1
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McCarthy CI, Kavalali ET. Nano-organization of synaptic calcium signaling. Biochem Soc Trans 2024; 52:1459-1471. [PMID: 38752834 PMCID: PMC11346461 DOI: 10.1042/bst20231385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/17/2024] [Accepted: 05/03/2024] [Indexed: 06/27/2024]
Abstract
Recent studies suggest an exquisite structural nano-organization within single synapses, where sites of evoked fusion - marked by clustering of synaptic vesicles, active zone proteins and voltage-gated calcium channels - are directly juxtaposed to postsynaptic receptor clusters within nanocolumns. This direct nanometer scale alignment between presynaptic fusion apparatus and postsynaptic receptors is thought to ensure the fidelity of synaptic signaling and possibly allow multiple distinct signals to occur without interference from each other within a single active zone. The functional specificity of this organization is made possible by the inherent nano-organization of calcium signals, where all the different calcium sources such as voltage-gated calcium channels, intracellular stores and store-operated calcium entry have dedicated local targets within their nanodomain to ensure precision of action. Here, we discuss synaptic nano-organization from the perspective of calcium signals, where some of the principal findings from early work in the 1980s continue to inspire current studies that exploit new genetic tools and super-resolution imaging technologies.
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Affiliation(s)
- Clara I. McCarthy
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
| | - Ege T. Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37240-7933, U.S.A
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2
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Sirago G, Pellegrino MA, Bottinelli R, Franchi MV, Narici MV. Loss of neuromuscular junction integrity and muscle atrophy in skeletal muscle disuse. Ageing Res Rev 2023; 83:101810. [PMID: 36471545 DOI: 10.1016/j.arr.2022.101810] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/25/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022]
Abstract
Physical inactivity (PI) is a major risk factor of chronic diseases. A major aspect of PI is loss of muscle mass and strength. The latter phenomenon significantly impacts daily life and represent a major issue for global health. Understandably, skeletal muscle itself has been the major focus of studies aimed at understanding the mechanisms underlying loss of mass and strength. Relatively lesser attention has been given to the contribution of alterations in somatomotor control, despite the fact that these changes can start very early and can occur at multiple levels, from the cortex down to the neuromuscular junction (NMJ). It is well known that exposure to chronic inactivity or immobilization causes a disproportionate loss of force compared to muscle mass, i.e. a loss of specific or intrinsic whole muscle force. The latter phenomenon may be partially explained by the loss of specific force of individual muscle fibres, but several other players are very likely to contribute to such detrimental phenomenon. Irrespective of the length of the disuse period, the loss of force is, in fact, more than two-fold greater than that of muscle size. It is very likely that somatomotor alterations may contribute to this loss in intrinsic muscle force. Here we review evidence that alterations of one component of somatomotor control, namely the neuromuscular junction, occur in disuse. We also discuss some of the novel players in NMJ stability (e.g., homer, bassoon, pannexin) and the importance of new established and emerging molecular markers of neurodegenerative processes in humans such as agrin, neural-cell adhesion molecule and light-chain neurofilaments.
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Affiliation(s)
- Giuseppe Sirago
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy.
| | - Maria A Pellegrino
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Roberto Bottinelli
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy; IRCCS Mondino Foundation, Pavia 27100, Italy
| | - Martino V Franchi
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | - Marco V Narici
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy; CIR-MYO Myology Center, University of Padova, Padova 35131, Italy.
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3
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Verschueren A, Palminha C, Delmont E, Attarian S. Changes in neuromuscular function in elders: Novel techniques for assessment of motor unit loss and motor unit remodeling with aging. Rev Neurol (Paris) 2022; 178:780-787. [PMID: 35863917 DOI: 10.1016/j.neurol.2022.03.019] [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: 01/19/2022] [Revised: 03/08/2022] [Accepted: 03/08/2022] [Indexed: 11/24/2022]
Abstract
Functional muscle fiber denervation is a major contributor to the decline in physical function observed with aging and is now a recognized cause of sarcopenia, a muscle disorder characterized by progressive and generalized degenerative loss of skeletal muscle mass, quality, and strength. There is an interrelationship between muscle strength, motor unit (MU) number, and aging, which suggests that a portion of muscle weakness in seniors may be attributable to the loss of functional MUs. During normal aging, there is a time-related progression of MU loss, an adaptive sprouting followed by a maladaptive sprouting, and continuing recession of terminal Schwann cells leading to a reduced capacity for compensatory reinnervation in elders. In amyotrophic lateral sclerosis, increasing age at onset predicts worse survival ALS and it is possible that age-related depletion of the motor neuron pool may worsen motor neuron disease. MUNE methods are used to estimate the number of functional MU, data from MUNIX arguing for motor neuron loss with aging will be reviewed. Recently, a new MRI technique MU-MRI could be used to assess the MU recruitment or explore the activity of a single MU. This review presents published studies on the changes of neuromuscular function with aging, then focusing on these two novel techniques for assessment of MU loss and MU remodeling.
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Affiliation(s)
- A Verschueren
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France.
| | - C Palminha
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
| | - E Delmont
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
| | - S Attarian
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
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4
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Moreira-Pais A, Ferreira R, Oliveira PA, Duarte JA. A neuromuscular perspective of sarcopenia pathogenesis: deciphering the signaling pathways involved. GeroScience 2022; 44:1199-1213. [PMID: 34981273 DOI: 10.1007/s11357-021-00510-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/26/2021] [Indexed: 12/18/2022] Open
Abstract
The escalation of life expectancy is accompanied by an increase in the prevalence of age-related conditions, such as sarcopenia. Sarcopenia, a muscle condition defined by low muscle strength, muscle quality or quantity, and physical performance, has a high prevalence among the elderly and is associated to increased mortality. The neuromuscular system has been emerging as a key contributor to sarcopenia pathogenesis. Indeed, the age-related degeneration of the neuromuscular junction (NMJ) function and structure may contribute to the loss of muscle strength and ultimately to the loss of muscle mass that characterize sarcopenia. The present mini-review discusses important signaling pathways involved in the function and maintenance of the NMJ, giving emphasis to the ones that might contribute to sarcopenia pathogenesis. Some conceivable biomarkers, such as C-terminal agrin fragment (CAF) and brain-derived neurotrophic factor (BDNF), and therapeutic targets, namely acetylcholine and calcitonin gene-related peptide (CGRP), can be retrieved, making way to future studies to validate their clinical use.
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Affiliation(s)
- Alexandra Moreira-Pais
- CIAFEL, Faculty of Sport, University of Porto, Dr. Plácido da Costa 91, 4200-450, Porto, Portugal. .,LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal. .,Centre for Research and Technology of Agro Environmental and Biological Sciences (CITAB), Inov4Agro, University of Trás-Os-Montes and Alto Douro (UTAD), Quinta de Prados, 5000-801, Vila Real, Portugal.
| | - Rita Ferreira
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Paula A Oliveira
- Centre for Research and Technology of Agro Environmental and Biological Sciences (CITAB), Inov4Agro, University of Trás-Os-Montes and Alto Douro (UTAD), Quinta de Prados, 5000-801, Vila Real, Portugal
| | - José A Duarte
- CIAFEL, Faculty of Sport, University of Porto, Dr. Plácido da Costa 91, 4200-450, Porto, Portugal.,TOXRUN - Toxicology Research Unit, University Institute of Health Sciences, CESPU, CRL, Gandra, Portugal
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5
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Deschenes MR, Trebelhorn AM, High MC, Tufts HL, Oh J. Sensitivity of subcellular components of neuromuscular junctions to decreased neuromuscular activity. Synapse 2021; 75:e22220. [PMID: 34318955 DOI: 10.1002/syn.22220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 12/16/2022]
Abstract
Muscle unloading imparts subtotal disuse on the neuromuscular system resulting in reduced performance capacity. This loss of function, at least in part, can be attributed to disruptions at the neuromuscular junction (NMJ). However, research has failed to document morphological remodeling of the NMJ with short term muscle unloading. Here, rather than quantifying cellular components of the NMJ, we examined subcellular active zone responses to 2 weeks of unloading in male Wistar rats. It was revealed that in the plantaris, but not the soleus muscles, unloading elicited significant (P ≤ 0.05) decrements in active zone staining as measured by Bassoon, and calcium channel expression. It was also discovered that unloading decreased the area of calcium channels staining relative to active zone areas of staining suggesting potential interference in the ability of calcium influx to trigger the release of vesicles docked at the active zone. Post-synaptic adaptations of the motor endplate were not evident. This presynaptic subcellular size reduction was not associated with atrophy of the underlying plantaris muscle fibers, although atrophy of the weight-bearing soleus fibers, where no subcellular remodeling was evident, was noted. These results suggest that the active zone is highly sensitive to alterations in neuromuscular activity, and that morphological adaptation of excitatory and contractile components of the NMJ can occur independently of each other.
