title: The dynamics of SAP90/PSD-95 recruitment to new synaptic junctions.
abstract: SAP90/PSD-95 is thought to be a central organizer of the glutamatergic synapse postsynaptic reception apparatus. To assess its potential role during glutamatergic synapse formation, we used GFP-tagged SAP90/PSD-95, time lapse confocal microscopy, and cultured hippocampal neurons to determine its dynamic recruitment into new synaptic junctions. We report that new SAP90/PSD-95 clusters first appeared at new axodendritic contact sites within 20-60 min of contact establishment. SAP90/PSD-95 clustering was rapid, with kinetics that fit a single exponential with a mean time constant of approximately 23 min. Most new SAP90/PSD-95 clusters were found juxtaposed to functional presynaptic boutons as determined by labeling with FM 4-64. No evidence was found for the existence of discrete transport particles similar to those previously reported to mediate presynaptic active zone cytoskeleton assembly. Instead, we found that SAP90/PSD-95 is recruited to nascent synapses from a diffuse dendritic cytoplasmic pool. Our findings show that SAP90/PSD-95 is recruited to nascent synaptic junctions early during the assembly process and indicate that its assimilation is fundamentally different from that of presynaptic active zone components.
authors.affiliation: Rappaport Institute, Technion, Haifa, Israel.
authors.forename: T
authors.initials: T
authors.lastname: Bresler
authors.forename: Y
authors.initials: Y
authors.lastname: Ramati
authors.forename: P L
authors.initials: PL
authors.lastname: Zamorano
authors.forename: R
authors.initials: R
authors.lastname: Zhai
authors.forename: C C
authors.initials: CC
authors.lastname: Garner
authors.forename: N E
authors.initials: NE
authors.lastname: Ziv
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002450:Cell Communication / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism / Q000648:ultrastructure; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D018698:Glutamic Acid / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D007150:Immunohistochemistry; D007202:Indicators and Reagents / Q000493:pharmacokinetics; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D008164:Luminescent Proteins / Q000493:pharmacokinetics; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D017711:Nonlinear Dynamics; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000074407:SAP90-PSD95 Associated Proteins; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D022161:Transport Vesicles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D007202:Indicators and Reagents; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D000074407:SAP90-PSD95 Associated Proteins; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid