title: The novel protein kinase C epsilon isoform at the adult neuromuscular synapse: location, regulation by synaptic activity-dependent muscle contraction through TrkB signaling and coupling to ACh release.
abstract: BACKGROUND
  Protein kinase C (PKC) regulates a variety of neural functions, including neurotransmitter release. Although various PKC isoforms can be expressed at the synaptic sites and specific cell distribution may contribute to their functional diversity, little is known about the isoform-specific functions of PKCs in neuromuscular synapse. The present study is designed to examine the location of the novel isoform nPKCε at the neuromuscular junction (NMJ), their synaptic activity-related expression changes, its regulation by muscle contraction, and their possible involvement in acetylcholine release.
  
  
  RESULTS
  We use immunohistochemistry and confocal microscopy to demonstrate that the novel isoform nPKCε is exclusively located in the motor nerve terminals of the adult rat NMJ. We also report that electrical stimulation of synaptic inputs to the skeletal muscle significantly increased the amount of nPKCε isoform as well as its phosphorylated form in the synaptic membrane, and muscle contraction is necessary for these nPKCε expression changes. The results also demonstrate that synaptic activity-induced muscle contraction promotes changes in presynaptic nPKCε through the brain-derived neurotrophic factor (BDNF)-mediated tyrosine kinase receptor B (TrkB) signaling. Moreover, nPKCε activity results in phosphorylation of the substrate MARCKS involved in actin cytoskeleton remodeling and related with neurotransmission. Finally, blocking nPKCε with a nPKCε-specific translocation inhibitor peptide (εV1-2) strongly reduces phorbol ester-induced ACh release potentiation, which further indicates that nPKCε is involved in neurotransmission.
  
  
  CONCLUSIONS
  Together, these results provide a mechanistic insight into how synaptic activity-induced muscle contraction could regulate the presynaptic action of the nPKCε isoform and suggest that muscle contraction is an important regulatory step in TrkB signaling at the NMJ.
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. teresa.obis@gmail.com.
authors.forename: Teresa
authors.initials: T
authors.lastname: Obis
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. nbesal@yahoo.es.
authors.forename: Núria
authors.initials: N
authors.lastname: Besalduch
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. erica.hurtado@urv.cat.
authors.forename: Erica
authors.initials: E
authors.lastname: Hurtado
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. lauranadalm@gmail.com.
authors.forename: Laura
authors.initials: L
authors.lastname: Nadal
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. manuel.santafe@urv.cat.
authors.forename: Manel M
authors.initials: MM
authors.lastname: Santafe
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. ngs@fmcs.urv.es.
authors.forename: Neus
authors.initials: N
authors.lastname: Garcia
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. marta.tomas@urv.cat.
authors.forename: Marta
authors.initials: M
authors.lastname: Tomàs
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. merce18pl@hotmail.com.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Priego
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. mariaangel.lanuza@urv.cat.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Lanuza
authors.affiliation: Unitat d'Histologia i Neurobiologia (UHN). Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain. josepmaria.tomas@urv.cat.
authors.forename: Josep
authors.initials: J
authors.lastname: Tomàs
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D055724:Electrophysiological Phenomena / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009469:Neuromuscular Junction / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013569:Synapses / Q000187:drug effects / Q000201:enzymology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D020813:Receptor, trkB; D051744:Protein Kinase C-epsilon; D000109:Acetylcholine; D013755:Tetradecanoylphorbol Acetate