1
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Yan J, Bading H. The Disruption of NMDAR/TRPM4 Death Signaling with TwinF Interface Inhibitors: A New Pharmacological Principle for Neuroprotection. Pharmaceuticals (Basel) 2023; 16:1085. [PMID: 37631001 PMCID: PMC10458786 DOI: 10.3390/ph16081085] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 07/24/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
With the discovery that the acquisition of toxic features by extrasynaptic NMDA receptors (NMDARs) involves their physical interaction with the non-selective cation channel, TRPM4, it has become possible to develop a new pharmacological principle for neuroprotection, namely the disruption of the NMDAR/TRPM4 death signaling complex. This can be accomplished through the expression of the TwinF domain, a 57-amino-acid-long stretch of TRPM4 that mediates its interaction with NMDARs, but also using small molecule TwinF interface (TI) inhibitors, also known as NMDAR/TRPM4 interaction interface inhibitors. Both TwinF and small molecule TI inhibitors detoxify extrasynaptic NMDARs without interfering with synaptic NMDARs, which serve important physiological functions in the brain. As the toxic signaling of extrasynaptic NMDARs contributes to a wide range of neurodegenerative conditions, TI inhibitors may offer therapeutic options for currently untreatable human neurodegenerative diseases including Amyotrophic Lateral Sclerosis, Alzheimer's disease, and Huntington's disease.
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Affiliation(s)
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, 69120 Heidelberg, Germany
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2
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Margotta C, Fabbrizio P, Ceccanti M, Cambieri C, Ruffolo G, D'Agostino J, Trolese MC, Cifelli P, Alfano V, Laurini C, Scaricamazza S, Ferri A, Sorarù G, Palma E, Inghilleri M, Bendotti C, Nardo G. Immune-mediated myogenesis and acetylcholine receptor clustering promote a slow disease progression in ALS mouse models. Inflamm Regen 2023; 43:19. [PMID: 36895050 PMCID: PMC9996869 DOI: 10.1186/s41232-023-00270-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/25/2023] [Indexed: 03/11/2023] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a heterogeneous disease in terms of onset and progression rate. This may account for therapeutic clinical trial failure. Transgenic SOD1G93A mice on C57 or 129Sv background have a slow and fast disease progression rate, mimicking the variability observed in patients. Based on evidence inferring the active influence of skeletal muscle on ALS pathogenesis, we explored whether dysregulation in hindlimb skeletal muscle reflects the phenotypic difference between the two mouse models. METHODS Ex vivo immunohistochemical, biochemical, and biomolecular methodologies, together with in vivo electrophysiology and in vitro approaches on primary cells, were used to afford a comparative and longitudinal analysis of gastrocnemius medialis between fast- and slow-progressing ALS mice. RESULTS We reported that slow-progressing mice counteracted muscle denervation atrophy by increasing acetylcholine receptor clustering, enhancing evoked currents, and preserving compound muscle action potential. This matched with prompt and sustained myogenesis, likely triggered by an early inflammatory response switching the infiltrated macrophages towards a M2 pro-regenerative phenotype. Conversely, upon denervation, fast-progressing mice failed to promptly activate a compensatory muscle response, exhibiting a rapidly progressive deterioration of muscle force. CONCLUSIONS Our findings further pinpoint the pivotal role of skeletal muscle in ALS, providing new insights into underestimated disease mechanisms occurring at the periphery and providing useful (diagnostic, prognostic, and mechanistic) information to facilitate the translation of cost-effective therapeutic strategies from the laboratory to the clinic.
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Affiliation(s)
- Cassandra Margotta
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Paola Fabbrizio
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Marco Ceccanti
- Department of Human Neurosciences, Rare Neuromuscular Diseases Centre, Sapienza University of Rome, 00185, Rome, Italy
| | - Chiara Cambieri
- Department of Human Neurosciences, Rare Neuromuscular Diseases Centre, Sapienza University of Rome, 00185, Rome, Italy
| | - Gabriele Ruffolo
- Laboratory Affiliated to Istituto Pasteur Italia, Department of Physiology and Pharmacology, Sapienza University of Rome, 00185, Rome, Italy.,IRCCS San Raffaele Roma, 00163, Rome, Italy
| | - Jessica D'Agostino
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Maria Chiara Trolese
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Pierangelo Cifelli
- Department of Applied Clinical and Biotechnological Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | | | - Christian Laurini
- Department of Human Neurosciences, Rare Neuromuscular Diseases Centre, Sapienza University of Rome, 00185, Rome, Italy
| | | | - Alberto Ferri
- IRCCS Fondazione Santa Lucia, Rome, Italy.,Institute of Translational Pharmacology (IFT-CNR), Rome, Italy
| | - Gianni Sorarù
- Department of Neuroscience, Azienda Ospedaliera di Padova, Via Giustiniani 2, 35128, Padua, Italy
| | - Eleonora Palma
- Laboratory Affiliated to Istituto Pasteur Italia, Department of Physiology and Pharmacology, Sapienza University of Rome, 00185, Rome, Italy.,IRCCS San Raffaele Roma, 00163, Rome, Italy
| | - Maurizio Inghilleri
- Department of Human Neurosciences, Rare Neuromuscular Diseases Centre, Sapienza University of Rome, 00185, Rome, Italy
| | - Caterina Bendotti
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy.
| | - Giovanni Nardo
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
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3
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Ivorra I, Alberola-Die A, Cobo R, González-Ros JM, Morales A. Xenopus Oocytes as a Powerful Cellular Model to Study Foreign Fully-Processed Membrane Proteins. MEMBRANES 2022; 12:986. [PMID: 36295745 PMCID: PMC9610954 DOI: 10.3390/membranes12100986] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/05/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
The use of Xenopus oocytes in electrophysiological and biophysical research constitutes a long and successful story, providing major advances to the knowledge of the function and modulation of membrane proteins, mostly receptors, ion channels, and transporters. Earlier reports showed that these cells are capable of correctly expressing heterologous proteins after injecting the corresponding mRNA or cDNA. More recently, the Xenopus oocyte has become an outstanding host-cell model to carry out detailed studies on the function of fully-processed foreign membrane proteins after their microtransplantation to the oocyte. This review focused on the latter overall process of transplanting foreign membrane proteins to the oocyte after injecting plasma membranes or purified and reconstituted proteins. This experimental approach allows for the study of both the function of mature proteins, with their native stoichiometry and post-translational modifications, and their putative modulation by surrounding lipids, mostly when the protein is purified and reconstituted in lipid matrices of defined composition. Remarkably, this methodology enables functional microtransplantation to the oocyte of membrane receptors, ion channels, and transporters from different sources including human post-mortem tissue banks. Despite the large progress achieved over the last decades on the structure, function, and modulation of neuroreceptors and ion channels in healthy and pathological tissues, many unanswered questions remain and, most likely, Xenopus oocytes will continue to help provide valuable responses.
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Affiliation(s)
- Isabel Ivorra
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Apdo 99, E-03080 Alicante, Spain
| | - Armando Alberola-Die
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Apdo 99, E-03080 Alicante, Spain
| | - Raúl Cobo
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Apdo 99, E-03080 Alicante, Spain
| | - José Manuel González-Ros
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, E-03202 Elche, Spain
| | - Andrés Morales
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Apdo 99, E-03080 Alicante, Spain
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4
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Ceccanti M, Libonati L, Ruffolo G, Cifelli P, Moret F, Frasca V, Palma E, Inghilleri M, Cambieri C. Effects of 3,4-diaminopyridine on myasthenia gravis: Preliminary results of an open-label study. Front Pharmacol 2022; 13:982434. [PMID: 36052140 PMCID: PMC9424766 DOI: 10.3389/fphar.2022.982434] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Background: 3,4-diaminopyridine (3,4-DAP) can lead to clinical and electrophysiological improvement in myasthenic syndrome; it may thus represent a valuable therapeutic option for patients intolerant to pyridostigmine. Objective: to assess 3,4-diaminopyridine (3,4-DAP) effects and tolerability in patients with anti-AChR myasthenia gravis. Method: Effects were monitored electrophysiologically by repetitive nerve stimulation (RNS) and by standardized clinical testing (QMG score) before and after a single dose administration of 3,4-DAP 10 mg per os in 15 patients. Patients were divided according to their Myasthenia Gravis Foundation of America (MGFA) class into mild and severe. Results: No significant side effects were found, apart from transient paresthesia. 3,4-DAP had a significant effect on the QMG score (p = 0.0251), on repetitive nerve stimulation (p = 0.0251), and on the forced vital capacity (p = 0.03), thus indicating that it may reduce the level of disability and the decremental muscle response. When the patients were divided according to the MGFA classification, 3,4-DAP showed a positive effect in the severe group, either for the QMG score (p = 0.031) or for the RNS decrement (p = 0.031). No significant difference was observed in any of the outcome measures within the mild group (p > 0.05). A direct effect of 3,4-DAP on nicotinic ACh receptors (nAChRs) was excluded since human nAChRs reconstituted in an expression system, which were not affected by 3,4-DAP application. Conclusion: Our results suggest that 3,4-DAP may be a useful add-on therapy, especially in most severe patients or when immunosuppressive treatment has not yet reached its full effect or when significant side-effects are associated with anticholinesterase.
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Affiliation(s)
- Marco Ceccanti
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
| | - Laura Libonati
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Institute Pasteur- Fondazione Cenci Bolognetti, University of Rome Sapienza, Rome, Italy
- IRCCS San Raffaele Pisana, Rome, Italy
| | - Pierangelo Cifelli
- Department of Applied Clinical and Biotechnological Sciences, University of L'Aquila, L'Aquila, Italy
| | - Federica Moret
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
| | - Vittorio Frasca
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Institute Pasteur- Fondazione Cenci Bolognetti, University of Rome Sapienza, Rome, Italy
| | - Maurizio Inghilleri
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
| | - Chiara Cambieri
- Neuromuscular Disorders Unit, Department of Human Neurosciences, Sapienza University, Rome, Italy
- *Correspondence: Chiara Cambieri,
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5
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Cifelli P, Ruffolo G, Ceccanti M, Cambieri C, Libonati L, Palma E, Inghilleri M. Classical and Unexpected Effects of Ultra-Micronized PEA in Neuromuscular Function. Biomolecules 2022; 12:biom12060758. [PMID: 35740883 PMCID: PMC9221058 DOI: 10.3390/biom12060758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 05/23/2022] [Accepted: 05/27/2022] [Indexed: 02/06/2023] Open
Abstract
Recently, the endocannabinoid system has attracted growing attention from the scientific community for its involvement in homeostatic and pathological processes as they pertains to human physiology. Among the constituents of the endocannabinoid system, the molecule palmitoyl ethanolamide has particularly been studied for its ability to reduce several inflammatory processes involving the central nervous system. Here, we reviewed published literature and summarized the main targets of the palmitoyl ethanolamide, along with its unique possible mechanisms for restoring correct functioning of the central nervous system. Moreover, we have highlighted a less-known characteristic of palmitoyl ethanolamide, namely its ability to modulate the function of the neuromuscular junction by binding to acetylcholine receptors in different experimental conditions. Indeed, there are several studies that have highlighted how ultra-micronized palmitoyl ethanolamide is an interesting nutraceutical support for the treatment of pathological neuromuscular conditions, specifically when the normal activity of the acetylcholine receptor is altered. Although further multicentric clinical trials are needed to confirm the efficacy of ultra-micronized palmitoyl ethanolamide in improving symptoms of neuromuscular diseases, all the literature reviewed here strongly supports the ability of this endocannabinoid-like molecule to modulate the acetylcholine receptors thus resulting as a valid support for the treatment of human neuromuscular diseases.
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Affiliation(s)
- Pierangelo Cifelli
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy
- Correspondence: (P.C.); (M.I.)
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (G.R.); (E.P.)
- IRCCS San Raffaele Roma, 00163 Rome, Italy
| | - Marco Ceccanti
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy; (M.C.); (C.C.); (L.L.)
| | - Chiara Cambieri
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy; (M.C.); (C.C.); (L.L.)
| | - Laura Libonati
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy; (M.C.); (C.C.); (L.L.)
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (G.R.); (E.P.)
| | - Maurizio Inghilleri
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy; (M.C.); (C.C.); (L.L.)
- Correspondence: (P.C.); (M.I.)
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6
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Verma S, Khurana S, Vats A, Sahu B, Ganguly NK, Chakraborti P, Gourie-Devi M, Taneja V. Neuromuscular Junction Dysfunction in Amyotrophic Lateral Sclerosis. Mol Neurobiol 2022; 59:1502-1527. [PMID: 34997540 DOI: 10.1007/s12035-021-02658-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/18/2021] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive degeneration of motor neurons leading to skeletal muscle denervation. Earlier studies have shown that motor neuron degeneration begins in motor cortex and descends to the neuromuscular junction (NMJ) in a dying forward fashion. However, accumulating evidences support that ALS is a distal axonopathy where early pathological changes occur at the NMJ, prior to onset of clinical symptoms and propagates towards the motor neuron cell body supporting "dying back" hypothesis. Despite several evidences, series of events triggering NMJ disassembly in ALS are still obscure. Neuromuscular junction is a specialized tripartite chemical synapse which involves a well-coordinated communication among the presynaptic motor neuron, postsynaptic skeletal muscle, and terminal Schwann cells. This review provides comprehensive insight into the role of NMJ in ALS pathogenesis. We have emphasized the molecular alterations in cellular components of NMJ leading to loss of effective neuromuscular transmission in ALS. Further, we provide a preview into research involved in exploring NMJ as potential target for designing effective therapies for ALS.
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Affiliation(s)
- Sagar Verma
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.,Department of Biotechnology, Jamia Hamdard, Delhi, India
| | - Shiffali Khurana
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.,Department of Biomedical Science, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, India
| | - Abhishek Vats
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bandana Sahu
- Department of Research, Sir Ganga Ram Hospital, Delhi, India
| | | | | | | | - Vibha Taneja
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.
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7
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Luttrell SM, Smith AST, Mack DL. Creating stem cell-derived neuromuscular junctions in vitro. Muscle Nerve 2021; 64:388-403. [PMID: 34328673 PMCID: PMC9292444 DOI: 10.1002/mus.27360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/28/2021] [Accepted: 06/21/2021] [Indexed: 12/14/2022]
Abstract
Recent development of novel therapies has improved mobility and quality of life for people suffering from inheritable neuromuscular disorders. Despite this progress, the majority of neuromuscular disorders are still incurable, in part due to a lack of predictive models of neuromuscular junction (NMJ) breakdown. Improvement of predictive models of a human NMJ would be transformative in terms of expanding our understanding of the mechanisms that underpin development, maintenance, and disease, and as a testbed with which to evaluate novel therapeutics. Induced pluripotent stem cells (iPSCs) are emerging as a clinically relevant and non‐invasive cell source to create human NMJs to study synaptic development and maturation, as well as disease modeling and drug discovery. This review will highlight the recent advances and remaining challenges to generating an NMJ capable of eliciting contraction of stem cell‐derived skeletal muscle in vitro. We explore the advantages and shortcomings of traditional NMJ culturing platforms, as well as the pioneering technologies and novel, biomimetic culturing systems currently in use to guide development and maturation of the neuromuscular synapse and extracellular microenvironment. Then, we will explore how this NMJ‐in‐a‐dish can be used to study normal assembly and function of the efferent portion of the neuromuscular arc, and how neuromuscular disease‐causing mutations disrupt structure, signaling, and function.
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Affiliation(s)
- Shawn M Luttrell
- Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA
| | - Alec S T Smith
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - David L Mack
- Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
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8
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Xia J, Yang H, Mu M, Micovic N, Poskanzer KE, Monaghan JR, Clark HA. Imaging in vivo acetylcholine release in the peripheral nervous system with a fluorescent nanosensor. Proc Natl Acad Sci U S A 2021; 118:e2023807118. [PMID: 33795516 PMCID: PMC8040656 DOI: 10.1073/pnas.2023807118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The ability to monitor the release of neurotransmitters during synaptic transmission would significantly impact the diagnosis and treatment of neurological diseases. Here, we present a DNA-based enzymatic nanosensor for quantitative detection of acetylcholine (ACh) in the peripheral nervous system of living mice. ACh nanosensors consist of DNA as a scaffold, acetylcholinesterase as a recognition component, pH-sensitive fluorophores as signal generators, and α-bungarotoxin as a targeting moiety. We demonstrate the utility of the nanosensors in the submandibular ganglia of living mice to sensitively detect ACh ranging from 0.228 to 358 μM. In addition, the sensor response upon electrical stimulation of the efferent nerve is dose dependent, reversible, and we observe a reduction of ∼76% in sensor signal upon pharmacological inhibition of ACh release. Equipped with an advanced imaging processing tool, we further spatially resolve ACh signal propagation on the tissue level. Our platform enables sensitive measurement and mapping of ACh transmission in the peripheral nervous system.
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Affiliation(s)
- Junfei Xia
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Hongrong Yang
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Michelle Mu
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Nicholas Micovic
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115
| | - Kira E Poskanzer
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143
- Kavli Insititute for Fundamental Neuroscience, San Francisco, CA 94143
| | - James R Monaghan
- Department of Biology, College of Science, Northeastern University, Boston, MA 02115
| | - Heather A Clark
- Department of Bioengineering, College of Engineering, Northeastern University, Boston, MA 02115;
- Department of Chemistry and Chemical Biology, College of Science, Northeastern University, Boston, MA 02115
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9
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Abstract
Background: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of upper and lower motor neurons with high burden on society. Despite tremendous efforts over the last several decades, there is still no definite cure for ALS. Up to now, only two disease-modifying agents, riluzole and edaravone, are approved by U.S. Food and Drug Administration (FDA) for ALS treatment, which only modestly improves survival and disease progression. Major challenging issues to find an effective therapy are heterogeneity in the pathogenesis and genetic variability of ALS. As such, stem cell therapy has been recently a focus of both preclinical and clinical investigations of ALS. This is because stem cells have multifaceted features that can potentially target multiple pathogenic mechanisms in ALS even though its underlying mechanisms are not completely elucidated. Methods & Results: Here, we will have an overview of stem cell therapy in ALS, including their therapeutic mechanisms, the results of recent clinical trials as well as ongoing clinical trials. In addition, we will further discuss complications and limitations of stem cell therapy in ALS. Conclusion: The determination of whether stem cells offer a viable treatment strategy for ALS rests on well-designed and appropriately powered future clinical trials. Randomized, double-blinded, and sham-controlled studies would be valuable.
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Affiliation(s)
- Goun Je
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA USA
| | - Kiandokht Keyhanian
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA USA
| | - Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA USA
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10
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de Jongh R, Spijkers XM, Pasteuning-Vuhman S, Vulto P, Pasterkamp RJ. Neuromuscular junction-on-a-chip: ALS disease modeling and read-out development in microfluidic devices. J Neurochem 2021; 157:393-412. [PMID: 33382092 DOI: 10.1111/jnc.15289] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/24/2020] [Accepted: 12/28/2020] [Indexed: 12/21/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal and progressive neurodegenerative disease affecting upper and lower motor neurons with no cure available. Clinical and animal studies reveal that the neuromuscular junction (NMJ), a synaptic connection between motor neurons and skeletal muscle fibers, is highly vulnerable in ALS and suggest that NMJ defects may occur at the early stages of the disease. However, mechanistic insight into how NMJ dysfunction relates to the onset and progression of ALS is incomplete, which hampers therapy development. This is, in part, caused by a lack of robust in vitro models. The ability to combine microfluidic and induced pluripotent stem cell (iPSC) technologies has opened up new avenues for studying molecular and cellular ALS phenotypes in vitro. Microfluidic devices offer several advantages over traditional culture approaches when modeling the NMJ, such as the spatial separation of different cell types and increased control over the cellular microenvironment. Moreover, they are compatible with 3D cell culture, which enhances NMJ functionality and maturity. Here, we review how microfluidic technology is currently being employed to develop more reliable in vitro NMJ models. To validate and phenotype such models, various morphological and functional read-outs have been developed. We describe and discuss the relevance of these read-outs and specifically illustrate how these read-outs have enhanced our understanding of NMJ pathology in ALS. Finally, we share our view on potential future directions and challenges.
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Affiliation(s)
- Rianne de Jongh
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Xandor M Spijkers
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands.,Mimetas B.V., Organ-on-a-chip Company, Leiden, The Netherlands
| | - Svetlana Pasteuning-Vuhman
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
| | - Paul Vulto
- Mimetas B.V., Organ-on-a-chip Company, Leiden, The Netherlands
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands
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11
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A Low Cost Antibody Signal Enhancer Improves Immunolabeling in Cell Culture, Primate Brain and Human Cancer Biopsy. Neuroscience 2020; 439:275-286. [DOI: 10.1016/j.neuroscience.2020.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 01/02/2020] [Accepted: 01/06/2020] [Indexed: 12/14/2022]
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12
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Goel P, Nishimura S, Chetlapalli K, Li X, Chen C, Dickman D. Distinct Target-Specific Mechanisms Homeostatically Stabilize Transmission at Pre- and Post-synaptic Compartments. Front Cell Neurosci 2020; 14:196. [PMID: 32676010 PMCID: PMC7333441 DOI: 10.3389/fncel.2020.00196] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/05/2020] [Indexed: 12/28/2022] Open
Abstract
Neurons must establish and stabilize connections made with diverse targets, each with distinct demands and functional characteristics. At Drosophila neuromuscular junctions (NMJs), synaptic strength remains stable in a manipulation that simultaneously induces hypo-innervation on one target and hyper-innervation on the other. However, the expression mechanisms that achieve this exquisite target-specific homeostatic control remain enigmatic. Here, we identify the distinct target-specific homeostatic expression mechanisms. On the hypo-innervated target, an increase in postsynaptic glutamate receptor (GluR) abundance is sufficient to compensate for reduced innervation, without any apparent presynaptic adaptations. In contrast, a target-specific reduction in presynaptic neurotransmitter release probability is reflected by a decrease in active zone components restricted to terminals of hyper-innervated targets. Finally, loss of postsynaptic GluRs on one target induces a compartmentalized, homeostatic enhancement of presynaptic neurotransmitter release called presynaptic homeostatic potentiation (PHP) that can be precisely balanced with the adaptations required for both hypo- and hyper-innervation to maintain stable synaptic strength. Thus, distinct anterograde and retrograde signaling systems operate at pre- and post-synaptic compartments to enable target-specific, homeostatic control of neurotransmission.
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13
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Ceccanti M, Pozzilli V, Cambieri C, Libonati L, Onesti E, Frasca V, Fiorini I, Petrucci A, Garibaldi M, Palma E, Bendotti C, Fabbrizio P, Trolese MC, Nardo G, Inghilleri M. Creatine Kinase and Progression Rate in Amyotrophic Lateral Sclerosis. Cells 2020; 9:cells9051174. [PMID: 32397320 PMCID: PMC7291088 DOI: 10.3390/cells9051174] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/29/2020] [Accepted: 05/06/2020] [Indexed: 11/16/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with no recognized clinical prognostic factor. Creatinine kinase (CK) increase in these patients is already described with conflicting results on prognosis and survival. In 126 ALS patients who were fast or slow disease progressors, CK levels were assayed for 16 months every 4 months in an observational case-control cohort study with prospective data collection conducted in Italy. CK was also measured at baseline in 88 CIDP patients with secondary axonal damage and in two mouse strains (129SvHSD and C57-BL) carrying the same SOD1G93A transgene expression but showing a fast (129Sv-SOD1G93A) and slow (C57-SOD1G93A) ALS progression rate. Higher CK was found in ALS slow progressors compared to fast progressors in T1, T2, T3, and T4, with a correlation with Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) scores. Higher CK was found in spinal compared to bulbar-onset patients. Transgenic and non-transgenic C57BL mice showed higher CK levels compared to 129SvHSD strain. At baseline mean CK was higher in ALS compared to CIDP. CK can predict the disease progression, with slow progressors associated with higher levels and fast progressors to lower levels, in both ALS patients and mice. CK is higher in ALS patients compared to patients with CIDP with secondary axonal damage; the higher levels of CK in slow progressors patients, but also in C57BL transgenic and non-transgenic mice designs CK as a predisposing factor for disease rate progression.
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Affiliation(s)
- Marco Ceccanti
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Valeria Pozzilli
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Chiara Cambieri
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Laura Libonati
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Emanuela Onesti
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Vittorio Frasca
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Ilenia Fiorini
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
| | - Antonio Petrucci
- Centre for Neuromuscular and Neurological Rare Diseases, San Camillo Forlanini Hospital, 00152 Rome, Italy;
| | - Matteo Garibaldi
- Neuromuscular Disease Centre, Department of Neurology, Mental Health and Sensory Organs (NESMOS), Sant’Andrea Hospital, Sapienza University of Rome, 00189 Rome, Italy;
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Laboratory Affiliated to Istituto Pasteur Italia, Sapienza University of Rome, 00185 Rome, Italy;
| | - Caterina Bendotti
- Laboratory Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Famacologiche Mario Negri-IRCCS, 20156 Milan, Italy; (C.B.); (P.F.); (M.C.T.); (G.N.)
| | - Paola Fabbrizio
- Laboratory Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Famacologiche Mario Negri-IRCCS, 20156 Milan, Italy; (C.B.); (P.F.); (M.C.T.); (G.N.)
| | - Maria Chiara Trolese
- Laboratory Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Famacologiche Mario Negri-IRCCS, 20156 Milan, Italy; (C.B.); (P.F.); (M.C.T.); (G.N.)
| | - Giovanni Nardo
- Laboratory Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Famacologiche Mario Negri-IRCCS, 20156 Milan, Italy; (C.B.); (P.F.); (M.C.T.); (G.N.)
| | - Maurizio Inghilleri
- Rare Neuromuscular Diseases Centre, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy; (M.C.); (V.P.); (C.C.); (L.L.); (E.O.); (V.F.); (I.F.)
- Correspondence: ; Tel.: +39-0-6499-14122
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Bourefis AR, Campanari ML, Buee-Scherrer V, Kabashi E. Functional characterization of a FUS mutant zebrafish line as a novel genetic model for ALS. Neurobiol Dis 2020; 142:104935. [PMID: 32380281 DOI: 10.1016/j.nbd.2020.104935] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/22/2020] [Accepted: 04/29/2020] [Indexed: 12/12/2022] Open
Abstract
Mutations in Fused in sarcoma (FUS), an RNA-binding protein, are known to cause Amyotrophic Lateral Sclerosis (ALS). However, molecular mechanisms due to loss of FUS function remain unclear and controversial. Here, we report the characterization and phenotypic analysis of a deletion mutant of the unique FUS orthologue in zebrafish where Fus protein levels are depleted. The homozygous mutants displayed a reduced lifespan as well as impaired motor abilities associated with specific cellular deficits, including decreased motor neurons length and neuromuscular junctions (NMJ) fragmentation. Furthermore, we demonstrate that these cellular impairments are linked to the misregulation of mRNA expression of acetylcholine receptor (AChR) subunits and histone deacetylase 4, markers of denervation and reinnervation processes observed in ALS patients. In addition, fus loss of function alters tau transcripts favoring the expression of small tau isoforms. Overall, this new animal model extends our knowledge on FUS and supports the relevance of FUS loss of function in ALS physiopathology.
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Affiliation(s)
- Annis-Rayan Bourefis
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France; Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, INSERM Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM), 75013 Paris, France
| | - Maria-Letizia Campanari
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France; Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, INSERM Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM), 75013 Paris, France
| | | | - Edor Kabashi
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France; Sorbonne Université, Université Pierre et Marie Curie (UPMC), Université de Paris 06, INSERM Unité 1127, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7225 Institut du Cerveau et de la Moelle Épinière (ICM), 75013 Paris, France.