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Affiliation(s)
- Michael R Deschenes
- Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, Virginia, USA.,Program in Neuroscience, College of William & Mary, Williamsburg, Virginia, USA
| | - Audrey M Trebelhorn
- Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, Virginia, USA
| | - Madeline C High
- Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, Virginia, USA
| | - Hannah L Tufts
- Program in Neuroscience, College of William & Mary, Williamsburg, Virginia, USA
| | - Jeongeun Oh
- Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, Virginia, USA
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6
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Marcolin G, Franchi MV, Monti E, Pizzichemi M, Sarto F, Sirago G, Paoli A, Maggio M, Zampieri S, Narici M. Active older dancers have lower C-terminal Agrin fragment concentration, better balance and gait performance than sedentary peers. Exp Gerontol 2021; 153:111469. [PMID: 34246731 DOI: 10.1016/j.exger.2021.111469] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 12/12/2022]
Abstract
Motor neuron degeneration, denervation, neuromuscular junction (NMJ) fragmentation and loss of motor units (MUs), play a key-role in the development of sarcopenia. The aim of the present study was to investigate the beneficial effects of regular practice of dancing in physically active elders on concentration of C-terminal Agrin fragment (CAF), a marker of NMJ instability, muscle mass, strength, and physical performance in a group of 16 recreationally active older dancers (AOD; 70.1 ± 3.4 yr) compared to 15 age-matched sedentary peers (OS; 70.9 ± 6.2 yr). Circulating concentration of CAF was measured in serum, while morphology of the vastus lateralis and multifidus muscles was assessed by ultrasound imaging. In addition, the participants underwent two functional performance tests, the Timed Up and Go (TUG) and the 10-meter walk test (10-MWT), a lower and upper limb isometric strength test, a static and a dynamic balance test. Although no statistically significant differences were detected for both muscle morphology and isometric strength, higher CAF concentration (20%, p < 0.01) was found in OS. AOD showed a better performance in TUG (22%, p < 0.001), 10-MWT (17%, p < 0.001) and dynamic balance (25%, p < 0.01) than OS. Notably, CAF concentration correlated with dynamic balance performance (r = 0.3711, p < 0.05). Our results provide evidence that the regular practice of dancing in older age, together with non-structured light aerobic physical activities, is associated to lower CAF concentration and improved walking and balance performance. Our findings also suggest that NMJ instability, as indicated by elevated CAF serum concentration, seems to precede the loss of muscle size and alterations in muscle architecture normally associated with sarcopenia.
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Affiliation(s)
- Giuseppe Marcolin
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Martino V Franchi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Elena Monti
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | - Fabio Sarto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Giuseppe Sirago
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Antonio Paoli
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marcello Maggio
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Sandra Zampieri
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Department of Surgery, Oncology, and Gastroenterology, University of Padova, Padova, Italy
| | - Marco Narici
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Myology Center (CIR-Myo), Department of Biomedical Sciences, University of Padova, Italy.
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7
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Woods BJ, Van Vactor D. miRNA: local guardians of presynaptic function in plasticity and disease. RNA Biol 2021; 18:1014-1024. [PMID: 33586621 PMCID: PMC8216186 DOI: 10.1080/15476286.2020.1871214] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022] Open
Abstract
Environmental fitness is an essential component of animal survival. Fitness is achieved through responsive physiological plasticity of tissues across the entire body, and particularly in the nervous system. At the molecular level, neural plasticity is mediated via gene-environmental interactions whereby developmental cues and experience dependent input adapt neuronal function to ever changing demands. To this end, neuronal gene regulation must be coupled to changes in neural activity. Seminal discoveries of the 20th century demonstrated neural activity modifies gene expression through calcium-dependent gene transcription. Building on this model, recent work over the last two decades shows that mRNA products of transcriptional programming continue to be regulated in the neuron through the activity-dependent post-transcriptional action of microRNAs (miRNAs). miRNAs are special post-transcriptional regulators that can tune gene expression within the spatial and temporal requirements of synaptic compartments. This mode of gene regulation has proven to be essential for synaptic function and plasticity as miRNA loss of function is highly associated with neural disease. In this review we will discuss current perspective on the link between presynaptic plasticity and miRNA biogenesis in the neuron.
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Affiliation(s)
- Brandon J. Woods
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - David Van Vactor
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
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8
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Gandini MA, Zamponi GW. Voltage‐gated calcium channel nanodomains: molecular composition and function. FEBS J 2021; 289:614-633. [DOI: 10.1111/febs.15759] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Maria A. Gandini
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
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9
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Huang L, Zhou H, Chen K, Chen X, Yang G. Learning-Dependent Dendritic Spine Plasticity Is Reduced in the Aged Mouse Cortex. Front Neural Circuits 2020; 14:581435. [PMID: 33324172 PMCID: PMC7726160 DOI: 10.3389/fncir.2020.581435] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/05/2020] [Indexed: 11/13/2022] Open
Abstract
Aging is accompanied by a progressive decrease in learning and memory function. Synaptic loss, one of the hallmarks of normal aging, likely plays an important role in age-related cognitive decline. But little is known about the impact of advanced age on synaptic plasticity and neuronal function in vivo. In this study, we examined the structural dynamics of postsynaptic dendritic spines as well as calcium activity of layer 5 pyramidal neurons in the cerebral cortex of young and old mice. Using transcranial two-photon microscopy, we found that in both sensory and motor cortices, the elimination rates of dendritic spines were comparable between young (3-5 months) and mature adults (8-10 months), but seemed higher in old mice (>20 months), contributing to a reduction of total spine number in the old brain. During the process of motor learning, old mice compared to young mice had fewer new spines formed in the primary motor cortex. Motor training-evoked somatic calcium activity in layer 5 pyramidal neurons of the motor cortex was also lower in old than young mice, which was associated with the decline of motor learning ability during aging. Together, these results demonstrate the effects of aging on learning-dependent synapse remodeling and neuronal activity in the living cortex and suggest that synaptic deficits may contribute to age-related learning impairment.
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Affiliation(s)
- Lianyan Huang
- Department of Anesthesiology, New York University School of Medicine, New York, NY, United States.,Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Hang Zhou
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, United States
| | - Kai Chen
- Department of Anesthesiology, Columbia University Medical Center, New York, NY, United States
| | - Xiao Chen
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Guang Yang
- Department of Anesthesiology, New York University School of Medicine, New York, NY, United States.,Department of Anesthesiology, Columbia University Medical Center, New York, NY, United States
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10
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Badawi Y, Nishimune H. Impairment Mechanisms and Intervention Approaches for Aged Human Neuromuscular Junctions. Front Mol Neurosci 2020; 13:568426. [PMID: 33328881 PMCID: PMC7717980 DOI: 10.3389/fnmol.2020.568426] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/16/2020] [Indexed: 12/19/2022] Open
Abstract
The neuromuscular junction (NMJ) is a chemical synapse formed between a presynaptic motor neuron and a postsynaptic muscle cell. NMJs in most vertebrate species share many essential features; however, some differences distinguish human NMJs from others. This review will describe the pre- and postsynaptic structures of human NMJs and compare them to NMJs of laboratory animals. We will focus on age-dependent declines in function and changes in the structure of human NMJs. Furthermore, we will describe insights into the aging process revealed from mouse models of accelerated aging. In addition, we will compare aging phenotypes to other human pathologies that cause impairments of pre- and postsynaptic structures at NMJs. Finally, we will discuss potential intervention approaches for attenuating age-related NMJ dysfunction and sarcopenia in humans.
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Affiliation(s)
- Yomna Badawi
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, United States
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, United States.,Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, Itabashi, Japan
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11
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Zullo A, Fleckenstein J, Schleip R, Hoppe K, Wearing S, Klingler W. Structural and Functional Changes in the Coupling of Fascial Tissue, Skeletal Muscle, and Nerves During Aging. Front Physiol 2020; 11:592. [PMID: 32670080 PMCID: PMC7327116 DOI: 10.3389/fphys.2020.00592] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/11/2020] [Indexed: 12/18/2022] Open
Abstract
Aging is a one-way process associated with profound structural and functional changes in the organism. Indeed, the neuromuscular system undergoes a wide remodeling, which involves muscles, fascia, and the central and peripheral nervous systems. As a result, intrinsic features of tissues, as well as their functional and structural coupling, are affected and a decline in overall physical performance occurs. Evidence from the scientific literature demonstrates that senescence is associated with increased stiffness and reduced elasticity of fascia, as well as loss of skeletal muscle mass, strength, and regenerative potential. The interaction between muscular and fascial structures is also weakened. As for the nervous system, aging leads to motor cortex atrophy, reduced motor cortical excitability, and plasticity, thus leading to accumulation of denervated muscle fibers. As a result, the magnitude of force generated by the neuromuscular apparatus, its transmission along the myofascial chain, joint mobility, and movement coordination are impaired. In this review, we summarize the evidence about the deleterious effect of aging on skeletal muscle, fascial tissue, and the nervous system. In particular, we address the structural and functional changes occurring within and between these tissues and discuss the effect of inflammation in aging. From the clinical perspective, this article outlines promising approaches for analyzing the composition and the viscoelastic properties of skeletal muscle, such as ultrasonography and elastography, which could be applied for a better understanding of musculoskeletal modifications occurring with aging. Moreover, we describe the use of tissue manipulation techniques, such as massage, traction, mobilization as well as acupuncture, dry needling, and nerve block, to enhance fascial repair.
