scholarly journals Tenectin recruits integrin to stabilize bouton architecture and regulate vesicle release at the Drosophila neuromuscular junction

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Qi Wang ◽  
Tae Hee Han ◽  
Peter Nguyen ◽  
Michal Jarnik ◽  
Mihaela Serpe
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Synaptic Cleft ◽  
Membrane Skeleton ◽  
Biologically Active ◽  
Striated Muscles ◽  
Local Engagement ◽  
Synaptic Junctions ◽  
Synaptic Boutons ◽  
And Function

Assembly, maintenance and function of synaptic junctions depend on extracellular matrix (ECM) proteins and their receptors. Here we report that Tenectin (Tnc), a Mucin-type protein with RGD motifs, is an ECM component required for the structural and functional integrity of synaptic specializations at the neuromuscular junction (NMJ) in Drosophila. Using genetics, biochemistry, electrophysiology, histology and electron microscopy, we show that Tnc is secreted from motor neurons and striated muscles and accumulates in the synaptic cleft. Tnc selectively recruits αPS2/βPS integrin at synaptic terminals, but only the cis Tnc/integrin complexes appear to be biologically active. These complexes have distinct pre- and postsynaptic functions, mediated at least in part through the local engagement of the spectrin-based membrane skeleton: the presynaptic complexes control neurotransmitter release, while postsynaptic complexes ensure the size and architectural integrity of synaptic boutons. Our study reveals an unprecedented role for integrin in the synaptic recruitment of spectrin-based membrane skeleton.

scholarly journals Neto-α controls synapse organization and homeostasis at the Drosophila neuromuscular junction

2019 ◽  
Author(s):  
Tae Hee Han ◽  
Rosario Vicidomini ◽  
Cathy Isaura Ramos ◽  
Qi Wang ◽  
Peter Nguyen ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Neurotransmitter Release ◽  
Cell Biology ◽  
Expression Patterns ◽  
Dependent Manner ◽  
Independent Function ◽  
Postsynaptic Receptors ◽  
Auxiliary Protein ◽  
And Function

SummaryGlutamate receptor auxiliary proteins control receptor distribution and function, ultimately controlling synapse assembly, maturation and plasticity. At the Drosophila neuromuscular junction (NMJ), a synapse with both pre- and post-synaptic kainate-type glutamate receptors (KARs), we show that the auxiliary protein Neto evolved functionally distinct isoforms to modulate synapse development and homeostasis. Using genetics, cell biology and electrophysiology we demonstrate that Neto-α functions on both sides of the NMJ. In muscle, Neto-α limits the size of the postsynaptic receptors field. In motor neurons, Neto-α controls neurotransmitter release in a KAR-dependent manner. Furthermore, Neto-α is both required and sufficient for the presynaptic increase in neurotransmitter release in response to reduced postsynaptic sensitivity. This KAR-independent function of Neto-α is involved in activity-induced cytomatrix remodeling. We propose that Drosophila ensured NMJ functionality by acquiring two Neto isoforms with differential expression patterns and activities.

scholarly journals ARIA is concentrated in the synaptic basal lamina of the developing chick neuromuscular junction.

1995 ◽  
Vol 130 (6) ◽  
pp. 1423-1434 ◽  
Author(s):  
A D Goodearl ◽  
A G Yee ◽  
A W Sandrock ◽  
G Corfas ◽  
G D Fischbach
Keyword(s):  
Neuromuscular Junction ◽  
Basal Lamina ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Primary Cultures ◽  
Cholinergic Neurons ◽  
Synaptic Cleft ◽  
Motor Axons ◽  
Amino Terminal

ARIA is a member of a family of polypeptide growth and differentiation factors that also includes glial growth factor (GGF), neu differentiation factor, and heregulin. ARIA mRNA is expressed in all cholinergic neurons of the central nervous systems of rats and chicks, including spinal cord motor neurons. In vitro, ARIA elevates the rate of acetylcholine receptor incorporation into the plasma membrane of primary cultures of chick myotubes. To study whether ARIA may regulate the synthesis of junctional synaptic acetylcholine receptors in chick embryos, we have developed riboprobes and polyclonal antibody reagents that recognize isoforms of ARIA that include an amino-terminal immunoglobulin C2 domain and examined the expression and distribution of ARIA in motor neurons and at the neuromuscular junction. We detected significant ARIA mRNA expression in motor neurons as early as embryonic day 5, around the time that motor axons are making initial synaptic contacts with their target muscle cells. In older embryos and postnatal animals, we found ARIA protein concentrated in the synaptic cleft at neuromuscular junctions, consistent with transport down motor axons and release at nerve terminals. At high resolution using immunoelectron microscopy, we detected ARIA immunoreactivity exclusively in the synaptic basal lamina in a pattern consistent with binding to synapse specific components on the presynaptic side of the basal lamina. These results support a role for ARIA as a trophic factor released by motor neuron terminals that may regulate the formation of mature neuromuscular synapses.

