title: Tissue-type plasminogen activator triggers the synaptic vesicle cycle in cerebral cortical neurons.
abstract: The active zone (AZ) is a thickening of the presynaptic membrane where exocytosis takes place. Chemical synapses contain neurotransmitter-loaded synaptic vesicles (SVs) that at rest are tethered away from the synaptic release site, but after the presynaptic inflow of Ca(+2) elicited by an action potential translocate to the AZ to release their neurotransmitter load. We report that tissue-type plasminogen activator (tPA) is stored outside the AZ of cerebral cortical neurons, either intermixed with small clear-core vesicles or in direct contact with the presynaptic membrane. We found that cerebral ischemia-induced release of neuronal tPA, or treatment with recombinant tPA, recruits the cytoskeletal protein βII-spectrin to the AZ and promotes the binding of SVs to βII-spectrin, enlarging the population of SVs in proximity to the synaptic release site. This effect does not require the generation of plasmin and is followed by the recruitment of voltage gated calcium channels (VGCC) to the presynaptic terminal that leads to Ca(+2)-dependent synapsin I phosphorylation, freeing SVs to translocate to the AZ to deliver their neurotransmitter load. Our studies indicate that tPA activates the SV cycle and induces the structural and functional changes in the synapse that are required for successful neurotransmission.
authors.affiliation: Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
authors.affiliation: Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Torre
authors.affiliation: Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: David
authors.initials: D
authors.lastname: Cuellar-Giraldo
authors.affiliation: Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Lihong
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Apkarian Integrated Electron Microscopy Core, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.affiliation: Department of Anesthesiology, Veterans Affairs Medical Center, Atlanta, Georgia, USA.|Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Edyta K
authors.initials: EK
authors.lastname: Bichler
authors.affiliation: Department of Anesthesiology, Veterans Affairs Medical Center, Atlanta, Georgia, USA.|Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: García
authors.affiliation: Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia, USA.|Department of Neurology, Veterans Affairs Medical Center, Atlanta, Georgia, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Yepes
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002545:Brain Ischemia / Q000473:pathology; D015220:Calcium Channels / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology* / Q000187:drug effects*; D005089:Exocytosis / Q000187:drug effects; D005341:Fibrinolysin / Q000096:biosynthesis; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D017729:Presynaptic Terminals / Q000187:drug effects; D040901:Proteomics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013049:Spectrin / Q000096:biosynthesis; D016704:Synapsins / Q000378:metabolism; D013572:Synaptic Vesicles / Q000187:drug effects*; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*
chemical_list: D015220:Calcium Channels; D016704:Synapsins; D013049:Spectrin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin