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Bilgin Topçuoğlu Ö, Çetintaş Afşar G, Alibaş H, Uluç K. Impact of obstructive sleep apnea on neuromuscular transmission- a descriptive study. Cranio 2024; 42:292-297. [PMID: 34228607 DOI: 10.1080/08869634.2021.1952016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Objective: Obstructive sleep apnea (OSA) is a sleep disorder accompanied by intermittent hypoxia. Neuromuscular transmission (NT) is known to be disturbed under chronic hypoxia. In this descriptive study, it has been aimed to test NT under intermittent hypoxia in OSA. Methods: Thirty-nine newly diagnosed OSA patients without any comorbidities or conditions that alter NT were included in the study. Jitter analysis was performed using a concentric needle electrode. Results: The mean jitter value of 39 OSA patients was 25.9 ± 3.7 μs. When compared to the mean reference jitter values, patients in the present study had significantly higher jitter (p < 0.001). Seven (17.9%) patients met the electrophysiological criteria for NT failure. Conclusion: The authors propose that intermittent hypoxia can be the trigger for NT failure in OSA. The interaction between increased oxidative stress and disturbed mitochondrial functions may also contribute.
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Affiliation(s)
| | - Gülgün Çetintaş Afşar
- Department of Chest Diseases, Sureyyapasa Chest Diseases and Thorax Surgery Training and Research Hospital, Istanbul, Turkey
| | - Hande Alibaş
- Department of Neurology, Marmara University, Medical School, Istanbul, Turkey
| | - Kayıhan Uluç
- Department of Neurology, Marmara University, Medical School, Istanbul, Turkey
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2
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Li A, Yi J, Li X, Dong L, Ostrow LW, Ma J, Zhou J. Distinct transcriptomic profile of satellite cells contributes to preservation of neuromuscular junctions in extraocular muscles of ALS mice. eLife 2024; 12:RP92644. [PMID: 38661532 PMCID: PMC11045223 DOI: 10.7554/elife.92644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disorder characterized by progressive weakness of almost all skeletal muscles, whereas extraocular muscles (EOMs) are comparatively spared. While hindlimb and diaphragm muscles of end-stage SOD1G93A (G93A) mice (a familial ALS mouse model) exhibit severe denervation and depletion of Pax7+satellite cells (SCs), we found that the pool of SCs and the integrity of neuromuscular junctions (NMJs) are maintained in EOMs. In cell sorting profiles, SCs derived from hindlimb and diaphragm muscles of G93A mice exhibit denervation-related activation, whereas SCs from EOMs of G93A mice display spontaneous (non-denervation-related) activation, similar to SCs from wild-type mice. Specifically, cultured EOM SCs contain more abundant transcripts of axon guidance molecules, including Cxcl12, along with more sustainable renewability than the diaphragm and hindlimb counterparts under differentiation pressure. In neuromuscular co-culture assays, AAV-delivery of Cxcl12 to G93A-hindlimb SC-derived myotubes enhances motor neuron axon extension and innervation, recapitulating the innervation capacity of EOM SC-derived myotubes. G93A mice fed with sodium butyrate (NaBu) supplementation exhibited less NMJ loss in hindlimb and diaphragm muscles. Additionally, SCs derived from G93A hindlimb and diaphragm muscles displayed elevated expression of Cxcl12 and improved renewability following NaBu treatment in vitro. Thus, the NaBu-induced transcriptomic changes resembling the patterns of EOM SCs may contribute to the beneficial effects observed in G93A mice. More broadly, the distinct transcriptomic profile of EOM SCs may offer novel therapeutic targets to slow progressive neuromuscular functional decay in ALS and provide possible 'response biomarkers' in pre-clinical and clinical studies.
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Affiliation(s)
- Ang Li
- Department of Kinesiology, College of Nursing and Health Innovation, The University of Texas at ArlingtonArlingtonUnited States
| | - Jianxun Yi
- Department of Kinesiology, College of Nursing and Health Innovation, The University of Texas at ArlingtonArlingtonUnited States
| | - Xuejun Li
- Department of Kinesiology, College of Nursing and Health Innovation, The University of Texas at ArlingtonArlingtonUnited States
| | - Li Dong
- Department of Kinesiology, College of Nursing and Health Innovation, The University of Texas at ArlingtonArlingtonUnited States
| | - Lyle W Ostrow
- Department of Neurology, Lewis Katz School of Medicine at Temple UniversityPhiladelphiaUnited States
| | - Jianjie Ma
- Department of Surgery, Division of Surgical Sciences, University of VirginiaCharlottesvilleUnited States
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, The University of Texas at ArlingtonArlingtonUnited States
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3
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Butenko O, Jensen SM, Fillié-Grijpma YE, Verpalen R, Verschuuren JJ, van der Maarel SM, Huijbers MG, Plomp JJ. Change of voltage-gated sodium channel repertoire in skeletal muscle of a MuSK myasthenia gravis mouse model. Eur J Neurosci 2024. [PMID: 38650308 DOI: 10.1111/ejn.16347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 03/11/2024] [Accepted: 03/23/2024] [Indexed: 04/25/2024]
Abstract
Muscle-specific kinase myasthenia gravis (MuSK MG) is caused by autoantibodies against MuSK in the neuromuscular junction (NMJ). MuSK MG patients have fluctuating, fatigable skeletal muscle weakness, in particular of bulbar muscles. Severity differs greatly between patients, in spite of comparable autoantibody levels. One explanation for inter-patient and inter-muscle variability in sensitivity might be variations in compensatory muscle responses. Previously, we developed a passive transfer mouse model for MuSK MG. In preliminary ex vivo experiments, we observed that muscle contraction of some mice, in particular those with milder myasthenia, had become partially insensitive to inhibition by μ-Conotoxin-GIIIB, a blocker of skeletal muscle NaV1.4 voltage-gated sodium channels. We hypothesised that changes in NaV channel expression profile, possibly co-expression of (μ-Conotoxin-GIIIB insensitive) NaV1.5 type channels, might lower the muscle fibre's firing threshold and facilitate neuromuscular synaptic transmission. To test this hypothesis, we here performed passive transfer in immuno-compromised mice, using 'high', 'intermediate' and 'low' dosing regimens of purified MuSK MG patient IgG4. We compared myasthenia levels, μ-Conotoxin-GIIIB resistance and muscle fibre action potential characteristics and firing thresholds. High- and intermediate-dosed mice showed clear, progressive myasthenia, not seen in low-dosed animals. However, diaphragm NMJ electrophysiology demonstrated almost equal myasthenic severities amongst all regimens. Nonetheless, low-dosed mouse diaphragms showed a much higher degree of μ-Conotoxin-GIIIB resistance. This was not explained by upregulation of Scn5a (the NaV1.5 gene), lowered muscle fibre firing thresholds or histologically detectable upregulated NaV1.5 channels. It remains to be established which factors are responsible for the observed μ-Conotoxin-GIIIB insensitivity and whether the NaV repertoire change is compensatory beneficial or a bystander effect.
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Affiliation(s)
- Olena Butenko
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Stine Marie Jensen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Robyn Verpalen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan J Verschuuren
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Maartje G Huijbers
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jaap J Plomp
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
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4
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Chang YC, Gao Y, Lee JY, Peng YJ, Langen J, Chang KT. Identification of secretory autophagy as a mechanism modulating activity-induced synaptic remodeling. Proc Natl Acad Sci U S A 2024; 121:e2315958121. [PMID: 38588427 PMCID: PMC11032469 DOI: 10.1073/pnas.2315958121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 02/23/2024] [Indexed: 04/10/2024] Open
Abstract
The ability of neurons to rapidly remodel their synaptic structure and strength in response to neuronal activity is highly conserved across species and crucial for complex brain functions. However, mechanisms required to elicit and coordinate the acute, activity-dependent structural changes across synapses are not well understood, as neurodevelopment and structural plasticity are tightly linked. Here, using an RNAi screen in Drosophila against genes affecting nervous system functions in humans, we uncouple cellular processes important for synaptic plasticity and synapse development. We find mutations associated with neurodegenerative and mental health disorders are 2-times more likely to affect activity-induced synaptic remodeling than synapse development. We report that while both synapse development and activity-induced synaptic remodeling at the fly NMJ require macroautophagy (hereafter referred to as autophagy), bifurcation in the autophagy pathway differentially impacts development and synaptic plasticity. We demonstrate that neuronal activity enhances autophagy activation but diminishes degradative autophagy, thereby driving the pathway towards autophagy-based secretion. Presynaptic knockdown of Snap29, Sec22, or Rab8, proteins implicated in the secretory autophagy pathway, is sufficient to abolish activity-induced synaptic remodeling. This study uncovers secretory autophagy as a transsynaptic signaling mechanism modulating synaptic plasticity.
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Affiliation(s)
- Yen-Ching Chang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Yuan Gao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Joo Yeun Lee
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Yi-Jheng Peng
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Jennifer Langen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Karen T. Chang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
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5
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von Saucken VE, Windner SE, Baylies MK. Postsynaptic BMP signaling regulates myonuclear properties in Drosophila larval muscles. bioRxiv 2024:2024.04.10.588944. [PMID: 38645063 PMCID: PMC11030338 DOI: 10.1101/2024.04.10.588944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
The syncytial mammalian muscle fiber contains a heterogeneous population of (myo)nuclei. At the neuromuscular junction (NMJ), myonuclei have specialized positioning and gene expression. However, it remains unclear how myonuclei are recruited and what regulates myonuclear output at the NMJ. Here, we identify specific properties of myonuclei located near the Drosophila larval NMJ. These synaptic myonuclei have increased size in relation to their surrounding cytoplasmic domain (scaling), increased DNA content (ploidy), and increased levels of transcription factor pMad, a readout for BMP signaling activity. Our genetic manipulations show local BMP signaling affects muscle size, nuclear size, ploidy, and NMJ size and function. In support, RNA sequencing analysis reveals that pMad regulates genes involved in muscle growth, ploidy (i.e., E2f1), and neurotransmission. Our data suggest that muscle BMP signaling instructs synaptic myonuclear output that then positively shapes the NMJ synapse. This study deepens our understanding of how myonuclear heterogeneity supports local signaling demands to fine tune cellular function and NMJ activity.
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Affiliation(s)
- Victoria E. von Saucken
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065 USA
- Weill Cornell-Rockefeller-Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065 USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) Program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065 USA
| | - Stefanie E. Windner
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065 USA
| | - Mary K. Baylies
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065 USA
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6
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Kovarik Z, Soreq H. Recent advances in cholinergic mechanisms: A preface for the ISCM2022 special issue. J Neurochem 2024; 168:334-338. [PMID: 38082541 DOI: 10.1111/jnc.16027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 11/21/2023] [Accepted: 11/21/2023] [Indexed: 04/13/2024]
Abstract
This preface introduces the Journal of Neurochemistry special issue on Cholinergic Mechanisms that highlights the progress in the molecular, structural, neurochemical, pharmacological, toxicological, and clinical studies of the cholinergic system which underline its complexity and impact on health and disease. This issue comprises of (systematic) reviews and original articles, the majority of which have been presented at the 17th International Symposium on Cholinergic Mechanisms (ISCM2022) held in Dubrovnik, Croatia in May 2022. The symposium brought together leading "Cholinergikers" to shed new light on cholinergic transmission, ranging from the molecular to the clinical and cognitive mechanisms.
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Affiliation(s)
- Zrinka Kovarik
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Hermona Soreq
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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7
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Ohkawara B, Kurokawa M, Kanai A, Imamura K, Chen G, Zhang R, Masuda A, Higashi K, Mori H, Suzuki Y, Kurokawa K, Ohno K. Transcriptome profile of subsynaptic myonuclei at the neuromuscular junction in embryogenesis. J Neurochem 2024; 168:342-354. [PMID: 37994470 DOI: 10.1111/jnc.16013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 10/26/2023] [Accepted: 11/03/2023] [Indexed: 11/24/2023]
Abstract
Skeletal muscle fiber is a large syncytium with multiple and evenly distributed nuclei. Adult subsynaptic myonuclei beneath the neuromuscular junction (NMJ) express specific genes, the products of which coordinately function in the maintenance of the pre- and post-synaptic regions. However, the gene expression profiles that promote the NMJ formation during embryogenesis remain largely unexplored. We performed single-nucleus RNA sequencing (snRNA-seq) analysis of embryonic and neonatal mouse diaphragms, and found that each myonucleus had a distinct transcriptome pattern during the NMJ formation. Among the previously reported NMJ-constituting genes, Dok7, Chrna1, and Chrnd are specifically expressed in subsynaptic myonuclei at E18.5. In the E18.5 diaphragm, ca. 10.7% of the myonuclei express genes for the NMJ formation (Dok7, Chrna1, and Chrnd) together with four representative β-catenin regulators (Amotl2, Ptprk, Fam53b, and Tcf7l2). Additionally, the temporal gene expression patterns of these seven genes are synchronized in differentiating C2C12 myoblasts. Amotl2 and Ptprk are expressed in the sarcoplasm, where β-catenin serves as a structural protein to organize the membrane-anchored NMJ structure. In contrast, Fam53b and Tcf7l2 are expressed in the myonucleus, where β-catenin serves as a transcriptional coactivator in Wnt/β-catenin signaling at the NMJ. In C2C12 myotubes, knockdown of Amotl2 or Ptprk markedly, and that of Fam53b and Tcf7l2 less efficiently, impair the clustering of acetylcholine receptors. In contrast, knockdown of Fam53b and Tcf7l2, but not of Amotl2 or Ptprk, impairs the gene expression of Slit2 encoding an axonal attractant for motor neurons, which is required for the maturation of motor nerve terminal. Thus, Amotl2 and Ptprk exert different roles at the NM compared to Fam53b and Tcf7l2. Additionally, Wnt ligands originating from the spinal motor neurons and the perichondrium/chondrocyte are likely to work remotely on the subsynaptic nuclei and the myotendinous junctional nuclei, respectively. We conclude that snRNA-seq analysis of embryonic/neonatal diaphragms reveal a novel coordinated expression profile especially in the Wnt/β-catenin signaling that regulate the formation of the embryonic NMJ.
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Affiliation(s)
- Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masaomi Kurokawa
- Department of Informatics, National Institute of Genetics, Shizuoka, Japan
| | - Akinori Kanai
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Kiyomi Imamura
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Guiying Chen
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Ruchen Zhang
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Koichi Higashi
- Department of Informatics, National Institute of Genetics, Shizuoka, Japan
| | - Hiroshi Mori
- Department of Informatics, National Institute of Genetics, Shizuoka, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Ken Kurokawa
- Department of Informatics, National Institute of Genetics, Shizuoka, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
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King PH. Skeletal muscle as a molecular and cellular biomarker of disease progression in amyotrophic lateral sclerosis: a narrative review. Neural Regen Res 2024; 19:747-753. [PMID: 37843208 PMCID: PMC10664124 DOI: 10.4103/1673-5374.382226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/27/2023] [Accepted: 07/19/2023] [Indexed: 10/17/2023] Open
Abstract
Amyotrophic lateral sclerosis is a fatal multisystemic neurodegenerative disease with motor neurons being a primary target. Although progressive weakness is a hallmark feature of amyotrophic lateral sclerosis, there is considerable heterogeneity, including clinical presentation, progression, and the underlying triggers for disease initiation. Based on longitudinal studies with families harboring amyotrophic lateral sclerosis-associated gene mutations, it has become apparent that overt disease is preceded by a prodromal phase, possibly in years, where compensatory mechanisms delay symptom onset. Since 85-90% of amyotrophic lateral sclerosis is sporadic, there is a strong need for identifying biomarkers that can detect this prodromal phase as motor neurons have limited capacity for regeneration. Current Food and Drug Administration-approved therapies work by slowing the degenerative process and are most effective early in the disease. Skeletal muscle, including the neuromuscular junction, manifests abnormalities at the earliest stages of the disease, before motor neuron loss, making it a promising source for identifying biomarkers of the prodromal phase. The accessibility of muscle through biopsy provides a lens into the distal motor system at earlier stages and in real time. The advent of "omics" technology has led to the identification of numerous dysregulated molecules in amyotrophic lateral sclerosis muscle, ranging from coding and non-coding RNAs to proteins and metabolites. This technology has opened the door for identifying biomarkers of disease activity and providing insight into disease mechanisms. A major challenge is correlating the myriad of dysregulated molecules with clinical or histological progression and understanding their relevance to presymptomatic phases of disease. There are two major goals of this review. The first is to summarize some of the biomarkers identified in human amyotrophic lateral sclerosis muscle that have a clinicopathological correlation with disease activity, evidence of a similar dysregulation in the SOD1G93A mouse during presymptomatic stages, and evidence of progressive change during disease progression. The second goal is to review the molecular pathways these biomarkers reflect and their potential role in mitigating or promoting disease progression, and as such, their potential as therapeutic targets in amyotrophic lateral sclerosis.
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Affiliation(s)
- Peter H. King
- Department of Neurology and Center for Neurodegeneration and Experimental Therapeutics, The University of Alabama at Birmingham, Birmingham, AL, USA; Birmingham Veterans Affairs Medical Center, Birmingham, AL, USA
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Schellino R, Boido M, Vrijbloed JW, Fariello RG, Vercelli A. Synergistically Acting on Myostatin and Agrin Pathways Increases Neuromuscular Junction Stability and Endurance in Old Mice. Aging Dis 2024; 15:893-910. [PMID: 37548943 PMCID: PMC10917542 DOI: 10.14336/ad.2023.0713-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 07/13/2023] [Indexed: 08/08/2023] Open
Abstract
Sarcopenia is the primary cause of impaired motor performance in the elderly. The current prevailing approach to counteract such condition is increasing the muscle mass through inhibition of the myostatin system: however, this strategy only moderately improves muscular strength, not being able to sustain the innervation of the hypertrophic muscle per se, leading to a progressive worsening of motor performances. Thus, we proposed the administration of ActR-Fc-nLG3, a protein that combines the soluble activin receptor, a strong myostatin inhibitor, with the C-terminal agrin nLG3 domain. This compound has the potential of reinforcing neuro-muscular stability to the hypertrophic muscle. We previously demonstrated an enhancement of motor endurance and ACh receptor aggregation in young mice after ActR-Fc-nLG3 administration. Now we extended these observations by demonstrating that also in aged (2 years-old) mice, long-term administration of ActR-Fc-nLG3 increases in a sustained way both motor endurance and muscle strength, compared with ActR-Fc, a myostatin inhibitor, alone. Histological data demonstrate that the administration of this biological improves neuromuscular stability and fiber innervation maintenance, preventing muscle fiber atrophy and inducing only moderate hypertrophy. Moreover, at the postsynaptic site we observe an increased folding in the soleplate, a likely anatomical substrate for improved neurotransmission efficiency in the NMJ, that may lead to enhanced motor endurance. We suggest that ActR-Fc-nLG3 may become a valid option for treating sarcopenia and possibly other disorders of striatal muscles.
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Affiliation(s)
- Roberta Schellino
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin 10126, Italy
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Orbassano, 10043 Italy
| | - Marina Boido
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin 10126, Italy
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Orbassano, 10043 Italy
| | | | | | - Alessandro Vercelli
- Department of Neuroscience Rita Levi-Montalcini, University of Turin, Turin 10126, Italy
- Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Orbassano, 10043 Italy
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10
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De Cicco T, Pęziński M, Wójcicka O, Pradhan BS, Jabłońska M, Rottner K, Prószyński TJ. Cortactin interacts with αDystrobrevin-1 and regulates murine neuromuscular junction morphology. Eur J Cell Biol 2024; 103:151409. [PMID: 38579603 DOI: 10.1016/j.ejcb.2024.151409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 03/24/2024] [Accepted: 03/29/2024] [Indexed: 04/07/2024] Open
Abstract
Neuromuscular junctions transmit signals from the nervous system to skeletal muscles, triggering their contraction, and their proper organization is essential for breathing and voluntary movements. αDystrobrevin-1 is a cytoplasmic component of the dystrophin-glycoprotein complex and has pivotal functions in regulating the integrity of muscle fibers and neuromuscular junctions. Previous studies identified that αDystrobrevin-1 functions in the organization of the neuromuscular junction and that its phosphorylation in the C-terminus is required in this process. Our proteomic screen identified several putative αDystrobrevin-1 interactors recruited to the Y730 site in phosphorylated and unphosphorylated states. Amongst various actin-modulating proteins, we identified the Arp2/3 complex regulator cortactin. We showed that similarly to αDystrobrevin-1, cortactin is strongly enriched at the neuromuscular postsynaptic machinery and obtained results suggesting that these two proteins interact in cell homogenates and at the neuromuscular junctions. Analysis of synaptic morphology in cortactin knockout mice showed abnormalities in the slow-twitching soleus muscle and not in the fast-twitching tibialis anterior. However, muscle strength examination did not reveal apparent deficits in knockout animals.
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Affiliation(s)
- Teresa De Cicco
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Marcin Pęziński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Olga Wójcicka
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Bhola Shankar Pradhan
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Margareta Jabłońska
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig 38124, Germany
| | - Tomasz J Prószyński
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland.
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11
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Nguyen TH, Vicidomini R, Choudhury SD, Han TH, Maric D, Brody T, Serpe M. scRNA-seq data from the larval Drosophila ventral cord provides a resource for studying motor systems function and development. Dev Cell 2024:S1534-5807(24)00186-2. [PMID: 38569548 DOI: 10.1016/j.devcel.2024.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/05/2023] [Accepted: 03/06/2024] [Indexed: 04/05/2024]
Abstract
The Drosophila larval ventral nerve cord (VNC) shares many similarities with the spinal cord of vertebrates and has emerged as a major model for understanding the development and function of motor systems. Here, we use high-quality scRNA-seq, validated by anatomical identification, to create a comprehensive census of larval VNC cell types. We show that the neural lineages that comprise the adult VNC are already defined, but quiescent, at the larval stage. Using fluorescence-activated cell sorting (FACS)-enriched populations, we separate all motor neuron bundles and link individual neuron clusters to morphologically characterized known subtypes. We discovered a glutamate receptor subunit required for basal neurotransmission and homeostasis at the larval neuromuscular junction. We describe larval glia and endorse the general view that glia perform consistent activities throughout development. This census represents an extensive resource and a powerful platform for future discoveries of cellular and molecular mechanisms in repair, regeneration, plasticity, homeostasis, and behavioral coordination.
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Affiliation(s)
| | | | | | | | - Dragan Maric
- Flow and Imaging Cytometry Core, NINDS, NIH, Bethesda, MD 20892, USA
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12
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Gessler L, Huraskin D, Eiber N, Hashemolhosseini S. The impact of canonical Wnt transcriptional repressors TLE3 and TLE4 on postsynaptic transcription at the neuromuscular junction. Front Mol Neurosci 2024; 17:1360368. [PMID: 38600964 PMCID: PMC11004254 DOI: 10.3389/fnmol.2024.1360368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/14/2024] [Indexed: 04/12/2024] Open
Abstract
Here, we investigated the role of the canonical Wnt signaling pathway transcriptional regulators at the neuromuscular junction. Upon applying a denervation paradigm, the transcription levels of Ctnnb1, Tcf7l1, Tle1, Tle2, Tle3, and Tle4 were significantly downregulated. A significant decrease in canonical Wnt signaling activity was observed using the denervation paradigm in Axin2-lacZ reporter mice. Alterations in the transcriptional profile of the myogenic lineage in response to agrin (AGRN) suggested that TLE3 and TLE4, family members of groucho transducin-like enhancer of split 3 (TLE3), transcriptional repressors known to antagonize T cell factor/lymphoid enhancer factor (TCF)-mediated target gene activation, could be important regulators of canonical Wnt signaling activity at the postsynapse. Knockouts of these genes using CRISPR/Cas9 gene editing in primary skeletal muscle stem cells, called satellite cells, led to decreased AGRN-dependent acetylcholine receptor (CHRN) clustering and reduced synaptic gene transcription upon differentiation of these cells. Overall, our findings demonstrate that TLE3 and TLE4 participate in diminishing canonical Wnt signaling activity, supporting transcription of synaptic genes and CHRN clustering at the neuromuscular junction.
