by following their distribution and impact on the antioxidative system. The GSH level significantly increased after 1 and 3 days of exposure by, respectively, 85.3 and 25.4%. Seven days later, GSH levels were similar to control concentrations. MDA concentration rose after three days by 46.9% and remained at the same level after 7 days. Protein thiol levels significantly decreased by 6.7 and 8.1% after 3 and 7 days, whereas advanced oxidation protein products increased by 12.7, respectively, 28.1% in the same time intervals. The protein reactive carbonyl groups were raised only after the first day of exposure and returned to the control level later on. SOD specific activity increased up to 48% after 7 days, while CAT activity increased by 328, 176, and 26% after 1, 3, and 7 days of treatment. GST specific activity was up-regulated by 87, 18, and 9%, while GR activity increased by 68, 34, and 9%. G6PD activity was up-regulated by 12, 22, and 50%, whereas GPx activity raised by 75 and 109% compared to control after, respectively, 1, 3, and 7 days. Our results suggest that oxidative stress induced by silicon-based quantum dots was not strong enough to cause permanent damage in the white muscle of crucian carp.
Collapse
Affiliation(s)
- Loredana Stanca
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Sorina Nicoleta Petrache
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Mihaela Radu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Andreea Iren Serban
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
- Department of Preclinical Sciences, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine, 105 Splaiul Independetei, 050097, Bucharest, Romania
| | - Maria Cristina Munteanu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Daniela Teodorescu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Andreea Cristina Staicu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Cornelia Sima
- Laser Department, National Institute of Laser, Plasma and Radiation Physics, 409 Atomistilor, 077125, Bucharest-Magurele, Romania
| | - Marieta Costache
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Constantin Grigoriu
- Laser Department, National Institute of Laser, Plasma and Radiation Physics, 409 Atomistilor, 077125, Bucharest-Magurele, Romania
| | - Otilia Zarnescu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania
| | - Anca Dinischiotu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independetei, 050095, Bucharest, Romania.
| |
Collapse
|
12
|
Salova AV, Leontieva EA, Mozhenok TP, Kornilova ES, Krolenko SA, Belyaeva TN. Changes in localization of cellular vesicular apparatus during differentiation of myoblasts into myotubules in cell culture. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s1990519x11030096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
13
|
Phosphoinositide regulation of integrin trafficking required for muscle attachment and maintenance. PLoS Genet 2011; 7:e1001295. [PMID: 21347281 PMCID: PMC3037412 DOI: 10.1371/journal.pgen.1001295] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 01/06/2011] [Indexed: 12/21/2022] Open
Abstract
Muscles must maintain cell compartmentalization when remodeled during development and use. How spatially restricted adhesions are regulated with muscle remodeling is largely unexplored. We show that the myotubularin (mtm) phosphoinositide phosphatase is required for integrin-mediated myofiber attachments in Drosophila melanogaster, and that mtm-depleted myofibers exhibit hallmarks of human XLMTM myopathy. Depletion of mtm leads to increased integrin turnover at the sarcolemma and an accumulation of integrin with PI(3)P on endosomal-related membrane inclusions, indicating a role for Mtm phosphatase activity in endocytic trafficking. The depletion of Class II, but not Class III, PI3-kinase rescued mtm-dependent defects, identifying an important pathway that regulates integrin recycling. Importantly, similar integrin localization defects found in human XLMTM myofibers signify conserved MTM1 function in muscle membrane trafficking. Our results indicate that regulation of distinct phosphoinositide pools plays a central role in maintaining cell compartmentalization and attachments during muscle remodeling, and they suggest involvement of Class II PI3-kinase in MTM-related disease. Muscles require strong extracellular attachments to preserve cellular integrity during force-generating contractions. Integrin transmembrane receptors mediate muscle attachments at highly localized sites, but how this pattern of attachments is continuously maintained with muscle use is not understood. Human X-linked myotubular myopathy (XLMTM), a frequently fatal muscle disease, is associated with mutations in the MTM1 lipid regulator. Myotubularin (MTM) lipid phosphatases are implicated in endocytosis, a process of cellular uptake that can traffic transmembrane receptors for redelivery to the plasma membrane or to protein destruction. Here, we address MTM roles in muscle, using the genetically tractable fruit fly for detailed investigation of muscle cellular organization and functions. We show that fly muscle cells depleted for mtm function exhibit hallmarks of human XLMTM. We found that mtm regulates integrin localization through endocytosis and, in this role, is needed to maintain muscle attachments. Co-depletion of Class II PI3-kinase with mtm restores normal integrin localization at muscle attachment sites and fly survival, identifying a potential therapy target in MTM-related disease. Importantly, we show that integrin localization is also disrupted in human XLMTM. Our work shows conservation of MTM function in integrin trafficking and reveals insights into regulation of muscle cell maintenance and human disease.
