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Rudolf R. Myosin Va: Capturing cAMP for synaptic plasticity. Front Physiol 2024; 14:1342994. [PMID: 38239886 PMCID: PMC10794446 DOI: 10.3389/fphys.2023.1342994] [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: 11/23/2023] [Accepted: 12/12/2023] [Indexed: 01/22/2024] Open
Abstract
The plus-end directed actin-dependent motor protein, myosin Va, is of particular relevance for outward vesicular protein trafficking and for restraining specific cargo vesicles within the actin cortex. The latter is a preferred site of cAMP production, and the specificity of cAMP signaling is largely mediated through the formation of microdomains that spatially couple localized metabotropic receptor activity and cAMP production to selected effectors and downstream targets. This review summarizes the core literature on the role of myosin Va for the creation of such a cAMP microdomain at the mammalian nerve-muscle synapse that serves the activity-dependent recycling of nicotinic acetylcholine receptors (nAChRs)-a principal ligand-gated ion channel which is imperative for voluntary muscle contraction. It is discussed that i) the nerve-muscle synapse is a site with a unique actin-dependent microstructure, ii) myosin Va and protein kinase A regulatory subunit Iα as well as nAChR and its constitutive binding partner, rapsyn, colocalize in endocytic/recycling vesicles near the postsynaptic membrane, and iii) impairment of myosin Va or displacement of protein kinase A regulatory subunit Iα leads to the loss of nAChR stability. Regulation of this signaling process and underlying basic pieces of machinery were covered in previous articles, to which the present review refers.
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Affiliation(s)
- Rüdiger Rudolf
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
- Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany
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2
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Villarroel-Campos D, Schiavo G, Sleigh JN. Dissection, in vivo imaging and analysis of the mouse epitrochleoanconeus muscle. J Anat 2021; 241:1108-1119. [PMID: 34121181 PMCID: PMC9558155 DOI: 10.1111/joa.13478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022] Open
Abstract
Analysis of rodent muscles affords an opportunity to glean key insights into neuromuscular development and the detrimental impact of disease‐causing genetic mutations. Muscles of the distal leg, for instance the gastrocnemius and tibialis anterior, are commonly used in such studies with mice and rats. However, thin and flat muscles, which can be dissected, processed and imaged without major disruption to muscle fibres and nerve‐muscle contacts, are more suitable for accurate and detailed analyses of the peripheral motor nervous system. One such wholemount muscle is the predominantly fast twitch epitrochleoanconeus (ETA), which is located in the upper forelimb, innervated by the radial nerve, and contains relatively large and uniformly flat neuromuscular junctions (NMJs). To facilitate incorporation of the ETA into the experimental toolkit of the neuromuscular disease field, here, we describe a simple method for its rapid isolation (<5 min), supported by high‐resolution videos and step‐by‐step images. Furthermore, we outline how the ETA can be imaged in live, anaesthetised mice, to enable examination of dynamic cellular processes occurring at the NMJ and within intramuscular axons, including transport of organelles, such as mitochondria and signalling endosomes. Finally, we present reference data on wild‐type ETA fibre‐type composition in young adult, male C57BL6/J mice. Comparative neuroanatomical studies of different muscles in rodent models of disease can generate critical insights into pathogenesis and pathology; dissection of the wholemount ETA provides the possibility to diversify the repertoire of muscles analysed for this endeavour.
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Affiliation(s)
- David Villarroel-Campos
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
| | - James N Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
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Martinez-Pena y Valenzuela I, Akaaboune M. The Metabolic Stability of the Nicotinic Acetylcholine Receptor at the Neuromuscular Junction. Cells 2021; 10:cells10020358. [PMID: 33572348 PMCID: PMC7916148 DOI: 10.3390/cells10020358] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 11/16/2022] Open
Abstract
The clustering and maintenance of nicotinic acetylcholine receptors (AChRs) at high density in the postsynaptic membrane is a hallmark of the mammalian neuromuscular junction (NMJ). The regulation of receptor density/turnover rate at synapses is one of the main thrusts of neurobiology because it plays an important role in synaptic development and synaptic plasticity. The state-of-the-art imaging revealed that AChRs are highly dynamic despite the overall structural stability of the NMJ over the lifetime of the animal. This review highlights the work on the metabolic stability of AChRs at developing and mature NMJs and discusses the role of synaptic activity and the regulatory signaling pathways involved in the dynamics of AChRs.