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Affiliation(s)
- Lea Gessler
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Danyil Huraskin
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Nane Eiber
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Said Hashemolhosseini
- Institute of Biochemistry, Medical Faculty, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
- Muscle Research Center, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
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13
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Bao Z, Cui C, Liu C, Long Y, Wong RMY, Chai S, Qin L, Rubin C, Yip BHK, Xu Z, Jiang Q, Chow SKH, Cheung WH. Prevention of age-related neuromuscular junction degeneration in sarcopenia by low-magnitude high-frequency vibration. Aging Cell 2024:e14156. [PMID: 38532712 DOI: 10.1111/acel.14156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 03/11/2024] [Accepted: 03/12/2024] [Indexed: 03/28/2024] Open
Abstract
Neuromuscular junction (NMJ) degeneration is one of pathological factors of sarcopenia. Low-magnitude high-frequency vibration (LMHFV) was reported effective in alleviating the sarcopenia progress. However, no previous study has investigated treatment effects of LMHFV targeting NMJ degeneration in sarcopenia. We first compared morphological differences of NMJ between sarcopenic and non-sarcopenic subjects, as well as young and old C57BL/6 mice. We then systematically characterized the age-related degeneration of NMJ in SAMP8 against its control strain, SAMR1 mice, from 3 to 12 months old. We also investigated effects of LMHFV in SAMP8 on the maintenance of NMJ during the onset of sarcopenia with respect to the Agrin-LRP4-MuSK-Dok7 pathway and investigated the mechanism related to ERK1/2 signaling. We observed sarcopenic/old NMJ presented increased acetylcholine receptors (AChRs) cluster fragmentation and discontinuity than non-sarcopenic/young NMJ. In SAMP8, NMJ degeneration (morphologically at 6 months and functionally at 8 months) was observed associated with the sarcopenia onset (10 months). SAMR1 showed improved NMJ morphology and function compared with SAMP8 at 10 months. Skeletal muscle performance was improved at Month 4 post-LMHFV treatment. Vibration group presented improved NMJ function at Months 2 and 6 posttreatment, accompanied with alleviated morphological degeneration at Month 4 posttreatment. LMHFV increased Dok7 expression at Month 4 posttreatment. In vitro, LMHFV could promote AChRs clustering in myotubes by increasing Dok7 expression through suppressing ERK1/2 phosphorylation. In conclusion, NMJ degeneration was observed associated with the sarcopenia onset in SAMP8. LMHFV may attenuate NMJ degeneration and sarcopenia progression by increasing Dok7 expression through suppressing ERK1/2 phosphorylation.
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Affiliation(s)
- Zhengyuan Bao
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
- Division of Sports Medicine and Adult Reconstructive Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Can Cui
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chaoran Liu
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yufeng Long
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ronald Man Yeung Wong
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Senlin Chai
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
- Division of Sports Medicine and Adult Reconstructive Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Ling Qin
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Clinton Rubin
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Benjamin Hon Kei Yip
- School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Zhihong Xu
- Division of Sports Medicine and Adult Reconstructive Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Qing Jiang
- Division of Sports Medicine and Adult Reconstructive Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Simon Kwoon-Ho Chow
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
- Department of Orthopaedic Surgery, Stanford University, Stanford, California, USA
| | - Wing-Hoi Cheung
- Musculoskleletal Research Laboratory, Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
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14
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Korb A, Tajbakhsh S, Comai GE. Functional specialisation and coordination of myonuclei. Biol Rev Camb Philos Soc 2024. [PMID: 38477382 DOI: 10.1111/brv.13063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 03/14/2024]
Abstract
Myofibres serve as the functional unit for locomotion, with the sarcomere as fundamental subunit. Running the entire length of this structure are hundreds of myonuclei, located at the periphery of the myofibre, juxtaposed to the plasma membrane. Myonuclear specialisation and clustering at the centre and ends of the fibre are known to be essential for muscle contraction, yet the molecular basis of this regionalisation has remained unclear. While the 'myonuclear domain hypothesis' helped explain how myonuclei can independently govern large cytoplasmic territories, novel technologies have provided granularity on the diverse transcriptional programs running simultaneously within the syncytia and added a new perspective on how myonuclei communicate. Building upon this, we explore the critical cellular and molecular sources of transcriptional and functional heterogeneity within myofibres, discussing the impact of intrinsic and extrinsic factors on myonuclear programs. This knowledge provides new insights for understanding muscle development, repair, and disease, but also opens avenues for the development of novel and precise therapeutic approaches.
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Affiliation(s)
- Amaury Korb
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Shahragim Tajbakhsh
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Glenda E Comai
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
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15
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Sert O, Ding X, Zhang C, Mi R, Hoke A, Rasband MN. Postsynaptic β1 spectrin maintains Na + channels at the neuromuscular junction. J Physiol 2024; 602:1127-1145. [PMID: 38441922 PMCID: PMC10942750 DOI: 10.1113/jp285894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 02/13/2024] [Indexed: 03/16/2024] Open
Abstract
Spectrins function together with actin as obligatory subunits of the submembranous cytoskeleton. Spectrins maintain cell shape, resist mechanical forces, and stabilize ion channel and transporter protein complexes through binding to scaffolding proteins. Recently, pathogenic variants of SPTBN4 (β4 spectrin) were reported to cause both neuropathy and myopathy. Although the role of β4 spectrin in neurons is mostly understood, its function in skeletal muscle, another excitable tissue subject to large forces, is unknown. Here, using a muscle specific β4 spectrin conditional knockout mouse, we show that β4 spectrin does not contribute to muscle function. In addition, we show β4 spectrin is not present in muscle, indicating the previously reported myopathy associated with pathogenic SPTBN4 variants is neurogenic in origin. More broadly, we show that α2, β1 and β2 spectrins are found in skeletal muscle, with α2 and β1 spectrins being enriched at the postsynaptic neuromuscular junction (NMJ). Surprisingly, using muscle specific conditional knockout mice, we show that loss of α2 and β2 spectrins had no effect on muscle health, function or the enrichment of β1 spectrin at the NMJ. Muscle specific deletion of β1 spectrin also had no effect on muscle health, but, with increasing age, resulted in the loss of clustered NMJ Na+ channels. Together, our results suggest that muscle β1 spectrin functions independently of an associated α spectrin to maintain Na+ channel clustering at the postsynaptic NMJ. Furthermore, despite repeated exposure to strong forces and in contrast to neurons, muscles do not require spectrin cytoskeletons to maintain cell shape or integrity. KEY POINTS: The myopathy found in pathogenic human SPTBN4 variants (where SPTBN4 is the gene encoding β4 spectrin) is neurogenic in origin. β1 spectrin plays essential roles in maintaining the density of neuromuscular junction Nav1.4 Na+ channels. By contrast to the canonical view of spectrin organization and function, we show that β1 spectrin can function independently of an associated α spectrin. Despite the large mechanical forces experienced by muscle, we show that spectrins are not required for muscle cell integrity. This is in stark contrast to red blood cells and the axons of neurons.
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Affiliation(s)
- Ozlem Sert
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Xiaoyun Ding
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Chuansheng Zhang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
| | - Ruifa Mi
- Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Ahmet Hoke
- Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205
| | - Matthew N. Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA 77030
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16
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Lindroos JLV, Bjørk MH, Gilhus NE. Transient Neonatal Myasthenia Gravis as a Common Complication of a Rare Disease: A Systematic Review. J Clin Med 2024; 13:1136. [PMID: 38398450 PMCID: PMC10889526 DOI: 10.3390/jcm13041136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/09/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024] Open
Abstract
Myasthenia gravis (MG) is a rare autoimmune disease. Transient neonatal myasthenia gravis (TNMG) is caused by pathogenic maternal autoantibodies that cross the placenta and disrupt signaling at the neuromuscular junction. This is a systematic review of this transient immunoglobulin G (IgG)-mediated disease. TNMG affects 10-20% of children born to mothers with MG. The severity of symptoms ranges from minor feeding difficulties to life-threatening respiratory weakness. Minor symptoms might go unnoticed but can still interfere with breastfeeding. Acetylcholine-esterase inhibitors and antibody-clearing therapies such as immunoglobulins can be used to treat TNMG, but most children do well with observation only. TNMG is self-limiting within weeks as circulating antibodies are naturally cleared from the blood. In rare cases, TNMG is associated with permanent skeletal malformations or permanent myopathy. The mother's antibodies can also lead to spontaneous abortions. All healthcare professionals meeting pregnant or birthing women with MG or their neonates should be aware of TNMG. TNMG is hard to predict. Reoccurrence is common among siblings. Pre-pregnancy thymectomy and intravenous immunoglobulins during pregnancy reduce the risk. Neonatal fragment crystallizable receptor (FcRn) blocking drugs for MG might reduce TNMG risk.
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Affiliation(s)
- Jenny Linnea Victoria Lindroos
- Department of Clinical Medicine, University of Bergen, 5020 Bergen, Norway; (J.L.V.L.); (M.-H.B.)
- Department of Neurology, Haukeland University Hospital, 5053 Bergen, Norway
| | - Marte-Helene Bjørk
- Department of Clinical Medicine, University of Bergen, 5020 Bergen, Norway; (J.L.V.L.); (M.-H.B.)
- Department of Neurology, Haukeland University Hospital, 5053 Bergen, Norway
| | - Nils Erik Gilhus
- Department of Clinical Medicine, University of Bergen, 5020 Bergen, Norway; (J.L.V.L.); (M.-H.B.)
- Department of Neurology, Haukeland University Hospital, 5053 Bergen, Norway
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17
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Gonzalez D, Vásquez-Doorman C, Luna A, Allende ML. Modeling Spinal Muscular Atrophy in Zebrafish: Current Advances and Future Perspectives. Int J Mol Sci 2024; 25:1962. [PMID: 38396640 PMCID: PMC10888324 DOI: 10.3390/ijms25041962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/20/2023] [Accepted: 12/29/2023] [Indexed: 02/25/2024] Open
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease characterized by degeneration of lower motor neurons (LMNs), causing muscle weakness, atrophy, and paralysis. SMA is caused by mutations in the Survival Motor Neuron 1 (SMN1) gene and can be classified into four subgroups, depending on its severity. Even though the genetic component of SMA is well known, the precise mechanisms underlying its pathophysiology remain elusive. Thus far, there are three FDA-approved drugs for treating SMA. While these treatments have shown promising results, their costs are extremely high and unaffordable for most patients. Thus, more efforts are needed in order to identify novel therapeutic targets. In this context, zebrafish (Danio rerio) stands out as an ideal animal model for investigating neurodegenerative diseases like SMA. Its well-defined motor neuron circuits and straightforward neuromuscular structure offer distinct advantages. The zebrafish's suitability arises from its low-cost genetic manipulation and optical transparency exhibited during larval stages, which facilitates in vivo microscopy. This review explores advancements in SMA research over the past two decades, beginning with the creation of the first zebrafish model. Our review focuses on the findings using different SMA zebrafish models generated to date, including potential therapeutic targets such as U snRNPs, Etv5b, PLS3, CORO1C, Pgrn, Cpg15, Uba1, Necdin, and Pgk1, among others. Lastly, we conclude our review by emphasizing the future perspectives in the field, namely exploiting zebrafish capacity for high-throughput screening. Zebrafish, with its unique attributes, proves to be an ideal model for studying motor neuron diseases and unraveling the complexity of neuromuscular defects.
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Affiliation(s)
- David Gonzalez
- Millennium Institute Center for Genome Regulation, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, RM, Chile
- Departamento de Ciencias Químicas y Biológicas, Facultad de Ciencias de la Salud, Universidad Bernardo O'Higgins, Santiago 8370854, RM, Chile
| | - Constanza Vásquez-Doorman
- Millennium Institute Center for Genome Regulation, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, RM, Chile
- Departamento de Ciencias Químicas y Biológicas, Facultad de Ciencias de la Salud, Universidad Bernardo O'Higgins, Santiago 8370854, RM, Chile
| | - Adolfo Luna
- Departamento de Ciencias Químicas y Biológicas, Facultad de Ciencias de la Salud, Universidad Bernardo O'Higgins, Santiago 8370854, RM, Chile
| | - Miguel L Allende
- Millennium Institute Center for Genome Regulation, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, RM, Chile
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18
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Hann SH, Kim SY, Kim YL, Jo YW, Kang JS, Park H, Choi SY, Kong YY. Depletion of SMN protein in mesenchymal progenitors impairs the development of bone and neuromuscular junction in spinal muscular atrophy. eLife 2024; 12:RP92731. [PMID: 38318851 PMCID: PMC10945524 DOI: 10.7554/elife.92731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by the deficiency of the survival motor neuron (SMN) protein, which leads to motor neuron dysfunction and muscle atrophy. In addition to the requirement for SMN in motor neurons, recent studies suggest that SMN deficiency in peripheral tissues plays a key role in the pathogenesis of SMA. Using limb mesenchymal progenitor cell (MPC)-specific SMN-depleted mouse models, we reveal that SMN reduction in limb MPCs causes defects in the development of bone and neuromuscular junction (NMJ). Specifically, these mice exhibited impaired growth plate homeostasis and reduced insulin-like growth factor (IGF) signaling from chondrocytes, rather than from the liver. Furthermore, the reduction of SMN in fibro-adipogenic progenitors (FAPs) resulted in abnormal NMJ maturation, altered release of neurotransmitters, and NMJ morphological defects. Transplantation of healthy FAPs rescued the morphological deterioration. Our findings highlight the significance of mesenchymal SMN in neuromusculoskeletal pathogenesis of SMA and provide insights into potential therapeutic strategies targeting mesenchymal cells for the treatment of SMA.