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15
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Zeng SL, Sudlow LC, Berezin MY. Using Xenopus oocytes in neurological disease drug discovery. Expert Opin Drug Discov 2019; 15:39-52. [PMID: 31674217 DOI: 10.1080/17460441.2020.1682993] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Introduction: Neurological diseases present a difficult challenge in drug discovery. Many of the current treatments have limited efficiency or result in a variety of debilitating side effects. The search of new therapies is of a paramount importance, since the number of patients that require a better treatment is growing rapidly. As an in vitro model, Xenopus oocytes provide the drug developer with many distinct advantages, including size, durability, and efficiency in exogenous protein expression. However, there is an increasing need to refine the recent breakthroughs.Areas covered: This review covers the usage and recent advancements of Xenopus oocytes for drug discovery in neurological diseases from expression and functional measurement techniques to current applications in Alzheimer's disease, painful neuropathies, and amyotrophic lateral sclerosis (ALS). The existing limitations of Xenopus oocytes in drug discovery are also discussed.Expert opinion: With the rise of aging population and neurological disorders, Xenopus oocytes, will continue to play an important role in understanding the mechanism of the disease, identification and validation of novel molecular targets, and drug screening, providing high-quality data despite the technical limitations. With further advances in oocytes-related techniques toward an accurate modeling of the disease, the diagnostics and treatment of neuropathologies will be becoming increasing personalized.
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Affiliation(s)
- Steven L Zeng
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Leland C Sudlow
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Mikhail Y Berezin
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
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16
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Genin EC, Madji Hounoum B, Bannwarth S, Fragaki K, Lacas-Gervais S, Mauri-Crouzet A, Lespinasse F, Neveu J, Ropert B, Augé G, Cochaud C, Lefebvre-Omar C, Bigou S, Chiot A, Mochel F, Boillée S, Lobsiger CS, Bohl D, Ricci JE, Paquis-Flucklinger V. Mitochondrial defect in muscle precedes neuromuscular junction degeneration and motor neuron death in CHCHD10 S59L/+ mouse. Acta Neuropathol 2019; 138:123-145. [PMID: 30874923 DOI: 10.1007/s00401-019-01988-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/21/2019] [Accepted: 03/08/2019] [Indexed: 12/30/2022]
Abstract
Recently, we provided genetic basis showing that mitochondrial dysfunction can trigger motor neuron degeneration, through identification of CHCHD10 encoding a mitochondrial protein. We reported patients, carrying the p.Ser59Leu heterozygous mutation in CHCHD10, from a large family with a mitochondrial myopathy associated with motor neuron disease (MND). Rapidly, our group and others reported CHCHD10 mutations in amyotrophic lateral sclerosis (ALS), frontotemporal dementia-ALS and other neurodegenerative diseases. Here, we generated knock-in (KI) mice, carrying the p.Ser59Leu mutation, that mimic the mitochondrial myopathy with mtDNA instability displayed by the patients from our original family. Before 14 months of age, all KI mice developed a fatal mitochondrial cardiomyopathy associated with enhanced mitophagy. CHCHD10S59L/+ mice also displayed neuromuscular junction (NMJ) and motor neuron degeneration with hyper-fragmentation of the motor end plate and moderate but significant motor neuron loss in lumbar spinal cord at the end stage of the disease. At this stage, we observed TDP-43 cytoplasmic aggregates in spinal neurons. We also showed that motor neurons differentiated from human iPSC carrying the p.Ser59Leu mutation were much more sensitive to Staurosporine or glutamate-induced caspase activation than control cells. These data confirm that mitochondrial deficiency associated with CHCHD10 mutations can be at the origin of MND. CHCHD10 is highly expressed in the NMJ post-synaptic part. Importantly, the fragmentation of the motor end plate was associated with abnormal CHCHD10 expression that was also observed closed to NMJs which were morphologically normal. Furthermore, we found OXPHOS deficiency in muscle of CHCHD10S59L/+ mice at 3 months of age in the absence of neuron loss in spinal cord. Our data show that the pathological effects of the p.Ser59Leu mutation target muscle prior to NMJ and motor neurons. They likely lead to OXPHOS deficiency, loss of cristae junctions and destabilization of internal membrane structure within mitochondria at motor end plate of NMJ, impairing neurotransmission. These data are in favor with a key role for muscle in MND associated with CHCHD10 mutations.
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17
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A Screen for Synaptic Growth Mutants Reveals Mechanisms That Stabilize Synaptic Strength. J Neurosci 2019; 39:4051-4065. [PMID: 30902873 DOI: 10.1523/jneurosci.2601-18.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 01/28/2023] Open
Abstract
Synapses grow, prune, and remodel throughout development, experience, and disease. This structural plasticity can destabilize information transfer in the nervous system. However, neural activity remains stable throughout life, implying that adaptive countermeasures exist that maintain neurotransmission within proper physiological ranges. Aberrant synaptic structure and function have been associated with a variety of neural diseases, including Fragile X syndrome, autism, and intellectual disability. We have screened 300 mutants in Drosophila larvae of both sexes for defects in synaptic growth at the neuromuscular junction, identifying 12 mutants with severe reductions or enhancements in synaptic growth. Remarkably, electrophysiological recordings revealed that synaptic strength was unchanged in all but one of these mutants compared with WT. We used a combination of genetic, anatomical, and electrophysiological analyses to illuminate three mechanisms that stabilize synaptic strength despite major disparities in synaptic growth. These include compensatory changes in (1) postsynaptic neurotransmitter receptor abundance, (2) presynaptic morphology, and (3) active zone structure. Together, this characterization identifies new mutants with defects in synaptic growth and the adaptive strategies used by synapses to homeostatically stabilize neurotransmission in response.SIGNIFICANCE STATEMENT This study reveals compensatory mechanisms used by synapses to ensure stable functionality during severe alterations in synaptic growth using the neuromuscular junction of Drosophila melanogaster as a model system. Through a forward genetic screen, we identify mutants that exhibit dramatic undergrown or overgrown synapses yet express stable levels of synaptic strength, with three specific compensatory mechanisms discovered. Thus, this study reveals novel insights into the adaptive strategies that constrain neurotransmission within narrow physiological ranges while allowing considerable flexibility in overall synapse number. More broadly, these findings provide insights into how stable synaptic function may be maintained in the nervous system during periods of intensive synaptic growth, pruning, and remodeling.
