联合的PSD-95活体皮层飞秒激光器快速再分配技术

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 signa领 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 1021) 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 sr ; 2263 min from P10P21) and exchanged with PSD-
95 in neioring 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 (sr ; 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. 飞秒激光器