title: A distinct trans-Golgi network subcompartment for sorting of synaptic and granule proteins in neurons and neuroendocrine cells.
abstract: Golgi-to-plasma-membrane trafficking of synaptic-like microvesicle (SLMV) proteins, vesicular acetylcholine transporter (VAChT) and synaptophysin (SYN), and a large dense-core vesicle (LDCV) protein, chromogranin A (CgA), was investigated in undifferentiated neuroendocrine PC12 cells. Live cell imaging and 20°C block-release experiments showed that VAChT-GFP, SYN-GFP and CgA-RFP specifically and transiently cohabitated in a distinct sorting compartment during cold block and then separated into synaptic protein transport vesicles (SPTVs) and LDCVs, after release from temperature block. We found that in this trans-Golgi subcompartment there was colocalization of SPTV and LDCV proteins, most significantly with VAMP4 and Golgin97, and to some degree with TGN46, but not at all with TGN38. Moreover, some SNAP25 and VAMP2, two subunits of the exocytic machinery, were also recruited onto this compartment. Thus, in neuroendocrine cells, synaptic vesicle and LDCV proteins converge briefly in a distinct trans-Golgi network subcompartment before sorting into SPTVs and LDCVs, ultimately for delivery to the plasma membrane. This specialized sorting compartment from which SPTVs and LDCVs bud might facilitate the acquisition of common exocytic machinery needed on the membranes of these vesicles.
authors.affiliation: Section on Cellular Neurobiology, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Park
authors.forename: Marjorie C
authors.initials: MC
authors.lastname: Gondré-Lewis
authors.forename: Lee E
authors.initials: LE
authors.lastname: Eiden
authors.forename: Y Peng
authors.initials: YP
authors.lastname: Loh
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D053379:Chromogranin A / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D003594:Cytoplasmic Granules / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D055099:Neuroendocrine Cells / Q000166:cytology* / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D016716:PC12 Cells; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism*; D016708:Synaptophysin / Q000235:genetics / Q000378:metabolism; D050494:Vesicular Acetylcholine Transport Proteins / Q000235:genetics / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure*
chemical_list: D053379:Chromogranin A; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; D016708:Synaptophysin; D050494:Vesicular Acetylcholine Transport Proteins