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Affiliation(s)
- Sang-Hyeon Hann
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seon-Yong Kim
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Ye Lynne Kim
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Young-Woo Jo
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jong-Seol Kang
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hyerim Park
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Young-Yun Kong
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
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McGorum BC, Davey T, Dosi MCM, Keen JA, Morrison LR, Pirie RS, Shaw DJ, Harris JB. Equine grass sickness is associated with major abnormalities in the ultrastructure of skeletal neuromuscular junctions. Equine Vet J 2024. [PMID: 38301732 DOI: 10.1111/evj.14063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/04/2024] [Indexed: 02/03/2024]
Abstract
BACKGROUND Equine grass sickness (EGS) is a frequently fatal multisystem neuropathy of equids. The aetiology is unknown; proposed causes include toxicoinfection with Clostridium botulinum and a mycotoxicosis. The effect of EGS on the organisation and structural integrity of the skeletal neuromuscular junction (NMJ), the target of botulinum neurotoxins (BoNTs), is unknown. OBJECTIVES To compare the organisation and structural integrity of skeletal NMJs from EGS horses, control horses and one horse with a presumptive diagnosis of botulism. STUDY DESIGN Blinded, retrospective case control. METHODS NMJs in samples of diaphragm or intercostal muscle from six EGS horses, three control horses and one equine botulism case were compared using electron microscopy, morphometry and confocal light microscopy. RESULTS A significantly higher percentage of EGS NMJs had abnormal morphology (EGS 72.2%, 95% CI 55.6-84.4; Controls 6.9%, 1.7-23.8; OR 35.1, 8.47-244.8; p < 0.001). EGS NMJs had a significantly lower mean volume fraction occupied by synaptic vesicles (SVs) (EGS 18.7%, 12.6-28.0; Controls 36.3%, 20.8-63.4; p = 0.024). EGS NMJs had evidence of accelerated SV exocytosis and SV depletion, accumulation of neurofilament-like material in terminal boutons and/or bouton degeneration. NMJs from the botulism horse had dense packing of SVs towards the presynaptic membrane active zone, consistent with BoNT intoxication, but had absence of the abnormalities identified in EGS NMJs. MAIN LIMITATIONS Group sizes were limited by difficulties obtaining suitably processed samples. Ages of control and EGS horses differed. Botulism was diagnosed based on clinical and post mortem findings. CONCLUSIONS EGS is associated with major changes in skeletal NMJ ultrastructure that are inconsistent with the effects of BoNTs. SV depletion may reflect increased exocytosis coupled with reduced repopulation of SVs via anterograde axonal transport and endocytosis, consistent with the action of an excitatory presynaptic toxin and/or neurotransmitter reuptake inhibitor. Skeletal NMJs represent a previously unrecognised target for the toxin that causes EGS.
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Affiliation(s)
- Bruce C McGorum
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - Tracey Davey
- Electron Microscopy Research Services, Newcastle University, Faculty of Medical Sciences, Newcastle upon Tyne, UK
| | - Miranda C M Dosi
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - John A Keen
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - Linda R Morrison
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - R Scott Pirie
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - Darren J Shaw
- Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Roslin, UK
| | - John B Harris
- Medical Toxicology Centre and Institute of Neuroscience, Newcastle University, Faculty of Medical Sciences, Newcastle upon Tyne, UK
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20
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Alipour M, Moeini M, Panahi M, Khashei Varnamkhasti K. Congenital myasthenic syndromes in two male siblings born to healthy consanguineous parents: a case report. Int J Neurosci 2024:1-3. [PMID: 38294717 DOI: 10.1080/00207454.2024.2313010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 01/27/2024] [Indexed: 02/01/2024]
Abstract
PURPOSE Congenital myasthenic syndromes include a wide range of early-onset genetic neuromuscular transmission disorders. Mutations in any one of genes coding for proteins related to the neuromuscular junction synaptic transmission function, can lead to such rare recessive inherited disorders. CASE PRESENTATION We present a report on recurrence of congenital myasthenic syndromes in two consecutive male siblings who were diagnosed on the basis of clinical findings. CONCLUSION To minimize risks for having affected child/children with autosomal recessive disorders, consanguineous couples must undergo genetic risk assessment, counseling, and screening.
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Affiliation(s)
- Marzyeh Alipour
- Department of Obstetrics and Gynecology, Imam Ali Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohsen Moeini
- Department of Pediatrics, Valiasr Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Masumeh Panahi
- Department of Obstetrics and Gynecology, Valiasr Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Khalil Khashei Varnamkhasti
- Department of Medical Laboratory Sciences, Faculty of Medicine, Kazerun Branch, Islamic Azad University, Kazerun, Iran
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21
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Hörner SJ, Couturier N, Hafner M, Rudolf R. Schwann cells in neuromuscular in vitro models. Biol Chem 2024; 405:25-30. [PMID: 37357580 DOI: 10.1515/hsz-2023-0172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 06/16/2023] [Indexed: 06/27/2023]
Abstract
Neuromuscular cell culture models are used to investigate synapse formation and function, as well as mechanisms of de-and regeneration in neuromuscular diseases. Recent developments including 3D culture technique and hiPSC technology have propelled their ability to complement insights from in vivo models. However, most cultures have not considered Schwann cells, the glial part of NMJs. In the following, a brief overview of different types of neuromuscular cocultures is provided alongside examples for studies that included Schwann cells. From these, findings concerning the effects of Schwann cells on those cultures are summarized and future lines of research are proposed.
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Affiliation(s)
- Sarah Janice Hörner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, D-69117 Heidelberg, Germany
- Center for Mass Spectrometry and Optical Spectroscopy, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
| | - Nathalie Couturier
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, D-69117 Heidelberg, Germany
- Center for Mass Spectrometry and Optical Spectroscopy, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
| | - Mathias Hafner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
- Institute of Medical Technology, Heidelberg University and Mannheim University of Applied Sciences, D-69117 Heidelberg, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, D-69117 Heidelberg, Germany
- Center for Mass Spectrometry and Optical Spectroscopy, Mannheim University of Applied Sciences, D-68163 Mannheim, Germany
- Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim Heidelberg University, D-68167 Mannheim, Germany
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22
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Liu Y, Lin W. Morphological and functional alterations of neuromuscular synapses in a mouse model of ACTA1 congenital myopathy. Hum Mol Genet 2024; 33:233-244. [PMID: 37883471 PMCID: PMC10800017 DOI: 10.1093/hmg/ddad183] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 10/09/2023] [Accepted: 10/20/2023] [Indexed: 10/28/2023] Open
Abstract
Mutations in skeletal muscle α-actin (Acta1) cause myopathies. In a mouse model of congenital myopathy, heterozygous Acta1 (H40Y) knock-in (Acta1+/Ki) mice exhibit features of human nemaline myopathy, including premature lethality, severe muscle weakness, reduced mobility, and the presence of nemaline rods in muscle fibers. In this study, we investigated the impact of Acta1 (H40Y) mutation on the neuromuscular junction (NMJ). We found that the NMJs were markedly fragmented in Acta1+/Ki mice. Electrophysiological analysis revealed a decrease in amplitude but increase in frequency of miniature end-plate potential (mEPP) at the NMJs in Acta1+/Ki mice, compared with those in wild type (Acta1+/+) mice. Evoked end-plate potential (EPP) remained similar at the NMJs in Acta1+/Ki and Acta1+/+ mice, but quantal content was increased at the NMJs in Acta1+/Ki, compared with Acta1+/+ mice, suggesting a homeostatic compensation at the NMJs in Acta1+/Ki mice to maintain normal levels of neurotransmitter release. Furthermore, short-term synaptic plasticity of the NMJs was compromised in Acta1+/Ki mice. Together, these results demonstrate that skeletal Acta1 H40Y mutation, albeit muscle-origin, leads to both morphological and functional defects at the NMJ.
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Affiliation(s)
- Yun Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390-9111, United States
| | - Weichun Lin
- Department of Neuroscience, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390-9111, United States
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23
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Iannuzzo F, Cicatiello AG, Sagliocchi S, Schiano E, Nappi A, Miro C, Stornaiuolo M, Mollica A, Tenore GC, Dentice M, Novellino E. Therapeutic Effect of an Ursolic Acid-Based Nutraceutical on Neuronal Regeneration after Sciatic Nerve Injury. Int J Mol Sci 2024; 25:902. [PMID: 38255977 PMCID: PMC10815361 DOI: 10.3390/ijms25020902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
Peripheral nerve injuries lead to severe functional impairments and long recovery times, with limited effectiveness and accessibility of current treatments. This has increased interest in natural bioactive compounds, such as ursolic acid (UA). Our study evaluated the effect of an oleolyte rich in UA from white grape pomace (WGPO) on neuronal regeneration in mice with induced sciatic nerve resection, administered concurrently with the induced damage (the WGPO group) and 10 days prior (the PRE-WGPO group). The experiment was monitored at two-time points (4 and 10 days) after injury. After 10 days, the WGPO group demonstrated a reduction in muscle atrophy, evidenced by an increased number and diameter of muscle fibers and a decreased Atrogin-1 and Murf-1 expression relative to the denervated control. It was also observed that 85.7% of neuromuscular junctions (NMJs) were fully innervated, as indicated by the colocalization of α-bungarotoxin and synaptophysin, along with the significant modulation of Oct-6 and S-100. The PRE-WGPO group showed a more beneficial effect on nerve fiber reformation, with a significant increase in myelin protein zero and 95.2% fully innervated NMJs, and a pro-hypertrophic effect in resting non-denervated muscles. Our findings suggest WGPO as a potential treatment for various conditions that require the repair of nerve and muscle injuries.
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Affiliation(s)
- Fortuna Iannuzzo
- Department of Pharmacy, G. d’Annunzio University of Chieti-Pescara, 66100 Chieti, Italy; (F.I.); (A.M.)
| | - Annunziata Gaetana Cicatiello
- Department of Clinical Medicine and Surgery, University of Naples Federico II, 80131 Napoli, Italy; (A.G.C.); (S.S.); (A.N.); (C.M.)
| | - Serena Sagliocchi
- Department of Clinical Medicine and Surgery, University of Naples Federico II, 80131 Napoli, Italy; (A.G.C.); (S.S.); (A.N.); (C.M.)
| | - Elisabetta Schiano
- Healthcare Food Research Center, Inventia Biotech s.r.l., S. S. Sannitica, 81020 Caserta, Italy; (E.S.); (E.N.)
| | - Annarita Nappi
- Department of Clinical Medicine and Surgery, University of Naples Federico II, 80131 Napoli, Italy; (A.G.C.); (S.S.); (A.N.); (C.M.)
| | - Caterina Miro
- Department of Clinical Medicine and Surgery, University of Naples Federico II, 80131 Napoli, Italy; (A.G.C.); (S.S.); (A.N.); (C.M.)
| | - Mariano Stornaiuolo
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 59, 80131 Napoli, Italy; (M.S.); (G.C.T.)
| | - Adriano Mollica
- Department of Pharmacy, G. d’Annunzio University of Chieti-Pescara, 66100 Chieti, Italy; (F.I.); (A.M.)
| | - Gian Carlo Tenore
- Department of Pharmacy, University of Naples Federico II, Via Domenico Montesano 59, 80131 Napoli, Italy; (M.S.); (G.C.T.)
| | - Monica Dentice
- Department of Clinical Medicine and Surgery, University of Naples Federico II, 80131 Napoli, Italy; (A.G.C.); (S.S.); (A.N.); (C.M.)
| | - Ettore Novellino
- Healthcare Food Research Center, Inventia Biotech s.r.l., S. S. Sannitica, 81020 Caserta, Italy; (E.S.); (E.N.)
- Faculty of Medicine and Surgery, Catholic University of the Sacred Heart, 00168 Roma, Italy
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24
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Willoughby DS, Florez C, Davis J, Keratsopoulos N, Bisher M, Parra M, Taylor L. Decreased Neuromuscular Function and Muscle Quality along with Increased Systemic Inflammation and Muscle Proteolysis Occurring in the Presence of Decreased Estradiol and Protein Intake in Early to Intermediate Post-Menopausal Women. Nutrients 2024; 16:197. [PMID: 38257090 PMCID: PMC10819584 DOI: 10.3390/nu16020197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/05/2024] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
Menopause causes a reduction in estradiol (E2) and may be associated with neuromuscular degeneration. Compared to pre-menopausal (PRE-M) women, this study sought to determine dietary protein intake and whether lower levels of circulating E2 in post-menopausal women (POST-M) were occurring alongside increased levels of biomarkers of axonal and neuromuscular junction degeneration (NMJ), inflammation, muscle protein degradation, and reduced indices of muscle quality and performance. Employing a cross-sectional design, PRE-M (n = 6) and POST-M (n = 6) dietary analysis data were collected and participants then donated a blood and urine sample followed by assessments for body composition, motor unit activation, and muscle performance. Independent group t-tests were performed to determine differences between groups (p ≤ 0.05). In POST-M women, E2, motor unit activity, muscle quality, and muscle performance were significantly less than those for PRE-M women; however, the levels of c-terminal fragment of agrin, tumor necrosis factor-α, and urinary titin were significantly greater (p < 0.05). POST-M women were also shown to be ingesting fewer total calories and less protein than PRE-M (p < 0.05). Reduced E2 and dietary protein intake in POST-M women occurs in conjunction with increased levels of biomarkers of NMJ degradation, inflammation, and muscle proteolysis, which may be associated with reduced motor unit activation and muscle quality.