Collapse
|
14
|
Nevalainen M, Nissinen M, Kaakinen M, Metsikkö K. Influenza virus infection in multinucleated skeletal myofibers. Exp Cell Res 2010; 316:1784-94. [PMID: 20362571 DOI: 10.1016/j.yexcr.2010.03.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 03/23/2010] [Accepted: 03/26/2010] [Indexed: 11/29/2022]
Abstract
We examined the progression of the WSN influenza virus infection in isolated, multinucleated rat skeletal myofibers. Contrary to mononucleated cells, the adsorbed virions showed markedly delayed entry kinetics. Viral budding occurred on the sarcolemma, but the hemagglutinin envelope glycoprotein matured inefficiently and was poorly cleaved. Compatible with this, plaque assays indicated that infective viral particles were not formed. In situ hybridization studies showed that at low-dose infection, viral RNA production was restricted to one or a few nuclei within a myofiber. Dual in situ hybridization indicated that two different viral RNAs usually co-localized in the same nucleus or nuclei, suggesting that different viral genome segments replicated in the same nucleus. Newly synthesized viral ribonucleoprotein particles (vRNPs) did not re-enter virgin nuclei. Therefore, a single infected nucleus was able to support viral protein production, and notably, these proteins could reach hundreds of micrometers from the nucleus of origin. These results suggest that after viral disassembly in the endosome, the genome segments remained glued together and entered a myonucleus as a package. Spreading of the infection into virgin nuclei either by vRNPs or newly made virions did not occur, and thus the infection was abortive.
Collapse
Affiliation(s)
- Mika Nevalainen
- Institute of Biomedicine, Department of Anatomy and Cell Biology, PO Box 5000, FIN-90014 University of Oulu, Finland
| | | | | | | |
Collapse
|
15
|
Yuan L, Fairchild MJ, Perkins AD, Tanentzapf G. Analysis of integrin turnover in fly myotendinous junctions. J Cell Sci 2010; 123:939-46. [PMID: 20179102 DOI: 10.1242/jcs.063040] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transient (short-term) cell adhesion underlies dynamic processes such as cell migration, whereas stable (long-term) cell adhesion maintains tissue architecture. Ongoing adhesion complex turnover is essential for transient cell adhesion, but it is not known whether turnover is also required for maintenance of long-term adhesion. We used fluorescence recovery after photobleaching to analyze the dynamics of an integrin adhesion complex (IAC) in a model of long-term cell-ECM adhesion, myotendinous junctions (MTJs), in fly embryos and larvae. We found that the IAC undergoes turnover in MTJs and that this process is mediated by clathrin-dependent endocytosis. Moreover, the small GTPase Rab5 can regulate the proportion of IAC components that undergo turnover. Also, altering Rab5 activity weakened MTJs, resulting in muscle defects. In addition, growth of MTJs was concomitant with a decrease in the proportion of IAC components undergoing turnover. We propose that IAC turnover is tightly regulated in long-term cell-ECM adhesions to allow normal tissue growth and maintenance.
Collapse
Affiliation(s)
- Lin Yuan
- Department of Cellular and Physiological Sciences, University of British Columbia, Life Science Institute, 2350 Health Sciences Mall, Vancouver, British Columbia, Canada
| | | | | | | |
Collapse
|
16
|
Piétri-Rouxel F, Gentil C, Vassilopoulos S, Baas D, Mouisel E, Ferry A, Vignaud A, Hourdé C, Marty I, Schaeffer L, Voit T, Garcia L. DHPR alpha1S subunit controls skeletal muscle mass and morphogenesis. EMBO J 2009; 29:643-54. [PMID: 20033060 DOI: 10.1038/emboj.2009.366] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 11/09/2009] [Indexed: 01/03/2023] Open
Abstract
The alpha1S subunit has a dual function in skeletal muscle: it forms the L-type Ca(2+) channel in T-tubules and is the voltage sensor of excitation-contraction coupling at the level of triads. It has been proposed that L-type Ca(2+) channels might also be voltage-gated sensors linked to transcriptional activity controlling differentiation. By using the U7-exon skipping strategy, we have achieved long-lasting downregulation of alpha1S in adult skeletal muscle. Treated muscles underwent massive atrophy while still displaying significant amounts of alpha1S in the tubular system and being not paralysed. This atrophy implicated the autophagy pathway, which was triggered by neuronal nitric oxide synthase redistribution, activation of FoxO3A, upregulation of autophagy-related genes and autophagosome formation. Subcellular investigations showed that this atrophy was correlated with the disappearance of a minor fraction of alpha1S located throughout the sarcolemma. Our results reveal for the first time that this sarcolemmal fraction could have a role in a signalling pathway determining muscle anabolic or catabolic state and might act as a molecular sensor of muscle activity.