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Affiliation(s)
| | - Mohammed Akaaboune
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA;
- Program in Neuroscience, University of Michigan, Ann Arbor, MI 48109, USA
- Correspondence: ; Tel.: +1-73-(46)-478512; Fax: +1-73-(46)-470884
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Eiber N, Rehman M, Kravic B, Rudolf R, Sandri M, Hashemolhosseini S. Loss of Protein Kinase Csnk2b/CK2β at Neuromuscular Junctions Affects Morphology and Dynamics of Aggregated Nicotinic Acetylcholine Receptors, Neuromuscular Transmission, and Synaptic Gene Expression. Cells 2019; 8:cells8080940. [PMID: 31434353 PMCID: PMC6721821 DOI: 10.3390/cells8080940] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/21/2019] [Accepted: 08/12/2019] [Indexed: 12/19/2022] Open
Abstract
The protein kinase Csnk2/CK2 is important for cell proliferation, differentiation, and survival. Previously, we showed that CK2 binds distinctive proteins at neuromuscular junctions (NMJs) of mice and phosphorylates some of them. CK2 likely stabilizes clustered nicotinic acetylcholine receptors (AChRs). In the absence of the β-subunit of CK2 in skeletal muscle fibers, mice develop an age-dependent decrease of grip strength accompanied by NMJ fragmentation and impairments of neuromuscular transmission. However, the precise role of CK2β regarding the clustering of AChRs and downstream signaling at NMJs is unknown. Here, we compared conditional CK2β-deficient mice with controls and found in the mutants (1) a lower decrement of endplate potentials after repetitive stimulation and decrements of nerve-evoked compound muscle action potentials decayed more rapidly after synaptic transmission was partially blocked, (2) that their muscle weakness was partially rescued by administration of an acetylcholine esterase inhibitor, (3) fragmented NMJs and impaired AChR clustering was detected in muscles and cultured muscle cells, (4) enlarged myonuclei, (5) impaired synaptic gene expression, and (6) a high turnover rate of their AChR clusters in vivo. Altogether, our data demonstrate a role for CK2 at the NMJ by maintaining a high density of AChRs and ensuring physiological synaptic gene expression.
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Affiliation(s)
- Nane Eiber
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, |91054 Erlangen, Germany
| | - Michael Rehman
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, |91054 Erlangen, Germany
- Weill Cornell Medical College, Department of Medicine, New York, NY 10065, USA
| | - Bojana Kravic
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, |91054 Erlangen, Germany
- Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Rüdiger Rudolf
- Institute of molecular- and cellular biology, University of Applied Sciences Mannheim, |68163 Mannheim, Germany
| | - Marco Sandri
- Department of Biomedical Science, University of Padova, 35122 Padova, Italy
| | - Said Hashemolhosseini
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, |91054 Erlangen, Germany.