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18
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Neuromuscular magnetic stimulation counteracts muscle decline in ALS patients: results of a randomized, double-blind, controlled study. Sci Rep 2019; 9:2837. [PMID: 30808899 PMCID: PMC6391419 DOI: 10.1038/s41598-019-39313-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 01/21/2019] [Indexed: 12/14/2022] Open
Abstract
The aim of the study was to verify whether neuromuscular magnetic stimulation (NMMS) improves muscle function in spinal-onset amyotrophic lateral sclerosis (ALS) patients. Twenty-two ALS patients were randomized in two groups to receive, daily for two weeks, NMMS in right or left arm (referred to as real-NMMS, rNMMS), and sham NMMS (sNMMS) in the opposite arm. All the patients underwent a median nerve conduction (compound muscle action potential, CMAP) study and a clinical examination that included a handgrip strength test and an evaluation of upper limb muscle strength by means of the Medical Research Council Muscle Scale (MRC). Muscle biopsy was then performed bilaterally on the flexor carpi radialis muscle to monitor morpho-functional parameters and molecular changes. Patients and physicians who performed examinations were blinded to the side of real intervention. The primary outcome was the change in the muscle strength in upper arms. The secondary outcomes were the change from baseline in the CMAP amplitudes, in the nicotinic ACh currents, in the expression levels of a selected panel of genes involved in muscle growth and atrophy, and in histomorphometric parameters of ALS muscle fibers. The Repeated Measures (RM) ANOVA with a Greenhouse-Geisser correction (sphericity not assumed) showed a significant effect [F(3, 63) = 5.907, p < 0.01] of rNMMS on MRC scale at the flexor carpi radialis muscle, thus demonstrating that the rNMMS significantly improves muscle strength in flexor muscles in the forearm. Secondary outcomes showed that the improvement observed in rNMMS-treated muscles was associated to counteracting muscle atrophy, down-modulating the proteolysis, and increasing the efficacy of nicotinic ACh receptors (AChRs). We did not observe any significant difference in pre- and post-stimulation CMAP amplitudes, evoked by median nerve stimulation. This suggests that the improvement in muscle strength observed in the stimulated arm is unlikely related to reinnervation. The real and sham treatments were well tolerated without evident side effects. Although promising, this is a proof of concept study, without an immediate clinical translation, that requires further clinical validation.
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19
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Cappello V, Francolini M. Neuromuscular Junction Dismantling in Amyotrophic Lateral Sclerosis. Int J Mol Sci 2017; 18:ijms18102092. [PMID: 28972545 PMCID: PMC5666774 DOI: 10.3390/ijms18102092] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/25/2017] [Accepted: 09/28/2017] [Indexed: 12/13/2022] Open
Abstract
Neuromuscular junction assembly and plasticity during embryonic, postnatal, and adult life are tightly regulated by the continuous cross-talk among motor nerve endings, muscle fibers, and glial cells. Altered communications among these components is thought to be responsible for the physiological age-related changes at this synapse and possibly for its destruction in pathological states. Neuromuscular junction dismantling plays a crucial role in the onset of Amyotrophic Lateral Sclerosis (ALS). ALS is characterized by the degeneration and death of motor neurons leading to skeletal muscle denervation, atrophy and, most often, death of the patient within five years from diagnosis. ALS is a non-cell autonomous disease as, besides motor neuron degeneration, glial cells, and possibly muscle fibers, play a role in its onset and progression. Here, we will review the recent literature regarding the mechanisms leading to neuromuscular junction disassembly and muscle denervation focusing on the role of the three players of this peripheral tripartite synapse.
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Affiliation(s)
- Valentina Cappello
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia Piazza San Silvestro 12, 56127 Pisa, Italy.
| | - Maura Francolini
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano-Via Vanvitelli 32, 20129 Milano, Italy.
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20
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Loeffler JP, Picchiarelli G, Dupuis L, Gonzalez De Aguilar JL. The Role of Skeletal Muscle in Amyotrophic Lateral Sclerosis. Brain Pathol 2016; 26:227-36. [PMID: 26780251 PMCID: PMC8029271 DOI: 10.1111/bpa.12350] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 01/14/2016] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal adult‐onset disease primarily characterized by upper and lower motor neuron degeneration, muscle wasting and paralysis. It is increasingly accepted that the pathological process leading to ALS is the result of multiple disease mechanisms that operate within motor neurons and other cell types both inside and outside the central nervous system. The implication of skeletal muscle has been the subject of a number of studies conducted on patients and related animal models. In this review, we describe the features of ALS muscle pathology and discuss on the contribution of muscle to the pathological process. We also give an overview of the therapeutic strategies proposed to alleviate muscle pathology or to deliver curative agents to motor neurons. ALS muscle mainly suffers from oxidative stress, mitochondrial dysfunction and bioenergetic disturbances. However, the way by which the disease affects different types of myofibers depends on their contractile and metabolic features. Although the implication of muscle in nourishing the degenerative process is still debated, there is compelling evidence suggesting that it may play a critical role. Detailed understanding of the muscle pathology in ALS could, therefore, lead to the identification of new therapeutic targets.
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Affiliation(s)
- Jean-Philippe Loeffler
- Université de Strasbourg, UMR_S 1118, Strasbourg, France.,INSERM, U1118, Mécanismes Centraux et Péripheriques de la Neurodégénérescence, Strasbourg, France
| | - Gina Picchiarelli
- Université de Strasbourg, UMR_S 1118, Strasbourg, France.,INSERM, U1118, Mécanismes Centraux et Péripheriques de la Neurodégénérescence, Strasbourg, France
| | - Luc Dupuis
- Université de Strasbourg, UMR_S 1118, Strasbourg, France.,INSERM, U1118, Mécanismes Centraux et Péripheriques de la Neurodégénérescence, Strasbourg, France
| | - Jose-Luis Gonzalez De Aguilar
- Université de Strasbourg, UMR_S 1118, Strasbourg, France.,INSERM, U1118, Mécanismes Centraux et Péripheriques de la Neurodégénérescence, Strasbourg, France
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21
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de Carvalho M, Swash M. Lower motor neuron dysfunction in ALS. Clin Neurophysiol 2016; 127:2670-81. [DOI: 10.1016/j.clinph.2016.03.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/08/2016] [Accepted: 03/01/2016] [Indexed: 12/11/2022]
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22
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Acetylcholine receptors from human muscle as pharmacological targets for ALS therapy. Proc Natl Acad Sci U S A 2016; 113:3060-5. [PMID: 26929355 DOI: 10.1073/pnas.1600251113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting motor neurons that leads to progressive paralysis of skeletal muscle. Studies of ALS have revealed defects in expression of acetylcholine receptors (AChRs) in skeletal muscle that occur even in the absence of motor neuron anomalies. The endocannabinoid palmitoylethanolamide (PEA) modified the clinical conditions in one ALS patient, improving muscle force and respiratory efficacy. By microtransplanting muscle membranes from selected ALS patients into Xenopus oocytes, we show that PEA reduces the desensitization of acetylcholine-evoked currents after repetitive neurotransmitter application (i.e., rundown). The same effect was observed using muscle samples from denervated (non-ALS) control patients. The expression of human recombinant α1β1γδ (γ-AChRs) and α1β1εδ AChRs (ε-AChRs) in Xenopus oocytes revealed that PEA selectively affected the rundown of ACh currents in ε-AChRs. A clear up-regulation of the α1 subunit in muscle from ALS patients compared with that from non-ALS patients was found by quantitative PCR, but no differential expression was found for other subunits. Clinically, ALS patients treated with PEA showed a lower decrease in their forced vital capacity (FVC) over time as compared with untreated ALS patients, suggesting that PEA can enhance pulmonary function in ALS. In the present work, data were collected from a cohort of 76 ALS patients and 17 denervated patients. Our results strengthen the evidence for the role of skeletal muscle in ALS pathogenesis and pave the way for the development of new drugs to hamper the clinical effects of the disease.
