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Cadile F, Recchia D, Ansaldo M, Rossi P, Rastelli G, Boncompagni S, Brocca L, Pellegrino MA, Canepari M. Diaphragm Fatigue in SMNΔ7 Mice and Its Molecular Determinants: An Underestimated Issue. Int J Mol Sci 2023; 24:14953. [PMID: 37834400 PMCID: PMC10574014 DOI: 10.3390/ijms241914953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a genetic disorder characterized by the loss of spinal motor neurons leading to muscle weakness and respiratory failure. Mitochondrial dysfunctions are found in the skeletal muscle of patients with SMA. For obvious ethical reasons, the diaphragm muscle is poorly studied, notwithstanding the very important role that respiratory involvement plays in SMA mortality. The main goal of this study was to investigate diaphragm functionality and the underlying molecular adaptations in SMNΔ7 mice, a mouse model that exhibits symptoms similar to that of patients with intermediate type II SMA. Functional, biochemical, and molecular analyses on isolated diaphragm were performed. The obtained results suggest the presence of an intrinsic energetic imbalance associated with mitochondrial dysfunction and a significant accumulation of reactive oxygen species (ROS). In turn, ROS accumulation can affect muscle fatigue, cause diaphragm wasting, and, in the long run, respiratory failure in SMNΔ7 mice. Exposure to the antioxidant molecule ergothioneine leads to the functional recovery of the diaphragm, confirming the presence of mitochondrial impairment and redox imbalance. These findings suggest the possibility of carrying out a dietary supplementation in SMNΔ7 mice to preserve their diaphragm function and increase their lifespan.
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Affiliation(s)
- Francesca Cadile
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Deborah Recchia
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Massimiliano Ansaldo
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Paola Rossi
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (D.R.); (P.R.)
| | - Giorgia Rastelli
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
| | - Simona Boncompagni
- Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy; (G.R.); (S.B.)
- Department of Neuroscience, Imaging and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, 66100 Chieti, Italy
| | - Lorenza Brocca
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
| | - Monica Canepari
- Department of Molecular Medicine, via Forlanini 6, University of Pavia, 27100 Pavia, Italy; (F.C.); (M.A.); (L.B.); (M.A.P.)
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Morotti M, Gaeta A, Limatola C, Catalano M, Di Castro MA, Grassi F. Early Developmental Changes of Muscle Acetylcholine Receptors Are Little Influenced by Dystrophin Absence in mdx Mouse. LIFE (BASEL, SWITZERLAND) 2022; 12:life12111861. [PMID: 36430996 PMCID: PMC9696329 DOI: 10.3390/life12111861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022]
Abstract
Dystrophin is a cytoskeletal protein contributing to the organization of the neuromuscular junction. In Duchenne muscular dystrophy, due to dystrophin absence, the distribution of endplate acetylcholine receptors (AChRs) becomes disorganized. It is still debated whether this is due to the absence of dystrophin or to the repeated damage/regeneration cycles typical of dystrophic muscle. We addressed this controversy studying the endplate in the first 3 postnatal weeks, when muscle damage in dystrophic (mdx) mice is minimal. By synaptic and extra-synaptic patch-clamp recordings in acutely dissociated mdx and wt muscle fibers, we recorded unitary events due to openings of AChR-channels containing the γ and ε subunit. We also examined AChR distribution at the endplate by immunofluorescence assays. No differences between wt and mdx fibers were found in the γ/ε switch, nor in the AChR organization at the endplates up to 21 postnatal days. Conversely, we detected a delayed appearance and disappearance of patches with high channel opening frequency in mdx fibers. Our data emphasize that the innervation-dependent γ/ε switch and AChR organization in the endplate are not affected by the absence of dystrophin, while extra-synaptic AChR cluster formation and disassembly could be differentially regulated in mdx mice.