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Rudolf R, Straka T. Nicotinic acetylcholine receptor at vertebrate motor endplates: Endocytosis, recycling, and degradation. Neurosci Lett 2019; 711:134434. [PMID: 31421156 DOI: 10.1016/j.neulet.2019.134434] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/08/2019] [Accepted: 08/14/2019] [Indexed: 12/31/2022]
Abstract
At vertebrate motor endplates, the conversion of nerve impulses into muscle contraction is initiated by binding of acetylcholine to its nicotinic receptor (nAChR) at the postsynapse. Efficiency and safety of this process are dependent on proper localization, density, and molecular composition of the receptors. To warrant this, intricate machineries regulating the turnover of nAChR are in place. They control and execute the processes of i) expression, ii) delivery to the postsynaptic membrane, iii) clustering at the plasma membrane, iv) endocytic retrieval, v) activity-dependent recycling, and vi) degradation of nAChR. Concentrating on aspects iv-vi, this review addresses the current status of techniques, concepts, and open questions on endocytosis, recycling, and degradation of nAChR. A picture is emerging, that shows connections between executing machineries and their regulators. The first group includes the actin cytoskeleton, myosin motor proteins, Rab G-proteins, and the autophagic cascade. The second group features protein kinases A and C, Cdk5, and CaMKII as well as other components like the E3-ligase MuRF1 and the membrane shaping regulator, SH3GLB1. Recent studies have started to shed light onto nerve inputs that appear to master the tuning of the postsynaptic protein trafficking apparatus and the expression of critical components for nAChR turnover.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany; Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
| | - Tatjana Straka
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany; Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
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Motor Endplate-Anatomical, Functional, and Molecular Concepts in the Historical Perspective. Cells 2019; 8:cells8050387. [PMID: 31035624 PMCID: PMC6562597 DOI: 10.3390/cells8050387] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 04/20/2019] [Accepted: 04/25/2019] [Indexed: 11/17/2022] Open
Abstract
By mediating voluntary muscle movement, vertebrate neuromuscular junctions (NMJ) play an extraordinarily important role in physiology. While the significance of the nerve-muscle connectivity was already conceived almost 2000 years back, the precise cell and molecular biology of the NMJ have been revealed in a series of fascinating research activities that started around 180 years ago and that continues. In all this time, NMJ research has led to fundamentally new concepts of cell biology, and has triggered groundbreaking advancements in technologies. This review tries to sketch major lines of thought and concepts on NMJ in their historical perspective, in particular with respect to anatomy, function, and molecular components. Furthermore, along these lines, it emphasizes the mutual benefit between science and technology, where one drives the other. Finally, we speculate on potential major future directions for studies on NMJ in these fields.
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Wild F, Khan MM, Rudolf R. Evidence for the subsynaptic zone as a preferential site for CHRN recycling at neuromuscular junctions. Small GTPases 2017; 10:395-402. [PMID: 28489965 DOI: 10.1080/21541248.2017.1324939] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Vertebrate skeletal muscle contraction is mediated by nicotinic acetylcholine receptors (CHRN). Endocytosis and recycling of CHRN regulate their proper abundance at nerve-muscle synapses, i.e. neuromuscular junctions. Recent work showed that RAB5 is essential for CHRN endocytosis. Here, using in vivo-imaging of endocytosed CHRN and RAB-GFP fusion proteins, we deliver evidence for differential effects of RAB5-GFP, RAB4-GFP, and RAB11-GFP on CHRN endocytosis. Furthermore, while newly endocytosed CHRN colocalized with RAB5-GFP over large stretches of muscle fibers, RAB4-GFP and RAB11-GFP colocalized with endocytosed CHRN almost exclusively at neuromuscular junctions. In agreement with previous findings, this data suggests the existence of a specialized subsynaptic zone that is particularly relevant for CHRN recycling.
