Rapid Redistribution of Synaptic PSD-95 in the Neocortex In Vivo

@article{citeulike:935769, abstract = {Most excitatory synapses terminate on dendritic spines. Spines vary in size, and their volumes are proportional to the area of the postsynaptic density (PSD) and synaptic strength. PSD-95 is an abundant multi-domain postsynaptic scaffolding protein that clusters glutamate receptors and organizes the associated signaling complexes. PSD-95 is thought to determine the size and strength of synapses. Although spines and their synapses can persist for months in vivo, PSD-95 and other PSD proteins have shorter half-lives in vitro, on the order of hours. To probe the mechanisms underlying synapse stability, we measured the dynamics of synaptic PSD-95 clusters in vivo. Using two-photon microscopy, we imaged PSD-95 tagged with GFP in layer 2/3 dendrites in the developing (postnatal day 10\&\#8211;21) barrel cortex. A subset of PSD-95 clusters was stable for days. Using two-photon photoactivation of PSD-95 tagged with photoactivatable GFP (paGFP), we measured the time over which PSD-95 molecules were retained in individual spines. Synaptic PSD-95 turned over rapidly (median retention times \&\#964;r ~ 22\&\#8211;63 min from P10\&\#8211;P21) and exchanged with PSD-95 in neighboring spines by diffusion. PSDs therefore share a dynamic pool of PSD-95. Large PSDs in large spines captured more diffusing PSD-95 and also retained PSD-95 longer than small PSDs. Changes in the sizes of individual PSDs over days were associated with concomitant changes in PSD-95 retention times. Furthermore, retention times increased with developmental age (\&\#964;r ~ 100 min at postnatal day 70) and decreased dramatically following sensory deprivation. Our data suggest that individual PSDs compete for PSD-95 and that the kinetic interactions between PSD molecules and PSDs are tuned to regulate PSD size.}, author = {Gray, Noah W. and Weimer, Robby M. and Bureau, Ingrid and Svoboda, Karel }, citeulike-article-id = {935769}, comment = {in utero electroporation + in vivo 2P}, doi = {10.1371/journal.pbio.0040370}, journal = {PLoS Biology}, keywords = {cortical\_neurons, dendritic\_spines, fluorescent\_proteins, live\_cell\_imaging, photoactivation, postsynaptic}, month = {November}, number = {11}, pages = {e370+}, posted-at = {2006-11-10 14:24:10}, priority = {0}, title = {Rapid Redistribution of Synaptic PSD-95 in the Neocortex In Vivo}, url = {http://dx.doi.org/10.1371/journal.pbio.0040370}, volume = {4}, year = {2006} }

TY - JOUR ID - citeulike:935769 L3 - citeulike-article-id:935769 TI - Rapid Redistribution of Synaptic PSD-95 in the Neocortex In Vivo JF - PLoS Biology VL - 4 IS - 11 SP - e370 N2 - Most excitatory synapses terminate on dendritic spines. Spines vary in size, and their volumes are proportional to the area of the postsynaptic density (PSD) and synaptic strength. PSD-95 is an abundant multi-domain postsynaptic scaffolding protein that clusters glutamate receptors and organizes the associated signaling complexes. PSD-95 is thought to determine the size and strength of synapses. Although spines and their synapses can persist for months in vivo, PSD-95 and other PSD proteins have shorter half-lives in vitro, on the order of hours. To probe the mechanisms underlying synapse stability, we measured the dynamics of synaptic PSD-95 clusters in vivo. Using two-photon microscopy, we imaged PSD-95 tagged with GFP in layer 2/3 dendrites in the developing (postnatal day 10–21) barrel cortex. A subset of PSD-95 clusters was stable for days. Using two-photon photoactivation of PSD-95 tagged with photoactivatable GFP (paGFP), we measured the time over which PSD-95 molecules were retained in individual spines. Synaptic PSD-95 turned over rapidly (median retention times τr ~ 22–63 min from P10–P21) and exchanged with PSD-95 in neighboring spines by diffusion. PSDs therefore share a dynamic pool of PSD-95. Large PSDs in large spines captured more diffusing PSD-95 and also retained PSD-95 longer than small PSDs. Changes in the sizes of individual PSDs over days were associated with concomitant changes in PSD-95 retention times. Furthermore, retention times increased with developmental age (τr ~ 100 min at postnatal day 70) and decreased dramatically following sensory deprivation. Our data suggest that individual PSDs compete for PSD-95 and that the kinetic interactions between PSD molecules and PSDs are tuned to regulate PSD size. KW - cortical_neurons KW - dendritic_spines KW - fluorescent_proteins KW - live_cell_imaging KW - photoactivation KW - postsynaptic N1 - in utero electroporation + in vivo 2P AU - Gray, Noah AU - Weimer, Robby AU - Bureau, Ingrid AU - Svoboda, Karel PY - 2006/11/01/ UR - http://dx.doi.org/10.1371/journal.pbio.0040370 ER -