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Di Bona A, Vita V, Costantini I, Zaglia T. Towards a clearer view of sympathetic innervation of cardiac and skeletal muscles. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 154:80-93. [DOI: 10.1016/j.pbiomolbio.2019.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/02/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023]
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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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Rudolf R, Khan MM, Lustrino D, Labeit S, Kettelhut IC, Navegantes LCC. Alterations of cAMP-dependent signaling in dystrophic skeletal muscle. Front Physiol 2013; 4:290. [PMID: 24146652 PMCID: PMC3797997 DOI: 10.3389/fphys.2013.00290] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 09/24/2013] [Indexed: 12/19/2022] Open
Abstract
Autonomic regulation processes in striated muscles are largely mediated by cAMP/PKA-signaling. In order to achieve specificity of signaling its spatial-temporal compartmentation plays a critical role. We discuss here how specificity of cAMP/PKA-signaling can be achieved in skeletal muscle by spatio-temporal compartmentation. While a microdomain containing PKA type I in the region of the neuromuscular junction (NMJ) is important for postsynaptic, activity-dependent stabilization of the nicotinic acetylcholine receptor (AChR), PKA type I and II microdomains in the sarcomeric part of skeletal muscle are likely to play different roles, including the regulation of muscle homeostasis. These microdomains are due to specific A-kinase anchoring proteins, like rapsyn and myospryn. Importantly, recent evidence indicates that compartmentation of the cAMP/PKA-dependent signaling pathway and pharmacological activation of cAMP production are aberrant in different skeletal muscles disorders. Thus, we discuss here their potential as targets for palliative treatment of certain forms of dystrophy and myasthenia. Under physiological conditions, the neuropeptide, α-calcitonin-related peptide, as well as catecholamines are the most-mentioned natural triggers for activating cAMP/PKA signaling in skeletal muscle. While the precise domains and functions of these first messengers are still under investigation, agonists of β2-adrenoceptors clearly exhibit anabolic activity under normal conditions and reduce protein degradation during atrophic periods. Past and recent studies suggest direct sympathetic innervation of skeletal muscle fibers. In summary, the organization and roles of cAMP-dependent signaling in skeletal muscle are increasingly understood, revealing crucial functions in processes like nerve-muscle interaction and muscle trophicity.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim , Mannheim, Germany ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , Eggenstein-Leopoldshafen, Germany
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Jia M, Li MX, Fields RD, Nelson PG. Extracellular ATP in activity-dependent remodeling of the neuromuscular junction. Dev Neurobiol 2007; 67:924-32. [PMID: 17506503 DOI: 10.1002/dneu.20402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Electrical activity during early development affects the development and maintenance of synapses (Spitzer [2006]: Nature 4447:707-712), but the intercellular signals regulating maintenance of synapses are not well identified. At the neuromuscular junction, adenosine 5-triphosphate (ATP) is coreleased with acetylcholine at activated nerve terminals to modulate synaptic function. Here we use cocultured mouse motor neurons and muscle cells in a three-compartment cell culture chamber to test whether endogenously released ATP plays a role in activity-dependent maintenance of neuromuscular synapses. The results suggest that ATP release at the synapse counters the negative effect of electrical activity, thus stabilizing activated synapses. Confirming our previous work (Li et al. [2001]: Nat Neurosci 4:871-872), we found that in doubly innervated muscles, electrical stimulation induced heterosynaptic downregulation of the nonstimulated convergent input to the muscle fiber with no or little change of the stimulated inputs. However, in preparations that were stimulated in the presence of apyrase, an enzyme that degrades extracellular ATP, synapse downregulation of stimulated inputs was substantial and significant, and end plate potentials were reduced. Apyrase treatment for 20 h in the absence of stimulation did result in moderate diminution, but this was prevented by blocking spontaneous neural activity with tetrodotoxin. The P2 receptor blocker, suramin, also induced activity-dependent synapse diminution. The decrease in synaptic efficacy produced by prolonged stimulation in the presence of apyrase persisted for greater than 20 h, consistent with a developmental time-course and distinct from the rapid neuromodulatory actions of ATP that have been demonstrated by others. We conclude that extracellular ATP promotes stabilization of the neuromuscular junction and may play a role in activity-dependent synaptic modification during development.
