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Balanyà-Segura M, Polishchuk A, Just-Borràs L, Cilleros-Mañé V, Silvera C, Ardévol A, Tomàs M, Lanuza MA, Hurtado E, Tomàs J. Molecular Adaptations of BDNF/NT-4 Neurotrophic and Muscarinic Pathways in Ageing Neuromuscular Synapses. Int J Mol Sci 2024; 25:8018. [PMID: 39125587 PMCID: PMC11311581 DOI: 10.3390/ijms25158018] [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: 05/31/2024] [Revised: 07/05/2024] [Accepted: 07/09/2024] [Indexed: 08/12/2024] Open
Abstract
Age-related conditions, such as sarcopenia, cause physical disabilities for an increasing section of society. At the neuromuscular junction, the postsynaptic-derived neurotrophic factors brain-derived neurotrophic factor (BDNF) and neurotrophin 4 (NT-4) have neuroprotective functions and contribute to the correct regulation of the exocytotic machinery. Similarly, presynaptic muscarinic signalling plays a fundamental modulatory function in this synapse. However, whether or not these signalling pathways are compromised in ageing neuromuscular system has not yet been analysed. The present study analyses, through Western blotting, the differences in expression and activation of the main key proteins of the BDNF/NT-4 and muscarinic pathways related to neurotransmission in young versus ageing Extensor digitorum longus (EDL) rat muscles. The main results show an imbalance in several sections of these pathways: (i) a change in the stoichiometry of BDNF/NT-4, (ii) an imbalance of Tropomyosin-related kinase B receptor (TrkB)-FL/TrkB-T1 and neurotrophic receptor p 75 (p75NTR), (iii) no changes in the cytosol/membrane distribution of phosphorylated downstream protein kinase C (PKC)βI and PKCε, (iv) a reduction in the M2-subtype muscarinic receptor and P/Q-subtype voltage-gated calcium channel, (v) an imbalance of phosphorylated mammalian uncoordinated-18-1 (Munc18-1) (S313) and synaptosomal-associated protein 25 (SNAP-25) (S187), and (vi) normal levels of molecules related to the management of acetylcholine (Ach). Based on this descriptive analysis, we hypothesise that these pathways can be adjusted to ensure neurotransmission rather than undergoing negative alterations caused by ageing. However, further studies are needed to assess this hypothetical suggestion. Our results contribute to the understanding of some previously described neuromuscular functional age-related impairments. Strategies to promote these signalling pathways could improve the neuromuscular physiology and quality of life of older people.
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Affiliation(s)
- Marta Balanyà-Segura
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Aleksandra Polishchuk
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Laia Just-Borràs
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Víctor Cilleros-Mañé
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Carolina Silvera
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Anna Ardévol
- MoBioFood Research Group, Campus Sescelades, Universitat Rovira i Virgili, Marcel.lí Domingo 1, 43007 Tarragona, Spain;
| | - Marta Tomàs
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Maria A. Lanuza
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Erica Hurtado
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
| | - Josep Tomàs
- Unitat d’Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain; (M.B.-S.); (A.P.); (L.J.-B.); (V.C.-M.); (C.S.); (M.T.); (J.T.)
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Couturier N, Hörner SJ, Nürnberg E, Joazeiro C, Hafner M, Rudolf R. Aberrant evoked calcium signaling and nAChR cluster morphology in a SOD1 D90A hiPSC-derived neuromuscular model. Front Cell Dev Biol 2024; 12:1429759. [PMID: 38966427 PMCID: PMC11222430 DOI: 10.3389/fcell.2024.1429759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 06/03/2024] [Indexed: 07/06/2024] Open
Abstract
Familial amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disorder that is due to mutations in one of several target genes, including SOD1. So far, clinical records, rodent studies, and in vitro models have yielded arguments for either a primary motor neuron disease, or a pleiotropic pathogenesis of ALS. While mouse models lack the human origin, in vitro models using human induced pluripotent stem cells (hiPSC) have been recently developed for addressing ALS pathogenesis. In spite of improvements regarding the generation of muscle cells from hiPSC, the degree of maturation of muscle cells resulting from these protocols has remained limited. To fill these shortcomings, we here present a new protocol for an enhanced myotube differentiation from hiPSC with the option of further maturation upon coculture with hiPSC-derived motor neurons. The described model is the first to yield a combination of key myogenic maturation features that are consistent sarcomeric organization in association with complex nAChR clusters in myotubes derived from control hiPSC. In this model, myotubes derived from hiPSC carrying the SOD1 D90A mutation had reduced expression of myogenic markers, lack of sarcomeres, morphologically different nAChR clusters, and an altered nAChR-dependent Ca2+ response compared to control myotubes. Notably, trophic support provided by control hiPSC-derived motor neurons reduced nAChR cluster differences between control and SOD1 D90A myotubes. In summary, a novel hiPSC-derived neuromuscular model yields evidence for both muscle-intrinsic and nerve-dependent aspects of neuromuscular dysfunction in SOD1-based ALS.