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Affiliation(s)
- Franziska Wild
- a Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.,b Interdisciplinary Center for Neurosciences, Heidelberg University , Heidelberg , Germany.,c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Muzamil Majid Khan
- a Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.,b Interdisciplinary Center for Neurosciences, Heidelberg University , Heidelberg , Germany.,c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Rüdiger Rudolf
- a Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences , Mannheim , Germany.,b Interdisciplinary Center for Neurosciences, Heidelberg University , Heidelberg , Germany.,c Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
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8
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Tu H, Zhang D, Corrick RM, Muelleman RL, Wadman MC, Li YL. Morphological Regeneration and Functional Recovery of Neuromuscular Junctions after Tourniquet-Induced Injuries in Mouse Hindlimb. Front Physiol 2017; 8:207. [PMID: 28428759 PMCID: PMC5382216 DOI: 10.3389/fphys.2017.00207] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/21/2017] [Indexed: 02/04/2023] Open
Abstract
Tourniquet application and its subsequent release cause serious injuries to the skeletal muscle, nerve, and neuromuscular junction (NMJ) due to mechanical compression and ischemia-reperfusion (IR). Monitoring structural and functional repair of the NMJ, nerve, and skeletal muscle after tourniquet-induced injuries is beneficial in exploring potential cellular and molecular mechanisms responsible for tourniquet-induced injuries, and for establishing effective therapeutic interventions. Here, we observed long-term morphological and functional changes of the NMJ in a murine model of tourniquet-induced hindlimb injuries. Unilateral hindlimbs of C57/BL6 mice were subjected to 3 h of tourniquet by placing an orthodontic rubber band, followed by varied periods of tourniquet release (1 day, 3 days, 1 week, 2 weeks, 4 weeks, and 6 weeks). NMJ morphology in the gastrocnemius muscle was imaged, and the endplate potential (EPP) was recorded to evaluate NMJ function. In NMJs, nicotinic acetylcholine receptor (nAChR) clusters normally displayed an intact, pretzel-like shape, and all nAChR clusters were innervated (100%) by motor nerve terminals. During 3 h of tourniquet application and varied periods of tourniquet release, NMJs in the gastrocnemius muscle were characterized by morphological and functional changes. At 1 day and 3 days of tourniquet release, nAChR clusters retained normal, pretzel-like shapes, whereas motor nerve terminals were completely destroyed and no EPPs recorded. From 1 to 6 weeks of tourniquet release, motor nerve terminals gradually regenerated, even reaching that seen in sham mice, whereas nAChR clusters were gradually fragmented with prolongation of tourniquet release. Additionally, the amplitude of EPPs gradually increased with prolongation of tourniquet release. However, even at 6 weeks after tourniquet release, the amplitude of EPPs did not restore to the level seen in sham mice (13.9 ± 1.1 mV, p < 0.05 vs. sham mice, 29.8 ± 1.0 mV). The data suggest that tourniquet application and subsequent release impair the structure and function of NMJs. Morphological change in motor nerve terminals is faster than in nAChR clusters in NMJs. Slow restoration of fragmented nAChR clusters possibly dampens neuromuscular transmission during the long phase following tourniquet release.
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Affiliation(s)
- Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Ryan M Corrick
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Robert L Muelleman
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Michael C Wadman
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical CenterOmaha, NE, USA.,Department of Cellular and Integrative Physiology, Nebraska Medical CenterOmaha, NE, USA
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9
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Turnover of acetylcholine receptors at the endplate revisited: novel insights into nerve-dependent behavior. J Muscle Res Cell Motil 2015; 36:517-24. [PMID: 26276166 DOI: 10.1007/s10974-015-9418-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
The turnover of nicotinic acetylcholine receptors (AChR) is a critical factor that determines function and safety of neuromuscular transmission at the nerve-muscle synapses, i.e. neuromuscular junctions (NMJs). Previously, three different populations of AChRs exhibiting distinct stereotypic and activity-dependent half-life values were observed in mouse muscles. To address AChR turnover in more detail, we here employed a recently developed longitudinal radioiodine assay that is based on repetitive measurements of radio emission from the same animals over long periods of time in combination with systematic variation of the time elapsed between AChR pulse-labeling and muscle denervation. Modeling of the data revealed profiles of AChR de novo synthesis and receptor incorporation into the postsynaptic membrane. Furthermore, decay of pre-existing AChRs upon denervation showed a peculiar pattern corroborating earlier findings of a two-step stabilization of AChRs.