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Affiliation(s)
- Min Jia
- National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, Maryland 20892, USA.
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Kuzirian AM, Epstein HT, Gagliardi CJ, Nelson TJ, Sakakibara M, Taylor C, Scioletti AB, Alkon DL. Bryostatin enhancement of memory in Hermissenda. THE BIOLOGICAL BULLETIN 2006; 210:201-14. [PMID: 16801495 DOI: 10.2307/4134558] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Bryostatin, a potent agonist of protein kinase C (PKC), when administered to Hermissenda was found to affect acquisition of an associative learning paradigm. Low bryostatin concentrations (0.1 to 0.5 ng/ml) enhanced memory acquisition, while concentrations higher than 1.0 ng/ml down-regulated the pathway and no recall of the associative training was exhibited. The extent of enhancement depended upon the conditioning regime used and the memory stage normally fostered by that regime. The effects of two training events (TEs) with paired conditioned and unconditioned stimuli, which standardly evoked only short-term memory (STM) lasting 7 min, were--when bryostatin was added concurrently--enhanced to a long-term memory (LTM) that lasted about 20 h. The effects of both 4- and 6-paired TEs (which by themselves did not generate LTM), were also enhanced by bryostatin to induce a consolidated memory (CM) that lasted at least 5 days. The standard positive 9-TE regime typically produced a CM lasting at least 6 days. Low concentrations of bryostatin (<0.5 ng/ml) elicited no demonstrable enhancement of CM from 9-TEs. However, animals exposed to bryostatin concentrations higher than 1.0 ng/ml exhibited no behavioral learning. Sharp-electrode intracellular recordings of type-B photoreceptors in the eyes from animals conditioned in vivo with bryostatin revealed changes in input resistance and an enhanced long-lasting depolarization (LLD) in response to light. Likewise, quantitative immunocytochemical measurements using an antibody specific for the PKC-activated Ca2+/GTP-binding protein calexcitin showed enhanced antibody labeling with bryostatin. Animals exposed to the PKC inhibitor bisindolylmaleimide-XI (Ro-32-0432) administered by immersion prior to 9-TE conditioning showed no training-induced changes with or without bryostatin exposure. However, if animals received bryostatin before Ro-32, the enhanced acquisition and demonstrated recall still occurred. Therefore, pathways responsible for the enhancement effects induced by bryostatin were putatively mediated by PKC. Overall, the data indicated that PKC activation occurred and calexcitin levels were raised during the acquisition phases of associative conditioning and memory initiation, and subsequently returned to baseline levels within 24 and 48 h, respectively. Therefore, the protracted recall measured by the testing regime used was probably due to bryostatin-induced changes during the acquisition and facilitated storage of memory, and not necessarily to enhanced recall of the stored memory when tested many days after training.
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Affiliation(s)
- A M Kuzirian
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.
