Reese Thomas S.

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Reese
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Thomas S.
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Subject: Postsynaptic density ×

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  • Article
    Distribution of postsynaptic density (PSD)-95 and Ca2+/calmodulin-dependent protein kinase II at the PSD
    (Society for Neuroscience, 2003-12-03) Petersen, Jennifer D. ; Chen, Xiaobing ; Vinade, Lucia ; Dosemeci, Ayse ; Lisman, John E. ; Reese, Thomas S.
    Postsynaptic densities (PSDs) contain proteins that regulate synaptic transmission. We determined the positions of calcium/calmodulin-dependent protein kinase II (CaMKII) and PSD-95 within the three-dimensional structure of isolated PSDs using immunogold labeling, rotary shadowing, and electron microscopic tomography. The results show that all PSDs contain a central mesh immediately underlying the postsynaptic membrane. Label for PSD-95 is found on both the cytoplasmic and cleft sides of this mesh, averaging 12 nm from the cleft side. All PSDs label for PSD-95. The properties of CaMKII labeling are quite different. Label is virtually absent on the cleft sides of PSDs, but can be heavy on the cytoplasmic side at a mean distance of 25 nm from the cleft. In tomograms, CaMKII holoenzymes can be visualized directly, appearing as labeled, tower-like structures reflecting the 20 nm diameter of the holoenzyme. These towers protrude from the cytoplasmic side of the central mesh. There appears to be a local organization of CaMKII, as judged by fact that the nearest-neighbor distances are nearly invariant over a wide range of labeling density for CaMKII. The average density of CaMKII holoenzymes is highly variable, ranging from zero to values approaching a tightly packed state. This variability is significantly higher than that for PSD-95 and is consistent with an information storage role for CaMKII.
  • Article
    Persistent accumulation of calcium/calmodulin-dependent protein kinase II in dendritic spines after induction of NMDA receptor-dependent chemical long-term potentiation
    (Society for Neuroscience, 2004-10-20) Otmakhov, Nikolai ; Tao-Cheng, Jung-Hwa ; Carpenter, Stephen ; Asrican, Brent ; Dosemeci, Ayse ; Reese, Thomas S. ; Lisman, John E.
    Calcium/calmodulin-dependent protein kinase II (CaMKII) is a leading candidate for a synaptic memory molecule because it is persistently activated after long-term potentiation (LTP) induction and because mutations that block this persistent activity prevent LTP and learning. Previous work showed that synaptic stimulation causes a rapidly reversible translocation of CaMKII to the synaptic region. We have now measured green fluorescent protein (GFP)-CaMKIIα translocation into synaptic spines during NMDA receptor-dependent chemical LTP (cLTP) and find that under these conditions, translocation is persistent. Using red fluorescent protein as a cell morphology marker, we found that there are two components of the persistent accumulation. cLTP produces a persistent increase in spine volume, and some of the increase in GFP-CaMKIIα is secondary to this volume change. In addition, cLTP results in a dramatic increase in the bound fraction of GFP-CaMKIIα in spines. To further study the bound pool, immunogold electron microscopy was used to measure CaMKIIα in the postsynaptic density (PSD), an important regulator of synaptic function. cLTP produced a persistent increase in the PSD-associated pool of CaMKIIα. These results are consistent with the hypothesis that CaMKIIα accumulation at synapses is a memory trace of past synaptic activity.