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Affiliation(s)
- Nathalie Couturier
- CeMOS, Mannheim University of Applied Sciences, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Sarah Janice Hörner
- CeMOS, Mannheim University of Applied Sciences, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Elina Nürnberg
- CeMOS, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Claudio Joazeiro
- Center for Molecular Biology, Heidelberg University, Heidelberg, Germany
| | - Mathias Hafner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany
- Institute of Medical Technology, Mannheim University of Applied Sciences and Heidelberg University, Mannheim, Germany
| | - Rüdiger Rudolf
- CeMOS, Mannheim University of Applied Sciences, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany
- Institute of Medical Technology, Mannheim University of Applied Sciences and Heidelberg University, Mannheim, Germany
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Satori NA, Pacini ESA, Godinho RO. Impact of the cAMP efflux and extracellular cAMP-adenosine pathway on airway smooth muscle relaxation induced by formoterol and phosphodiesterase inhibitors. Chem Biol Interact 2023; 382:110630. [PMID: 37442289 DOI: 10.1016/j.cbi.2023.110630] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/22/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023]
Abstract
β2-adrenoceptors agonists and phosphodiesterase (PDE) inhibitors are effective bronchodilators, due to their ability to increase intracellular cyclic AMP (cAMP) levels and induce airway smooth muscle (ASM) relaxation. We have shown that increment of intracellular cAMP induced by β2-adrenoceptors agonist fenoterol is followed by efflux of cAMP, which is converted by ecto-PDE and ecto-5'-nucleotidases (ecto-5'NT) to adenosine, leading to ASM contraction. Here we evaluate whether other classical bronchodilators used to treat asthma and chronic obstructive pulmonary disease (COPD) could induce cAMP efflux and, as consequence, influence the ASM contractility. Our results showed that β2-adrenoceptor agonists formoterol and PDE inhibitors IBMX, aminophylline and roflumilast induced cAMP efflux and a concentration-dependent relaxation of rat trachea precontracted with carbachol. Pretreatment of tracheas with MK-571 (MRP transporter inhibitor), AMP-CP (ecto-5'NT inhibitor) or CGS-15943 (nonselective adenosine receptor antagonist) potentiated the relaxation induced by β2-adrenoceptor agonists but did not change the relaxation induced by PDE inhibitors. These data showed that all bronchodilators tested were able to induce cAMP efflux. However, only β2-adrenoceptor-induced relaxation of tracheal smooth muscle was affected by cAMP efflux and extracellular cAMP-adenosine pathway.
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Affiliation(s)
- Naiara Ayako Satori
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil
| | - Enio Setsuo Arakaki Pacini
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil
| | - Rosely Oliveira Godinho
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil.
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Maldonado L, Orozco-Aguilar J, Valero-Breton M, Tacchi F, Cifuentes-Silva E, Cabello-Verrugio C. Differential Fibrotic Response of Muscle Fibroblasts, Myoblasts, and Myotubes to Cholic and Deoxycholic Acids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1408:219-234. [PMID: 37093430 DOI: 10.1007/978-3-031-26163-3_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Fibrosis is a condition characterized by an increase in the components of the extracellular matrix (ECM). In skeletal muscle, the cells that participate in the synthesis of ECM are fibroblasts, myoblasts, and myotubes. These cells respond to soluble factors that increase ECM. Fibrosis is a phenomenon that develops in conditions of chronic inflammation, extensive lesions, or chronic diseases. A pathological condition with muscle weakness and increased bile acids (BA) in the blood is cholestatic chronic liver diseases (CCLD). Skeletal muscle expresses the membrane receptor for BA called TGR5. To date, muscle fibrosis in CCLD has not been evaluated. This study aims to assess whether BA can induce a fibrotic condition in muscle fibroblasts, myoblasts, and myotubes. The cells were incubated with deoxycholic (DCA) and cholic (CA) acids, and fibronectin protein levels were evaluated by Western blot. In muscle fibroblasts, both DCA and CA induced an increase in fibronectin protein levels. The same response was found in fibroblasts when activating TGR5 with the specific receptor agonist (INT-777). Interestingly, DCA reduced fibronectin protein levels in both myoblasts and myotubes, while CA did not show changes in fibronectin protein levels in myoblasts and myotubes. These results suggest that DCA and CA can induce a fibrotic phenotype in muscle-derived fibroblasts. On the other hand, DCA decreased the fibronectin in myoblasts and myotubes, whereas CA did not show any effect in these cell populations. Our results show that BA has different effects depending on the cell population to be analyzed.
