scholarly journals Single Cell Deconstruction of Muscle Stem Cell Heterogeneity During Aging Reveals Sensitivity to the Neuromuscular Junction

2020 ◽  
Author(s):  
Peter J. Ulintz ◽  
Jacqueline Larouche ◽  
Mahir Mohiuddin ◽  
Jesus Castor Macias ◽  
Sarah J. Kurpiers ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Single Cell ◽  
Motor Neurons ◽  
Satellite Cells ◽  
Neural Control ◽  
Neuromuscular Diseases ◽  
Neuromuscular Synapse ◽  
List Type ◽  
Genetic Rescue ◽  
Before And After

AbstractDuring aging and neuromuscular diseases, there is a progressive loss of skeletal muscle volume and function in that impacts mobility and quality of life. Muscle loss is often associated with denervation and a loss of resident muscle stem cells (satellite cells or MuSCs), but the relationship between MuSCs and neural control has not been established. Herein, using a combination of single-cell transcriptomic analysis, high-resolution immunofluorescence imaging and transgenic young and aged mice as well as from mice with neuromuscular degeneration (Sod1-/-), a compensatory neuro-responsive function for a subset of MuSCs was identified. Genetic rescue of motor neurons in Sod1-/- mice reduced this subset of MuSCs and restored integrity of the neuromuscular junction (NMJ) in a manner akin to young muscle. Administration of severe neuromuscular trauma induced young MuSCs to specifically engraft in a position proximal to the NMJ but in aging, this behavior was abolished. Contrasting the expression programs of young and aged MuSCs after muscle injury at the single cell level, we observed distinctive gene expression programs between responses to neuro-muscular degeneration and muscle trauma. Collectively, these data reveal MuSCs sense synaptic perturbations during aging and neuro-muscular deterioration, and can exert support for the NMJ, particularly in young muscle.HighlightsTranscriptional landscapes of single satellite cells from different ages before and after injury as well as neurodegenerative models before and after nervous rescueA population of satellite cells reside in close proximity to neuromuscular synapse, which are lost with ageDenervation promotes satellite cell engraftment into post-synaptic regions of young as opposed to aged muscle

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 Comparison of neuromuscular junction dynamics following ischemic and aged skeletal muscle

2021 ◽  
Author(s):  
Berna Aliya ◽  
Mahir Mohiuddin ◽  
Jeongmoon Choi ◽  
Gunjae Jeong ◽  
Innie Kang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Acetylcholine Receptors ◽  
Neuromuscular Diseases ◽  
Neuromuscular Synapse ◽  
Imaging Method ◽  
Aging Condition ◽  
Neuromuscular Synapses ◽  
Neuronal Degradation

Both aging and neuromuscular diseases lead to significant changes in the morphology and functionality of the neuromuscular synapse. Skeletal muscles display a remarkable regenerative capacity, however, are still susceptible to diseases of aging and peripheral nerve perturbations. In this study, we assessed how neuromuscular synapses differ in aged and injured skeletal muscle using an improved neuromuscular junction (NMJ) staining and imaging method. We found that both aged and ischemic skeletal muscle display Wallerian degeneration of the presynaptic motor axons and fragmentation of postsynaptic acetylcholine receptors (AChRs). Quantifiable measurements of various metrics of the NMJs provide a more concrete idea of the dynamics that are occurring in the muscle microenvironment. We questioned whether neuronal degradation precedes myofiber atrophy or vice versa. Previously, it was shown that a cellular crosstalk exists among the motor neurons, myofibers, vasculature, and mitochondria within the muscle microdomain. It is apparent that lack of blood flow to motor neurons in ischemic skeletal muscle disrupts the structure of NMJs, however it is unclear if the aging condition experiences similar dynamics. We demonstrated that both aged and ischemic skeletal muscle demonstrate similar patterns of degeneration, characterized by a smaller percentage overlap of presynaptic and postsynaptic sides, greater fragmentation of AChRs, and a smaller area of AChR clusters. Together, these results reveal high resolution, precise parallels between the aged and ischemic NMJs.

scholarly journals The p75NTR neurotrophin receptor is required to organize the mature neuromuscular synapse by regulating synaptic vesicle availability

