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Involvement of the Voltage-Gated Calcium Channels L- P/Q- and N-Types in Synapse Elimination During Neuromuscular Junction Development. Mol Neurobiol 2022; 59:4044-4064. [PMID: 35474562 PMCID: PMC9167222 DOI: 10.1007/s12035-022-02818-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 03/22/2022] [Indexed: 10/26/2022]
Abstract
During the nervous system development, synapses are initially overproduced. In the neuromuscular junction (NMJ) however, competition between several motor nerve terminals and the synapses they made ends with the maturation of only one axon. The competitive signaling between axons is mediated by the differential activity-dependent release of the neurotransmitter ACh, co-transmitters, and neurotrophic factors. A multiple metabotropic receptor-driven downstream balance between PKA and PKC isoforms modulates the phosphorylation of targets involved in transmitter release and nerve terminal stability. Previously, we observed in the weakest endings on the polyinnervated NMJ that M1 mAChR receptors reduce ACh release through the PKC pathway coupled to an excess of Ca2+ inflow through P/Q- N- and L-type voltage-gated calcium channels (VGCC). This signaling would contribute to the elimination of this nerve terminal. Here, we investigate the involvement of the P/Q-, N-, and L-subtype channels in transgenic B6.Cg-Tg (Thy1-YFP)16-Jrs/J mice during synapse elimination. Then, the axon number and postsynaptic receptor cluster morphologic maturation were evaluated. The results show that both L- and P/Q-type VGCC (but not the N-type) are equally involved in synapse elimination. Their normal function favors supernumerary axonal loss by jointly enhancing intracellular calcium [Ca2+]i. The block of these VGCCs or [Ca2+]i i sequestration results in the same delay of axonal loss as the cPKCβI and nPKCε isoform block or PKA activation. The specific block of the muscle cell's contraction with μ-conotoxin GIIIB also delays synapse maturation, and thus, a retrograde influence from the postsynaptic site regulating the presynaptic CaV1.3 may contribute to the synapse elimination.
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Opposed Actions of PKA Isozymes (RI and RII) and PKC Isoforms (cPKCβI and nPKCε) in Neuromuscular Developmental Synapse Elimination. Cells 2019; 8:cells8111304. [PMID: 31652775 PMCID: PMC6912401 DOI: 10.3390/cells8111304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/10/2019] [Accepted: 10/19/2019] [Indexed: 02/06/2023] Open
Abstract
Background: During neuromuscular junction (NMJ) development, synapses are produced in excess. By sensing the activity-dependent release of ACh, adenosine, and neurotrophins, presynaptic receptors prompt axonal competition and loss of the unnecessary axons. The receptor action is mediated by synergistic and antagonistic relations when they couple to downstream kinases (mainly protein kinases A and C (PKA and PKC)), which phosphorylate targets involved in axonal disconnection. Here, we directly investigated the involvement of PKA subunits and PKC isoforms in synapse elimination. Methods: Selective PKA and PKC peptide modulators were applied daily to the Levator auris longus (LAL) muscle surface of P5–P8 transgenic B6.Cg-Tg (Thy1-YFP) 16 Jrs/J (and also C57BL/6J) mice, and the number of axons and the postsynaptic receptor cluster morphology were evaluated in P9 NMJ. Results: PKA (PKA-I and PKA-II isozymes) acts at the pre- and postsynaptic sites to delay both axonal elimination and nAChR cluster differentiation, PKC activity promotes both axonal loss (a cPKCβI and nPKCε isoform action), and postsynaptic nAChR cluster maturation (a possible role for PKCθ). Moreover, PKC-induced changes in axon number indirectly influence postsynaptic maturation. Conclusions: PKC and PKA have opposed actions, which suggests that changes in the balance of these kinases may play a major role in the mechanism of developmental synapse elimination.
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Lanuza MA, Tomàs J, Garcia N, Cilleros-Mañé V, Just-Borràs L, Tomàs M. Axonal competition and synapse elimination during neuromuscular junction development. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Tomàs J, Garcia N, Lanuza MA, Santafé MM, Tomàs M, Nadal L, Hurtado E, Simó-Ollé A, Cilleros-Mañé V, Just-Borràs L. Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways. Front Pharmacol 2018; 9:397. [PMID: 29740322 PMCID: PMC5928480 DOI: 10.3389/fphar.2018.00397] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 04/05/2018] [Indexed: 12/30/2022] Open
Abstract
In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR) in the mammalian neuromuscular junction (NMJ). Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells) cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally). These observations underlie the relevance of AR in the NMJ function.
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Affiliation(s)
- Josep Tomàs
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Maria A Lanuza
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Manel M Santafé
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Laura Nadal
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Erica Hurtado
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Anna Simó-Ollé
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain
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