scholarly journals Murine muscle stem cell response to perturbations of the neuromuscular junction are attenuated with aging

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jacqueline Larouche ◽  
Mahir Mohiuddin ◽  
Jeongmoon J Choi ◽  
Peter J Ulintz ◽  
Paula M Fraczek ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Neuromuscular Diseases ◽  
Lineage Tracing ◽  
Genetic Rescue ◽  
Muscle Stem Cells ◽  
Transgenic Murine Model ◽  
And Function ◽  
The Relationship

During aging and neuromuscular diseases, there is a progressive loss of skeletal muscle volume and function impacting mobility and quality of life. Muscle loss is often associated with denervation and a loss of resident muscle stem cells (satellite cells or MuSCs), however, the relationship between MuSCs and innervation has not been established. Herein, we administered severe neuromuscular trauma to a transgenic murine model that permits MuSC lineage tracing. We show that a subset of MuSCs specifically engraft in a position proximal to the neuromuscular junction (NMJ), the synapse between myofibers and motor neurons, in healthy young adult muscles. In aging and in a mouse model of neuromuscular degeneration (Cu/Zn superoxide dismutase knockout – Sod1-/-), this localized engraftment behavior was reduced. Genetic rescue of motor neurons in Sod1-/- mice reestablished integrity of the NMJ in a manner akin to young muscle and partially restored MuSC ability to engraft into positions proximal to the NMJ. Using single cell RNA-sequencing of MuSCs isolated from aged muscle, we demonstrate that a subset of MuSCs are molecularly distinguishable from MuSCs responding to myofiber injury and share similarity to synaptic myonuclei. Collectively, these data reveal unique features of MuSCs that respond to synaptic perturbations caused by aging and other stressors.

scholarly journals A presynaptic spectrin network controls active zone assembly and neurotransmitter release

2019 ◽  
Author(s):  
Qi Wang ◽  
Lindsey Friend ◽  
Rosario Vicidomini ◽  
Tae Hee Han ◽  
Peter Nguyen ◽  
...  
Keyword(s):  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Cleft ◽  
Structure And Function ◽  
Dynamic Changes ◽  
Synaptic Structure ◽  
Synaptic Boutons ◽  
Active Zones ◽  
And Function ◽  
Spectrin Network

ABSTRACTWe have previously reported that Drosophila Tenectin (Tnc) recruits αPS2/βPS integrin to ensure structural and functional integrity at larval NMJs (Wang et al., 2018). In muscles, Tnc/integrin engages the spectrin network to regulate the size and architecture of synaptic boutons. In neurons, Tnc/integrin controls neurotransmitter release. Here we show that presynaptic Tnc/integrin modulates the synaptic accumulation of key active zone components, including the Ca2+ channel Cac and the active zone scaffold Brp. Presynaptic α-Spectrin appears to be both required and sufficient for the recruitment of Cac and Brp. We visualized the endogenous α-Spectrin and found that Tnc controls spectrin recruitment at synaptic terminals. Thus, Tnc/integrin anchors the presynaptic spectrin network and ensures the proper assembly and function of the active zones. Since pre- and postsynaptic Tnc/integrin limit each other, we hypothesize that this pathway links dynamic changes within the synaptic cleft to changes in synaptic structure and function.