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Affiliation(s)
- Marta Morotti
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
| | - Alessandro Gaeta
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
| | - Cristina Limatola
- Laboratory Affiliated to Istituto Pasteur Italia, Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, 86077 Pozzilli, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
| | - Maria Amalia Di Castro
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
| | - Francesca Grassi
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy
- Correspondence:
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Zou S, Pan BX. Post-synaptic specialization of the neuromuscular junction: junctional folds formation, function, and disorders. Cell Biosci 2022; 12:93. [PMID: 35718785 PMCID: PMC9208267 DOI: 10.1186/s13578-022-00829-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/05/2022] [Indexed: 11/14/2022] Open
Abstract
Post-synaptic specialization is critical to the neurotransmitter release and action potential conduction. The neuromuscular junctions (NMJs) are the synapses between the motor neurons and muscle cells and have a more specialized post-synaptic membrane than synapses in the central nervous system (CNS). The sarcolemma within NMJ folded to form some invagination portions called junctional folds (JFs), and they have important roles in maintaining the post-synaptic membrane structure. The NMJ formation and the acetylcholine receptor (AChR) clustering signal pathway have been extensively studied and reviewed. Although it has been suggested that JFs are related to maintaining the safety factor of neurotransmitter release, the formation mechanism and function of JFs are still unclear. This review will focus on the JFs about evolution, formation, function, and disorders. Anticipate understanding of where they are coming from and where we will study in the future.
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Affiliation(s)
- Suqi Zou
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China.
- School of Life Sciences, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China.
| | - Bing-Xing Pan
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China
- School of Life Sciences, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China
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James R, Chaytow H, Ledahawsky LM, Gillingwater TH. Revisiting the role of mitochondria in spinal muscular atrophy. Cell Mol Life Sci 2021; 78:4785-4804. [PMID: 33821292 PMCID: PMC8195803 DOI: 10.1007/s00018-021-03819-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/22/2021] [Accepted: 03/23/2021] [Indexed: 02/07/2023]
Abstract
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease of variable clinical severity that is caused by mutations in the survival motor neuron 1 (SMN1) gene. Despite its name, SMN is a ubiquitous protein that functions within and outside the nervous system and has multiple cellular roles in transcription, translation, and proteostatic mechanisms. Encouragingly, several SMN-directed therapies have recently reached the clinic, albeit this has highlighted the increasing need to develop combinatorial therapies for SMA to achieve full clinical efficacy. As a subcellular site of dysfunction in SMA, mitochondria represents a relevant target for a combinatorial therapy. Accordingly, we will discuss our current understanding of mitochondrial dysfunction in SMA, highlighting mitochondrial-based pathways that offer further mechanistic insights into the involvement of mitochondria in SMA. This may ultimately facilitate translational development of targeted mitochondrial therapies for SMA. Due to clinical and mechanistic overlaps, such strategies may also benefit other motor neuron diseases and related neurodegenerative disorders.
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Affiliation(s)
- Rachel James
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Helena Chaytow
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Leire M Ledahawsky
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9XD, UK.
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, UK.
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Somatic Therapy of a Mouse SMA Model with a U7 snRNA Gene Correcting SMN2 Splicing. Mol Ther 2016; 24:1797-1805. [PMID: 27456062 PMCID: PMC5112044 DOI: 10.1038/mt.2016.152] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/18/2016] [Indexed: 12/12/2022] Open
Abstract
Spinal Muscular Atrophy is due to the loss of SMN1 gene function. The duplicate gene SMN2 produces some, but not enough, SMN protein because most transcripts lack exon 7. Thus, promoting the inclusion of this exon is a therapeutic option. We show that a somatic gene therapy using the gene for a modified U7 RNA which stimulates this splicing has a profound and persistent therapeutic effect on the phenotype of a severe Spinal Muscular Atrophy mouse model. To this end, the U7 gene and vector and the production of pure, highly concentrated self-complementary (sc) adenovirus-associated virus 9 vector particles were optimized. Introduction of the functional vector into motoneurons of newborn Spinal Muscular Atrophy mice by intracerebroventricular injection led to a highly significant, dose-dependent increase in life span and improvement of muscle functions. Besides the central nervous system, the therapeutic U7 RNA was expressed in the heart and liver which may additionally have contributed to the observed therapeutic efficacy. This approach provides an additional therapeutic option for Spinal Muscular Atrophy and could also be adapted to treat other diseases of the central nervous system with regulatory small RNA genes.