Collapse
Affiliation(s)
- France Piétri-Rouxel
- UMR 7215, CNRS, UMR S 974 Inserm, Institut de Myologie, Université Pierre et Marie Curie, Paris, France.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Belyaeva TN, Krolenko SA, Leontieva EA, Mozhenok TP, Salova AV, Faddeeva MD. Acridine orange distribution and fluorescence spectra in myoblasts and single muscle fibers. ACTA ACUST UNITED AC 2009. [DOI: 10.1134/s1990519x09020096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
18
|
Sirsi SR, Schray RC, Guan X, Lykens NM, Williams JH, Erney ML, Lutz GJ. Functionalized PEG-PEI copolymers complexed to exon-skipping oligonucleotides improve dystrophin expression in mdx mice. Hum Gene Ther 2008; 19:795-806. [PMID: 18647087 DOI: 10.1089/hum.2007.129] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Exon-skipping oligonucleotides (ESOs) with 2'-O-methyl modifications are promising compounds for the treatment of Duchenne muscular dystrophy (DMD). However, the usefulness of these compounds is limited by their poor delivery profile to muscle tissue in vivo. We previously established that copolymers made of poly(ethylene imine) (PEI) and poly(ethylene glycol) (PEG) enhanced ESO transfection in skeletal muscle of mdx mice, resulting in widespread distribution of dystrophin-positive fibers, but limited dystrophin expression by Western blot. In an attempt to improve ESO delivery and dystrophin expression, a new formulation of PEG-PEI copolymer was used, along with functionalized derivatives containing either the cell-penetrating peptide TAT (trans-activator of transcription), adsorbed colloidal gold (CG), or both TAT and CG. Tibialis anterior muscles were given three intramuscular injections of various PEG-PEI-ESO polyplexes (3 days apart; 5 microg of ESO per injection) and muscles were harvested 3 weeks after the first injection. Surface modifications of PEG-PEI copolymers with TAT showed the highest level of dystrophin recovery, with a 6-fold increase in dystrophin-positive fibers compared with ESO alone and up to 30% of normal dystrophin expression by Western blot. The adsorption of CG to either PEG-PEI or TAT-PEG-PEI copolymers showed no further improvement in dystrophin expression. Our data indicate that TAT-modified PEG-PEI copolymers are effective carriers for delivery of ESOs to skeletal muscle and are promising compounds for the therapeutic treatment of DMD.
Collapse
Affiliation(s)
- Shashank R Sirsi
- School of Biomedical Engineering, Drexel University, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | |
Collapse
|
19
|
Kaakinen M, Salmela P, Zelenin S, Metsikkö K. Distribution of aquaporin 4 on sarcolemma of fast-twitch skeletal myofibres. Cell Tissue Res 2007; 329:529-39. [PMID: 17593398 DOI: 10.1007/s00441-007-0442-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 05/10/2007] [Indexed: 11/29/2022]
Abstract
The aquaporin 4 (AQP4) water channel is present on the sarcolemma of fast-twitch-type skeletal myofibres. We have examined the distribution of AQP4 in relation to sarcolemmal domain structure and found that AQP4 protein is not evenly distributed on the sarcolemma. Immunofluorescence staining of isolated single myofibres indicated a punctate staining pattern overlapping with the dystrophin glycoprotein complex, but with the transverse tubule openings being left clear. Myotendinous and neuromuscular junctions also lacked AQP4, despite their high content of the dystrophin glycoprotein complex. The destruction of caveoli with methyl-beta-cyclodextrin did not change the distribution of AQP4 at the sarcolemma. Moreover, AQP4 did not float with the caveolar marker caveolin-3 in sucrose gradients after Triton X-100 extraction at 4 degrees C. These data indicated that AQP4 was not associated with caveoli. Surprisingly, m. flexor digitorum brevis fibres, although of the fast-twitch type, often lacked AQP4. Furthermore, those fibres harbouring AQP4 at the sarcolemma showed a regionalized distribution, suggesting that large areas were devoid of the protein. Blockage of the synthesized proteins in the endoplasmic reticulum with brefeldin A showed that, in spite of its regionalized sarcolemmal distribution, AQP4 was synthesized along the entire length of the fibres. These results suggest functional differences in the water permeability of the sarcolemma not only between the fast-twitch muscles, but also within single muscle fibres.