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Affiliation(s)
- Alberto Zullo
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
- CEINGE Advanced Biotechnologies, Naples, Italy
| | - Johannes Fleckenstein
- Department of Sports Medicine, Institute of Sports Sciences, Goethe-University Frankfurt, Frankfurt, Germany
| | - Robert Schleip
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Department of Sports Medicine and Health Promotion, Friedrich-Schiller University Jena, Jena, Germany
| | - Kerstin Hoppe
- Department of Anaesthesiology, Würzburg University, Würzburg, Germany
| | - Scott Wearing
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Faculty of Health School, Queensland University of Technology, Brisbane, QLD, Australia
| | - Werner Klingler
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Faculty of Health School, Queensland University of Technology, Brisbane, QLD, Australia
- Fascia Research Group, Department of Experimental Anaesthesiology, Ulm University, Ulm, Germany
- Department of Anaesthesiology, SRH Hospital Sigmaringen, Sigmaringen, Germany
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12
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Multiple MuSK signaling pathways and the aging neuromuscular junction. Neurosci Lett 2020; 731:135014. [PMID: 32353380 DOI: 10.1016/j.neulet.2020.135014] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 12/16/2022]
Abstract
The neuromuscular junction (NMJ) is the vehicle for fast, reliable and robust communication between motor neuron and muscle. The unparalleled accessibility of this synapse to morphological, electrophysiological and genetic analysis has yielded an in depth understanding of many molecular components mediating its formation, maturation and stability. However, key questions surrounding the signaling pathways mediating these events and how they play out across the lifetime of the synapse remain unanswered. Such information is critical since the NMJ is necessary for normal movement and is compromised in several settings including myasthenia gravis, amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), muscular dystrophy, sarcopenia and aging. Muscle specific kinase (MuSK) is a central player in most if not all contexts of NMJ formation and stability. However, elucidating the function of this receptor in this range of settings is challenging since MuSK participates in at least three signaling pathways: as a tyrosine kinase-dependent receptor for agrin-LRP4 and Wnts; and, as a kinase-independent BMP co-receptor. Here we focus on NMJ stability during aging and discuss open questions regarding the molecular mechanisms that govern active maintenance of the NMJ, with emphasis on MuSK and the potential role of its multiple signaling contexts.
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13
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14
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Valdez G. Effects of disease-afflicted and aging neurons on the musculoskeletal system. Bone 2019; 122:31-37. [PMID: 30695738 PMCID: PMC6444351 DOI: 10.1016/j.bone.2019.01.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 01/24/2019] [Accepted: 01/25/2019] [Indexed: 01/09/2023]
Abstract
The musculoskeletal system includes skeletal muscles, bones and innervating axons from neurons in the central and peripheral nervous systems. Together, they form the largest structure in the body. They also initiate and coordinate locomotion, provide structural stability, and contribute to metabolism and homeostasis. Because of these functions, much effort has been devoted to ascertaining the impact of acute and chronic stress, such as disease, injury and aging, on the musculoskeletal system. This review will examine the role of the nervous system in the deleterious changes that accrue in skeletal muscles and bones during the progression of neurologic diseases and with advancing age.
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Affiliation(s)
- Gregorio Valdez
- Fralin Biomedical Research Institute, Virginia Tech Carilion, Roanoke, VA, USA; Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA.
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15
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Pyrski M, Tusty M, Eckstein E, Oboti L, Rodriguez-Gil DJ, Greer CA, Zufall F. P/Q Type Calcium Channel Cav2.1 Defines a Unique Subset of Glomeruli in the Mouse Olfactory Bulb. Front Cell Neurosci 2018; 12:295. [PMID: 30233329 PMCID: PMC6131590 DOI: 10.3389/fncel.2018.00295] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/16/2018] [Indexed: 11/24/2022] Open
Abstract
Voltage-gated calcium (Cav) channels are a prerequisite for signal transmission at the first olfactory sensory neuron (OSN) synapse within the glomeruli of the main olfactory bulb (MOB). We showed previously that the N-type Cav channel subunit Cav2.2 is present in the vast majority of glomeruli and plays a central role in presynaptic transmitter release. Here, we identify a distinct subset of glomeruli in the MOB of adult mice that is characterized by expression of the P/Q-type channel subunit Cav2.1. Immunolocalization shows that Cav2.1+ glomeruli reside predominantly in the medial and dorsal MOB, and in the vicinity of the necklace glomerular region close to the accessory olfactory bulb. Few glomeruli are detected on the ventral and lateral MOB. Cav2.1 labeling in glomeruli colocalizes with the presynaptic marker vGlut2 in the axon terminals of OSNs. Electron microscopy shows that Cav2.1+ presynaptic boutons establish characteristic asymmetrical synapses with the dendrites of second-order neurons in the glomerular neuropil. Cav2.1+ glomeruli receive axonal input from OSNs that express molecules of canonical OSNs: olfactory marker protein, the ion channel Cnga2, and the phosphodiesterase Pde4a. In the main olfactory epithelium, Cav2.1 labels a distinct subpopulation of OSNs whose distribution mirrors the topography of the MOB glomeruli, that shows the same molecular signature, and is already present at birth. Together, these experiments identify a unique Cav2.1+ multiglomerular domain in the MOB that may form a previously unrecognized olfactory subsystem distinct from other groups of necklace glomeruli that rely on cGMP signaling mechanisms.
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Affiliation(s)
- Martina Pyrski
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Mahbuba Tusty
- Department of Neuroscience and Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, United States
| | - Eugenia Eckstein
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Livio Oboti
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Diego J. Rodriguez-Gil
- Department of Neuroscience and Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, United States
| | - Charles A. Greer
- Department of Neuroscience and Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, United States
| | - Frank Zufall
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
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16
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Maxwell N, Castro RW, Sutherland NM, Vaughan KL, Szarowicz MD, de Cabo R, Mattison JA, Valdez G. α-Motor neurons are spared from aging while their synaptic inputs degenerate in monkeys and mice. Aging Cell 2018; 17. [PMID: 29397579 PMCID: PMC5847869 DOI: 10.1111/acel.12726] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2017] [Indexed: 12/11/2022] Open
Abstract
Motor function deteriorates with advancing age, increasing the risk of adverse health outcomes. While it is well established that skeletal muscles and neuromuscular junctions (NMJs) degenerate with increasing age, the effect of aging on α‐motor neurons and their innervating synaptic inputs remains largely unknown. In this study, we examined the soma of α‐motor neurons and innervating synaptic inputs in the spinal cord of aged rhesus monkeys and mice, two species with vastly different lifespans. We found that, in both species, α‐motor neurons retain their soma size despite an accumulation of large amounts of cellular waste or lipofuscin. Interestingly, the lipofuscin profile varied considerably, indicating that α‐motor neurons age at different rates. Although the rate of aging varies, α‐motor neurons do not atrophy in old age. In fact, there is no difference in the number of motor axons populating ventral roots in old mice compared to adult mice. Moreover, the transcripts and proteins associated with α‐motor neurons do not decrease in the spinal cord of old mice. However, in aged rhesus monkeys and mice, there were fewer cholinergic and glutamatergic synaptic inputs directly abutting α‐motor neurons, evidence that aging causes α‐motor neurons to shed synaptic inputs. Thus, the loss of synaptic inputs may contribute to age‐related dysfunction of α‐motor neurons. These findings broaden our understanding of the degeneration of the somatic motor system that precipitates motor dysfunction with advancing age.
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Affiliation(s)
- Nicholas Maxwell
- Virginia Tech Carilion Research Institute; Virginia Tech; Roanoke VA USA
| | - Ryan W. Castro
- Virginia Tech Carilion Research Institute; Virginia Tech; Roanoke VA USA
- Graduate Program in Translational Biology, Medicine, and Health; Virginia Tech; Blacksburg VA USA
| | | | - Kelli L. Vaughan
- Translational Gerontology Branch; National Institute on Aging; NIH; Baltimore MD USA
- SoBran, Inc.; Burtonsville MD USA
| | - Mark D. Szarowicz
- Translational Gerontology Branch; National Institute on Aging; NIH; Baltimore MD USA
- SoBran, Inc.; Burtonsville MD USA
| | - Rafael de Cabo
- Translational Gerontology Branch; National Institute on Aging; NIH; Baltimore MD USA
| | - Julie A. Mattison
- Translational Gerontology Branch; National Institute on Aging; NIH; Baltimore MD USA
| | - Gregorio Valdez
- Virginia Tech Carilion Research Institute; Virginia Tech; Roanoke VA USA
- Department of Biological Sciences; Virginia Tech; Blacksburg VA USA
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17
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Dittrich M, Homan AE, Meriney SD. Presynaptic mechanisms controlling calcium-triggered transmitter release at the neuromuscular junction. CURRENT OPINION IN PHYSIOLOGY 2018; 4:15-24. [PMID: 30272045 DOI: 10.1016/j.cophys.2018.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Calcium-triggered neurotransmission underlies most communication in the nervous system. Yet, despite the conserved and essential nature of this process, the molecular underpinnings of calcium-triggered neurotransmission have been difficult to study directly and our understanding to this date remains incomplete. Here we frame more recent efforts to understand this process with a historical perspective of the study of neurotransmitter release at the neuromuscular junction. We focus on the role of calcium channel distribution and organization relative to synaptic vesicles, as well as the nature of the calcium sensors that trigger release. Importantly, we provide a framework for understanding how the function of neurotransmitter release sites, or active zones, contributes to the function of the synapse as a whole.
