title: Protein phosphatase-1M and Rho-kinase affect exocytosis from cortical synaptosomes and influence neurotransmission at a glutamatergic giant synapse of the rat auditory system.
abstract: Protein phosphatase-1M (PP1M, myosin phosphatase) consists of a PP1 catalytic subunit (PP1c) and the myosin phosphatase target subunit-1 (MYPT1). RhoA-activated kinase (ROK) regulates PP1M via inhibitory phosphorylation of MYPT1. Using multidisciplinary approaches, we have studied the roles of PP1M and ROK in neurotransmission. Electron microscopy demonstrated the presence of MYPT1 and ROK in both pre- and post-synaptic terminals. Tautomycetin (TMC), a PP1-specific inhibitor, decreased the depolarization-induced exocytosis from cortical synaptosomes. trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride, a ROK-specific inhibitor, had the opposite effect. Mass spectrometry analysis identified several MYPT1-bound synaptosomal proteins, of which interactions of synapsin-I, syntaxin-1, calcineurin-A subunit, and Ca(2+) /calmodulin-dependent kinase II with MYPT1 were confirmed. In intact synaptosomes, TMC increased, whereas Y27632 decreased the phosphorylation levels of MYPT1(Thr696) , myosin-II light chain(Ser19) , synapsin-I(Ser9) , and syntaxin-1(Ser14) , indicating that PP1M and ROK influence their phosphorylation status. Confocal microscopy indicated that MYPT1 and ROK are present in the rat ventral cochlear nucleus both pre- and post-synaptically. Analysis of the neurotransmission in an auditory glutamatergic giant synapse demonstrated that PP1M and ROK affect neurotransmission via both pre- and post-synaptic mechanisms. Our data suggest that both PP1M and ROK influence synaptic transmission, but further studies are needed to give a full account of their mechanism of action.
authors: Department of Medical Chemistry and Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
authors: Beáta
authors: B
authors: Lontay
authors: Balázs
authors: B
authors: Pál
authors: Zoltán
authors: Z
authors: Serfőző
authors: Áron
authors: Á
authors: Kőszeghy
authors: Géza
authors: G
authors: Szücs
authors: Zoltán
authors: Z
authors: Rusznák
authors: Ferenc
authors: F
authors: Erdődi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D024722:Cardiac Myosins / Q000378:metabolism; D002540:Cerebral Cortex / Q000648:ultrastructure*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005089:Exocytosis / Q000502:physiology*; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D008297:Male; D013058:Mass Spectrometry; D046529:Microscopy, Electron, Transmission; D018994:Myosin Light Chains / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011485:Protein Binding / Q000187:drug effects; D054645:Protein Phosphatase 1 / Q000378:metabolism* / Q000648:ultrastructure; D050765:Qa-SNARE Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D016704:Synapsins / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D013574:Synaptosomes / Q000378:metabolism* / Q000648:ultrastructure; D013912:Threonine / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004791:Enzyme Inhibitors; D018994:Myosin Light Chains; D050765:Qa-SNARE Proteins; D016704:Synapsins; C107184:myosin light chain 2; D013912:Threonine; D018698:Glutamic Acid; D012694:Serine; D054460:rho-Associated Kinases; D054645:Protein Phosphatase 1; D024722:Cardiac Myosins; D002118:Calcium