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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
Huan Yi, Bingbing Xie, Ben Liu, Xuan Wang, Li Xu, Jia Liu, Min Li, Xiufeng Zhong, Fuhua Peng
Induced pluripotent stem cells (iPSCs) have provided new opportunities for motor neuron disease (MND) modeling, drug screening, and cellular therapeutic development. Among the various types of iPSCs, urine-derived iPSCs have become a promising source of stem cells because they can be safely and noninvasively isolated and easily reprogrammed. Here, for the first time, we differentiated urine-derived iPSCs (urine-iPSCs) into motor neurons (MNs) and compared the capacity of urine-iPSCs and cord-blood-derived iPSCs (B-iPSCs) to differentiate into MNs...
2018: Stem Cells International
Shruti Thapliyal, Amruta Vasudevan, Yongming Dong, Jihong Bai, Sandhya P Koushika, Kavita Babu
The C. elegans ortholog of mammalian calsyntenins, CASY-1, is an evolutionarily conserved type-I transmembrane protein that is highly enriched in the nervous system. Mammalian calsyntenins are strongly expressed at inhibitory synapses, but their role in synapse development and function is still elusive. Here, we report a crucial role for CASY-1 in regulating GABAergic synaptic transmission at the C. elegans neuromuscular junction (NMJ). The shorter isoforms of CASY-1; CASY-1B and CASY-1C, express and function in GABA motor neurons where they regulate GABA neurotransmission...
March 12, 2018: PLoS Genetics
Lilian A Martinez Carrera, Elke Gabriel, Colin Donohoe, Irmgard Hölker, Aruljothi Mariappan, Markus Storbeck, Mirka Uhlirova, Jay Gopalakrishnan, Brunhilde Wirth
BICD2 encodes a highly conserved motor adaptor protein that regulates the dynein-dynactin complex in different cellular processes. Heterozygous mutations in BICD2 cause autosomal dominant lower extremity-predominant spinal muscular atrophy-2 (SMALED2). Although, various BICD2 mutations have been shown to alter interactions with different binding partners or the integrity of the Golgi apparatus, the specific pathological effects of BICD2 mutations underlying SMALED2 remain elusive. Here, we show that the fibroblasts derived from individuals with SMALED2 exhibit stable microtubules...
March 8, 2018: Human Molecular Genetics
Stuart J Grice, James N Sleigh, M Zameel Cader
Dominant mutations in GARS , encoding the ubiquitous enzyme glycyl-tRNA synthetase (GlyRS), cause peripheral nerve degeneration and Charcot-Marie-Tooth disease type 2D (CMT2D). This genetic disorder exemplifies a recurring paradigm in neurodegeneration, in which mutations in essential genes cause selective degeneration of the nervous system. Recent evidence suggests that the mechanism underlying CMT2D involves extracellular neomorphic binding of mutant GlyRS to neuronally-expressed proteins. Consistent with this, our previous studies indicate a non-cell autonomous mechanism, whereby mutant GlyRS is secreted and interacts with the neuromuscular junction (NMJ)...
2018: Frontiers in Molecular Neuroscience
Ryo Ueta, Yuji Yamanashi
The neuromuscular junction(NMJ)is the synapse between a motor neuron and the skeletal muscle that is essential for muscle contraction. Impairments at the NMJ lead to neuromuscular-transmission pathologies characterized by fatigable muscle weakness. Muscle-specific receptor tyrosine kinase MuSK plays key roles in NMJ formation. Over the past decade, studies examining the NMJ formation signals have identified molecules involved in the signaling pathways and have promoted a better understanding of characteristic molecular mechanisms for MuSK activation...
2018: Clinical Calcium
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
Tae Chung, Yanli Tian, Jeremy Walston, Ahmet Hoke
OBJECTIVE: Age-associated skeletal muscle weakness is a major contributing factor to an increased late life mortality and morbidity, but its neurobiology is poorly understood. Previously, we provided histological evidence of dying-back axonal degeneration of motor neurons and denervation of neuromuscular junctions (NMJ) in age-associated muscle weakness. Given this, we aim to evaluate the relation between impaired neuromuscular transmission and various aspects of age-associated muscle weakness...
March 1, 2018: American Journal of Physical Medicine & Rehabilitation
Jia Yu, Chen Lai, Hoon Shim, Chengsong Xie, Lixin Sun, Cai-Xia Long, Jinhui Ding, Yan Li, Huaibin Cai
BACKGROUND: Dynactin p150Glued , the largest subunit of the dynactin macromolecular complex, binds to both microtubules and tubulin dimers through the N-terminal cytoskeleton-associated protein and glycine-rich (CAP-Gly) and basic domains, and serves as an anti-catastrophe factor in stabilizing microtubules in neurons. P150Glued also initiates dynein-mediated axonal retrograde transport. Multiple missense mutations at the CAP-Gly domain of p150Glued are associated with motor neuron diseases and other neurodegenerative disorders, further supporting the importance of microtubule domains (MTBDs) in p150Glued functions...
