Modular transport of postsynaptic density-95 clusters and association with stable spine precursors during early development of cortical neurons.
The properties of filopodia and spines and their association with the postsynaptic density (PSD) protein PSD-95 were studied during early development of cultured cortical neurons using time-lapse confocal microscopy. Neurons were transfected with recombinant PSD-95 constructs fused to green fluorescent protein (GFP) for, on average, either 8 d in vitro (DIV) or 14 DIV. We find that, during 1 hr of imaging, filopodia and spines bearing PSD-95/GFP clusters are significantly more stable (i.e., do not turnover) than those lacking clusters. When present within a spine precursor, a PSD-95/GFP cluster appeared to nucleate a relatively stable structure around which filopodium-spine membranes can move. Although processes bearing clusters were generally stable, in 8 DIV neurons, we observed that a subset ( approximately 10%) of PSD-95/GFP clusters underwent rapid modular translocation between filopodia-spines and dendritic shafts. We conclude that, during early synaptic maturation, prefabricated PSD-95 clusters are trafficked in a developmentally regulated process that is associated with filopodial stabilization and synapse formation.
Prange
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Kinsmen Laboratory, Departments of Psychiatry and Physiology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
Murphy
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D000818:Animals; D001692:Biological Transport / Q000502:physiology; D022081:Cell Surface Extensions / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D000076122:Disks Large Homolog 4 Protein; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000235:genetics; D046911:Macromolecular Substances; D008565:Membrane Proteins; D018613:Microscopy, Confocal; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D021381:Protein Transport / Q000502:physiology; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012235:Rhodamines; D014162:Transfection
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D012235:Rhodamines; C033652:postsynaptic density proteins; D049452:Green Fluorescent Proteins