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Darabid H, Perez-Gonzalez AP, Robitaille R. Neuromuscular synaptogenesis: coordinating partners with multiple functions. Nat Rev Neurosci 2014; 15:630-1. [DOI: 10.1038/nrn3821] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Rudolf R, Khan MM, Labeit S, Deschenes MR. Degeneration of neuromuscular junction in age and dystrophy. Front Aging Neurosci 2014; 6:99. [PMID: 24904412 PMCID: PMC4033055 DOI: 10.3389/fnagi.2014.00099] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/08/2014] [Indexed: 12/27/2022] Open
Abstract
Functional denervation is a hallmark of aging sarcopenia as well as of muscular dystrophy. It is thought to be a major factor reducing skeletal muscle mass, particularly in the case of sarcopenia. Neuromuscular junctions (NMJs) serve as the interface between the nervous and skeletal muscular systems, and thus they may receive pathophysiological input of both pre- and post-synaptic origin. Consequently, NMJs are good indicators of motor health on a systemic level. Indeed, upon sarcopenia and dystrophy, NMJs morphologically deteriorate and exhibit altered characteristics of primary signaling molecules, such as nicotinic acetylcholine receptor and agrin. Since a remarkable reversibility of these changes can be observed by exercise, there is significant interest in understanding the molecular mechanisms underlying synaptic deterioration upon aging and dystrophy and how synapses are reset by the aforementioned treatments. Here, we review the literature that describes the phenomena observed at the NMJ in sarcopenic and dystrophic muscle as well as to how these alterations can be reversed and to what extent. In a second part, the current information about molecular machineries underlying these processes is reported.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Medical Technology, University of Heidelberg and University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Muzamil Majid Khan
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim , Mannheim , Germany ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen , Germany
| | - Siegfried Labeit
- Institute of Integrative Pathophysiology, University Medical Centre Mannheim , Mannheim , Germany
| | - Michael R Deschenes
- Department of Kinesiology and Health Sciences, The College of William and Mary , Williamsburg, VA , USA
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Rudolf R, Bogomolovas J, Strack S, Choi KR, Khan MM, Wagner A, Brohm K, Hanashima A, Gasch A, Labeit D, Labeit S. Regulation of nicotinic acetylcholine receptor turnover by MuRF1 connects muscle activity to endo/lysosomal and atrophy pathways. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1663-1674. [PMID: 22956146 PMCID: PMC3776120 DOI: 10.1007/s11357-012-9468-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 08/20/2012] [Indexed: 06/01/2023]
Abstract
Muscle atrophy is a process of muscle wasting induced under a series of catabolic stress conditions, such as denervation, disuse, cancer cachexia, heart and renal failure, AIDS, and aging. Neuromuscular junctions (NMJs), the synapses between motor neurons and muscle fibers undergo major changes in atrophying muscles, ranging from mild morphological alterations to complete disintegration. In this study, we hypothesized that remodeling of NMJs and muscle atrophy could be linked together. To test this, we examined if a major atrophy-promoting E3 ubiquitin ligase, MuRF1, is involved in the maintenance of NMJs. Immunofluorescence revealed that MuRF1 is highly enriched close to the NMJ. Affinity precipitation and in vivo imaging showed that MuRF1 interacts in endocytic structures with both, acetylcholine receptor, the primary postsynaptic protein of the NMJ, as well as with Bif-1, an autophagy- and endocytosis-regulating factor. In vivo imaging, radio labeling, and weighing approaches demonstrated that metabolic destabilization of acetylcholine receptors and muscle atrophy induced by denervation were significantly rescued in MuRF1-KO animals. Notably, interaction with Bif-1, and the rescue of AChR lifetime and muscle atrophy were specific to MuRF1 but not MuRF2. Our data demonstrate an involvement of MuRF1 in membrane protein-turnover, including the degradation of AChRs at the NMJ under atrophying conditions where MuRF1 also interacts and associates with Bif-1.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim, Windeckstrasse 110, 68163 Mannheim, Germany
- Institute of Medical Technology, University of Heidelberg and University of Applied Sciences Mannheim, Paul-Wittsack-Strasse 10, 68163 Mannheim, Germany
| | - Julius Bogomolovas
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Siegfried Strack
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kyeong-Rok Choi
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Muzamil Majid Khan
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Anika Wagner
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kathrin Brohm