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Affiliation(s)
- Luis Maldonado
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
| | - Josué Orozco-Aguilar
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
- Laboratorio de Ensayos Biológicos (LEBi), Universidad de Costa Rica, San José, Costa Rica
- Facultad de Farmacia, Universidad de Costa Rica, San José, Costa Rica
| | - Mayalen Valero-Breton
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
| | - Franco Tacchi
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
| | - Eduardo Cifuentes-Silva
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile
| | - Claudio Cabello-Verrugio
- Laboratory of Muscle Pathology, Fragility and Aging, Faculty of Life Sciences, Universidad Andres Bello, 8370146, Santiago, Chile.
- Faculty of Life Sciences, Millennium Institute on Immunology and Immunotherapy, Universidad Andres Bello, Santiago, Chile.
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago, Chile.
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Cilleros-Mañé V, Just-Borràs L, Tomàs M, Garcia N, Tomàs JM, Lanuza MA. The M 2 muscarinic receptor, in association to M 1 , regulates the neuromuscular PKA molecular dynamics. FASEB J 2020; 34:4934-4955. [PMID: 32052889 DOI: 10.1096/fj.201902113r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/23/2019] [Accepted: 01/20/2020] [Indexed: 01/13/2023]
Abstract
Muscarinic acetylcholine receptor 1 subtype (M1 ) and muscarinic acetylcholine receptor 2 subtype (M2 ) presynaptic muscarinic receptor subtypes increase and decrease, respectively, neurotransmitter release at neuromuscular junctions. M2 involves protein kinase A (PKA), although the muscarinic regulation to form and inactivate the PKA holoenzyme is unknown. Here, we show that M2 signaling inhibits PKA by downregulating Cβ subunit, upregulating RIIα/β and liberating RIβ and RIIα to the cytosol. This promotes PKA holoenzyme formation and reduces the phosphorylation of the transmitter release target synaptosome-associated protein 25 and the gene regulator cAMP response element binding. Instead, M1 signaling, which is downregulated by M2 , opposes to M2 by recruiting R subunits to the membrane. The M1 and M2 reciprocal actions are performed through the anchoring protein A kinase anchor protein 150 as a common node. Interestingly, M2 modulation on protein expression needs M1 signaling. Altogether, these results describe the dynamics of PKA subunits upon M2 muscarinic signaling in basal and under presynaptic nerve activity, uncover a specific involvement of the M1 receptor and reveal the M1 /M2 balance to activate PKA to regulate neurotransmission. This provides a molecular mechanism to the PKA holoenzyme formation and inactivation which could be general to other synapses and cellular models.
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Affiliation(s)
- Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Josep Maria Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Maria Angel Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
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Bernareggi A, Sciancalepore M, Lorenzon P. Interplay Between Cholinergic and Adenosinergic Systems in Skeletal Muscle. Neuroscience 2019; 439:41-47. [PMID: 31121259 DOI: 10.1016/j.neuroscience.2019.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 02/06/2023]
Abstract
Since the pioneering works of Ricardo Miledi, the neuromuscular junction represents the best example of a synapse where ACh is the neurotransmitter acting on nicotinic ACh receptors. ATP, co-released with ACh, is promptly degraded to Ado, which acts as a modulator of the cholinergic synaptic activity. Consequently, both ACh and adenosine play a crucial role in controlling the nerve-muscle communication. Apart from their role in the context of synaptic transmission, ACh and adenosine are autocrinally released by skeletal muscle cells, suggesting also a non nerve-driven function of these molecules. Indeed, the existence of cholinergic and adenosinergic systems has been widely described in many other non neuronal cell types. In this review, we will describe the two systems and their interplay in non-innervated differentiating skeletal muscle cells, and in innervated adult skeletal muscle fibers. We believe that the better comprehension of the interactions between the activity of nAChRs and adenosine could help the knowledge of skeletal muscle physiology. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy.