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Affiliation(s)
- Darryn S. Willoughby
- School of Health Professions, University of Mary Hardin-Baylor, Belton, TX 76513, USA
| | - Christine Florez
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX 76513, USA; (C.F.)
| | - Jaci Davis
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX 76513, USA; (C.F.)
| | - Nikolas Keratsopoulos
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX 76513, USA; (C.F.)
| | - Morgan Bisher
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX 76513, USA; (C.F.)
| | - Mandy Parra
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX 76513, USA; (C.F.)
| | - Lemuel Taylor
- School of Health Professions, University of Mary Hardin-Baylor, Belton, TX 76513, USA
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25
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Polavarapu K, Sunitha B, Töpf A, Preethish-Kumar V, Thompson R, Vengalil S, Nashi S, Bardhan M, Sanka SB, Huddar A, Unnikrishnan G, Arunachal G, Girija MS, Porter A, Azuma Y, Lorenzoni PJ, Baskar D, Anjanappa RM, Keertipriya M, Padmanabh H, Harikrishna GV, Laurie S, Matalonga L, Horvath R, Nalini A, Lochmüller H. Clinical and genetic characterisation of a large Indian congenital myasthenic syndrome cohort. Brain 2024; 147:281-296. [PMID: 37721175 PMCID: PMC10766255 DOI: 10.1093/brain/awad315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/20/2023] [Accepted: 08/10/2023] [Indexed: 09/19/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a rare group of inherited disorders caused by gene defects associated with the neuromuscular junction and potentially treatable with commonly available medications such as acetylcholinesterase inhibitors and β2 adrenergic receptor agonists. In this study, we identified and genetically characterized the largest cohort of CMS patients from India to date. Genetic testing of clinically suspected patients evaluated in a South Indian hospital during the period 2014-19 was carried out by standard diagnostic gene panel testing or using a two-step method that included hotspot screening followed by whole-exome sequencing. In total, 156 genetically diagnosed patients (141 families) were characterized and the mutational spectrum and genotype-phenotype correlation described. Overall, 87 males and 69 females were evaluated, with the age of onset ranging from congenital to fourth decade (mean 6.6 ± 9.8 years). The mean age at diagnosis was 19 ± 12.8 (1-56 years), with a mean diagnostic delay of 12.5 ± 9.9 (0-49 years). Disease-causing variants in 17 CMS-associated genes were identified in 132 families (93.6%), while in nine families (6.4%), variants in genes not associated with CMS were found. Overall, postsynaptic defects were most common (62.4%), followed by glycosylation defects (21.3%), synaptic basal lamina genes (4.3%) and presynaptic defects (2.8%). Other genes found to cause neuromuscular junction defects (DES, TEFM) in our cohort accounted for 2.8%. Among the individual CMS genes, the most commonly affected gene was CHRNE (39.4%), followed by DOK7 (14.4%), DPAGT1 (9.8%), GFPT1 (7.6%), MUSK (6.1%), GMPPB (5.3%) and COLQ (4.5%). We identified 22 recurrent variants in this study, out of which eight were found to be geographically specific to the Indian subcontinent. Apart from the known common CHRNE variants p.E443Kfs*64 (11.4%) and DOK7 p.A378Sfs*30 (9.3%), we identified seven novel recurrent variants specific to this cohort, including DPAGT1 p.T380I and DES c.1023+5G>A, for which founder haplotypes are suspected. This study highlights the geographic differences in the frequencies of various causative CMS genes and underlines the increasing significance of glycosylation genes (DPAGT1, GFPT1 and GMPPB) as a cause of neuromuscular junction defects. Myopathy and muscular dystrophy genes such as GMPPB and DES, presenting as gradually progressive limb girdle CMS, expand the phenotypic spectrum. The novel genes MACF1 and TEFM identified in this cohort add to the expanding list of genes with new mechanisms causing neuromuscular junction defects.
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Affiliation(s)
- Kiran Polavarapu
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Balaraju Sunitha
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Veeramani Preethish-Kumar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, Neurofoundation, Salem, Tamil Nadu 636009, India
| | - Rachel Thompson
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Seena Vengalil
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Mainak Bardhan
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Sai Bhargava Sanka
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Akshata Huddar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, St Johns Medical College Hospital, Bangalore 560034, India
| | - Gopikrishnan Unnikrishnan
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, Amruta Institute of Medical Sciences, Kochi 682041, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru 560029, India
| | - Manu Santhappan Girija
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Anna Porter
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Paulo José Lorenzoni
- Neuromuscular Disorders Division, Service of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal do Paraná, Rua General Carneiro, Curitiba - PR 80060-900, Brazil
| | - Dipti Baskar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Ram Murthy Anjanappa
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Madassu Keertipriya
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Hansashree Padmanabh
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | | | - Steve Laurie
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
| | - Leslie Matalonga
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK
| | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON K1H 8M5, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center–University of Freiburg, Faculty of Medicine, Freiburg 79110, Germany
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26
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Rudolf R. Myosin Va: Capturing cAMP for synaptic plasticity. Front Physiol 2024; 14:1342994. [PMID: 38239886 PMCID: PMC10794446 DOI: 10.3389/fphys.2023.1342994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 12/12/2023] [Indexed: 01/22/2024] Open
Abstract
The plus-end directed actin-dependent motor protein, myosin Va, is of particular relevance for outward vesicular protein trafficking and for restraining specific cargo vesicles within the actin cortex. The latter is a preferred site of cAMP production, and the specificity of cAMP signaling is largely mediated through the formation of microdomains that spatially couple localized metabotropic receptor activity and cAMP production to selected effectors and downstream targets. This review summarizes the core literature on the role of myosin Va for the creation of such a cAMP microdomain at the mammalian nerve-muscle synapse that serves the activity-dependent recycling of nicotinic acetylcholine receptors (nAChRs)-a principal ligand-gated ion channel which is imperative for voluntary muscle contraction. It is discussed that i) the nerve-muscle synapse is a site with a unique actin-dependent microstructure, ii) myosin Va and protein kinase A regulatory subunit Iα as well as nAChR and its constitutive binding partner, rapsyn, colocalize in endocytic/recycling vesicles near the postsynaptic membrane, and iii) impairment of myosin Va or displacement of protein kinase A regulatory subunit Iα leads to the loss of nAChR stability. Regulation of this signaling process and underlying basic pieces of machinery were covered in previous articles, to which the present review refers.
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Affiliation(s)
- Rüdiger Rudolf
- Center for Mass Spectrometry and Optical Spectroscopy (CeMOS), Mannheim University of Applied Sciences, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
- Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany
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27
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Miao Y, Xie L, Song J, Cai X, Yang J, Ma X, Chen S, Xie P. Unraveling the causes of sarcopenia: Roles of neuromuscular junction impairment and mitochondrial dysfunction. Physiol Rep 2024; 12:e15917. [PMID: 38225199 PMCID: PMC10789655 DOI: 10.14814/phy2.15917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/11/2023] [Accepted: 12/22/2023] [Indexed: 01/17/2024] Open
Abstract
Sarcopenia is a systemic skeletal muscle disease characterized by a decline in skeletal muscle mass and function. Originally defined as an age-associated condition, sarcopenia presently also encompasses muscular atrophy due to various pathological factors, such as intensive care unit-acquired weakness, inactivity, and malnutrition. The exact pathogenesis of sarcopenia is still unknown; herein, we review the pathological roles of the neuromuscular junction and mitochondria in this condition. Sarcopenia is caused by complex and interdependent pathophysiological mechanisms, including aging, neuromuscular junction impairment, mitochondrial dysfunction, insulin resistance, lipotoxicity, endocrine factors, oxidative stress, and inflammation. Among these, neuromuscular junction instability and mitochondrial dysfunction are particularly significant. Dysfunction in neuromuscular junction can lead to muscle weakness or paralysis. Mitochondria, which are plentiful in neurons and muscle fibers, play an important role in neuromuscular junction transmission. Therefore, impairments in both mitochondria and neuromuscular junction may be one of the key pathophysiological mechanisms leading to sarcopenia. Moreover, this article explores the structural and functional alterations in the neuromuscular junction and mitochondria in sarcopenia, suggesting that a deeper understanding of these changes could provide valuable insights for the prevention or treatment of sarcopenia.
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Affiliation(s)
- Yanmei Miao
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
| | - Leiyu Xie
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
| | - Jiamei Song
- Department of Nursing of Affiliated HospitalZunyi Medical UniversityZunyiChina
| | - Xing Cai
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
| | - Jinghe Yang
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
- Department of The First Clinical CollegeZunyi Medical UniversityZunyiChina
| | - Xinglong Ma
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
| | - Shaolin Chen
- Department of Nursing of Affiliated HospitalZunyi Medical UniversityZunyiChina
| | - Peng Xie
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi)Zunyi Medical UniversityZunyiChina
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28
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Affiliation(s)
- L Ignacio Cortínez
- División Anestesiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago de, Chile
| | - Brian J Anderson
- Department of Anesthesiology, University of Auckland, Auckland, New Zealand
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29
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Di Natale MR, Hunne B, Stebbing MJ, Wang X, Liu Z, Furness JB. Characterization of neuromuscular transmission and projections of muscle motor neurons in the rat stomach. Am J Physiol Gastrointest Liver Physiol 2024; 326:G78-G93. [PMID: 37987773 DOI: 10.1152/ajpgi.00194.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 11/22/2023]
Abstract
The stomach is the primary reservoir of the gastrointestinal tract, where ingested content is broken down into small particles. Coordinated relaxation and contraction is essential for rhythmic motility and digestion, but how the muscle motor innervation is organized to provide appropriate graded regional control is not established. In this study, we recorded neuromuscular transmission to the circular muscle using intracellular microelectrodes to investigate the spread of the influence of intrinsic motor neurons. In addition, microanatomical investigations of neuronal projections and pharmacological analysis were conducted to investigate neuromuscular relationships. We found that inhibitory neurotransmission to the circular muscle is graded with stimulus strength and circumferential distance from the stimulation site. The influence of inhibitory neurons declined between 1 and 11 mm from the stimulation site. In the antrum, corpus, and fundus, the declines at 11 mm were about 20%, 30%, and 50%, respectively. Stimulation of inhibitory neurons elicited biphasic hyperpolarizing potentials often followed by prolonged depolarizing events in the distal stomach, but only hyperpolarizing events in the proximal stomach. Excitatory neurotransmission influence varied greatly between proximal stomach, where depolarizing events occurred, and distal stomach, where no direct electrical effects in the muscle were observed. Structural studies using microlesion surgeries confirmed a dominant circumferential projection. We conclude that motor neuron influences extend around the gastric circumference, that the effectiveness can be graded by the recruitment of different numbers of motor neuron nerve terminals to finely control gastric motility, and that the ways in which the neurons influence the muscle differ between anatomical regions.NEW & NOTEWORTHY This study provides a detailed mapping of nerve transmission to the circular muscle of the different anatomical regions of rat stomach. It shows that excitatory and inhibitory influences extend around the gastric circumference and that there is a summation of neural influence that allows for finely graded control of muscle tension and length. Nerve-mediated electrical events are qualitatively and quantitatively different between regions, for example, excitatory neurons have direct effects on fundus but not antral muscle.
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Affiliation(s)
- Madeleine R Di Natale
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Billie Hunne
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Martin J Stebbing
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Xiaokai Wang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, United States
| | - Zhongming Liu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, United States
| | - John B Furness
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Victoria, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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30
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Martínez-Sánchez JE, Cárdenas Y, Trujillo X, Ríos-Silva M, Díaz-Reval MI, Bricio-Barrios JA, Muñiz J, Alcaraz-Siqueiros J, Huerta M. Increased Frequency of Giant Miniature End-Plate Potentials at the Neuromuscular Junction in Diabetic Rats. Biomedicines 2023; 12:68. [PMID: 38255175 PMCID: PMC10813272 DOI: 10.3390/biomedicines12010068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/20/2023] [Accepted: 12/23/2023] [Indexed: 01/24/2024] Open
Abstract
There is a need for research addressing the functional characteristics of the motor end-plate in diabetes to identify mechanisms contributing to neuromuscular dysfunction. Here, we investigated the effect of diabetes on spontaneous acetylcholine release in the rat neuromuscular junction. We studied two randomized groups of male Wistar rats (n = 7 per group, 350 ± 50 g, 12-16 weeks of age): one with streptozotocin-induced experimental diabetes, and a healthy control group without diabetes. After 8 weeks of monitoring after diabetes induction, rats in both groups were anesthetized with pentobarbital. Then, the diaphragm muscle was dissected for electrophysiological recordings of miniature end-plate potentials (MEPPs) using a single electrode located at the region of the muscle end-plate. All experiments were conducted at environmental temperature (20-22 °C) in rat Ringer solution with constant bubbling carbogen (95% O2, 5% CO2). Compared to healthy controls, in the diaphragm neuromuscular end-plate derived from diabetic rats, the MEPPs were higher in amplitude and frequency, and the proportion of giant MEPPs was elevated (7.09% vs. 1.4% in controls). Our results showed that diabetes affected the acetylcholine MEPP pattern and increased the number of giant potentials compared to healthy controls.