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Affiliation(s)
| | - Anne E Homan
- Department of Neuroscience, A210 Langley Hall, University of Pittsburgh, Pittsburgh, PA 15260
| | - Stephen D Meriney
- Department of Neuroscience, A210 Langley Hall, University of Pittsburgh, Pittsburgh, PA 15260
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18
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Abstract
Age-dependent declines in muscle function are observed across species. The loss of mobility resulting from the decline in muscle function represents an important health issue and a key determinant of quality of life for the elderly. It is believed that changes in the structure and function of the neuromuscular junction are important contributors to the observed declines in motor function with increased age. Numerous studies indicate that the aging muscle is an important contributor to the deterioration of the neuromuscular junction but the cellular and molecular mechanisms driving the degeneration of the synapse remain incompletely described. Importantly, growing data from both animal models and humans indicate that exercise can rejuvenate the neuromuscular junction and improve motor function. In this review we will focus on the role of muscle-derived neurotrophin signaling in the rejuvenation of the aged neuromuscular junction in response to exercise.
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Affiliation(s)
- Tabita Kreko-Pierce
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, USA.,Barshoph Institute of Longevity and Aging Studies, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, USA
| | - Benjamin A Eaton
- Department of Cellular and Integrative Physiology, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, USA.,Barshoph Institute of Longevity and Aging Studies, University of Texas Health Sciences Center at San Antonio, San Antonio, Texas, USA
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19
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Chand KK, Lee KM, Lee JD, Qiu H, Willis EF, Lavidis NA, Hilliard MA, Noakes PG. Defects in synaptic transmission at the neuromuscular junction precede motor deficits in a TDP‐43
Q331K
transgenic mouse model of amyotrophic lateral sclerosis. FASEB J 2018; 32:2676-2689. [DOI: 10.1096/fj.201700835r] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kirat K. Chand
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Kah Meng Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - John D. Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Hao Qiu
- School of Biomedical Sciences Brisbane Queensland Australia
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20
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Krause Neto W, Silva WDA, Ciena AP, de Souza RR, Anaruma CA, Gama EF. Aging Induces Changes in the Somatic Nerve and Postsynaptic Component without Any Alterations in Skeletal Muscles Morphology and Capacity to Carry Load of Wistar Rats. Front Neurosci 2017; 11:688. [PMID: 29326543 PMCID: PMC5741656 DOI: 10.3389/fnins.2017.00688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 11/22/2017] [Indexed: 01/09/2023] Open
Abstract
The present study aimed to analyze the morphology of the peripheral nerve, postsynaptic compartment, skeletal muscles and weight-bearing capacity of Wistar rats at specific ages. Twenty rats were divided into groups: 10 months-old (ADULT) and 24 months-old (OLD). After euthanasia, we prepared and analyzed the tibial nerve using transmission electron microscopy and the soleus and plantaris muscles for cytofluorescence and histochemistry. For the comparison of the results between groups we used dependent and independent Student's t-test with level of significance set at p ≤ 0.05. For the tibial nerve, the OLD group presented the following alterations compared to the ADULT group: larger area and diameter of both myelinated fibers and axons, smaller area occupied by myelinated and unmyelinated axons, lower numerical density of myelinated fibers, and fewer myelinated fibers with normal morphology. Both aged soleus and plantaris end-plate showed greater total perimeter, stained perimeter, total area and stained area compared to ADULT group (p < 0.05). Yet, aged soleus end-plate presented greater dispersion than ADULT samples (p < 0.05). For the morphology of soleus and plantaris muscles, density of the interstitial volume was greater in the OLD group (p < 0.05). No statistical difference was found between groups in the weight-bearing tests. The results of the present study demonstrated that the aging process induces changes in the peripheral nerve and postsynaptic compartment without any change in skeletal muscles and ability to carry load in Wistar rats.
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Affiliation(s)
- Walter Krause Neto
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Department of Physical Education, São Judas Tadeu University, São Paulo, Brazil
| | - Wellington de Assis Silva
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Department of Physical Education, São Judas Tadeu University, São Paulo, Brazil
| | - Adriano P Ciena
- Laboratory of Morphology and Physical Activity, Department of Physical Education, São Paulo State University, Rio Claro, Brazil
| | - Romeu R de Souza
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Department of Physical Education, São Judas Tadeu University, São Paulo, Brazil
| | - Carlos A Anaruma
- Laboratory of Morphology and Physical Activity, Department of Physical Education, São Paulo State University, Rio Claro, Brazil
| | - Eliane F Gama
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Department of Physical Education, São Judas Tadeu University, São Paulo, Brazil
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21
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Badawi Y, Nishimune H. Presynaptic active zones of mammalian neuromuscular junctions: Nanoarchitecture and selective impairments in aging. Neurosci Res 2017; 127:78-88. [PMID: 29221906 DOI: 10.1016/j.neures.2017.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 11/17/2017] [Accepted: 11/27/2017] [Indexed: 12/16/2022]
Abstract
Neurotransmitter release occurs at active zones, which are specialized regions of the presynaptic membrane. A dense collection of proteins at the active zone provides a platform for molecular interactions that promote recruitment, docking, and priming of synaptic vesicles. At mammalian neuromuscular junctions (NMJs), muscle-derived laminin β2 interacts with presynaptic voltage-gated calcium channels to organize active zones. The molecular architecture of presynaptic active zones has been revealed using super-resolution microscopy techniques that combine nanoscale resolution and multiple molecular identification. Interestingly, the active zones of adult NMJs are not stable structures and thus become impaired during aging due to the selective degeneration of specific active zone proteins. This review will discuss recent progress in the understanding of active zone nanoarchitecture and the mechanisms underlying active zone organization in mammalian NMJs. Furthermore, we will summarize the age-related degeneration of active zones at NMJs, and the role of exercise in maintaining active zones.
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Affiliation(s)
- Yomna Badawi
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA.
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22
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Dependence-induced increase of alcohol self-administration and compulsive drinking mediated by the histone methyltransferase PRDM2. Mol Psychiatry 2017; 22:1746-1758. [PMID: 27573876 PMCID: PMC5677579 DOI: 10.1038/mp.2016.131] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 05/20/2016] [Accepted: 06/01/2016] [Indexed: 12/20/2022]
Abstract
Epigenetic processes have been implicated in the pathophysiology of alcohol dependence, but the specific molecular mechanisms mediating dependence-induced neuroadaptations remain largely unknown. Here, we found that a history of alcohol dependence persistently decreased the expression of Prdm2, a histone methyltransferase that monomethylates histone 3 at the lysine 9 residue (H3K9me1), in the rat dorsomedial prefrontal cortex (dmPFC). Downregulation of Prdm2 was associated with decreased H3K9me1, supporting that changes in Prdm2 mRNA levels affected its activity. Chromatin immunoprecipitation followed by massively parallel DNA sequencing showed that genes involved in synaptic communication are epigenetically regulated by H3K9me1 in dependent rats. In non-dependent rats, viral-vector-mediated knockdown of Prdm2 in the dmPFC resulted in expression changes similar to those observed following a history of alcohol dependence. Prdm2 knockdown resulted in increased alcohol self-administration, increased aversion-resistant alcohol intake and enhanced stress-induced relapse to alcohol seeking, a phenocopy of postdependent rats. Collectively, these results identify a novel epigenetic mechanism that contributes to the development of alcohol-seeking behavior following a history of dependence.
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23
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McLoon LK, Christiansen SP, Ghose GM, Das VE, Mustari MJ. Improvement of Eye Alignment in Adult Strabismic Monkeys by Sustained IGF-1 Treatment. Invest Ophthalmol Vis Sci 2017; 57:6070-6078. [PMID: 27820875 PMCID: PMC5114034 DOI: 10.1167/iovs.16-19739] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The goal of this study was to determine if continuous application of insulin-like growth factor-1 (IGF-1) could improve eye alignment of adult strabismic nonhuman primates and to assess possible mechanisms of effect. Methods A continuous release pellet of IGF-1 was placed on one medial rectus muscle in two adult nonhuman primates (M1, M2) rendered exotropic by the alternating monocular occlusion method during the first months of life. Eye alignment and eye movements were recorded for 3 months, after which M1 was euthanized, and the lateral and medial rectus muscles were removed for morphometric analysis of fiber size, nerve, and neuromuscular density. Results Monkey 1 showed a 40% reduction in strabismus angle, a reduction of exotropia of approximately 11° to 14° after 3 months. Monkey 2 showed a 15% improvement, with a reduction of its exotropia by approximately 3°. The treated medial rectus muscle of M1 showed increased mean myofiber cross-sectional areas. Increases in myofiber size also were seen in the contralateral medial rectus and lateral rectus muscles. Similarly, nerve density increased in the contralateral medial rectus and yoked lateral rectus. Conclusions This study demonstrates that in adult nonhuman primates with a sensory-induced exotropia in infancy, continuous IGF-1 treatment improves eye alignment, resulting in muscle fiber enlargement and altered innervational density that includes the untreated muscles. This supports the view that there is sufficient plasticity in the adult ocular motor system to allow continuous IGF-1 treatment over months to produce improvement in eye alignment in early-onset strabismus.