Collapse
Affiliation(s)
- Mika Kaakinen
- Department of Anatomy and Cell Biology, University of Oulu, PO Box 5000, FIN-90014 Oulu, Finland.
| | | | | | | |
Collapse
|
20
|
Fukuda T, Ahearn M, Roberts A, Mattaliano RJ, Zaal K, Ralston E, Plotz PH, Raben N. Autophagy and mistargeting of therapeutic enzyme in skeletal muscle in Pompe disease. Mol Ther 2006; 14:831-9. [PMID: 17008131 PMCID: PMC2693339 DOI: 10.1016/j.ymthe.2006.08.009] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 08/06/2006] [Accepted: 08/17/2006] [Indexed: 11/28/2022] Open
Abstract
Enzyme replacement therapy (ERT) became a reality for patients with Pompe disease, a fatal cardiomyopathy and skeletal muscle myopathy caused by a deficiency of glycogen-degrading lysosomal enzyme acid alpha-glucosidase (GAA). The therapy, which relies on receptor-mediated endocytosis of recombinant human GAA (rhGAA), appears to be effective in cardiac muscle, but less so in skeletal muscle. We have previously shown a profound disturbance of the lysosomal degradative pathway (autophagy) in therapy-resistant muscle of GAA knockout mice (KO). Our findings here demonstrate a progressive age-dependent autophagic buildup in addition to enlargement of glycogen-filled lysosomes in multiple muscle groups in the KO. Trafficking and processing of the therapeutic enzyme along the endocytic pathway appear to be affected by the autophagy. Confocal microscopy of live single muscle fibers exposed to fluorescently labeled rhGAA indicates that a significant portion of the endocytosed enzyme in the KO was trapped as a partially processed form in the autophagic areas instead of reaching its target--the lysosomes. A fluid-phase endocytic marker was similarly mistargeted and accumulated in vesicular structures within the autophagic areas. These findings may explain why ERT often falls short of reversing the disease process and point toward new avenues for the development of pharmacological intervention.
Collapse
Affiliation(s)
- Tokiko Fukuda
- Arthritis and Rheumatism Branch, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | - Meghan Ahearn
- Arthritis and Rheumatism Branch, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | - Ashley Roberts
- Arthritis and Rheumatism Branch, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | | | - Kristien Zaal
- Light Imaging Section, Office of Science and Technology, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | - Evelyn Ralston
- Light Imaging Section, Office of Science and Technology, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | - Paul H. Plotz
- Arthritis and Rheumatism Branch, NIAMS, National Institutes of Health, Bethesda, MD, USA
| | - Nina Raben
- Arthritis and Rheumatism Branch, NIAMS, National Institutes of Health, Bethesda, MD, USA
- Address correspondence to: Nina Raben 9000 Rockville Pike, Clinical Center Bld.10/9N244 NIH, NIAMS, Bethesda, MD 20892-1820 Phone: (301) 496-1474; Fax: (301) 402-0012, E-mail:
| |
Collapse
|
21
|
Nori A, Valle G, Bortoloso E, Turcato F, Volpe P. Calsequestrin targeting to sarcoplasmic reticulum of skeletal muscle fibers. Am J Physiol Cell Physiol 2006; 291:C245-53. [PMID: 16571864 DOI: 10.1152/ajpcell.00370.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calsequestrin (CS) is the low-affinity, high-capacity calcium binding protein segregated to the lumen of terminal cisternae (TC) of the sarcoplasmic reticulum (SR). The physiological role of CS in controlling calcium release from the SR depends on both its intrinsic properties and its localization. The mechanisms of CS targeting were investigated in skeletal muscle fibers and C2C12 myotubes, a model of SR differentiation, with four deletion mutants of epitope (hemagglutinin, HA)-tagged CS: CS-HA24NH2, CS-HA2D, CS-HA3D, and CS-HAHT, a double mutant of the NH2 terminus and domain III. As judged by immunofluorescence of transfected skeletal muscle fibers, only the double CS-HA mutant showed a homogeneous distribution at the sarcomeric I band, i.e., it did not segregate to TC. As shown by subfractionation of microsomes derived from transfected skeletal muscles, CS-HAHT was largely associated to longitudinal SR whereas CS-HA was concentrated in TC. In C2C12 myotubes, as judged by immunofluorescence, not only CS-HAHT but also CS-HA3D and CS-HA2D were not sorted to developing SR. Condensation competence, a property referable to CS oligomerization, was monitored for the several CS-HA mutants in C2C12 myoblasts, and only CS-HA3D was found able to condense. Together, the results indicate that 1) there are at least two targeting sequences at the NH2 terminus and domain III of CS, 2) SR-specific target and structural information is contained in these sequences, 3) heterologous interactions with junctional SR proteins are relevant for segregation, 4) homologous CS-CS interactions are involved in the overall targeting process, and 5) different targeting mechanisms prevail depending on the stage of SR differentiation.