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, Trieste, Italy; B.R.A.I.N., Centre for Neuroscience, Trieste, Italy
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Pochaev VA, Krasnyi AM, Ozernyuk ND. Influx of Ca2+ via Cav1.3 calcium channels in satellite cells of muscle fibers in rats. BIOL BULL+ 2013. [DOI: 10.1134/s1062359013050129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ricotti L, Fujie T, Vazão H, Ciofani G, Marotta R, Brescia R, Filippeschi C, Corradini I, Matteoli M, Mattoli V, Ferreira L, Menciassi A. Boron nitride nanotube-mediated stimulation of cell co-culture on micro-engineered hydrogels. PLoS One 2013; 8:e71707. [PMID: 23977119 PMCID: PMC3743765 DOI: 10.1371/journal.pone.0071707] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/02/2013] [Indexed: 11/18/2022] Open
Abstract
In this paper, we describe the effects of the combination of topographical, mechanical, chemical and intracellular electrical stimuli on a co-culture of fibroblasts and skeletal muscle cells. The co-culture was anisotropically grown onto an engineered micro-grooved (10 µm-wide grooves) polyacrylamide substrate, showing a precisely tuned Young’s modulus (∼ 14 kPa) and a small thickness (∼ 12 µm). We enhanced the co-culture properties through intracellular stimulation produced by piezoelectric nanostructures (i.e., boron nitride nanotubes) activated by ultrasounds, thus exploiting the ability of boron nitride nanotubes to convert outer mechanical waves (such as ultrasounds) in intracellular electrical stimuli, by exploiting the direct piezoelectric effect. We demonstrated that nanotubes were internalized by muscle cells and localized in both early and late endosomes, while they were not internalized by the underneath fibroblast layer. Muscle cell differentiation benefited from the synergic combination of topographical, mechanical, chemical and nanoparticle-based stimuli, showing good myotube development and alignment towards a preferential direction, as well as high expression of genes encoding key proteins for muscle contraction (i.e., actin and myosin). We also clarified the possible role of fibroblasts in this process, highlighting their response to the above mentioned physical stimuli in terms of gene expression and cytokine production. Finally, calcium imaging-based experiments demonstrated a higher functionality of the stimulated co-cultures.
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Affiliation(s)
- Leonardo Ricotti
- The BioRobotics Institute, Scuola Superiore Sant’Anna, Pontedera, Pisa, Italy
- * E-mail:
| | - Toshinori Fujie
- Center of MicroBioRobotics @ SSSA, Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy
- WPI - Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Helena Vazão
- Biocant - Center of Biotechnology Innovation Center, Cantanhede, Coimbra, Portugal
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Gianni Ciofani
- Center of MicroBioRobotics @ SSSA, Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy
| | | | | | - Carlo Filippeschi
- The BioRobotics Institute, Scuola Superiore Sant’Anna, Pontedera, Pisa, Italy
- Center of MicroBioRobotics @ SSSA, Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy
| | - Irene Corradini
- Fondazione Filarete, Milano, Italy
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milano, Italy
| | - Michela Matteoli
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milano, Italy
- Humanitas Clinical and Research Center, Rozzano, Italy
| | - Virgilio Mattoli
- Center of MicroBioRobotics @ SSSA, Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy
| | - Lino Ferreira
- Biocant - Center of Biotechnology Innovation Center, Cantanhede, Coimbra, Portugal
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Arianna Menciassi
- The BioRobotics Institute, Scuola Superiore Sant’Anna, Pontedera, Pisa, Italy
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The cholinergic and non-cholinergic effects of organophosphates and oximes in cultured human myoblasts. Chem Biol Interact 2013; 203:144-8. [DOI: 10.1016/j.cbi.2012.09.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/07/2012] [Accepted: 09/10/2012] [Indexed: 11/18/2022]
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10
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Zhu H, Bhattacharyya BJ, Lin H, Gomez CM. Skeletal muscle IP3R1 receptors amplify physiological and pathological synaptic calcium signals. J Neurosci 2011; 31:15269-83. [PMID: 22031873 PMCID: PMC3237715 DOI: 10.1523/jneurosci.3766-11.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/24/2011] [Accepted: 09/01/2011] [Indexed: 01/11/2023] Open
Abstract
