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neuromuscular junction physiology

Marco Morsch, Dario A Protti, Delfine Cheng, Filip Braet, Roger S Chung, Stephen W Reddel, William D Phillips
Cannabinoids exert dynamic control over many physiological processes including memory formation, cognition and pain perception. In the central nervous system endocannabinoids mediate negative feedback of quantal transmitter release following postsynaptic depolarization. The influence of cannabinoids in the peripheral nervous system is less clear and might have broad implications for the therapeutic application of cannabinoids. We report a novel cannabinoid effect upon the mouse neuromuscular synapse: acutely increasing synaptic vesicle volume and raising the quantal amplitudes...
March 16, 2018: Scientific Reports
Navaneetha Santhanam, Lee Kumanchik, Xiufang Guo, Frank Sommerhage, Yunqing Cai, Max Jackson, Candace Martin, George Saad, Christopher W McAleer, Ying Wang, Andrea Lavado, Christopher J Long, James J Hickman
There are currently no functional neuromuscular junction (hNMJ) systems composed of human cells that could be used for drug evaluations or toxicity testing in vitro. These systems are needed to evaluate NMJs for diseases such as amyotrophic lateral sclerosis, spinal muscular atrophy or other neurodegenerative diseases or injury states. There are certainly no model systems, animal or human, that allows for isolated treatment of motoneurons or muscle capable of generating dose response curves to evaluate pharmacological activity of these highly specialized functional units...
February 27, 2018: Biomaterials
Kazuyoshi Itoh, Yoshihiro Akimoto, Shu Kondo, Tomomi Ichimiya, Kazuhiro Aoki, Michael Tiemeyer, Shoko Nishihara
T antigen (Galβ1-3GalNAcα1-Ser/Thr) is an evolutionary-conserved mucin-type core 1 glycan structure in animals synthesized by core 1 β1,3-galactosyltrasferase 1 (C1GalT1). Previous studies showed that T antigen produced by Drosophila C1GalT1 (dC1GalT1) was expressed in various tissues and dC1GalT1 loss in larvae led to various defects, including decreased number of circulating hemocytes, hyper-differentiation of hematopoietic stem cells in lymph glands, malformation of the central nervous system, mislocalization of neuromuscular junction (NMJ) boutons, and ultrastructural abnormalities in NMJs and muscle cells...
February 27, 2018: Developmental Biology
Mikako Ito, Kinji Ohno
Endplate acetylcholinesterase (AChE) deficiency is a form of congenital myasthenic syndrome (CMS) caused by mutations in COLQ, which encodes collagen Q (ColQ). ColQ is an extracellular matrix (ECM) protein that anchors AChE to the synaptic basal lamina. Biglycan, encoded by BGN, is another ECM protein that binds to the dystrophin-associated protein complex (DAPC) on skeletal muscle, which links the actin cytoskeleton and ECM proteins to stabilize the sarcolemma during repeated muscle contractions. Upregulation of biglycan stabilizes the DPAC...
February 20, 2018: Matrix Biology: Journal of the International Society for Matrix Biology
Xiaomin Xing, Chun-Fang Wu
GCaMP is an optogenetic Ca2+ sensor widely used for monitoring neuronal activities but the precise physiological implications of GCaMP signals remain to be further delineated among functionally distinct synapses. The Drosophila neuromuscular junction (NMJ), a powerful genetic system for studying synaptic function and plasticity, consists of tonic and phasic glutamatergic and modulatory aminergic motor terminals of distinct properties. We report a first simultaneous imaging and electric recording study to directly contrast the frequency characteristics of GCaMP signals of the three synapses for physiological implications...
January 2018: ENeuro
Jorge Azpurua, Rebekah E Mahoney, Benjamin A Eaton
The neuromuscular junction (NMJ) is responsible for transforming nervous system signals into motor behavior and locomotion. In the fruit fly Drosophila melanogaster, an age-dependent decline in motor function occurs, analogous to the decline experienced in mice, humans, and other mammals. The molecular and cellular underpinnings of this decline are still poorly understood. By specifically profiling the transcriptome of Drosophila motor neurons across age using custom microarrays, we found that the expression of the matrix metalloproteinase 1 (dMMP1) gene reproducibly increased in motor neurons in an age-dependent manner...