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Puttonen KA, Ruponen M, Naumenko N, Hovatta OH, Tavi P, Koistinaho J. Generation of Functional Neuromuscular Junctions from Human Pluripotent Stem Cell Lines. Front Cell Neurosci 2015; 9:473. [PMID: 26696831 PMCID: PMC4672046 DOI: 10.3389/fncel.2015.00473] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/20/2015] [Indexed: 12/12/2022] Open
Abstract
Several neuromuscular diseases involve dysfunction of neuromuscular junctions (NMJs), yet there are no patient-specific human models for electrophysiological characterization of NMJ. We seeded cells of neurally-induced embryoid body-like spheres derived from induced pluripotent stem cell (iPSC) or embryonic stem cell (ESC) lines as monolayers without basic fibroblast factor (bFGF) and observed differentiation of neuronal as well as spontaneously contracting, multinucleated skeletal myotubes. The myotubes showed striation, immunoreactivity for myosin heavy chain, actin bundles typical for myo-oriented cells, and generated spontaneous and evoked action potentials (APs). The myogenic differentiation was associated with expression of MyoD1, myogenin and type I ryanodine receptor. Neurons formed end plate like structures with strong binding of α-bungarotoxin, a marker of nicotinic acetylcholine receptors highly expressed in the postsynaptic membrane of NMJs, and expressed SMI-32, a motoneuron marker, as well as SV2, a marker for synapses. Pharmacological stimulation of cholinergic receptors resulted in strong depolarization of myotube membrane and raised Ca2+ concentration in sarcoplasm, while electrical stimulation evoked Ca2+ transients in myotubes. Stimulation of motoneurons with N-Methyl-D-aspartate resulted in reproducible APs in myotubes and end plates displayed typical mEPPs and tonic activity depolarizing myotubes of about 10 mV. We conclude that simultaneous differentiation of neurons and myotubes from patient-specific iPSCs or ESCs results also in the development of functional NMJs. Our human model of NMJ may serve as an important tool to investigate normal development, mechanisms of diseases and novel drug targets involving NMJ dysfunction and degeneration.
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Affiliation(s)
- Katja A Puttonen
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
| | - Marika Ruponen
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland ; School of Pharmacy, University of Eastern Finland Kuopio, Finland
| | - Nikolay Naumenko
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
| | - Outi H Hovatta
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet Stockholm, Sweden
| | - Pasi Tavi
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
| | - Jari Koistinaho
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland Kuopio, Finland
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24
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Crespin L, Legros C, List O, Tricoire-Leignel H, Mattei C. Injection of insect membrane in Xenopus oocyte: An original method for the pharmacological characterization of neonicotinoid insecticides. J Pharmacol Toxicol Methods 2015; 77:10-6. [PMID: 26391340 DOI: 10.1016/j.vascn.2015.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/04/2015] [Accepted: 09/15/2015] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Insect nicotinic acetylcholine receptors (nAChRs) represent a major target of insecticides, belonging to the neonicotinoid family. However, the pharmacological profile of native nAChRs is poorly documented, mainly because of a lack of knowledge of their subunit stoichiometry, their tissue distribution and the weak access to nAChR-expressing cells. In addition, the expression of insect nAChRs in heterologous systems remains hard to achieve. Therefore, the structure-activity characterization of nAChR-targeting insecticides is made difficult. The objective of the present study was to characterize insect nAChRs by an electrophysiological approach in a heterologous system naturally devoid of these receptors to allow a molecular/cellular investigation of the mode of action of neonicotinoids. Methods To overcome impediments linked to the expression of insect nAChR mRNA or cDNA, we chose to inject insect membranes from the pea aphid (Acyrthosiphon pisum) into Xenopus oocytes. This microtransplantation technique was designed to gain access to native nAChRs embedded in their membrane, through direct stimulation with nicotinic agonists. Results We provide evidence that an enriched-nAChR membrane allows us to characterize native receptors. The presence of such receptors was confirmed with fluorescent α-BgTX labeling. Electrophysiological recordings of nicotine-induced inward currents allowed us to challenge the presence of functional nAChR. We compared the effect of nicotine (NIC) with clothianidin (CLO) and we assessed the effect of thiamethoxam (TMX). Discussion This technique has been recently highlighted with mammalian and human material as a powerful functional approach, but has, to our knowledge, never been used with insect membrane. In addition, the use of the insect membrane microtransplantation opens a new and original way for pharmacological screening of neurotoxic insecticides, including neonicotinoids. Moreover, it might also be a powerful tool to investigate the pharmacological properties of insect nAChR.
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Affiliation(s)
- Lucille Crespin
- Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée CNRS UMR6214, INSERM U1083, Univ. Angers Faculté de Médecine, rue Haute de Reculée, 49045 Angers cedex 01, France
| | - Christian Legros
- Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée CNRS UMR6214, INSERM U1083, Univ. Angers Faculté de Médecine, rue Haute de Reculée, 49045 Angers cedex 01, France
| | - Olivier List
- Récepteurs et Canaux Ioniques Membranaires, UPRES-EA 2647 USC INRA 1330, SFR 4207 QUASAV, Univ. Angers, 2 Bd Lavoisier, 49045 Angers cedex 01, France
| | - Hélène Tricoire-Leignel
- INRA/Université d'Angers, Neuroéthologie-RCIM, UPRES-EA 2647 USC INRA 1330, SFR 4207 QUASAV, 42, rue Georges Morel, 49071 Beaucouzé, France.
| | - César Mattei
- Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée CNRS UMR6214, INSERM U1083, Univ. Angers Faculté de Médecine, rue Haute de Reculée, 49045 Angers cedex 01, France.
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Partial block by riluzole of muscle sodium channels in myotubes from amyotrophic lateral sclerosis patients. Neurol Res Int 2014; 2014:946073. [PMID: 25548669 PMCID: PMC4273590 DOI: 10.1155/2014/946073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/18/2014] [Indexed: 12/13/2022] Open
Abstract
Denervated muscles undergo fibrillations due to spontaneous activation of voltage-gated sodium (Na(+)) channels generating action potentials. Fibrillations also occur in patients with amyotrophic lateral sclerosis (ALS). Riluzole, the only approved drug for ALS treatment, blocks voltage-gated Na(+) channels, but its effects on muscle Na(+) channels and fibrillations are yet poorly characterized. Using patch-clamp technique, we studied riluzole effect on Na(+) channels in cultured myotubes from ALS patients. Needle electromyography was used to study fibrillation potentials (Fibs) in ALS patients during riluzole treatment and after one week of suspension. Patients were clinically characterized in all recording sessions. In myotubes, riluzole (1 μM, a therapeutic concentration) reduced Na(+) current by 20%. The rate of rise and amplitude of spikes evoked by depolarizing stimuli were also reduced. Fibs were detected in all patients tested during riluzole treatment and riluzole washout had no univocal effect. Our study indicates that, in human myotubes, riluzole partially blocks Na(+) currents and affects action potentials but does not prevent firing. In line with this in vitro finding, muscle Fibs in ALS patients appear to be largely unaffected by riluzole.