Ca(2+) release from internal stores is critical for mediating both normal and pathological intracellular Ca(2+) signaling. Recent studies suggest that the inositol 1,4,5-triphosphate (IP(3)) receptor mediates Ca(2+) release from internal stores upon cholinergic activation of the neuromuscular junction (NMJ) in both physiological and pathological conditions. Here, we report that the type I IP(3) receptor (IP(3)R(1))-mediated Ca(2+) release plays a crucial role in synaptic gene expression, development, and neuromuscular transmission, as well as mediating degeneration during excessive cholinergic activation. We found that IP(3)R(1)-mediated Ca(2+) release plays a key role in early development of the NMJ, homeostatic regulation of neuromuscular transmission, and synaptic gene expression. Reducing IP(3)R(1)-mediated Ca(2+) release via siRNA knockdown or IP(3)R blockers in C2C12 cells decreased calpain activity and prevented agonist-induced acetylcholine receptor (AChR) cluster dispersal. In fully developed NMJ in adult muscle, IP(3)R(1) knockdown or blockade effectively increased synaptic strength at presynaptic and postsynaptic sites by increasing both quantal release and expression of AChR subunits and other NMJ-specific genes in a pattern resembling muscle denervation. Moreover, in two mouse models of cholinergic overactivity and NMJ Ca(2+) overload, anti-cholinesterase toxicity and the slow-channel myasthenic syndrome (SCS), IP(3)R(1) knockdown eliminated NMJ Ca(2+) overload, pathological activation of calpain and caspase proteases, and markers of DNA damage at subsynaptic nuclei, and improved both neuromuscular transmission and clinical measures of motor function. Thus, blockade or genetic silencing of muscle IP(3)R(1) may be an effective and well tolerated therapeutic strategy in SCS and other conditions of excitotoxicity or Ca(2+) overload.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/genetics
- Animals
- Boron Compounds/pharmacology
- Calcium/metabolism
- Calcium Signaling/genetics
- Calcium Signaling/physiology
- Calpain/metabolism
- Carbachol/pharmacology
- Caspase 3/metabolism
- Caspase 9/metabolism
- Cell Line, Transformed
- Cholinergic Agonists/pharmacology
- Cholinesterase Inhibitors/toxicity
- Disease Models, Animal
- Electromyography
- Electroporation/methods
- Exercise Test
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/genetics
- Green Fluorescent Proteins/genetics
- Histone Deacetylases/metabolism
- Histones/genetics
- Histones/metabolism
- In Vitro Techniques
- Inositol 1,4,5-Trisphosphate Receptors/deficiency
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/genetics
- Mice
- Mice, Transgenic
- Muscle, Skeletal/metabolism
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/pathology
- Myasthenic Syndromes, Congenital/therapy
- Neostigmine/toxicity
- Nerve Tissue Proteins/metabolism
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/physiology
- Neurotoxicity Syndromes/etiology
- Neurotoxicity Syndromes/pathology
- Neurotoxicity Syndromes/therapy
- Patch-Clamp Techniques
- RNA, Small Interfering/pharmacology
- Receptors, Cholinergic/classification
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Sciatic Nerve/physiopathology
- Time Factors
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Affiliation(s)
- Haipeng Zhu
- Department of Neurology, University of Chicago Medical Center, Chicago, Illinois 60637
| | - Bula J. Bhattacharyya
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and
| | - Hong Lin
- Departments of Neurology and Pediatrics, the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318
| | - Christopher M. Gomez
- Department of Neurology, University of Chicago Medical Center, Chicago, Illinois 60637
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11
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Bergantin LB, Figueiredo LB, Godinho RO. The lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes. J Appl Physiol (1985) 2011; 111:1710-8. [PMID: 21921242 DOI: 10.1152/japplphysiol.00586.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The molecular regulation of skeletal muscle proteolysis and the pharmacological screening of anticatabolic drugs have been addressed by measuring tyrosine release from prepubertal rat skeletal muscles, which are thin enough to allow adequate in vitro diffusion of oxygen and substrates. However, the use of muscle at accelerated prepubertal growth has limited the analysis of adult muscle proteolysis or that associated with aging and neurodegenerative diseases. Here we established the adult rat lumbrical muscle (4/hindpaw; 8/rat) as a new in situ experimental model for dynamic measurement of skeletal muscle proteolysis. By incubating lumbrical muscles attached to their individual metatarsal bones in Tyrode solution, we showed that the muscle proteolysis rate of adult and aged rats (3-4 to 24 mo old) is 45-25% of that in prepubertal animals (1 mo old), which makes questionable the usual extrapolation of proteolysis from prepubertal to adult/senile muscles. While acute mechanical injury or 1- to 7-day denervation increased tyrosine release from adult lumbrical muscle by up to 60%, it was reduced by 20-28% after 2-h incubation with β-adrenoceptor agonists, forskolin or phosphodiesterase inhibitor IBMX. Using inhibitors of 26S-proteasome (MG132), lysosome (methylamine), or calpain (E64/leupeptin) systems, we showed that ubiquitin-proteasome is accountable for 40-50% of total lumbrical proteolysis of adult, middle-aged, and aged rats. In conclusion, the lumbrical model allows the analysis of muscle proteolysis rate from prepubertal to senile rats. By permitting eight simultaneous matched measurements per rat, the new model improves similar protocols performed in paired extensor digitorum longus (EDL) muscles from prepubertal rats, optimizing the pharmacological screening of drugs for anticatabolic purposes.