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Affiliation(s)
- Linda K McLoon
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States 2Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States
| | - Stephen P Christiansen
- Departments of Ophthalmology and Pediatrics, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Geoffrey M Ghose
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States
| | - Vallabh E Das
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Michael J Mustari
- Washington National Primate Center and Department of Ophthalmology, University of Washington, Seattle, Washington, United States
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24
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Ross JA, Webster RG, Lechertier T, Reynolds LE, Turmaine M, Bencze M, Jamshidi Y, Cetin H, Muntoni F, Beeson D, Hodilvala-Dilke K, Conti FJ. Multiple roles of integrin-α3 at the neuromuscular junction. J Cell Sci 2017; 130:1772-1784. [PMID: 28386022 PMCID: PMC5450193 DOI: 10.1242/jcs.201103] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 03/31/2017] [Indexed: 12/22/2022] Open
Abstract
The neuromuscular junction (NMJ) is the synapse between motoneurons and skeletal muscle, and is responsible for eliciting muscle contraction. Neurotransmission at synapses depends on the release of synaptic vesicles at sites called active zones (AZs). Various proteins of the extracellular matrix are crucial for NMJ development; however, little is known about the identity and functions of the receptors that mediate their effects. Using genetically modified mice, we find that integrin-α3 (encoded by Itga3), an adhesion receptor at the presynaptic membrane, is involved in the localisation of AZ components and efficient synaptic vesicle release. Integrin-α3 also regulates integrity of the synapse - mutant NMJs present with progressive structural changes and upregulated autophagy, features commonly observed during ageing and in models of neurodegeneration. Unexpectedly, we find instances of nerve terminal detachment from the muscle fibre; to our knowledge, this is the first report of a receptor that is required for the physical anchorage of pre- and postsynaptic elements at the NMJ. These results demonstrate multiple roles of integrin-α3 at the NMJ, and suggest that alterations in its function could underlie defects that occur in neurodegeneration or ageing.
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Affiliation(s)
- Jacob A Ross
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Richard G Webster
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Tanguy Lechertier
- Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Louise E Reynolds
- Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Mark Turmaine
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Maximilien Bencze
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Yalda Jamshidi
- Department of Genetics, Institute of Molecular and Clinical Sciences, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Hakan Cetin
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Kairbaan Hodilvala-Dilke
- Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Francesco J Conti
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
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25
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Hirano M, Takada Y, Wong CF, Yamaguchi K, Kotani H, Kurokawa T, Mori MX, Snutch TP, Ronjat M, De Waard M, Mori Y. C-terminal splice variants of P/Q-type Ca 2+ channel Ca V2.1 α 1 subunits are differentially regulated by Rab3-interacting molecule proteins. J Biol Chem 2017; 292:9365-9381. [PMID: 28377503 DOI: 10.1074/jbc.m117.778829] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/26/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-dependent Ca2+ channels (VDCCs) mediate neurotransmitter release controlled by presynaptic proteins such as the scaffolding proteins Rab3-interacting molecules (RIMs). RIMs confer sustained activity and anchoring of synaptic vesicles to the VDCCs. Multiple sites on the VDCC α1 and β subunits have been reported to mediate the RIMs-VDCC interaction, but their significance is unclear. Because alternative splicing of exons 44 and 47 in the P/Q-type VDCC α1 subunit CaV2.1 gene generates major variants of the CaV2.1 C-terminal region, known for associating with presynaptic proteins, we focused here on the protein regions encoded by these two exons. Co-immunoprecipitation experiments indicated that the C-terminal domain (CTD) encoded by CaV2.1 exons 40-47 interacts with the α-RIMs, RIM1α and RIM2α, and this interaction was abolished by alternative splicing that deletes the protein regions encoded by exons 44 and 47. Electrophysiological characterization of VDCC currents revealed that the suppressive effect of RIM2α on voltage-dependent inactivation (VDI) was stronger than that of RIM1α for the CaV2.1 variant containing the region encoded by exons 44 and 47. Importantly, in the CaV2.1 variant in which exons 44 and 47 were deleted, strong RIM2α-mediated VDI suppression was attenuated to a level comparable with that of RIM1α-mediated VDI suppression, which was unaffected by the exclusion of exons 44 and 47. Studies of deletion mutants of the exon 47 region identified 17 amino acid residues on the C-terminal side of a polyglutamine stretch as being essential for the potentiated VDI suppression characteristic of RIM2α. These results suggest that the interactions of the CaV2.1 CTD with RIMs enable CaV2.1 proteins to distinguish α-RIM isoforms in VDI suppression of P/Q-type VDCC currents.
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Affiliation(s)
- Mitsuru Hirano
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Yoshinori Takada
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Chee Fah Wong
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and.,the Department of Biology, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak, Malaysia
| | - Kazuma Yamaguchi
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Hiroshi Kotani
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Tatsuki Kurokawa
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Masayuki X Mori
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and
| | - Terrance P Snutch
- the Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada, and
| | - Michel Ronjat
- the LabEx Ion Channels, Science and Therapeutics, INSERM UMR1087/CNRS UMR6291, Institut du Thorax, Université de Nantes, Nantes F-44000, France
| | - Michel De Waard
- the LabEx Ion Channels, Science and Therapeutics, INSERM UMR1087/CNRS UMR6291, Institut du Thorax, Université de Nantes, Nantes F-44000, France
| | - Yasuo Mori
- From the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, and .,the Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto 615-8510, Japan
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26
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Chung T, Park JS, Kim S, Montes N, Walston J, Höke A. Evidence for dying-back axonal degeneration in age-associated skeletal muscle decline. Muscle Nerve 2017; 55:894-901. [PMID: 27464347 DOI: 10.1002/mus.25267] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 07/21/2016] [Accepted: 07/26/2016] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Age-associated muscle strength decline is a major contributing factor to increased late-life functional decline and comorbidity, and is strongly associated with early mortality. Although all parts of the neuromuscular system seem to be affected by aging, dying-back of motor axons likely plays a major role. METHODS We compared the degeneration in ventral roots and neuromuscular junction denervation in young and aged mice and correlated the findings with strength and electrophysiological measures. RESULTS With normal aging, there is little decline in motor axon numbers in the ventral roots, but the neuromuscular junctions show marked partial denervation that is associated with increased jitter on stimulated single fiber electromyography and a decrease in muscle strength. CONCLUSIONS These findings suggest that dying-back axonal degeneration may be partially responsible for the electrophysiological and strength changes observed with aging. Muscle Nerve 55: 894-901, 2017.
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Affiliation(s)
- Tae Chung
- Department of Physical Medicine and Rehabilitation, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Jae Sung Park
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA.,Department of Physical Education, Kongju National University, Gongju, Republic of Korea
| | - Sangri Kim
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA
| | - Nataly Montes
- Department of Physical Medicine and Rehabilitation, VA Caribbean Healthcare System, San Juan, Puerto Rico
| | - Jeremy Walston
- Department of Medicine, Johns Hopkins, Baltimore, Maryland, USA
| | - Ahmet Höke
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA
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27
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Liu ZH, Yip PK, Priestley JV, Michael-Titus AT. A Single Dose of Docosahexaenoic Acid Increases the Functional Recovery Promoted by Rehabilitation after Cervical Spinal Cord Injury in the Rat. J Neurotrauma 2017; 34:1766-1777. [PMID: 27881040 DOI: 10.1089/neu.2016.4556] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Task-specific rehabilitation has been shown to promote functional recovery after acute spinal cord injury (SCI). Recently, the omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA), has been shown to promote neuroplasticity after SCI. Here, we investigated whether the combination of a single bolus of DHA with rehabilitation can enhance the effect of DHA or rehabilitation therapy in adult injured spinal cord. We found enhanced functional improvement with DHA in combination with rehabilitation compared with either treatment alone in a rat cervical lateral hemisection SCI model. This behavioral improvement correlated with a significant sprouting of uninjured corticospinal and serotonergic fibers. We also observed that the greatest increase in the synaptic vesicle protein, synaptophysin, and the synaptic active zone protein, Bassoon, occurred in animals that received both DHA and rehabilitation. In summary, the functional, anatomical, and synaptic plasticity induced by task-specific rehabilitation can be further enhanced by DHA treatment. This study shows the potential beneficial effects of DHA combined with rehabilitation for the treatment of patients with SCI.