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Yang LX, Nelson PG. Glia cell line-derived neurotrophic factor regulates the distribution of acetylcholine receptors in mouse primary skeletal muscle cells. Neuroscience 2005; 128:497-509. [PMID: 15381279 DOI: 10.1016/j.neuroscience.2004.06.067] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2004] [Indexed: 11/17/2022]
Abstract
It was recently reported that glia cell line-derived neurotrophic factor (GDNF) facilitates presynaptic axonal growth and neurotransmitter release at neuromuscular synapses. Little is known, however, whether GDNF can also act on the postsynaptic apparatus and its underlying mechanisms. Using biochemical cold blocking of existing membrane acetylcholine receptors (AchRs) and biotinylation of newly inserted receptors we demonstrate that GDNF increases the insertion of AChRs into the surface membrane of mouse primary cultured muscle cells and that this does not require protein synthesis. Quantitative data from double-label imaging indicate that GDNF induces a quick and substantial increase in AchR insertion as well as lateral movement into AchR aggregates, relative to a weak effect on reducing the loss of receptors from pre-existing AchR aggregates, which in contrast to the effect of PMA. These effects occur in both innervated and un-innervated muscles, and GDNF affects nerve-muscle co-cultures more than it affects muscle-only cultures. Neurturin, another member of GDNF-family ligands has similar effects on AchRs as GDNF but the unrelated growth factor, EGF does not. Studies on protein phosphorylation and specific inhibitors of cell signal transduction indicate that GDNF function is mediated by receptor GFRalpha1 and involves MAPK, cAMP/cAMP responsive element-binding factor and Src kinase activities. GDNF may signal through c-Ret as well as NCAM-140 pathways since both the signaling receptors are expressed in the neuromuscular junction (NMJ). These data suggest that GDNF is an autocrine regulator of NMJ to promote the insertion and stabilization of postsynaptic AchRs. In vivo, GDNF may function as a synaptotrophic modulator for both pre- and postsynaptic differentiation to strengthen the functional and structural connections between nerve and muscle, and contribute to the synaptogenesis and plasticity of neuromuscular synapses.
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Affiliation(s)
- L-X Yang
- Section on Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bldg 49, Bethesda, MD 20892, USA.
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Li MX, Jia M, Yang LX, Jiang H, Lanuza MA, Gonzalez CM, Nelson PG. The role of the theta isoform of protein kinase C (PKC) in activity-dependent synapse elimination: evidence from the PKC theta knock-out mouse in vivo and in vitro. J Neurosci 2004; 24:3762-9. [PMID: 15084656 PMCID: PMC6729339 DOI: 10.1523/jneurosci.3930-03.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
PKC plays a critical role in competitive activity-dependent synapse modification at the neuromuscular synapse in vitro and in vivo. This action involves a reduction of the strength of inactive inputs to muscle cells that are activated by other inputs. A decrease of postsynaptic responsiveness and a loss of postsynaptic acetyl choline receptors account for the heterosynaptic loss in vitro. The loss is not seen in preparations in which PKC has been blocked pharmacologically. Here, we show that the loss does not occur in in vitro preparations made from animals genetically modified to lack the theta isoform of PKC. Synapse elimination in the newborn period in vivo is delayed but is eventually expressed in knock-out animals. PKC-dependent synapse reduction is suppressed in heterologous cultures combining normal nerve and PKC theta-deficient muscle, as might be expected from the postsynaptic locus of the changes that underlie the activity-dependent plasticity. Preparations in which PKC theta-deficient neurons innervated normal muscle also exhibited a marked deficit in PKC-deficient synapse reduction. The presynaptic action of PKC theta implied by this observation is blocked by TTX, and we propose that activity-related synapse strengthening is decreased by presynaptic PKC theta. Thus, PKC theta in both presynaptic and postsynaptic elements plays a critical role in activity-dependent synapse modulation and loss. We provide a model for activity-dependent synapse loss incorporating these findings.
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Affiliation(s)
- Min-Xu Li
- Section on Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutesof Health, Bethesda, Maryland 20892, USA.
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Abstract
The Hebb synapse, in which the strength of synapses is affected by activity in presynaptic and postsynaptic nerve cells, is a widely used model for developmental and learning-related neuroplasticity. Presynaptic and postsynaptic firing that is correlated in time is postulated to increase synaptic strength while activity in presynaptic and postsynaptic neurons that is not correlated results in weakening. The authors describe a cell biologic, mechanistic model for activity-dependent modification of synapse strength that selectively weakens inactive inputs to activated targets. Differentially localized protein kinase A and protein kinase C molecules are activated by spike and synaptic activity. Subsequent kinase-specific phosphorylation and stabilization or destabilization of synaptic receptors are molecular and cell biologic substrates of the Hebb synapse.
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Affiliation(s)
- Phillip G Nelson
- Section on Neurobiology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, Maryland 20892, USA.
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