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Affiliation(s)
- Julián Elías Martínez-Sánchez
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
| | - Yolitzy Cárdenas
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
| | - Xóchitl Trujillo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
| | - Mónica Ríos-Silva
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima—CONAHCyT, Av. 25 de Julio 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico
| | - M. Irene Díaz-Reval
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
| | - Jaime Alberto Bricio-Barrios
- Facultad de Medicina, Universidad de Colima, Av. Universidad #333, Col. Las Víboras, Colima 28040, Colima, Mexico;
| | - Jesús Muñiz
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
| | - Julio Alcaraz-Siqueiros
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad de Colima, Km 40 Autopista Colima-Manzanillo, Crucero de Tecomán, Tecomán 28930, Colima, Mexico
| | - Miguel Huerta
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio # 965, Col. Villas San Sebastián, Colima 28045, Colima, Mexico; (J.E.M.-S.); (X.T.)
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Urzi A, Lahmann I, Nguyen LVN, Rost BR, García-Pérez A, Lelievre N, Merritt-Garza ME, Phan HC, Bassell GJ, Rossoll W, Diecke S, Kunz S, Schmitz D, Gouti M. Efficient generation of a self-organizing neuromuscular junction model from human pluripotent stem cells. Nat Commun 2023; 14:8043. [PMID: 38114482 PMCID: PMC10730704 DOI: 10.1038/s41467-023-43781-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023] Open
Abstract
The complex neuromuscular network that controls body movements is the target of severe diseases that result in paralysis and death. Here, we report the development of a robust and efficient self-organizing neuromuscular junction (soNMJ) model from human pluripotent stem cells that can be maintained long-term in simple adherent conditions. The timely application of specific patterning signals instructs the simultaneous development and differentiation of position-specific brachial spinal neurons, skeletal muscles, and terminal Schwann cells. High-content imaging reveals self-organized bundles of aligned muscle fibers surrounded by innervating motor neurons that form functional neuromuscular junctions. Optogenetic activation and pharmacological interventions show that the spinal neurons actively instruct the synchronous skeletal muscle contraction. The generation of a soNMJ model from spinal muscular atrophy patient-specific iPSCs reveals that the number of NMJs and muscle contraction is severely affected, resembling the patient's pathology. In the future, the soNMJ model could be used for high-throughput studies in disease modeling and drug development. Thus, this model will allow us to address unmet needs in the neuromuscular disease field.
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Affiliation(s)
- Alessia Urzi
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Ines Lahmann
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Lan Vi N Nguyen
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Benjamin R Rost
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Angélica García-Pérez
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Noemie Lelievre
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Megan E Merritt-Garza
- Department of Cell Biology, Laboratory for Translational Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Han C Phan
- Department of Pediatrics, University of Alabama, Birmingham, AL, 35294, USA
| | - Gary J Bassell
- Department of Cell Biology, Laboratory for Translational Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Wilfried Rossoll
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Sebastian Diecke
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Technology Platform Pluripotent Stem Cells, 13125, Berlin, Germany
| | - Severine Kunz
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Technology Platform Electron Microscopy, 13125, Berlin, Germany
| | - Dietmar Schmitz
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Berlin Institute of Health, NeuroCure Cluster of Excellence, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Mina Gouti
- Stem Cell Modeling of Development & Disease Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany.
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Hayashi M. Pathophysiology of Childhood-Onset Myasthenia: Abnormalities of Neuromuscular Junction and Autoimmunity and Its Background. Pathophysiology 2023; 30:599-617. [PMID: 38133144 PMCID: PMC10747330 DOI: 10.3390/pathophysiology30040043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
The pathophysiology of myasthenia gravis (MG) has been largely elucidated over the past half century, and treatment methods have advanced. However, the number of cases of childhood-onset MG is smaller than that of adult MG, and the treatment of childhood-onset MG has continued to be based on research in the adult field. Research on pathophysiology and treatment methods that account for the unique growth and development of children is now desired. According to an epidemiological survey conducted by the Ministry of Health, Labour and Welfare of Japan, the number of patients with MG by age of onset in Japan is high in early childhood. In recent years, MG has been reported from many countries around the world, but the pattern of the number of patients by age of onset differs between East Asia and Western Europe, confirming that the Japanese pattern is common in East Asia. Furthermore, there are racial differences in autoimmune MG and congenital myasthenic syndromes according to immunogenetic background, and their pathophysiology and relationships are gradually becoming clear. In addition, treatment options are also recognized in different regions of the world. In this review article, I will present recent findings focusing on the differences in pathophysiology.
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Affiliation(s)
- Masatoshi Hayashi
- Department of Pediatrics, Uwajima City Hospital, Uwajima 798-8510, Japan
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Mishra AK, Varma A. Myasthenia Gravis: A Systematic Review. Cureus 2023; 15:e50017. [PMID: 38186498 PMCID: PMC10767470 DOI: 10.7759/cureus.50017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/06/2023] [Indexed: 01/09/2024] Open
Abstract
Myasthenia gravis (MG), a rare disease, is the most common neuromuscular junction problem. It's the quintessential autoimmune disease with ocular, bulbar, respiratory, axial, and limb muscles exhibiting a typical fatigable weakening due to the development of antibodies against the acetylcholine receptor (AChR). Infections, stress, surgeries, thymus gland anomalies, and pharmaceutical side effects can also cause it. Ocular symptoms are initially experienced by most of the sufferers. The majority of the sufferers will go through at least one episode of symptom exacerbation during their illness. The immune system in MG interferes with nerve-muscle communication, causing muscles to become weak and tired quickly. The actual cause is not yet known, but a problem in the thymus gland may be the cause. In a person suffering from this disease, the size of the thymus becomes larger than normal, which is also called thymic hyperplasia. It is more common for women to have early-onset MG (EOMG) than for males to have late-onset MG (LOMG). Merely clinical evidence, encompassing the patients' medical history and physical indications of fluctuating muscle weakness in a specific region, is utilized to diagnose MG. Complementary diagnostic procedures and lab techniques aid in confirming the synaptic dysfunction and characterizing its kind and degree. Early diagnosis and the availability of effective treatments have reduced the burden of severe impairment and high mortality previously associated with MG. Current immunomodulation-based therapies come with side effects brought on by persistent immune suppression. Improved knowledge of this relatively uncommon but curable condition is required among primary carers. The objective of this review is to provide information about MG and to help people recognize its symptoms and start treatment without panic so that the progression of this disease can be stopped and complications can be avoided.
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Affiliation(s)
- Aneesh K Mishra
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Anuj Varma
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
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Luo J, Sun A, Yu Y, Pei Y, Zuo Y, Hu Z. Periplocoside P affects synaptic transmission at the neuromuscular junction and reduces synaptic excitability in Drosophila melanogaster by inhibiting V-ATPase. Pest Manag Sci 2023; 79:5044-5052. [PMID: 37556562 DOI: 10.1002/ps.7705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND Periplocoside P (PSP) is a major component of Periploca sepium Bunge known for its potent insecticidal activity. V-Type adenosine triphosphatase (V-ATPase), which is widely distributed in the cytoplasmic membranes and organelles of eukaryotic cells, plays a crucial role in synaptic excitability conduction. Previous research has shown that PSP targets the apical membrane of goblet cells in the insect midgut. However, the effects of PSP on synaptic transmission at the neuromuscular junction are often overlooked. RESULTS The bioassay revealed that Drosophila adults with different genetic backgrounds showed varying levels of susceptibility to PSP in the order: parats1 > parats1 ;DSC1-/- ≈ w1118 > DSC1-/- . Intracellular electrode recording demonstrated that PSP, similar to bafilomycin A1, had an impact on the amplitude of the excitatory junction potential (EJP) and accelerated excitability decay. Furthermore, the alteration in EJP amplitude is concentration-dependent. Another surprising discovery was that the knockout DSC1 channel showed insensitivity to PSP. CONCLUSION Our findings confirm that PSP can influence synaptic transmission at the neuromuscular junction of Drosophila larvae by targeting V-ATPase. These results provide a basis for investigating the mechanism of action of PSP and its potential application in designing novel insecticides. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Jiaojiao Luo
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Anqi Sun
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yang Yu
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yakun Pei
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yayun Zuo
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F Univeristy, Yangling, Shaanxi, China
| | - Zhaonong Hu
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F Univeristy, Yangling, Shaanxi, China
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Kouyoumdjian JA, Estephan EDP. Electrophysiological evaluation of the neuromuscular junction: a brief review. Arq Neuropsiquiatr 2023; 81:1040-1052. [PMID: 38157872 PMCID: PMC10756823 DOI: 10.1055/s-0043-1777749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
The nerve terminal and muscle membrane compose the neuromuscular junction. After opening the voltage-gated calcium channels, action potentials from the motor axons provoke a cascade for the acetylcholine release from synaptic vesicles to the synaptic cleft, where it binds to its receptor at the muscle membrane for depolarization. Low amplitude compound muscle action potential typically presents in presynaptic disorders, increasing by more than 100% after a 10-second effort in the Lambert-Eaton myasthenic syndrome and less in botulism. Needle electromyography may show myopathic motor unit action potentials and morphological instability ("jiggle") due to impulse blocking. Low-frequency repetitive nerve stimulation (RNS) is helpful in postsynaptic disorders, such as myasthenia gravis and most congenital myasthenic syndromes, where the number of functioning acetylcholine receptors is reduced. Low-frequency RNS with a decrement >10% is abnormal when comparing the 4th to the first compound muscle action potential amplitude. High-frequency RNS is helpful in presynaptic disorders like Lambert-Eaton myasthenic syndrome, botulism, and some rare congenital myasthenic syndromes. The high-frequency RNS releases more calcium, increasing the acetylcholine with a compound muscle action potential increment. Concentric needle records apparent single-fiber action potentials (spikes). A voluntary activation measures the jitter between spikes from two endplates. An electrical activation measures the jitter of one spike (one endplate). The jitter is the most sensitive test for detecting a neuromuscular junction dysfunction. Most neuromuscular junction disorders are responsive to treatment.
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Affiliation(s)
- João Aris Kouyoumdjian
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
| | - Eduardo de Paula Estephan
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
- Universidade de São Paulo, Departamento de Neurologia, São Paulo SP, Brazil.
- Faculdade de Medicina Santa Marcelina, São Paulo SP, Brazil.
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36
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Kim H, Kim GS, Hyun SH, Kim E. Advancements in 2D and 3D In Vitro Models for Studying Neuromuscular Diseases. Int J Mol Sci 2023; 24:17006. [PMID: 38069329 PMCID: PMC10707046 DOI: 10.3390/ijms242317006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Neuromuscular diseases (NMDs) are a genetically or clinically heterogeneous group of diseases that involve injury or dysfunction of neuromuscular tissue components, including peripheral motor neurons, skeletal muscles, and neuromuscular junctions. To study NMDs and develop potential therapies, remarkable progress has been made in generating in vitro neuromuscular models using engineering approaches to recapitulate the complex physical and biochemical microenvironments of 3D human neuromuscular tissues. In this review, we discuss recent studies focusing on the development of in vitro co-culture models of human motor neurons and skeletal muscles, with the pros and cons of each approach. Furthermore, we explain how neuromuscular in vitro models recapitulate certain aspects of specific NMDs, including amyotrophic lateral sclerosis and muscular dystrophy. Research on neuromuscular organoids (NMO) will continue to co-develop to better mimic tissues in vivo and will provide a better understanding of the development of the neuromuscular tissue, mechanisms of NMD action, and tools applicable to preclinical studies, including drug screening and toxicity tests.