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Malaspina A, Puentes F, Amor S. Disease origin and progression in amyotrophic lateral sclerosis: an immunology perspective. Int Immunol 2014; 27:117-29. [DOI: 10.1093/intimm/dxu099] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Guo X, Greene K, Akanda N, Smith A, Stancescu M, Lambert S, Vandenburgh H, Hickman J. In vitro Differentiation of Functional Human Skeletal Myotubes in a Defined System. Biomater Sci 2014; 2:131-138. [PMID: 24516722 DOI: 10.1039/c3bm60166h] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In vitro human skeletal muscle systems are valuable tools for the study of human muscular development, disease and treatment. However, published in vitro human muscle systems have so far only demonstrated limited differentiation capacities. Advanced differentiation features such as cross-striations and contractility have only been observed in co-cultures with motoneurons. Furthermore, it is commonly regarded that cultured human myotubes do not spontaneously contract, and any contraction has been considered to originate from innervation. This study developed a serum-free culture system in which human skeletal myotubes demonstrated advanced differentiation. Characterization by immunocytochemistry, electrophysiology and analysis of contractile function revealed these major features: A) well defined sarcomeric development, as demonstrated by the presence of cross-striations. B) finely developed excitation-contraction coupling apparatus characterized by the close apposition of dihydropyridine receptors on T-tubules and Ryanodine receptors on sarcoplasmic reticulum membranes. C) spontaneous and electrically controlled contractility. This report not only demonstrates an improved level of differentiation of cultured human skeletal myotubes, but also provides the first published evidence that such myotubes are capable of spontaneous contraction. Use of this functional in vitro human skeletal muscle system would advance studies concerning human skeletal muscle development and physiology, as well as muscle-related disease and therapy.
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Affiliation(s)
- Xiufang Guo
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA
| | - Keshel Greene
- Biomolecular Science Center, Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida 32826, USA
| | - Nesar Akanda
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA
| | - Alec Smith
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA
| | - Maria Stancescu
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA ; Department of Chemistry, 4000 Central Florida Blvd., Physical Sciences Building (PS) Room 255, University of Central Florida, Orlando, FL 32816-2366, USA
| | - Stephen Lambert
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA ; College of Medicine, University of Central Florida, 12201 Research Parkway, Suite 479, Room 463, Orlando, FL 32826, USA
| | - Herman Vandenburgh
- Brown University, Professor Emeritus, Department of Pathology and Lab Medicine, Providence, Rhode Island, 02913 USA ; Myomics, 148 West River Str, Providence, Rhode Island 02904
| | - James Hickman
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, USA ; Biomolecular Science Center, Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida 32826, USA ; Department of Chemistry, 4000 Central Florida Blvd., Physical Sciences Building (PS) Room 255, University of Central Florida, Orlando, FL 32816-2366, USA
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Advances in cellular models to explore the pathophysiology of amyotrophic lateral sclerosis. Mol Neurobiol 2013; 49:966-83. [PMID: 24198229 DOI: 10.1007/s12035-013-8573-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 10/15/2013] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disorder, is fatal for most patients less than 3 years from when the first symptoms appear. The aetiologies for sporadic and most familial forms of ALS are unknown, but genetic factors are increasingly recognized as causal in a subset of patients. Studies of disease physiology suggest roles for oxidative stress, glutamate-mediated excitotoxicity or protein aggregation; how these pathways interact in the complex pathophysiology of ALS awaits elucidation. Cellular models are being used to examine disease mechanisms. Recent advances include the availability of expanded cell types, from neuronal or glial cell culture to motoneuron-astrocyte co-culture genetically or environmentally modified. Cell culture experiments confirmed the central role of glial cells in ALS. The recent adaptation of induced pluripotent stem cells (iPSC) for ALS modeling could allow a broader perspective and is expected to generate new hypotheses, related particularly to mechanisms underlying genetic factors. Cellular models have provided meaningful advances in the understanding of ALS, but, to date, complete characterization of in vitro models is only partially described. Consensus on methodological approaches, strategies for validation and techniques that allow rapid adaptation to new genetic or environmental influences is needed. In this article, we review the principal cellular models being employed in ALS and highlight their contribution to the understanding of disease mechanisms. We conclude with recommendations on means to enhance the robustness and generalizability of the different concepts for experimental ALS.
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Focant MC, Hermans E. Protein interacting with C kinase and neurological disorders. Synapse 2013; 67:532-40. [DOI: 10.1002/syn.21657] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 02/16/2013] [Indexed: 01/15/2023]
Affiliation(s)
- Marylène C. Focant
- Institute of Neuroscience, Université catholique de Louvain; Brussels; Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Université catholique de Louvain; Brussels; Belgium
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Jarecki BW, Makino SI, Beebe ET, Fox BG, Chanda B. Function of Shaker potassium channels produced by cell-free translation upon injection into Xenopus oocytes. Sci Rep 2013; 3:1040. [PMID: 23301161 PMCID: PMC3539143 DOI: 10.1038/srep01040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 12/06/2012] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated ion channels are a class of membrane proteins that temporally orchestrate the ion flux critical for chemical and electrical signaling in excitable cells. Current methods to investigate the function of these channels rely on heterologous expression in living systems or reconstitution into artificial membranes; however these approaches have inherent drawbacks which limit potential biophysical applications. Here, we describe a new integrated approach combining cell-free translation of membrane proteins and in vivo expression using Xenopus laevis oocytes. In this method, proteoliposomes containing Shaker potassium channels are synthesized in vitro and injected into the oocytes, yielding functional preparations as shown by electrophysiological and fluorescence measurements within few hours. This strategy for studying eukaryotic ion channels is contrasted with existing, laborious procedures that require membrane protein extraction and reconstitution into synthetic lipid systems.
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Affiliation(s)
- Brian W Jarecki
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53706, USA
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Deflorio C, Palma E, Conti L, Roseti C, Manteca A, Giacomelli E, Catalano M, Limatola C, Inghilleri M, Grassi F. Riluzole blocks human muscle acetylcholine receptors. J Physiol 2012; 590:2519-28. [PMID: 22431338 DOI: 10.1113/jphysiol.2012.230201] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Riluzole, the only drug available against amyotrophic lateral sclerosis (ALS), has recently been shown to block muscle ACh receptors (AChRs), raising concerns about possible negative side-effects on neuromuscular transmission in treated patients. In this work we studied riluzole's impact on the function of muscle AChRs in vitro and on neuromuscular transmission in ALS patients, using electrophysiological techniques. Human recombinant AChRs composed of α(1)β(1)δ subunits plus the γ or ε subunit (γ- or ε-AChR) were expressed in HEK cells or Xenopus oocytes. In both preparations, riluzole at 0.5 μm, a clinically relevant concentration, reversibly reduced the amplitude and accelerated the decay of ACh-evoked current if applied before coapplication with ACh. The action on γ-AChRs was more potent and faster than on ε-AChRs. In HEK outside-out patches, riluzole-induced block of macroscopic ACh-evoked current gradually developed during the initial milliseconds of ACh presence. Single channel recordings in HEK cells and in human myotubes from ALS patients showed that riluzole prolongs channel closed time, but has no effect on channel conductance and open duration. Finally, compound muscle action potentials (CMAPs) evoked by nerve stimulation in ALS patients remained unaltered after a 1 week suspension of riluzole treatment. These data indicate that riluzole, while apparently safe with regard to synaptic transmission, may affect the function of AChRs expressed in denervated muscle fibres of ALS patients, with biological consequences that remain to be investigated.
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Affiliation(s)
- Cristina Deflorio
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
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