Collapse
Affiliation(s)
- Alessandra Nori
- Dipartimento di Scienze Biomediche Sperimentali, Università degli Studi di Padova, viale G. Colombo 3, 35121 Padua, Italy
| | | | | | | | | |
Collapse
|
22
|
Sirsi SR, Williams JH, Lutz GJ. Poly(ethylene imine)-poly(ethylene glycol) copolymers facilitate efficient delivery of antisense oligonucleotides to nuclei of mature muscle cells of mdx mice. Hum Gene Ther 2006; 16:1307-17. [PMID: 16259564 DOI: 10.1089/hum.2005.16.1307] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Antisense oligonucleotides (AO) can facilitate dystrophin expression via targeted exon skipping in cultured cells of Duchenne muscular dystrophy (DMD) patients and in the mouse model of DMD (mdx mice). However, the lack of effective means to deliver AO to myonuclei remains the foremost limitation to their usefulness in DMD gene therapy. In this study we show that copolymers of cationic poly(ethylene imine) (PEI) and poly(ethylene glycol) (PEG) facilitated efficient cellular uptake and nuclear delivery of AO in mature skeletal muscle fibers isolated from mdx mice. Confocal analysis of dual fluorescently tagged PEG-PEI-AO polyplexes, 24 hr after transfection, showed that the copolymer and AO were colocalized within punctate membrane- associated structures. Importantly, AO was efficiently translocated into myonuclei, whereas the copolymer was mostly excluded. The morphology of all transfected myofibers was perfectly maintained with no indication of damage or cytotoxicity. Quantitative fluorescence analysis showed that transfection with PEG-PEI-AO resulted in a 6-fold higher uptake of AO into myonuclei compared with transfections of AO alone. Interestingly, transfections with rhodamine-labeled PEG-PEI copolymers yielded an approximately 2- fold higher uptake of AO into myonuclei compared with transfections of unlabeled copolymers. Attempts to further increase AO delivery by addition of insulin-transferrin-selenium (ITS) to the medium showed no further improvement in AO delivery. Dose-response analysis indicated saturation of endocytotic uptake of the polyplex. Overall, we conclude that PEG-PEI copolymers represent high-capacity, nontoxic carriers for efficient delivery of AO to nuclei of mature myofibers.
Collapse
Affiliation(s)
- Shashank R Sirsi
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | | | | |
Collapse
|
23
|
Bechet D, Tassa A, Taillandier D, Combaret L, Attaix D. Lysosomal proteolysis in skeletal muscle. Int J Biochem Cell Biol 2005; 37:2098-114. [PMID: 16125113 DOI: 10.1016/j.biocel.2005.02.029] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Revised: 02/09/2005] [Accepted: 02/22/2005] [Indexed: 01/06/2023]
Abstract
Lysosomal proteases are abundantly expressed in fetal muscles, but poorly represented in the adult skeletal muscles. The lysosomal proteolytic system is nonetheless stimulated in adult muscles in a variety of pathological conditions. Furthermore, recent investigations describe autophagosomes in muscle fibers in vitro and in vivo, and report myopathies with excessive autophagy. This review presents our current knowledge about the lysosomal proteolytic system and summarizes the evidences pertaining to the role of lysosomes and autophagosomes in muscle physiology and pathology.