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Affiliation(s)
- Zhou-Hao Liu
- 1 Queen Mary University of London , Barts and The London School of Medicine and Dentistry, Blizard Institute, London, United Kingdom .,2 Chang Gung Medical College and University , Chang Gung Memorial Hospital, Department of Neurosurgery, Linkou, Taiwan
| | - Ping K Yip
- 1 Queen Mary University of London , Barts and The London School of Medicine and Dentistry, Blizard Institute, London, United Kingdom
| | - John V Priestley
- 1 Queen Mary University of London , Barts and The London School of Medicine and Dentistry, Blizard Institute, London, United Kingdom
| | - Adina T Michael-Titus
- 1 Queen Mary University of London , Barts and The London School of Medicine and Dentistry, Blizard Institute, London, United Kingdom
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Ma D, Shuler JM, Kumar A, Stanford QR, Tungtur S, Nishimune H, Stanford JA. Effects of Tongue Force Training on Bulbar Motor Function in the Female SOD1-G93A Rat Model of Amyotrophic Lateral Sclerosis. Neurorehabil Neural Repair 2016; 31:147-156. [PMID: 27573800 DOI: 10.1177/1545968316666956] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND The use of exercise in amyotrophic lateral sclerosis (ALS) is controversial. Although moderate exercise appears to be beneficial for limb muscles in ALS, the effects of exercise on bulbar muscles such as the tongue have not been studied. OBJECTIVE To determine the effects of tongue force training on bulbar motor function in the SOD1-G93A rat model of ALS. METHODS We compared the effects of tongue force training on bulbar motor function and neuromuscular junction innervation in female SOD1-G93A rats and age-matched female wild-type controls. Half of each group underwent afternoon tongue force training sessions, and all rats were tested under minimal force conditions in the mornings. RESULTS Tongue force did not differ between the SOD1-G93A rats and healthy controls during the morning testing sessions, nor was it affected by training. Surprisingly, decreases in tongue motility, the number of licks per session, and body weight were greater in the tongue force-trained SOD1-G93A rats. Forelimb grip force, survival, and denervation of the genioglossus (GG) muscle did not differ between the trained and untrained SOD1-G93A rats. GG innervation was correlated with changes in tongue force but not tongue motility in SOD1-G93A rats at end stage. CONCLUSIONS The results indicate a potential deleterious effect of tongue force training on tongue motility in female SOD1-G93A rats. The lack of a relationship between GG innervation and tongue motility suggests that factors other than lower-motor neuron integrity likely accounted for this effect.
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Affiliation(s)
- Delin Ma
- 1 Huazhong University of Science and Technology, Wuhan, Hubei Province, China
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Rogers RS, Nishimune H. The role of laminins in the organization and function of neuromuscular junctions. Matrix Biol 2016; 57-58:86-105. [PMID: 27614294 DOI: 10.1016/j.matbio.2016.08.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/10/2016] [Accepted: 08/17/2016] [Indexed: 01/11/2023]
Abstract
The synapse between motor neurons and skeletal muscle is known as the neuromuscular junction (NMJ). Proper alignment of presynaptic and post-synaptic structures of motor neurons and muscle fibers, respectively, is essential for efficient motor control of skeletal muscles. The synaptic cleft between these two cells is filled with basal lamina. Laminins are heterotrimer extracellular matrix molecules that are key members of the basal lamina. Laminin α4, α5, and β2 chains specifically localize to NMJs, and these laminin isoforms play a critical role in maintenance of NMJs and organization of synaptic vesicle release sites known as active zones. These individual laminin chains exert their role in organizing NMJs by binding to their receptors including integrins, dystroglycan, and voltage-gated calcium channels (VGCCs). Disruption of these laminins or the laminin-receptor interaction occurs in neuromuscular diseases including Pierson syndrome and Lambert-Eaton myasthenic syndrome (LEMS). Interventions to maintain proper level of laminins and their receptor interactions may be insightful in treating neuromuscular diseases and aging related degeneration of NMJs.
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Affiliation(s)
- Robert S Rogers
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, USA.
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, USA.
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Dual-color STED microscopy reveals a sandwich structure of Bassoon and Piccolo in active zones of adult and aged mice. Sci Rep 2016; 6:27935. [PMID: 27321892 PMCID: PMC4913281 DOI: 10.1038/srep27935] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/16/2016] [Indexed: 11/08/2022] Open
Abstract
Presynaptic active zones play a pivotal role as synaptic vesicle release sites for synaptic transmission, but the molecular architecture of active zones in mammalian neuromuscular junctions (NMJs) at sub-diffraction limited resolution remains unknown. Bassoon and Piccolo are active zone specific cytosolic proteins essential for active zone assembly in NMJs, ribbon synapses, and brain synapses. These proteins are thought to colocalize and share some functions at active zones. Here, we report an unexpected finding of non-overlapping localization of these two proteins in mouse NMJs revealed using dual-color stimulated emission depletion (STED) super resolution microscopy. Piccolo puncta sandwiched Bassoon puncta and aligned in a Piccolo-Bassoon-Piccolo structure in adult NMJs. P/Q-type voltage-gated calcium channel (VGCC) puncta colocalized with Bassoon puncta. The P/Q-type VGCC and Bassoon protein levels decreased significantly in NMJs from aged mouse. In contrast, the Piccolo levels in NMJs from aged mice were comparable to levels in adult mice. This study revealed the molecular architecture of active zones in mouse NMJs at sub-diffraction limited resolution, and described the selective degeneration mechanism of active zone proteins in NMJs from aged mice. Interestingly, the localization pattern of active zone proteins described herein is similar to active zone structures described using electron microscope tomography.
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Gundelfinger ED, Reissner C, Garner CC. Role of Bassoon and Piccolo in Assembly and Molecular Organization of the Active Zone. Front Synaptic Neurosci 2016; 7:19. [PMID: 26793095 PMCID: PMC4709825 DOI: 10.3389/fnsyn.2015.00019] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/14/2015] [Indexed: 01/05/2023] Open
Abstract
Bassoon and Piccolo are two very large scaffolding proteins of the cytomatrix assembled at the active zone (CAZ) where neurotransmitter is released. They share regions of high sequence similarity distributed along their entire length and seem to share both overlapping and distinct functions in organizing the CAZ. Here, we survey our present knowledge on protein-protein interactions and recent progress in understanding of molecular functions of these two giant proteins. These include roles in the assembly of active zones (AZ), the localization of voltage-gated Ca2+ channels (VGCCs) in the vicinity of release sites, synaptic vesicle (SV) priming and in the case of Piccolo, a role in the dynamic assembly of the actin cytoskeleton. Piccolo and Bassoon are also important for the maintenance of presynaptic structure and function, as well as for the assembly of CAZ specializations such as synaptic ribbons. Recent findings suggest that they are also involved in the regulation activity-dependent communication between presynaptic boutons and the neuronal nucleus. Together these observations suggest that Bassoon and Piccolo use their modular structure to organize super-molecular complexes essential for various aspects of presynaptic function.
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Affiliation(s)
- Eckart D Gundelfinger
- Department Neurochemistry and Molecular Biology, Leibniz Institute for NeurobiologyMagdeburg, Germany; Center for Behavioral Brain SciencesMagdeburg, Germany; Medical Faculty, Otto von Guericke UniversityMagdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Site MagdeburgMagdeburg, Germany
| | - Carsten Reissner
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University Münster, Germany
| | - Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE) Site BerlinBerlin, Germany; Charité Medical UniversityBerlin, Germany
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Krause Neto W, Ciena AP, Anaruma CA, de Souza RR, Gama EF. Effects of exercise on neuromuscular junction components across age: systematic review of animal experimental studies. BMC Res Notes 2015; 8:713. [PMID: 26601719 PMCID: PMC4658757 DOI: 10.1186/s13104-015-1644-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/28/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND During almost one-third of our life, maturation of the nervous system promotes strength and muscle mass increase. However, as age advances, the nervous system begins to suffer a slow and continue reduction of its functions. Neuromuscular junction (NMJ) is one of the structures of which change due to aging process. Physical training leads to significant adjustments in NMJs of young and aged animals. Nevertheless, studies that aimed to investigate this effect have, in many cases, methodological variables that may have some influence on the result. Thus, this study aimed to carry out a systematic review about the effects of exercise training on the NMJ compartments of young, adult and aged animals. RESULTS We searched PubMed, Google Scholar, Science Direct, Scielo and Lilacs databases for animal experimental studies that studied exercise effects on the NMJs components across age. After inclusion and exclusion criteria, we included nine articles in systematic review and two for meta-analysis (young/adult NMJ). CONCLUSIONS We identified that exercise training cause NMJ hypertrophy on young animals and NMJ compression on aged ones. However, many methodological issues such as age, skeletal muscle and fibers type, and type of exercise and training protocol might influence the results. Graphical abstract: Flow gram is actually to be show at results section as Fig 1.
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Affiliation(s)
- Walter Krause Neto
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Physical Education Department, São Judas Tadeu University, Unidade Mooca, Rua Taquari, 546, Mooca, P.O Box: 03166-000, São Paulo, SP, Brazil.
| | - Adriano Polican Ciena
- Laboratory of Histology and Electron Microscopy, Physical Education Department, "Julio de Mesquita Filho" São Paulo State University, Rio Claro, SP, Brazil.
| | - Carlos Alberto Anaruma
- Laboratory of Histology and Electron Microscopy, Physical Education Department, "Julio de Mesquita Filho" São Paulo State University, Rio Claro, SP, Brazil.
| | - Romeu Rodrigues de Souza
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Physical Education Department, São Judas Tadeu University, Unidade Mooca, Rua Taquari, 546, Mooca, P.O Box: 03166-000, São Paulo, SP, Brazil.
| | - Eliane Florencio Gama
- Laboratory of Morphoquantitative Studies and Immunohistochemistry, Physical Education Department, São Judas Tadeu University, Unidade Mooca, Rua Taquari, 546, Mooca, P.O Box: 03166-000, São Paulo, SP, Brazil.