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Affiliation(s)
- Leandro Bueno Bergantin
- Div. of Cellular Pharmacology, Dept. of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Três de maio, 100, São Paulo, SP, Brazil
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12
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MALOMOUZH AI, ARKHIPOVA SS, NIKOLSKY EE, VYSKOČIL F. Immunocytochemical Demonstration of M1 Muscarinic Acetylcholine Receptors at the Presynaptic and Postsynaptic Membranes of Rat Diaphragm Endplates. Physiol Res 2011; 60:185-8. [DOI: 10.33549/physiolres.932131] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
M1-muscarinic acetylcholine (ACh) receptors (M1R) were directly demonstrated immunocytochemically in electronmicroscopic images of rat diaphragm neuromuscular junctions (NMJ). Specific electron-dense granules were located at presynaptic nerve ending membranes and in the sarcolemma in the depths of postsynaptic folds. This first visualization of M1R on both sides of the NMJ is in agreement with previous pharmacological data on the regulatory role of M1R in quantal and non-quantal ACh release.
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Affiliation(s)
- A. I. MALOMOUZH
- Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, Russia
| | | | | | - F. VYSKOČIL
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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13
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Functional characterization of heterotrimeric G-proteins in rat diaphragm muscle. Respir Physiol Neurobiol 2010; 175:212-9. [PMID: 21084061 DOI: 10.1016/j.resp.2010.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 10/06/2010] [Accepted: 11/09/2010] [Indexed: 01/05/2023]
Abstract
Seven-transmembrane receptors mediate diverse skeletal muscle responses for a wide variety of stimuli, via activation of heterotrimeric G-proteins. Herein we evaluate the expression and activation of rat diaphragm or cultured skeletal muscle G-proteins using [(35)S]GTPγS. Total membrane Gα subunit content was 4-7 times higher in rat primary cultured myotubes and L6 cell line than in diaphragm (32.6±1.2fmol/mg protein) and 7-27% of them were in the active conformational state. Immunoprecipitation assay showed equal expression of diaphragm Gαs, Gαq and Gαi/o. Addition of GDP allowed the measurement of G-protein activation by different GPCR, including adrenoceptor, adenosine, melatonin and muscarinic receptors. Diaphragm denervation resulted in a marked increase in both total and active state G-protein levels. Together, the results show that [(35)S]GTPγS binding assay is a sensitive and valuable method to evaluate GPCR activity in skeletal muscle cells, which is of particular interest for pharmacological analysis of drugs with potential use in the management of respiratory muscle failure.
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14
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Moral-Naranjo MT, Montenegro MF, Muñoz-Delgado E, Campoy FJ, Vidal CJ. The levels of both lipid rafts and raft-located acetylcholinesterase dimers increase in muscle of mice with muscular dystrophy by merosin deficiency. Biochim Biophys Acta Mol Basis Dis 2010; 1802:754-64. [DOI: 10.1016/j.bbadis.2010.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/12/2010] [Accepted: 05/26/2010] [Indexed: 10/19/2022]
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15
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Paredes-Gamero EJ, Medeiros VP, Farias EHC, Justo GZ, Trindade ES, Andrade-Lopes AL, Godinho RO, de Miranda A, Ferreira AT, Tersariol ILS, Nader HB. Heparin induces rat aorta relaxation via integrin-dependent activation of muscarinic M3 receptors. Hypertension 2010; 56:713-21. [PMID: 20805441 DOI: 10.1161/hypertensionaha.110.156877] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Previous reports have shown that heparin may promote human hypotension and vascular relaxation by elevation of NO levels through unclear mechanisms. We hypothesized that endothelial muscarinic M(3) receptor activation mediates the heparin-induced vasodilation of rat aortic rings. The experiments were carried out using unfractionated heparin extracted from bovine intestinal mucosa, which elicited an endothelium and NO-dependent relaxation of aortic segments with maximal potency and efficacy (EC(50): 100±10 μmol/L; E(max): 41±3%). Atropine and 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide inhibitors reduced the heparin-dependent relaxation, indicating that M(3) muscarinic receptor is involved in this phenomenon. However, no direct binding of heparin to muscarinic receptors was observed. More importantly, studies performed using the arginine-glycine-aspartic acid peptide and 1-(1,1-dimethylethyl)-3-(1-naphthalenyl)-1H-pyrazolo[3,4-day]pyrimidin-4-amine, an Src family inhibitor, reduced by 51% and 73% the heparin-dependent relaxation, respectively, suggesting the coupling of heparin and M(3) receptor through extracellular matrix molecules and integrin. Furthermore, unfractionated heparin induced activation of focal adhesion protein kinase, Src, and paxillin. Finally, fluorescence resonance energy transfer approach confirmed the interaction of the M(3) receptor to integrin. Taken together, these data demonstrate the participation of M(3) receptor and integrin in heparin-dependent relaxation of vascular smooth muscle. These results provide new insights into the molecular mechanism and potential pharmacological action of heparin in vascular physiology.