Collapse
Affiliation(s)
- Daniel Bechet
- Human Nutrition Research Center of Clermont-Ferrand, Nutrition and Protein Metabolism Unit, INRA UR551, 63122 Ceyrat, France.
| | | | | | | | | |
Collapse
|
24
|
Kirkham M, Fujita A, Chadda R, Nixon SJ, Kurzchalia TV, Sharma DK, Pagano RE, Hancock JF, Mayor S, Parton RG. Ultrastructural identification of uncoated caveolin-independent early endocytic vehicles. ACTA ACUST UNITED AC 2005; 168:465-76. [PMID: 15668297 PMCID: PMC2171740 DOI: 10.1083/jcb.200407078] [Citation(s) in RCA: 332] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Using quantitative light microscopy and a modified immunoelectron microscopic technique, we have characterized the entry pathway of the cholera toxin binding subunit (CTB) in primary embryonic fibroblasts. CTB trafficking to the Golgi complex was identical in caveolin-1null (Cav1−/−) mouse embryonic fibroblasts (MEFs) and wild-type (WT) MEFs. CTB entry in the Cav1−/− MEFs was predominantly clathrin and dynamin independent but relatively cholesterol dependent. Immunoelectron microscopy was used to quantify budded and surface-connected caveolae and to identify noncaveolar endocytic vehicles. In WT MEFs, a small fraction of the total Cav1-positive structures were shown to bud from the plasma membrane (2% per minute), and budding increased upon okadaic acid or lactosyl ceramide treatment. However, the major carriers involved in initial entry of CTB were identified as uncoated tubular or ring-shaped structures. These carriers contained GPI-anchored proteins and fluid phase markers and represented the major vehicles mediating CTB uptake in both WT and caveolae-null cells.
Collapse
Affiliation(s)
- Matthew Kirkham
- Institute for Molecular Bioscience, University of Queensland, Queensland 4072, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Maurage CA, Bussière T, Sergeant N, Ghesteem A, Figarella-Branger D, Ruchoux MM, Pellissier JF, Delacourte A. Tau aggregates are abnormally phosphorylated in inclusion body myositis and have an immunoelectrophoretic profile distinct from other tauopathies. Neuropathol Appl Neurobiol 2005; 30:624-34. [PMID: 15541003 DOI: 10.1111/j.1365-2990.2004.00577.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sporadic inclusion body myositis (s-IBM) is the most frequent progressive acquired inflammatory myopathy in people older than 50 years. Abnormal aggregates of 'Alzheimer's proteins', including tau proteins, have been previously demonstrated in s-IBM. In the present study, we have investigated by immunohistochemistry and immunoblotting analysis the presence of tau proteins in muscle biopsy samples from patients with s-IBM and other myopathies with rimmed vacuoles, using newly developed antibodies raised against tau protein epitopes found in Alzheimer's disease brain. Tau immunoreactivity was shown in rimmed vacuoles or inclusions, preferentially with antibodies directed against phosphorylated carboxy-terminal epitopes of tau proteins. Cytoplasmic reactivity was also demonstrated in atrophic, nonvacuolated fibres, as well as in non-necrotic fibres invaded by inflammatory cells. Abnormally phosphorylated tau aggregates were also found in other compartments of the muscle fibre in s-IBM and other myopathies. Tau immunoblotting showed an electrophorectic profile of a doublet within the range of 60-62 kDa isovariants, which was different from tauopathies of the central nervous system. Finally, the unique pattern of immunoreactivity of s-IBM samples towards anti-tau antibodies is a new clue to a possible distinct subclass of peripheral tauopathy, different from the tauopathies of the central nervous system.
Collapse
Affiliation(s)
- C-A Maurage
- INSERM U422, Faculté de Médecine, 1 place de Verdun, Lille cedex, France.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Papponen H, Kaisto T, Myllylä VV, Myllylä R, Metsikkö K. Regulated sarcolemmal localization of the muscle-specific ClC-1 chloride channel. Exp Neurol 2005; 191:163-73. [PMID: 15589523 DOI: 10.1016/j.expneurol.2004.07.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 07/08/2004] [Accepted: 07/12/2004] [Indexed: 12/01/2022]
Abstract
The skeletal muscle-specific ClC-1 is a voltage-gated chloride channel protein. Specific antibodies against ClC-1 revealed in muscle sections a sarcolemmal staining that was absent in the myotonic arrested development of righting response (ADR) mouse muscle. The intensity of the sarcolemmal staining varied from one type of muscle to another and in lateral sections showed a typical mosaic pattern that colocalized with beta-dystroglycan and left the transverse tubule openings clear. Surprisingly, in isolated myofibers, the ClC-1 protein was absent from the sarcolemma. Instead, it localized to intracellular I band areas as soon as the myofibers were isolated. When the isolated myofibers were incubated with the kinase inhibitor staurosporine, the ClC-1 protein shifted back to the sarcolemma. Electric stimulation of the cultivated fibers had a similar effect. Also, myofibers infected with a recombinant Semliki Forest virus (SFV) expressing myc-tagged ClC-1 showed intracellular localization of the protein. The virally expressed mycClC-1 reached the Golgi apparatus but sarcolemmal staining remained nondetectable, and addition of staurosporine into the growth medium recruited the mycClC-1 to the sarcolemma. These data indicate that sarcolemmal targeting of the ClC-1 requires specific signals that are provided by the physiological environment.