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Theme 14 Therapeutic Strategies. Amyotroph Lateral Scler Frontotemporal Degener 2015; 16 Suppl 1:227-49. [DOI: 10.3109/21678421.2015.1098819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Plomp JJ, Morsch M, Phillips WD, Verschuuren JJGM. Electrophysiological analysis of neuromuscular synaptic function in myasthenia gravis patients and animal models. Exp Neurol 2015; 270:41-54. [PMID: 25620417 DOI: 10.1016/j.expneurol.2015.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/07/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Study of the electrophysiological function of the neuromuscular junction (NMJ) is instrumental in the understanding of the symptoms and pathophysiology of myasthenia gravis (MG), an autoimmune disorder characterized by fluctuating and fatigable muscle weakness. Most patients have autoantibodies to the acetylcholine receptor at the NMJ. However, in recent years autoantibodies to other crucial postsynaptic membrane proteins have been found in previously 'seronegative' MG patients. Electromyographical recording of compound and single-fibre muscle action potentials provides a crucial in vivo method to determine neuromuscular transmission failure while ex vivo (miniature) endplate potential recordings can reveal the precise synaptic impairment. Here we will review these electrophysiological methods used to assess NMJ function and discuss their application and typical results found in the diagnostic and experimental study of patients and animal models of the several forms of MG.
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Affiliation(s)
- Jaap J Plomp
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
| | - Marco Morsch
- Motor Neuron Disease Research Group, Macquarie University, Sydney, Australia
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The active zone protein family ELKS supports Ca2+ influx at nerve terminals of inhibitory hippocampal neurons. J Neurosci 2015; 34:12289-303. [PMID: 25209271 DOI: 10.1523/jneurosci.0999-14.2014] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In a presynaptic nerve terminal, synaptic vesicle exocytosis is restricted to specialized sites called active zones. At these sites, neurotransmitter release is determined by the number of releasable vesicles and their probability of release. Proteins at the active zone set these parameters by controlling the presynaptic Ca(2+) signal, and through docking and priming of synaptic vesicles. Vertebrate ELKS proteins are enriched at presynaptic active zones, but their functions are not well understood. ELKS proteins are produced by two genes in vertebrates, and each gene contributes ∼50% to total brain ELKS. We generated knock-out mice for ELKS1 and found that its constitutive removal causes lethality. To bypass lethality, and to circumvent redundancy between ELKS1 and ELKS2 in synaptic transmission, we used a conditional genetic approach to remove both genes in cultured hippocampal neurons after synapses are established. Simultaneous removal of ELKS1 and ELKS2 resulted in a 50% decrease of neurotransmitter release at inhibitory synapses, paralleled by a reduction in release probability. Removal of ELKS did not affect synapse numbers or their electron microscopic appearance. Using Ca(2+) imaging, we found that loss of ELKS caused a 30% reduction in single action potential-triggered Ca(2+) influx in inhibitory nerve terminals, consistent with the deficits in synaptic transmission and release probability. Unlike deletion of the active zone proteins RIM, RIM-BP, or bruchpilot, ELKS removal did not lead to a measurable reduction in presynaptic Ca(2+) channel levels. Our results reveal that ELKS is required for normal Ca(2+) influx at nerve terminals of inhibitory hippocampal neurons.
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Chand KK, Lee KM, Schenning MP, Lavidis NA, Noakes PG. Loss of β2-laminin alters calcium sensitivity and voltage-gated calcium channel maturation of neurotransmission at the neuromuscular junction. J Physiol 2014; 593:245-65. [PMID: 25556799 DOI: 10.1113/jphysiol.2014.284133] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/23/2014] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Neuromuscular junctions from β2-laminin-deficient mice exhibit lower levels of calcium sensitivity. Loss of β2-laminin leads to a failure in switching from N- to P/Q-type voltage-gated calcium channel (VGCC)-mediated transmitter release that normally occurs with neuromuscular junction maturation. The motor nerve terminals from β2-laminin-deficient mice fail to up-regulate the expression of P/Q-type VGCCs clusters and down-regulate N-type VGCCs clusters, as they mature. There is decreased co-localisation of presynaptic specialisations in β2-laminin-deficient neuromuscular junctions as a consequence of lesser P/Q-type VGCC expression. These findings support the idea that β2-laminin is critical in the organisation and maintenance of active zones at the neuromuscular junction via its interaction with P/Q-type VGCCs, which aid in stabilisation of the synapse. β2-laminin is a key mediator in the differentiation and formation of the skeletal neuromuscular junction. Loss of β2-laminin results in significant structural and functional aberrations such as decreased number of active zones and reduced spontaneous release of transmitter. In vitro β2-laminin has been shown to bind directly to the pore forming subunit of P/Q-type voltage-gated calcium channels (VGCCs). Neurotransmission is initially mediated by N-type VGCCs, but by postnatal day 18 switches to P/Q-type VGCC dominance. The present study investigated the changes in neurotransmission during the switch from N- to P/Q-type VGCC-mediated transmitter release at β2-laminin-deficient junctions. Analysis of the relationship between quantal content and extracellular calcium concentrations demonstrated a decrease in the calcium sensitivity, but no change in calcium dependence at β2-laminin-deficient junctions. Electrophysiological studies on VGCC sub-types involved in transmitter release indicate N-type VGCCs remain the primary mediator of transmitter release at matured β2-laminin-deficient junctions. Immunohistochemical analyses displayed irregularly shaped and immature β2-laminin-deficient neuromuscular junctions when compared to matured wild-type junctions. β2-laminin-deficient junctions also maintained the presence of N-type VGCC clustering within the presynaptic membrane, which supported the functional findings of the present study. We conclude that β2-laminin is a key regulator in development of the NMJ, with its loss resulting in reduced transmitter release due to decreased calcium sensitivity stemming from a failure to switch from N- to P/Q-type VGCC-mediated synaptic transmission.
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Affiliation(s)
- Kirat K Chand
- School of Biomedical Sciences, The University of Queensland, St Lucia, 4067, Australia
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Differential effects of amphetamine and GBR-12909 on orolingual motor function in young vs aged F344/BN rats. Psychopharmacology (Berl) 2014; 231:4695-701. [PMID: 24923981 PMCID: PMC4301607 DOI: 10.1007/s00213-014-3620-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
RATIONALE Orolingual motor deficits, such as dysarthria and dysphagia, contribute to increased morbidity and mortality in the elderly. In preclinical studies, we and others have reported age-related decreases in tongue motility in both F344 and F344/BN rats. The fact that these deficits are associated with nigrostriatal dopamine (DA), tissue measures suggest that increasing dopamine function might normalize tongue motility. OBJECTIVE The purpose of the current study was to determine whether two indirect dopamine agonists with locomotor-enhancing effects, d-amphetamine (amphetamine; 1 and 2 mg/kg) and GBR-12909 (5, 10, and 20 mg/kg), can improve tongue motility in aged F344/BN rats. METHODS Young (6 months) and aged (30 months) F344/BN rats licked water from an isometric force disc so that tongue motility (licks/second) and tongue force could be measured as a function of age and drug dose. RESULTS Consistent with our previous studies, tongue force was greater and tongue motility was lower in the aged group. Tongue motility was increased by amphetamine but not by GBR-12909. Amphetamine decreased peak tongue force, primarily in the young group. GBR-12909 did not affect tongue force. GBR-12909 increased the number of licks/session in the young group but not in the aged group, while amphetamine increased this measure in both groups. CONCLUSION These results demonstrate differential effects of these drugs on orolingual motor function and suggest that blocking DA uptake is insufficient to increase tongue motility in aging.
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Gonzalez-Freire M, de Cabo R, Studenski SA, Ferrucci L. The Neuromuscular Junction: Aging at the Crossroad between Nerves and Muscle. Front Aging Neurosci 2014; 6:208. [PMID: 25157231 PMCID: PMC4127816 DOI: 10.3389/fnagi.2014.00208] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/25/2014] [Indexed: 01/19/2023] Open
Abstract
Aging is associated with a progressive loss of muscle mass and strength and a decline in neurophysiological functions. Age-related neuromuscular junction (NMJ) plays a key role in musculoskeletal impairment that occurs with aging. However, whether changes in the NMJ precede or follow the decline of muscle mass and strength remains unresolved. Many factors such as mitochondrial dysfunction, oxidative stress, inflammation, changes in the innervation of muscle fibers, and mechanical properties of the motor units probably perform an important role in NMJ degeneration and muscle mass and strength decline in late life. This review addresses the primary events that might lead to NMJ dysfunction with aging, including studies on biomarkers, signaling pathways, and animal models. Interventions such as caloric restriction and exercise may positively affect the NMJ through this mechanism and attenuate the age-related progressive impairment in motor function.