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Viviana Pérez ◽  
Francisca Bermedo-Garcia ◽  
Diego Zelada ◽  
Felipe A. Court ◽  
Miguel Ángel Pérez ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Neuronal Damage ◽  
Neuromuscular Synapse ◽  
Force Production ◽  
Synaptic Function ◽  
Neurotrophin Receptor ◽  
Acetylcholinesterase Inhibition ◽  
Pharmacological Intervention

Abstract The coordinated movement of organisms relies on efficient nerve-muscle communication at the neuromuscular junction. After peripheral nerve injury or neurodegeneration, motor neurons and Schwann cells increase the expression of the p75NTR pan-neurotrophin receptor. Even though p75NTR targeting has emerged as a promising therapeutic strategy to delay peripheral neuronal damage progression, the effects of long-term p75NTR inhibition at the mature neuromuscular junction have not been elucidated. We performed quantitative neuroanathomical analyses of the neuromuscular junction in p75NTR null mice by laser confocal and electron microscopy, which were complemented with electromyography, locomotor tests, and pharmacological intervention studies. Mature neuromuscular synapses of p75NTR null mice show impaired postsynaptic organization and ultrastructural complexity, which correlate with altered synaptic function at the levels of nerve activity-induced muscle responses, muscle fiber structure, force production, and locomotor performance. Our results on primary myotubes and denervated muscles indicate that muscle-derived p75NTR does not play a major role on postsynaptic organization. In turn, motor axon terminals of p75NTR null mice display a strong reduction in the number of synaptic vesicles and active zones. According to the observed pre and postsynaptic defects, pharmacological acetylcholinesterase inhibition rescued nerve-dependent muscle response and force production in p75NTR null mice. Our findings revealing that p75NTR is required to organize mature neuromuscular junctions contribute to a comprehensive view of the possible effects caused by therapeutic attempts to target p75NTR.

scholarly journals Aberrant Morphology and Residual Transmitter Release at the Munc13-Deficient Mouse Neuromuscular Synapse

2005 ◽  
Vol 25 (14) ◽  
pp. 5973-5984 ◽  
Author(s):  
Frédérique Varoqueaux ◽  
Michèle S. Sons ◽  
Jaap J. Plomp ◽  
Nils Brose
Keyword(s):  
Neuromuscular Junction ◽  
Synaptic Vesicle ◽  
Motor Neurons ◽  
Transmitter Release ◽  
Hippocampal Neurons ◽  
Neuromuscular Junctions ◽  
Neuromuscular Synapse ◽  
Synaptic Activity ◽  
Neuromuscular Synaptogenesis ◽  
Deficient Mice

ABSTRACT In cultured hippocampal neurons, synaptogenesis is largely independent of synaptic transmission, while several accounts in the literature indicate that synaptogenesis at cholinergic neuromuscular junctions in mammals appears to partially depend on synaptic activity. To systematically examine the role of synaptic activity in synaptogenesis at the neuromuscular junction, we investigated neuromuscular synaptogenesis and neurotransmitter release of mice lacking all synaptic vesicle priming proteins of the Munc13 family. Munc13-deficient mice are completely paralyzed at birth and die immediately, but form specialized neuromuscular endplates that display typical synaptic features. However, the distribution, number, size, and shape of these synapses, as well as the number of motor neurons they originate from and the maturation state of muscle cells, are profoundly altered. Surprisingly, Munc13-deficient synapses exhibit significantly increased spontaneous quantal acetylcholine release, although fewer fusion-competent synaptic vesicles are present and nerve stimulation-evoked secretion is hardly elicitable and strongly reduced in magnitude. We conclude that the residual transmitter release in Munc13-deficient mice is not sufficient to sustain normal synaptogenesis at the neuromuscular junction, essentially causing morphological aberrations that are also seen upon total blockade of neuromuscular transmission in other genetic models. Our data confirm the importance of Munc13 proteins in synaptic vesicle priming at the neuromuscular junction but indicate also that priming at this synapse may differ from priming at glutamatergic and γ-aminobutyric acid-ergic synapses and is partly Munc13 independent. Thus, non-Munc13 priming proteins exist at this synapse or vesicle priming occurs in part spontaneously: i.e., without dedicated priming proteins in the release machinery.