February 7, 2018: Aging Cell
Claire Legay
The neuromuscular junction (NMJ) is a cholinergic synapse in vertebrates. This synapse connects motoneurons to muscles and is responsible for muscle contraction, a physiological process that is essential for survival. A key factor for the normal functioning of this synapse is the regulation of acetylcholine (ACh) levels in the synaptic cleft. This is ensured by acetylcholinesterase (AChE), which degrades ACh. A number of mutations in synaptic genes expressed in motoneurons or muscle cells have been identified and are causative for a class of neuromuscular diseases called congenital myasthenic syndromes (CMSs)...
February 2018: Annals of the New York Academy of Sciences
Vicente Valenzuela, Melissa Nassif, Claudio Hetz
In recent years, the role of autophagy in the pathogenesis of most neurodegenerative diseases has transited into a limbo of protective or detrimental effects. Genetic evidence indicates that mutations in autophagy-regulatory genes can result in the occurrence of amyotrophic lateral sclerosis (ALS), suggesting a physiological role of the pathway to motoneuron function. However, experimental manipulation of autophagy in ALS models led to conflicting results depending on the intervention strategy and the disease model used...
February 1, 2018: Autophagy
Rui Chen, Daniel R Swale
A complete understanding of the physiological pathways critical for proper function of the insect nervous system is still lacking. The recent development of potent and selective small-molecule modulators of insect inward rectifier potassium (Kir) channels has enabled the interrogation of the physiological role and toxicological potential of Kir channels within various insect tissue systems. Therefore, we aimed to highlight the physiological and functional role of neural Kir channels the central nervous system, muscular system, and neuromuscular system through pharmacological and genetic manipulations...
January 25, 2018: Scientific Reports
Neil A Kelly, Kelley G Hammond, C Scott Bickel, Samuel T Windham, S Craig Tuggle, Marcas M Bamman
Aging muscle atrophy is in part a neurodegenerative process revealed by denervation-reinnervation events leading to motor unit remodeling (i.e. myofiber type grouping). However, this process and its physiologic relevance are poorly understood, as is the wide-ranging heterogeneity among aging humans. Here, we attempted to address the: (i) relation between myofiber type grouping and molecular regulators of neuromuscular junction (NMJ) stability; (ii) impact of motor unit remodeling on recruitment during submaximal contractions; (iii) prevalence and impact of motor unit remodeling in Parkinson's disease (PD), an age-related neurodegenerative disease; and (iv) influence of resistance exercise training (RT) on regulators of motor unit remodeling...
December 21, 2017: Journal of Applied Physiology
Rozita Laghaei, Jun Ma, Tyler Tarr, Anne E Homan, Lauren Kelly, Megha Tilvawala, Blake Vuocolo, Harini Rajasekaran, Stephen D Meriney, Markus Dittrich
We have investigated the impact of transmitter release site (active zone; AZ) structure on synaptic function by physically rearranging the individual AZ elements in a previously published frog neuromuscular junction (NMJ) AZ model into the organization observed in a mouse NMJ AZ. We have used this strategy, purposefully without changing the properties of AZ elements between frog and mouse models (even though there are undoubtedly differences between frog and mouse AZ elements in vivo), to directly test how structure influences function at the level of an AZ...
December 27, 2017: Journal of Neurophysiology
Dengyun Ge, Nickolas Anastasios Lavidis
Amphibian neuromuscular junctions become relatively more silent during the dry-winter season in Australia. Endogenous opioid peptides play an important role in the regulation of the physiological functions of active and dormant vertebrates. Previous findings suggest that dynorphin-A is more potent than other opiates in decreasing evoked neurotransmission in amphibian neuromuscular junctions. Dynorphin-A has been shown not to alter the amplitude or the frequency of spontaneous quantal neurotransmitter release...
January 17, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Nadine Ehmann, David Owald, Robert J Kittel
In a constantly changing environment, neuronal circuits need to be updated and adjusted to elicit directed actions. Synaptic plasticity plays an important role in modulating such globally and locally acting networks. The active zone (AZ) is a protein-rich compartment of chemical synapses, where precisely orchestrated molecular interactions control synaptic vesicle (SV) fusion with the presynaptic membrane. The subsequent release of neurotransmitter substances onto postsynaptic receptor fields forms the basis of neuronal communication...
December 16, 2017: Neuroscience Research
Marine Pons, Claire Soulard, Laurent Soustelle, Marie-Laure Parmentier, Yves Grau, Sophie Layalle
The function of the nervous system in complex animals is reflected by the achievement of specific behaviors. For years in Drosophila , both simple and complex behaviors have been studied and their genetic bases have emerged. The neuromuscular junction is maybe one of the prototypal simplest examples. A motor neuron establishes synaptic connections on its muscle cell target and elicits behavior: the muscle contraction. Different muscles in adult fly are related to specific behaviors. For example, the thoracic muscles are associated with flight and the leg muscles are associated with locomotion...