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Neve A, Trüb J, Saxena S, Schümperli D. Central and peripheral defects in motor units of the diaphragm of spinal muscular atrophy mice. Mol Cell Neurosci 2016; 70:30-41. [PMID: 26621405 DOI: 10.1016/j.mcn.2015.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/30/2015] [Accepted: 11/23/2015] [Indexed: 01/08/2023] Open
Abstract
Spinal muscular atrophy (SMA) is characterized by motoneuron loss and muscle weakness. However, the structural and functional deficits that lead to the impairment of the neuromuscular system remain poorly defined. By electron microscopy, we previously found that neuromuscular junctions (NMJs) and muscle fibres of the diaphragm are among the earliest affected structures in the severe mouse SMA model. Because of certain anatomical features, i.e. its thinness and its innervation from the cervical segments of the spinal cord, the diaphragm is particularly suitable to characterize both central and peripheral events. Here we show by immunohistochemistry that, at postnatal day 3, the cervical motoneurons of SMA mice receive less stimulatory synaptic inputs. Moreover, their mitochondria become less elongated which might represent an early stage of degeneration. The NMJs of the diaphragm of SMA mice show a loss of synaptic vesicles and active zones. Moreover, the partly innervated endplates lack S100 positive perisynaptic Schwann cells (PSCs). We also demonstrate the feasibility of comparing the proteomic composition between diaphragm regions enriched and poor in NMJs. By this approach we have identified two proteins that are significantly upregulated only in the NMJ-specific regions of SMA mice. These are apoptosis inducing factor 1 (AIFM1), a mitochondrial flavoprotein that initiates apoptosis in a caspase-independent pathway, and four and a half Lim domain protein 1 (FHL1), a regulator of skeletal muscle mass that has been implicated in several myopathies.
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Affiliation(s)
- Anuja Neve
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Judith Trüb
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | - Smita Saxena
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | - Daniel Schümperli
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
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Huo Q, Kayikci M, Odermatt P, Meyer K, Michels O, Saxena S, Ule J, Schümperli D. Splicing changes in SMA mouse motoneurons and SMN-depleted neuroblastoma cells: evidence for involvement of splicing regulatory proteins. RNA Biol 2015; 11:1430-46. [PMID: 25692239 PMCID: PMC4601534 DOI: 10.1080/15476286.2014.996494] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spinal Muscular Atrophy (SMA) is caused by deletions or mutations in the Survival Motor Neuron 1 (SMN1) gene. The second gene copy, SMN2, produces some, but not enough, functional SMN protein. SMN is essential to assemble small nuclear ribonucleoproteins (snRNPs) that form the spliceosome. However, it is not clear whether SMA is caused by defects in this function that could lead to splicing changes in all tissues, or by the impairment of an additional, less well characterized, but motoneuron-specific SMN function. We addressed the first possibility by exon junction microarray analysis of motoneurons (MNs) isolated by laser capture microdissection from a severe SMA mouse model. This revealed changes in multiple U2-dependent splicing events. Moreover, splicing appeared to be more strongly affected in MNs than in other cells. By testing mutiple genes in a model of progressive SMN depletion in NB2a neuroblastoma cells, we obtained evidence that U2-dependent splicing changes occur earlier than U12-dependent ones. As several of these changes affect genes coding for splicing regulators, this may acerbate the splicing response induced by low SMN levels and induce secondary waves of splicing alterations.
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Key Words
- ESE, exonic splicing enhancer
- FCS, fetal calf serum
- MN, motoneuron
- NMD, nonsense-mediated mRNA decay
- NMJ, neuromuscular junction, PCR
- RT, reverse transcription
- SMA, Spinal Muscular Atrophy
- SMN, Survival Motor Neuron
- Spinal Muscular Atrophy
- TcRβ, T-cell receptor β chain
- exon junction microarray
- hz, heterozygote, LCM
- laser capture microdissection
- major spliceosome
- minor spliceosome
- motoneurons
- neurodegerative disease
- polymerase chain reaction, qPCR
- real-time (quantitative) PCR
- sh, short hairpin
- snRNA, small nuclear ribonucleic acid
- snRNP assembly
- snRNP, small nuclear ribonucleoprotein
- splicing
- splicing regulators
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Affiliation(s)
- Qing Huo
- a Institute of Cell Biology ; University of Bern ; Bern , Switzerland
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