Mechanisms Regulating Neuromuscular Junction Development and Function and Causes of Muscle Wasting

2015 ◽  
Vol 95 (3) ◽  
pp. 809-852 ◽  
Author(s):  
Lionel A. Tintignac ◽  
Hans-Rudolf Brenner ◽  
Markus A. Rüegg
Keyword(s):  
Neuromuscular Junction ◽  
Muscle Mass ◽  
Motor Neurons ◽  
Structural Changes ◽  
Muscle Wasting ◽  
Chemical Synapse ◽  
Neuromuscular Activity ◽  
Medical Need ◽  
Metabolic Properties ◽  
And Function

The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.

scholarly journals Early detachment of neuromuscular junction proteins in ALS mice with SODG93A mutation

2009 ◽  
Vol 1 (1) ◽  
pp. 16 ◽  
Author(s):  
Hisashi Narai ◽  
Yasuhiro Manabe ◽  
Makiko Nagai ◽  
Isao Nagano ◽  
Yasuyuki Ohta ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Transgenic Animals ◽  
Synaptic Cleft ◽  
Nerve Terminals ◽  
Double Positive ◽  
Copper Zinc Superoxide Dismutase ◽  
Sod1g93a Mice ◽  
The Status

The transgenic animals with mutant copper/zinc superoxide dismutase (SOD1) DNA develop paralytic motor neuron disease resembling human amyotrophic lateral sclerosis (ALS) patients and are commonly used as models for ALS. In the transgenic (Tg) mice with the G93A mutation of the human SOD1 gene (SOD1G93A mice), the loss of ventral root axons and the synapses between the muscles and the motor neurons suggested that the motor neuron degeneration might proceed in a dying-back degeneration pattern. To reveal the relationship between axonal degeneration and the progression of the muscle atrophy in the SOD1G93A mice, we investigated the status of the neuromuscular junction along the disease progression. As a presynaptic or postsynaptic marker of neuromuscular junction (NMJ), anti-synaptic vesicle protein 2 (anti-SV2) antibody and a-bungarotoxin (a-BuTX ) were chosen in this study and, as a marker of synaptic cleft, anti-agrin antibody was chosen in this study. In the immunohistochemistry of a-BuTX and anti-SV2 antibody, the percentages of double positive NMJs among a-BuTX single positive were decreased in Tg mice through time from ten weeks. The number of postsynaptic acethylcholine receptor (AChR) clusters did not decrease in Tg mice even at the end stage. Immunohistochemistry of a-BuTX and anti-agrin antibody revealed that the increase of immunopositive area of anti-agrin antibody around the muscle fiber in Tg mice from ten weeks of age. In this study, we revealed that the detachment of nerve terminals started at ten weeks in Tg mice. The levels of AChR did not change throughout 5-20 weeks of age in both groups of mice, and AChR remains clustering at NMJs, suggesting that the muscle abnormality is the result of detachment of nerve terminals.

scholarly journals The Vesicular Acetylcholine Transporter Is Required for Neuromuscular Development and Function

2009 ◽  
Vol 29 (19) ◽  
pp. 5238-5250 ◽  
Author(s):  
Braulio M. de Castro ◽  
Xavier De Jaeger ◽  
Cristina Martins-Silva ◽  
Ricardo D. F. Lima ◽  
Ernani Amaral ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Choline Acetyltransferase ◽  
Knockout Mice ◽  
Synaptic Vesicles ◽  
Electrophysiological Recordings ◽  
Physiological Relevance ◽  
And Function ◽  
Neuromuscular Development ◽  
High Affinity Choline Transporter

ABSTRACT The vesicular acetylcholine (ACh) transporter (VAChT) mediates ACh storage by synaptic vesicles. However, the VAChT-independent release of ACh is believed to be important during development. Here we generated VAChT knockout mice and tested the physiological relevance of the VAChT-independent release of ACh. Homozygous VAChT knockout mice died shortly after birth, indicating that VAChT-mediated storage of ACh is essential for life. Indeed, synaptosomes obtained from brains of homozygous knockouts were incapable of releasing ACh in response to depolarization. Surprisingly, electrophysiological recordings at the skeletal-neuromuscular junction show that VAChT knockout mice present spontaneous miniature end-plate potentials with reduced amplitude and frequency, which are likely the result of a passive transport of ACh into synaptic vesicles. Interestingly, VAChT knockouts exhibit substantial increases in amounts of choline acetyltransferase, high-affinity choline transporter, and ACh. However, the development of the neuromuscular junction in these mice is severely affected. Mutant VAChT mice show increases in motoneuron and nerve terminal numbers. End plates are large, nerves exhibit abnormal sprouting, and muscle is necrotic. The abnormalities are similar to those of mice that cannot synthesize ACh due to a lack of choline acetyltransferase. Our results indicate that VAChT is essential to the normal development of motor neurons and the release of ACh.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

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