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Akira Hanashima
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Alexander Gasch
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Dittmar Labeit
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Siegfried Labeit
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
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13
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The neuromuscular junction: Selective remodeling of synaptic regulators at the nerve/muscle interface. Mech Dev 2013; 130:402-11. [DOI: 10.1016/j.mod.2012.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 09/18/2012] [Accepted: 09/21/2012] [Indexed: 11/19/2022]
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14
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Röder IV, Strack S, Reischl M, Dahley O, Khan MM, Kassel O, Zaccolo M, Rudolf R. Participation of myosin Va and Pka type I in the regeneration of neuromuscular junctions. PLoS One 2012; 7:e40860. [PMID: 22815846 PMCID: PMC3397957 DOI: 10.1371/journal.pone.0040860] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 06/14/2012] [Indexed: 11/21/2022] Open
Abstract
Background The unconventional motor protein, myosin Va, is crucial for the development of the mouse neuromuscular junction (NMJ) in the early postnatal phase. Furthermore, the cooperative action of protein kinase A (PKA) and myosin Va is essential to maintain the adult NMJ. We here assessed the involvement of myosin Va and PKA in NMJ recovery during muscle regeneration. Methodology/Principal Findings To address a putative role of myosin Va and PKA in the process of muscle regeneration, we used two experimental models the dystrophic mdx mouse and Notexin-induced muscle degeneration/regeneration. We found that in both systems myosin Va and PKA type I accumulate beneath the NMJs in a fiber maturation-dependent manner. Morphologically intact NMJs were found to express stable nicotinic acetylcholine receptors and to accumulate myosin Va and PKA type I in the subsynaptic region. Subsynaptic cAMP signaling was strongly altered in dystrophic muscle, particularly in fibers with severely subverted NMJ morphology. Conclusions/Significance Our data show a correlation between the subsynaptic accumulation of myosin Va and PKA type I on the one hand and NMJ regeneration status and morphology, AChR stability and specificity of subsynaptic cAMP handling on the other hand. This suggests an important role of myosin Va and PKA type I for the maturation of NMJs in regenerating muscle.
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Affiliation(s)
- Ira Verena Röder
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Siegfried Strack
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Markus Reischl
- Institut für Angewandte Informatik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Oliver Dahley
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Muzamil Majid Khan
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Olivier Kassel
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Manuela Zaccolo
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Rüdiger Rudolf
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
- Institut für Medizintechnologie, Universität Heidelberg und Hochschule Mannheim, Mannheim, Germany
- Institut für Molekular- und Zellbiologie, Hochschule Mannheim, Mannheim, Germany
- * E-mail:
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Choi KR, Berrera M, Reischl M, Strack S, Albrizio M, Röder IV, Wagner A, Petersen Y, Hafner M, Zaccolo M, Rudolf R. Rapsyn mediates subsynaptic anchoring of PKA type I and stabilisation of acetylcholine receptor in vivo. J Cell Sci 2012; 125:714-23. [PMID: 22331361 DOI: 10.1242/jcs.092361] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The stabilisation of acetylcholine receptors (AChRs) at the neuromuscular junction depends on muscle activity and the cooperative action of myosin Va and protein kinase A (PKA) type I. To execute its function, PKA has to be present in a subsynaptic microdomain where it is enriched by anchoring proteins. Here, we show that the AChR-associated protein, rapsyn, interacts with PKA type I in C2C12 and T-REx293 cells as well as in live mouse muscle beneath the neuromuscular junction. Molecular modelling, immunoprecipitation and bimolecular fluorescence complementation approaches identify an α-helical stretch of rapsyn to be crucial for binding to the dimerisation and docking domain of PKA type I. When expressed in live mouse muscle, a peptide encompassing the rapsyn α-helical sequence efficiently delocalises PKA type I from the neuromuscular junction. The same peptide, as well as a rapsyn construct lacking the α-helical domain, induces severe alteration of acetylcholine receptor turnover as well as fragmentation of synapses. This shows that rapsyn anchors PKA type I in close proximity to the postsynaptic membrane and suggests that this function is essential for synapse maintenance.