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16
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Merlin J, Evans BA, Csikasz RI, Bengtsson T, Summers RJ, Hutchinson DS. The M3-muscarinic acetylcholine receptor stimulates glucose uptake in L6 skeletal muscle cells by a CaMKK-AMPK-dependent mechanism. Cell Signal 2010; 22:1104-13. [PMID: 20206685 DOI: 10.1016/j.cellsig.2010.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 02/23/2010] [Accepted: 03/01/2010] [Indexed: 11/15/2022]
Abstract
The role of muscarinic acetylcholine receptors (mAChRs) in regulating glucose uptake in L6 skeletal muscle cells was investigated. [(3)H]-2-Deoxyglucose uptake was increased in differentiated L6 cells by insulin, acetylcholine, oxotremorine-M and carbachol. mAChR-mediated glucose uptake was inhibited by the AMPK inhibitor Compound C. Whole cell radioligand binding using [(3)H]-N-methyl scopolamine chloride identified mAChRs in differentiated but not undifferentiated L6 cells and M(3) mAChR mRNA was detected only in differentiated cells. M(3) mAChRs are Gq-coupled, and cholinergic stimulation by the mAChR agonists acetylcholine, oxotremorine-M and carbachol increased Ca(2+) in differentiated but not undifferentiated L6 cells. This was due to muscarinic but not nicotinic activation as responses were antagonised by the muscarinic antagonist atropine but not the nicotinic antagonist tubocurarine. Western blotting showed that both carbachol and the AMPK activator AICAR increased phosphorylation of the AMPKalpha subunit at Thr172, with responses to carbachol blocked by Compound C and the CaMKK inhibitor STO609 but not by the PI3K inhibitor wortmannin. AICAR-stimulated AMPK phosphorylation was not sensitive to STO-609, confirming that this compound inhibits CaMKK but not the classical AMPK kinase LKB1. The TAK1 inhibitor (5Z)-7-oxozeaenol and the G(i) inhibitor pertussis toxin both failed to block AMPK phosphorylation in response to carbachol. Using CHO-K1 cells stably expressing each of the mAChR subtypes (M(1)-M(4)), it was determined that only the M(1) and M(3) mAChRs phosphorylate AMPK, confirming a G(q)-dependent mechanism. This study demonstrates that activation of M(3) mAChRs in L6 skeletal muscle cells stimulates glucose uptake via a CaMKK-AMPK-dependent mechanism, independent of the insulin-stimulated pathway.
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Affiliation(s)
- Jon Merlin
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Victoria, 3800, Australia
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17
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Distinct muscarinic acetylcholine receptor subtypes contribute to stability and growth, but not compensatory plasticity, of neuromuscular synapses. J Neurosci 2010; 29:14942-55. [PMID: 19940190 DOI: 10.1523/jneurosci.2276-09.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Muscarinic acetylcholine receptors (mAChRs) modulate synaptic function, but whether they influence synaptic structure remains unknown. At neuromuscular junctions (NMJs), mAChRs have been implicated in compensatory sprouting of axon terminals in paralyzed or denervated muscles. Here we used pharmacological and genetic inhibition and localization studies of mAChR subtypes at mouse NMJs to demonstrate their roles in synaptic stability and growth but not in compensatory sprouting. M(2) mAChRs were present solely in motor neurons, whereas M(1), M(3), and M(5) mAChRs were associated with Schwann cells and/or muscle fibers. Blockade of all five mAChR subtypes with atropine evoked pronounced effects, including terminal sprouting, terminal withdrawal, and muscle fiber atrophy. In contrast, methoctramine, an M(2/4)-preferring antagonist, induced terminal sprouting and terminal withdrawal, but no muscle fiber atrophy. Consistent with this observation, M(2)(-/-) but no other mAChR mutant mice exhibited spontaneous sprouting accompanied by extensive loss of parental terminal arbors. Terminal sprouting, however, seemed not to be the causative defect because partial loss of terminal branches was common even in the M(2)(-/-) NMJs without sprouting. Moreover, compensatory sprouting after paralysis or partial denervation was normal in mice deficient in M(2) or other mAChR subtypes. We also found that many NMJs of M(5)(-/-) mice were exceptionally small and reduced in proportion to the size of parental muscle fibers. These findings show that axon terminals are unstable without M(2) and that muscle fiber growth is defective without M(5). Subtype-specific muscarinic signaling provides a novel means for coordinating activity-dependent development and maintenance of the tripartite synapse.
