title: Assembly of active zone precursor vesicles: obligatory trafficking of presynaptic cytomatrix proteins Bassoon and Piccolo via a trans-Golgi compartment.
abstract: Neurotransmitter release from presynaptic nerve terminals is restricted to specialized areas of the plasma membrane, so-called active zones. Active zones are characterized by a network of cytoplasmic scaffolding proteins involved in active zone generation and synaptic transmission. To analyze the modes of biogenesis of this cytomatrix, we asked how Bassoon and Piccolo, two prototypic active zone cytomatrix molecules, are delivered to nascent synapses. Although these proteins may be transported via vesicles, little is known about the importance of a vesicular pathway and about molecular determinants of cytomatrix molecule trafficking. We found that Bassoon and Piccolo co-localize with markers of the trans-Golgi network in cultured neurons. Impairing vesicle exit from the Golgi complex, either using brefeldin A, recombinant proteins, or a low temperature block, prevented transport of Bassoon out of the soma. Deleting a newly identified Golgi-binding region of Bassoon impaired subcellular targeting of recombinant Bassoon. Overexpressing this region to specifically block Golgi binding of the endogenous protein reduced the concentration of Bassoon at synapses. These results suggest that, during the period of bulk synaptogenesis, a primordial cytomatrix assembles in a trans-Golgi compartment. They further indicate that transport via Golgi-derived vesicles is essential for delivery of cytomatrix proteins to the synapse. Paradigmatically this establishes Golgi transit as an obligatory step for subcellular trafficking of distinct cytoplasmic scaffolding proteins.
authors.affiliation: Leibniz Institute for Neurobiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dresbach
authors.forename: Viviana
authors.initials: V
authors.lastname: Torres
authors.forename: Nina
authors.initials: N
authors.lastname: Wittenmayer
authors.forename: Wilko D
authors.initials: WD
authors.lastname: Altrock
authors.forename: Pedro
authors.initials: P
authors.lastname: Zamorano
authors.forename: Werner
authors.initials: W
authors.lastname: Zuschratter
authors.forename: Ralph
authors.initials: R
authors.lastname: Nawrotzki
authors.forename: Noam E
authors.initials: NE
authors.lastname: Ziv
authors.forename: Craig C
authors.initials: CC
authors.lastname: Garner
authors.forename: Eckart D
authors.initials: ED
authors.lastname: Gundelfinger
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D020126:Brefeldin A / Q000494:pharmacology; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism*; D021601:trans-Golgi Network / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D015415:Biomarkers; C113688:Bsn protein, rat; D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; C405514:Pclo protein, rat; D011500:Protein Synthesis Inhibitors; D011993:Recombinant Fusion Proteins; D020126:Brefeldin A