, JBC Papers in Press, September 13, 2013, DOI 10.1074/jbc.M113.Jose J. Ferrero
, JBC Papers in Press, September 13, 2013, DOI 10.1074/jbc.M113.Jose J. Ferrero1, Ana M. Alvarez, Jorge Ram ez-Franco, Mar C. MEK1 Molecular Weight Godino, David BartolomMart , Carolina Aguado Magdalena Torres, Rafael Luj Francisco Ciruela and JosS chez-Prieto2 From the Departamento de Bioqu ica, Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain, the Departamento de Ciencias M icas, Facultad de Medicina, Universidad de Castilla-La Mancha, Campus Biosanitario, 02006 Albacete, Spain, plus the nitat de Farmacologia, Facultat de Medicina, Departament de Patologia i Terap tica Experimental, IDIBELL, Universitat de Barcelona, L’Hospitalet de Llobregat, 08907 Barcelona, SpainBackground: G protein-coupled receptors generating cAMP at nerve terminals modulate neurotransmitter release. Final results: -Adrenergic receptor enhances glutamate K-Ras manufacturer release via Epac protein activation and Munc13-1 translocation at cerebrocortical nerve terminals. Conclusion: Protein kinase A-independent signaling pathways triggered by -adrenergic receptors handle presynaptic function. Significance: -Adrenergic receptors target presynaptic release machinery. The adenylyl cyclase activator forskolin facilitates synaptic transmission presynaptically via cAMP-dependent protein kinase (PKA). Additionally, cAMP also increases glutamate release by way of PKA-independent mechanisms, although the downstream presynaptic targets stay largely unknown. Here, we describe the isolation of a PKA-independent element of glutamate release in cerebrocortical nerve terminals right after blocking Na channels with tetrodotoxin. We discovered that 8-pCPT-2 -OMe-cAMP, a specific activator on the exchange protein directly activated by cAMP (Epac), mimicked and occluded forskolininduced potentiation of glutamate release. This Epac-mediated improve in glutamate release was dependent on phospholipase C, and it elevated the hydrolysis of phosphatidylinositol four,5bisphosphate. Furthermore, the potentiation of glutamate release by Epac was independent of protein kinase C, even though it was attenuated by the diacylglycerol-binding site antagonist calphostin C. Epac activation translocated the active zone protein Munc13-1 from soluble to particulate fractions; it enhanced the association in between Rab3A and RIM1 and redistributed synaptic vesicles closer for the presynaptic membrane. Furthermore, these responses were mimicked by the -adrenergic receptor ( AR) agonist isoproterenol, constant using the immunoelectron microscopy and immunocytochemical information demonstrating presynaptic expression of ARs in a subset of glutamatergic synapses within the cerebral cortex. According to these findings, we conclude that ARs couple to a cAMP/Epac/PLC/Munc13/Rab3/ RIM-dependent pathway to enhance glutamate release at cerebrocortical nerve terminals.The adenylyl cyclase activator forskolin presynaptically facilitates synaptic transmission and glutamate release at numerous synapses (1). Many studies have located that this presynaptic facilitation is dependent on the activation with the cAMP-dependent protein kinase (PKA) (1, two, four, 8), consistent using the acquiring that lots of proteins of the release machinery are targets of PKA, like rabphilin-3 (10), synapsins (11), Rab3-interacting molecule (RIM)three (124), and Snapin (15). A PKA-dependent element of release has been identified in studies of evoked synaptic transmission responses (1, four), because Na , Ca2 -dependent K and Ca2 channels are also PKA targets (16 1). However, forskolin-induced facilitation of gluta.