March 1, 2018: Molecular Neurodegeneration
Shruti Thapliyal, Shruthi Ravindranath, Kavita Babu
Locomotion is one of the most prominent behaviors in the nematode Caenorhabditis elegans. Neuronal circuits that ultimately produce coordinated dorso-ventral sinusoidal bends mediate this behavior. Synchronized locomotion requires an intricate balance between excitation and inhibition at the neuromuscular junctions (NMJ), the complex cellular and molecular mechanisms of which are not fully understood. Here, we describe the role of a cell adhesion molecule CASY-1, which functions to maintain this balance at the NMJ...
February 23, 2018: Genetics
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
Abhirami K Iyer, Kathryn J Jones, Virginia M Sanders, Chandler L Walker
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of lower and upper motor neurons (MN) leading to muscle weakness, paralysis and eventually death. Although a highly varied etiology results in ALS, it broadly manifests itself as sporadic and familial forms that have evident similarities in clinical symptoms and disease progression. There is a tremendous amount of knowledge on molecular mechanisms leading to loss of MNs and neuromuscular junctions (NMJ) as major determinants of disease onset, severity and progression in ALS...
February 23, 2018: International Journal of Molecular Sciences
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
Grace McMacken, Dan Cox, Andreas Roos, Juliane Müller, Roger Whittaker, Hanns Lochmüller
Inherited defects of the neuromuscular junction (NMJ) comprise an increasingly diverse range of disorders, termed congenital myasthenic syndromes (CMS). Therapies acting on the sympathetic nervous system, including the selective β2 adrenergic agonist salbutamol and the α and β adrenergic agonist ephedrine, have become standard treatment for several types of CMS. However, the mechanism of the therapeutic effect of sympathomimetics in these disorders is not understood. Here, we examined the effect of salbutamol on NMJ development using zebrafish with deficiency of the key postsynaptic proteins Dok-7 and MuSK...
February 16, 2018: Human Molecular Genetics
Marina Boido, Elena De Amicis, Valeria Valsecchi, Marco Trevisan, Ugo Ala, Markus A Ruegg, Stefan Hettwer, Alessandro Vercelli
Spinal muscular atrophy (SMA) is a pediatric genetic disease, characterized by motor neuron (MN) death, leading to progressive muscle weakness, respiratory failure, and, in the most severe cases, to death. Abnormalities at the neuromuscular junction (NMJ) have been reported in SMA, including neurofilament (NF) accumulation at presynaptic terminals, immature and smaller than normal endplates, reduced transmitter release, and, finally, muscle denervation. Here we have studied the role of agrin in SMAΔ7 mice, the experimental model of SMAII...
2018: Frontiers in Cellular Neuroscience
Rebecca J Wilson, Joshua C Drake, Di Cui, Bevan M Lewellen, Carleigh C Fisher, Mei Zhang, David F Kashatus, Lisa A Palmer, Michael P Murphy, Zhen Yan
Deterioration of neuromuscular junction (NMJ) integrity and function is causal to muscle atrophy and frailty, ultimately hindering quality of life and increasing the risk of death. In particular, NMJ is vulnerable to ischemia reperfusion (IR) injury when blood flow is restricted followed by restoration. However, little is known about the underlying mechanism(s) and hence the lack of effective interventions. New evidence suggests that mitochondrial oxidative stress plays a causal role in IR injury, which can be precluded by enhancing mitochondrial protein S-nitrosation (SNO)...
February 9, 2018: Free Radical Biology & Medicine
Jianwen Wang, Yatao Xiao, Kejing Zhang, Benyan Luo, Chengyong Shen
The neuromuscular junction (NMJ) is a peripheral synapse between motor neurons and skeletal muscle fibers that controls muscle contraction. The NMJ is the target of various disorders including myasthenia gravis (MG), an autoimmune disease in which auto-antibodies (auto-Abs) attack the synapse, and thus cause muscle weakness in patients. There are multiple auto-Abs in the MG patient sera, but not all the Abs are proven to be pathogenic, which increases the difficulties in clinical diagnoses and treatments. To establish the causative roles of auto-Abs in MG pathogenesis, the experimental autoimmune MG (EAMG) induced by the active immunization of auto-antigens (auto-Ags) or the passive transfer of auto-Abs is required...
February 5, 2018: Neuroscience
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
Cinzia Pisani, Georgios Strimpakos, Francesca Gabanella, Maria Grazia Di Certo, Annalisa Onori, Cinzia Severini, Siro Luvisetto, Stefano Farioli-Vecchioli, Irene Carrozzo, Antonio Esposito, Tamara Canu, Elisabetta Mattei, Nicoletta Corbi, Claudio Passananti
Up-regulation of the dystrophin-related gene utrophin represents a promising therapeutic strategy for the treatment of Duchenne Muscular Dystrophy (DMD). In order to re-program the utrophin expression level in muscle, we engineered artificial zinc finger transcription factors (ZF-ATFs) that target the utrophin "A" promoter. We have previously shown that the ZF-ATF "Jazz", either by transgenic manipulation or by systemic adeno-associated viral delivery, induces significant rescue of muscle function in dystrophic "mdx" mice...
January 30, 2018: Biochimica et Biophysica Acta
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
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