Collapse
Affiliation(s)
- H Papponen
- Department of Anatomy and Cell Biology, University of Oulu, PO Box 5000, FIN-90014, Finland
| | | | | | | | | |
Collapse
|
27
|
Abstract
Skeletal muscle tissue is made up of highly organized multinuclear cells. The internal organization of the muscle cell is dictated by the necessary regular arrangement of repeated units within the protein myofibrils that mediate muscle contraction. Skeletal muscle cells have the usual membrane traffic pathways for partitioning newly synthesized proteins, internalizing cell surface receptors for hormones and nutrients, and mediating membrane repair. However, in muscle, these pathways must be further specialized to deal with targeting to and organizing muscle-specific membrane structures, satisfying the unique metabolic requirements of muscle and meeting the high demand for membrane repair in a tissue that is constantly under mechanical stress. Specialized membrane traffic pathways in muscle also play a role in the formation of muscle through fusion of myoblast membranes and the development of internal muscle-specific membrane structures during myogenesis and regeneration. It has recently become apparent that muscle-specific isoforms of proteins that are known to mediate ubiquitous membrane traffic pathways, as well as novel muscle-specific proteins, are involved in tissue-specific aspects of muscle membrane traffic. Here we describe the specialized membrane structures of skeletal muscle, how these are developed, maintained and repaired by specialized and generic membrane traffic pathways, and how defects in these pathways result in muscle disease.
Collapse
Affiliation(s)
- Mhairi C Towler
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
| | | | | |
Collapse
|
28
|
Towler MC, Gleeson PA, Hoshino S, Rahkila P, Manalo V, Ohkoshi N, Ordahl C, Parton RG, Brodsky FM. Clathrin isoform CHC22, a component of neuromuscular and myotendinous junctions, binds sorting nexin 5 and has increased expression during myogenesis and muscle regeneration. Mol Biol Cell 2004; 15:3181-95. [PMID: 15133132 PMCID: PMC452575 DOI: 10.1091/mbc.e04-03-0249] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The muscle isoform of clathrin heavy chain, CHC22, has 85% sequence identity to the ubiquitously expressed CHC17, yet its expression pattern and function appear to be distinct from those of well-characterized clathrin-coated vesicles. In mature muscle CHC22 is preferentially concentrated at neuromuscular and myotendinous junctions, suggesting a role at sarcolemmal contacts with extracellular matrix. During myoblast differentiation, CHC22 expression is increased, initially localized with desmin and nestin and then preferentially segregated to the poles of fused myoblasts. CHC22 expression is also increased in regenerating muscle fibers with the same time course as embryonic myosin, indicating a role in muscle repair. CHC22 binds to sorting nexin 5 through a coiled-coil domain present in both partners, which is absent in CHC17 and coincides with the region on CHC17 that binds the regulatory light-chain subunit. These differential binding data suggest a mechanism for the distinct functions of CHC22 relative to CHC17 in membrane traffic during muscle development, repair, and at neuromuscular and myotendinous junctions.