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Affiliation(s)
- Marta Gonzalez-Freire
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA
| | - Stephanie A Studenski
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, Intramural Research Program, National Institutes of Health , Baltimore, MD , USA ; Longitudinal Studies Section, Baltimore Longitudinal Study of Aging, National Institute on Aging, National Institutes of Health , Baltimore, MD , USA
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Petralia RS, Mattson MP, Yao PJ. Communication breakdown: the impact of ageing on synapse structure. Ageing Res Rev 2014; 14:31-42. [PMID: 24495392 PMCID: PMC4094371 DOI: 10.1016/j.arr.2014.01.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 12/16/2013] [Accepted: 01/23/2014] [Indexed: 01/13/2023]
Abstract
Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences.
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Affiliation(s)
- Ronald S Petralia
- Advanced Imaging Core, NIDCD/NIH, Bethesda, MD 20892, United States.
| | - Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, United States
| | - Pamela J Yao
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, United States.
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Schmitz F. Presynaptic [Ca(2+)] and GCAPs: aspects on the structure and function of photoreceptor ribbon synapses. Front Mol Neurosci 2014; 7:3. [PMID: 24567702 PMCID: PMC3915146 DOI: 10.3389/fnmol.2014.00003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/15/2014] [Indexed: 12/21/2022] Open
Abstract
Changes in intracellular calcium ions [Ca2+] play important roles in photoreceptor signaling. Consequently, intracellular [Ca2+] levels need to be tightly controlled. In the light-sensitive outer segments (OS) of photoreceptors, Ca2+ regulates the activity of retinal guanylate cyclases thus playing a central role in phototransduction and light-adaptation by restoring light-induced decreases in cGMP. In the synaptic terminals, changes of intracellular Ca2+ trigger various aspects of neurotransmission. Photoreceptors employ tonically active ribbon synapses that encode light-induced, graded changes of membrane potential into modulation of continuous synaptic vesicle exocytosis. The active zones of ribbon synapses contain large electron-dense structures, synaptic ribbons, that are associated with large numbers of synaptic vesicles. Synaptic coding at ribbon synapses differs from synaptic coding at conventional (phasic) synapses. Recent studies revealed new insights how synaptic ribbons are involved in this process. This review focuses on the regulation of [Ca2+] in presynaptic photoreceptor terminals and on the function of a particular Ca2+-regulated protein, the neuronal calcium sensor protein GCAP2 (guanylate cyclase-activating protein-2) in the photoreceptor ribbon synapse. GCAP2, an EF-hand-containing protein plays multiple roles in the OS and in the photoreceptor synapse. In the OS, GCAP2 works as a Ca2+-sensor within a Ca2+-regulated feedback loop that adjusts cGMP levels. In the photoreceptor synapse, GCAP2 binds to RIBEYE, a component of synaptic ribbons, and mediates Ca2+-dependent plasticity at that site. Possible mechanisms are discussed.
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Affiliation(s)
- Frank Schmitz
- Department of Neuroanatomy, Institute for Anatomy and Cell Biology, Medical School Homburg/Saar, Saarland University Saarland, Germany
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Nishimune H, Stanford JA, Mori Y. Role of exercise in maintaining the integrity of the neuromuscular junction. Muscle Nerve 2013; 49:315-24. [PMID: 24122772 DOI: 10.1002/mus.24095] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2013] [Indexed: 01/16/2023]
Abstract
Physical activity plays an important role in preventing chronic disease in adults and the elderly. Exercise has beneficial effects on the nervous system, including at the neuromuscular junction (NMJ). Exercise causes hypertrophy of NMJs and improves recovery from peripheral nerve injuries, whereas decreased physical activity causes degenerative changes in NMJs. Recent studies have begun to elucidate molecular mechanisms underlying the beneficial effects of exercise. These mechanisms involve Bassoon, neuregulin-1, peroxisome proliferator-activated receptor gamma coactivator 1α, insulin-like growth factor-1, glial cell line-derived neurotrophic factor, neurotrophin 4, Homer, and nuclear factor of activated T cells c1. For example, NMJ denervation and active zone decreases have been observed in aged NMJs, but these age-dependent degenerative changes can be ameliorated by exercise. In this review we assess the effects of exercise on the maintenance and regeneration of NMJs and highlight recent insights into the molecular mechanisms underlying these exercise effects.
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Affiliation(s)
- Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, 3901 Rainbow Boulevard, MS 3051, HLSIC Room 2073, Kansas City, Kansas, 66160, USA
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Hirst TC, Ribchester RR. Segmentation of the mouse fourth deep lumbrical muscle connectome reveals concentric organisation of motor units. J Physiol 2013; 591:4859-75. [PMID: 23940381 DOI: 10.1113/jphysiol.2013.258087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Connectomic analysis of the nervous system aims to discover and establish principles that underpin normal and abnormal neural connectivity and function. Here we performed image analysis of motor unit connectivity in the fourth deep lumbrical muscle (4DL) of mice, using transgenic expression of fluorescent protein in motor neurones as a morphological reporter. We developed a method that accelerated segmentation of confocal image projections of 4DL motor units, by applying high resolution (63×, 1.4 NA objective) imaging or deconvolution only where either proved necessary, in order to resolve axon crossings that produced ambiguities in the correct assignment of axon terminals to identified motor units imaged at lower optical resolution (40×, 1.3 NA). The 4DL muscles contained between 4 and 9 motor units and motor unit sizes ranged in distribution from 3 to 111 motor nerve terminals per unit. Several structural properties of the motor units were consistent with those reported in other muscles, including suboptimal wiring length and distribution of motor unit size. Surprisingly, however, small motor units were confined to a region of the muscle near the nerve entry point, whereas their larger counterparts were progressively more widely dispersed, suggesting a previously unrecognised form of segregated motor innervation in this muscle. We also found small but significant differences in variance of motor endplate length in motor units, which correlated weakly with their motor unit size. Thus, our connectomic analysis has revealed a pattern of concentric innervation that may perhaps also exist in other, cylindrical muscles that have not previously been thought to show segregated motor unit organisation. This organisation may be the outcome of competition during postnatal development based on intrinsic neuronal differences in synaptic size or synaptic strength that generates a territorial hierarchy in motor unit size and disposition.
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Affiliation(s)
- Theodore C Hirst
- R. R. Ribchester: Euan Macdonald Centre for Motor Neurone Disease Research, Centre for Integrative Physiology, The University of Edinburgh, Edinburgh EH8 9XD, UK.
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Zabouri N, Haverkamp S. Calcium channel-dependent molecular maturation of photoreceptor synapses. PLoS One 2013; 8:e63853. [PMID: 23675510 PMCID: PMC3652833 DOI: 10.1371/journal.pone.0063853] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 04/08/2013] [Indexed: 01/08/2023] Open
Abstract
Several studies have shown the importance of calcium channels in the development and/or maturation of synapses. The CaV1.4(α1F) knockout mouse is a unique model to study the role of calcium channels in photoreceptor synapse formation. It features abnormal ribbon synapses and aberrant cone morphology. We investigated the expression and targeting of several key elements of ribbon synapses and analyzed the cone morphology in the CaV1.4(α1F) knockout retina. Our data demonstrate that most abnormalities occur after eye opening. Indeed, scaffolding proteins such as Bassoon and RIM2 are properly targeted at first, but their expression and localization are not maintained in adulthood. This indicates that either calcium or the CaV1.4 channel, or both are necessary for the maintenance of their normal expression and distribution in photoreceptors. Other proteins, such as Veli3 and PSD-95, also display abnormal expression in rods prior to eye opening. Conversely, vesicle related proteins appear normal. Our data demonstrate that the CaV1.4 channel is important for maintaining scaffolding proteins in the ribbon synapse but less vital for proteins related to vesicular release. This study also confirms that in adult retinae, cones show developmental features such as sprouting and synaptogenesis. Overall we present evidence that in the absence of the CaV1.4 channel, photoreceptor synapses remain immature and are unable to stabilize.
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Affiliation(s)
- Nawal Zabouri
- Neuroanatomy, Max-Planck-Institute for Brain Research, Frankfurt am Main, Germany.
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Nishimune H. Active zones of mammalian neuromuscular junctions: formation, density, and aging. Ann N Y Acad Sci 2013; 1274:24-32. [PMID: 23252894 DOI: 10.1111/j.1749-6632.2012.06836.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Presynaptic active zones are synaptic vesicle release sites that play essential roles in the function and pathology of mammalian neuromuscular junctions (NMJs). The molecular mechanisms of active zone organization use presynaptic voltage-dependent calcium channels (VDCCs) in NMJs as scaffolding proteins. VDCCs interact extracellularly with the muscle-derived synapse organizer, laminin β2 and interact intracellularly with active zone-specific proteins, such as Bassoon, CAST/Erc2/ELKS2alpha, ELKS, Piccolo, and RIMs. These molecular mechanisms are supported by studies in P/Q- and N-type VDCCs double-knockout mice, and they are consistent with the pathological conditions of Lambert-Eaton myasthenic syndrome and Pierson syndrome, which are caused by autoantibodies against VDCCs or by a laminin β2 mutation. During normal postnatal maturation, NMJs maintain the density of active zones, while NMJs triple their size. However, active zones become impaired during aging. Propitiously, muscle exercise ameliorates the active zone impairment in aged NMJs, which suggests the potential for therapeutic strategies.
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Affiliation(s)
- Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas Medical School, Kansas City, 66160, USA.
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