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Affiliation(s)
- Haneul Kim
- Laboratory of Molecular Diagnostics and Cell Biology, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Republic of Korea;
| | - Gon Sup Kim
- Research Institute of Life Science, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Republic of Korea;
| | - Sang-Hwan Hyun
- Laboratory of Veterinary Embryology and Biotechnology, Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea;
- Institute for Stem Cell & Regenerative Medicine, Chungbuk National University, Chengju 28644, Republic of Korea
- Graduate School of Veterinary Biosecurity and Protection, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Eunhye Kim
- Laboratory of Molecular Diagnostics and Cell Biology, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Republic of Korea;
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37
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Pereira Santos R, Nardi AE, da Mota Gomes M. [How studies on curare contributed to the development of neurophysiological research in Brazil]. Biol Aujourdhui 2023; 217:245-252. [PMID: 38018952 DOI: 10.1051/jbio/2023025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Indexed: 11/30/2023]
Abstract
Curare is a poison obtained from different species of plants in South America, which was used in arrows by the natives. Its lethal paralyzing potential and mechanism of action began to be explored in the 19th century. In this article, we highlight the research on this poison and the fruitful exchanges between the Brazilian Emperor Dom Pedro II and the researchers João Baptista de Lacerda, Louis Couty and Alfred Vulpian who contributed to the development of experimental neurophysiology in Brazil. Vulpian found that curare does not affect the nerve itself, but acts between the nerves and the muscle, through a "ligand substance" - this Vulpian's pioneering concept is often wrongly attributed to Claude Bernard. These prestigious scientists contributed to the transnational circulation of knowledge that later yielded in the preparation of curare purified extract used for convulsive therapy and anesthesia.
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Affiliation(s)
- Roberto Pereira Santos
- Service of Neurology, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Rio de Janeiro, Brésil
| | - Antonio Egídio Nardi
- Laboratory of History of Psychiatry, Neurology, and Mental Health, Institute of Psychiatry Faculty of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brésil
| | - Marleide da Mota Gomes
- Laboratory of History of Psychiatry, Neurology, and Mental Health, Institute of Psychiatry Faculty of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brésil
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38
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Christophers B, Leahy SN, Soffar DB, von Saucken VE, Broadie K, Baylies MK. Muscle cofilin alters neuromuscular junction postsynaptic development to strengthen functional neurotransmission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568166. [PMID: 38045306 PMCID: PMC10690168 DOI: 10.1101/2023.11.21.568166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Cofilin, an actin severing protein, plays critical roles in muscle sarcomere addition and maintenance. Our previous work has shown Drosophila cofilin (DmCFL) knockdown causes progressive deterioration of muscle structure and function and produces features seen in nemaline myopathy (NM) caused by cofilin mutations. We hypothesized that disruption of actin cytoskeleton dynamics by DmCFL knockdown would impact other aspects of muscle development, and, thus, conducted an RNA sequencing analysis which unexpectedly revealed upregulated expression of numerous neuromuscular junction (NMJ) genes. We found that DmCFL is enriched in the muscle postsynaptic compartment and that DmCFL deficiency causes F-actin disorganization in this subcellular domain prior to the sarcomere defects observed later in development. Despite NMJ gene expression changes, we found no significant changes in gross presynaptic Bruchpilot active zones or total postsynaptic glutamate receptor levels. However, DmCFL knockdown results in mislocalization of glutamate receptors containing the GluRIIA subunit in more deteriorated muscles and neurotransmission strength is strongly impaired. These findings expand our understanding of cofilin's roles in muscle to include NMJ structural development and suggest that NMJ defects may contribute to NM pathophysiology.
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Affiliation(s)
- Briana Christophers
- Weill Cornell-Rockefeller-Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Shannon N Leahy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - David B Soffar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Victoria E von Saucken
- Weill Cornell-Rockefeller-Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Kennedy Center for Research on Human Development, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - Mary K Baylies
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
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39
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Shefner JM, Musaro A, Ngo ST, Lunetta C, Steyn FJ, Robitaille R, De Carvalho M, Rutkove S, Ludolph AC, Dupuis L. Skeletal muscle in amyotrophic lateral sclerosis. Brain 2023; 146:4425-4436. [PMID: 37327376 PMCID: PMC10629757 DOI: 10.1093/brain/awad202] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/16/2023] [Accepted: 05/30/2023] [Indexed: 06/18/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS), the major adult-onset motor neuron disease, has been viewed almost exclusively as a disease of upper and lower motor neurons, with muscle changes interpreted as a consequence of the progressive loss of motor neurons and neuromuscular junctions. This has led to the prevailing view that the involvement of muscle in ALS is only secondary to motor neuron loss. Skeletal muscle and motor neurons reciprocally influence their respective development and constitute a single functional unit. In ALS, multiple studies indicate that skeletal muscle dysfunction might contribute to progressive muscle weakness, as well as to the final demise of neuromuscular junctions and motor neurons. Furthermore, skeletal muscle has been shown to participate in disease pathogenesis of several monogenic diseases closely related to ALS. Here, we move the narrative towards a better appreciation of muscle as a contributor of disease in ALS. We review the various potential roles of skeletal muscle cells in ALS, from passive bystanders to active players in ALS pathophysiology. We also compare ALS to other motor neuron diseases and draw perspectives for future research and treatment.
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Affiliation(s)
- Jeremy M Shefner
- Barrow Neurological Institute, Phoenix, AZ, USA
- College of Medicine, University of Arizona, Phoenix, AZ, USA
- College of Medicine, Creighton University, Phoenix, AZ, USA
| | - Antonio Musaro
- DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia—Fondazione Cenci Bolognetti, Scuola Superiore di Studi Avanzati Sapienza (SSAS), Rome, Italy
| | - Shyuan T Ngo
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Christian Lunetta
- Neurorehabilitation Department, Istituti Clinici Scientifici Maugeri IRCCS, Milan, Italy
| | - Frederik J Steyn
- Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Richard Robitaille
- Département de neurosciences, CIRCA, Université de Montréal, Montréal H7G 1T7, Canada
| | - Mamede De Carvalho
- Instituto de Fisiologia, Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Seward Rutkove
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Albert C Ludolph
- Department of Neurology, University of Ulm, Ulm, Germany
- Deutsches Zentrum für neurodegenerative Erkrankungen (DZNE), Ulm, Germany
| | - Luc Dupuis
- Université de Strasbourg, Inserm, UMR-S1118, Mécanismes centraux et périphériques de la neurodégénérescence, CRBS, Strasbourg, France
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40
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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Aimino MA, Humenik J, Parisi MJ, Duhart JC, Mosca TJ. SynLight: a bicistronic strategy for simultaneous active zone and cell labeling in the Drosophila nervous system. G3 (Bethesda) 2023; 13:jkad221. [PMID: 37757863 PMCID: PMC10627267 DOI: 10.1093/g3journal/jkad221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 07/14/2023] [Accepted: 09/17/2023] [Indexed: 09/29/2023]
Abstract
At synapses, chemical neurotransmission mediates the exchange of information between neurons, leading to complex movement, behaviors, and stimulus processing. The immense number and variety of neurons within the nervous system make discerning individual neuron populations difficult, necessitating the development of advanced neuronal labeling techniques. In Drosophila, Bruchpilot-Short and mCD8-GFP, which label presynaptic active zones and neuronal membranes, respectively, have been widely used to study synapse development and organization. This labeling is often achieved via the expression of 2 independent constructs by a single binary expression system, but expression can weaken when multiple transgenes are expressed by a single driver. Recent work has sought to circumvent these drawbacks by developing methods that encode multiple proteins from a single transcript. Self-cleaving peptides, specifically 2A peptides, have emerged as effective sequences for accomplishing this task. We leveraged 2A ribosomal skipping peptides to engineer a construct that produces both Bruchpilot-Short-mStraw and mCD8-GFP from the same mRNA, which we named SynLight. Using SynLight, we visualized the putative synaptic active zones and membranes of multiple classes of olfactory, visual, and motor neurons and observed the correct separation of signal, confirming that both proteins are being generated separately. Furthermore, we demonstrate proof of principle by quantifying synaptic puncta number and neurite volume in olfactory neurons and finding no difference between the synapse densities of neurons expressing SynLight or neurons expressing both transgenes separately. At the neuromuscular junction, we determined that the synaptic puncta number labeled by SynLight was comparable to the endogenous puncta labeled by antibody staining. Overall, SynLight is a versatile tool for examining synapse density in any nervous system region of interest and allows new questions to be answered about synaptic development and organization.
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Affiliation(s)
- Michael A Aimino
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Jesse Humenik
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Michael J Parisi
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Juan Carlos Duhart
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
| | - Timothy J Mosca
- Department of Neuroscience, Vickie and Jack Farber Institute of Neuroscience, Thomas Jefferson University, Bluemle Life Sciences Building, Philadelphia, PA 19107, USA
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He Y, Wang HP, Pan FY, Xu SH, Gao YF. Plasticity changes in neuromuscular junction morphology and related regulatory proteins in the hibernating ground squirrel. J Appl Physiol (1985) 2023; 135:1082-1091. [PMID: 37795532 DOI: 10.1152/japplphysiol.00334.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/06/2023] Open
Abstract
Skeletal muscle disuse atrophy can cause degenerative changes in neuromuscular junction morphology. Although Daurian ground squirrels (Spermophilus dauricus) are a natural anti-disuse animal model for studying muscle atrophy during hibernation, little is known about the morphological and regulatory mechanisms of their neuromuscular junctions. Here, we found that morphological indices of the soleus muscle were significantly lower during hibernation (torpor and interbout arousal) compared with pre-hibernation but recovered during post-hibernation. In the extensor digitorum longus muscle, neuromuscular junction morphology did not change significantly during hibernation. Agrin-Lrp4-MuSK is a key pathway for the formation and maintenance of the neuromuscular junction. Our results showed that low-density lipoprotein receptor-associated protein 4 (Lrp4) expression in the soleus (slow muscle) decreased by 46.2% in the interbout arousal group compared with the pre-hibernation group (P = 0.019), with recovery in the post-hibernation group. Compared with the pre-hibernation group, agrin expression in the extensor digitorum longus (fast muscle) increased by 67.0% in the interbout arousal group (P = 0.016). In conclusion, periodic up-regulation in agrin expression during interbout arousal may be involved in the maintenance of neuromuscular junction morphology in the extensor digitorum longus muscle during hibernation. The degenerative changes in neuromuscular junction morphology and the periodic decrease in Lrp4 protein expression in the soleus during hibernation, these changes recovered to the pre-hibernation levels in the post-hibernation group, exhibiting significant plasticity. This plasticity may be one of the important mechanisms for resisting disuse atrophy in hibernating animals.NEW & NOTEWORTHY This study is the first to explore the neuromuscular junction morphology of slow- and fast-twitch muscles in Daurian ground squirrels during different periods of hibernation. Results showed that the neuromuscular junction maintained stable morphology in the extensor digitorum longus muscle. The degenerative changes in neuromuscular junction morphology and the periodic decrease in Lrp4 protein expression in the soleus muscle during hibernation recovered in post-hibernation, exhibiting significant plasticity.
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Affiliation(s)
- Yue He
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, People's Republic of China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, People's Republic of China
| | - Hui-Ping Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, People's Republic of China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, People's Republic of China
| | - Fang-Yang Pan
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, People's Republic of China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, People's Republic of China
| | - Shen-Hui Xu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, People's Republic of China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, People's Republic of China
- Department of Digestive Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
- State Key Laboratory of Cancer Biology, Department of Pathology, Xijing Hospital and School of Basic Medicine, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Yun-Fang Gao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, People's Republic of China
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, People's Republic of China
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Kovyazina IV, Khamidullina AA. Muscarinic Cholinoreceptors in Skeletal Muscle: Localization and Functional Role. Acta Naturae 2023; 15:44-55. [PMID: 38234599 PMCID: PMC10790362 DOI: 10.32607/actanaturae.25259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/24/2023] [Indexed: 01/19/2024] Open
Abstract
The review focuses on the modern concepts of the functions of muscarinic cholinoreceptors in skeletal muscles, particularly, in neuromuscular contacts, and that of the signaling pathways associated with the activation of various subtypes of muscarinic receptors in the skeletal muscles of cold-blooded and warm-blooded animals. Despite the long history of research into the involvement of muscarinic receptors in the modulation of neuromuscular transmission, many aspects of such regulation and the associated intracellular mechanisms remain unclear. Now it is obvious that the functions of muscarinic receptors in skeletal muscle are not limited to the autoregulation of neurosecretion from motor nerve endings but also extend to the development and morphological rearrangements of the synaptic apparatus, coordinating them with the degree of activity. The review discusses various approaches to the study of the functions of muscarinic receptors in motor synapses, as well as the problems arising when interpreting experimental data. The final part of the review is devoted to an analysis of some of the intracellular mechanisms and signaling pathways that mediate the effects of muscarinic agents on neuromuscular transmission.