scholarly journals Temporal single-cell transcriptomes of zebrafish spinal cord pMN progenitors reveal distinct neuronal and glial progenitor populations

2021 ◽  
Author(s):  
Kayt Scott ◽  
Rebecca O’Rourke ◽  
Caitlin C. Winkler ◽  
Christina A. Kearns ◽  
Bruce Appel
Keyword(s):  
Spinal Cord ◽  
Transcription Factor ◽  
Single Cell ◽  
Progenitor Cells ◽  
Rna Sequencing ◽  
Motor Neurons ◽  
Marker Genes ◽  
List Type ◽  
Fate Mapping ◽  
Single Cell Rna Sequencing

AbstractVentral spinal cord progenitor cells, which express the basic helix loop helix transcription factor Olig2, sequentially produce motor neurons and oligodendrocyte precursor cells (OPCs). Following specification some OPCs differentiate as myelinating oligodendrocytes while others persist as OPCs. Though a considerable amount of work has described the molecular profiles that define motor neurons, OPCs, and oligodendrocytes, less is known about the progenitors that produce them. To identify the developmental origins and transcriptional profiles of motor neurons and OPCs, we performed single-cell RNA sequencing on isolated pMN cells from embryonic zebrafish trunk tissue at stages that encompassed motor neurogenesis, OPC specification, and initiation of oligodendrocyte differentiation. Downstream analyses revealed two distinct pMN progenitor populations: one that appears to produce neurons and one that appears to produce OPCs. This latter population, called Pre-OPCs, is marked by expression of GS Homeobox 2 (gsx2), a gene that encodes a homeobox transcription factor. Using fluorescent in situ hybridizations, we identified gsx2-expressing Pre-OPCs in the spinal cord prior to expression of canonical OPC marker genes. Our data therefore reveal heterogeneous gene expression profiles among pMN progenitors, supporting prior fate mapping evidence.HighlightsSingle-cell RNA sequencing reveals the developmental trajectories of neurons and glia that arise from spinal cord pMN progenitor cells in zebrafish embryosTranscriptionally distinct subpopulations of pMN progenitors are the apparent sources of neurons or oligodendrocytes, consistent with fate mapping datagsx2 expression marks pMN progenitors that produce oligodendrocyte lineage cells

scholarly journals Postsynaptic CaV1.1-driven calcium signaling coordinates presynaptic differentiation at the developing neuromuscular junction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mehmet Mahsum Kaplan ◽  
Bernhard E. Flucher
Keyword(s):  
Neuromuscular Junction ◽  
Calcium Signaling ◽  
Motor Neurons ◽  
Motor Nerve ◽  
Neuromuscular Synapse ◽  
Presynaptic Differentiation ◽  
Motor Nerves ◽  
Muscle Calcium ◽  
Activity Dependent ◽  
Postsynaptic Target

AbstractProper formation of neuromuscular synapses requires the reciprocal communication between motor neurons and muscle cells. Several anterograde and retrograde signals involved in neuromuscular junction formation are known. However the postsynaptic mechanisms regulating presynaptic differentiation are still incompletely understood. Here we report that the skeletal muscle calcium channel (CaV1.1) is required for motor nerve differentiation and that the mechanism by which CaV1.1 controls presynaptic differentiation utilizes activity-dependent calcium signaling in muscle. In mice lacking CaV1.1 or CaV1.1-driven calcium signaling motor nerves are ectopically located and aberrantly defasciculated. Axons fail to recognize their postsynaptic target structures and synaptic vesicles and active zones fail to correctly accumulate at the nerve terminals opposite AChR clusters. These presynaptic defects are independent of aberrant AChR patterning and more sensitive to deficient calcium signals. Thus, our results identify CaV1.1-driven calcium signaling in muscle as a major regulator coordinating multiple aspects of presynaptic differentiation at the neuromuscular synapse.