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Affiliation(s)
- Kyeong-Rok Choi
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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16
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Strack S, Petersen Y, Wagner A, Röder IV, Albrizio M, Reischl M, Wacker IU, Wilhelm C, Rudolf R. A novel labeling approach identifies three stability levels of acetylcholine receptors in the mouse neuromuscular junction in vivo. PLoS One 2011; 6:e20524. [PMID: 21655100 PMCID: PMC3107218 DOI: 10.1371/journal.pone.0020524] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/02/2011] [Indexed: 11/23/2022] Open
Abstract
Background The turnover of acetylcholine receptors at the neuromuscular junction is regulated in an activity-dependent manner. Upon denervation and under various other pathological conditions, receptor half-life is decreased. Methodology/Principal Findings We demonstrate a novel approach to follow the kinetics of acetylcholine receptor lifetimes upon pulse labeling of mouse muscles with 125I-α-bungarotoxin in vivo. In contrast to previous assays where residual activity was measured ex vivo, in our setup the same animals are used throughout the whole measurement period, thereby permitting a dramatic reduction of animal numbers at increased data quality. We identified three stability levels of acetylcholine receptors depending on the presence or absence of innervation: one pool of receptors with a long half-life of ∼13 days, a second with an intermediate half-life of ∼8 days, and a third with a short half-life of ∼1 day. Data were highly reproducible from animal to animal and followed simple exponential terms. The principal outcomes of these measurements were reproduced by an optical pulse-labeling assay introduced recently. Conclusions/Significance A novel assay to determine kinetics of acetylcholine receptor turnover with small animal numbers is presented. Our data show that nerve activity acts on muscle acetylcholine receptor stability by at least two different means, one shifting receptor lifetime from short to intermediate and another, which further increases receptor stability to a long lifetime. We hypothesize on possible molecular mechanisms.
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Affiliation(s)
- Siegfried Strack
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Yvonne Petersen
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Anika Wagner
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Ira V. Röder
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marina Albrizio
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Markus Reischl
- Institut für Angewandte Informatik, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Irene U. Wacker
- Institut für Biologische Grenzflächen, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Christoph Wilhelm
- Sicherheitsmanagement Analytische Labore, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Rüdiger Rudolf
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Karlsruhe, Germany
- * E-mail:
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Abstract
In neuroscience, myosin V motor proteins have attracted attention since they are highly expressed in brain, and absence of myosin Va in man leads to a severe neurological disease called Griscelli syndrome. While in some cells myosin V is described to act as a vesicle transport motor, an additional role in exocytosis has emerged recently. In neurons, myosin V has been linked to exocytosis of secretory vesicles and recycling endosomes. Through these functions, it is implied in regulating important brain functions including the release of neuropeptides by exocytosis of large dense-core vesicles and the insertion of neurotransmitter receptors into post-synaptic membranes. This review focuses on the role of myosin V in (i) axonal transport and stimulated exocytosis of large dense-core vesicles to regulate the secretion of neuroactive substances, (ii) tethering of the endoplasmic reticulum at cerebellar synapses to permit long-term depression, (iii) recycling of α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors at hippocampal synapses during long-term potentiation, and (iv) recycling of nicotinic acetylcholine receptors at the neuromuscular junction. Myosin V is thus discussed as an important modulator of synaptic plasticity.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
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