Collapse
Affiliation(s)
- Mhairi C Towler
- The G.W. Hooper Foundation, Department of Microbiology and Immunology and Department of Biopharmaceutical Sciences, University of California, San Francisco, California 94143-0552, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Kuncl RW, Bilak MM, Craig SW, Adams R. Exocytotic "constipation" is a mechanism of tubulin/lysosomal interaction in colchicine myopathy. Exp Cell Res 2003; 285:196-207. [PMID: 12706115 DOI: 10.1016/s0014-4827(03)00034-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Colchicine, a known microtubule disrupting agent, produces a human myopathy, characterized by accumulation of lysosomes. We have created a reliable animal model of colchicine myopathy that replicates the subacute myopathy seen in humans, reproducing the chronic proximal weakness and vacuolar changes in nonnecrotic myofibers. If a microtubule network plays a role in lysosomal function in muscle, disturbance of it could alter degradation of intrinsic membrane receptors, presumably at some intracellular processing site or at exocytosis. Thus, we examined, as a possible cellular pathogenesis of colchicine myopathy, how the muscle cytoskeleton affects the degradation of membrane proteins, which are processed through the endosomal/lysosomal pathway. We used the acetylcholine receptor as a model membrane component in cultured myotubes allowed to preincubate with colchicine. We tested at which step colchicine interferes with receptor trafficking by accounting for internalization, delivery to lysosomes, hydrolysis, or exocytotic release of debris. We report that colchicine significantly decreases the exocytosis of AChRs but does not affect receptor internalization, lysosomal hydrolysis, or the number of surface membrane receptors. Further, our immunofluorescence observations revealed a morphologic tubulin network in rat skeletal muscle that is more densely distributed in white (mitochondria-poor) muscle fibers than in red (mitochondria-rich) fibers but is present in both. Ultrastructurally, immunogold labeling localized tubulin in the intermyofibrillar region in a long and linear fashion, unassociated with myofibers or mitochondria. Taken together, our findings suggest the following: (1) Microtubules likely play a functional role in the pathway of lysosomal degradation in normal adult skeletal muscle; (2) The observed decrease in overall apparent degradation of membrane receptors by colchicine must be due primarily to inhibition of exocytosis. These data indicate that lysosomal "constipation" underlies colchicine myopathy. (3) An animal model faithful to the human disorder will allow further pathogenetic studies.
Collapse
Affiliation(s)
- Ralph W Kuncl
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
| | | | | | | |
Collapse
|
30
|
Soeiro MDNC, Mota RA, Batista DDGJ, Meirelles MDNL. Endocytic pathway in mouse cardiac cells. Cell Struct Funct 2002; 27:469-78. [PMID: 12576639 DOI: 10.1247/csf.27.469] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Primary cultures of heart muscle cells provide powerful tools for cardiac cell biological research that permits both physiological and biochemical approaches. In the present study we analyzed the endocytosis of cardiac cells and presented morphological characterization of the endocytic machinery using markers, which enabled us to follow the fluid-phase, receptor-mediated endocytosis and the internalization of large particles. Our results demonstrated the route of the internalized cargo to early endosomes followed or not by its discharge in the late compartments. We also confirmed the ability of cardiac muscle cells to ingest large particles such as the mannosylated ligand zymosan A, and even internalize whole eukaryotic cells such as the protozoan parasite Trypanosoma cruzi. Since endocytosis is involved in many important cellular functions, the present work contributes to the knowledge of possible additional roles played by cardiac muscle cells besides their well known ability to act as physically energetic cells in the body, constantly contracting without tiring.
Collapse
Affiliation(s)
- Maria de Nazaré Correia Soeiro
- Laboratório de Biologia Celular, Departamento de Ultra-estrutura e Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil 4365, 21045-900 Rio de Janeiro, Brazil.
| | | | | | | |
Collapse
|
31
|
Sweeney ST, Davis GW. Unrestricted synaptic growth in spinster-a late endosomal protein implicated in TGF-beta-mediated synaptic growth regulation. Neuron 2002; 36:403-16. [PMID: 12408844 DOI: 10.1016/s0896-6273(02)01014-0] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In a genetic screen for genes that control synapse development, we have identified spinster (spin), which encodes a multipass transmembrane protein. spin mutant synapses reveal a 200% increase in bouton number and a deficit in presynaptic release. We demonstrate that spin is expressed in both nerve and muscle and is required both pre- and postsynaptically for normal synaptic growth. We have localized Spin to a late endosomal compartment and present evidence for altered endosomal/lysosomal function in spin. We also present evidence that synaptic overgrowth in spin is caused by enhanced/misregulated TGF-beta signaling. TGF-beta receptor mutants show dose-dependent suppression of synaptic overgrowth in spin. Furthermore, mutations in Dad, an inhibitory Smad, cause synapse overgrowth. We present a model for synaptic growth control with implications for the etiology of lysosomal storage and neurodegenerative disease.
Collapse
Affiliation(s)
- Sean T Sweeney
- Department of Biochemistry, 513 Parnassus Avenue, HSE 901, University of California, San Francisco, San Francisco, CA 94143, USA
| | | |
Collapse
|