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Affiliation(s)
- I. V. Kovyazina
- Kazan State Medical University, Kazan, 420012 Russian Federation
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, 420111 Russian Federation
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Brija EA, Guan Z, Jetti SK, Littleton JT. Stochastic RNA editing of the Complexin C-terminus within single neurons regulates neurotransmitter release. Cell Rep 2023; 42:113152. [PMID: 37717212 PMCID: PMC10591831 DOI: 10.1016/j.celrep.2023.113152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/22/2023] [Accepted: 08/31/2023] [Indexed: 09/19/2023] Open
Abstract
Neurotransmitter release requires assembly of the SNARE complex fusion machinery, with multiple SNARE-binding proteins regulating when and where synaptic vesicle fusion occurs. The presynaptic protein Complexin (Cpx) controls spontaneous and evoked neurotransmitter release by modulating SNARE complex zippering. Although the central SNARE-binding helix is essential, post-translational modifications to Cpx's C-terminal membrane-binding amphipathic helix regulate its ability to control synaptic vesicle fusion. Here, we demonstrate that RNA editing of the Cpx C-terminus modifies its ability to clamp SNARE-mediated fusion and alters presynaptic output. RNA editing of Cpx across single neurons is stochastic, generating up to eight edit variants that fine tune neurotransmitter release by altering the subcellular localization and clamping properties of the protein. Similar stochastic editing rules for other synaptic genes were observed, indicating editing variability at single adenosines and across multiple mRNAs generates unique synaptic proteomes within the same population of neurons to fine tune presynaptic output.
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Affiliation(s)
- Elizabeth A Brija
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhuo Guan
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Suresh K Jetti
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Ruiz LP, Macpherson PC, Brooks SV. Maintenance of subsynaptic myonuclei number is not driven by neural input. Front Physiol 2023; 14:1266950. [PMID: 37822678 PMCID: PMC10562629 DOI: 10.3389/fphys.2023.1266950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 09/12/2023] [Indexed: 10/13/2023] Open
Abstract
The development and maintenance of neuromuscular junctions (NMJ) are supported by a specialized population of myonuclei that are referred to as the subsynaptic myonuclei (SSM). The relationship between the number of SSM and the integrity of the NMJ as well as the impact of a loss of innervation on SSM remain unclear. This study aimed to clarify these associations by simultaneously analyzing SSM counts and NMJ innervation status in three distinct mouse models of acute and chronic NMJ disruption. SSM were identified using fluorescent immunohistochemistry for Nesprin1 expression, which is highly enriched in SSM, along with anatomical location beneath the muscle fiber motor endplate. Acute denervation, induced by surgical nerve transection, did not affect SSM number after 7 days. Additionally, no significant changes in SSM number were observed during normal aging or in mice with chronic oxidative stress (Sod1 -/-). Both aging WT mice and Sod1 -/- mice accumulated degenerating and denervated NMJ in skeletal muscle, but there was no correlation between innervation status of a given NMJ and SSM number in aged or Sod1 -/- mice. These findings challenge the notion that a loss of SSM is a primary driver of NMJ degradation and leave open questions of the mechanisms that regulate SSM number as well as the physiological significance of the precise SSM number. Further investigations are required to define other properties of the SSM, such as transcriptional profiles and structural integrity, to better understand their role in NMJ maintenance.
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Affiliation(s)
- Lloyd P. Ruiz
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Peter C. Macpherson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Susan V. Brooks
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
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Chen X, Perry S, Wang B, Wang S, Hu J, Loxterkamp E, Dickman D, Han C. Tissue-specific knockout in Drosophila neuromuscular system reveals ESCRT's role in formation of synapse-derived extracellular vesicles. bioRxiv 2023:2023.09.25.559303. [PMID: 37808853 PMCID: PMC10557614 DOI: 10.1101/2023.09.25.559303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Tissue-specific gene knockout by CRISPR/Cas9 is a powerful approach for characterizing gene functions in animal development. However, this approach has been successfully applied in only a small number of Drosophila tissues. The Drosophila motor nervous system is an excellent model system for studying the biology of neuromuscular junction (NMJ). To expand tissue-specific CRISPR to the Drosophila motor system, here we present a CRISPR-mediated tissue-restricted mutagenesis (CRISPR-TRiM) toolkit for knocking out genes in motoneurons, muscles, and glial cells. We validated the efficacy of this toolkit by knocking out known genes in each tissue, demonstrated its orthogonal use with the Gal4/UAS binary expression system, and showed simultaneous knockout of multiple redundant genes. Using these tools, we discovered an essential role for SNARE pathways in NMJ maintenance. Furthermore, we demonstrate that the canonical ESCRT pathway suppresses NMJ bouton growth by downregulating the retrograde Gbb signaling. Lastly, we found that axon termini of motoneurons rely on ESCRT-mediated intra-axonal membrane trafficking to lease extracellular vesicles at the NMJ.
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Affiliation(s)
- Xinchen Chen
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Sarah Perry
- Department of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Bei Wang
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Shuran Wang
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Jiayi Hu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Elizabeth Loxterkamp
- Department of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Chun Han
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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Huang YT, Crick HR, Chaytow H, van der Hoorn D, Alhindi A, Jones RA, Hector RD, Cobb SR, Gillingwater TH. Long-term muscle-specific overexpression of DOK7 in mice using AAV9-tMCK-DOK7. Mol Ther Nucleic Acids 2023; 33:617-628. [PMID: 37637210 PMCID: PMC10457688 DOI: 10.1016/j.omtn.2023.07.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/31/2023] [Indexed: 08/29/2023]
Abstract
Neuromuscular junction (NMJ) dysfunction underlies several diseases, including congenital myasthenic syndromes (CMSs) and motor neuron disease (MND). Molecular pathways governing NMJ stability are therefore of interest from both biological and therapeutic perspectives. Muscle-specific kinase (MuSK) is necessary for the formation and maintenance of post-synaptic elements of the NMJ, and downstream of tyrosine kinases 7 (DOK7) is crucial for activation of the MuSK pathway. Overexpression of DOK7 using AAV9 has been shown to ameliorate neuromuscular pathology in pre-clinical disease models of CMS and MND. However, long-term consequences of DOK7 expression have been sparsely investigated and targeted overexpression of DOK7 in skeletal muscle yet to be established. Here, we developed and characterized a novel AAV9-DOK7 facilitating forced expression of DOK7 under a skeletal muscle-specific promoter. AAV9-tMCK-DOK7 was systemically delivered to newborn mice that were monitored over 6 months. DOK7 overexpression was restricted to skeletal muscles. Body weight, blood biochemistry, and histopathological assessments were unaffected by AAV9-tMCK-DOK7 treatment. In contrast, forced expression of DOK7 resulted in enlargement of both the pre- and post-synaptic components of the NMJ, without causing denervation. We conclude that muscle-specific DOK7 overexpression can be achieved in a safe manner, with the capacity to target NMJs in vivo.
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Affiliation(s)
- Yu-Ting Huang
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
| | - Hannah R. Crick
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
| | - Helena Chaytow
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
| | - Dinja van der Hoorn
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
| | - Abrar Alhindi
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
- Faculty of Medicine, Department of Anatomy, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ross A. Jones
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
| | | | | | - Thomas H. Gillingwater
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Edinburgh EH16 4SB, UK
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Vinciguerra C, Bevilacqua L, Lupica A, Ginanneschi F, Piscosquito G, Rini N, Rossi A, Barone P, Brighina F, Di Stefano V. Diagnosis and Management of Seronegative Myasthenia Gravis: Lights and Shadows. Brain Sci 2023; 13:1286. [PMID: 37759888 PMCID: PMC10526522 DOI: 10.3390/brainsci13091286] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Myasthenia gravis (MG) is an antibody-mediated neuromuscular disease affecting the neuromuscular junction. In most cases, autoantibodies can be detected in the sera of MG patients, thus aiding in diagnosis and allowing for early screening. However, there is a small proportion of patients who have no detectable auto-antibodies, a condition termed "seronegative MG" (SnMG). Several factors contribute to this, including laboratory test inaccuracies, decreased antibody production, immunosuppressive therapy, immunodeficiencies, antigen depletion, and immune-senescence. The diagnosis of SnMG is more challenging and is based on clinical features and neurophysiological tests. The early identification of these patients is needed in order to ensure early treatment and prevent complications. This narrative review aims to examine the latest updates on SnMG, defining the clinical characteristics of affected patients, diagnostic methods, management, and therapeutic scenarios.
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Affiliation(s)
- Claudia Vinciguerra
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Liliana Bevilacqua
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Antonino Lupica
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Federica Ginanneschi
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy; (F.G.)
| | - Giuseppe Piscosquito
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Nicasio Rini
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Alessandro Rossi
- Department of Medical, Surgical and Neurological Sciences, University of Siena, 53100 Siena, Italy; (F.G.)
| | - Paolo Barone
- Neurology Unit, Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84131 Salerno, Italy; (C.V.)
| | - Filippo Brighina
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
| | - Vincenzo Di Stefano
- Neurology Unit, Department of Biomedicine, Neuroscience and Advanced Diagnostics (Bi.N.D.), University of Palermo, 90127 Palermo, Italy (V.D.S.)
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Li Y, Patel M, Baroudi J, Wu M, Gatti S, Liang M, Wipf P, Badawi Y, Meriney SD. A cross-sectional study of ageing at the mouse neuromuscular junction and effects of an experimental therapeutic approach for dynapenia. J Physiol 2023; 601:4135-4150. [PMID: 37606613 DOI: 10.1113/jp284749] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 08/08/2023] [Indexed: 08/23/2023] Open
Abstract
Despite prior efforts to understand and target dynapenia (age-induced loss of muscle strength), this condition remains a major challenge that reduces the quality of life in the aged population. We have focused on the neuromuscular junction (NMJ) where changes in structure and function have rarely been systematically studied as a dynamic and progressive process. Our cross-sectional study found neurotransmission at the male mouse NMJ to be biphasic, displaying an early increase followed by a later decrease, and this phenotype was associated with structural changes to the NMJ. A cross-sectional characterization showed that age-induced alterations fell into four age groups: young adult (3-6 months), adult (7-18 months), early aged (19-24 months), and later aged (25-30 months). We then utilized a small molecule therapeutic candidate, GV-58, applied acutely during the later aged stage to combat age-induced reductions in transmitter release by increasing calcium influx during an action potential, which resulted in a significant increase in transmitter release. This comprehensive study of neuromuscular ageing at the NMJ will enable future research to target critical time points for therapeutic intervention. KEY POINTS: Age-induced frailty and falls are the leading causes of injury-related death and are caused by an age-induced loss of muscle strength due to a combination of neurological and muscular changes. A cross-sectional approach was used to study age-induced changes to the neuromuscular junction in a mouse model, and physiological changes that were biphasic over the ageing time course were found. Changes in physiology at the neuromuscular junction were correlated with alterations in neuromuscular junction morphology. An acutely applied positive allosteric gating modifier of presynaptic voltage-gated calcium channels was tested as a candidate therapeutic strategy that could increase transmitter release at aged neuromuscular junctions. These results provide a detailed time course of age-induced changes at the neuromuscular junction in a mouse model and test a candidate therapeutic strategy for weakness.
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Affiliation(s)
- Y Li
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - M Patel
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - J Baroudi
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - M Wu
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - S Gatti
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - M Liang
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - P Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Y Badawi
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephen D Meriney
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
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Sahota VK, Stone A, Woodling NS, Spiers JG, Steinert JR, Partridge L, Augustin H. Plum modulates Myoglianin and regulates synaptic function in D. melanogaster. Open Biol 2023; 13:230171. [PMID: 37699519 PMCID: PMC10497343 DOI: 10.1098/rsob.230171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
Alterations in the neuromuscular system underlie several neuromuscular diseases and play critical roles in the development of sarcopenia, the age-related loss of muscle mass and function. Mammalian Myostatin (MST) and GDF11, members of the TGF-β superfamily of growth factors, are powerful regulators of muscle size in both model organisms and humans. Myoglianin (MYO), the Drosophila homologue of MST and GDF11, is a strong inhibitor of synaptic function and structure at the neuromuscular junction in flies. Here, we identified Plum, a transmembrane cell surface protein, as a modulator of MYO function in the larval neuromuscular system. Reduction of Plum in the larval body-wall muscles abolishes the previously demonstrated positive effect of attenuated MYO signalling on both muscle size and neuromuscular junction structure and function. In addition, downregulation of Plum on its own results in decreased synaptic strength and body weight, classifying Plum as a (novel) regulator of neuromuscular function and body (muscle) size. These findings offer new insights into possible regulatory mechanisms behind ageing- and disease-related neuromuscular dysfunctions in humans and identify potential targets for therapeutic interventions.
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Affiliation(s)
- Virender K. Sahota
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Aelfwin Stone
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Nathaniel S. Woodling
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Jereme G. Spiers
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Joern R. Steinert
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Linda Partridge
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
| | - Hrvoje Augustin
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
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