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

scholarly journals Single-cell transcriptomic analysis of the adult mouse spinal cord reveals molecular diversity of autonomic and skeletal motor neurons

2021 ◽  
Vol 24 (4) ◽  
pp. 572-583 ◽  
Author(s):  
Jacob A. Blum ◽  
Sandy Klemm ◽  
Jennifer L. Shadrach ◽  
Kevin A. Guttenplan ◽  
Lisa Nakayama ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Single Cell ◽  
Motor Neurons ◽  
Molecular Diversity ◽  
Adult Mouse ◽  
Transcriptomic Analysis ◽  
Mouse Spinal Cord

scholarly journals Cooperation & Liaison between Universities & Editors (CLUE): recommendations on best practice

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Elizabeth Wager ◽  
◽  
Sabine Kleinert
Keyword(s):  
Peer Review ◽  
Best Practice ◽  
Research Integrity ◽  
Decision Makers ◽  
Publication Ethics ◽  
List Type ◽  
Research Institutions ◽  
Academic Journals ◽  
Before And After ◽  
Published Research

Abstract Background Inaccurate, false or incomplete research publications may mislead readers including researchers and decision-makers. It is therefore important that such problems are identified and rectified promptly. This usually involves collaboration between the research institutions and academic journals involved, but these interactions can be problematic. Methods These recommendations were developed following discussions at World Conferences on Research Integrity in 2013 and 2017, and at a specially convened 3-day workshop in 2016 involving participants from 7 countries with expertise in publication ethics and research integrity. The recommendations aim to address issues surrounding cooperation and liaison between institutions (e.g. universities) and journals about possible and actual problems with the integrity of reported research arising before and after publication. Results The main recommendations are that research institutions should: develop mechanisms for assessing the integrity of reported research (if concerns are raised) that are distinct from processes to determine whether individual researchers have committed misconduct; release relevant sections of reports of research integrity or misconduct investigations to all journals that have published research that was investigated; take responsibility for research performed under their auspices regardless of whether the researcher still works at that institution or how long ago the work was done; work with funders to ensure essential research data is retained for at least 10 years. Journals should: respond to institutions about research integrity cases in a timely manner; have criteria for determining whether, and what type of, information and evidence relating to the integrity of research reports should be passed on to institutions; pass on research integrity concerns to institutions, regardless of whether they intend to accept the work for publication; retain peer review records for at least 10 years to enable the investigation of peer review manipulation or other inappropriate behaviour by authors or reviewers. Conclusions Various difficulties can prevent effective cooperation between academic journals and research institutions about research integrity concerns and hinder the correction of the research record if problems are discovered. While the issues and their solutions may vary across different settings, we encourage research institutions, journals and funders to consider how they might improve future collaboration and cooperation on research integrity cases.

scholarly journals Single-cell transcriptomics analysis showing functional heterogeneity in decidual stromal cells during labor

2020 ◽  
pp. jim-2020-001616
Author(s):  
Jingrui Huang ◽  
Yingming Xie ◽  
Qiaozhen Peng ◽  
Weinan Wang ◽  
Chenlin Pei ◽  
...  
Keyword(s):  
Single Cell ◽  
Stromal Cells ◽  
Atp Synthesis ◽  
Sequencing Analysis ◽  
Activator Protein 1 ◽  
Oxygen Homeostasis ◽  
Substrate Adhesion ◽  
Before And After ◽  
Cell Substrate Adhesion ◽  
Labor Onset

To investigate the heterogeneity of decidual stromal cells (DSCs) and their functional alterations during delivery, we conducted single-cell RNA sequencing analysis to characterize the transcriptomic profiles of DSCs before and after labor onset. According to their transcriptomic profiles, DSCs (6382 cells) were clustered into five subgroups with different functions. Similar to stromal cells, cells in cluster 1 were involved in cell substrate adhesion. On the other hand, cells in clusters 2 and 3 were enriched in signal transduction-related genes. Labor onset led to significant alterations in many pathways, including the activator protein 1 pathway (all clusters), as well as in the response to lipopolysaccharide (clusters 1–3). The downregulated genes were involved in coagulation, ATP synthesis, and oxygen homeostasis, possibly reflecting the oxygen and energy balance during delivery. Our findings highlight that peripartum DSCs are heterogeneous and play multiple roles in labor.

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