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18
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Ghedini PC, Viel TA, Honda L, Avellar MCW, Godinho RO, Lima-Landman MTR, Lapa AJ, Souccar C. Increased expression of acetylcholine receptors in the diaphragm muscle of MDX mice. Muscle Nerve 2009; 38:1585-94. [PMID: 19016551 DOI: 10.1002/mus.21183] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The absence of dystrophin in Duchenne muscular dystrophy (DMD) and in the mutant mdx mouse causes muscle degeneration and disruption of the neuromuscular junction. Based on evidence from the denervation-like properties of these muscles, we assessed the ligand-binding constants of nicotinic acetylcholine receptors (nAChRs) and the mRNA expression of individual subunits in membrane preparations of diaphragm muscles from adult (4-month-old) and aged (20-month-old) control and mdx mice. The concentration of nAChRs as determined by the maximal specific [(125)I]-alpha-bungarotoxin binding (Bmax) in the muscle membranes did not change with aging in both animal strains. When compared to age-matched control groups, the Bmax in mdx muscles was increased by 65% in adults, and by 103% in aged mice with no alteration of toxin affinity for nAChRs. Reverse-transcription polymerase chain reaction assays showed that mRNA transcripts for the nAChR alpha1, gamma, alpha7, and beta2, but not the epsilon subunits, were more abundant in mdx than in control muscles. The results indicate increased expression of extrajunctional nAChRs in the mdx diaphragm and reflect impairment of nAChR regulation in dystrophin-deficient muscles. These observations may be related to the resistance to nondepolarizing muscle relaxants and the high sensitivity to depolarizing agents reported in DMD patients.
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Affiliation(s)
- Paulo C Ghedini
- Department of Pharmacology, Natural Products Section, Universidade Federal de São Paulo, 04044-020, Rua Três de Maio 100, São Paulo, SP, Brazil
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19
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Effects of estrogen on intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors and on acetylcholinesterase activity in rat hippocampus. Biochem Pharmacol 2008; 75:1827-34. [DOI: 10.1016/j.bcp.2008.01.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 01/24/2008] [Accepted: 01/25/2008] [Indexed: 11/20/2022]
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20
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Abstract
BACKGROUND AND PURPOSE cAMP is a key intracellular signalling molecule that regulates multiple processes of the vertebrate skeletal muscle. We have shown that cAMP can be actively pumped out from the skeletal muscle cell. Since in other tissues, cAMP efflux had been associated with extracellular generation of adenosine, in the present study we have assessed the fate of interstitial cAMP and the existence of an extracellular cAMP-adenosine signalling pathway in skeletal muscle. EXPERIMENTAL APPROACH cAMP efflux and/or its extracellular degradation were analysed by incubating rat cultured skeletal muscle with exogenous cAMP, forskolin or isoprenaline. cAMP and its metabolites were quantified by radioassay or HPLC, respectively. KEY RESULTS Incubation of cells with exogenous cAMP was followed by interstitial accumulation of 5'-AMP and adenosine, a phenomenon inhibited by selective inhibitors of ecto-phosphodiesterase (DPSPX) and ecto-nucleotidase (AMPCP). Activation of adenylyl cyclase (AC) in cultured cells with forskolin or isoprenaline increased cAMP efflux and extracellular generation of 5'-AMP and adenosine. Extracellular cAMP-adenosine pathway was also observed after direct and receptor-dependent stimulation of AC in rat extensor muscle ex vivo. These events were attenuated by probenecid, an inhibitor of ATP binding cassette family transporters. CONCLUSIONS AND IMPLICATIONS Our results show the existence of an extracellular biochemical cascade that converts cAMP into adenosine. The functional relevance of this extracellular signalling system may involve a feedback modulation of cellular response initiated by several G protein-coupled receptor ligands, amplifying cAMP influence to a paracrine mode, through its metabolite, adenosine.
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