2017: Frontiers in Cellular Neuroscience
Lei Li, Wen-Cheng Xiong, Lin Mei
Synapses, the fundamental unit in neuronal circuits, are critical for learning and memory, perception, thinking, and reaction. The neuromuscular junction (NMJ) is a synapse formed between motoneurons and skeletal muscle fibers that is covered by Schwann cells (SCs). It is essential for controlling muscle contraction. NMJ formation requires intimate interactions among motoneurons, muscles, and SCs. Deficits in NMJ formation and maintenance cause neuromuscular disorders, including congenital myasthenic syndrome and myasthenia gravis...
February 10, 2018: Annual Review of Physiology
Holger Greschik, Delphine Duteil, Nadia Messaddeq, Dominica Willmann, Laura Arrigoni, Manuela Sum, Manfred Jung, Daniel Metzger, Thomas Manke, Thomas Günther, Roland Schüle
While several studies correlated increased expression of the histone code reader Spin1 with tumor formation or growth, little is known about physiological functions of the protein. We generated Spin1M5 mice with ablation of Spin1 in myoblast precursors using the Myf5-Cre deleter strain. Most Spin1M5 mice die shortly after birth displaying severe sarcomere disorganization and necrosis. Surviving Spin1M5 mice are growth-retarded and exhibit the most prominent defects in soleus, tibialis anterior, and diaphragm muscle...
November 23, 2017: Cell Death & Disease
Kayly M Lembke, David B Morton
Amyotrophic lateral sclerosis (ALS) is the most common adult onset motor neurodegenerative disease. The cause of the disease remains obscure, and as such there is no effective treatment or cure. Amyotrophic lateral sclerosis and other neurodegenerative diseases are frequently characterized by dysfunction of the RNA-binding protein, TDP-43. Using model systems to understand the mechanisms underlying TDP-43 dysfunction should accelerate identification of therapeutic targets. A recent report has shown that motor defects caused by the deletion of the Drosophila TDP-43 ortholog, tbph , are not driven by changes in the physiology at the neuromuscular junction...
2017: Journal of Experimental Neuroscience
Sophie Nicole, Yoshiteru Azuma, Stéphanie Bauché, Bruno Eymard, Hanns Lochmüller, Clarke Slater
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models...
2017: Journal of Neuromuscular Diseases
Hongyu Ruan, Atsushi Ueda, Xiaomin Xing, Xuxuan Wan, Benjamin Strub, Spencer Mukai, Kaan Certel, David Green, Kyle Belozerov, Wei-Dong Yao, Wayne Johnson, Jim Jung-Ching Lin, Arthur J Hilliker, Chun-Fang Wu
Our earlier genetic screen uncovered a paraquat-sensitive leg-shaking mutant quiver(1) (qvr(1)), whose gene product interacts with the Shaker (Sh) K(+) channel. We also mapped the qvr locus to EY04063 and noticed altered day-night activity patterns in these mutants. Such circadian behavioral defects were independently reported by another group, who employed the qvr(1) allele we supplied them, and attributed the extreme restless phenotype of EY04063 to the qvr gene. However, their report adopted a new noncanonical gene name sleepless (sss) for qvr...
November 9, 2017: Journal of Neurogenetics
Céline Desseille, Séverine Deforges, Olivier Biondi, Léo Houdebine, Domenico D'amico, Antonin Lamazière, Cédric Caradeuc, Gildas Bertho, Gaëlle Bruneteau, Laure Weill, Jean Bastin, Fatima Djouadi, François Salachas, Philippe Lopes, Christophe Chanoine, Charbel Massaad, Frédéric Charbonnier
Amyotrophic Lateral Sclerosis is an adult-onset neurodegenerative disease characterized by the specific loss of motor neurons, leading to muscle paralysis and death. Although the cellular mechanisms underlying amyotrophic lateral sclerosis (ALS)-induced toxicity for motor neurons remain poorly understood, growing evidence suggest a defective energetic metabolism in skeletal muscles participating in ALS-induced motor neuron death ultimately destabilizing neuromuscular junctions. In the present study, we report that a specific exercise paradigm, based on a high intensity and amplitude swimming exercise, significantly improves glucose metabolism in ALS mice...
2017: Frontiers in Molecular Neuroscience
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